IMPROVED CLEANING METHOD
Field of the Invention
[0001] The present invention relates to the aqueous cleaning of soiled substrates,
specifically textile fibres and fabrics, using a cleaning system which comprises nonpolymeric
particles, or mixtures of polymeric and non-polymeric particles. More
specifically, the invention is concerned with the use of such particles in a system
adapted to optimise mechanical interaction between said particles and substrates, and
to facilitate the easy removal of said particles from said substrates after completion of
cleaning, thereby facilitating re-use of the particles for subsequent cleaning operations.
Background to the Invention
[0002] Aqueous cleaning processes are a mainstay of both domestic and industrial
textile fabric washing. On the assumption that the desired level of cleaning is achieved,
the efficacy of such processes is usually characterised by their levels of consumption of
energy, water and detergent. In general, the lower the requirements with regard to
these three components, the more efficient the washing process is deemed. The
downstream effect of reduced water and detergent consumption is also significant, as
this minimises the need for disposal of aqueous effluent, which is both extremely costly
and detrimental to the environment.
[0003] Such washing processes, whether involving domestic washing machines or
their industrial equivalents (usually referred to as washer extractors) involve aqueous
submersion of fabrics followed by soil removal, aqueous soil suspension, and water
rinsing. In general, the higher the level of energy (or temperature), water and detergent
which is used, the better the cleaning. The key issue, however, concerns water
consumption, as this sets the energy requirements (in order to heat the wash water),
and the detergent dosage (to achieve the desired detergent concentration). In addition,
the water usage level defines the mechanical action of the process on the fabric, which
is another important performance parameter; this is the agitation of the cloth surface
during washing, which plays a key role in releasing embedded soil. In aqueous
processes, such mechanical action is provided by the water usage level in combination
with the drum design for any particular washing machine. In general terms, it is found
that the higher the water level in the drum, the better the mechanical action. Hence,
there is a dichotomy created by the desire to improve overall process efficiency (i.e. the
reduction of energy, water and detergent consumption), and the need for efficient
mechanical action in the wash. For domestic washing in particular there are defined
wash performance standards specifically designed to discourage the use of such higher
levels in practice, in addition to the obvious cost penalties which are associated with
such usage.
[0004] Current efficient domestic washing machines have made significant strides
towards minimising their consumptions of energy, water and detergent. EU Directive
92/75/CEE sets a standard which defines washing machine energy consumption in
kWh/cycle (cotton setting at 60°C), such that an efficient domestic washing machine will
typically consume < 0.19 kWh/kg of washload in order to obtain an 'A' rating. If water
consumption is also considered, then 'A' rated machines use < 9.7 litres/kg of
washload.
[0005] The most recent system in the EU (arising from Commission Delegated
Regulation 1061/2010, introduced from 20 December, 201 1) has, however, seen a
switch to a new rating system for domestic washing machines. This considers
annualised energy and water consumptions, and derives an energy efficiency index
(EEI) based on a defined weekly set of wash cycles (3 off 60°C at full load, 2 off 60°C
at half load, and 2 off 40°C at half load). The total energy consumption of these
washes (plus weighted values for the 'off mode' and 'left-on' mode power
consumptions) is then averaged to a daily figure (by division by 7). The resulting figure
is then multiplied by 220 - the assumed average number of washes per annum, to
calculate the annual energy consumption (AEc) in KWh. The EEI is then calculated by
dividing the AEc by a standard annual energy consumption (SAEc = [47 x c] + 5 1.7),
where c is the washload capacity for the machine. An EEI value of < 46 results in an
A+++ energy efficiency rating. A similar approach is taken with the water consumption
to arrive at the AWc (the water consumption for the same weekly set of wash cycles,
averaged to daily consumption and annualised). This value is, however, simply
displayed as an annual consumption in litres/annum.
[0006] Detergent dosage is then driven by manufacturer recommendations but, again,
in the domestic market, for a concentrated liquid formulation, a figure of 35 ml (or 37 g)
for a 4-6 kg washload in soft and medium hardness water, increasing to 52 ml (or 55 g)
for a 6-8 kg washload (or in hard water or for very dirty items) is typical (see, for
example, Unilever pack dosage instructions for Persil® Small & Mighty). Hence, for a 4-
6 kg washload in soft/medium water hardness, this equates to a detergent dosage of
7.4-9.2 g/kg whilst, for a 6-8 kg washload (or in hard water or for very dirty items), the
range is 6.9-9.2 g/kg.
[0007] Energy, water and detergent consumptions in the industrial washing process
(washer extractors) are considerably different, however, and usages all three resources
are less constrained, since these are principal factors in reducing cycle time - which is,
of course, more of a consideration than in the case of domestic processes. For a
typical industrial washer extractor (25 kg washload rated and above), energy
consumption is > 0.30 kWh/kg, water usage is at -20 litres/kg, and detergent is much
more heavily dosed than for domestic washing. The exact level of detergent used will
depend on the amount of soiling, but a range of 18-70 g/kg is representative.
[0008] Thus, it can be taken from the above discussion that it is the performance
levels in the domestic sector which set the highest standard for an efficient fabric
washing process, and that these are: an energy consumption of < 0.19 kWh/kg or an
EEI of < 46, a water usage of < 9.7 litres/kg, and a detergent dosage of approximately
8.0 g/kg (8.5 ml/kg). However, as previously observed, it is becoming increasingly
difficult to reduce the water (and, hence, energy and detergent) levels in a purely
aqueous process, due to the minimum requirement to wet the fabric thoroughly, the
need to provide sufficient excess water to suspend the soil removed in an aqueous
liquor and, finally, the need to rinse the fabric.
[0009] Heating of the wash water is then the principal use of energy, and a minimum
level of detergent becomes necessary in order for an effective concentration to be
reached at the operating wash temperature. Means to improve mechanical action
without increasing the water level used would, therefore, make any aqueous wash
process significantly more efficient (i.e. yield further reductions in energy, water and
detergent consumption). It should be noted that mechanical action itself has a direct
effect on the detergent level, since the greater the level of soil removal which is
achieved through physical force, the less that is required of the detergent chemistry.
However, increasing the mechanical action in a purely aqueous washing process has
certain associated drawbacks. Fabric creasing readily occurs in such processes, and
this acts to concentrate the stresses from mechanical action at each crease, resulting in
localised fabric damage. Prevention of such fabric damage (i.e. fabric care) is of
primary concern to the domestic consumer and the industrial user.
[0010] In the light of these challenges which are associated with aqueous washing
processes, the present inventors have previously devised a new approach to the
problem, which allows the deficiencies demonstrated by the methods of the prior art to
be overcome. The method which is provided eliminates the requirement for the use of
large volumes of water, but is still capable of providing an efficient means of cleaning
and stain removal, whilst also yielding economic and environmental benefits.
[001 1] Thus, in WO-A-2007/1 28962 there is disclosed a method and formulation for
cleaning a soiled substrate, the method comprising the treatment of the moistened
substrate with a formulation comprising a multiplicity of polymeric particles, wherein the
formulation is free of organic solvents. Preferably, the substrate is wetted so as to
achieve a substrate to water ratio of between 1:0.1 to 1:5 w/w, and optionally, the
formulation additionally comprises at least one cleaning material, which typically
comprises a surfactant, which most preferably has detergent properties. In preferred
embodiments, the substrate comprises a textile fibre and the polymeric particles may,
for example, comprise particles of polyamides, polyesters, polyalkenes, polyurethanes
or their copolymers, but are most preferably in the form of nylon beads.
[0012] The use of this particle-based cleaning method, however, presents a
requirement for the cleaning particles to be efficiently separated from the cleaned
substrate at the conclusion of the cleaning operation, and this issue is addressed in
WO-A-201 0/094959, which provides a novel design of cleaning apparatus requiring the
use of two internal drums capable of independent rotation, and which finds application
in both industrial and domestic cleaning processes.
[0013] In co-pending WO-A-201 1/064581 , there is provided a further apparatus which
facilitates efficient separation of cleaning particles from the cleaned substrate at the
conclusion of the cleaning operation, and which comprises a perforated drum and a
removable outer drum skin which is adapted to prevent the ingress or egress of fluids
and solid particulate matter from the interior of the drum, the cleaning method requiring
attachment of the outer skin to the drum during a wash cycle, after which the skin is
removed prior to operating a separation cycle to remove the cleaning particles, following
which the cleaned substrate is removed from the drum.
[0014] In a further development of the apparatus of WO-A-201 1/064581 , there is
disclosed in co-pending WO-A-201 1/098815 a process and apparatus which provides
for continuous circulation of the cleaning particles during the cleaning process, and
thereby dispenses with the requirement for the provision of an outer skin.
[0015] The apparatus and methods disclosed in the foregoing prior art documents
have been highly successful in providing an efficient means of cleaning and stain
removal which also yields significant economic and environmental benefits.
[0016] In co-pending PCT Patent Application No. PCT/GB201 1/0521 17 the polymeric
particle-based cleaning method, and the separation of said cleaning particles from the
cleaned substrate, are both further improved by careful control of polymeric particle
size, shape and density, as well as process parameters. A cleaning process is
achieved which facilitates excellent cleaning performance at surprisingly low cleaning
temperatures (i.e. low energy), and with reduced levels of added detergents, whilst also
maintaining the original low water consumption. In the present invention, even further
improvements to this cleaning process are achieved by the use of enhanced methods
which move away from the use of only polymeric cleaning particles.
[0017] The present inventors have now established that certain non-polymeric
particles can enhance the mechanical action in the wash process such that, most
particularly in combination with polymeric particles, there is a surprising benefit
achieved in overall cleaning performance. Specifically, high density (> 3.5 g/cm3) nonpolymeric
particles of similar size and shape to those described in PCT Patent
Application No. PCT/GB201 1/0521 17 have been found to provide this enhanced effect.
The non-polymeric particles are significantly more dense than the polymeric particles
they are mixed with, due to the nature of the different materials used (the specific
examples of non-polymeric particles are glass and metal). Hence, the benefit of the
present invention is in still further enhancing cleaning performance even at the already
low cleaning temperatures, reduced levels of added detergents, and low water
consumptions disclosed in PCT Patent Application No. PCT/GB201 1/0521 17.
[0018] As previously discussed, effective targets for these savings would be
significant reductions below an energy consumption of 0.19 kWh/kg or an EEI of < 46, a
water usage of < 9.7 litres/kg, and a detergent dosage of approximately 8.0 g/kg (8.5
ml/kg). The current invention allows a new washing process capable of achieving these
targets, whilst also facilitating reduced localised fabric damage in the washed substrate
by virtue of the increased uniformity of the mechanical action of the particles with the
fabric surface.
[0019] In addition, removal levels of the non-polymeric particles from the fabric
washload at the end of the cleaning process are at least as efficient as for the removal
of polymeric particles in PCT Patent Application No. PCT/GB201 1/0521 17.
Summary of the Invention
[0020] The present invention derives from an appreciation on the part of the inventors
that optimum cleaning performance can be achieved as a result of improved
mechanical interaction between substrate and cleaning media, as well as controlled soil
adsorption and absorption onto the surface of the media. This can be effected as a
function of the chemical composition, number, size, shape, density, and hence mass, of
the particles of cleaning media and the free volume within the vessel in which the
cleaning operation takes place, in addition to the G force dictated by its speed of
rotation. Free volume in this context refers to the space inside the vessel which
remains unoccupied by washload or particulate cleaning media, and G force is defined
on the basis of the centripetal forces which are acting.
[0021] For the particle itself, mechanical interaction with the substrate is a function of
its size, shape and density. Shape is a secondary effect, with cylinders of circular cross
section providing more mechanical action than, for example, perfect spheres due to the
defined edges at the circumferences of their circular faces. As individual particle size,
and therefore mass, increases so does the mechanical action of the particle, but there
is a balance with cleaning performance, since a consequence of the use of very large
particles is that fewer particles are used to provide the same overall mass of particles.
