METHODS AND COMPOSITIONS RELATED TO RECYCLING POLYMER WASTE
TECHNICAL FIELD
The present invention is directed to polymer compositions, for example, recycled
polymer compositions, to processes for the production thereof, to functional fillers for
use in said compositions and to articles formed from the polymer compositions.
BACKGROUND
It is known to incorporate inorganic particulate fillers, such as ground inorganic
minerals into polymer compositions for a variety of purposes. Approaches have been
proposed to improve the compatibility of the inorganic filler and the polymer
composition. For example, US-A-7732514 describes a composition comprising a
plastics material, an inorganic particulate solid such as aluminium hydrate and a
coupling surface modifier. In coupling surface modifiers the modifier interacts with both
the surface of the particulate filler and the polymer matrix.
In recent years, the recycling of polymer waste material has come to the fore.
However, the recycling of polymer waste material has presented challenges which are
not necessarily encountered during the preparation of polymer compositions derived
from virgin polymer.
These challenges include the problem of contamination and soiling of the polymer
waste resulting from its original use and during post-use collection and initial
processing. Such contamination can be in the form of volatile and/or solid impurities.
The presence of such contaminants imparts unpleasant odours to the polymer waste
material and, if not properly removed, can adversely affect the quality of the final
recycled polymer. Typically, polymer waste is treated in a single washing step to
remove contaminants.
Further, polymer waste streams often comprise a mixture of different polymer types,
e.g., polyethylene and polypropylene, which can present compatibility problems in
recycled polymers prepared from such mixed polymer waste streams. Conventionally,
therefore, greater focus is placed on the separation of polymers into their constituent
types before further processing. However, such separation is technically arduous and
therefore relatively expensive.
Thus, as the need to recycle polymer waste materials increases, there is a continuing
need for the development of new methods and compositions for the economically
viable processing of polymer waste materials into high quality polymer compositions
and articles.
The present inventors have found new fillers for use in polymer compositions,
particularly polymer compositions derived from post-consumer polymer waste, as well
as new processes for recycling polymer waste materials, which address or at least
ameliorate the aforementioned problems and which also enable the production of low
odour, high quality recycled polymer compositions.
SUMMARY OF THE INVENTION
In accordance with a first aspect of the invention, there is provided a process for
recycling post-consumer polymer waste material comprising:
providing at least one post-consumer waste polymer;
cleaning the post-consumer waste polymer;
providing a functional filler comprising
i . an inorganic particulate; and
ii. a coating comprising a first compound including a terminating propanoic
group or ethylenic group with one or two adjacent carbonyl groups; and
combining the post-consumer waste polymer and the functional filler to form a
recycled polymer.
In accordance with a second aspect of the invention, there is provided a process for
recycling polymer waste material comprising:
providing at least one waste polymer;
cleaning the waste polymer in a first process step;
cleaning the waste polymer in a second process step;
providing a functional filler including
i . an inorganic particulate; and
ii. a coating comprising a compound including a terminating propanoic
group or ethylenic group with one or two adjacent carbonyl groups; and
combining the waste polymer and the functional filler to form a recycled
polymer.
In accordance with a third aspect of the invention, there is provided a process for
recycling polymer waste material comprising:
providing at least one waste polymer;
dry cleaning the waste polymer;
providing a functional filler including
i . an inorganic particulate; and
ii. a coating comprising a compound including a terminating propanoic
group or ethylenic group with one or two adjacent carbonyl groups; and
combining the waste polymer and the functional filler to form a recycled
polymer.
In accordance with a fourth aspect of the present invention, there is provided a
functional filler comprising:
i . an inorganic particulate;
ii. a coating on the surface of the inorganic particulate, wherein the coating
comprises
a first compound including a terminating propanoic group or ethylenic
group with one or two adjacent carbonyl groups; and
a second compound selected from the group consisting of one or more
fatty acids and one or more salts of a fatty acid, and combinations thereof.
In accordance with a fifth aspect, there is provided a polymer composition, comprising:
at least one polymer; and
a functional filler including
i . an inorganic particulate; and
ii. a coating on the surface of the inorganic particulate, wherein the
coating comprises:
a first compound including a terminating propanoic group or
ethylenic group with one or two adjacent carbonyl groups,
with the proviso that when the at least one polymer is not recycled from
polymer waste in accordance with one or other of the processes of the first,
second or third aspects of the present invention, the coating additionally
comprises a second compound selected from the group consisting of
stearic acid and a stearate.
In accordance with a sixth aspect, the present invention is directed to use of a
functional filler as defined in accordance with the first, second or third aspects of the
present invention in a recycled polymer derived from at least one waste polymer,
wherein the at least one waste polymer is cleaned, for example (solvent-free) dry
cleaned, in accordance with the first, second or third aspects of the present invention.
In accordance with a seventh aspect, the present invention is directed to a functional
filler comprising an inorganic particulate; and a coating comprising a first compound
including a terminating propanoic group or ethylenic group with one or two adjacent
carbonyl groups. The inorganic particulate has a d5oof from about 0.5 to about 1.5 mhi .
Optionally the inorganic particulate is ground calcium carbonate. Optionally the first
compound is present in the functional filler in an amount of from about 0.6 to about 1.2
wt. %. The inorganic particulate may have a d50 of from about 0.5 to about 1.0 m h .
In accordance with an eighth aspect, there is provided an article of manufacture formed
from the polymer composition of the fifth aspect of the present invention.
In accordance with a ninth aspect, there is provided a composition comprising at least
one polymer, a functional filler according to fourth or seventh aspects of the present
invention, and optionally a peroxide-containing additive, for example, di-cumyl peroxide
or 1,1-Di(tert-butylperoxy)-3,3,5-trimethylcyclohexane.
In accordance with a tenth aspect, there is provided the use of a functional filler
according to the seventh aspect of the present invention in a polymer composition
(optionally wherein the polymer composition comprises a mixture of at least two
different polymer types) for improving the notched Charpy impact property of a
moulded component formed from the polymer composition. The functional filler is
present in the polymer composition in an amount ranging from about 5% to about 50%
by weight of the polymer composition.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 depicts the particle size distribution of the dry ground and wet ground calcium
carbonates used in Example 1.
Figure 2 is a graph summarizing various tensile properties of compounded materials
comprising the coated wet ground carbonate of Figure 1, as prepared in the Example
1.
Figure 3 is a graph summarizing various tensile properties of compounded polymer
materials comprising the coated dry ground carbonate of Figure 1, as prepared in
Example 1.
Figure 4 is a graph summarizing various unnotched Charpy impact properties of
compounded polymer materials comprising the coated wet ground carbonate of Figure
1, as prepared in the Example 1.
Figure 5 is a graph summarizing various unnotched Charpy impact properties of
compounded polymer materials comprising the coated dry ground carbonate of Figure
1, as prepared in the Example 1.
Figure 6 is graph summarizing flex yield strength of injection moulded test pieces
prepared in accordance with Example 2.
Figure 7 is a graph summarizing flexural modulus of injection moulded test pieces
prepared in accordance with Example 2.
Figure 8 is a graph summarizing notched Charpy peak energy of injection moulded test
pieces prepared in accordance with Example 2
DETAILED DESCRIPTION
Processes of the invention
As stated above, the present invention is directed to processes for recycling polymer
waste, such as post-consumer waste polymer.
Recycling refers to processing materials for use in its original end use purpose or for
other purpose.
In accordance with the first aspect of the invention, there is a provided a process for
recycling post-consumer polymer waste material comprising:
providing at least one post-consumer waste polymer;
cleaning the post-consumer waste polymer;
providing a functional filler comprising
i . an inorganic particulate; and
ii. a coating comprising a first compound including a terminating propanoic
group or ethylenic group with one or two adjacent carbonyl groups; and
combining the post-consumer waste polymer and the functional filler to form a
recycled polymer.
The post-consumer waste polymer is typically shredded, flaked, chipped or granulated
prior to the cleaning step. Processes and apparatus for shredding, flaking, chipping or
granulating polymer waste are well known in the art, as will be readily apparent to one
of ordinary skill in the art.
The cleaning step may comprise washing, with or without float-separation techniques,
the polymer waste to remove engrained dirt and other volatile and solid impurities.
Typically, the polymer waste is washed in a washing tank in the presence of water and
other cleaning additives, such as surfactants, detergents and the like. The polymer
waste material may be mechanically agitated to facilitate the removal of impurities.
Additionally, the polymer waste may be subjected to abrasion during the washing step,
for example, with a brush and the like. An advantage of wet cleaning is that it may
combine density separation and cleaning of mixed polymer waste streams comprising
polyethylene (PE), polypropylene(PP) and other polymer fractions to produce a
separated fraction with a density less than about 1 g/cm3, which would mainly (e.g.,
greater than 90% by weight) contain PE and PP.
In an embodiment, the cleaning comprises dry cleaning the waste polymer to remove
volatile and solid impurities from the waste polymer. Suitable dry cleaning plant
includes a chamber, which may be cylindrical, in which the polymer waste material is
rotated in the presence of a gas and kept in suspension. In an embodiment, the dry
cleaning includes centrifuging the polymer waste material. The gas is preferably
heated above ambient temperature. The temperature may be in the range of 50°C to
200°C, for example, between 50°C and 150 °C. In an embodiment, the gas is hot air.
