TECHNICAL FIELD
5
The present invention relates generally to an inorganic particulate material (for example
an alkali earth metal carbonate such as calcium carbonate) suitable for use in
polymeric compositions, for example polymeric films, which may have high mineral
loading. The present invention further relates to compositions comprising the inorganic
10 particulate material, in particular polymers such as polymeric films comprising the
inorganic particulate material. The present invention also relates to the use of the
inorganic particulate material in polymeric compositions such as polymeric film and
methods of making polymeric compositions such as polymeric films comprising the
inorganic particulate material. Certain embodiments of the present invention relate to
15 breathable polymeric films (e.g. films that allow the transmission of gas and vapours).
BACKGROUND OF THE INVENTION
Inorganic particulate materials such as calcium carbonate are used for numerous
20 applications. One such use is the use in polymer compositions. The inorganic
particulate material may be used as a filler (e.g. to reduce the amount of polymer
required in the composition, for example to reduce the cost of the composition), or may
affect the properties of the polymer.
25 For example, inorganic particulate materials may be used in polymeric films. Such
films, porous or non-porous, are manufactured for a number of consumer products
such as garbage bags, backing materials or outer covers on diapers, bandages,
training pants, sanitary napkins, surgical drapes and surgical gowns. Polymeric films
comprising polymer, inorganic particulate material and optional additives such as
30 bonding or tackifying agent(s) may be formed by mixing (e.g. compounding) these
components and then forming the resultant composition into a film layer using any one
of a variety of film-producing processes known to those of ordinary skill in the art (e.g.
by casting, blowing or extrusion). If the film is to be a porous, breathable film, the film
2
can be stretched, uniaxially or biaxially, by any of the well-known techniques in the art
including hydraulics, pinch rolls moving at different rates and tentering.
The nature and amount of the inorganic particulate material used in a polymeric film
5 may influence the properties of the film, for example pore size (and therefore degree of
breathability), strength, thickness and flexibility. The nature of the inorganic particulate
material can also influence how easily and quickly the film can be processed.
Decreasing the particle size of the inorganic particulate material may allow thinner films
to be produced. However, this may cause issues with rheology of the polymeric melts
10 and processing the polymeric films, for example increasing the running time. For
example, decreasing the particle size of the inorganic particulate material may result in
increased tension to be applied to the melt as it emerges from the die, which may, for
example, increase the likelihood of developing holes in the melt.
15 Decreasing the particle size of the inorganic particulate material may also cause
processing issues in the formation of other polymer products such as polymer fibres,
for example by increasing the viscosity of a polymer melt (e.g. at high filler loadings).
For example, swelling of the polymer melt as it emerges from a spinarette, causing a
build-up of material on the die which may create drips and failure of the non-woven
20 fibre web.
Incorporating the inorganic particulate material into the polymeric film, in particular at
high loading levels and/or into thin films, may result in the inorganic particulate material
being liberated from the film and being deposited on the film surface (“dusting”). This
25 may, for example, be detrimental to the post-production conversion process, for
example during the printing or lamination of the films to other structures (e.g. during the
production of diapers).
It is therefore desirable to provide alternative and/or improved inorganic particulate
30 materials that are suitable for use in polymer compositions such as polymeric films
SUMMARY OF THE INVENTION
3
In accordance with a first aspect of the present invention there is provided an inorganic
particulate material (a) having a d98 of less than about 11 μm or less than about 8 μm;
and/or (b) comprising equal to or more than about 3 ppm of particles having a particle
size equal to or greater than about 40 μm; and/or (c) comprising equal to or less than
5 about 40 wt% of particles smaller than about 0.75 μm.
Thus, in a further aspect of the present invention there is provided an inorganic
particulate material having a d98 of less than about 11 μm or less than about 8 μm and
comprising equal to or more than about 3 ppm of particles having a particle size equal
10 to or greater than about 40 μm.
Thus, in a further aspect of the present invention there is provided an inorganic
particulate material comprising equal to or more than about 3 ppm of particles having a
particle size equal to or greater than about 40 μm and equal to or less than about 40
15 wt% of particles smaller than about 0.75 μm.
Thus, in a further aspect of the present invention there is provided an inorganic
particulate material having a d98 of less than about 11 μm or less than about 8 μm and
comprising equal to or less than about 40 wt% of particles smaller than about 0.75 μm.
20
In certain embodiments, the inorganic particulate material has not undergone dry
sieving or sifting. Thus, in a further aspect of the present invention there is provided an
inorganic particulate material having a d98 of less than about 11 μm or equal to or less
than about 8 μm, wherein the inorganic particulate material has not undergone a dry
25 sieving or sifting.
In certain embodiments, the inorganic particulate material comprises equal to or more
than about 3 ppm of particles having a particle size equal to or greater than about 25
μm. Thus, in a further aspect of the present invention there is provided an inorganic
30 particulate material having a d98 of less than about 11μm or equal to or less than about
8 μm and comprising equal to or more than about 3 ppm of particles having a particle
size equal to or greater than about 3 ppm.
4
In accordance with a second aspect of the present invention there is provided a
composition comprising an inorganic particulate material according to any aspect or
embodiment of the present invention.
5 In accordance with a third aspect of the present invention there is provided a
composition comprising a polymer and an inorganic particulate material according to
any aspect or embodiment of the present invention. In certain embodiments, the
composition may be a polymeric film (e.g. lamination coating such as LDPE lamination
coating) or synthetic paper or raffia.
10
In accordance with a fourth aspect of the present invention there is provided a
polymeric film comprising a polymer and an inorganic particulate material according to
any aspect or embodiment of the present invention.
15 In accordance with a fifth aspect of the present invention there is provided a use of an
inorganic particulate material according to any aspect or embodiment of the present
invention in a polymer composition such as a polymeric film (e.g. lamination coating
such as LDPE lamination coating), synthetic paper or raffia.
20 In accordance with a sixth aspect of the present invention there is provided a method
for making a polymeric film, the method comprising:
mixing (e.g. compounding) a polymer and an inorganic particulate material
according to any aspect or embodiment of the present invention; and
shaping the compounded material into a film.
25
In accordance with a seventh aspect of the present invention there is provided a use of
an inorganic particulate material according to any aspect or embodiment of the present
invention as a cavitation agent.
30 In accordance with an eighth aspect of the present invention there is provided a use of
an inorganic particulate material according to any aspect or embodiment of the present
invention in a polymeric film to reduce liberation of inorganic particulate material from
the polymeric film and/or reduce deposition of inorganic particulate material on the
polymeric film surface (dusting). This may, for example, be in comparison to a
5
polymeric film that is identical except that it does not comprise the inorganic particulate
material according to any aspect or embodiment of the present invention.
In certain embodiments of any aspect of the present invention, the inorganic particulate
5 material comprises equal to or greater than about 3 ppm of particles having a particle
size equal to or greater than about 25 μm.
In certain embodiments of any aspect of the present invention, the inorganic particulate
material comprises equal to or greater than about 3 ppm of particles having a particle
10 size equal to or greater than about 40 μm.
In certain embodiments of any aspect of the present invention, the inorganic particulate
material comprises equal to or less than about 40 wt% of particles smaller than about
0.75 μm.
15
In certain embodiments of any aspect of the present invention, the inorganic particulate
material has a d98 equal to or less than about 11 μm or equal to or less than about 8
μm.
20 In certain embodiments of any aspect of the present invention, the inorganic particulate
material has not undergone dry sieving or sifting.
In certain embodiments of any aspect of the present invention, the inorganic particulate
material is an alkali earth metal carbonate such as calcium carbonate. In certain
25 embodiments of any aspect of the present invention, the inorganic particulate material
has a d50 ranging from about 0.5 μm to about 3 μm. In certain embodiments of any
aspect of the present invention, the inorganic particulate material has a d50 ranging
from about 0.5 μm to about 2.5 μm.
30 In certain embodiments of any aspect of the present invention, the polymer
composition is a polymeric film (e.g. lamination coating such as LDPE lamination
coating). In certain embodiments of any aspect of the present invention, the polymeric
film is breathable.
