Note: Descriptions are shown in the official language in which they were submitted.
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MICROPOROUS MATERIAL
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part application of U.S.
Patent
Application No. 13/473,001 filed May 16, 2012, now abandoned, which is a
continuation
of U.S. Patent Application No. 12/761,020, filed April 15, 2010, now U.S.
Patent
8,435,631, both of which are incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The present invention relates to microporous materials that possess
controlled
volatile material transfer properties. The microporous material includes
thermoplastic
organic polymer, particulate filler, and a network of interconnecting pores.
BACKGROUND OF THE INVENTION
[0003] The delivery of volatile materials, such as fragrances, e.g., air
fresheners, may
be achieved by means of a delivery apparatus that includes a reservoir
containing volatile
material. The delivery apparatus or delivery device typically includes a vapor
permeable
membrane that covers or encloses the reservoir. Volatile material within the
reservoir
passes through the vapor permeable membrane and is released into the
atmosphere, e.g.,
air, on the atmospheric side of the membrane. Vapor permeable membranes are
typically
fabricated from organic polymers and are porous.
[0004] The rate at which volatile material passes through the vapor
permeable
membrane is generally an important factor. For example, if the rate at which
volatile
material passes through the vapor permeable membrane is too low, properties
associated
with the volatile material, such as fragrance, will typically be undesirably
low or
imperceptible. If, on the other hand, the rate at which volatile material
passes through the
vapor permeable membrane is too high, the reservoir of volatile material may
be depleted
too quickly, and properties associated with the volatile material, such as
fragrance, may
be undesirably high or in some instances overpowering.
[0005] It is also generally desirable to minimize or prevent the formation
of liquid
volatile material on the atmospheric or exterior side of the vapor permeable
membrane,
from which the volatile material is released into the atmosphere, e.g., into
the air. Liquid
volatile material that passes through the exterior side of the vapor permeable
membrane
may collect, e.g., puddle, within or on the exterior side of the membrane and
leak from
the delivery device resulting in, for example, staining of articles, such as
clothing or
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furniture, that come into contact with the liquid volatile material. In
addition, the
formation of liquid volatile material on the exterior side of the vapor
permeable
membrane may result in the uneven release of volatile material from the
delivery device.
[0006] Further increases in ambient temperature may increase the rate at
which
volatile material passes through the vapor permeable membrane to undesirably
high rates.
For example, a delivery device that is used within the passenger compartment
of an
automobile may be exposed to increases in ambient temperature. As such,
minimizing
the increase in the rate at which volatile material contained within the
device passes
through the vapor permeable membrane, as a function of increasing ambient
temperature,
is typically desirable.
[0007] It would be desirable to develop new microporous materials that
possess
controlled volatile material transfer properties. It would be further
desirable that when
such newly developed microporous materials are used as a vapor permeable
membrane in
a delivery device, the microporous material minimizes the formation of liquid
volatile
material on the exterior side or surface of the membrane. In addition, the
rate at which
volatile material passes through such microporous materials should increase
minimally
with increases in ambient temperature.
SUMMARY OF THE INVENTION
[0008] In accordance with the present invention there is provided, a
microporous
material comprising:
(a) a matrix of substantially water-insoluble thermoplastic organic polymer
comprising polyolefin;
(b) finely divided, substantially water-insoluble particulate filler, said
particulate
filler being distributed throughout said matrix and constituting from 40 to 90
percent by
weight, based on the total weight of said microporous material; and
(c) a network of interconnecting pores communicating substantially
throughout
said microporous material;
wherein said microporous material has
a density of at least 0.8 g/cm3,
a volatile material contact surface,
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a vapor release surface, wherein said volatile material contact surface and
said
vapor release surface are substantially opposed to each other, and
a volatile material transfer rate from said volatile material contact surface
to
said vapor release surface of from 0.04 to 0.6 mg / (hour* cm2), and
wherein when volatile material is transferred from said volatile material
contact surface to said vapor release surface (at a volatile material transfer
rate of from
0.04 to 0.6 mg/ (hour* cm2)), said vapor release surface is substantially free
of volatile
material in liquid form.
[0009] Further, the present invention provides a microporous material
comprising:
(a) a matrix of substantially water-insoluble thermoplastic organic polymer
comprising polyolefin;
(b) finely divided, substantially water-insoluble particulate filler, said
particulate
filler being distributed throughout said matrix and constituting from 40 to 90
percent by
weight, based on the total weight of said microporous material; and
(c) a network of interconnecting pores communicating substantially
throughout
said microporous material;
wherein said microporous material has
a density of less than 0.8 g/cm3,
a volatile material contact surface,
a vapor release surface, wherein said volatile material contact surface and
said
vapor release surface are substantially opposed to each other, wherein (i) at
least a
portion of said volatile material contact surface has a first coating thereon,
and/or (ii) at
least a portion of said vapor release surface has a second coating thereon,
a volatile material transfer rate from said volatile material contact surface
to
said vapor release surface of from 0.04 to 0.6 mg / (hour* cm2), and
wherein when volatile material is transferred from said volatile material
contact surface to said vapor release surface (at a volatile material transfer
rate of from
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0.04 to 0.6 mg/ (hour* cm2)), said vapor release surface is substantially free
of volatile
material in liquid form.
[0010] Also, the present invention provides, a microporous material
comprising:
(a) a matrix of substantially water-insoluble thermoplastic organic polymer
comprising polyolefin;
(b) finely divided, substantially water-insoluble particulate filler, said
particulate
filler being distributed throughout said matrix and constituting from 40 to 90
percent by
weight, based on the total weight of said microporous material; and
(c) a network of interconnecting pores communicating substantially
throughout
said microporous material;
wherein said microporous material has,
a volatile material contact surface,
a vapor release surface, wherein said volatile material contact surface and
said
vapor release surface are substantially opposed to each other, wherein (i) at
least a portion
of said volatile material contact surface has a first coating thereon, and/or
(ii) at least a
portion of said vapor release surface has a second coating thereon, wherein
said first
coating and said second coating are each independently selected from a coating
composition comprising poly(vinyl alcohol), and
a volatile material transfer rate, from said volatile material contact surface
to
said vapor release surface, of at least 0.04 mg/(hour* cm2), and
wherein when said microporous material, i.e., the poly(vinyl alcohol coated
microporous material, is exposed to a temperature increase of from 25 C to 60
C, said
volatile material transfer rate increases by less than or equal to 150
percent.
DETAILED DESCRIPTION OF THE INVENTION
[0011] As used herein and in the claims, the term "volatile material
contact surface"
means that surface of the microporous material that faces and, typically, is
in contact with
the volatile material, which is, for example, contained in a reservoir, as
described in
further detail below.
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[0012] As used herein and in the claims, the term "vapor release surface"
means that
surface of the microporous material that does not face and/or contact directly
the volatile
material, and from which surface volatile material is released into an
exterior atmosphere
in a gaseous or vapor form.
[0013] As used herein and in the claims, the term "(meth)acrylate" and
similar terms,
such as "esters of (meth)acrylic acid", means acrylates and/or methacrylates.
[0014] As used herein and in the claims, the "volatile material transfer
rate" of the
microporous materials was determined in accordance with the following
description. A
test reservoir, having an interior volume sufficient to contain 2 milliliters
of volatile
material, such as benzyl acetate, was fabricated from a clear thermoplastic
polymer. The
interior dimensions of the reservoir was defined by a circular diameter at the
edge of the
open face of approximately 4 centimeters and a depth of no greater than 1
centimeter.