In the case of polymeric particles, that also results in reduced surface area with which
soil adsorption and absorption onto the particle surface can occur.
[0022] Non-polymeric particles, such as glass and metals, generally rely on
mechanical action rather than soil adsorption or absorption in order to effect cleaning.
Glasses, ceramics and metals, for example, have chemically inert surfaces, so there is
little adsorption and no absorption of soil at the particle surface. The advantage of such
non-polymeric particles, however, is that they are much more dense than the equivalent
sized and shaped polymeric particles; hence, they have much stronger mechanical
actions. In mixing these two particle types therefore, a skilled person might expect that
where the mechanical action of the polymeric particle is relatively poor, adding nonpolymeric
particles would give rise to some improvement in cleaning performance. It
could also be expected that this improvement should be governed by the ratio of
polymeric to non-polymeric particles, and that a rule of mixtures may apply (i.e. a linear
relationship as the mixture ratio changes from 100% polymeric to 100% non-polymeric
particles). If the polymer already has reasonably good mechanical action, however, the
addition of non-polymeric particles should have less effect.
[0023] Surprisingly, however, it has been established that since polymeric particles
have relatively poor mechanical action, the addition of non-polymeric particles has
increased cleaning performance far beyond what could reasonably be expected.
Indeed, improvements have been achieved which greatly exceed that predicted by a
rule of mixtures approach, as described above. In addition it has been found that the
nature of the non-polymeric particle itself is a key factor in generating this improvement.
Specifically, only non-polymeric particles of density > 3.5 g/cm3 (mass > 190 mg) show
significant cleaning benefits for the particle size ranges used. Furthermore, for
polymers with reasonably good mechanical action - even such that their cleaning
performance exceeds that of the non-polymeric particle added - very considerable
improvements in cleaning performance can still be achieved by mixing the two particle
types. It has become clear, therefore, that the efficacy of cleaning with polymeric
particles can be considerably enhanced by the addition of certain non-polymeric
particles, to an extent beyond what might reasonably be expected by a skilled person.
[0024] The use of non-polymeric particles alone can also enhance cleaning
performance over conventional aqueous wash processes, but to a lesser extent than is
achieved by the use of mixtures of non-polymeric and polymeric particles.
[0025] Thus, according to a first aspect of the present invention, there is provided a
method for the cleaning of a soiled substrate, said method comprising treating the
substrate with a solid particulate cleaning material and wash water, said treatment
being carried out in an apparatus comprising a drum comprising perforated side walls
and having a capacity of between 5 and 50 litres for each kg of fabric in the washload,
wherein said solid particulate cleaning material comprises a multiplicity of non-polymeric
particles at a particle to fabric addition level of 0.1 :1-10:1 by mass, each of said
particles being substantially cylindrical or spherical in shape and having an average
density in the range of 3.5-12.0 g/cm3 and an average volume in the range of 5-275
mm3, and wherein said drum comprising perforated side walls is rotated at a speed
which generates G forces in the range of from 0.05 to 900 G.
[0026] In particularly favoured embodiments of the invention, said solid particulate
cleaning material additionally comprises a multiplicity of polymeric particles, each of
said particles being substantially cylindrical or spherical in shape and having an
average density in the range of 0.5-2.5 g/cm3 and an average volume in the range of 5-
275 mm3.
[0027] The non-polymeric particles may comprise particles of glass, silica, stone,
wood, or any of a variety of metals or ceramic materials. Suitable metals include, but
are not limited to, zinc, titanium, chromium, manganese, iron, cobalt, nickel, copper,
tungsten, aluminium, tin and lead, and alloys thereof. Suitable ceramics include, but
are not limited to, alumina, zirconia, tungsten carbide, silicon carbide and silicon nitride.
[0028] The polymeric particles may comprise either foamed or unfoamed polymeric
materials. Furthermore, the polymeric particles may comprise polymers which are either
linear or crosslinked.
[0029] The polymeric particles preferably comprise polyalkenes such as polyethylene
and polypropylene, polyamides, polyesters or polyurethanes. Preferably, however, said
polymeric particles comprise polyamide or polyester particles, most particularly particles
of nylon, polyethylene terephthalate or polybutylene terephthalate, most preferably in
the form of beads. Said polyamides and polyesters are found to be particularly
effective for aqueous stain/soil removal, whilst polyalkenes are especially useful for the
removal of oil-based stains.
[0030] Optionally, copolymers of the above polymeric materials may be employed for
the purposes of the invention. Specifically, the properties of the polymeric materials
may be tailored to specific requirements by the inclusion of monomeric units which
confer particular properties on the copolymer. Thus, the copolymers may be adapted to
attract particular staining materials by comprising monomers which, inter alia, are
ionically charged, or include polar moieties or unsaturated organic groups.
[0031] In embodiments of the invention wherein said solid particulate cleaning material
comprises a multiplicity of non-polymeric particles and a multiplicity of polymeric
particles, said polymeric particles may be present in any amount, typically from 0.1% to
99.9%. Consequently, embodiments of the invention are envisaged wherein the ratio of
non-polymeric particles to polymeric particles may be anywhere from 99.9%:0.1% to
0.1%:99.9%. Certain embodiments envisage ratios of from 90.0%: 10.0% to
25.0%:75.0%, or from 85.0%: 15.0% to 40.0%:60.0%, of non-polymeric particles to
polymeric particles.
[0032] In further embodiments of the invention, said non-polymeric particles may
comprise coated non-polymeric particles. Most particularly, said non-polymeric particles
may comprise a non-polymeric core material and a shell comprising a coating of a
polymeric material. In a particular embodiment, said core may comprise a metal core,
typically a steel core, and said shell may comprise a polyamide coating, for example a
coating of nylon.
[0033] In preferred embodiments of the invention, the drum comprising perforated side
walls comprises a rotatably mounted cylindrical cage.
[0034] The volume of wash water added to the system provides a wash water to fabric
ratio which is typically between 5.0:1 and 0.1 : 1 w/w, and the overall volumes of water
which are employed (including rinse water) are significantly lower than in conventional
washing processes.
[0035] In typical embodiments of the invention, the formulation additionally comprises
at least one additional cleaning agent, which most preferably comprises at least one
detergent composition.
[0036] The generation of suitable G forces, in combination with the action of the solid
particulate cleaning material, is a key factor in achieving an appropriate level of
mechanical action on the soiled substrate. G is a function of the drum size and the
speed of rotation of the drum and, specifically, is the ratio of the centripetal force
generated at the inner surface of the cage to the static weight of the washload. Thus,
for a cage of inner radius r (m), rotating at R (rpm), with a washload of mass M (kg), and
an instantaneous tangential velocity of the cage v (m/s), and taking g as the
acceleration due to gravity at 9.81 m/s2:
Centripetal force = Mv2/r
Washload static weight = Mg
v = 2TTrR/60
Hence, G = 4n 2r2R2/3600rg = 4TT2rR2/3600g = 1.18 x 10 rR2
When, as is usually the case, r is expressed in centimetres, rather than metres, then:
G = 1. 1 18 x 10 rR2
Hence, for a drum of radius 49 cm rotating at 800 rpm, G = 350.6.
[0037] In an embodiment of the invention, a cylindrical drum having a diameter of 98
cm is rotated at a speed of 30-800 rpm in order to generate G forces of 0.49-350.6 at
different stages during the cleaning process. In examples of alternative embodiments
of the invention, a 48 cm diameter drum rotating at 1600 rpm can generate 688 G,
whilst a 60 cm diameter drum at the same speed of rotation generates 860 G.
[0038] In preferred embodiments of the invention, the claimed method additionally
provides for separation and recovery of the non-polymeric particles, and polymeric
particles which are preferably present, and these may then be re-used in subsequent
washes.
[0039] The non-polymeric particles, and polymeric particles which are preferably
present, are of such a shape and size as to allow for good flowability and intimate
contact with the soiled substrate, which typically comprises a textile fabric. A variety of
shapes of particles can be used, such as cylindrical, spherical or cuboid; appropriate
cross-sectional shapes can be employed including, for example, annular ring, dog-bone
and circular. Non-polymeric particles comprising naturally occurring materials such as
stone may have various shapes, dependent on their propensity to cleave in a variety of
different ways during manufacture. Most preferably, however, said particles comprise
cylindrical or spherical beads.
[0040] It has been established that the combination of particle size, shape and density
is such that the mechanical action of the particle with the fabric is optimised, it being
sufficiently vigorous to provide effective cleaning but, at the same time, uniform and
gentle enough to reduce fabric damage when compared with conventional aqueous
processes. It is, in particular, the uniformity of the mechanical action generated by the
chosen particles across the entire fabric surface that is the key factor in this regard.
The particle parameters are also controlled so as to allow for easy separation of the
particles from the fabric washload at the end of the wash process. Thus, particle size
and shape may be controlled in order to minimise entanglement with the fabric, and the
combination of suitable particle density with low G (< 1) and high free volume in the
washing machine tumbling process together promote particle removal under gravity
through the perforations in the drum sidewalk
[0041] All particles may have smooth or irregular surface structures and can be of
solid or hollow construction. Non-polymeric particles have an average density in the
range of from 3.5-12.0 g/cm3, preferably from 5.0-10.0 g/cm3, more preferably from 6.0-
9.0 g/cm3. Polymeric particles have an average density in the range of 0.5-2.5 g/cm3,
preferably from 0.55-2.0 g/cm3, more preferably from 0.6-1 .9 g/cm3. The average
volume of both the non-polymeric and polymeric particles is in the range of 5-275 mm3,
preferably from 8-140 mm3, more preferably from 10-120 mm3.
[0042] In the case of cylindrical particles - both non-polymeric and polymeric - of oval
cross section, the major cross section axis length, a, is typically in the range of from 2.0-
6.0 mm, more typically from 2.2-5.0 mm, most typically from 2.4-4.5 mm, and the minor
cross section axis length, b, is typically in the range of from 1.3-5.0 mm, more typically
from 1.5-4.0 mm, and most typically from 1.7-3.5 mm (a > b). The length of such
particles, h, is typically from 1.5-6.0 mm, more typically from 1.7-5.0 mm, and most
typically from 2.0-4.5 mm (h/b is typically in the range of from 0.5-1 0).
[0043] For cylindrical particles - both non-polymeric and polymeric - of circular cross
section, the typical cross section diameter, dc, is in the range of from 1.3-6.0 mm, more
typically from 1.5-5.0 mm, and most typically from 1.7-45.5 mm. The typical length, hc,
of such particles is again from 1.5-6.0 mm, more typically from 1.7-5.0 mm, and most
typically from 2.0-4.5 mm (hc/dc is typically in the range of from 0.5-1 0).
[0044] In the case of both non-polymeric and polymeric spherical particles (not perfect
spheres) the diameter, ds, is typically in the range of from 2.0-8.0 mm, more typically in
the range of from 2.2-5.5 mm, and most typically from 2.4-5.0 mm.
[0045] In embodiments where the particles, whether non-polymeric or polymeric, are
perfect spheres, the diameter, dps , is typically in the range of from 2.0-8.0 mm, more
typically from 3.0-7.0 mm, and most typically from 4.0-6.5 mm.
[0046] In accordance with the present invention, the selection of specific particle type
(non-polymeric and polymeric if used) for a given cleaning operation is particularly
important in optimising fabric care. Thus, particle size, shape, mass and material must
all be considered carefully in respect of the particular substrate which is to be cleaned,
so that particle selection is dependent on the nature of the garments to be cleaned, i.e.
whether they comprise cotton, polyester, polyamide, silk, wool, or any of the other
common textile fibres or blends which are commonly in use.