A person of ordinary skill in the art will be able to determine suitable above ambient
temperatures. The turbulence ensures an excellent drying effect (e.g., a constant
average moisture content of about 2%). Impurities such as sand, soil, paper and fibres
may be separated off by screens and the cleaned material is passed to a material
discharge point for further processing. The impurities may be separated by one or
more melt filters incorporated within the screens. Therefore, in an embodiment, the
process further comprises melt filtering the waste polymer, optionally in a vacuum.
This dry cleaning process is carried out in the absence of added solvent(s) and can
therefore be described as solvent-free dry cleaning. This dry cleaning process is
carried out in the absence of added water or other aqueous liquids.
Through the removal of the volatile or solid impurities, unpleasant odours associated
with such impurities are reduced or eradicated owing, at least in part, to the novel
cleaning steps of the processes of the present invention. Solvent-free dry cleaning is
particularly advantageous as it enables to the production of thoroughly cleaned
polymer waste at relatively low cost compared to, for example, a conventional (wet)
washing step using detergents and the like. Further, because cleaning agents such as
detergents and solvents and the like are not used in the dry cleaning, steps to remove
these cleaning agents prior to further processing are not necessary. Moreover,
because the dry cleaned polymer waste is in a dry state, measures to dry the cleaned
polymer waste prior to further processing are not necessary.
The (solvent-free) dry cleaning of the polymer waste enables a clean, dry and relatively
gentle (compared to conventional wet cleaning processes) process which, with a
relatively short dwell time, enables the production of recycled polymer wastes without
adversely impacting on the quality of the polymer waste.
In another advantageous embodiment, the polymer waste is cleaned in a series of two
or more (solvent-free) dry cleaning steps, as described above. In such an
embodiment, the cleaned material discharged from the first dry cleaning step is
subjected to a second dry cleaning step. This process may further comprise melt
filtering the waste polymer, optionally in a vacuum. This process may further comprise
a first compounding stage in which the dry cleaned polymer waste is combined with the
functional filler and an optional peroxide-containing additive, which is followed by a
second compounding stage in which additional components, for example, slip and/or
process aids and/or mould release agents and/or antioxidants, as described below, are
combined with the composition of the first compounding stage.
In another embodiment, the cleaning step of the first aspect of the invention may
comprise solvent-based dry cleaning. Solvent-based dry cleaning techniques are well
known in the art, as will be readily apparent to one of ordinary skill in the art. Typical
solvents include glycol ethers, hydrocarbon-based solvents, liquid silicone,
perchloroethylene and supercritical C0 2. Supercritical carbon dioxide may used as a
more environmentally friendly solvent as compared to the more traditional solvents
such as hydrocarbons and perchloroethylene. The solvent may include a small amount
of detergent (e.g., 0.5 to 1.5%) to enhance cleaning power. The detergent may be
anionic or cationic. In another embodiment, the clearing process of the first aspect of
the invention does not include solvent-based dry cleaning.
In a further embodiment, the waste polymer, e.g., a post-consumer waste polymer, is
pre-washed prior to dry cleaning the waste polymer.
In accordance with the second aspect of the invention, there is provided a process for
recycling polymer waste material comprising:
providing at least one waste polymer;
cleaning the waste polymer in a first process step;
cleaning the waste polymer in a second process step;
providing a functional filler including
i . an inorganic particulate; and
ii. a coating comprising a compound including a terminating propanoic
group or ethylenic group with one or two adjacent carbonyl groups; and
combining the waste polymer and the functional filler to form a recycled
polymer.
The first and second cleaning steps are described above in connection with the first
aspect of the invention. One or both of the cleaning steps may include solvent-free dry
cleaning as described above in connection with the first aspect of the invention. The
adaption of conventional cleaning protocols by using at least two cleaning steps is
advantageous as it enables the production of relatively cleaner polymer waste streams
which are substantially devoid of volatile and solid impurities which may otherwise
cause unpleasant odours and/or adversely affect the quality of the final recycled
polymer composition.
The first and/or second cleaning process steps may comprise solvent-based dry
cleaning, as described above. Typical solvents include glycol ethers, hydrocarbonbased
solvents, liquid silicone, perchloroethylene and supercritical C0 2. Supercritical
carbon dioxide may used as a more environmentally friendly solvent as compared to
the more traditional solvents such as hydrocarbons and perchloroethylene. The
solvent may include a small amount of detergent (e.g., 0.5 to 1.5%) to enhance
cleaning power. The detergent may be anionic or cationic.
Thus, in embodiments the first and second process steps of the second aspect of the
present invention may comprise either (i) washing, with or without float-separation
techniques, the polymer waste to remove engrained dirt and other volatile and solid
impurities, as described above, (ii) solvent-free dry cleaning, as described above or (iii)
solvent-based dry cleaning, as described above.
In accordance with the third aspect of the invention, there is provided a process for
recycling polymer waste material comprising:
providing at least one waste polymer;
dry cleaning the waste polymer;
providing a functional filler including
i . an inorganic particulate; and
ii. a coating comprising a compound including a terminating propanoic
group or ethylenic group with one or two adjacent carbonyl groups; and
combining the waste polymer and the functional filler to form a recycled
polymer.
The dry cleaning of the waste polymer in accordance with this aspect of the invention is
described above in connection with the first and second aspects of the invention.
Thus, in one embodiment, dry cleaning the waste polymer comprises solvent-free dry
cleaning the waste polymer. In another embodiment, the dry cleaning comprises
solvent-based dry cleaning the waste polymer. In a further embodiment, dry cleaning
the waste polymer comprises solvent-free and solvent-based dry cleaning the waste
polymer in a series of two or more dry cleaning steps. In yet another embodiment, dry
cleaning the polymer waste does not include solvent-based dry cleaning.
In one advantageous embodiment of the first, second and third aspects of the
invention, the waste polymer comprises at least two different polymer types, for
example, at least three different polymer types. For example, the waste polymer
stream may comprise polyethylene (e.g., HDPE) and polypropylene or, for example,
the waste polymer stream may comprise high density polyethylene (HDPE) and low
density polyethylene (LDPE) or, for example, the waste polymer stream may comprise
HDPE, LDPE and polypropylene (as commonly found of recycled municipal waste
streams). The process of the present invention therefore enables the effective and
economical recycling of polymer waste streams without the need to necessarily
separate the polymer waste streams into different polymer types prior to further
processing.
In another embodiment, the at least one waste polymer of the second and third aspects
of the present invention may be post-consumer waste polymer.
An exemplary apparatus for dry cleaning polymer waste in accordance with the present
invention is provided by Maschinen und Anlagenbau Schulz GmbH (see:
http://pdf.directindustrv.com/pdf/m-a-s-maschinen-und-anlagenbau-schulz/drying-andcleaning-
plant/64259-1 471 63.html , the entire contents of which are hereby
incorporated by reference).
Following cleaning, the cleaned polymer waste is combined with a functional filler to
form a recycled polymer. In an embodiment, the functional filler is present in an
amount equal to or greater than about 3 % by weight of the waste polymer, for
example, equal to or greater than about 5 % by weight, for example, equal to or greater
than about 8 % by weight of the waste polymer. In an embodiment, the functional filler
is present in an amount equal to or greater than about 10% by weight of the waste
polymer, for example, equal to or greater than about 20% by weight, for example, equal
to or greater than about 30% by weight, for example, equal to or greater than about
40% by weight, for example, equal to or greater than about 50% by weight or, for
example, equal to or greater than about 60% by weight. In another embodiment, the
functional filler is present in an amount ranging from about 5% to about 70% by weight
of the waste polymer, for example, from about 10% to about 70% by weight of the
waste polymer, for example, from about 5% to about 60 %, for example, from about 5%
to about 50%, for example, from about 5% to about 40%, for example, from about 5%
to about 35% by weight, for example, from about 5% to about 30% by weight, for
example, from about 5% to about 30% by weight, for example, from about 5% to about
25% by weight, for example, from about 5 % to about 20 % by weight, for example,
from about 5% to about 15% by weight, for example, from about 20% to about 70% by
weight, for example, from about 30% to about 70% by weight, for example, from about
40% to about 70% by weight or, for example, from about 50% to about 20% by weight
of the waste polymer. The functional filler may be present in amount less than or equal
to about 80% by weight of the waste polymer, for example, less than or equal to about
70%, for example, less than or equal to about 60%, for example less than or equal to
about 50 % or, for example, less than about 40 % by weight of the waste polymer. The
functional filler is described in detail below. As further described below, in
embodiments, the coating of the functional filler may additionally comprise a second
compound selected from the group consisting of fatty acids and salts of fatty acids, for
example, stearic acid and/or calcium stearate.
In an embodiment, the process further comprises combining the waste polymer and the
functional filler with a peroxide-containing additive. The peroxide-containing additive is
described in detail below.
The combining may comprise compounding in an extruder or in a masterbatch. This
step may be integrated with the cleaning and/or dry cleaning steps. Alternatively, the
cleaned polymer waste material may be transported to a separate location and then
combined with the functional filler and the optional peroxide-containing additive, and
further processed in accordance with the first, second and third aspects of the
invention. Further details of this aspect of the processes of the present invention are
described in detail below under the section entitled 'polymer compositions'.