The open face was used to determine the volatile material transfer rate. With
the test
reservoir laying flat (with the open face facing upward), about 2 milliliters
of benzyl
acetate was introduced into the test reservoir. With benzyl acetate introduced
into the test
reservoir, a sheet of microporous material having a thickness of from 6 to 18
mils was
placed over the open face/side of the test reservoir, such that 12.5 cm2 of
the volatile
material contact surface of the microporous sheet was exposed to the interior
of the
reservoir. The test reservoir was weighed to obtain an initial weight of the
entire charged
assembly. The test reservoir, containing benzyl acetate and enclosed with the
sheet of
microporous material, was then placed, standing upright, in a laboratory
chemical fume
hood having approximate dimensions of 5 feet [1.52 meters] (height) x 5 feet
[1.52
meters] (width) x 2 feet [0.61 meters] (depth). With the test reservoir
standing upright,
benzyl acetate was in direct contact with at least a portion of the volatile
material contact
surface of the microporous sheet. The glass doors of the fume hood were pulled
down,
and the air flow through the hood was adjusted so as to have eight (8) turns
(or turnovers)
of hood volume per hour. Unless otherwise indicated, the temperature in the
hood was
maintained at 25 C 5 C. The humidity within in the fume hood was ambient.
The test
reservoirs were regularly weighed in the hood. The calculated weight loss of
benzyl
acetate, in combination with the elapsed time and surface area of the
microporous sheet
exposed to the interior of the test reservoir, were used to determine the
volatile transfer
rate of the microporous sheet, in units of mg / (hour* cm2).
[0015] As used herein and in the claims, the percent increase in the
volatile material
transfer rate of the microporous material of the present invention from 25 C
to 60 C was
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determined for separate but substantially equivalent microporous material
sheet samples
at 25 C and 60 C, in accordance with the method described above. Reservoirs
were
placed in a large glass bell jar and over a 50% aqueous solution of potassium
chloride
also contained in the bell jar. The entire bell jar with contents was placed
in an oven
heated to 60 C. The reservoirs were held under these conditions for a period
of 7 to 10
hours. The reservoirs were then returned to the hood at ambient conditions
overnight and
the process was repeated over several days. Each of the reservoirs was weighed
before
being placed in the bell jar and after being removed from the bell jar. Upon
removal
from the bell jar, the weight of each reservoir was taken after the reservoir
had returned to
ambient temperature.
[0016] As used herein and in the claims, the following method was used to
determine
if the vapor release surface of the microporous material is "substantially
free of volatile
material in liquid form". When the test reservoirs were weighed, as described
above, the
vapor release surface of the microporous sheet was examined visually by naked
eye to
determine if drops and/or a film of liquid were present thereon. If any
evidence of drops
(i.e., a single drop) and/or a film of liquid was visually observed on the
vapor release
surface, but did not run off the surface, the microporous sheet was considered
to be
acceptable. If the drops of volatile material liquid ran off the vapor release
surface, the
microporous sheet was determined to have failed. If no evidence of drops
(i.e., not one
drop) and/or a film of liquid was visually observed on the vapor release
surface, the
microporous sheet was determined to be substantially free of volatile material
in liquid
form.
[0017] Unless otherwise indicated, all ranges disclosed herein are to be
understood to
encompass any and all sub-ranges subsumed therein. For example, a stated range
of "1 to
10" should be considered to include any and all sub-ranges between (and
inclusive of) the
minimum value of 1 and the maximum value of 10; that is, all subranges
beginning with a
minimum value of 1 or more and ending with a maximum value of 10 or less,
e.g., 1 to
6.1, 3.5 to 7.8, 5.5 to 10, etc. Any numerical value, however, inherently
contains certain
errors necessarily resulting from the standard deviation found in its
respective testing
measurement, including that found in the measuring instrument.
[0018] Unless otherwise indicated, all numbers or expressions, such as
those
expressing structural dimensions, quantities of ingredients, etc., as used in
the
specification and claims, are understood as modified in all instances by the
term "about."
Accordingly, unless indicated to the contrary, the numerical parameters set
forth in this
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specification and attached claims are approximations that can vary depending
upon the
desired results sought to be obtained by the present invention. At the very
least, and not
as an attempt to limit the application of the doctrine of equivalents to the
scope of the
claims, each numerical parameter should at least be construed in light of the
number of
reported significant digits and by applying ordinary rounding techniques.
Further, as used
in this specification and the attached claims, the singular forms "a", "an"
and "the" are
intended to include plural referents, unless expressly and unequivocally
limited to one
referent.
[0019] The term "volatile material", as used herein and in the claims,
means a
material that is capable of conversion to a gaseous or vapor form, i.e.,
capable of
vaporizing, at ambient room temperature and pressure, and in the absence of
imparted
additional or supplementary energy, e.g., in the form of heat and/or
agitation. The
volatile material can comprise an organic volatile material, which can include
those
volatile materials comprising a solvent-based material, or those which are
dispersed in a
solvent-based material. The volatile material may be in a liquid form and/or
in a solid
form, and may be naturally occurring or synthetically formed. When in a solid
form, the
volatile material typically sublimes from the solid form to the vapor form
without passing
thru an intermediate liquid form. The volatile material may optionally be
combined or
formulated with nonvolatile materials, such as a carrier, e.g., water and/or
nonvolatile
solvents. In the case of a solid volatile material, the nonvolatile carrier
may be in the
form of a porous material, e.g., a porous inorganic material, in which the
solid volatile
material is held. Also, the solid volatile material may be in the form of a
semi-solid gel.
[0020] The volatile material may be a fragrance material, such as a
naturally
occurring or synthetic perfume oil. Examples of perfume oils from which the
liquid
volatile material may be selected include, but are not limited to, oil of
bergamot, bitter
orange, lemon, mandarin, caraway, cedar leaf, clove leaf, cedar wood,
geranium,
lavender, orange, origanum, petitgrain, white cedar, patchouli, neroili, rose
absolute, and
combinations thereof. Examples of solid fragrance materials from which the
volatile
material may be selected include, but are not limited to, vanillin, ethyl
vanillin, coumarin,
tonalid, calone, heliotropene, musk xylol, cedrol, musk ketone benzophenone,
raspberry
ketone, methyl naphthyl ketone beta, phenyl ethyl salicylate, veltol, maltol,
maple
lactone, proeugenol acetate, evemyl, and combinations thereof.
[0021] The volatile material transfer rate of the microporous material can
be less than
or equal to 0.7 mg/ (hour* cm2), or less than or equal to 0.6 mg/(hour* cm2),
or less than
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or equal to 0.55 mg/(hour* cm2), or less than or equal to 0.50 mg/(hour* cm2).
The
volatile material transfer rate of the microporous material can be equal to or
greater than
0.02 mg/(hour* cm2), or equal to or greater than 0.04 mg/(hour* cm2), or equal
to or
greater than 0.30 mg/(hour* cm2), or equal to or greater than 0.35 mg/(hour*
cm2). The
volatile material transfer rate of the microporous material may range between
any
combination of these upper and lower values. For example, the volatile
material transfer
rate of the microporous material can be from 0.04 to 0.6 mg/(hour* cm2), or
from 0.2 to
0.6 mg/(hour* cm2), or from 0.30 to 0.55 mg/(hour* cm2), or from 0.35 to 0.50
mg/(hour*
cm2), in each case inclusive of the recited values.
[0022] While not intending to be bound by any theory, when volatile
material is
transferred from the volatile material contact surface to the vapor release
surface of the
microporous material, it is believed that the volatile material is in a form
selected from
liquid, vapor and a combination thereof In addition, and without intending to
be bound
by any theory, it is believed that the volatile material, at least in part,
moves through the
network of interconnecting pores that communicate substantially throughout the
microporous material. Typically, the transfer of volatile material occurs at
temperatures
of from 15 C to 40 C, e.g., from 15 or 18 C to 30 or 35 C. and at ambient
atmospheric
pressure.
[0023] The microporous material can have a density of at least 0.7 g/cm3,
or at least
0.8 g/cm3. As used herein and in the claims, the density of the microporous
material is
determined by measuring the weight and volume of a sample of the microporous
material.