[0047] Said rotatably mounted cylindrical cage is comprised in any suitable cleaning
apparatus comprising a housing and access means, allowing access to the interior of
said cylindrical cage, suitable examples of which are disclosed in WO-A-201 0/094959,
WO-A-20 11/064581 and WO-A-201 1/098815.
[0048] Optionally, said rotatably mounted cylindrical cage may be concentrically
located within a rotatably mounted cylindrical drum having a greater diameter than said
cage, wherein said cage and said drum are concentrically located within a stationary
cylindrical drum having a greater diameter than said rotatably mounted drum, and
wherein said rotatably mounted cylindrical cage and said rotatably mounted cylindrical
drum are adapted to rotate independently.
[0049] More preferably, however, said rotatably mounted cylindrical cage is mounted
in a first chamber within said housing means, which also comprises a second chamber
located adjacent said cylindrical cage. Said apparatus typically also comprises at least
one recirculation means and a multiplicity of delivery means.
[0050] In certain embodiments of the invention, said apparatus additionally comprises
sealing means, removably attached to the outer surface of the cylindrical side walls of
said rotatably mounted cylindrical cage, and adapted to prevent the ingress or egress of
fluids and solid particulate matter from the interior of said cage.
[0051] In alternative embodiments of the invention, said apparatus additionally
comprises pumping means, and said rotatably mounted cylindrical cage comprises a
drum comprising perforated side walls, wherein up to 60% of the surface area of said
side walls comprises perforations, and said perforations comprise holes having a
diameter of no greater than 25.0 mm.
[0052] As a consequence of employing the cleaning method of the present invention,
excellent cleaning performance may be achieved whilst using reduced levels of
detergents and much lower cleaning temperatures (i.e. lower energy consumption),
whilst also maintaining low water consumption levels. Thus, cleaning operations
according to the invention, whilst possible at temperatures of up to 95°C, are typically
carried out at temperatures not exceeding 75°C, and optimum performance is generally
achieved at 5-40°C. As an approximate guide, it is found that if a conventional aqueous
cleaning process requires a wash temperature of T°C, then the process according to
the present invention will provide superior cleaning at temperatures in the range of T-
10°C to T-25°C.
[0053] Removal of the particles from the fabric washload at the end of the cleaning
process is expedited on the basis of the specific size, shape and density of the particles
used, and also by control of process parameters, in order to enable bead re-use in
subsequent cleaning processes.
[0054] Thus, the present inventors have provided a process for the cleaning of soiled
substrates which provides improved cleaning performance, reduced damage to the
substrate being cleaned, and significantly reduced consumption of energy, detergent
and water. These improvements result from improved mechanical interaction between
the cleaning material and the substrate, which result from the careful selection of both
apparatus parameters and the physical properties of the solid particulate cleaning
material as hereinbefore defined. Furthermore, by virtue of this selection of parameters
and properties, the process allows for the efficient collection of the solid particulate
cleaning material after completion of the process such that it may be re-used in
subsequent cleaning procedures.
[0055] A further aspect of the invention envisages a cleaning composition as
hereinbefore defined comprising a solid particulate cleaning composition and at least
one additional cleaning agent. Typically, said at least one additional cleaning agent
comprises at least one detergent composition.
[0056] Said solid particulate cleaning material comprises a multiplicity of nonpolymeric
particles and, in particularly favoured embodiments of the invention, said solid
particulate cleaning material additionally comprises a multiplicity of polymeric particles.
Detailed Description of the Invention
[0057] In apparatus employed in the method of the invention, the access means
typically comprises a hinged door mounted in the housing, which may be opened to
allow access to the inside of the cylindrical cage, and which may be closed in order to
provide a substantially sealed system. Preferably, the door includes a window.
[0058] Said rotatably mounted cylindrical cage may be mounted vertically within said
housing means but, most preferably, is mounted horizontally within said housing
means. Consequently, in preferred embodiments of the invention, said access means
is located in the front of the apparatus, providing a front-loading facility. When the
rotatably mounted cylindrical cage is vertically mounted within the housing means, the
access means is located in the top of the apparatus, providing a top-loading facility.
[0059] Rotation of said rotatably mounted cylindrical cage is effected by use of drive
means, which typically comprises electrical drive means, in the form of an electric
motor. Operation of said drive means is effected by control means which may be
programmed by an operative.
[0060] The method according to the invention preferably comprises performing, in
sequence, the steps of:
(a) washing;
(b) first extraction of excess water;
(c) first separation of particles of solid particulate cleaning material;
(d) rinsing;
(e) second extraction of excess water;
(f) optionally repeating steps (d) and (e) at least once; and
(g) second separation of particles of solid particulate cleaning material.
[0061] Said solid particulate cleaning material typically comprises a multiplicity of nonpolymeric
particles and, in particularly favoured embodiments of the invention, said solid
particulate cleaning material additionally comprises a multiplicity of polymeric particles.
[0062] Said first separation of cleaning particles typically removes > 50% of the
particles, whilst the second separation of cleaning particles ensures removal of > 99%
of these particles. Optionally, the first separation of cleaning particles can be extended
to provide removal of > 99.9% of particles, but it is more efficient to take advantage of
steps (d) and (e), as these also inherently remove some particles, before moving to step
(g) for final separation. This is particularly true if steps (d) and (e) are repeated.
[0063] Preferably, steps (d) and (e) are repeated several times, typically at least 2-3
times, but possibly up to 10 times.
[0064] Said rotatably mounted cylindrical cage more preferably has a volume of
between 5 and 50 litres for each kg of fabric in the washload. Preferred rates of
rotation of said rotatably mounted cylindrical cage are sufficient to give G forces of
between 0.05 and 900 G. Typically the washing process is carried out at between 0.05
and 0.95 G, and the rinsing water is added under similar conditions, before extraction of
the excess water at higher G force, typically 5.5 to 350 G. Separation of the particles
from the fabric is carried out at 0.05 to 0.95 G. After separation, the particles are
recovered for re-use in subsequent cleaning processes.
[0065] Thus, for a 98 cm diameter cage, the speeds of rotation are advantageously in
the range of 10-800 rpm. Typically the washing process is carried out between 10 and
42 rpm and the rinsing water is added under similar conditions, before extraction of the
excess water takes place at 100-800 rpm. Separation of the particles from the fabric is
carried out at 10-42 rpm, and the separated particles are recovered for re-use in
subsequent cleaning processes.
[0066] According to the method of the invention, said apparatus operates in
conjunction with soiled substrates and cleaning media comprising solid particulate
material, which is in the form of a multiplicity of non-polymeric particles which preferably
additionally comprises a multiplicity of polymeric particles. These particles are required
to be efficiently circulated to promote optimum cleaning performance and the
apparatus, therefore, preferably includes circulation means. Thus, the inner surface of
the cylindrical side walls of said rotatably mounted cylindrical cage preferably comprises
a multiplicity of spaced apart elongated protrusions affixed essentially perpendicularly to
said inner surface. Preferably, said protrusions additionally comprise air amplifiers
which are typically driven pneumatically and are adapted so as to promote circulation of
a current of air within said cage. Typically said apparatus comprises from 3 to 10, most
preferably 4, of said protrusions, which are commonly referred to as lifters.
[0067] In operation, agitation is provided by rotation of said rotatably mounted
cylindrical cage. However, in preferred embodiments of the invention, there is also
provided additional agitating means, in order to facilitate the efficient removal of
residual solid particulate material at the conclusion of the cleaning operation.
Preferably, said agitating means comprises an air jet.
[0068] Said housing means is connected to standard plumbing features, thereby
preferably providing at least one recirculation means, in addition to a multiplicity of
delivery means, by virtue of which at least water and, optionally, cleaning agents such
as surfactants, enzymes and bleaches may be introduced into the apparatus. Said
apparatus may additionally comprise means for circulating air within said housing
means, and for adjusting the temperature and humidity therein. Said means may
typically include, for example, a recirculating fan, an air heater, a water atomiser and/or
a steam generator. Additionally, sensing means may also be provided for determining
the temperature and humidity levels within the apparatus, and for communicating this
information to the control means.
[0069] According to preferred aspects of the invention, the at least one recirculation
means facilitates recirculation of said solid particulate material from a second chamber
to said rotatably mounted cylindrical cage, for re-use in subsequent cleaning processes.
Preferably, first recirculation means comprises ducting connecting said chamber and
said rotatably mounted cylindrical cage. More preferably, said ducting comprises
separating means for separating said solid particulate material from water and control
means, adapted to control entry of said solid particulate material into said cylindrical
cage.
[0070] Recirculation of solid particulate matter from said chamber to said rotatably
mounted cylindrical cage is achieved by the use of pumping means comprised in said
first recirculation means, wherein said pumping means are adapted to deliver said solid
particulate matter to said separating means and said control means, adapted to control
the re-entry of said solid particulate matter into said rotatably mounted cylindrical cage.
[0071] Preferably, said apparatus additionally includes a second recirculation means,
allowing for the return of water separated by said separating means to said second
chamber, thereby facilitating re-use of said water in an environmentally beneficial
manner. Preferably, said chamber comprises additional pumping means to promote
circulation and mixing of the contents thereof.
[0072] In a typical operation of a cleaning cycle according to the method of the
invention, soiled garments are first placed into said rotatably mounted cylindrical cage.
Tumbling begins (G < 1) and, then, the necessary amount of wash water is added,
together with any required additional cleaning agent, to said rotatably mounted
cylindrical cage. When the substrate has been uniformly wetted out (typically 1-2
minutes), the solid particulate cleaning material is also added to the rotatably mounted
cylindrical cage. Optionally, said materials are introduced via the first recirculation
means into the cylindrical cage. Alternatively, said additional cleaning agent may, for
example, be pre-mixed with said wash water and added via said separating means
located adjacent said cylindrical cage.
[0073] During the course of agitation by rotation of the cage, the fluids and a quantity
of the solid particulate material exit through the perforations in the cage and into a
second chamber of the apparatus. Thereafter, the solid particulate material may be re
circulated via the first recirculation means such that it is transferred to said separating
means, from which it is returned, in a manner controlled by said control means, to the
cylindrical cage for continuation of the washing operation. This process of continuous
circulation of the solid particulate material continues throughout the washing operation
until cleaning is completed.
[0074] Thus, the solid particulate material which exits through the perforations in the
walls of said rotatably mounted cylindrical cage and into said second chamber is
recirculated and reintroduced through said separation means and, by operation of
control means, through said feeder means, back into said cage, thereby to continue the
cleaning operation.
[0075] Typically, a wash cycle according the method of the invention comprises the
steps of:
(i) introducing a solid particulate cleaning material and water into a
second chamber of an apparatus as hereinbefore described
comprising a rotatably mounted cylindrical cage;
(ii) agitating said solid particulate cleaning material and water;
(iii) loading at least one soiled substrate into said rotatably mounted
cylindrical cage via access means;
(iv) closing the access means so as to provide a substantially sealed
system;
(v) causing the rotatably mounted cylindrical cage to rotate whilst
introducing wash water and any required additional cleaning
agent to uniformly wet out the substrate;
(vi) introducing said solid particulate cleaning material into said
rotatably mounted cylindrical cage, and operating the apparatus
for a wash cycle, wherein said rotatably mounted cylindrical cage
continues to rotate, and wherein fluids and solid particulate
cleaning material are caused to fall through perforations in said
rotatably mounted cylindrical cage into a second chamber in a
controlled manner;
(vii) operating pumping means so as to transfer fresh solid
particulate cleaning material and recycle used solid particulate
cleaning material to separating means;
(viii) operating control means so as to add said fresh and recycled
solid particulate cleaning material to said rotatably mounted
cylindrical cage in a controlled manner; and
(ix) continuing with steps (vi), (vii) and (viii) as required to effect
cleaning of the soiled substrate.