In an embodiment of the process aspects of the present invention, the process further
comprises combining the cleaned waste polymer and the functional filler with virgin
polymer material (i.e., non-recycled polymer material) prior to forming the recycled
polymer composition.
The functional filler
In accordance with at least the fourth and seventh aspects of the present invention, the
functional filler comprises an inorganic particulate and a coating comprising a first
compound including a terminating propanoic group or ethylenic group with one or two
adjacent carbonyl groups. The purpose of the coating is to improve the compatibility of
the inorganic particulate filler and the polymer matrix with which it is to be combined,
and/or improve the compatibility of two or more different polymers in the recycled
polymer composition by cross-linking or grafting the different polymers. In recycled
polymer compositions comprising recycled and virgin polymer, the functional filler
coating may serve to cross-link or graft the different polymers.
In other aspects and embodiments of the present invention, the coating additionally
comprises a second compound selected from the group consisting of one or more fatty
acids and one or more salts of fatty acids, for example, stearic acid or calcium
stearate.
The inorganic particulate material
The inorganic particulate material may, for example, be an alkaline earth metal
carbonate or sulphate, such as calcium carbonate, magnesium carbonate, dolomite,
gypsum, a hydrous kandite clay such as kaolin, halloysite or ball clay, an anhydrous
(calcined) kandite clay such as metakaolin or fully calcined kaolin, talc, mica, perlite or
diatomaceous earth, or magnesium hydroxide, or aluminium trihydrate, or combinations
thereof.
A preferred inorganic particulate material for use in the method according to the first
aspect of the present invention is calcium carbonate. Hereafter, the invention may tend
to be discussed in terms of calcium carbonate, and in relation to aspects where the
calcium carbonate is processed and/or treated. The invention should not be construed
as being limited to such embodiments.
The particulate calcium carbonate used in the present invention may be obtained from
a natural source by grinding. Ground calcium carbonate (GCC) is typically obtained by
crushing and then grinding a mineral source such as chalk, marble or limestone, which
may be followed by a particle size classification step, in order to obtain a product
having the desired degree of fineness. Other techniques such as bleaching, flotation
and magnetic separation may also be used to obtain a product having the desired
degree of fineness and/or colour. The particulate solid material may be ground
autogenously, i.e. by attrition between the particles of the solid material themselves, or,
alternatively, in the presence of a particulate grinding medium comprising particles of a
different material from the calcium carbonate to be ground. These processes may be
carried out with or without the presence of a dispersant and biocides, which may be
added at any stage of the process.
Precipitated calcium carbonate (PCC) may be used as the source of particulate
calcium carbonate in the present invention, and may be produced by any of the known
methods available in the art. TAPPI Monograph Series No 30, "Paper Coating
Pigments", pages 34-35 describes the three main commercial processes for preparing
precipitated calcium carbonate which is suitable for use in preparing products for use in
the paper industry, but may also be used in the practice of the present invention. In all
three processes, a calcium carbonate feed material, such as limestone, is first calcined
to produce quicklime, and the quicklime is then slaked in water to yield calcium
hydroxide or milk of lime. In the first process, the milk of lime is directly carbonated
with carbon dioxide gas. This process has the advantage that no by-product is formed,
and it is relatively easy to control the properties and purity of the calcium carbonate
product. In the second process the milk of lime is contacted with soda ash to produce,
by double decomposition, a precipitate of calcium carbonate and a solution of sodium
hydroxide. The sodium hydroxide may be substantially completely separated from the
calcium carbonate if this process is used commercially. In the third main commercial
process the milk of lime is first contacted with ammonium chloride to give a calcium
chloride solution and ammonia gas. The calcium chloride solution is then contacted
with soda ash to produce by double decomposition precipitated calcium carbonate and
a solution of sodium chloride. The crystals can be produced in a variety of different
shapes and sizes, depending on the specific reaction process that is used. The three
main forms of PCC crystals are aragonite, rhombohedral and scalenohedral, all of
which are suitable for use in the present invention, including mixtures thereof.
Wet grinding of calcium carbonate involves the formation of an aqueous suspension of
the calcium carbonate which may then be ground, optionally in the presence of a
suitable dispersing agent. Reference may be made to, for example, EP-A-614948 (the
contents of which are incorporated by reference in their entirety) for more information
regarding the wet grinding of calcium carbonate.
In some circumstances, additions of other minerals may be included, for example, one
or more of kaolin, calcined kaolin, wollastonite, bauxite, talc, titanium dioxide or mica,
could also be present.
When the inorganic particulate material of the present invention is obtained from
naturally occurring sources, it may be that some mineral impurities will contaminate the
ground material. For example, naturally occurring calcium carbonate can be present in
association with other minerals. Thus, in some embodiments, the inorganic particulate
material includes an amount of impurities. In general, however, the inorganic
particulate material used in the invention will contain less than about 5% by weight,
preferably less than about 1% by weight, of other mineral impurities.
Unless otherwise stated, particle size properties referred to herein for the inorganic
particulate materials are as measured by the well known conventional method
employed in the art of laser light scattering, using a CILAS 1064 instrument (or by other
methods which give essentially the same result). In the laser light scattering technique,
the size of particles in powders, suspensions and emulsions may be measured using
the diffraction of a laser beam, based on an application of Mie theory. Such a machine
provides measurements and a plot of the cumulative percentage by volume of particles
having a size, referred to in the art as the 'equivalent spherical diameter' (e.s.d), less
than given e.s.d values. The mean particle size d50 is the value determined in this way
of the particle e.s.d at which there are 50% by volume of the particles which have an
equivalent spherical diameter less than that d50 value. The term d90 is the particle size
value less than which there are 90% by volume of the particles.
The d50 of the inorganic particulate may be less than about 100 m h , for example, less
than about 80 m h for example, less than about 60 m h for example, less than about 40
/jm, for example, less than about 20 m h , for example, less than about 15 m h , for
example, less than about 10 m h , for example, less than about 8 m h , for example, less
than about 6 m h , for example, less than about 5 m h , for example, less than about 4, for
example, less than about 3 m h , for example less than about 2 m h , for example, less
than about 1.5 m h or, for example, less than about 1 m h . The d50 of the inorganic
particulate may be greater than about 0.5 m h , for example, greater than about 0.75 m h
greater than about 1 m h , for example, greater than about 1.25 m h or, for example,
greater than about 1.5 m h . The d50 of the inorganic particulate may be in the range of
from 0.5 to 20 m h , for example, from about 0.5 to 10 m h , for example, from about 1 to
about 5 m h , for example, from about 1 to about 3 m h , for example, from about 1 to
about 2 m h , for example, from about 0.5 to about 2 m h or, for example, from about 0.5
to 1.5 m h , for example, from about 0.5 to about 1.4 m h , for example, from about 0.5 to
about 1.4 m h , for example, from about 0.5 to about 1.3 m h , for example, from about 0.5
to about 1.2 /jm, for example, from about 0.5 to about 1. 1 m, for example, from about
0.5 to about 1.0 m h , for example, from about 0.6 to about 1.0 m h , for example, from
about 0.7 to about 1.0 mhi , for example about 0.6 to about 0.9 mhi , for example, from
about 0.7 to about 0.9 mhi .
The d90 (also referred to as the top cut) of the inorganic particulate may be less than
about 150 m h , for example, less than about 125 m h for example, less than about 100
m h for example, less than about 75 m h , for example, less than about 50 m h , for
example, less than about 25 m h , for example, less than about 20 m h , for example, less
than about 15 m h , for example, less than about 10 m h , for example, less than about 8
m h , for example, less than about 6 m h , for example, less than about 4 m h , for
example, less than about 3 m h or, for example, less than about 2 m h . Advantageously,
the d90 may be less than about 25 m h .
The amount of particles smaller than 0.1 m h is typically no more than about 5% by
volume.
The inorganic particulate may have a particle steepness equal to or greater than about
10. Particle steepness (i.e., the steepness of the particle size distribution of the
inorganic particulate) is determined by the following formula:
Steepness = 100 x (d3o d 7o) ,
wherein d30 is the value of the particle e.s.d at which there are 30% by volume of the
particles which have an e.s.d less than that d30 value and d70 is the value of the particle
e.s.d. at which there are 70% by volume of the particles which have an e.s.d. less that
that d7o value.
The inorganic particulate may have a particle steepness equal to or less than about
100. The inorganic particulate may have a particle steepness equal to or less than
about 75, or equal to or less than about 50, or equal to or less than about 40, or equal
to or less than about 30. The inorganic particulate may have a particle steepness from
about 10 to about 50, or from about 10 to about 40.
The inorganic particulate is coated with a coupling modifier.
The coating
The coati ng com prises a com pou nd including a term inati ng propa noic grou p or
ethylenic group with one or two adjacent carbonyl groups (also referred to herein as a
coupling modifier).
In one embodiment, the coupling modifier has a formula ( 1 ) :
A-(X-Y-CO)m(0-B-CO) OH ( 1 )
wherein
A is a moiety containing a terminating ethylenic bond with one or two adjacent
carbonyl groups;
X is O and m is 1 to 4 or X is N and m is 1;
Y is C -18-alkylene or C2 - i 8-alkenylene;
B is C2 -6-alkylene; n is 0 to 5;
provided that when A contains two carbonyl groups adjacent to the ethylenic group, X
is N.