The upper limit of the density of the microporous material may range widely,
provided it
has a targeted volatile material transfer rate of, for example, from 0.04 to
0.6 mg / (hour*
cm2), and the vapor release surface is substantially free of volatile material
in liquid form
when volatile material is transferred from the volatile material contact
surface to said
vapor release surface. Typically, the density of the microporous material is
less than or
equal to 1.5 g/cm3, or less than or equal to 1.0 g/cm3. The density of the
microporous
material can range between any of the above-stated values, inclusive of the
recited values.
For example, the microporous material can have a density of from 0.7 g/cm3 to
1.5 g/cm3,
such as, from 0.8 g/cm3 to 1.2 g/cm3, inclusive of the recited values.
[0024] When the microporous material has a density of at least 0.7 g/cm3,
such as at
least 0.8 g/cm3, the volatile material contact surface and the vapor release
surface of the
microporous material each may be free of a coating material thereon. When free
of a
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coating material thereon, the volatile material contact surface and the vapor
release
surface each are defined by the microporous material.
[0025] When the microporous material has a density of at least 0.7 g/cm3,
such as at
least 0.8 g/cm3, at least a portion of the volatile material contact surface
of the
microporous material optionally may have a first coating thereon, and/or at
least a portion
of the vapor release surface of the microporous material optionally may have a
second
coating thereon. The first coating and the second coating may be the same or
different.
When at least a portion of the volatile material contact surface has a first
coating thereon,
the volatile material contact surface is defined at least in part by the first
coating. When
at least a portion of the vapor release surface has a second coating thereon,
the vapor
release surface is defined at least in part by the second coating.
[0026] The first coating and the second coating may each be formed from a
coating
selected from liquid coatings and solid particulate coatings (e.g., powder
coatings).
Typically, the first and second coatings each independently are formed from a
coating
selected from liquid coatings, which may optionally include a solvent selected
from
water, organic solvents and combinations thereof. The first and second
coatings each
independently may be selected from crosslinkable coatings, e.g., thermosetting
coatings
and photo-curable coatings, and non-crosslinkable coatings, e.g., air-dry
coatings. The
first and second coatings may be applied to the respective surfaces of the
microporous
material in accordance with art-recognized methods, such as spray application,
curtain
coating, dip coating, and/or drawn-down coating, e.g., by means of a doctor
blade or
draw-down bar, techniques.
[0027] The first and second coating compositions each independently can
optionally
include art-recognized additives, such as antioxidants, ultraviolet light
stabilizers, flow
control agents, dispersion stabilizers, e.g., in the case of aqueous
dispersions, and
colorants, e.g., dyes and/or pigments.
Typically, the first and second coating
compositions are free of colorants, and as such are substantially clear or
opaque.
Optional additives may be present in the coating compositions in individual
amounts of
from, for example, 0.01 to 10 percent by weight, based on the total weight of
the coating
composition.
[0028] The first coating and said second coating each independently can be
formed
from an aqueous coating composition that includes dispersed organic polymeric
material.
The aqueous coating composition may have a particle size of from 200 to 400
nm. The
solids of the aqueous coating composition may vary widely, for example from
0.1 to 30
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percent by weight, or from 1 to 20 percent by weight, in each case based on
total weight
of the aqueous coating composition. The organic polymers comprising the
aqueous
coating compositions may have number average molecular weights (Mn) of, for
example,
from 1000 to 4,000,000, or from 10,000 to 2,000,000.
[0029] The aqueous coating composition can be selected from aqueous
poly(meth)acrylate dispersions, aqueous polyurethane dispersions, aqueous
silicone (or
silicon) oil dispersions, and combinations thereof. The poly(meth)acrylate
polymers of
the aqueous poly(meth)acrylate dispersions may be prepared in accordance with
art-
recognized methods. For example, the poly(meth)acrylate polymers may include
residues
(or monomer units) of alkyl (meth)acrylates having from 1 to 20 carbon atoms
in the
alkyl group. Examples of alkyl (meth)acrylates having from 1 to 20 carbon
atoms in the
alkyl group include, but are not limited to, methyl (meth)acrylate, ethyl
(meth)acrylate, 2-
hydroxyethyl (meth)acrylate, propyl (meth)acrylate, 2-hydroxypropyl
(meth)acrylate,
isopropyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, tert-
butyl
(meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, isobomyl
(meth)acrylate, cyclohexyl (meth)acrylate, and 3,3,5-trimethylcyclohexyl
(meth)acrylate.
For purposes of non-limiting illustration, an example of an aqueous
poly(meth)acrylate
dispersion from which the first and second coating compositions may each be
independently selected is HYCAR 26138, which is commercially available from
Lubrizol
Advanced Materials, Inc.
[0030] The polyurethane polymers of the aqueous polyurethane dispersions,
from
which the first and second coatings each independently may be selected,
include any of
those known to the skilled artisan. Typically the polyurethane polymers are
prepared
from isocyanate functional materials having two or more isocyanate groups, and
active
hydrogen functional materials having two or more active hydrogen groups. The
active
hydrogen groups may be selected from, for example, hydroxyl groups, thiol
groups,
primary amines, secondary amines, and combinations thereof. For purposes of
non-
limiting illustration, an example of an aqueous polyurethane dispersion from
which the
first and second coating compositions may each be independently selected is
WITCOBOND W-240, which is commercially available from Chemtura Corporation.
[0031] The silicon polymers of the aqueous silicone oil dispersions may be
selected
from known and art-recognized aqueous silicone oil dispersions. For purposes
of non-
limiting illustration, an example of an aqueous silicon dispersion from which
the first and
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second coating compositions may each be independently selected is MOMENTIVE LE-
410, which is commercially available from Momentive Performance Materials.
[0032] The first coating and the second coating each independently can be
applied at
any suitable thickness, provided the microporous material has a targeted
volatile material
transfer rate of, for example, from 0.04 to 0.6 mg / (hour* cm2), and the
vapor release
surface is substantially free of volatile material in liquid form when
volatile material is
transferred from the volatile material contact surface to said vapor release
surface. Also,
the first coating and the second coating each independently can have a coating
weight,
i.e., the weight of the coating which is on the microporous material, of from
0.01 to 5.5
g/m2, such as from 0.1 to 5.0 g/m2, or from 0.5 to 3 g/m2, or from 0.75 to 2.5
g/m2, or
from 1 to 2 g/m2.
[0033] The microporous material can have a density of less than 0.8 g/cm3,
and at
least a portion of the volatile material contact surface of the microporous
material can
have a first coating thereon, and/or at least a portion of the vapor release
surface of the
microporous material can have a second coating thereon. The first coating and
the second
coating may be the same or different, and are each independently as described
previously
herein with regard to the optional first and second coatings of the
microporous material
having a density of at least 0.8 g/cm3.
[0034] When less than 0.8 g/cm3, the density of the microporous material of
the
present invention may have any suitable lower limit, provided the microporous
material
has a targeted volatile material transfer rate of, for example, from 0.04 to
0.6 mg / (hour*
cm2), and the vapor release surface is substantially free of volatile material
in liquid form
when volatile material is transferred from the volatile material contact
surface to said
vapor release surface. With this particular embodiment of the present
invention, the
density of the microporous material may be from 0.6 to less than 0.8 g/cm3, or
from 0.6 to
0.75 g/cm3,e.g., from 0.60 to 0.75 g/cm3, or from 0.6 to 0.7 g/cm3, e.g., from
0.60 to 0.70
g/cm3õ or from 0.65 to 0.70 g/cm3.
[0035] Further, at least a portion of the volatile material contact surface
of the
microporous material can have a first coating thereon, and/or at least a
portion of the
vapor release surface of the microporous material can have a second coating
thereon, in
which the first and second coatings each independently are selected from a
coating
composition comprising a poly(vinyl alcohol).