6
Certain embodiments of the present invention may provide one or more of the following
advantages:
• reduce the average particle size of the particulate material;
5 • reduce the % of ultra-fine particles (particles smaller than 0.75 μm) in the
inorganic particulate material;
• reduce the d98 top-cut of the inorganic particulate material;
• increase the steepness of the particle size distribution;
• increase the % of very coarse particles (e.g. larger than 20 μm);
10 • reduce or eliminate sifting of the inorganic particle prior to incorporation in the
polymeric films;
• maintain or improve the dispersion of the inorganic particulate material;
• maintain or decrease the moisture pick-up of the inorganic particulate material;
• downgauging (production of thinner films);
15 • maintain or increase the breathability (e.g. MVTR) of the film;
• maintain the strength and flexibility of the film;
• lower level of “volatile” components in the film at high processing temperatures;
• improve processing of polymeric compositions (e.g. masterbatches or fibres or
polymeric films (e.g. by reduce running time));
20 • allow for faster line speeds in producing the inorganic particulate material
and/or the polymeric films;
• retention of the inorganic particulate material in the polymeric films (i.e.
reduction of “dusting”);
• improved cavitation agent for breathable films.
25
The details, examples and preferences provided in relation to any particular one or
more of the stated aspects of the present invention apply equally to all aspects of the
present invention. Any combination of the embodiments, examples and preferences
described herein in all possible variations thereof is encompassed by the present
30 invention unless otherwise indicated herein, or otherwise clearly contradicted by
context.
DETAILED DESCRIPTION OF THE INVENTION
7
Inorganic Particulate Material
An inorganic particulate material suitable for use in polymeric compositions such as
5 polymeric films is disclosed herein. In certain embodiments, the inorganic particulate
material comprises equal to or greater than about 3 ppm of particles having a particle
size equal to or greater than about 25 μm. In certain embodiments, the inorganic
particulate material comprises equal to or greater than about 3 ppm of particles having
a particle size equal to or greater than about 40 μm. In certain embodiments, the
10 inorganic particulate material has not undergone dry sieving or sifting. The inorganic
particulate material may have a d98 of less than about 11 μm or less than about 8 μm.
Inorganic particulate materials having these particle size properties have
advantageously been found to be suitable for use in polymer compositions such as
polymeric films. In particular, these inorganic particulate materials have been useful in
15 downgauging of polymeric films without causing processing issues such as increasing
of running time for the formation of the films. In particular, these inorganic particulate
materials have been useful in reducing the viscosity of polymer melts, for example at
high loading concentrations (e.g. more than 50 wt%). Surprisingly, it has been found
that these advantageous properties are maintained when the inorganic particulate
20 material includes some very coarse particles (e.g. particles equal to or greater than
about 25μm or equal to or greater than about 40 μm).
The inorganic particulate material may comprise equal to or greater than about 3 ppm
of particles having a particle size equal to or greater than about 25 μm. In certain
25 embodiments, the inorganic particulate material comprises equal to or greater than
about 5 ppm of particles having a particle size equal to or greater than about 25 μm, for
example equal to or greater than about 10 ppm, for example equal to or greater than
about 20 ppm, for example equal to or greater than about 50 ppm of particles having a
particle size equal to or greater than about 25 μm. In certain embodiments, the
30 inorganic particulate material comprises equal to or greater than about 0.01 wt% of
particles having a particle size equal to or greater than about 25 μm, for example equal
to or greater than about 0.02 wt%, for example equal to or greater than about 0.03
wt%, for example equal to or greater than about 0.04 wt%, for example equal to or
8
greater than about 0.05 wt% of particles having a particle size equal to or greater than
about 25 μm.
In certain embodiments, the inorganic particulate material comprises up to about 1.5
5 wt% of particles having a particle size equal to or greater than about 25 μm. In certain
embodiments, the inorganic particulate material comprises up to about 1 wt%, for
example up to about 0.9 wt%, for example up to about 0.8 wt%, for example up to
about 0.7 wt%, for example up to about 0.6 wt%, for example up to about 0.5 wt%, for
example up to about 0.4 wt% of particles having a particle size equal to or greater than
10 about 25 μm.
The inorganic particulate material may comprise equal to or greater than about 3 ppm
of particles having a particle size equal to or greater than about 40 μm. In certain
embodiments, the inorganic particulate material comprises equal to or greater than
15 about 5 ppm of particles having a particle size equal to or greater than about 40 μm, for
example equal to or greater than about 10 ppm, for example equal to or greater than
about 20 ppm, for example equal to or greater than about 50 ppm of particles having a
particle size equal to or greater than about 40 μm. In certain embodiments, the
inorganic particulate material comprises equal to or greater than about 0.01 wt% of
20 particles having a particle size equal to or greater than about 40 μm, for example equal
to or greater than about 0.02 wt%, for example equal to or greater than about 0.03
wt%, for example equal to or greater than about 0.04 wt%, for example equal to or
greater than about 0.05 wt% of particles having a particle size equal to or greater than
about 40 μm.
25
In certain embodiments, the inorganic particulate material comprises up to about 1.5
wt% of particles having a particle size equal to or greater than about 40 μm. In certain
embodiments, the inorganic particulate material comprises up to about 1 wt%, for
example up to about 0.9 wt%, for example up to about 0.8 wt%, for example up to
30 about 0.7 wt%, for example up to about 0.6 wt%, for example up to about 0.5 wt%, for
example up to about 0.4 wt% of particles having a particle size equal to or greater than
about 40 μm.
9
The inorganic particulate material may comprise equal to or greater than about 3 ppm
of particles having a particle size equal to or greater than about 38 μm or about 30 μm
or about 25 μm or about 20 μm. In certain embodiments, the inorganic particulate
material comprises equal to or greater than about 5 ppm of particles having a particle
5 size equal to or greater than about 38 μm or about 30 μm or about 25 μm or about 20
μm, for example equal to or greater than about 10 ppm, for example equal to or greater
than about 20 ppm, for example equal to or greater than about 50 ppm of particles
having a particle size equal to or greater than about 38 μm or about 30 μm or about 25
μm or about 20 μm. In certain embodiments, the inorganic particulate material
10 comprises equal to or greater than about 0.01 wt% of particles having a particle size
equal to or greater than about 38 μm or about 30 μm or about 25 μm or about 20 μm,
for example equal to or greater than about 0.02 wt%, for example equal to or greater
than about 0.03 wt%, for example equal to or greater than about 0.04 wt%, for example
equal to or greater than about 0.05 wt% of particles having a particle size equal to or
15 greater than about 38 μm or about 30 μm or about 25 μm or about 20 μm.
In certain embodiments, the inorganic particulate material comprises up to about 2 wt%
of particles having a particle size equal to or greater than about 38 μm or about 30 μm
or about 25 μm or about 20 μm. In certain embodiments, the inorganic particulate
20 material comprises up to about 1 wt%, for example up to about 0.9 wt%, for example
up to about 0.8 wt%, for example up to about 0.7 wt%, for example up to about 0.6
wt%, for example up to about 0.5 wt%, for example up to about 0.4 wt% of particles
having a particle size equal to or greater than about 38 μm or about 30 μm or about 25
μm or about 20 μm.
25
The inorganic particulate material may have a d98 (top-cut) of less than about 11 μm. In
certain embodiments, the inorganic particulate material has a d98 equal to or less than
about 10 μm, for example less than about 9 μm, for example less than about 8 μm, for
example less than about 7.5 μm, for example equal to or less than about 7 μm, for
30 example equal to or less than about 6.5 μm, for example equal to or less than about 6
μm, for example equal to or less than about 5.5. μm, for example equal to or less than
about 5 μm. In certain embodiments, the inorganic particulate material has a d98
ranging from about 3 μm to about 11 μm or from about 3 μm to about 10 μm or from
about 3 μm to about 9 μm or from about 3 μm to about 8 μm, for example from about
10
3.5 μm to about 7 μm, for example from about 4 μm to about 6 μm, for example from
about 4.5 μm to about 5.5 μm, for example about 5 μm.