In an embodiment, A-X- is the residue of acrylic acid , optionally wherein (0-B-CO) n is
the residue of d -valerolactone or e-caprolactone or a mixture thereof, and optionally
wherein n is zero.
In another embodiment, A-X- is the residue of maleimide, optionally wherein (0-B-CO) n
is the residue of d -valerolactone or e-caprolactone or a mixture thereof, and optionally
wherein n is zero.
Specific examples of coupling modifiers are b-carboxy ethylacrylate, b-
carboxyhexylmaleimide, 10-carboxydecylmaleimide and 5-carboxy pentyl maleimide.
Exemplary coupling modifiers and there methods of preparation are described in US-A-
773251 4, the entire contents of which is hereby incorporated by reference.
In another embodiment, the coupling modifier is b-acryloyloxypropanoic aci d or an
oligomeric acrylic acid of the formula (2):
CH2=CH-COO[CH2-CH2-COO] H (2)
wherein n represents a number from 1 to 6.
In an embodiment, n is 1, or 2, or 3, or 4, or 5, or 6.
The oligomeric acrylic acid of formula (2) may be prepared by heating acrylic acid in
the presence of 0.001 to 1% by weight of a polymerization inhibitor, optionally under
elevated pressure and in the presence of an inert solvent, to a temperature in the range
from about 50°C to 200°C. Exemplary coupling modifiers and there methods of
preparation are described in US-A-4267365, the entire contents of which is hereby
incorporated by reference.
In another embodiment, the coupling modifier is b-acryloyloxypropanoic acid. This
species and its method of manufacture is described in US-A-3888912, the entire
contents of which is hereby incorporated by reference.
The coupling modifier is present in the functional filler in an amount effective to achieve
the desired result. This will vary between coupling modifiers and may depend upon the
precise composition of the inorganic particulate. For example, the coupling modifier
may be present in an amount equal to or less than about 5 wt. % based on the total
weight of the functional filler, for example equal to or less than about 2 wt. % or, for
example equal to or less than about 1.5 wt. %. In an embodiment, the coupling
modifier is present in the functional filler in an amount equal to or less than about 1.2
wt.% based on the total weight of the functional filler, for example equal to or less than
about 1. 1 wt. %, for example equal to or less than about 1.0 wt. %, for example, equal
to or less than about 0.9 wt. %, for example equal to or less than about 0.8 wt. %, for
example equal to or less than about 0.7 wt. %, for example, less than or equal to about
0.6 wt. %, for example equal to or less than about 0.5 wt %, for example equal to or
less than about 0.4 wt. %, for example equal to or less than about 0.3 wt. %, for
example equal to or less than about 0.2 wt. % or, for example less than about 0.1 wt.
%. Typically, the coupling modifier is present in the functional filler in an amount
greater than about 0.05 wt. %. In further embodiments, the coupling modifier is present
in the functional filler in an amount ranging from about 0.1 to 2 wt. % or, for example,
from about 0.2 to about 1.8 wt. %, or from about 0.3 to about 1.6 wt. %, or from about
0.4 to about 1.4 wt. %, or from about 0.5 to about 1.3 wt. %, or from about 0.6 to about
1.2 wt. %, or from about 0.7 to about 1.2 wt. %, or from about 0.8 to about 1.2 wt. %, or
from about 0.8 to about 1. 1 wt. %.
In further aspects (.e.g., the fourth aspect) and embodiments of the present invention,
the coating additionally comprises a second compound selected from the group
consisting of one or more fatty acids and one or more salts of fatty acids, and
combinations thereof.
In an embodiment, the one or more fatty acids is selected from the group consisting of
lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid,
lignoceric acid, cerotic acid, myristoleic acid, palmitoleic acid, sapienic acid, oleic acid,
elaidic acid, vaccenic acid, linoleic acid, linoelaidic acid, a-linolenic acid, arachidonic
acid, eicosapentaenoic, erucic acid, docosahexaenoic acid and combinations thereof.
In another embodiment, the one or more fatty acids is a saturated fatty acid or an
unsaturated fatty acid. In another embodiment, the fatty acid is a C12-C24 fatty acid, for
example, a C16-C22 fatty acid, which may be saturated or unstarurated. In one
embodiment, the one or more fatty acids is stearic acid, optionally in combination with
other fatty acids.
In another embodiment, the one or more salts of a fatty acid is a metal salt of the
aforementioned fatty acids. The metal may be an alkali metal or an alkaline earth
metal or zinc. In one embodiment, the second compound is calcium stearate.
The second compound, when present, is present in the functional filler in an amount
effective to achieve the desired result. This will vary between coupling modifiers and
may depend upon the precise composition of the inorganic particulate. For example,
the second compound may be present in an amount equal to or less than about 5 wt.
% based on the total weight of the functional filler, for example equal to or less than
about 2 wt. % or, for example equal to or less than about 1 wt. %. In an embodiment,
the, second compound is present in the functional filler in an amount equal to or less
than about 0.9 wt.% based on the total weight of the functional filler, for example equal
to or less than about 0.8 wt. %, for example equal to or less than about 0.7 wt. %, for
example, less than or equal to about 0.6 wt. %, for example equal to or less than about
0.5 wt %, for example equal to or less than about 0.4 wt. %, for example equal to or
less than about 0.3 wt. %, for example equal to or less than about 0.2 wt. % or, for
example equal to or less than about 0.1 wt. %. Typically, the second compound, if
present, is present in the functional filler in an amount greater than about 0.05 wt. %.
The weight ratio of the coupling modifier to the second compound may be from about
5:1 to about 1:5, for example, from about 4:1 to about 1:4, for example, from about 3:1
to about 1:3, for example, from about 2:1 to about 1:2 or, for example, about 1: 1 . The
amount of coating, comprising the first compound (i.e., the coupling modifier) and the
second compound (i.e., the one more fatty acids or salts thereof), may be an amount
which is calculated to provide a monolayer coverage on the surface of the inorganic
particulate. In embodiments, the weight ratio of the first compound to the second
compound is from about 4:1 to about 1:3, for example from about 4:1 to about 1:2, for
example from about 4:1 to about 1: 1 , for example from about 4:1 to about 2:1 , for
example, from about 3.5:1 to about 1: 1 , for example from about 3.5:1 to 2:1 or, for
example, from about 3.5:1 to about 2.5:1
The addition of the second compound means that the amount of the first compound,
which is relatively expensive compared to the second compound, can be reduced,
therefore enabling the production of polymer compositions at reduced cost without
adversely affecting the compatibility enhancing effect of the coupling modifier and/or
the mechanical properties of the filled polymer composition. The partial replacement of
the first compound with the second compound, for example, stearic acid, may
advantageously lead to an improvement in one or more mechanical properties of the
filled polymer or, in other embodiments, enable the formulator to modify one or more
mechanical properties of the filled polymer depending on, for example, the amount of
the second compound included in the filler to partially replace the first compound. The
one or more mechanical properties may be selected from the following tensile
properties: Elongation at Yield (%), Elongation at Break (%), Yield Stress (MPa) and
Stress at Break (MPa). The one or more mechanical properties may be selected from
the following unnotched Charpy impact properties: Peak Force (N), Peak Deflection
(mm) and Peak Energy (J). These properties may be measured in accordance with the
methods described below.
The coating may additionally comprise a peroxide-containing additive. In an
embodiment, the peroxide-containing additive comprises di-cumyl peroxide or 1,1-
Di(tert-butylperoxy)-3,3,5-trimethylcyclohexane. The peroxide-containing additive may
not necessarily be included with the coating and instead may be added during the
compounding of the functional filler and the polymer, as described below. In some
polymer systems, e.g., HDPE, the inclusion of a peroxide-containing additive may
promote cross-linking of the polymer chains. In other polymer systems, e.g.,
polypropylene, the inclusion of a peroxide-containing additive may promote polymer
chain scission. The peroxide-containing additive may be present in the functional filler
in amount effective to achieve the desired result. This will vary between coupling
modifiers and may depend upon the precise composition of the inorganic particulate
and the polymer. For example, the peroxide-containing additive may be present in an
amount equal to or less than about 1 wt. % based on the weight of the polymer in the
polymer composition to which the peroxide-containing additive is to be added, for
example, equal to or less than about 0.5 wt. %, for example, 0.1 wt %, for example
equal to or less than about 0.09 wt. %, or for example equal to or less than about 0.08
wt. % or for example, equal to or less than about 0.06 wt. %. Typically, the peroxidecontaining
additive, if present, is present in an amount greater than about 0.01 wt. %
based on the weight of the polymer.
The functional filler may be prepared by combining the inorganic particulate, coating
compound(s) and optional peroxide-containing additive and mixing using conventional
methods, for example, using a Steele and Cowlishaw high intensity mixer, preferably at
a temperature equal to or less than 80°C. The coating compound(s) may be applied
after grinding the inorganic particulate, but before the inorganic particulate is added to
the optionally recycled polymer composition. For example, the coating compound(s)
may be added to the inorganic particulate in a step in which the inorganic particulate is
mechanically de-aggregated. Coating compounds may be applied during deaggregation
carried out in a milling machine, such as a laboratory scale mill, which may
be carried out for a suitable time period, for example about 300 seconds.