[0076] Optionally, said solid particulate cleaning material and water may be introduced
into said rotatably mounted cylindrical cage via recirculating means. More preferably,
however, said solid particulate cleaning material and water are introduced into said
rotatably mounted cylindrical cage via dosing means such as, for example, a fixedly
mounted spray nozzle. Most conveniently, said spray nozzle may be fixedly mounted
on said access means.
[0077] Preferably, additional cleaning agents are employed in said method, as further
discussed below. Said additional cleaning agents may be added to said second
chamber of said apparatus with said solid particulate cleaning material and introduced,
via the first recirculation means, into the cylindrical cage. Alternatively, an additional
cleaning agent is pre-mixed with water and added to said cylindrical cage via the
separating means during step (v). More preferably, however, said additional cleaning
agents are added to said cylindrical cage via said dosing means. The method of the
invention facilitates the use of reduced quantities of said additional cleaning agents.
[0078] In preferred embodiments of the invention, said cleaning agents may be added
to said cylindrical cage in multiple dosing steps during the cleaning operation, rather
than a single dosing step.
[0079] Preferably, pumping of said fresh and recycled solid particulate cleaning
material proceeds at a rate sufficient to maintain approximately the same level of
cleaning material in said rotatably mounted cylindrical cage throughout the cleaning
operation, and to ensure that the ratio of cleaning material to soiled substrate stays
substantially constant until the wash cycle has been completed.
[0080] On completion of the wash cycle, feeding of solid particulate cleaning material
into the rotatably mounted cylindrical cage ceases and the speed of rotation of the cage
is gradually increased in order to effect a measure of drying of the cleaned substrate.
Some solid particulate material is removed at this stage. Typically, the cage is rotated
at a rotation speed of between 100 and 800 rpm in order to achieve drying; for a 98 cm
diameter cage, a suitable speed of rotation would be around 600 rpm. Subsequently,
rotation speed is reduced and returned to the speed of the wash cycle so as to allow for
final removal of the solid particulate cleaning material. After separation, the solid
particulate cleaning material is recovered in order to allow for re-use in subsequent
cleaning processes.
[0081] Optionally, following initial drying at high rpm, said method may additionally
comprise a rinsing operation, wherein additional water may be added to said rotatably
mounted cylindrical cage in order to effect complete removal of any additional cleaning
agent employed in the cleaning operation. Water may be added to said cylindrical cage
via said separating means, or via dosing means such as, for example, a fixedly
mounted spray nozzle. Most conveniently, said spray nozzle may be fixedly mounted
on said access means. Water may also be added by overfilling the second chamber of
said apparatus with water such that it enters the first chamber and thereby enters into
said rotatably mounted cylindrical cage. Following rotation at the same speed as during
the wash cycle, water is removed from said cage by allowing the water level to fall, as
appropriate, and again increasing the speed of rotation to, typically, 100-800 rpm in
order to achieve a measure of drying of the substrate; a speed of rotation of around 600
rpm would, once again, be appropriate for a 98 cm diameter cage. Said rinsing and
drying cycles may be repeated as often as desired.
[0082] Optionally, said rinse cycle may be used for the purposes of substrate
treatment, involving the addition of treatment agents such as fluorescent brighteners,
perfumes, softeners and starch to the rinse water.
[0083] Said solid particulate cleaning material is preferably subjected to a cleaning
operation in said second chamber by sluicing said chamber with clean water in the
presence or absence of a cleaning agent, which may be selected from at least one of
surfactants, enzymes and bleaches. Alternatively, cleaning of the solid particulate
cleaning material may be achieved as a separate stage in said rotatably mounted
cylindrical cage. After cleaning, the solid particulate cleaning material is recovered such
that is available for use in subsequent cleaning processes.
[0084] Generally, any remaining solid particulate cleaning material on said at least one
substrate may be easily removed by shaking the at least one substrate. If necessary,
however, further remaining solid particulate cleaning material may be removed by
suction means, preferably comprising a vacuum wand.
[0085] The method of the invention may be applied to the cleaning of any of a wide
range of substrates including, for example, plastics materials, leather, paper, cardboard,
metal, glass or wood. In practice, however, said method is principally applied to the
cleaning of substrates comprising textile fibres and fabrics, and has been shown to be
particularly successful in achieving efficient cleaning of textile fabrics which may, for
example, comprise either natural fibres, such as cotton, or man-made and synthetic
textile fibres, for example nylon 6,6, polyester, cellulose acetate, or fibre blends thereof.
[0086] The solid particulate cleaning material typically comprises a multiplicity of nonpolymeric
particles which comprise particles of glass, silica, stone, wood, or any of a
variety of metals or ceramic materials, which particles may be solid or hollow in
structure.
[0087] In certain favoured embodiments of the invention, the solid particulate cleaning
material additionally comprises a multiplicity of polymeric particles, which may also be
solid or hollow in structure, and which comprise polyamide or polyester particles, most
particularly particles of nylon, polyethylene terephthalate or polybutylene terephthalate,
or copolymers thereof. The polymers may be foamed or unfoamed, and may be linear
or crosslinked. Various nylon or polyester homo- or co-polymers may be used
including, but not limited to, Nylon 6, Nylon 6,6, polyethylene terephthalate and
polybutylene terephthalate. Preferably, the nylon comprises Nylon 6,6 homopolymer
having a molecular weight in the region of from 5000 to 30000 Daltons, preferably from
10000 to 20000 Daltons, most preferably from 15000 to 16000 Daltons. The polyester
will typically have a molecular weight corresponding to an intrinsic viscosity
measurement in the range of from 0.3-1 .5 dl/g as measured by a solution technique
such as ASTM D-4603.
[0088] Optionally, the properties of the copolymers may be adapted, for example in
order to attract particular staining materials, by including monomer units in the polymer
chain which, inter alia, are ionically charged, or include polar moieties or unsaturated
organic groups. Examples of such groups may include, for example, acid or amino
groups, or salts thereof, or pendant alkenyl groups.
[0089] In said embodiments wherein said solid particulate cleaning material
additionally comprises a multiplicity of polymeric particles, said polymeric particles may
be present in any amount, typically from 0.1% to 99.9%, so that the ratio of nonpolymeric
particles to polymeric particles is generally anywhere from 99.9%:0.1% to
0.1%:99.9%. In specific embodiments, ratios of from 90.0%:10.0% to 25.0%:75.0%, or
from 85.0%: 15.0% to 40.0%:60.0%, of non-polymeric particles to polymeric particles
may be employed.
[0090] The volume of wash water added to the system is calculated so as to achieve a
wash water to fabric ratio which is preferably between 5.0:1 and 0.1 : 1 w/w; more
preferably, the ratio is between 2.0:1 and 0.8:1 , with particularly favourable results
having been achieved at ratios such as 1.75:1 , 1.5:1 , 1.2:1 and 1. 1 : 1 . Most
conveniently, the required amount of water is introduced into the rotatably mounted
cylindrical cage of the apparatus after loading of the soiled substrate into said cage. An
additional amount of water will migrate into the cage during the circulation of the solid
particulate cleaning material, but the amount of carry over is minimised by the action of
the separating means.
[0091] Whilst the method of the invention envisages the cleaning of a soiled substrate
by the treatment of a moistened substrate with a formulation which essentially consists
only of a multiplicity of non-polymeric particles, or of a multiplicity of non-polymeric
particles and polymeric particles, in the absence of any further additives, in more
preferred embodiments the formulation additionally comprises at least one additional
cleaning agent. Said at least one cleaning agent preferably comprises at least one
detergent composition.
[0092] The principal components of the detergent composition comprise cleaning
components and post-treatment components. Typically, the cleaning components
comprise surfactants, enzymes and bleach, whilst the post-treatment components
include, for example, anti-redeposition additives, perfumes and optical brighteners.
[0093] However, the detergent formulation may optionally include one or more other
additives such as, for example builders, chelating agents, dye transfer inhibiting agents,
dispersants, enzyme stabilizers, catalytic materials, bleach activators, polymeric
dispersing agents, clay soil removal agents, suds suppressors, dyes, structure
elasticizing agents, fabric softeners, starches, carriers, hydrotropes, processing aids
and/or pigments.
[0094] Examples of suitable surfactants may be selected from non-ionic and/or
anionic and/or cationic surfactants and/or ampholytic and/or zwitterionic and/or semipolar
nonionic surfactants. The surfactant is typically present at a level of from about
0.1%, from about 1%, or even from about 5% by weight of the cleaning compositions to
about 99.9%, to about 80%, to about 35%, or even to about 30% by weight of the
cleaning compositions.
[0095] The compositions may include one or more detergent enzymes which provide
cleaning performance and/or fabric care benefits. Examples of suitable enzymes
include, but are not limited to, hemicellulases, peroxidases, proteases, other cellulases,
other xylanases, lipases, phospholipases, esterases, cutinases, pectinases,
keratanases, reductases, oxidases, phenoloxidases, lipoxygenases, ligninases,
pullulanases, tannases, pentosanases, malanases, [beta]-glucanases, arabinosidases,
hyaluronidase, chondroitinase, laccase, and amylases, or mixtures thereof. A typical
combination may comprise a mixture of enzymes such as protease, lipase, cutinase
and/or cellulase in conjunction with amylase.
[0096] Optionally, enzyme stabilisers may also be included amongst the cleaning
components. In this regard, enzymes for use in detergents may be stabilised by various
techniques, for example by the incorporation of water-soluble sources of calcium and/or
magnesium ions in the compositions.
[0097] The compositions may include one or more bleach compounds and associated
activators. Examples of such bleach compounds include, but are not limited to,
peroxygen compounds, including hydrogen peroxide, inorganic peroxy salts, such as
perborate, percarbonate, perphosphate, persilicate, and mono persulphate salts (e.g.
sodium perborate tetrahydrate and sodium percarbonate), and organic peroxy acids
such as peracetic acid, monoperoxyphthalic acid, diperoxydodecanedioic acid, N,N'-
terephthaloyl-di(6-aminoperoxycaproic acid), N,N'-phthaloylaminoperoxycaproic acid
and amidoperoxyacid. Bleach activators include, but are not limited to, carboxylic acid
esters such as tetraacetylethylenediamine and sodium nonanoyloxybenzene sulfonate.
[0098] Suitable builders may be included in the formulations and these include, but
are not limited to, the alkali metal, ammonium and alkanolammonium salts of
polyphosphates, alkali metal silicates, alkaline earth and alkali metal carbonates,
aluminosilicates, polycarboxylate compounds, ether hydroxypolycarboxylat.es,
copolymers of maleic anhydride with ethylene or vinyl methyl ether, 1,3,5-
trihydroxybenzene-2,4,6-trisulphonic acid, and carboxymethyl-oxysuccinic acid, various
alkali metal, ammonium and substituted ammonium salts of polyacetic acids such as
ethylenediamine tetraacetic acid and nitrilotriacetic acid, as well as polycarboxylates
such as mellitic acid, succinic acid, oxydisuccinic acid, polymaleic acid, benzene 1,3,5-
tricarboxylic acid, carboxymethyloxysuccinic acid, and soluble salts thereof.
[0099] The compositions may also optionally contain one or more copper, iron and/or
manganese chelating agents and/or one or more dye transfer inhibiting agents.
[00100] Suitable polymeric dye transfer inhibiting agents include, but are not limited to,
polyvinylpyrrolidone polymers, polyamine N-oxide polymers, copolymers of Nvinylpyrrolidone
and N-vinylimidazole, polyvinyloxazolidones and polyvinylimidazoles or
mixtures thereof.
[00101] Optionally, the detergent formulations can also contain dispersants. Suitable
water-soluble organic materials are the homo- or co-polymeric acids or their salts, in
which the polycarboxylic acid may comprise at least two carboxyl radicals separated
from each other by not more than two carbon atoms.