The inorganic particulate material may, for example, have a d50 ranging from about 0.5
5 μm to about 3 μm , for example from about 0.5 μm to about 2.75 μm, for example
from about 0.5 μm to about 2.5 μm, for example from about 0.75 μm to about 2.2 μm,
for example from about 0.8 μm to about 2 μm. In certain embodiments, the inorganic
particulate material has a d50 ranging from about 0.5 μm to about 1.5 μm, for example
from about 0.6 μm to about 1.4 μm, for example from about 0.7 μm to about 1.3 μm, for
10 example from about 0.75 μm to about 1.25 μm, for example from about 0.8 μm to about
1.2 μm, for example from about 0.9 μm to about 1.1 μm, for example about 1 μm. In
certain embodiments, the inorganic particulate material has a d50 ranging from about 1
μm to about 2.5 μm, for example from about 1.5 μm to about 2.5 μm, for example from
about 1.5 μm to about 2 μm, for example from about 1.7 μm to about 2 μm.
15
The % of inorganic particulate material particles smaller than 0.75 μm may, for
example, be equal to or less than about 40 wt%, for example equal to or less than
about 39 wt%, for example equal to or less than about 38 wt%, for example equal to or
less than about 37 wt%, for example equal to or less than about 36 wt%, for example
20 equal to or less than about 35 wt%. In certain embodiments, the % of inorganic
particulate material particles smaller than 0.75 μm is equal to or less than about 25
wt%, for example equal to or less than about 24 wt%, for example equal to or less than
about 23 wt%, for example equal to or less than about 22 wt%, for example equal to or
less than about 21 wt%, for example equal to or less than about 20 wt%. In certain
25 embodiments, the % of particles smaller than 0.75 μm may be equal to or greater than
about 1 wt%, for example equal to or greater than about 2 wt%, for example equal to or
greater than about 5 wt%.
The % of inorganic particulate material particles smaller than 0.5 μm may, for example,
30 be equal to or less than about 25 wt%, for example equal to or less than about 24 wt%,
for example equal to or less than about 23 wt%, for example equal to or less than
about 22 wt%, for example equal to or less than about 21 wt%, for example equal to or
less than about 20 wt%. In certain embodiments, the % of inorganic particulate material
particles smaller than 0.5 μm is equal to or less than about 15 wt%, for example equal
11
to or less than about 14 wt%, for example equal to or less than about 13 wt%, for
example equal to or less than about 12 wt%. In certain embodiments, the % of particles
smaller than 0.5 μm may be equal to or greater than about 1 wt%, for example equal to
or greater than about 2 wt%, for example equal to or greater than about 5 wt%.
5
The % of inorganic particulate material particles smaller than 5 μm may, for example,
range from about 85 wt% to about 99 wt%, for example from about 90 wt% to about 99
wt%. In certain embodiments, the % of particles smaller than about 5 μm may range
from about 85 wt% to about 95 wt%, for example from about 90 wt% to about 95 wt%.
10 In certain embodiments, the % of particles smaller than about 5 μm may range from
about 90 wt% to about 99 wt%, for example from about 95 wt% to about 99 wt%.
The % of inorganic particulate material particles smaller than 2 μm may, for example,
range from about 40 wt% to about 95 wt%, for example from about 45 wt% to about 90
15 wt%, for example from about 50 wt% to about 90 wt%. In certain embodiments, the %
of particles smaller than 2 μm may range from about 40 wt% to about 70 wt%, for
example from about 45 wt% to about 65 wt%, for example from about 50 wt% to about
60 wt%. In certain embodiments, the % of particles smaller than 2 μm may range from
about 70 wt% to about 95 wt%, for example from about 75 wt% to about 90 wt%, for
20 example from about 80 wt% to about 90 wt%.
The % of inorganic particulate material particles smaller than 1 μm may, for example,
range from about 15 wt% to about 65 wt%, for example from about 20 wt% to about 60
wt%, for example from about 25 wt% to about 55 wt%. In certain embodiments, the %
25 of particles smaller than 1 μm may range from about 15 wt% to about 40 wt%, for
example from about 15 wt% to about 35 wt%, for example from about 20 wt% to about
35 wt%, for example from about 20 wt% to about 30 wt%. In certain embodiments, the
% of particles smaller than 1 μm may range from about 30 wt% to about 60 wt%, for
example from about 40 wt% to about 60 wt%, for example from about 45 wt% to about
30 55 wt%.
The inorganic particulate material may, for example, have a steepness factor of at least
about 35. For example, the inorganic particulate material may have a steepness factor
ranging from about 35 to about 55, for example from about 40 to about 50, for example
12
from about 41 to about 49, for example from about 42 to about 48, for example from
about 43 to about 47, for example from about 44 to about 46, for example about 45.
Steepness factor is defined as (d30/d70) x 100.
5 In certain embodiments, the inorganic particulate material has a d98 of less than about
8 μm, a d50 ranging from about 0.5 μm to about 1.5 μm, a % of particles smaller than 5
μm ranging from about 90 wt% to about 99 wt%, a % of particles smaller than 2 μm
ranging from about 75 wt% to about 95 wt% and a % of particles smaller than 1 μm
ranging from about 40 wt% to about 60 wt%.
10
In certain embodiments, the inorganic particulate material has a d98 of less than about
6 μm, a d50 ranging from about 0.75 μm to about 1.25 μm, a % of particles smaller than
5 μm ranging from about 95 wt% to about 99 wt%, a % of particles smaller than 2 μm
ranging from about 80 wt% to about 90 wt% and a % of particles smaller than 1 μm
15 ranging from about 44 wt% to about 55 wt%.
In certain embodiments, the inorganic particulate material has a d98 of less than about
5 μm, a d50 of about 1 μm, a % of particles smaller than 5 μm ranging from about 96
wt% to about 99 wt%, a % of particles smaller than 2 μm ranging from about 82 wt% to
20 about 88 wt% and a % of particles smaller than 1 μm ranging from about 47 wt% to
about 53 wt%.
In certain embodiments, the inorganic particulate material has a d98 of less than about
8 μm, a d50 ranging from about 1 μm to about 2.5 μm, a % of particles smaller than 5
25 μm ranging from about 90 wt% to about 99 wt%, a % of particles smaller than 2 μm
ranging from about 45 wt% to about 65 wt% and a % of particles smaller than 1 μm
ranging from about 20 wt% to about 35 wt%.
In certain embodiments, the inorganic particulate material has a d98 of less than about
30 7 μm, a d50 ranging from about 1.5 μm to about 2 μm, a % of particles smaller than 5
μm ranging from about 90 wt% to about 97 wt%, a % of particles smaller than 2 μm
ranging from about 50 wt% to about 60 wt% and a % of particles smaller than 1 μm
ranging from about 22 wt% to about 32 wt%.
13
In certain embodiments, the inorganic particulate material has a d98 of less than about
7 μm, a d50 ranging from about 1.7 to about 1.9 μm, a % of particles smaller than 5 μm
ranging from about 92 wt% to about 97 wt%, a % of particles smaller than 2 μm
ranging from about 52 wt% to about 58 wt% and a % of particles smaller than 1 μm
5 ranging from about 24 wt% to about 30 wt%.
The % of particles smaller than 0.25 μm may, for example, be equal to or less than
about 10 wt%, for example equal to or less than about 9 wt%, for example equal to or
less than about 8 wt%, for example equal to or less than about 7 wt%, for example
10 equal to or less than about 6 wt%, for example equal to or less than about 4 wt%. The
% of particles smaller than 0.25 μm may, for example, be at least about 1 wt%.
The % of particles smaller than 0.1 μm may, for example, be equal to or less than
about 5 wt%, for example equal to or less than about 4 wt%, for example equal to or
15 less than about 3 wt%, for example equal to or less than about 2 wt%. The % of
particles smaller than 0.1 μm may, for example, be at least about 0.1 wt%.