[0036] With the poly(vinyl alcohol) coated embodiment of the present
invention,
when the microporous material, i.e., the poly(vinyl alcohol) coated
microporous material,
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is exposed to a temperature increase of from 25 C to 60 C, the volatile
material transfer
rate thereof increases by less than or equal 150 percent. When the poly(vinyl
alcohol)
coated microporous material is exposed to a temperature increase, e.g., from
an ambient
temperature of from 25 C to 60 C, the volatile material transfer rate
typically increases,
and typically does not decrease unless, for example, the microporous material
has been
damaged by exposure to the higher ambient temperature. As such, and as used
herein and
in the claims, the statement "the volatile material transfer rate thereof
increases by less
than or equal to [a stated] percent", e.g., 150 percent, is inclusive of a
lower limit of 0
percent, but is not inclusive of a lower limit that is less than 0 percent.
[0037] For purposes of illustration, when the poly(vinyl alcohol) coated
microporous
material has a volatile material transfer rate of 0.3 mg/(hour* cm2) at 25 C,
and when the
microporous material is exposed to a temperature of 60 C, the volatile
material transfer
rate increases to a value that is less than or equal to 0.75 mg/(hour* cm2).
[0038] In an embodiment when the microporous material, i.e., the poly(vinyl
alcohol)
coated microporous material, is exposed to a temperature increase of from 25 C
to 60 C,
the volatile material transfer rate thereof increases by less than or equal to
125 percent.
For example, when the poly(vinyl alcohol) coated microporous material has a
volatile
material transfer rate of 0.3 mg/(hour* cm2) at 25 C, and when the microporous
material
is exposed to a temperature of 60 C, the volatile material transfer rate
increases to a value
that is less than or equal to 0.68 mg/(hour* cm2).
[0039] Further, when the microporous material, i.e., the poly(vinyl
alcohol) coated
microporous material, is exposed to a temperature increase of from 25 C to 60
C, the
volatile material transfer rate thereof increases by less than or equal 100
percent. For
example, when the poly(vinyl alcohol) coated microporous material has a
volatile
material transfer rate of 0.3 mg/(hour* cm2) at 25 C, and when the microporous
material
is exposed to a temperature of 60 C, the volatile material transfer rate
increases to a value
that is less than or equal to 0.6 mg/(hour* cm2).
[0040] The first and second poly(vinyl alcohol) coatings may each be
independently
present in any suitable coating weight, provided the microporous material has
a targeted
volatile material transfer rate of, for example, at least 0.04 mg / (hour*
cm2), and when
the microporous material, i.e., the poly(vinyl alcohol) coated microporous
material, is
exposed to a temperature increase of from 25 C to 60 C, the volatile material
transfer rate
thereof increases by less than or equal to 150 percent. Typically, the first
poly(vinyl
alcohol) coating and the second poly(vinyl alcohol) coating each independently
have a
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coating weight of from 0.01 to 5.5 g/m2, or from 0.1 to 4.0 g/m2, or from 0.5
to 3.0 g/m2,
or from 0.75 to 2.0 g/m2.
[0041] The volatile material transfer rate of the poly(vinyl alcohol)
coated
microporous material can be at least 0.02 mg/(hour* cm2). The volatile
material transfer
rate of the poly(vinyl alcohol) coated microporous material may be equal to or
greater
than 0.04 mg/(hour*cm2), or equal to or greater than 0.1 mg/(hour* cm2), or
equal to or
greater than 0.2 mg/(hour* cm2), or equal to or greater than 0.30 mg/(hour*
cm2), or equal
to or greater than 0.35 mg/(hour* cm2). The volatile material transfer rate of
the
poly(vinyl alcohol) coated microporous material may be less than or equal to
0.7
mg/(hour* cm2), or less than or equal to 0.6 mg/(hour* cm2), or less than or
equal to 0.55
mg/(hour* cm2), or less than or equal to 0.50 mg/(hour* cm2). The volatile
material
transfer rate of the poly(vinyl alcohol) coated microporous material may range
between
any combination of these upper and lower values, inclusive of the recited
values. For
example, the volatile material transfer rate of the poly(vinyl alcohol) coated
microporous
material can be at least 0.02 mg/(hour*cm2), such as from 0.04 to 0.70
mg/(hour* cm2), or
from 0.04 to 0.60 mg/(hour* cm2), or from 0.20 to 0.60 mg/(hour* cm2), or from
0.30 to
0.55 mg/(hour* cm2), or from 0.35 to 0.50 mg/(hour* cm2), in each case
inclusive of the
recited values.
[0042] The density of the microporous material of the poly(vinyl alcohol)
coated
microporous material embodiment of the present invention may vary widely,
provided
that the poly(vinyl alcohol) coated microporous material has a targeted
volatile material
transfer rate, for example, of at least 0.04 mg / (hour* cm2), and when the
microporous
material, i.e., the poly(vinyl alcohol) coated microporous material, is
exposed to a
temperature increase of from 25 C to 60 C, the volatile material transfer rate
thereof
increases by less than or equal to 150 percent.
[0043] Further, the density of the microporous material, of the poly(vinyl
alcohol)
coated microporous material, may be at least 0.7 g/cm3, such as at least 0.8
g/cm3, e.g.,
from 0.8 to 1.2 g/cm3, all inclusive of the recited values. In an embodiment
of the present
invention, the density of the poly(vinyl alcohol) coated microporous material,
i.e., the
density of the microporous material prior to application of the poly(vinyl
alcohol)
coating, is less than 0.8 g/cm3. For example, the density of the microporous
material, of
the poly(vinyl alcohol) coated microporous material, may be from 0.6 to less
than 0.8
g/cm3, or from 0.6 to 0.75 g/cm3, e.g., from 0.60 to 0.75 g/cm3, or from 0.6
to 0.7 g/cm3,
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e.g., from 0.60 to 0.70 g/cm3õ or from 0.65 to 0.70 g/cm3, all inclusive of
the recited
values.
[0044] With regard to the poly(vinyl alcohol) coated microporous material
of the
present invention, when volatile material is transferred from the volatile
material contact
surface to the vapor release surface, the vapor release surface is
substantially free of
volatile material in liquid form.
[0045] The poly(vinyl alcohol) coating may be selected from liquid coatings
which
may optionally include a solvent selected from water, organic solvents and
combinations
thereof. The poly(vinyl alcohol) coating may be selected from crosslinkable
coatings,
e.g., thermosetting coatings, and non-crosslinkable coatings, e.g., air-dry
coatings. The
poly(vinyl alcohol) coating may be applied to the respective surfaces of the
microporous
material in accordance with art-recognized methods, such as spray application,
curtain
coating, or drawn-down coating, e.g., by means of a doctor blade or draw-down
bar.
[0046] In an embodiment, the first and second poly(vinyl alcohol) coatings
are each
independently formed from aqueous poly(vinyl alcohol) coating compositions.
The
solids of the aqueous poly(vinyl alcohol) coating composition may vary widely,
for
example from 0.1 to 15 percent by weight, or from 0.5 to 9 percent by weight,
in each
case based on total weight of the aqueous coating composition. The poly(vinyl
alcohol)
polymer of the poly(vinyl alcohol) coating compositions may have number
average
molecular weights (Mn) of, for example, from 100 to 1,000,000, or from 1000 to
750,000.
[0047] The poly(vinyl alcohol) polymer of the poly(vinyl alcohol) coating
composition may be a homopolymer or copolymer. Comonomers from which the
poly(vinyl alcohol) copolymer may be prepared include those which are
copolymerizable
(by means of radical polymerization) with vinyl acetate, and which are known
to the
skilled artisan. For purposes of illustration, comonomers from which the
poly(vinyl
alcohol) copolymer may be prepared include, but are not limited to:
(meth)acrylic acid,
maleic acid, fumaric acid, crotonic acid, metal salts thereof, alkyl esters
thereof, e.g., C2'
C10 alkyl esters thereof, polyethylene glycol esters thereof, and
polypropylene glycol
esters thereof; vinyl chloride; tetrafluoroethylene; 2-acrylamido-2-methyl-
propane
sulfonic acid and its salts; acrylamide; N-alkyl acrylamide; N,N-dialkyl
substituted
acrylamides; and N-vinyl formamide.