[00102] Said anti-redeposition additives are physico-chemical in their action and
include, for example, materials such as polyethylene glycol, polyacrylates and carboxy
methyl cellulose.
[00103] Optionally, the compositions may also contain perfumes Suitable perfumes
are generally multi-component organic chemical formulations which can contain
alcohols, ketones, aldehydes, esters, ethers and nitrile alkenes, and mixtures thereof.
Commercially available compounds offering sufficient substantivity to provide residual
fragrance include Galaxolide ( 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-
hexamethylcyclopenta(g)-2-benzopyran), Lyral (3- and 4-(4-hydroxy-4-methyl-pentyl)
cyclohexene-1-carboxaldehyde and Ambroxan ((3aR,5aS,9aS,9bR)-3a,6,6,9atetramethyl-
2,4,5,5a,7,8,9,9b-octahydro-1 H-benzo[e][1] benzofuran). One example of a
commercially available fully formulated perfume is Amour Japonais supplied by
Symrise ® AG.
[00104] Suitable optical brighteners fall into several organic chemical classes, of which
the most popular are stilbene derivatives, whilst other suitable classes include
benzoxazoles, benzimidazoles, 1,3-diphenyl-2-pyrazolines, coumarins, 1,3,5-triazin-2-
yls and naphthalimides. Examples of such compounds include, but are not limited to,
4,4'-bis[[6-anilino-4(methylamino)-1 ,3,5-triazin-2-yl]amino]stilbene-2,2'-disulfonic acid,
4,4'-bis[[6-anilino-4-[(2-hydroxyethyl)methylamino]-1 ,3,5-triazin-2-yl]amino]stilbene-2,2'-
disulphonic acid, disodium salt, 4,4'-Bis[[2-anilino-4-[bis(2-hydroxyethyl)amino]-1 ,3,5-
triazin-6-yl]amino]stilbene-2,2'-disulfonic acid, disodium salt, 4,4'-bis[(4,6-dianilino-1 ,3,5-
triazin-2-yl)amino]stilbene-2, 2 -disulphonic acid, disodium salt, 7-diethylamino-4-
methylcoumarin, 4,4'-Bis[(2-anilino-4-morpholino-1 ,3,5-triazin-6-yl)amino]-2,2'-
stilbenedisulfonic acid, disodium salt, and 2,5-bis(benzoxazol-2-yl)thiophene.
[00105] Said agents may be used either alone or in any desired combination and may
be added to the cleaning system at appropriate stages during the cleaning cycle in
order to maximise their effects.
[00106] In any event, however, when the method of the invention is performed in the
presence of at least one additional cleaning agent, the quantity of said cleaning agent
required in order to achieve satisfactory cleaning performance is significantly reduced
from the quantities required with the methods of the prior art.
[00107] The ratio of solid particulate cleaning material to substrate is generally in the
range of from 0.1 : 1 to 10:1 w/w, preferably in the region of from 0.5:1 to 5:1 w/w, with
particularly favourable results being achieved with a ratio of between 1: 1 and 3:1 w/w,
and especially at around 2:1 w/w. Thus, for example, for the cleaning of 5 g of fabric,
10 g of non-polymeric particles, or the same mass of a mixture of non-polymeric and
polymeric particles, optionally coated with surfactant, would be employed. The ratio of
solid particulate cleaning material to substrate is maintained at a substantially constant
level throughout the wash cycle.
[00108] The method of the present invention may be used for either small or large
scale batchwise processes and finds application in both domestic and industrial
cleaning processes.
[00109] As previously noted, the method of the invention finds particular application in
the cleaning of textile fabrics. The conditions employed in such a cleaning system do,
however, allow the use of significantly reduced temperatures from those which typically
apply to the conventional wet cleaning of textile fabrics and, as a consequence, offer
significant environmental and economic benefits. Thus, typical procedures and
conditions for the wash cycle require that fabrics are generally treated according to the
method of the invention at, for example, temperatures of between 5 and 40°C for a
duration of between 5 and 45 minutes in a substantially sealed system. As an
approximate guide, it is found that if a conventional aqueous cleaning process requires
a wash temperature of T°C, then the process according to the present invention will
provide superior cleaning at temperatures in the range of T-10°C to T-25°C. Thereafter,
additional time is required for the completion of the rinsing and particle separation
stages of the overall process, so that the total duration of the entire cycle is typically in
the region of 1 hour.
[001 10] The results obtained are very much in line with those observed when carrying
out conventional wet (or dry) cleaning procedures with textile fabrics. The extent of
cleaning and stain removal achieved with fabrics treated by the method of the invention
is seen to be very good, with particularly outstanding results being achieved in respect
of hydrophobic stains and aqueous stains and soiling, which are often difficult to
remove. The energy requirement, the total volume of water used, and the detergent
consumption of the method of the invention are all significantly lower than those levels
associated with the use of conventional aqueous washing procedures, again offering
significant advantages in terms of cost and environmental benefits.
[001 11] The method of the invention also shows benefits in terms of reducing washingrelated
fabric damage. As previously observed, fabric creasing readily occurs in
conventional aqueous washing, and this acts to concentrate the stresses from the
mechanical action of the wash at each crease, resulting in localised fabric damage.
Prevention of such fabric damage (or fabric care) is of primary concern to the domestic
consumer and industrial user. The addition of non-polymeric particles, or mixtures of
non-polymeric and polymeric particles, according to the method of the invention
effectively reduces creasing in the wash by acting as a pinning layer on the fabric
surface in order to help prevent the folding action. The particles also inhibit interaction
between separate pieces of fabric in the wash by acting as a separation or spacing
layer, thereby reducing entanglement which is another major cause of localised fabric
damage. In the presently disclosed method, mechanical action is still present but,
critically, this is much more uniformly distributed as a result of the action of the nonpolymeric
particles. It is the localised aspect of the damage that determines the lifetime
of a garment under multiple washing.
[001 12] Thus, the method of the present invention provides for enhanced cleaning
performance in comparison with the methods of the prior art under equivalent energy,
water and detergent conditions; alternatively, equivalent cleaning performance may be
achieved at lower levels of all of energy water and detergent, together with reduced
fabric damage, as illustrated in the Examples appended hereto. Furthermore, removal
of the particles from the fabric washload at the end of the cleaning process is expedited
on the basis of the specific size, shape and density of the particles used, and also by
control of process parameters, in order to enable particle re-use in subsequent cleaning
processes.
[001 13] In a specific preferred embodiment of the invention, a soiled substrate is
placed in a rotatably mounted cylindrical cage of 98 cm diameter and a detergent
formulation comprising surfactant and enzymes is added in combination with a small
amount of wash water at ambient temperature via a spray nozzle mounted on the door
of the apparatus. The cage is rotated at 40 rpm to give a G force of 0.88. Thereafter,
the solid particulate cleaning material is introduced into said cage from said second
chamber and the process, comprising continuous recirculation of said material, is
continued for 5-50 minutes. A further amount of wash water containing bleach is added
during this time at either ambient or elevated temperature (in the former instance, the
bleach is a low temperature activated compound). Rotation is continued for several
minutes after the bleach solution has been added. Circulation is then discontinued in
order to end the wash process.
[001 14] The extraction stage of the cycle is then carried out in order to remove water
from the system, by rotating for about 2 minutes at a high G force of greater than 5.5;
preferably, said cage is rotated at about 600 rpm in order to generate a G force of
around 197.2. High speed rotation then ceases and a low G tumble (at around 40 rpm)
is carried out for approximately 5 minutes to remove the majority (> 50%) of the solid
particulate cleaning material remaining in the washload. Rinse water is then sprayed
into said cage via the nozzle for a few minutes, after which further rotation of the cage
at around 600 rpm takes place to remove the rinse water. The rinse process may be
repeated several times, generally up to 10 times, more preferably up to 5 times,
typically around 3 times. The rinse water which is added is not sufficient to submerge
the fabric in water, and is only used to the extent of resaturating the fabric ahead of the
next extraction stage. Optionally, fluorescent brighteners, perfumes, conditioners and
the like may be added during the course of the final spray rinse, following which the
cage is again rotated at low G (40 rpm) in order to allow for removal of the remaining
solid particulate cleaning material. The clean fabric may then be removed from the
apparatus.
[001 15] Further, in a typical example of an operating cycle according to the method of
the invention, an initial addition of solid particulate cleaning material (approximately 43
kg) is added to a washload of soiled substrate (15 kg) in a 98 cm diameter rotatably
mounted cylindrical cage, whilst rotating to generate 0.88 G (40 rpm). Thereafter,
further solid particulate cleaning material (10 kg) is pumped into said rotatably mounted
cylindrical cage via the separating means and control means approximately every 30
seconds throughout the duration of the wash cycle which may typically continue for
around 30 minutes. The system is thereby designed to pump and add solid particulate
cleaning material at a sufficient rate to maintain roughly the same level of solid
particulate cleaning material in the rotatably mounted cylindrical cage (approximately
2.9:1 by weight, for 43 kg of beads and 15 kg of fabric) throughout the wash.
[001 16] Thus, during the wash cycle, the solid particulate cleaning material is
continually falling out of the rotatably mounted cylindrical cage through its perforations,
and is being recycled and added, together with fresh cleaning material, via the
separating means and control means. This process may either be controlled manually,
or operated automatically. The rate of exit of the solid particulate cleaning material from
the rotatably mounted cylindrical cage is essentially controlled by means of its specific
design. The key parameters in this regard include the size of the perforations, the
number of perforations, the arrangement of the perforations within the cage and the G
force (or rotational speed) which is employed.
[001 17] Generally, the perforations are sized at around 2-3 times the average particle
diameter of the solid particulate cleaning material which, in a typical example, results in
perforations having a diameter of no greater than 25.0 mm. In a preferred embodiment
of the invention, a rotatably mounted cylindrical cage would be drilled so that only
around 34% of the surface area of the cylindrical walls of the cage comprises
perforations. Preferably, the perforations are banded in stripes or distributed evenly
over the cylindrical walls of the rotatably mounted cylindrical cage, but could be
exclusively located, for example, in one half of the cage.
[001 18] The rate of exit of the solid particulate cleaning material from the rotatably
mounted cylindrical cage is also affected by the speed of rotation of said cage, with
higher rotation speeds increasing the G force, although at G > 1 the fabric adheres to
the sides of the cage and prevents exit of the cleaning material. Hence, slower
rotational speeds have been found to provide optimum results in this regard, as they
allow the beads to fall from the fabric and through the perforations as the fabric opens
out more during tumbling. Rotational speeds resulting in a G force of < 1 are therefore
required (10-42 rpm in a 98 cm diameter cage). The G force (or rotational speed) is
also controlled so as to maximise the beneficial effect of the mechanical action of the
cleaning material on the substrate, and the most suitable G is generally found to be in
the region of 0.9 G (40 rpm in a 98 cm diameter cage).
[001 19] In addition, the moisture level in the wash also has an effect, with wetter
substrates tending to retain cleaning material for a longer time than drier substrates.
Consequently, overwetting of substrate can, if necessary, be employed in order to
further control the rate of exit of solid particulate cleaning material.
[00120] On completion of the wash cycle, addition of solid particulate cleaning material
to the rotatably mounted cylindrical cage is ceased, and the cage rpm is gradually
increased to give a G force of about 197.2 (600 rpm in a 98 cm diameter cylindrical
cage) for about 2 minutes in order to extract some liquid and dry the substrate to an
extent. High speed rotation then ceases and a low G tumble (at around 40 rpm) is
carried out for approximately 5 minutes to remove the majority (> 50%) of the solid
particulate cleaning material remaining in the washload. The rinsing cycles are then
carried out as hereinbefore described and the rotation G and rotational speed are finally
returned to the same values of < 1 and low (40) rpm as in the wash cycle in order to
complete the removal of cleaning material; this removal of particles generally takes
around 20 minutes, as do each of the wash and rinse cycles in a typical operation,
giving a total overall cycle time in the region of 1 hour.