Unless otherwise stated, particle size properties referred to herein for the inorganic
particulate materials are as measured in a well known manner by sedimentation of the
20 particulate filler or material in a fully dispersed condition in an aqueous medium using
a Sedigraph 5100 machine as supplied by Micromeritics Instruments Corporation,
Norcross, Georgia, USA (telephone: +17706623620; web-site:
www.micromeritics.com), referred to herein as a “Micromeritics Sedigraph 5100 unit”.
Such a machine provides measurements and a plot of the cumulative percentage by
25 weight 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 weight of the
particles which have an equivalent spherical diameter less than that d50 value. The d98
and the d90 are the values determined in this way of the particle e.s.d. at which there
30 are 98% and 90% respectively by weight of the particles which have an equivalent
spherical diameter less than that d98 or d90 value. Unless otherwise stated, particle size
properties referred to herein refer to the particle size properties of the inorganic
particulate materials prior to any surface treatment (i.e. without coating).
14
The desired particle size distribution may, for example, be obtained by any suitable
method known to those skilled in the art. For example, the desired particle size
distribution may be obtained using one or more of the following methods, dry sieving or
sifting, removal of fine particles before they become “overground” (e.g. using
5 hydrocyclone), removing particles from dry products by air-classification, Ostwald
ripening process.
The inorganic particulate material may, for example, be alkali earth metal carbonate,
(for example dolomite, i.e. CaMg(CO3)2, or calcium carbonate), metal sulphate, (for
10 example barite or gypsum), metal silicate, metal oxide (for example titania, iron oxide,
chromia, antimony trioxide or silica), metal hydroxide (for example alumina trihydrate),
kaolin, calcined kaolin, wollastonite, bauxite, talc or mica, including combinations
thereof. For example, the inorganic particulate material may be an alkali earth metal
carbonate such as calcium carbonate. Hereinafter, the present invention may tend to
15 be discussed in terms of calcium carbonate. However, the invention should not be
construed as being limited to calcium carbonate.
The particulate calcium carbonate used in the present invention may be obtained from
a natural source by grinding or may be prepared synthetically by precipitation (PCC), or
20 may be a combination of the two, i.e. a mixture of the naturally derived ground material
and the synthetic precipitated material. The PCC may also be ground.
Ground calcium carbonate (GCC), i.e. ground natural calcium carbonate is typically
obtained by grinding a mineral source such as chalk, marble or limestone, which may
25 be followed by a particle size classification step, in order to obtain a product having the
desired degree of fineness. 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.
30
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
15
contents of which are incorporated by reference in their entirety) for more information
regarding the wet grinding of calcium carbonate.
When the filler is obtained from naturally occurring sources, it may be that some
5 mineral impurities will inevitably contaminate the ground material. For example,
naturally occurring calcium carbonate occurs in association with other minerals. Also,
in some circumstances, minor additions of other minerals may be included, for
example, one or more of kaolin, calcined kaolin, wollastonite, bauxite, talc or mica,
could also be present. In general, however, the filler used in the invention will contain
10 less than 5% by weight, preferably less than 1% by weight of other mineral impurities.
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
15 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, 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-
20 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 must be substantially
completely separated from the calcium carbonate if this process is to be commercially
25 attractive. 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.
30 The process for making PCC results in very pure calcium carbonate crystals and water.
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.
16
Optionally, the inorganic particulate material may be surface-treated (coated). For
example, the inorganic particulate material (e.g. calcium carbonate (GCC or PCC))
may be coated with a hydrophobising surface treatment agent such as an aliphatic
5 compound. For example, the calcium carbonate may be coated with one or more
aliphatic carboxylic acids or salts thereof having at least 10 chain carbon atoms. For
example, the calcium carbonate may be coated with one or more fatty acids or salts or
esters thereof. The fatty acids may be selected from stearic acid, palmitic acid,
behenic acid, montanic acid, capric acid, lauric acid, myristic acid, isostearic acid and
10 cerotic acid. The coated/surface-treated calcium carbonate may be a stearate coated
calcium carbonate (e.g. ammonium stearate coated calcium carbonate). The inventors
of the present invention have found that stearate coated calcium carbonate is
particularly effective, even more particularly stearate coated GCC.
15 In certain embodiments, the level of coating is such that the inorganic particulate
material is substantially in monolayer form. This may, for example, mean that there is a
slight excess of coating. This may, for example, be advantageous in that the additional
coating provides additional lubrication for the finer particles and there may, for
example, be low levels of volatiles at high temperatures during processing of polymeric
20 films. The level of coating may be about 0.5 wt% to about 1.5 wt%, for example about
0.8 wt% to about 1.3 wt% based on the dry weight of the particulate filler.
Other suitable coated or treated fillers include treated calcined kaolin and treated talc.
The calcined kaolin may, for example, be treated with a silane (e.g. an organo-silane)
25 or propylene glycol, while talc may be treated with a silane (e.g. an organo-silane).
The filler may be dried prior to inclusion in a composition. For example, the filler may
be dried before being combined with a polymer resin. Typically, the filler may be dried
in a conventional oven at about 80°C. The polymer may be dried in a vacuum oven at
30 approximately 80ºC. The particulate filler may be dried to an extent such that the
particulate filler has and maintains an adsorbed water (or moisture) content not greater
than about 0.5wt%, for example and particularly advantageously, not greater than
about 0.2 wt% or not greater than about 0.1wt% based on the dry weight of the
particulate filler. This includes both uncoated and coated particulate fillers. Low levels
17
of adsorbed water are particularly beneficial when the filler is used to form breathable
films.
Desirably, the particulate filler, including when either coated or uncoated, is not
5 susceptible to further substantial moisture pick-up. The particulate filler may, for
example, have a moisture level not greater than about 0.5 wt%, for example not greater
than about 0.2 wt%, for example not greater than about 0.1wt% after exposure to an
atmosphere of 97% or more relative humidity for 48 hours at a temperature of 20°C.
10 The particulate filler may be free or substantially free of hygroscopic or hydrophilic
compounds. For example, during grinding of the particulate filler, the grinding may be
carried out in the absence of added hygroscopic or hydrophilic compounds, or if wet
ground, any dispersant employed may be minimised and/or subsequently removed
from the filler in a known manner. For example, not greater than about 0.05 wt% of a
15 hydrophilic component may be present on the particulate filler based on the dry weight
of the particulate filler. For example, not greater than about 0.0 5wt% of a dispersant,
for example, a hydrophilic dispersant, may be present on the particulate filler based on
the dry weight of the particulate filler. An example of such a dispersant is sodium
polyacrylate. The moisture level may be measured in a known manner, e.g. by a Karl
20 Fischer (KF) titration apparatus. In this method, the water may be driven off from the
sample by heating and then measured using the quantitative reaction of water with
iodine. In coulometric KF titration, the sample is added to a pyridine-methanol solution
(with iodine and sulphur dioxide as principal components). The iodine generated
electrolytically at the anode, reacts with water. The amount of water can be directly
25 determined from the quantity of electric charge required for electrolysis.
Compositions Comprising the Inorganic Particulate Material
Compositions comprising the inorganic particulate material disclosed herein (including
30 all embodiments and combinations thereof) are also disclosed. The compositions may,
for example, be an aqueous slurry. The compositions may, for example be polymer
compositions comprising a polymer and the inorganic particulate material. The polymer
compositions may, for example, be a polymeric film, a polymer fibre, a woven or
nonwoven material, a synthetic paper (paper made partly or completely from synthetic
18
polymer, for example having the properties of traditional paper such as folder and
printing, but does not tear, puncture or absorb water as easily) or raffia (e.g. in raffia
tape or woven raffia packaging) (e.g. polypropylene raffia). In certain embodiments, the
inorganic particulate material is incorporated into a polymer film. In certain
5 embodiments, the inorganic particulate material is incorporated into a lamination
coating, for example a polyethylene lamination coating (e.g. low density polyethylene
(LDPE) lamination coating). Advantageously, the inorganic particulate material is
incorporated into a breathable polymer film.