According to another aspect, the present invention is directed to the use of a functional
filler as defined in accordance with the first, second or third aspects of the present
invention in a recycled polymer derived from at least one waste polymer, wherein the at
least one waste polymer is cleaned in accordance with the first, second or third aspects
of the present invention. In an embodiment, the at least one waste polymer is postconsumer
polymer waste. For example, the post-consumer polymer waste may be a
mixture of polyethylene (e.g., HDPE) and polypropylene (PP) or, for example, a mixture
of HDPE and LDPE or, for example, a mixture of HDPE, LDPE and PP. In one
embodiment, the post-consumer polymer waste may include polymer from multiple
sources (i.e., supply streams) and from 90% to 100% polyethylene and polypropylene.
In an embodiment of this aspect of the invention, the at least one waste polymer may
comprise a mixture of at least two different polymer types or at least three different
polymer types selected from linear low density polyethylene (LLDPE) and medium
density grades thereof, high density polyethylene (HDPE), low density polyethylene
(LDPE), polypropylene (PP) and polystyrene.
In another embodiment, the recycled polymer is solvent-free dry cleaned in accordance
with the first, second or third aspects of the present invention.
Optional additional filler components
The functional filler according to the present invention may contain one or more
secondary filler components, if desired. Such additional components, where present,
are suitably selected from known filler components for polymer compositions. For
example, the inorganic particulate used in the functional filler may be used in
conjunction with one more other known secondary filler components, such as for
example, titanium dioxide, carbon black and talc. Additional secondary fillers are
advantageously used in specific applications, such as for example in the preparation of
garbage bags. When a secondary filler component is used the inorganic particulate is
preferably present in the functional filler in an amount of at least 80% of the total dry
weight of the mixed inorganic particulate and secondary filler component.
The functional filler may additionally comprise an antioxidant. Suitable antioxidants
include, but are not limited to, organic molecules consisting of hindered phenol and
amine derivatives, organic molecules consisting of phosphates and lower molecular
weight hindered phenols, and thioesters. Exemplary antioxidants include Irganox 1010
and Irganox 215, and blends of Irganox 1010 and Irganox 215.
Polymer compositions
As stated above, the present invention is directed to a polymer composition comprising
at least one polymer and a functional filler. The functional filler comprises an inorganic
particulate and a coating comprising a compound including a terminating propanoic
group or ethylenic group with one or two adjacent carbonyl groups, as described
above. The functional filler may be included, for example, as a compatibility modifier.
In embodiments in which the at least one polymer is not recycled from polymer waste
in accordance with the first, second or third aspects of the invention, the coating
additionally comprises a second compound selected from the group consisting of one
or more fatty acids and one or more salts of a fatty acid, for example, stearic acid
and/or calcium stearate, as described above. In other embodiments, regardless of the
derivation of the at least one polymer, the functional filler additionally comprises a
second compound selected from the group consisting of one or more fatty acids and
one or more salts of a fatty acid, for example, stearic acid and/or calcium stearate.
As described above, the functional filler may be present in an amount equal to or
greater than about 10% by weight of the polymer, for example, equal to or greater than
about 20% by weight, for example, equal to or greater than about 30% by weight, for
example, equal to or greater than about 40% by weight, for example, equal to or
greater than about 50% by weight or, for example, equal to or greater than about 60%
by weight. In another embodiment, the functional filler is present in an amount ranging
from about 10% to about 70% by weight of the polymer, for example, from about 20%
to about 70% by weight, for example, from about 30% to about 70% by weight, for
example, from about 40% to about 70% by weight or, for example, from about 50% to
about 20% by weight of the polymer. The functional filler may be present in amount
less than or equal to about 80% by weight of the polymer, for example, less than or
equal to about 70%, for example, less than or equal to about 60%, for example less
than or equal to about 50 % or, for example, less than about 40 % by weight of the
polymer.
The coupling modifier of the functional filler, preferably the compound of formula ( 1)
above, may be present in the polymer compositions or recycled polymer compositions
of the present invention in an amount of from about 0.01 % by weight to about 4 % by
weight, based on the total weight of the polymer and functional filler, for example, from
about 0.02 % by weight to about 3.5 % by weight, for example from about 0.05 % by
weight to about 1.4 % by weight, for example, from about 0.1 % by weight to about 0.7
% by weight, for example from about 0.15 % by weight to about 0.7 % by weight, for
example from about 0.3 % by weight to about 0.7 % by weight, for example from about
0.5 % by weight to about 0.7 % by weight, for example from about 0.02 by weight to
about 0.5 %, for example, from about 0.05 % by weight to about 0.5 % by weight, for
example from about 0.1 % by weight to about 0.5 % by weight, for example from about
0.15 % by weight to about 0.5 % by weight, for example from about 0.2 % by weight
about 0.5 % by weight or, for example from about 0.3 % by weight to about 0.5 % by
weight.
The polymers which may be used in accordance with the invention are advantageously
thermoplastic polymers. Thermoplastic polymers are those which soften under the
action of heat and harden again to their original characteristics on cooling, that is, the
heating-cooling cycle is fully reversible. By conventional definition, thermoplastics are
straight and branched linear chain organic polymers with a molecular bond. Examples
of polymers which may be used in accordance with the invention include, but are not
limited to, linear low density polyethylene (LLDPE) and medium density grades thereof,
high density polyethylene (HDPE), low density polyethylene (LDPE), polypropylene
(PP), polyethylene terephthalate (PET), vinyl/polyvinyl cholride (PVC), polystyrene, and
mixtures thereof. In one embodiment, the polymer is not PET or PVC.
As stated above, aspects of the present invention are directed to recycled polymer
compositions. Thus, polymers used in accordance with the invention are waste
polymers, including all of the different types of polymer stated above. The polymer
waste may include a mixture of different types of polymer, for example, a mixture of
polyethylene and polypropylene. Types of waste polymer include post-consumer
waste polymer, post-industrial waste polymer and post-agricultural waste polymer.
Advantageously, the waste polymer used in accordance with the present invention may
be post-consumer waste polymer.
Post-consumer waste (or post-use) includes but is not limited to material generated by
end-users of products that has fulfilled its intended purpose or can no longer be used
such as material returned from within the distribution chain; post-industrial waste
includes but is not limited to material generated by industrial or manufacturing uses;
agricultural waste includes but is not limited to material used in growing plants (e.g.,
trees, flowers, herbs, bushes, grasses, vines, ferns, mosses, and green algae) and
which may contain organic matter; and mixed polymer wastes (or co-mingled plastics)
includes but is not limited to material consisting of different types of plastic or polymer.
Consumer products made from polyethylene terephthalate (PET) include soda and
water bottles and waterproof packaging. Recycled PET may be used in textiles or to
make bottles.
Consumer products made from HPDE include milk and detergent bottles, toys and
plastic bags. Uses for recycled HDPE include plastic pipes, plastic lumber, flower pots
and rubbish bins.
Consumer products made from LDPE and LLDPE include plastic (grocery) bags, shrink
wrap and films. Uses for recycled LDPE and LLDPE are plastic rubbish bags, grocery
sacks, plastic tubing, agricultural film and plastic lumber.
Consumer products made from polypropylene include refrigerated containers, bags,
bottle tops, carpets and some food wraps.
Consumer products made from polystyrene include non-reusable utensils, meat
packing and protective packaging.
The functional filler described above may be incorporated into a polymer composition,
from which polymer articles may be made of. In an embodiment, the polymer is
derived from polymer waste which has been recycled in accordance with one or more
of the processes of the present invention. If a peroxide-containing additive is not
included with the functional filler it may be added during the compounding process. In
some embodiments, the peroxide-containing additive may be provided in the form of a
masterbatch. In further embodiments, a peroxide-containing additive is not present.
Preparation of the polymer and recycled polymer compositions of the present invention
can be accomplished by any suitable mixing method known in the art, as will be readily
apparent to one of ordinary skill in the art.
Such methods include compounding and extrusion. Compounding may be carried out
using a twin screw compounder, for example, a Baker Perkins 25 mm twin screw
compounder. The polymer, functional filler and optional peroxide containing additive
may be premixed and fed from a single hopper. The resulting melt may be cooled, for
example, in a water bath, and then pelletized. Test pieces, e.g., Charpy bars or tensile
dumbbells, may be injection moulded or cast or blown into film.
The compounded compositions may further comprise additional components, such as
slip aids (for example Erucamide), process aids (for example Polybatch® AMF-705),
mould release agents and antioxidants. Suitable mould release agents will be readily
apparent to one of ordinary skill in the art, and include fatty acids, and zinc, calcium,
magnesium and lithium salts of fatty acids and organic phosphate esters. Specific
examples are stearic acid, zinc stearate, calcium stearate, magnesium stearate, lithium
stearate, calcium oleate and zinc palmitate. Typically, slip and process aids, and
mould release agents are added in an amount less than about 5 wt. % based on the
weight of the masterbatch. Polymer articles, including those described above, may
then be extruded, compression moulded or injected moulded using conventional
techniques known in the art, as will be readily apparent to one of ordinary skill in the
art. Thus, the present invention is also directed to articles formed from the polymer or
recycled polymer compositions of the present invention.