[00121] The method of the invention has been shown to be successful in the removal
of cleaning material from the cleaned substrate after processing and tests have
indicated particle removal efficacy such that on average < 20 particles per garment
remain in the washload at the end of the bead separation cycle. Generally, this can be
further reduced to an average of < 10 particles per garment and, in optimised cases
wherein a 20 minute separation cycle is employed, an average of < 5 particles per
garment is typically achieved. With drier garments, achieved using higher G forces
during the water extraction stage of the process, this particle per garment figure can be
even further reduced.
[00122] Additionally, it has been demonstrated that re-utilisation of the non-polymeric
and, when used, polymeric particles in the manner described operates well, so that
particles can be satisfactorily re-used in the cleaning procedure, with little deterioration
in performance generally observed with recycled particles.
[00123] The invention will now be illustrated, though without in any way limiting the
scope thereof, by reference to the following examples and associated illustrations.
Examples
Example 1 - Non-polymeric Particles
[00124] Cleaning trials were carried out in order to test the efficacy of two readily
available non-polymeric particulate cleaning materials versus a control with no particles
added (see Table 1 and Figure 1) .
TABLE 1 PARTICULATE CLEANING MATERIALS & CONTROL
[00125] Washes were carried out in a sealed wash rig (a rotatably mounted drum of 50
cm diameter and 70 cm depth, equipped with lifter 10 cm tall) according to the
conditions described in Table 2.
Particle Washload Wash Wash Particle:Cloth WatenCloth Detergent Rinsed
Type Mass Temperature Duration Ratio Ratio (w/w) (g/kg)
(°C) (mins)
(kg) (w/w)
Glass 4.0 Ambient 20 1 : 1 1.2 : 1 30.0 Yes
(20°C)
Steel 4.0 Ambient 20 1 : 1 1.2 : 1 30.0 Yes
(20°C)
None 4.0 Ambient 20 N/A 1.2 : 1 30.0 Yes
(Control)
(20°C)
TABLE 2 WASH CONDITIONS
[00126] The washload comprised 4.0 kg in total, including 1 WFK PCMS-55_05-05x05
professional laundry stain monitor, and 4 SBL-2004 sebum cloths, with the remaining
washload made up with cotton ballast. The detergent used was Procter & Gamble
Professional Ariel® Liquid, at the manufacturer's recommended dosage. At the end of
the 20 minute wash cycle, the load was rinsed in a domestic washing machine (BEKO
WM5120W - standard rinse cycle), and the stain monitors allowed to air dry. Each
wash was repeated twice. The particles were rinsed clean between washes.
[00127] A Konica Minolta CM-3600A spectrophotometer was used to record the CIE
Lab L, a and b colour co-ordinates of the various stains on the WFK PCMS-55_05-
05x05 stain monitor, and these were then used to calculate D E as a measure of the
degree of cleaning achieved versus the unwashed equivalent (the higher the D E value
the better the cleaning). The results are shown in Table 3 (averaged over the repeat
washes), with comments made on the basis that a difference of 1 unit in D E is
discernible by eye.
[00128] As can be seen from Table 3, there is no significant cleaning benefit from using
the glass particles versus the control. There is only 1 stain (10D) giving a positive
result, with 7 at parity performance, and 5 with poorer performance. The steel particles
however, show improvement with 6 stains (10C, 10D, 90RM, 90PB, 10N and 90MF),
whilst parity is achieved for 5 stains, with only 2 showing poorer performance.
TABLE 3 WASH TEST RESULTS
[00129] As the glass and steel particles here are essentially the same size and shape,
5 it is their density (and hence their mass) difference which is the key factor. The higher
density (and mass) of the steel particles obviously increases their mechanical action
and, therefore, cleaning capability. Hence, it can be concluded that there is a threshold
density for a given non-polymeric particle size and shape, to generate enough
mechanical action for the particle to show improved cleaning performance. For the
10 specific non-polymeric particles tested here, it is evident that this threshold is > 3.5
g/cm3 (or, similarly, a particle mass threshold exists at > 190 mg).
Example 2 - Mixtures of Non-polymeric and Polymeric Particles
[00130] Cleaning trials were also carried out to test the efficacy of mixtures of non-
15 polymeric and polymeric particulate cleaning materials, versus the 100% w/w nonpolymeric
and 100% w/w polymeric options and, again, versus a control with
particles added (see Table 4 and Figure 1) .
5 TABLE 4 PARTICULATE CLEANING MATERIALS & CONTROL
[00131] Washes were carried out in a sealed wash rig (a rotatably mounted drum of 50
cm diameter and 70 cm depth, equipped with lifter 10 cm tall) according to the
conditions described in Table 5.
Particle Type Washload Wash Wash Particle:Cloth WatenCloth Detergent Rinsed
Mass Temperature Duration Ratio Ratio (w/w) (g/kg)
(°C) (mins)
(kg) (w/w)
Steel 4.0 Ambient 20 2 : 1 1.2 : 1 30.0 Yes
(20°C)
Polymer 1 4.0 Ambient 20 2 : 1 1.2 : 1 30.0 Yes
(BASF
(20°C)
Ultramid® B36,
Nylon 6)
Polymer 1/ 4.0 Ambient 20 2 : 1 1.2 : 1 30.0 Yes
Steel Mixtures
(20°C)
(w/w)
20%/80%
40%/60%
60%/40%
20%/80%
Polymer 2 4.0 Ambient 20 2 : 1 1.2 : 1 30.0 Yes
(INVISTA
(20°C)
Polyclear®
110 1,
polyethylene
terephthalate)
Polymer 21 4.0 Ambient 20 2 : 1 1.2 : 1 30.0 Yes
Steel Mixtures
(20°C)
(w/w)
20%/80%
40%/60%
60%/40%
20%/80%
None (Control) 4.0 Ambient 20 N/A 1.2 : 1 30.0 Yes
(20°C)
TABLE 5 WASH CONDITIONS
[00132] For the purposes of clarity, it should be pointed out that the particle:cloth ratio
was maintained constant for all of the washes tested. Hence for example, a 20%/80%
polymer/steel particles mixture (w/w), contained 1.6 kg of polymer particles and 6.4 kg
of steel particles (total 8.0 kg, i.e. 2:1 particle:cloth). A 60%/40% polymer/steel particles
mixture (w/w) contained 4.8 kg of polymer particles and 3.2 kg of steel particles, etc.
[00133] The washload comprised 4.0 kg in total, including 1 WFK PCMS-55_05-05x05
professional laundry stain monitor, and 4 SBL-2004 sebum cloths, with the remaining
washload made up with cotton ballast. The detergent used was Procter & Gamble
Professional Ariel® Liquid, at the manufacturer's recommended dosage. At the end of
the 20 minute wash cycle, the load was rinsed in a domestic washing machine (BEKO
WM5120W - standard rinse cycle), and the stain monitors allowed to air dry. Each
wash was repeated twice. The particles were rinsed clean between washes.
[00134] A Konica Minolta CM-3600A spectrophotometer was used to record the CIE
Lab L, a and b colour co-ordinates of the various stains on the WFK PCMS-55_05-
05x05 stain monitor, and these were then used to calculate D E as a measure of the
degree of cleaning achieved versus the unwashed equivalent (the higher the D E value
the better the cleaning). The results are shown in Tables 6(a) & (b) (averaged over the
repeat washes), with comments made on the basis that a difference of 1 unit in D E is
discernible by eye.
WFK Stain Type No Steel Polymer Polymer 1/Steel Polymer Polymer 2/Steel
Stain Particle Particle 1 Mixtures D E 2 Mixtures D E
Monitor D E D E Particle Particle
Coding (Control) D E D E
10C Pigment/lanolin 20%/80% = 12.8 20%/80% = 11.7
on cotton 40%/60% = 11.3 40%/60% = 12.5
60%/40% = 10.1 60%/40% = 11.8
7.3 10.6 9.4 80%/20% = 9.1 11.5 80%/20% = 11.3
20C Pigment/lanolin 20%/80% = 5.7 20%/80% = 4.6
on 40%/60% = 4.9 40%/60% = 6.3
polyester/cotton 60%/40% = 4.6 60%/40% = 4.8
4.7 3.3 4.7 80%/20% =3.9 4.5 80%/20% =4.3
90LI Red wine on 20%/80% = 17.0 20%/80% = 15.7
cotton, aged (IEC 40%/60% = 16.5 40%/60% = 16.8
456) 60%/40% = 15.8 60%/40% = 15.7
17.1 15.9 16.3 80%/20% = 16.1 14.0 80%/20% = 15.3
10D Sebum/pigment 20%/80% = 14. 1 20%/80% = 13.0
on cotton 40%/60% = 11.9 40%/60% = 12.9
60%/40% = 11.9 60%/40% = 12.1
8.5 10.6 11.2 80%/20% = 11.5 11.7 80%/20% = 11.7
20D Sebum/pigment 20%/80% = 17.6 20%/80% = 12.4
on 40%/60% = 14.6 40%/60% = 14.4
polyester/cotton 60%/40% = 12.5 60%/40% = 14.0
11.2 13.0 13.1 80%/20% = 10.3 11.0 80%/20% = 12.0
10U Curry on cotton 20%/80% = 10.4 20%/80% = 9.0
40%/60% = 10.2 40%/60% = 10.6
60%/40% = 9.7 60%/40% = 9.2
9.6 9.9 10.1 80%/20% =8.2 8.9 80%/20% =9.3
10 Motor oil/pigment 20%/80% = 8.0 20%/80% = 7.8
on cotton 40%/60% = 6.8 40%/60% = 6.8
60%/40% = 5.6 60%/40% = 6.9
4.7 5.4 5.6 80%/20% =5.5 7.4 80%/20% =7.3
90R Soot/mineral oil 20%/80% = 10.6 20%/80% = 9.8
on cotton (IEC 40%/60% = 6.8 40%/60% = 8.5
456) 60%/40% = 6.1 60%/40% = 9.8
4.6 4.1 6.8 80%/20% =4.4 7.2 80%/20% =8. 1
90PB Blood on cotton, 20%/80% = 5 1.8 20%/80% = 47. 1
aged 40%/60% = 49.7 40%/60% = 5 .9
(IEC 456) 60%/40% = 50.2 60%/40% = 50. 1
47.8 49.4 5 1.5 80%/20% =42.4 47.3 80%/20% =49.5
10N Egg/pigment on 20%/80% = 22. 1 20%/80% = 17.1
cotton 40%/60% = 18.4 40%/60% = 19.2
60%/40% = 18.6 60%/40% = 20.0
18.8 16.1 17.2 80%/20% = 17.2 18.6 80%/20% =21 .2
10R Starch/pigment on 20%/80% = 7.1 20%/80% = 5.2
cotton 40%/60% = 5.1 40%/60% = 7.3
60%/40% = 3.7 60%/40% = 7.7
4.1 3.3 2.3 80%/20% =3.0 5.3 80%/20% =5.5
10PP Vegetable 20%/80% = 24.2 20%/80% = 15.8
fat/milk/pigment 40%/60% = 14.2 40%/60% = 24.9
on cotton 60%/40% = 16.0 60%/40% = 22.3
9.4 7.7 9.2 80%/20% =6.3 18.9 80%/20% =20.8
90 F Cocoa on cotton, 20%/80% = 13.5 20%/80% = 9.4
aged 40%/60% = 9.7 40%/60% = 13.0
(IEC 456) 60%/40% = 9.6 60%/40% = 11.8
7.6 9.4 7.8 80%/20% =8.2 10.6 80%/20% =7.9
SUM OF ALL D E 20%/80% = 214.9 20%/80% = 178.6
40%/60% = 180. 1 40%/60% = 205. 1
60%/40% = 174.4 60%/40% = 196.2
80%/20% = 80%/20% = 184.2
155.4 158.7 165.2 146. 1 176.9
TABLE 6(a) WASH TEST RESULTS
WFK Stain Stain Type No Steel Polymer Polymer 1/Steel Polymer Polymer 2/Steel
Monitor Particle Particle 1 Mixtures D E - No 2 Mixtures D E - No
Coding D E D E - No Particle Particle D E Particle Particle D E
(Control) Particle D E - No D E - No
D E Particle Particle
D E D E
10C Pigment/lanolin 20%/80% = +5.5 20%/80% = +4.4
on cotton 40%/60% = +4. 1 40%/60% = +5.3
60%/40% = +2.9 60%/40% = +4.5
7.3 +3.3 +2. 1 80%/20% = + 1.8 4.2 80%/20% = +4. 1
20C Pigment/lanolin 20%/80% = + 1.0 20%/80% = < 1