10 The polymer film comprises a polymer and an inorganic particulate material. The
polymer may be a homopolymer or a copolymer. Suitable polymers include
thermoplastic resins such as polyolefin resin, for example, including mono-olefin
polymers of ethylene, propylene, butene or the like, functionalized derivatives and
physical blends and copolymers of the same. Typical examples of the polyolefin resin
15 include polyethylene resins such as a low-density polyethylene, linear low density
polyethylene (ethylene-a-olefin copolymer), middle-density polyethylene and highdensity
polyethylene; polypropylene resins such as polypropylene and ethylenepolypropylene
copolymer; poly (4-methylpentene); polybutene; ethylene-vinyl acetate
copolymer; polyvinyl chloride; polyethylene terephthalate; and mixtures thereof. These
20 polyolefin resins may be obtained by polymerisation in a known way, e.g. by the use of
a Ziegler catalyst, or obtained by the use of a single site catalyst such as a metallocene
catalyst. In certain embodiments, the polymer film is biaxially oriented polypropylene
(BOPP) or biaxially oriented polyethylene terephthalate (BOPET).
25 Before use, the polymer may be dried until a required level of dryness is attained. The
inorganic particulate material may also be independently dried before mixing with the
polymer.
Optionally, the polymer composition (e.g. polymer film) may further comprise one or
30 more additives. Examples of useful additives include, but are not limited to, opacifying
agents, pigments, colorants, slip agents, antioxidants, anti-fog agents, anti-static
agents, anti-block agents, moisture barrier additives, gas barrier additives, hydrocarbon
resins or hydrocarbon waxes. In certain embodiments, the polymer film further
comprises a bonding or tackifying agent.
19
Optionally, the polymer composition (e.g. polymer film) may further comprise one or
more additional inorganic particulate materials (not in accordance with the inorganic
particulate materials of the invention). Additional fillers may, for example, be calcium
5 carbonate, barium sulphate, calcium sulphate, barium carbonate, magnesium
hydroxide, aluminium hydroxide, zinc oxide, magnesium oxide, titanium oxide, silica,
talc, kaolin and combinations thereof.
The inorganic particulate material, which may or may not have been surface treated,
10 may be incorporated in polymer compositions and is typically present at a
concentration of about 1 wt% to about 80 wt%, for example from about 1 wt% to about
60 wt%, for example from about 2 to 55 wt% by weight of the final polymer film. For
example, the inorganic particulate material may be incorporated in polymer
compositions at a concentration of about 5 to 50 wt%, for example, about 10 to 25 wt%.
15 For use in breathable films, the inorganic particulate material, which may or may not
have been surface treated, may be incorporated in polymer compositions and is
typically present at a concentration of about 30 wt% to about 55 wt% by weight of the
final polymer film, for example, about 45 wt% to about 55 wt%.
20 The polymer may be incorporated in the composition is typically present at a
concentration of about 45% to about 98% by weight of the final polymer composition
(e.g. polymer film). For example, the polymer is typically present at a concentration of
about 50% to about 95%, for example about 50% to about 90%, for example about
55% to about 90%, for example about 60% to about 85%, for example about 65% to
25 about 80%, by weight of the final polymer composition (e.g. polymer film).
A film is a sheet or layer or material having an average thickness of up to 250 μm. The
polymer film may, for example, have a thickness ranging from about 5 μm to about 250
μm. For example, the polymer film may have a thickness ranging from about 5 μm to
30 about 50 μm, for example from about 5 μm to about 20 μm, for example from about 5
μm to about 15 μm, for example from about 5 μm to about 10 μm.
The polymer film may, for example, be a breathable polymer film in that it allows
transmission of gases and vapours. The polymer film may, for example, have a
20
moisture vapour transmission rate (MVTR) ranging from about 2000 gsm/day to about
15,000 gsm/day as calculated in accordance with ASTM E96/E96M-05. For example,
the polymer film may have a MVTR of at least about 3000 gsm/day, for example at
least about 4000 gsm/day, for example at least about 5000 gsm/day, for example at
5 least about 6000 gsm/day. For example, the polymer film may have a MVTR ranging
from about 5000 to about 15,000 gsm/day, for example from about 8000 to about
15,000 gsm/day, for example from about 10,000 to about 15,000 gsm/day, for example
from about 11,000 to about 14,000 gsm/day, for example from about 11,000 to about
13,000 gsm/day, for example from about 11,000 to about 12,000 gsm/day.
10
The inorganic particulate material disclosed herein may be used in a polymeric film in
order to reduce liberation of inorganic particulate material from the polymeric film
and/or to reduce deposition of the inorganic particulate material on the polymeric film
surface (dusting). The reduction may, for example, be in comparison to polymeric film
15 that is identical except that it does not comprise an inorganic particulate material in
accordance with any aspect or embodiment of the invention.
Methods of Making the Compositions
20 Methods of making the polymer compositions (e.g. polymer films) described herein are
also disclosed. The polymer (resin) may be melted (or otherwise softened) prior to
formation of the polymer composition (e.g. film), and the polymer will not normally be
subjected to any further chemical transformations. After formation of the polymer
composition (e.g. film), the polymer resin may be cooled and allowed to harden.
25
The polymer composition may be made by methods which are well known in the art
generally in which a particulate filler and a polymer are mixed together in suitable ratios
to form a blend (so-called “compounding”). The polymer may be in a liquid form to
enable the particles of the filler to be dispersed therein. Where the polymers are solid
30 at ambient temperatures, the polymer resin may need to be melted before the
compounding can be accomplished. In some embodiments, the particulate filler may
be dry blended with particles of the polymer, dispersion of the particles in the resin then
being accomplished when the melt is obtained prior to forming a film from the melt, for
example in an extruder itself.
21
In embodiments of the invention, the polymer and the particulate filler and, if
necessary, any other optional additives, may be formed into a suitable masterbatch by
the use of a suitable compounder/mixer in a manner known per se, and may be
5 pelletized, e.g. by the use of a single screw extruder or a twin-screw extruder which
forms strands which may be cut or broken into pellets. The compounder may have a
single inlet for introducing the filler and the polymer resin together. Alternatively,
separate inlets may be provided for the filler and the polymer resin. Suitable
compounders are available commercially, for example from Coperion (formerly Werner
10 & Pfleiderer).
The polymer compositions according to the present invention can be processed to
form, or to be incorporated in, polymer films in any suitable way. Methods of making
polymer films (e.g. lamination coatings) are well known to those of ordinary skill in the
15 art and may be prepared in a conventional manner. Known methods include the use of
casting, extruding and blowing processes. For example, extrusion blown film lines may
be used. For those instances where combinations of polymers are used, then coextrusion
techniques may be used. Methods of co-extrusion are well known to the
person of ordinary skill. Typically, two or more streams of molten polymer resin are
20 joined into a single extrudate stream in such a way that the resins bond together but do
not mix. Generally, a separate extruder is required for each stream and the extruders
are linked so that the extrudates can flow together in an appropriate manner for the
desired application. For making layered films, several extruders may be used in
combination and fed together into a complex die that will merge each of the resin
25 streams into a layered film or sandwich material.
The use of fillers in breathable films is described in WO 99/61521, US6569527 B1 and
WO 2013/061068, the contents of which are incorporated herein in their entirety by
reference.
30
In the manufacture of a breathable film a blend or masterbatch of the polymer (e.g.
thermoplastic polyolefin resin) and the filler may first be produced by mixing and
compounding prior to the film production stages. The mixture of ingredients to be
blended by compounding may include, in addition to the resin and the particulate filler,
22
other known optional ingredients employed in thermoplastic films, e.g. one or more of
bonding or tackifying agents, plasticisers, lubricants, anti-oxidants, ultraviolet
absorbers, dyes, colourants. A bonding or tackifying agent where employed may
facilitate bonding of the film after formation to another member, e.g. a nonwoven
5 fibrous layer, or one or more non porous layers.
The polymer, the filler and, if necessary, other optional additives, may be mixed by the
use of a suitable compounder/mixer e.g. a Henschel mixer, a super mixer, a tumbler
type mixer or the like, and kneaded and may be pelletized, e.g. by the use of a single
10 screw extruder or a twin-screw extruder which forms strands which may be cut or
broken into pellets. The masterbatch or blend, e.g. in the form of pellets, may be
melted and moulded or shaped into a film by the use of a known moulding and film
forming machine.