[0048] For purposes of non-limiting illustration, an example of a
poly(vinyl alcohol)
coating composition that may be used to form the poly(vinyl alcohol) coated
microporous
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material of the present invention is CELVOL 325 , which is commercially
available from
Sekisui Specialty Chemicals.
[0049] The first
and second poly(vinyl alcohol) coating compositions may each
independently include art-recognized additives, such as antioxidants,
ultraviolet light
stabilizers, flow control agents, dispersion stabilizers, e.g., in the case of
aqueous
dispersions, and colorants, e.g., dyes and/or pigments. Typically, the first
and second
poly(vinyl alcohol) coating compositions are free of colorants, and are as
such
substantially clear or opaque. Optional additives may be present in the
poly(vinyl
alcohol) coating compositions in individual amounts of from, for example, 0.01
to 10
percent by weight, based on the total weight of the coating composition.
[0050] The
matrix of the microporous material is composed of substantially water-
insoluble thermoplastic organic polymer. The numbers and kinds of such
polymers
suitable for use as the matrix are large. In general, any substantially water-
insoluble
thermoplastic organic polymer which can be extruded, calendered, pressed, or
rolled into
film, sheet, strip, or web may be used. The polymer may be a single polymer or
it may be
a mixture of polymers. The polymers may be homopolymers, copolymers, random
copolymers, block copolymers, graft copolymers, atactic polymers, isotactic
polymers,
syndiotactic polymers, linear polymers, or branched polymers. When mixtures of
polymers are used, the mixture may be homogeneous or it may comprise two or
more
polymeric phases.
[0051] Examples
of classes of suitable substantially water-insoluble thermoplastic
organic polymers include thermoplastic polyolefins, poly(halo-substituted
olefins),
polyesters, polyamides, polyurethanes, polyureas, poly(vinyl halides),
poly(vinylidene
halides), polystyrenes, poly(vinyl esters), polycarbonates, polyethers,
polysulfides,
polyimides, polysilanes, polysiloxanes, polycaprolactones, polyacrylates, and
polymethacrylates. Contemplated hybrid classes, from which the substantially
water-
insoluble thermoplastic organic polymers may be selected include, for example,
thermoplastic poly(urethane-ureas), poly(ester-amides), poly(silane-
siloxanes), and
poly(ether-esters. Further
examples of suitable substantially water-insoluble
thermoplastic organic polymers include thermoplastic high density
polyethylene, low
density polyethylene, ultrahigh molecular weight polyethylene, polypropylene
(atactic,
isotactic, or syndiotactic), poly(vinyl chloride), polytetrafluoroethylene,
copolymers of
ethylene and acrylic acid, copolymers of ethylene and methacrylic acid,
poly(vinylidene
chloride), copolymers of vinylidene chloride and vinyl acetate, copolymers of
vinylidene
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chloride and vinyl chloride, copolymers of ethylene and propylene, copolymers
of
ethylene and butene, poly(vinyl acetate), polystyrene, poly(omega-
aminoundecanoic acid)
poly(hexamethylene adipamide), poly(epsilon-caprolactam), and po ly
(methyl
methacrylate). The recitation of these classes and example of substantially
water-
insoluble thermoplastic organic polymers is not exhaustive, and are provided
only for
purposes of illustration.
[0052]
Substantially water-insoluble thermoplastic organic polymers may in
particular include, for example, poly(vinyl chloride), copolymers of vinyl
chloride, or
mixtures thereof. In an embodiment, the water-insoluble thermoplastic organic
polymer
includes an ultrahigh molecular weight polyolefin selected from: ultrahigh
molecular
weight polyolefin, e.g., essentially linear ultrahigh molecular weight
polyolefin) having
an intrinsic viscosity of at least 10 deciliters/gram; or ultrahigh molecular
weight
polypropylene, e.g., essentially linear ultrahigh molecular weight
polypropylene) having
an intrinsic viscosity of at least 6 deciliters/gram; or mixtures thereof. In
a particular
embodiment, the water-insoluble thermoplastic organic polymer includes
ultrahigh
molecular weight polyethylene, e.g., linear ultrahigh molecular weight
polyethylene,
having an intrinsic viscosity of at least 18 deciliters/gram.
[0053] Ultrahigh
molecular weight polyethylene (UHMWPE) is not a thermoset
polymer having an infinite molecular weight, but is technically classified as
a
thermoplastic. However, because the molecules are substantially very long
chains,
UHMWPE softens when heated but does not flow as a molten liquid in a normal
thermoplastic manner. The very long chains and the peculiar properties they
provide to
UHMWPE are believed to contribute in large measure to the desirable properties
of
microporous materials made using this polymer.
[0054] As
indicated earlier, the intrinsic viscosity of the UHMWPE is at least about
deciliters/gram. Usually the intrinsic viscosity is at least about 14
deciliters/gram.
Often the intrinsic viscosity is at least about 18 deciliters/gram. In many
cases the
intrinsic viscosity is at least about 19 deciliters/gram. Although there is no
particular
restriction on the upper limit of the intrinsic viscosity, the intrinsic
viscosity is frequently
in the range of from about 10 to about 39 deciliters/gram, e.g., in the range
of from about
14 to about 39 deciliters/gram. In most cases the intrinsic viscosity of the
UHMWPE is
in the range of from about 18 to about 39 deciliters/gram, typically from
about 18 to
about 32 deciliters/gram.
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[0055] The nominal molecular weight of UHMWPE is empirically related to
the
intrinsic viscosity of the polymer according to the equation:
M(UHMWPE) = 5.3x104[Tl] 137
where M(UHMWPE) is the nominal molecular weight and [I] is the intrinsic
viscosity of
the UHMW polyethylene expressed in deciliters/gram.
[0056] As used herein and in the claims, intrinsic viscosity is determined
by
extrapolating to zero concentration the reduced viscosities or the inherent
viscosities of
several dilute solutions of the UHMWPE where the solvent is freshly distilled
decahydronaphthalene to which 0.2 percent by weight, 3,5-di-tert-buty1-4-
hydroxyhydrocinnamic acid, neopentanetetrayl ester [CAS Registry No. 6683-19-
8] has
been added. The reduced viscosities or the inherent viscosities of the UHMWPE
are
ascertained from relative viscosities obtained at 135 degree C. using an
Ubbelohde No. 1
viscometer in accordance with the general procedures of ASTM D 4020-81, except
that
several dilute solutions of differing concentration are employed. ASTM D 4020-
81 is, in
its entirety, incorporated herein by reference.
[0057] In one particular embodiment, the matrix comprises a mixture of
substantially
linear ultrahigh molecular weight polyethylene having an intrinsic viscosity
of at least 10
deciliters/gram, and lower molecular weight polyethylene (LMWPE) having an
ASTM D
1238-86 Condition E melt index of less than 50 grams/10 minutes and an ASTM D
1238-
86 Condition F melt index of at least 0.1 gram/10 minutes. The nominal
molecular
weight of LMWPE is lower than that of the UHMW polyethylene. LMWPE is
thermoplastic and many different types are known. One method of classification
is by
density, expressed in grams/cubic centimeter and rounded to the nearest
thousandth, in
accordance with ASTM D 1248-84 (re-approved 1989), as summarized as follows:
Type Abbreviation Density (g/cm3)
Low Density Polyethylene LDPE 0.910-0.925
Medium Density Polyethylene MDPE 0.926-0.940
High Density Polyethylene HDPE 0.941-0.965
Any or all of these polyethylenes may be used as the LMWPE in the present
invention.
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For some applications, HDPE, may be used because it ordinarily tends to be
more linear
than MDPE or LDPE. ASTM D 1248-84 (Reapproved 1989) is, in its entirety,
incorporated herein by reference.
[0058] Processes for making the various LMWPE's are well known and well
documented. They include the high pressure process, the Phillips Petroleum
Company
process, the Standard Oil Company (Indiana) process, and the Ziegler process.
[0059] The ASTM D 1238-86 Condition E (that is, 190degree C. and 2.16
kilogram
load) melt index of the LMWPE is less than about 50 grams/10 minutes. Often
the
Condition E melt index is less than about 25 grams/10 minutes. Typically, the
Condition
E melt index is less than about 15 grams/10 minutes.