on 40%/60% = < 1 40%/60% = + 1.6
polyester/cotton 60%/40% = < 1 60%/40% = < 1
4.7 - 1.4 < 1 80%/20% = < 1 < 1 80%/20% = < 1
90LI Red wine on 20%/80% = < 1 20%/80% = - 1.4
cotton, aged 40%/60% = < 1 40%/60% = < 1
(IEC 456) 60%/40% = - 1.3 60%/40% = - 1.4
17.1 - 1.2 < 1 80%/20% = - 1.0 -3. 1 80%/20% = - 1.8
10D Sebum/pigment 20%/80% = +5.6 20%/80% = +4.5
on cotton 40%/60% = +3.5 40%/60% = +4.4
60%/40% = +3.4 60%/40% = +3.6
8.5 +2. 1 +2.7 80%/20% = +3.0 +3.2 80%/20% = +3.2
20D Sebum/pigment 20%/80% = +6.3 20%/80% = + 1.2
on 40%/60% = +3.4 40%/60% = +3.2
polyester/cotton 60%/40% = + 1.3 60%/40% = +2.7
11.2 + 1.8 + 1.9 80%/20% = < 1 < 1 80%/20% = < 1
10U Curry on cotton 20%/80% = < 1 20%/80% = < 1
40%/60% = < 1 40%/60% = + 1.0
60%/40% = < 1 60%/40% = < 1
9.6 < 1 < 1 80%/20% = - 1.4 < 1 80%/20% = < 1
10 Motor 20%/80% = +3.3 20%/80% = +3.2
oil/pigment on 40%/60% = +2. 1 40%/60% = +2. 1
cotton 60%/40% = < 1 60%/40% = +2.2
4.7 < 1 < 1 80%/20% = < 1 2.8 80%/20% = +2.6
90R Soot/mineral oil 20%/80% = +6.0 20%/80% = +5.2
on cotton ( IEC 40%/60% = +2.2 40%/60% = +3.9
456) 60%/40% = + 1.5 60%/40% = +5.2
4.6 < 1 +2.2 80%/20% = < 1 2.6 80%/20% = +3.5
90PB Blood on cotton, 20%/80% = +4.0 20%/80% = < 1
aged 40%/60% = + 1.9 40%/60% = +4. 1
(IEC 456) 60%/40% = +2.4 60%/40% = +2.3
47.8 + 1.6 +3.7 80%/20% = -5.4 < 1 80%/20% = + 1.7
10N Egg/pigment on 20%/80% = +3.3 20%/80% = - 1.6
cotton 40%/60% = < 1 40%/60% = < 1
60%/40% = < 1 60%/40% = + 1.2
18.8 -2.7 - 1.6 80%/20% = - 1.6 < 1 80%/20% = +2.5
10R Starch/pigment 20%/80% = +3.0 20%/80% = + 1.1
on cotton 40%/60% = + 1.0 40%/60% = +3.2
60%/40% = < 1 60%/40% = +3.6
4.1 < 1 - 1.8 80%/20% = - 1.1 + 1.2 80%/20% = + 1.4
10PP Vegetable 20%/80% = +14.8 20%/80% = +6.4
fat/milk/pigment 40%/60% = +4.8 40%/60% = + 15.6
on cotton 60%/40% = +6.6 60%/40% = + 13.0
9.4 - 1.7 < 1 80%/20% = -3. 1 +9.5 80%/20% = + 11.4
90 F Cocoa on cotton, 20%/80% = +5.9 20%/80% = + 1.8
aged 40%/60% = +2. 1 40%/60% = +5.4
(IEC 456) 60%/40% = +2.0 60%/40% = +4.2
7.6 + 1.8 < 1 80%/20% = + 1.6 +3.0 80%/20% = < 1
TABLE 6(b) WASH TEST RESULTS
[00135] As can be seen from Tables 6(a) & (b) therefore, the steel particle again shows
cleaning benefit versus the no particle control (improvement with 5 stains - 10C, 10D,
20D, 90PB and 90MF, parity for 4 stains, and 4 with poorer performance). The higher
particle:cloth w/w ratio here has changed the balance of cleaning performance across
the stain range slightly, but overall improvement in cleaning is still evident. The polymer
1 particle also shows cleaning benefit versus the no particle control (improvement with 5
stains - 10C, 10D, 20D, 90RM and 90PB, parity for 6 stains, and 2 with poorer
performance). It is surprising therefore, that the mixture of steel and polymer 1 particles
performs so well across the whole stain range, and not just the stains cleaned well here
by the individual particles alone. If the 20% polymer 1/80% steel particles w/w mixture
is considered for example, the cleaning performance shows improvement on all stains
except 90LI and 10U, which both show parity performance. Indeed, the range of
polymer 1/steel particle mixtures showing benefit over the individual particles can be
seen in Figure 2(a). Here the sum of the DE values for all of the stain types has been
plotted against particle mixture composition (from Table 6(a)). There is clearly a
synergy in mixing these particles beyond what might reasonably be expected given their
individual performances. The line joining the 100% steel particles w/w and 100%
polymer 1 particles w/w data points represents a simple rule of mixtures here, to show
what might be expected. The point at 80% polymer 1/20% steel particles w/w falling
below this line is believed to be an anomaly (see Figure 2(b)).
[00136] This pattern is repeated with the mixture of steel and polymer 2 particles. If the
40% polymer 2/60% steel particles w/w mixture is considered for example, the cleaning
performance shows improvement on all stains except 90LI and 10N, which show parity
performance. The range of polymer 2/steel particle mixtures showing benefit over the
individual particles can be seen in Figure 2(b). Here again, the sum of the DE values for
all of the stain types has been plotted against particle mixture composition (from Table
6(a)). The improvement here is so marked that it would appear all mixtures of these two
particle types show improved cleaning performance versus what might be expected
from the rule of mixtures.
[00137] Throughout the description and claims of this specification, the words
"comprise" and "contain" and variations of them mean "including but not limited to", and
they are not intended to (and do not) exclude other moieties, additives, components,
integers or steps. Throughout the description and claims of this specification, the
singular encompasses the plural unless the context otherwise requires. In particular,
where the indefinite article is used, the specification is to be understood as
contemplating plurality as well as singularity, unless the context requires otherwise.
[00138] Features, integers, characteristics, compounds, chemical moieties or groups
described in conjunction with a particular aspect, embodiment or example of the
invention are to be understood to be applicable to any other aspect, embodiment or
example described herein unless incompatible therewith. All of the features disclosed
in this specification (including any accompanying claims, abstract and drawings), and/or
all of the steps of any method or process so disclosed, may be combined in any
combination, except combinations where at least some of such features and/or steps
are mutually exclusive. The invention is not restricted to the details of any foregoing
embodiments. The invention extends to any novel one, or any novel combination, of
the features disclosed in this specification (including any accompanying claims, abstract
and drawings), or to any novel one, or any novel combination, of the steps of any
method or process so disclosed.
[00139] The reader's attention is directed to all papers and documents which are filed
concurrently with or previous to this specification in connection with this application and
which are open to public inspection with this specification, and the contents of all such
papers and documents are incorporated herein by reference.
CLAIMS
1. A method for the cleaning of a soiled substrate, said method comprising
treating the substrate with a non-polymeric solid particulate cleaning material and wash
water, said treatment being carried out in an apparatus comprising a drum comprising
perforated side walls and having a capacity of between 5 and 50 litres for each kg of
fabric in the washload, wherein said solid particulate cleaning material comprises a
multiplicity of non-polymeric particles at a particle to fabric addition level of 0.1 : - 0: by
mass, each of said particles being substantially cylindrical or spherical in shape and
having an average density in the range of 3.5-12.0 g/cm3 and an average volume in the
range of 5-275 mm3, and wherein said drum comprising perforated side walls is rotated
at a speed which generates G forces in the range of from 0.05 to 900 G.
2. A method as claimed in claim 1 wherein said non-polymeric particles comprise
particles of glass, silica, stone, wood, or any of a variety of metals or ceramic materials.
3. A method as claimed in claim 2 wherein said metal is selected from zinc,
titanium, chromium, manganese, iron, cobalt, nickel, copper, tungsten, aluminium, tin
and lead, and alloys thereof.
4. A method as claimed in claim 2 wherein said ceramic material is selected from
alumina, zirconia, tungsten carbide, silicon carbide and silicon nitride.
5. A method as claimed in any one of claims 1 to 4 wherein said solid particulate
cleaning material additionally comprises a multiplicity of polymeric particles, each of
said particles being substantially cylindrical or spherical in shape and having an
average density in the range of 0.5-2.5 g/cm3 and an average volume in the range of 5-
275 mm3.
6. A method as claimed in claim 5 wherein said polymeric particles comprise
foamed polymeric materials.
7. A method as claimed in claim 5 wherein said polymeric particles comprise
unfoamed polymeric materials.
8. A method as claimed in claim 5, 6 or 7 wherein said polymeric particles
comprise linear polymers.
9. A method as claimed in any one of claims 5 to 8 wherein said polymeric
particles comprise crosslinked polymers.
10. A method as claimed in any one of claims 5 to 9 wherein said polymeric
particles comprise beads of polyalkenes, polyamides, polyesters or polyurethanes.
11. A method as claimed in claim 10 wherein said polyamide comprises Nylon 6 or
Nylon 6,6.
12. A method as claimed in claim 11 wherein said polyamide comprises Nylon 6,6
homopolymer having a molecular weight in the region of from 5000 to 30000 Daltons.
13. A method as claimed in claim 11 wherein said polyester comprises
polyethylene terephthalate or polybutylene terephthalate.
14. A method as claimed in any one of claims 5 to 13 wherein said the ratio of said
non-polymeric particles to said polymeric particles is from 99.9%:0.1% to 0.1%:99.9%.
15. A method as claimed in claim 14 wherein said ratio is from 90.0%: 10.0% to
25.0%:75.0% of non-polymeric particles to polymeric particles.
16. A method as claimed in claim 14 or 15 wherein said ratio is from 85.0%:1 5.0%
to 40.0%:60.0% of non-polymeric particles to polymeric particles.
17. A method as claimed in any preceding claim wherein said particles comprised
in said solid particulate cleaning material are cylindrical and have an oval cross section
wherein the major cross section axis length is in the range of from 2.0-6.0 mm and the
minor cross section axis length is in the range of from 1.3-5.0 mm.
18. A method as claimed in any one of claims 1 to 16 wherein said particles
comprised in said solid particulate cleaning material are cylindrical and have a circular
cross section wherein the cross section diameter is in the range of from 1.3-6.0 mm.