15 The film may be a blown film, cast film or extruded film. The film as initially formed may
be generally too thick and too noisy as it tends to make a rattling sound when shaken
and the film may not yet have a sufficient degree of breathability as measured by its
water vapour transmission rate. Consequently, the film may be heated, e.g. to a
temperature of about 5°C less than the melting point of the thermoplastic polymer or
20 more, and then stretched to at least about 1.2 times, for example at least about 2.5
times, its original length to thin the film and make it porous.
An additional feature of the thinning process is the change in opacity of the film. As
formed, the film is relatively transparent but after stretching, it becomes opaque. In
25 addition, while the film becomes orientated during the stretching process, it also
becomes softer and it does not have the degree of rattle that it does prior to stretching.
Taking all these factors into consideration, and the desire to have a water vapour
transmission rate of, for example, at least 100 grams per square metre per 24 hours,
the film may, for example, be thinned to such an extent that it has a weight per unit
30 area of less than about 35 grams per square metre for personal care absorbent article
applications and a weight per unit area of less than about 18 grams per square metre
for certain other applications.
23
The moulding and film forming machine may, for example, comprise an extruder
equipped with a T-die or the like or an inflation moulding machine equipped with a
circular die. The film production may be carried out at some time after the masterbatch
production, possibly at a different manufacturing plant. In some cases, the
5 masterbatch can directly be formed into the film without producing an intermediate
product, e.g. by pelletizing.
The film can be stretched in at least a uniaxial direction at a temperature of from room
temperature to the softening point of the resin in a known manner such as a roll
10 method or a tenter method to bring about the interfacial separation of the resin and the
particulate filler from each other, whereby a porous film can be prepared. The
stretching may be carried out by one step or by several steps. Stretch magnification
determines film breakage at high stretching as well as breathability and the moisture
vapour transmission of the obtained film, and so excessively high stretch magnification
15 and excessively low stretch magnification are desirably avoided. The stretch
magnification is preferably in the range of about 1.2 to 5 times, for example about 1.2
to 4 times in at least a uniaxial direction. If biaxial stretching is carried out, it is possible
that, for example, stretching in a first direction is applied in the machine direction or a
direction perpendicular thereto, and stretching in a second direction is then applied at
20 right angles to the first direction. Alternatively, the biaxial stretching may be carried out
simultaneously in the machine direction and the direction perpendicular thereto.
After the stretching, a heat setting treatment may be carried out if required in order to
stabilise the shape of obtained voids. The heat setting treatment may be, for example,
25 a heat setting treatment at a temperature in the range of from the softening point of the
resin to a temperature less than the melting point of the resin for a period of about 0.1
to about 100 seconds. The thickness should preferably be such as to obtain film
unlikely to tear or break and which has appropriate softness and good feel.
30 Uses of the Compositions
The porous, or breathable, film prepared in accordance with the present invention may
have a suitable breathability, moisture vapour transmission and feeling as well as
excellent mechanical properties and long-term adhesive properties. The breathable film
24
may, for example, be suitably used in products such as disposable diapers, body fluid
absorbing pads and bed sheets; medical materials such as surgical gowns and base
materials for hot compress; clothing materials such as jumpers, rainwear; building
materials such as wallpapers and waterproof materials for roofs and house wraps;
5 packaging materials for packaging desiccants, dehumidifying agents, deoxidizers,
insecticides, disposable body warmers; packaging materials for keeping the freshness
of various articles and foods; separators for the cells; and the like. The breathable film
is particularly desirable as a material used in products such as disposable diapers and
body fluid absorbing pads. The breathable film may in such products be formed into a
10 composite or laminate with one or more other layers, e.g. a nonwoven fibrous layer,
e.g. by an adhesive or bonding agent.
For the avoidance of doubt, the present invention may be as defined in any one of the
following numbered paragraphs:
15
1. An inorganic particulate material comprising:
(a) equal to or more than about 3 ppm of particles having a particle size equal
to or greater than about 40 μm and having a d98 less than about 11 μm;or
(b) equal to or more than about 3 ppm of particles having a particle size equal
20 to or greater than about 40 μm and equal to or less than about 40 wt% of
particles smaller than about 0.75 μm; or
(c) equal to or less than about 40 wt% of particles smaller than about 0.75 μm
and having a d98 less than about 11 μm.
25 2. The inorganic particulate material of paragraph 1, comprising equal to or more
than about 3 ppm of particles having a particle size equal to or greater than
about 25 μm.
3. The inorganic particulate material of paragraph 1 or 2, comprising equal to or
30 more than about 3 ppm of particles having a particle size equal to or greater
than about 38 μm or equal to or greater than about 30 μm or equal to or greater
than about 25 μm or equal to or greater than about 20 μm.
25
4. The inorganic particulate material of any one of paragraphs 1 to 3, having a d50
ranging from about 0.5 to about 3 μm, for example from about 0.5 to about 2.5
μm.
5 5. The inorganic particulate material of any one of paragraphs 1 to 4, having a d50
ranging from about 0.5 μm to about 1.5 μm, for example from about 0.75 μm to
about 1.25 μm.
6. The inorganic particulate material of any one of paragraphs 1 to 5, having a d50
10 ranging from about 1 μm to about 2.5 μm, for example from about 1.5 μm to
about 2 μm.
7. The inorganic particulate material of any one of paragraphs 1 to 6, having a d98
equal to or less than about 8 μm, for example equal to or less than about 7 μm,
15 for example equal to or less than about 6 μm, for example equal to or less than
about 5 μm.
8. The inorganic particulate material of any one of paragraphs 1 to 7, wherein the
inorganic particulate material is an alkali earth metal carbonate.
20
9. The inorganic particulate material of any one of paragraphs 1 to 8, wherein the
inorganic particulate material is calcium carbonate, for example ground calcium
carbonate (GCC).
25 10. The inorganic particulate material of any one of paragraphs 1 to 9, having a
steepness factor ranging from about 35 to about 50, for example ranging from
about 40 to about 45.
11. The inorganic particulate material of any one of paragraphs 1 to 10, wherein the
30 inorganic particulate material is surface-treated with a hydrophobising agent.
12. The inorganic particulate material of any one of paragraphs 1 to 11, wherein the
inorganic particulate material is surface-treated with an aliphatic compound.
26
13. The inorganic particulate material of any one of paragraphs 1 to 12, wherein the
inorganic particulate material is surface-treated with a fatty acid or salt thereof,
for example stearic acid or a salt thereof.
5 14. The inorganic particulate material of any one of paragraphs 8 to 13, wherein the
coating is substantially in monolayer form.
15. The inorganic particulate material of any one of paragraphs 1 to 14, having a
moisture pick-up after 48 hours equal to or less than about 0.2 wt% at 97%
10 relative humidity, for example equal to or less than about 0.1 wt% at 97%
relative humidity.
16. The inorganic particulate material of any one of paragraphs 1 to 15, wherein the
% of particles smaller than 0.75 μm is equal to or less than about 40 wt%, for
15 example equal to or less than about 37 wt%.
17. The inorganic particulate material of any one of paragraphs 1 to 16, wherein the
% of particles smaller than 0.5 μm is equal to or less than about 25 wt%, for
example equal to or less than about 20 wt%, for example equal to or less than
20 about 15 wt%.
18. An inorganic particulate material having a d98 less than about 11 μm or equal to
or less than about 8 μm, wherein the inorganic particulate material has not
undergone dry sieving or sifting.
25
19. The inorganic particulate material of paragraph 18, comprising equal to or
greater than about 3 ppm of particles having a particle size greater than or
equal to about 25 μm.
30 20. The inorganic particulate material of paragraph 18 or 19, comprising equal to or
more than about 3 ppm of particles having a particle size equal to or greater
than about 40 μm.