In an advantageous embodiment, the polymer composition is a recycled polymer
obtainable by one or other of the processes of the first, second and third aspects of the
invention. Advantageously, the polymer composition is a recycled polymer obtainable
by one or other of the process of the present invention which comprises a solvent-free
dry cleaning step. In an embodiment, the recycled polymer composition is substantially
devoid of volatile or solid impurities, owing, at least in part, to the novel cleaning steps
of the processes of the present invention. Through the removal of the volatile or solid
impurities, unpleasant odours associated with such impurities are reduced or
eradicated.
Further, in accordance with the first, second, third and fifth aspects of the present and
embodiments thereof in which the waste polymer comprises at least two different
polymer types, for example, polyethylene (e.g., HDPE) and polypropylene or, for
example, HDPE and LDPE or, for example, HDPE, LDPE and PP, the compatibility of
the at least two different polymers may be improved as exhibited by benefit in one or
more mechanical properties, even at filler loading levels of 50% by weight or greater.
Further, without wishing to be bound by theory, it is believed that the cleaning of the
polymer waste material in accordance with the present invention, particularly solventfree
dry cleaning of the polymer waste, possibly resulting from the relatively gentle dry
cleaning process to remove impurities, contributes to the attainment of recycled
polymer waste materials having improved compatibility and mechanical properties.
Thus, the present invention enables processing of mixed polymer waste streams
without the need to separate the mixed polymer waste, e.g., via conventional floatseparation
techniques, into different polymer types.
The recycled polymer, optionally comprising at least two types of different polymer,
may have a notched charpy impact peak energy equal to or greater than the same
polymer that is a virgin polymer. Notched Charpy impact properties may be measured
using a Rosand Instrumented Falling Weight Impact Tester Type 5 using a method
similar to ISO 179, specimen type 1, edgewise impact, 2mm v notch and impact speed
of 2.9 m/s, and a test temperature equal to 23°C.
Unnotched Charpy impact properties may be measured using a Rosand IFW type 5
impact test machine at -20°C. A Charpy impact jig (ISO 179) is fitted to the Rosand
instrument, and interpretation of the force/displacement curve is carried out as detailed
in ISO 6603.
The recycled polymer, optionally comprising at least two types of different polymer,
may have a tensile strength equal to or greater than the same polymer that is a virgin
polymer. Tensile strength may be measured according to ISO 527 using a Hounsfield
HK10S tensometer.
The polymer composition or recycled polymer composition comprising the functional
filler according to the fourth aspect of the present invention and embodiments thereof,
optionally comprising at least two types of different polymer, may have one or more
tensile properties or one or more unnotched Charpy impact properties, as described
above, which is comparable to or improved compared to the same polymer
composition or recycled polymer composition comprising a coated filler which does not
comprise both of the first and second compounds of the functional filler of the fourth
aspect of the present invention.
Thus, in a further embodiment, the present invention is directed to the use of the
functional filler of the fourth aspect of the present invention for maintaining or improving
one or more tensile properties of a polymer composition, for example a recycled
polymer composition, optionally comprising at least two types of polymer composition,
compared to the same polymer composition or recycled polymer composition which
does not comprise both of the first and second compounds of the functional filler of the
fourth aspect of the invention.
Thus, in a further embodiment, the present invention is directed to the use of the
functional filler of the fourth aspect of the present invention for maintaining or improving
one or more unnotched Charpy impact properties of a polymer composition, for
example a recycled polymer composition, optionally comprising at least two types of
polymer composition, compared to the same polymer composition or recycled polymer
composition which does not comprise both of the first and second compounds of the
functional filler of the fourth aspect of the invention.
In the embodiments described immediately above directed to the use of the functional
filler of the fourth aspect of the present invention, the weight ratio of the first compound
(i.e., the coupling modifier) to the second compound (i.e., the one more fatty acids or
salts thereof) may be from about 4:1 to about 1: 1 , for example, from about 4:1 to about
2:1 , or any other weight ratio, or range of weight ratios, described above. In a further
embodiment, the coupling modifier is a coupling modifier of formula ( 1) and the one or
more fatty acids or salts thereof is stearic acid.
In the embodiment described immediately above directed to the use of the functional
filler of the fourth aspect of the present invention, the polymer composition is a recycled
polymer composition, optionally comprising at least two types of different polymers,
which has been solvent-free dry cleaned, in accordance with the first, second or third
aspects of the present invention.
The recycled polymer, optionally comprising at least two types of different polymer,
may have a flexural modulus equal to or greater than the same polymer that is a virgin
polymer. Flexural modulus may be measured according to ISO 178 using a Tinius
Olsen universal test machine with a cross-head speed of 2 mm/min, and a span of 64
mm.
The articles which may be formed from the polymer compositions and recycled polymer
compositions are many and various. In one embodiment, the recycled polymer
composition is suitable for industrial uses such as film uses and piping uses.
Thus, in accordance with the eighth and ninth aspects of the present invention, there is
provided articles of manufacture formed from the polymer composition of the fifth
aspect of the present invention and embodiments thereof.
In accordance with the ninth aspect of the present invention, there is provided articles
of manufacture formed from a polymer composition comprising at least one polymer
(as described herein), a functional filler according to the fourth aspect of the present
invention (as described herein) or a functional filler according to the seventh aspect of
the present invention (as described herein).
The polymer composition from which the article is formed may further comprise a
peroxide-containing additive (as described herein), for example, di-cumyl peroxide or
1,1-Di(tert-butylperoxy)-3,3,5-trimethylcyclohexane. The peroxide-containing additive
is present in the coating of the functional filler.
Advantageously, the functional filler is that according to the seventh aspect of the
present invention.
In a further embodiment, the functional filler of the fourth or seventh aspect of the
present invention, particular the functional filler of the seventh aspect of the present
invention, is present in the polymer composition in an amount of from about 5% to
about 50% by weight of the polymer composition, for example, from about 5% to about
30% by weight of the polymer composition, or from about 5% to about 25 %, or from
about 5% to about 20 % by weight, or from about 5% to about 15% by weight.
Articles of manufacture include injected moulded or extruded components such as, for
example, industrial, commercial and residential piping and tubing, including
underground water and sewage pipes, surface ground water piping, cable protection
piping, piping for plumbing, and guttering for buildings, for example, commercial or
residential buildings.
In this respect, it has surprisingly been found that in certain embodiments, the use of
the functional filler of the seventh aspect of the present invention, in a polymer
composition (optionally wherein the polymer composition comprises a mixture of at
least two different polymer types) improves notched Charpy impact property of a
moulded component formed from the polymer composition. In advantageous
embodiments, the functional filler is present in the polymer composition in an amount
ranging from about 5% to about 50%, for example, from about 5% to about 30% by
weight of the polymer composition. The polymer composition may comprise a mixture
of least two different polymer types, for example, polyethylene (e.g., HDPE) and
polypropylene or, for example, HDPE and LDPE or, for example, HDPE, LDPE and PP.
Further, it has been unexpectedly found that functional filler compositions according to
embodiments of the present invention, for example, those comprising inorganic
particulate having a d5o of greater than or equal to about 1.3 mhi , incorporated into
polymer compositions which are formed into moulded components, may prevent,
reduce or ameliorate naturally occurring post-moulding shrinkage of the moulded
component, for example, piping or tubing. This may cause difficulties when filled piping
is used together with unfilled piping components, such as connecting collars. Thus, in
certain embodiments of the seventh aspect of the present invention in which the
inorganic particulate has a d5o of less than about 1.3 mhi , for example, equal to or less
than about 1.0 m h , the functional filler may be used in a polymer composition formed
into a moulded component in an amount to control naturally occurring post-moulding
shrinkage of the moulded component, for example, to obviate retardation of naturally
occurring post-moulding shrinkage. Conversely, function filler according to certain
embodiments of the present invention comprising inorganic particulate having a d50 of
greater than or equal to about 1.3 m h , for example, greater than or equal to about 1.2
mhi , or about 1. 1 mhi , or about 1.0 mhi , may be used in a in a polymer composition
formed into a moulded component to ameliorate, reduce or prevent naturally occurring
post-moulding shrinkage of the moulded component.
In certain embodiments, the moulded component is injection moulded
In such embodiments, the polymer composition may be a recycled polymer
composition derived from at least one waste polymer. The at least one polymer may
be cleaned, for example, solvent-free dry cleaned, in accordance with any one of the
first, second or third aspects of the present invention. The at least one waste polymer
may comprise a mixture of at least two different polymer types.
For the avoidance of doubt, the present application is directed to the subject-matter
described in the following numbered paragraphs:
1. A process for recycling post-consumer polymer waste material comprising:
providing at least one post-consumer waste polymer;
cleaning the post-consumer waste polymer;
providing a functional filler comprising:
i . an inorganic particulate; and
ii. a coating comprising a first compound including a terminating
propanoic group or ethylenic group with one or two adjacent carbonyl groups; and
combining the post-consumer waste polymer and the functional filler to form a
recycled polymer.