[0060] The ASTM D 1238-86 Condition F (that is, 190degree C. and 21.6
kilogram
load) melt index of the LMWPE is at least 0.1 gram/10 minutes. In many cases
the
Condition F melt index is at least about 0.5 gram/10 minutes. Typically, the
Condition F
melt index is at least about 1.0 gram/10 minutes. ASTM D 1238-86 is, in its
entirety,
incorporated herein by reference.
[0061] Sufficient UHMWPE and LMWPE should be present in the matrix to
provide
their properties to the microporous material. Other thermoplastic organic
polymers may
also be present in the matrix so long as their presence does not materially
affect the
properties of the microporous material in an adverse manner. One or more other
thermoplastic polymers may be present in the matrix. The amount of the other
thermoplastic polymer which may be present depends upon the nature of such
polymer.
Examples of thermoplastic organic polymers which may optionally be present
include,
but are not limited to, poly(tetrafluoroethylene), polypropylene, copolymers
of ethylene
and propylene, copolymers of ethylene and acrylic acid, and copolymers of
ethylene and
methacrylic acid. If desired, all or a portion of the carboxyl groups of
carboxyl-
containing copolymers may be neutralized with sodium, zinc, or the like.
[0062] In most cases the UHMWPE and the LMWPE together constitute at least
about 65 percent by weight of the polymer of the matrix. Often the UHMWPE and
the
LMWPE together constitute at least about 85 percent by weight of the polymer
of the
matrix. Typically, the other thermoplastic organic polymers are substantially
absent so
that the UHMWPE and the LMWPE together constitute substantially 100 percent by
weight of the polymer of the matrix.
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[0063] The UHMWPE can constitute at least one percent by weight of the
polymer of
the matrix. Where the UHMWPE and the LMWPE together constitute 100 percent by
weight of the polymer of the matrix of the microporous material, the UHMWPE
can
constitute greater than or equal to 40 percent by weight of the polymer of the
matrix, such
as greater than or equal to 45 percent by weight, or greater than or equal to
48 percent by
weight, or greater than or equal to 50 percent by weight, or greater than or
equal to 55
percent by weight of the polymer of the matrix. Also, the UHMWPE can
constitute less
than or equal to 99 percent by weight of the polymer of the matrix, such as
less than or
equal to 80 percent by weight, or less than or equal to 70 percent by weight,
or less than
or equal to 65 percent by weight, or less than or equal to 60 percent by
weight of the
polymer of the matrix. The level of UHMWPE comprising the polymer of the
matrix can
range between any of these values inclusive of the recited values.
[0064] Likewise, where the URIVIWPE and the LMWPE together constitute 100
percent by weight of the polymer of the matrix of the microporous material,
the LMWPE
can constitute greater than or equal to 1 percent by weight of the polymer of
the matrix,
such as greater than or equal to 5 percent by weight, or greater than or equal
to 10 percent
by weight, or greater than or equal to 15 percent by weight, or greater than
or equal to 20
percent by weight, or greater than or equal to 25 percent by weight, or
greater than or
equal to 30 percent by weight, or greater than or equal to 35 percent by
weight, or greater
than or equal to 40 percent by weight, or greater than or equal to 45 percent
by weight, or
greater than or equal to 50 percent by weight, or greater than or equal to 55
percent by
weight of the polymer of the matrix. Also, the LMWPE can constitute less than
or equal
to 70 percent by weight of the polymer of the matrix, such as less than or
equal to 65
percent by weight, or less than or equal to 60 percent by weight, or less than
or equal to
55 percent by weight, or less than or equal to 50 percent by weight, or less
than or equal
to 45 percent by weight of the polymer of the matrix. The level of the LMWPE
can range
between any of these values inclusive of the recited values.
[0065] It should be noted that for any of the previously described
microporous
materials of the present invention, the LMWPE can comprise high density
polyethylene.
[0066] The microporous material also includes a finely-divided,
substantially water-
insoluble particulate filler material. The particulate filler material may
include an organic
particulate material and/or an inorganic particulate material. The particulate
filler
material typically is not colored, for example, the particulate filler
material is a white or
off-white particulate filler material, such as a siliceous or clay particulate
material.
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[0067] The finely divided substantially water-insoluble filler particles
may constitute
from 20 to 90 percent by weight of the microporous material. For example, such
filler
particles may constitute from 30 percent to 90 percent by weight of the
microporous
material, or from 40 to 90 percent by weight of the microporous material, or
from 40 to
85, e.g., 45 to 80, percent by weight of the microporous material, or from 50
to 80, e.g.,
50 to 65, 70 or 75, percent by weight of the microporous material and even
from 60
percent to 90 percent by weight of the microporous material.
[0068] The finely divided substantially water-insoluble particulate filler
may be in the
form of ultimate particles, aggregates of ultimate particles, or a combination
of both. At
least about 90 percent by weight of the filler used in preparing the
microporous material
has gross particle sizes in the range of from 0.5 to about 200 micrometers,
such as from 1
to 100 micrometers, as determined by the use of a laser diffraction particle
size
instrument, LS230 from Beckman Coulton, which is capable of measuring particle
diameters as small as 0.04 micrometers. Typically, at least 90 percent by
weight of the
particulate filler has gross particle sizes in the range of from 5 to 40,
e.g., 10 to 30
micrometers. The sizes of the filler agglomerates may be reduced during
processing of
the ingredients used to prepare the microporous material. Accordingly, the
distribution of
gross particle sizes in the microporous material may be smaller than in the
raw filler
itself.
[0069] Non-limiting examples of suitable organic and inorganic particulate
materials,
that may be used in the microporous material of the present invention, include
those
described in U.S. 6,387,519 B1 at column 9, line 4 to column 13, line 62, the
cited
portions of which are incorporated herein by reference.
[0070] In a particular embodiment of the present invention, the particulate
filler
material comprises siliceous materials. Non-limiting examples of siliceous
fillers that
may be used to prepare the microporous material include silica, mica,
montmorillonite,
kaolinite, nanoclays such as cloisite, which is available from Southern Clay
Products,
talc, diatomaceous earth, vermiculite, natural and synthetic zeolites, calcium
silicate,
aluminum silicate, sodium aluminum silicate, aluminum polysilicate, alumina
silica gels
and glass particles. In addition to the siliceous fillers, other fmely divided
particulate
substantially water-insoluble fillers optionally may also be employed. Non-
limiting
examples of such optional particulate fillers include carbon black, charcoal,
graphite,
titanium oxide, iron oxide, copper oxide, zinc oxide, antimony oxide,
zirconia, magnesia,
alumina, molybdenum disulfide, zinc sulfide, barium sulfate, strontium
sulfate, calcium
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carbonate, and magnesium carbonate. Some of such optional fillers are color-
producing
fillers and, depending on the amount used, may add a hue or color to the
microporous
material. In a non-limiting embodiment, the siliceous filler may include
silica and any of
the aforementioned clays. Non-limiting examples of silicas include
precipitated silica,
silica gel, fumed silica, and combinations thereof.
[0071] Silica gel is generally produced commercially by acidifying an
aqueous
solution of a soluble metal silicate, e.g., sodium silicate, at low pH with
acid. The acid
employed is generally a strong mineral acid such as sulfuric acid or
hydrochloric acid,
although carbon dioxide can be used. Inasmuch as there is essentially no
difference in
density between the gel phase and the surrounding liquid phase while the
viscosity is low,
the gel phase does not settle out, that is to say, it does not precipitate.
Consequently,
silica gel may he described as a non-precipitated, coherent, rigid, three-
dimensional
network of contiguous particles of colloidal amorphous silica. The state of
subdivision
ranges from large, solid masses to submicroscopic particles, and the degree of
hydration
from almost anhydrous silica to soft gelatinous masses containing on the order
of 100
parts of water per part of silica by weight.