21. The inorganic particulate material of any one of paragraphs 18 to 20,
35 comprising equal to or more than about 3 ppm of particles having a particle size
27
equal to or greater than about 38 μm or equal to or greater than about 30 μm or
equal to or greater than about 25 μm or equal to or greater than about 20 μm.
22. The inorganic particulate material of any one of paragraphs 18 to 21, having a
5 d50 ranging from about 0.5 to about 3 μm, for example from about 0.5 to about
2.5 μm.
23. The inorganic particulate material of any one of paragraphs 18 to 22, having a
d50 ranging from about 0.5 μm to about 1.5 μm, for example from about 0.75 μm
10 to about 1.25 μm.
24. The inorganic particulate material of any one of paragraphs 18 to 23, having a
d50 ranging from about 1 μm to about 2.5 μm, for example from about 1.5 μm to
about 2 μm.
15
25. The inorganic particulate material of any one of paragraphs 18 to 24, having a
d98 equal to or less than about 8μm, for example equal to or less than about 7
μm, for example equal to or less than about 6 μm, for example equal to or less
than about 5 μm.
20
26. The inorganic particulate material of any one of paragraphs 18 to 25, wherein
the inorganic particulate material is an alkali earth metal carbonate.
27. The inorganic particulate material of any one of paragraphs 18 to 26, wherein
25 the inorganic particulate material is calcium carbonate, for example ground
calcium carbonate (GCC).
28. The inorganic particulate material of any one of paragraphs 18 to 27, having a
steepness factor ranging from about 35 to about 50, for example ranging from
30 about 40 to about 45.
29. The inorganic particulate material of any one of paragraphs 18 to 28, wherein
the inorganic particulate material is surface-treated with a hydrophobising
agent.
35
28
30. The inorganic particulate material of any one of paragraphs 19 to 29, wherein
the inorganic particulate material is surface-treated with an aliphatic compound.
31. The inorganic particulate material of any one of paragraphs 18 to 30, wherein
5 the inorganic particulate material is surface-treated with a fatty acid or salt
thereof, for example stearic acid or a salt thereof.
32. The inorganic particulate material of any one of paragraphs 18 to 31, wherein
the coating is substantially in monolayer form.
10
33. The inorganic particulate material of any one of paragraphs 18 to 32, having a
moisture pick-up after 48 hours equal to or less than about 0.2 wt% at 97%
relative humidity, for example equal to or less than about 0.1 wt% at 97%
relative humidity.
15
34. The inorganic particulate material of any one of paragraphs 18 to 33, wherein
the % of particles smaller than 0.75 μm is equal to or less than about 40 wt%,
for example equal to or less than about 37 wt%.
20 35. An inorganic particulate material having a d98 of less than 11 μm and
comprising equal to or more than about 3 ppm of particles having a particle size
equal to or greater than about 25 μm.
36. The inorganic particulate material of paragraph 35, comprising equal to or more
25 than about 3 ppm of particles having a particle size equal to or greater than
about 40 μm.
37. The inorganic particulate material of paragraph 35 or 36, comprising equal to or
more than about 3 ppm of particles having a particle size equal to or greater
30 than about 38 μm or equal to or greater than about 30 μm or equal to or greater
than about 25 μm or equal to or greater than about 20 μm.
38. The inorganic particulate material of any one of paragraphs 35 to 37, having a
d50 ranging from about 0.5 to about 3 μm, for example from about 0.5 to about
35 2.5 μm.
29
39. The inorganic particulate material of any one of paragraphs 35 to 38, having a
d50 ranging from about 0.5 μm to about 1.5 μm, for example from about 0.75 μm
to about 1.25 μm.
5 40. The inorganic particulate material of any one of paragraphs 35 to 38, having a
d50 ranging from about 1 μm to about 2.5 μm, for example from about 1.5 μm to
about 2 μm.
The inorganic particulate material of any one of paragraphs 35 to 40, having a
d98 equal to or less than about 8 μm, for example equal to or less than about 7
μm, for example equal to or less than about 6 μm, for example equal to or less
than about 5 μm.
42. The inorganic particulate material of any one of paragraphs 35 to 41, wherein
15 the inorganic particulate material is an alkali earth metal carbonate.
43. The inorganic particulate material of any one of paragraphs 35 to 42, wherein
the inorganic particulate material is calcium carbonate, for example ground
calcium carbonate (GCC).
20
44. The inorganic particulate material of any one of paragraphs 35 to 43, having a
steepness factor ranging from about 35 to about 50, for example ranging from
about 40 to about 45.
25 45. The inorganic particulate material of any one of paragraphs 35 to 44, wherein
the inorganic particulate material is surface-treated with a hydrophobising
agent.
46. The inorganic particulate material of any one of paragraphs 35 to 45, wherein
30 the inorganic particulate material is surface-treated with an aliphatic compound.
47. The inorganic particulate material of any one of paragraphs 35 to 46, wherein
the inorganic particulate material is surface-treated with a fatty acid or salt
thereof, for example stearic acid or a salt thereof.
35
48. The inorganic particulate material of any one of paragraphs 35 to 47, wherein
the coating is substantially in monolayer form.
30
41.
10
49. The inorganic particulate material of any one of paragraphs 35 to 48, having a
moisture pick-up after 48 hours equal to or less than about 0.2 wt% at 97%
relative humidity, for example equal to or less than about 0.1 wt% at 97%
5 relative humidity.
50. The inorganic particulate material of any one of paragraphs 35 to 49, wherein
the % of particles smaller than 0.75 μm is equal to or less than about 40 wt%,
for example equal to or less than about 37 wt%.
10
51. A composition comprising the inorganic particulate material of any one of
paragraphs 1 to 50.
52. The composition of paragraph 51, further comprising a polymer, for example
15 selected from polypropylene (PP), polyethylene (PE) (e.g. low density
polyethylene), polyvinyl chloride (PVC), polyethylene terephthalate (PET) and
any combination thereof.
The composition of paragraph 52, wherein the composition is a polymer film,
(for example a lamination coating and/or for example a blown film, cast film or
extruded film) or a synthetic paper or raffia (for example raffia tape or raffia
packaging).
The composition of aim any one of paragraphs 51 or 53, wherein the
composition comprises at least about 1 wt% of the inorganic particulate material
of any one of paragraph 1 to 50, for example at least about 20 wt% of the
inorganic particulate material of any one of paragraphs 1 to 50.
55. The composition of any one of paragraphs 51 to 54, wherein the composition
30 comprises at least about 40 wt% polymer, for example at least about 50 wt%
polymer.
56. The composition of any one of paragraphs 53 to 55, wherein the film has a
thickness equal to or less than about 100 μm, for example equal to or less than
35 about 50 μm, for example equal to or less than about 20 μm.
53.
20
54.
25
31
57. The composition of any one of paragraphs 53 to 56, wherein the film has a
thickness ranging from 5 μm to 100 μm, for example from about 5 μm to about
20 μm.
5 58. The composition of any one of paragraphs 53 to 57, wherein the film is
breathable, for example wherein the film has a moisture vapour transmission
rate (MVTR) equal to or greater than about 2000 gsm per day, for example from
about 2000 to about 15,000 gsm per day.
10 59. Use of the inorganic particulate material of any one of paragraphs 1 to 50 in a
polymer composition (e.g. in polymeric film such as lamination coating,
synthetic paper, raffia).
The use of paragraph 59, wherein the polymeric is selected from polypropylene
(PP), polyethylene (PE) (e.g. low density polyethylene), polyvinyl chloride
(PVC), polyethylene terephthalate (PET) and any combination thereof, for
example wherein the polymeric film is biaxially oriented polypropylene (BOPP)
or biaxially oriented polyethylene terephthalate (BOPET).
20 61. The use of paragraph 59 or 60, wherein the polymer composition is a polymeric
film and the polymeric film is breathable.
62. A method of making a polymeric film, the method comprising:
mixing (e.g. compounding) an inorganic particulate material of any one
25 of paragraphs 1 to 50 with a polymer; and
shaping the compounded material into a film.