2. A process for recycling polymer waste material comprising:
providing at least one waste polymer;
cleaning the waste polymer in a first process step;
cleaning the waste polymer in a second process step;
providing a functional filler including
i . an inorganic particulate; and
ii. a coating comprising a first compound including a terminating
propanoic group or ethylenic group with one or two adjacent carbonyl groups; and
combining the waste polymer and the functional filler to form a recycled polymer.
3. The process of paragraph 1 or 2, wherein the cleaning comprises dry cleaning
including centrifuging the waste polymer in a gas to remove volatile and/or solid
impurities from the waste polymer.
4. A process for recycling polymer waste material comprising:
providing at least one waste polymer;
dry cleaning the waste polymer;
providing a functional filler including:
i . an inorganic particulate; and
ii. a coating comprising a first compound including a terminating
propanoic group or ethylenic group with one or two adjacent carbonyl groups; and
combining the waste polymer and the functional filler to form a recycled polymer.
5. The process of paragraph 4, wherein the dry cleaning includes centrifuging the
waste polymer in a gas to remove volatile and solid impurities from the waste polymer.
6. The process of any one of paragraphs 1-5, further comprising melt filtering the
waste polymer.
7. The process of any one of paragraphs 3-6, further comprising washing the waste
polymer prior to dry cleaning the waste polymer.
8. The process of any one of paragraphs 1-7, wherein the waste polymer comprises
at least two different polymers, for example, polyethylene and polypropylene.
9. The process of paragraph 1, wherein the functional filler is present in an amount
ranging from about 50% to about 70% by weight of the waste polymer.
10. The process of paragraphs 1, 2 or 4, wherein the step of combing comprises
compounding in an extruder or in a masterbatch.
11. The process of paragraphs 1, 2 or 4, further comprising combining the waste
polymer and the functional filler with a peroxide-containing additive to form a recycled
polymer.
12. A process accord ing to any preceding numbered paragraph , further comprising
com bining the waste polymer and the functiona l f iller with virgin polymer prior to
forming the recycled polymer.
13. A process according to any preceding numbered paragraph, wherein the coating
additionally comprises a second compound selected from one or more fatty acids and
one more salts of a fatty acid, for example, stearic acid and/or calcium stearate.
14. A functional filler comprising:
i . an inorganic particulate; and
ii. a coating on the surface of the inorganic particulate, wherein the
coating comprises:
a first compound including a terminating propanoic group or ethylenic group
with one or two adjacent carbonyl groups; and
a second compound selected from the group consisting of one or more fatty
acids and one or more salts of a fatty acid , for example, stearic acid and/or calcium
stearate.
15. The functional filler of paragraph 14, wherein the first compound has a formula
( 1 ) :
A-(X-Y-CO)m(0-B-CO) OH ( 1 )
wherein
A is a moiety containing a terminating ethylenic bond with one or two adjacent carbonyl
groups;
X is O and m is 1 to 4 or X is N and m is 1;
Y is C -18-alkylene or C2 - i 8-alkenylene;
B is C2 -6-alkylene; n is 0 to 5;
provided that when A contains two carbonyl groups adjacent to the ethylenic group, X
is N.
15. The functional filler of paragraph 14, wherein the first compound comprises b-
acryloyloxypropanoic acid or an oligomeric acrylic acid of the formula (2):
CH2=CH-COO[CH2-CH2-COO] H (2)
wherein n represents a number from 1 to 6.
16. The functional filler of any one of paragraphs 14-16, wherein the coating further
comprises a peroxide-containing additive, for example, di-cumyl peroxide or 1,1-Di(tertbutylperoxy)-
3,3,5-trimethylcyclohexane.
17. The functional filler of paragraph 14, wherein the first and/or second compound is
present in an amount less than 0.6 wt.% of the inorganic particulate.
18. A polymer composition, comprising:
at least one polymer; and
a functional filler including
i . an inorganic particulate; and
ii. a coating on the surface of the inorganic particulate, wherein the
coating comprises:
a first compound including a terminating propanoic group or ethylenic group
with one or two adjacent carbonyl groups,
with the proviso that when the at least one polymer is not recycled from polymer
waste in accordance with any one of paragraphs 1-13, the coating additionally
comprises a second compound selected from the group consisting of one or more fatty
acids and one more salts of a fatty acid, for example, stearic acid and/or calcium
stearate.
19. The composition of paragraph 19, wherein the coating comprises a second
compound selected from the group consisting of one or more fatty acids and one more
salts of a fatty acid, for example, stearic acid and/or calcium stearate.
20. A recycled polymer composition, obtainable by the process of any one of
paragraphs 1-13.
2 1. The composition of any one of paragraphs 19-21 , wherein the composition is a
masterbatch.
22. The composition of paragraph 22, wherein the composition further comprises a
peroxide-containing additive, for example, di-cumyl peroxide or 1,1-Di(tert-butylperoxy)-
3,3,5-trimethylcyclohexane, optionally wherein the peroxide-containing additive is
present in the coating.
23. The composition of paragraph 19, comprising at least one waste polymer,
optionally wherein the at least one polymer comprises a mixture of at least two different
polymer types or at least three polymer types.
24. The composition according to any one of paragraphs 19-25, wherein the
functional filler is present in an amount ranging from about 50% to about 70% by
weight of the polymer or recycled polymer composition.
25. The composition of any one of paragraphs 19-25, wherein the composition is
suitable for industrial uses such as film uses and piping uses.
26. The composition of any one of paragraphs 19-25, wherein the composition is a
recycled polymer composition and has a notched charpy peak energy equal to or
greater than the same polymer that is a virgin polymer.
27. The use of a functional filler as defined in any one of paragraphs 1, 2 or 4 in a
recycled polymer composition derived from at least one waste polymer, wherein the at
least one polymer is cleaned, for example, (solvent-free) dry cleaned, in accordance
with any one of paragraphs 1-7, optionally wherein the at least one waste polymer
comprises a mixture of at least two different polymer types or at least three different
polymer types.
The invention will now be illustrated, by reference to the following non-limiting
examples.
EXAMPLES
Example 1
A dry ground calcium carbonate (designated RLO 8154) with a d50 of 2.2 m h and
having the particle size distribution depicted in Figure 1 was coated with a coupling
modifier according to formula ( 1) above and stearic acid.
A wet ground calcium carbonate (designated RLO 8155) with a d50 of 1.6 m h and
having the particle size distribution depicted in Figure 1 was coated a coupling modifier
according to formula ( 1 ) above and stearic acid.
The amount of surface treatment applied was calculated to give monolayer coverage
on the surface.
RLO 8154 was coated with 0.47 Wt.% stearic acid or 0.4 Wt.% coupling modifier; RLO
8155 was coated with 0.9 Wt. % stearic acid or 0.6 Wt. % coupling modifier.
Intermediate coatings of (weight ratio) 25:75, 50:50 and 75:25 stearic acidxoupling
modifier were also prepared.
The minerals were dried overnight in an oven at 80°C, and then coated using a Steele
and Cowlishaw high intensity mixer heated to 80°C. Stearic acid was added to the
mineral and the mixer run at 3000 r.p.m. for five minutes. The coupling modifier was
then added to the mixer and run for a further 5 minutes.
The surface treated minerals were dried overnight before compounding into a
municipal floatation product (principally composed of LDPE and LLDPE and containing
a small amount of PP). After the coating process and immediately before
compounding a peroxide (di-cumyl peroxide), at 0.06% on the filler, was tumble mixed
into the filler.
Compounds, 50 wt % treated with the coated calcium carbonates were prepared using
a Baker Perkins 25 mm twin screw compounder (see Table 1 below):
Table 1.
Charpy bars and tensile dumb-bells were injection moulded using an Arburg Allrounder
injection moulder (see Table 2 below):
Table 2.
After conditioning the moulded test pieces for a minimum of 5 days at 23 °C, the
samples were tested for tensile and Charpy impact properties.
Tensile properties were measured using a Hounsfield HK10S tensometer following ISO
527.
Impact properties were measured using a Rosand IFW type 5 impact test machine at -
20°C. A Charpy impact jig (ISO 179) was fitted to the Rosand instrument, and
interpretation of the force/displacement curve was carried out as detailed in ISO 6603.
Mechanical properties of the filled municipal products are summarized in Figures 2-5.
In the graphs depicted in each of Figures 2-5, the x-axis shows the specific surface
treatment. Thus 100% means a monolayer coverage and 75:25 means 75% of the
monolayer dose for one chemical and 25% of the monolayer dose for the second
chemical.
Example 2
Samples of uncoated filler ((i) a wet ground calcium carbonate with a d50 of 0.8 m h and
having a surface area of about 9 m2/g), and (ii) a wet ground calcium carbonate with a
d50 of 1.3 m h and having a surface area of about 5 m2/g) were dried overnight at 50 °C.
Coating (with a coupling modifier according to formula ( 1 ) above) was carried out using
a Steele and Cowlishaw mixer heated to 40°C for 10 minutes. For each material 1.5 kg
of mineral was placed in the mixer, and a quantity (see Table 5) of coupling modifier
was injected into the mixer after the motor was started. . After coating, the fillers were
placed in an oven at 30°C until needed.
Compounds were prepared using a blend of 75% HDPE:25% PP. Filler loadings of 10,
30 and 50 wt% were used. Dicumyl peroxide was added at 0.06 wt% on the polymer,
and a sterically hindered phenolic antioxidant added at 0.1 wt%.