[0072] Precipitated silica generally is produced commercially by combining
an
aqueous solution of a soluble metal silicate, ordinarily alkali metal silicate
such as sodium
silicate, and an acid so that colloidal particles of silica will grow in a
weakly alkaline
solution and be coagulated by the alkali metal ions of the resulting soluble
alkali metal
salt. Various acids may be used, including but not limited to mineral acids.
Non-limiting
examples of acids that may be used include hydrochloric acid and sulfuric
acid, but
carbon dioxide can also be used to produce precipitated silica. In the absence
of a
coagulant, silica is not precipitated from solution at any pH. In a non-
limiting
embodiment, the coagulant used to effect precipitation of silica may be the
soluble alkali
metal salt produced during formation of the colloidal silica particles, or it
may be an
added electrolyte, such as a soluble inorganic or organic salt, or it may be a
combination
of both.
[0073] Many different precipitated silicas can be employed as the
siliceous filler used
to prepare the microporous material. Precipitated silicas are well-known
commercial
materials, and processes for producing them are described in detail in many
United States
Patents, including U.S. Patents 2,940,830 and 4,681,750. The average ultimate
particle
size (irrespective of whether or not the ultimate particles are agglomerated)
of
precipitated silica used to prepare the microporous material is generally less
than 0.1
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micrometer, e.g., less than 0.05 micrometer or less than 0.03 micrometer, as
determined
by transmission electron microscopy. Precipitated silicas are available in
many grades
and forms from PPG Industries, Inc. These silicas are sold under the Hi-Sil
trademark.
[0074] For purposes of the present invention, the finely divided
particulate
substantially water-insoluble siliceous filler can comprise at least 50
percent by weight,
e.g., at least 65 or at least 75 percent by weight, or at least 90 percent by
weight of the
substantially water-insoluble filler material. The siliceous filler may
comprise from 50 to
90 percent by weight, e.g., from 60 to 80 percent by weight, of the
particulate filler
material, or the siliceous filler may comprise substantially all of the
substantially water-
insoluble particulate filler material.
[0075] The particulate filler, e.g., the siliceous filler, typically has a
high surface area,
which allows the filler to carry much of the processing plasticizer
composition used to
produce the microporous material of the present invention. High surface area
fillers are
materials of very small particle size, materials that have a high degree of
porosity, or
materials that exhibit both of such properties. The surface area of the
particulate filler,
e.g., the siliceous filler particles, can range from 20 or 40 to 400 square
meters per gram,
e.g., from 25 to 350 square meters per gram, or from 40 to 160 square meters
per gram, as
determined by the Brunauer, Emmett, Teller (BET) method according to ASTM D
1993-
91. The BET surface area is determined by fitting five relative pressure
points from a
nitrogen sorption isotherm measurement made using a Micromeritics TriStar
3000TM
instrument. A FlowPrep-O6OTM station can be used to provide heat and
continuous gas
flow during sample preparation. Prior to nitrogen sorption, silica samples are
dried by
heating to 160 V in flowing nitrogen (PS) for 1 hour. Generally, but not
necessarily, the
surface area of any non-siliceous filler particles used is also within one of
these ranges..
The filler particles are substantially water-insoluble and also can be
substantially
insoluble in any organic processing liquid used to prepare the microporous
material. This
can facilitate retention of the particulate filler within the microporous
material.
[0076] The microporous material of the present may also include minor
amounts, e.g.,
less than or equal to 5 percent by weight, based on total weight of the
microporous
material, of other materials used in processing, such as lubricant, processing
plasticizer,
organic extraction liquid, water, and the like. Further materials introduced
for particular
purposes, such as thermal, ultraviolet and dimensional stability, may
optionally be present
in the microporous material in small amounts, e.g., less than or equal to 15
percent by
weight, based on total weight of the microporous material. Examples of such
further
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materials include, but are not limited to, antioxidants, ultraviolet light
absorbers,
reinforcing fibers such as chopped glass fiber strand, and the like. The
balance of the
microporous material, exclusive of filler and any coating, printing ink, or
impregnant
applied for one or more special purposes is essentially the thermoplastic
organic polymer.
[0077] The microporous material of the present invention, also includes a
network of
interconnecting pores, which communicate substantially throughout the
microporous
material. On a coating-free, printing ink free and impregnant-free basis,
pores typically
constitute from 35 to 95 percent by volume, based on the total volume of the
microporous
material, when made by the processes as further described herein. The pores
may
constitute from 60 to 75 percent by volume of the microporous material, based
on the
total volume of the microporous material. As used herein and in the claims,
the porosity
(also known as void volume) of the microporous material, expressed as percent
by
volume, is determined according to the following equation:
Porosity = 100[1-di /d2]
where, di is the density of the sample, which is determined from the sample
weight and
the sample volume as ascertained from measurements of the sample dimensions;
and d2 is
the density of the solid portion of the sample, which is determined from the
sample
weight and the volume of the solid portion of the sample. The volume of the
solid portion
of the microporous material is determined using a Quantachrome
stereopycnometer
(Quantachrome Corp.) in accordance with the operating manual accompanying the
instrument.
[0078] The volume average diameter of the pores of the microporous
material is
determined by mercury porosimetry using an Autoscan mercury porosimeter
(Quantachrome Corp.) in accordance with the operating manual accompanying the
instrument. The volume average pore radius for a single scan is automatically
determined
by the porosimeter. In operating the porosimeter, a scan is made in the high
pressure
range (from 138 kilopascals absolute to 227 megapascals absolute). If 2
percent or less
of the total intruded volume occurs at the low end (from 138 to 250
kilopascals absolute)
of the high pressure range, the volume average pore diameter is taken as twice
the volume
average pore radius determined by the porosimeter. Otherwise, an additional
scan is
made in the low pressure range (from 7 to 165 kilopascals absolute) and the
volume
average pore diameter is calculated according to the equation:
d = 2 [ viri/wi + v2r2/w2] / [vi/ wi + v2/ w2]
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where, d is the volume average pore diameter; vi is the total volume of
mercury intruded
in the high pressure range; v2 is the total volume of mercury intruded in the
low pressure
range; ri is the volume average pore radius determined from the high pressure
scan; r2 is
the volume average pore radius determined from the low pressure scan; wi is
the weight
of the sample subjected to the high pressure scan; and w2 is the weight of the
sample
subjected to the low pressure scan.
[0079] Generally on a coating-free, printing ink-free and impregnant-free
basis, the
volume average diameter of the pores of the microporous material is at least
0.02
micrometers, typically at least 0.04 micrometers, and more typically at least
0.05
micrometers. On the same basis, the volume average diameter of the pores of
the
microporous material is also typically less than or equal to 0.5 micrometers,
more
typically less than or equal to 0.3 micrometers, and further typically less
than or equal to
0.25 micrometers. The volume average diameter of the pores, on this basis, may
range
between any of these values, inclusive of the recited values. For example, the
volume
average diameter of the pores of the microporous material may range from 0.02
to 0.5
micrometers, or from 0.04 to 0.3 micrometers, or from 0.05 to 0.25
micrometers, in each
case inclusive of the recited values.
[0080] In the course of determining the volume average pore diameter by
means of
the above described procedure, the maximum pore radius detected may also be
determined. This is taken from the low pressure range scan, if run; otherwise
it is taken
from the high pressure range scan. The maximum pore diameter of the
microporous
material is typically twice the maximum pore radius.
[0081] Coating, printing and impregnation processes can result in filling
at least some
of the pores of the microporous material. In addition, such processes may also
irreversibly compress the microporous material. Accordingly, the parameters
with
respect to porosity, volume average diameter of the pores, and maximum pore
diameter
are determined for the microporous material prior to application of one or
more of these
processes.