63. The method of paragraph 62, wherein the polymer is selected from
polypropylene (PP), polyethylene (PE) (e.g. low density polyethylene), polyvinyl
30 chloride (PVC), polyethylene terephthalate (PET) and any combination thereof.
64. The method of paragraph 62 or 63, wherein the polymeric film stretched to form
a breathable film.
60.
15
32
65. Use of the inorganic particulate material of any one of paragraphs 1 to 50 as a
cavitation agent.
66. Use of the inorganic particulate material of any one of paragraphs 1 to 50 in a
5 polymeric film in order to reduce liberation of inorganic particulate material from
the polymeric film and/or to reduce deposition of inorganic particulate material
on the surface of the polymeric film.
EXAMPLES
10
Example 1
A ground calcium carbonate (GCC1) particulate material was prepared and the particle
size distribution was measured by Sedigraph. The results are shown in Table 1.
15
Table 1.
Property
>25 μm (ppm)
< 10 μm (wt%)
< 5 μm (wt%)
< 2 μm (wt%)
< 1 μm (wt%)
< 0.75 μm (wt%)
< 0.5 μm (wt%)
d50 (μm)
d98 (μm)
Steepness Factor
GCC1
3.00
99.60
98.90
84.60
50.00
35.50
20.50
1.00
< 5
45
The GCC was surface-treated with stearic acid. Differential Scanning Calorimetry
20 (DSC) indicated a slight excess above monolayer coating. Without wishing to be bound
by theory, it is though that this gives additional lubrication to the fine particles.
33
The surface-treated GCC1 was tested for moisture pick-up over 48 hours at a
temperature of 20 C and relative humidity of 97%. It was found that the surface-treated
GCC1 had a moisture pick-up of less than 0.2 wt%.
5 The surface-treated GCC1 may be incorporated into a polymer without encountering
processing problems such as reduced running time, despite the presence of some very
coarse (larger than 25 μm) particles.
Example 2
10
A ground calcium carbonate (GCC2) particulate material was prepared and the particle
size distribution was measured by Sedigraph. The results are shown in Table 2.
15
Table 2.
Property
>25 μm (ppm)
< 10 μm (wt%)
< 5 μm (wt%)
< 2 μm (wt%)
< 1 μm (wt%)
< 0.75 μm (wt%)
< 0.5 μm (wt%)
d50 (μm)
d98 (μm)
Steepness Factor
GCC2
5
99.30
94.9
55.2
27.0
18.9
11.6
1.8
6.2
40.1
20 The GCC2 was surface-treated with stearic acid. Differential Scanning Calorimetry
(DSC) indicated a slight excess above monolayer coating. Without wishing to be bound
by theory, it is though that this gives additional lubrication to the fine particles.
34
The surface-treated GCC2 was tested for moisture pick-up over 48 hours at a
temperature of 20 C and relative humidity of 97%. It was found that the surface-treated
GCC1 had a moisture pick-up of less than 0.1 wt%.
5 The surface-treated GCC2 may be incorporated into a polymer film without
encountering processing problems such as reduced running time, despite the presence
of some very coarse (larger than 25 μm) particles.
Example 3
10
The surface-coated GCC used in Example 1 above (GCC1) and another ground
calcium carbonate surface treated with stearic acid and having an approximate particle
size distribution as shown in Table 3.(GCC3) were incorporated into linear low-density
polyethylene produced by a blown film line at a thickness of 30 μm. These films were
15 then stretched on a lab machine direction orientation line between 3 and 5 times to
simulate the industrial process. The films had a loading level of ground calcium
carbonate between 50 and 55 wt%.
Table 3.
Property
>25 μm (ppm)
< 5 μm (wt%)
< 2 μm (wt%)
< 1 μm (wt%)
< 0.75 μm (wt%)
< 0.5 μm (wt%)
d50 (μm)
d98 (μm)
GCC3
9.00
96.0
58.0
28.0
20.0
12.0
1.7
7.8
20 A black cloth was held against the film surfaces during stretching of the film to remove
any dust. The black cloths were then viewed under a microscope at a magnification of
x25. It was surprisingly found that no particles were visible on the black cloth used with
the film incorporating GCC1, whereas some particles are visible on the black cloth
used with the film incorporating GCC3.
25
35
WE CLAIM:
1. An inorganic particulate material comprising:
(a) equal to or more than about 3 ppm of particles having a particle size
5 equal to or greater than about 40 μm and having a d98 less than about
11 μm;or
(b) equal to or more than about 3 ppm of particles having a particle size
equal to or greater than about 40 μm and equal to or less than about 40
wt% of particles smaller than about 0.75 μm; or
10 (c) equal to or less than about 40 wt% of particles smaller than about 0.75
μm and having a d98 less than about 11 μm; or
(d) an inorganic particulate material that has not undergone dry sieving or
sifting and having a d98 less than about 11 μm or equal to or less than
about 8 μm; or
15 (e) equal to or more than about 3 ppm of particles having a particle size
equal to or greater than about 25 μm and having a d98 of less than 11
μm.
2. The inorganic particulate material of claim 1, comprising equal to or more than
20 about 3 ppm of particles having a particle size equal to or greater than about 38
μm or equal to or greater than about 30 μm or equal to or greater than about 25
μm or equal to or greater than about 20 μm.
3. The inorganic particulate material of claim 1 or 2, having a d50 ranging from
25 about 0.5 to about 3 μm, for example from about 0.5 to about 2.5 μm.
4. The inorganic particulate material of any one of claims 1 to 3, having a d98 equal
to or less than about 8 μm, for example equal to or less than about 7 μm, for
example equal to or less than about 6 μm, for example equal to or less than
30 about 5 μm.
5. The inorganic particulate material of any one of claims 1 to 4, wherein the
inorganic particulate material is an alkali earth metal carbonate such as calcium
carbonate, for example ground calcium carbonate (GCC).
35
36
6. The inorganic particulate material of any one of claims 1 to 5, having a
steepness factor ranging from about 35 to about 50, for example ranging from
about 40 to about 45.
5 7. The inorganic particulate material of any one of claims 1 to 6, wherein the
inorganic particulate material is surface-treated with a hydrophobising agent.
8. The inorganic particulate material of any one of claims 1 to 7, having a moisture
pick-up after 48 hours equal to or less than about 0.2 wt% at 97% relative
10 humidity, for example equal to or less than about 0.1 wt% at 97% relative
humidity.
9. The inorganic particulate material of any one of claims 1 to 8, wherein the % of
particles smaller than 0.75 μm is equal to or less than about 40 wt%, for
15 example equal to or less than about 37 wt%, and/or wherein the % of particles
smaller than 0.5 μm is equal to or less than about 25 wt%, for example equal to
or less than about 20 wt%, for example equal to or less than about 15 wt%.
10. A composition comprising the inorganic particulate material of any one of claims
20 1 to 9, for example wherein the composition further comprises a polymer, for
example selected from polypropylene (PP), polyethylene (PE) (e.g. low density
polyethylene), polyvinyl chloride (PVC), polyethylene terephthalate (PET) and
any combination thereof.
25 11. The composition of claim 10, wherein the composition is a polymer film, (for
example a lamination coating and/or for example a blown film, cast film or
extruded film) or a synthetic paper or raffia (for example raffia tape or raffia
packaging).
30 12. The composition of claim 10 or 11, wherein the composition is a film, for
example having a thickness equal to or less than about 100 μm, for example
equal to or less than about 50 μm, for example equal to or less than about 20
μm.
35 13. The composition of any one of claims 10 to 12, wherein the film is breathable,
for example wherein the film has a moisture vapour transmission rate (MVTR)
37
equal to or greater than about 2000 gsm per day, for example from about 2000
to about 15,000 gsm per day.
14. Use of the inorganic particulate material of any one of claims 1 to 9 in a polymer
5 composition (e.g. in polymeric film such as lamination coating or a breathable
film, synthetic paper, raffia), or as a cavitation agent.
15. A method of making a polymeric film, the method comprising:
mixing (e.g. compounding) an inorganic particulate material of any one
10 of claims 1 to 9 with a polymer; and
shaping the compounded material into a film.