19. A method as claimed in claim 17 or 18 wherein the length of said particles is in
the range of from 1.5-6.0 mm.
20. A method as claimed in any one of claims 1 to 16 wherein said particles
comprised in said solid particulate cleaning material are spherical and the diameter is in
the range of from 2.0-8.0 mm.
2 1. A method as claimed in claim 20 wherein said particles are not perfect spheres
and the diameter is in the range of from 2.2-5.5 mm.
22. A method as claimed in claim 20 wherein said particles are perfect spheres
and the diameter is in the range of from 3.0-7.0 mm.
23. A method as claimed in any preceding claim wherein said solid particulate
cleaning material comprises particles which have a solid structure.
24. A method as claimed in any one of claims 1 to 22 wherein said solid particulate
cleaning material comprises particles which have a hollow structure.
25. A method as claimed in one of claims 1 to 23 wherein said non-polymeric
particles comprise coated non-polymeric particles.
26. A method as claimed in claim 25 wherein said non-polymeric particles
comprise a non-polymeric core material and a shell comprising a coating of a polymeric
material.
27. A method as claimed in claim 26 wherein said core comprises a steel core and
said shell comprises a coating of nylon.
28. A method as claimed in any preceding claim wherein said drum comprising
perforated side walls comprises a rotatably mounted cylindrical cage.
29. A method as claimed in any preceding claim which is carried out at
temperatures not exceeding 95°C.
30. A method as claimed in claim 29 wherein said temperatures do not exceed
75°C.
3 1. A method as claimed in claim 29 or 30 wherein said temperature is in the range
of from 5-40°C.
32. A method as claimed in any preceding claim which additionally comprises
separating the solid particulate cleaning material from the substrate on completion of
the washing process, recovering said solid particulate cleaning material and re-using
said material in subsequent washes.
33. A method as claimed in claim 32 wherein, following separation and recovery,
said solid particulate cleaning material is subjected to a cleaning operation prior to re
use.
34. A method as claimed in any one of claims 28 to 33 wherein said rotatably
mounted cylindrical cage is comprised in a cleaning apparatus comprising a housing
and access means, allowing access to the interior of said cylindrical cage.
35. A method as claimed in any one of claims 28 to 34 wherein said rotatably
mounted cylindrical cage is concentrically located within a rotatably mounted cylindrical
drum having a greater diameter than said cage, wherein said cage and said drum are
concentrically located within a stationary cylindrical drum having a greater diameter than
said rotatably mounted drum, and wherein said rotatably mounted cylindrical cage and
said rotatably mounted cylindrical drum are adapted to rotate independently.
36. A method as claimed in any one of claims 28 to 35 wherein said rotatably
mounted cylindrical cage is mounted in a first chamber within said housing means,
which also comprises a second chamber located adjacent said cylindrical cage.
37. A method as claimed in claim 36 which additionally comprises at least one
recirculation means and a multiplicity of delivery means.
38. A method as claimed in claim 36 or 37 which additionally comprises sealing
means, removably attached to the outer surface of the cylindrical side walls of said
rotatably mounted cylindrical cage, and adapted to prevent the ingress or egress of
fluids and solid particulate matter from the interior of said cage.
39. A method as claimed in claim 36 or 37 which additionally comprises pumping
means, and wherein said rotatably mounted cylindrical cage comprises a drum
comprising perforated side walls, wherein up to 60% of the surface area of said side
walls comprises perforations, and said perforations comprise holes having a diameter of
no greater than 25.0 mm.
40. A method as claimed in any one of claims 34 to 39 wherein said access means
comprises a hinged door mounted in the housing which may be opened to allow access
to the inside of the cylindrical cage and which may be closed in order to provide a
substantially sealed system.
4 1. A method as claimed in any one of claims 28 to 40 wherein said apparatus
comprises circulation means, adapted to promote circulation of said solid particulate
cleaning material.
42. A method as claimed in any one of claims 28 to 4 1 wherein said rotatably
mounted cylindrical cage comprises a 98 cm diameter cage and the speeds of rotation
are in the range of 30-800 rpm.
43. A method as claimed in any preceding claim which comprises performing, in
sequence, the steps of:
(a) washing;
(b) first extraction of excess water;
(c) first separation of particles of solid particulate cleaning material;
(d) rinsing;
(e) second extraction of excess water;
(f) optionally repeating steps (d) and (e) at least once; and
(g) second separation of particles of solid particulate cleaning material.
44. A method as claimed in claim 43 wherein steps (d) and (e) are repeated up to
10 times.
45. A method as claimed in claim 43 or 44 wherein said washing process is carried
out at between 0.05 and 0.95 G, the rinsing water is added under similar conditions,
then extracted at a higher G force of 5.5 to 350 G, and said separation of particles from
the fabric is carried out at 0.05 to 0.95 G.
46. A method as claimed in claim 45 wherein said drum comprising perforated side
walls comprises a rotatably mounted cylindrical cage having a diameter of 98 cm, said
washing process is carried out at a speed of rotation of between 10 and 42 rpm, the
rinsing water is added under similar conditions, then extracted at a speed of rotation of
100-800 rpm, and said separation of the particles from the fabric is carried out at a
speed of rotation of 10-42 rpm.
as claimed in any one of claims 28 to 46 wherein a wash cycle
of:
introducing a solid particulate cleaning material and water into a
second chamber of an apparatus comprising a rotatably
mounted cylindrical cage;
agitating said solid particulate cleaning material and water;
loading at least one soiled substrate into said rotatably mounted
cylindrical cage via access means;
closing the access means so as to provide a substantially sealed
system;
causing the rotatably mounted cylindrical cage to rotate whilst
introducing wash water and any required additional cleaning
agent to uniformly wet out the substrate;
introducing said solid particulate cleaning material and water into
said rotatably mounted cylindrical cage and operating the
apparatus for a wash cycle, wherein said rotatably mounted
cylindrical cage continues to rotate and wherein fluids and solid
particulate cleaning material are caused to fall through
perforations in said rotatably mounted cylindrical cage into a
second chamber in a controlled manner;
operating pumping means so as to transfer fresh solid
particulate cleaning material and recycle used solid particulate
cleaning material to separating means;
operating control means so as to add said fresh and recycled
solid particulate cleaning material to said rotatably mounted
cylindrical cage in a controlled manner; and
continuing with steps (vi), (vii) and (viii) as required to effect
cleaning of the soiled substrate.
48. A method as claimed in any preceding claim wherein at least one additional
cleaning agent is employed.
49. A method as claimed in claim 48 wherein said at least one additional cleaning
agent is pre-mixed with water and added to said drum comprising perforated side walls
via separating means during the introduction of said solid particulate cleaning material
and water into said drum comprising perforated side walls via recirculating means.
50. A method as claimed in claim 48 wherein said at least one additional cleaning
agent is added to said drum comprising perforated side walls via dosing means.
5 1. A method as claimed in claim 50 wherein said dosing means comprises a
fixedly mounted spray nozzle optionally mounted on an access means.
52. A method as claimed in any one of claims 48 to 5 1 wherein said at least one
additional cleaning agent may be added to said drum comprising perforated side walls
in multiple dosing steps during the cleaning operation.
53. A method as claimed in any one of claims 48 to 52 wherein said at least one
additional cleaning agent comprises a detergent composition comprising cleaning
components and post-treatment components.
54. A method as claimed in claim 53 wherein said cleaning components are
selected from surfactants, enzymes and bleach.
55. A method as claimed in claim 53 or 54 wherein said post-treatment
components are selected from components anti-redeposition additives, perfumes and
optical brighteners.
56. A method as claimed in claim 53, 54 or 55 which comprises one or more other
additives selected from builders, chelating agents, dye transfer inhibiting agents,
dispersants, enzyme stabilizers, catalytic materials, bleach activators, polymeric
dispersing agents, clay soil removal agents, suds suppressors, dyes, structure
elasticizing agents, fabric softeners, starches, carriers, hydrotropes, processing aids
and pigments.
57. A method as claimed in any one of claims 43 to 56 which additionally
comprises the addition of treatment agents to the rinse water.
58. A method as claimed in claim 57 wherein said treatment agents are selected
from at least one of fluorescent brighteners, perfumes, softeners and starch.
59. A method as claimed in any preceding claim which is carried out at a wash
water to substrate ratio of between 5.0:1 and 0.1 : 1 w/w.
60. A method as claimed in any preceding claim for use in small or large scale
batchwise processes.
6 1. A cleaning composition comprising a solid particulate cleaning composition and
at least one additional cleaning agent, wherein said solid particulate cleaning material
comprises a multiplicity of non-polymeric particles.
62. A cleaning composition as claimed in claim 6 1 wherein said non-polymeric
particles comprise particles of glass, silica, stone, wood, or any of a variety of metals or
ceramic materials.
63. A cleaning composition as claimed in claim 62 wherein said metal is selected
from zinc, titanium, chromium, manganese, iron, cobalt, nickel, copper, tungsten,
aluminium, tin and lead, and alloys thereof.
64. A cleaning composition as claimed in claim 62 wherein said ceramic material
selected from alumina, zirconia, tungsten carbide, silicon carbide and silicon nitride.
65. A cleaning composition as claimed in any one of claims 6 1 to 63 wherein said
solid particulate cleaning material additionally comprises a multiplicity of polymeric
particles.
66. A cleaning composition as claimed in claim 65 wherein said polymeric particles
comprise foamed or unfoamed polymeric materials.
67. A cleaning composition as claimed in claim 65 or 66 wherein said polymeric
particles comprise linear or crosslinked polymers.
68. A cleaning composition as claimed in claim 65, 66 or 67 wherein said polymeric
particles comprise beads of polyalkenes, polyamides, polyesters or polyurethanes.
69. A cleaning composition as claimed in any one of claims 6 1 to 68 wherein said
at least one additional cleaning agent comprises at least one detergent composition.
70. A cleaning composition as claimed in any one of claims 6 1 to 69 wherein said
solid particulate cleaning material comprises particles which have a solid or a hollow
structure.
7 1. A cleaning composition as claimed in any one of claims 6 1 to 69 wherein said
non-polymeric particles comprise coated non-polymeric particles.
72. A cleaning composition as claimed in claim 7 1 which comprises a nonpolymeric
core material and a shell comprising a coating of a polymeric material.
73. A cleaning composition as claimed in claim 72 wherein said core comprises a
steel core and said shell comprises a coating of nylon.

The invention provides a meth
od for the cleaning of a soiled substrate, the
method comprising treating the substrate with
a non-polymeric solid particulate cleaning ma
terial and wash water, the treatment being car
ried out in an apparatus comprising a drum
comprising perforated side walls and having a
capacity of between 5 and 50 litres for each kg
of fabric in the washload, wherein the solid
particulate cleaning material comprises a mul
tiplicity of non-polymeric particles at a
particle to fabric addition level of 0.1 :1 -10:
by mass, each of the particles being substan
tially cylindrical or spherical in shape, and
wherein the drum comprising perforated side
walls is rotated at a speed which generates G
forces in the range of from 0.05 to 900 G. The
non-polymeric particles may comprise
particles of glass, silica, stone, wood, or any
of a variety of metals or ceramic materials.
Preferably the solid particulate cleaning ma
terial additionally comprises a multiplicity of
polymeric particles each of which is substan
tially cylindrical or spherical in shape. Prefer
ably, at least one detergent is employed in the
cleaning process. The invention provides optimum
cleamng performance as a result of improved mechanical interaction between substrate and cleaning media and is preferably
used for the cleaning of textile fabrics. The method allows for significant reductions in the consumption of detergents, water and en -
ergy when compared with the conventional wet cleaning of textile fabrics, and also facilitates reduced washing-related textile fabric
5 damage. The invention also envisages a cleaning composition comprising a solid particulate cleaning composition and at least one
S additional cleaning agent.