Compounds were prepared using a Coperion ZSK 18 twin-screw compounder, dried
under vacuum at 50°C overnight, and then injection moulded using an Arburg 320M
injection moulder. Operating conditions are shown in Table 3.
Table 3.
After conditioning for a minimum of five days at 23°C/55% relative humidity, samples
were tested for flexural properties, unnotched Charpy impact properties at -20 °C, and
notched Charpy impact properties. Test methods are shown in Table 4.
Table 4.
Results are summarized in Table 5 below and Figures 6-8.
Table 5.
Unnotched Charpy at -20 °C Number of Test Pieces that Did Not Fail
Loading (Wt%) filler (i) + filler (ii) +
0.6 wt% coupling modifier 1. 1 wt% coupling modifier
0 0 0
10 0 11
20 8 9
30 0 0
CLAIMS
A process for recycling post-consumer polymer waste material comprising:
providing at least one post-consumer waste polymer;
cleaning the post-consumer waste polymer;
providing a functional filler comprising:
i . an inorganic particulate; and
ii. a coating comprising a first compound including a
terminating propanoic group or ethylenic group with one or
two adjacent carbonyl groups; and
combining the post-consumer waste polymer and the functional filler to
form a recycled polymer.
A process for recycling polymer waste material comprising:
providing at least one waste polymer;
cleaning the waste polymer in a first process step;
cleaning the waste polymer in a second process step;
providing a functional filler including
i . an inorganic particulate; and
ii. a coating comprising a first compound including a
terminating propanoic group or ethylenic group with one or two
adjacent carbonyl groups; and
combining the waste polymer and the functional filler to form a recycled
polymer.
A process for recycling polymer waste material comprising:
providing at least one waste polymer;
dry cleaning the waste polymer;
providing a functional filler including:
i . an inorganic particulate; and
ii. a coating comprising a first compound including a
terminating propanoic group or ethylenic group with one or
two adjacent carbonyl groups; and
combining the waste polymer and the functional filler to form a recycled
polymer.
The process of claim 3, wherein the dry cleaning includes centrifuging the waste
polymer in a gas to remove volatile and solid impurities from the waste polymer.
The process of any one of claims 1-4, wherein the waste polymer comprises at
least two different polymers, for example, polyethylene and polypropylene.
The process of claim 1 or any one of claims 2-5, wherein the functional filler is
present in an amount ranging from about 50% to about 70% by weight of the
waste polymer.
The process according to any preceding claim, wherein the functional filler is
present in an amount ranging from about 5% to about 50% by weight of the
waste polymer.
The process according to any preceding claim, wherein the inorganic particulate
has a d50 of from about 0.5 to about 1.0 m h , optionally wherein the inorganic
particulate is ground calcium carbonate, and optionally wherein the first
compound is present in the functional filler in an amount of from about 0.6 to
about 1.2 wt. %..
The process of claims 1, 2 or 3, further comprising combining the waste
polymer and the functional filler with a peroxide-containing additive and/or an
antioxidant to form a recycled polymer.
A process according to any preceding claim, wherein the coating additionally
comprises a second compound selected from one or more fatty acids and one
or more salts of a fatty acid, and combinations thereof.and.
A functional filler comprising:
i . an inorganic particulate; and
ii. a coating on the surface of the inorganic particulate, wherein the coating
comprises:
a first compound including a terminating propanoic group or ethylenic
group with one or two adjacent carbonyl groups; and
a second compound selected from the group consisting of one or more
fatty acids and one or more salts of a fatty acid, and combinations thereof.
The functional filler of claim 11, wherein the coating further comprises a
peroxide-containing additive, for example, di-cumyl peroxide or 1,1-Di(tertbutylperoxy)-
3,3,5-trimethylcyclohexane.
The functional filler of claim 11 or 12, wherein the inorganic particulate has a d50
of from about 0.5 to about 1.0 m h , optionally wherein the inorganic particulate is
ground calcium carbonate, and optionally wherein the first compound is present
in the functional filler in an amount of from about 0.6 to about 1.2 wt. %.
A polymer composition, comprising:
at least one polymer; and
a functional filler including
i . an inorganic particulate; and
ii. a coating on the surface of the inorganic particulate, wherein the
coating comprises:
a first compound including a terminating propanoic group or
ethylenic group with one or two adjacent carbonyl groups,
with the proviso that when the at least one polymer is not recycled from
polymer waste in accordance with any one of claims 1-7, the coating
additionally comprises a second compound selected from the group
consisting of one or more fatty acids and one or more salts of a fatty
acid, and combinations thereof.
A recycled polymer composition, obtainable by the process of any one of claims
1-8.
The composition of claim 15, wherein the composition further comprises a
peroxide-containing additive, for example, di-cumyl peroxide or 1,1-Di(tertbutylperoxy)-
3,3,5-trimethylcyclohexane, optionally wherein the peroxidecontaining
additive is present in the coating.
The composition according to any one of claims 14-16, wherein the functional
filler is present in an amount ranging from about 50% to about 70% by weight of
the polymer or recycled polymer composition.
18. The composition according to any one of claims 14-16, wherein the functional
filler is present in an amount ranging from about 5% to about 50% by weight of
the polymer or recycled polymer composition.
19. The composition according to claim 18, wherein the inorganic particulate has a
d50 of from about 0.5 to about 1.0 m h , optionally wherein the inorganic particulate
is ground calcium carbonate, and optionally wherein the first compound is
present in the functional filler in an amount of from about 0.6 to about 1.2 wt. %.
20. A functional filler comprising:
i . an inorganic particulate; and
ii. a coating comprising a first compound including a terminating propanoic
group or ethylenic group with one or two adjacent carbonyl groups;
wherein the inorganic particulate has a d50 of from about 0.5 to about 1.5
m h , optionally wherein the inorganic particulate is ground calcium
carbonate, and optionally wherein the first compound is present in the
functional filler in an amount of from about 0.6 to about 1.2 wt. %.
2 1. The functional filler of claim 20, wherein the inorganic particulate has a d50 of
from about 0.5 to about 1.0 m h .
22. The use of a functional filler as defined in any one of claims 1, 2 or 3 in a
recycled polymer composition derived from at least one waste polymer, wherein
the at least one polymer is cleaned, for example, solvent-free dry cleaned, in
accordance with any one of claims 1-4, optionally wherein the at least one waste
polymer comprises a mixture of at least two different polymer types..
23. Use of a functional filler according to claim 22 for maintaining or improving (i) one
or more unnotched Charpy impact properties or (ii) one or more tensile properties
of a polymer composition, for example a recycled polymer composition, optionally
comprising at least two types of polymer composition, compared to the same
polymer composition or recycled polymer composition which does not comprise
both of the first and second compounds of the functional filler of claim 2 1.
24. An article of manufacture formed from the polymer composition of any one of
claims 14-19.
An article of manufacture formed from a polymer composition comprising at
least one polymer, a functional filler according to any one of claims 11-13, 20 or
2 1, and optionally a peroxide-containing additive, for example, di-cumyl
peroxide or 1,1-Di(tert-butylperoxy)-3,3,5-trimethylcyclohexane, optionally
wherein the peroxide-containing additive is present in the coating.
An article of manufacture according to claim 25, wherein the polymer
composition comprises a functional filler according to claim 20 or 2 1, and
wherein the functional filler is present in an amount ranging from about 5% to
about 50% by weight of the polymer composition
An article of manufacture according to claim 26, wherein the functional filler is
present in an amount ranging from about 5% to about 30% by weight of the
polymer composition.
An article of manufacture according to any one of claims 24-27, wherein the
article is a pipe or tubing.
A polymer composition, optionally wherein the polymer composition comprises
a mixture of at least two different polymer types, comprising a functional filler
according to claim 20 or 2 1, wherein the functional filler is present in the
polymer composition in an amount ranging from about 5% to about 50% by
weight of the polymer composition, said polymer composition having a first
notched Charpy peak energy greater than a second notched Charpy peak
energy of the polymer composition devoid of the functional filler.
Use of a functional filler according to claim 20 or 2 1 in a polymer composition,
optionally wherein the polymer composition comprises a mixture of at least two
different polymer types, for improving a notched Charpy impact property of a
moulded component formed from the polymer composition, wherein the
functional filler is present in the polymer composition in an amount ranging from
about 5% to about 50% by weight of the polymer composition.
Use according to claim 30, wherein the functional filler is present in the polymer
composition in an amount ranging from about 5% to about 30% by weight of the
polymer composition.
Use according to claims 30 or 3 1 wherein the use of the functional filler in said
amount does not ameliorate, reduce or prevent post-moulding shrinkage of the
moulded component.
Use according to claim 32, wherein the moulded component is injection
moulded.
34. Use according to claim 32 or 33, wherein the moulded component is a pipe or
tubing.
35. Use according to any one of claims 30-34, wherein the polymer composition is a
recycled polymer composition derived from at least one waste polymer, wherein
the at least one polymer is cleaned, for example, solvent-free dry cleaned, in
accordance with any one of claims 1-4, optionally wherein the at least one
waste polymer comprises a mixture of at least two different polymer types.