[0082] Numerous art-recognized processes may be used to produce the
microporous
materials of the present invention. For example, the microporous material of
the present
invention can be prepared by mixing together filler particles, thermoplastic
organic
polymer powder, processing plasticizer and minor amounts of lubricant and
antioxidant,
until a substantially uniform mixture is obtained. The weight ratio of
particulate filler to
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polymer powder employed in forming the mixture is essentially the same as that
of the
microporous material to be produced. The mixture, together with additional
processing
plasticizer, is typically introduced into the heated barrel of a screw
extruder. Attached to
the terminal end of the extruder is a sheeting die. A continuous sheet formed
by the die is
forwarded without drawing to a pair of heated calender rolls acting
cooperatively to form
a continuous sheet of lesser thickness than the continuous sheet exiting from
the die. The
level of processing plasticizer present in the continuous sheet at this point
in the process
can vary and will effect the density of the final microporous sheet. For
example, the level
of processing plasticizer present in the continuous sheet, prior to extraction
as described
herein below, can be greater than or equal to 30 percent by weight of the
continuous
sheet, such as greater than or equal to 40 percent by weight, or greater than
or equal to 45
percent by weight of the continuous sheet prior to extraction. Also, the
amount of
processing plasticizer present in the continuous sheet prior to extraction can
be less than
or equal to 70 percent by weight of the continuous sheet, such as less than or
equal to 65
percent by weight, or less than or equal to 60 percent by weight, or less than
or equal to
57 percent by weight of the continuous sheet prior to extraction. The level of
processing
plasticizer present in the continuous sheet at this point in the process,
prior to extraction,
can range between any of these values inclusive of the recited values.
Generally, the
level of processing plasticizer can in one embodiment vary from 57 to 62
weight percent,
and in another embodiment be less than 57 weight percent.
[0083] The continuous sheet from the calender is then passed to a first
extraction zone
where the processing plasticizer is substantially removed by extraction with
an organic
liquid, which is a good solvent for the processing plasticizer, a poor solvent
for the
organic polymer, and more volatile than the processing plasticizer. Usually,
but not
necessarily, both the processing plasticizer and the organic extraction liquid
are
substantially immiscible with water. The continuous sheet then passes to a
second
extraction zone where residual organic extraction liquid is substantially
removed by
steam and/or water. The continuous sheet is then passed through a forced air
dryer for
substantial removal of residual water and remaining residual organic
extraction liquid.
From the dryer the continuous sheet, which is microporous material, is passed
to a take-
up roll.
[0084] The processing plasticizer is a liquid at room temperature and
usually is a
processing oil such as paraffinic oil, naphthenic oil, or aromatic oil.
Suitable processing
oils include those meeting the requirements of ASTM D 2226-82, Types 103 and
104.
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More typically, processing oils having a pour point of less than 220 C
according to
ASTM D 97-66 (re-approved 1978) are used to produce the microporous material
of the
present invention. Processing plasticizers useful in preparing the microporous
material of
the present invention are discussed in further detail in U.S. Pat. No.
5,326,391 at column
10, lines 26 through 50, which disclosure is incorporated herein by reference.
[0085] In an
embodiment of the present invention, the processing plasticizer
composition used to prepare the microporous material has little solvating
effect on the
polyolefin at 60 C, and only a moderate solvating effect at elevated
temperatures on the
order of 100 C. The processing plasticizer composition generally is a liquid
at room
temperature. Non-limiting examples of processing oils that may be used can
include
SHELLFLEX 412 oil, SHELLFLEX 371 oil (Shell Oil Co.), which are solvent
refined
and hydrotreated oils derived from naphthenic crude oils, ARCOprime 400 oil
(Atlantic
Richfield Co.) and KAYDOL oil (Witco Corp.), which are white mineral oils.
Other
non-limiting examples of processing plasticizers can include phthalate ester
plasticizers,
such as dibutyl phthalate, bis(2-ethylhexyl) phthalate, diisodecyl phthalate,
dicyclohexyl
phthalate, butyl benzyl phthalate, and ditridecyl phthalate. Mixtures of any
of the
foregoing processing plasticizers can be used to prepare the microporous
material of the
present invention.
[0086] There are
many organic extraction liquids that can be used to prepare the
microporous material of the present invention. Examples of suitable organic
extraction
liquids include those described in U.S. Pat. No. 5,326,391 at column 10, lines
51 through
57, which disclosure is incorporated herein by reference.
[0087] The
extraction fluid composition can comprise halogenated hydrocarbons,
such as chlorinated hydrocarbons and/or fluorinated hydrocarbons. In
particular, the
extraction fluid composition may include halogenated hydrocarbon(s) and have a
calculated solubility parameter coulomb term (&1b) ranging from 4 to 9 (Jcm3)1
/2. Non-
limiting examples of halogenated hydrocarbon(s) suitable as the extraction
fluid
composition for use in producing the microporous material of the present
invention can
include one or more azeotropes of halogenated hydrocarbons selected from trans-
1,2-
dichloroethy lene, 1,1,1,2,2,3 ,4,5,5,5- decafluoropentane, and/or
1,1,1,3,3-
pentafluorobutane. Such materials are available commercially as VERTREL MCA (a
binary azeotrope of 1,1,1,2,2,3,4,5,5,5-dihydrodecafluoropentane and trans-1,2-
dichloroethylene: 62%/38%), and VERTREL CCA (a ternary azeotrope of
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1,1,1,2,2,3,4,5,5,5-dihydrodecafluorpentane, 1,1,1,3,3-pentafluorbutane, and
trans-1,2-
dichloroethylene: 33%/28%/39%), both available from MicroCare Corporation.
[0088] The residual processing plasticizer content of microporous material
according
to the present invention is usually less than 10 percent by weight, based on
the total
weight of the microporous material, and this amount may be further reduced by
additional
extractions using the same or a different organic extraction liquid. Often the
residual
processing plasticizer content is less than 5 percent by weight, based on the
total weight
of the microporous material, and this amount may be further reduced by
additional
extractions.
[0089] The microporous material of the present invention may also be
produced
according to the general principles and procedures of U.S. Pat. Nos.
2,772,322;
3,696,061; and/or 3,862,030. These principles and procedures are particularly
applicable
where the polymer of the matrix is or is predominately poly(vinyl chloride) or
a
copolymer containing a large proportion of polymerized vinyl chloride.
[0090] Microporous materials produced by the above-described processes
optionally
may be stretched. Stretching of the microporous material typically results in
both an
increase in the void volume of the material, and the formation of regions of
increased or
enhanced molecular orientation. As is known in the art, many of the physical
properties
of molecularly oriented thermoplastic organic polymer, including tensile
strength, tensile
modulus, Young's modulus, and others, differ, e.g., considerably, from those
of the
corresponding thermoplastic organic polymer having little or no molecular
orientation.
Stretching is typically accomplished after substantial removal of the
processing plasticizer
as described above.
[0091] Various types of stretching apparatus and processes are well known
to those of
ordinary skill in the art, and may be used to accomplish stretching of the
microporous
material of the present invention. Stretching of the microporous materials is
described in
further detail in U.S. Pat. No. 5,326,391 at column 11, line 45 through column
13, line 13,
which disclosure is incorporated herein by reference.
[0092] The present invention is more particularly described in the
examples that
follow, which are intended to be illustrative only, since numerous
modifications and
variations therein will be apparent to those skilled in the art. Unless
otherwise specified,
all parts and percentages are by weight.
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EXAMPLES
In Part 1 of the following examples, the materials and methods used to prepare
the Example and Comparative mixes prepared in the pilot plant and presented in
Table 1
and the Example mixes prepared in the scale-up process and Comparative
commercial
samples presented in Table 2 are described. In Part 2, the methods used to
extrude,
calender and extract the sheets prepared from the mixes of Part 1 and Part 2
are described.
In Part 3, the methods used to determine the physical properties reported in
Tables 3 and
4 are described. In Parts 4A and 4B, the coating formulations used are listed
in Tables 5
and 7 and the properties of the coated sheets are listed in Tables 6 and 8. In
Part 5, The
Benzyl Acetate Test results for the products of Tables 1, 2, 6 and 8 are
listed in Tables 9,
10,11 and 12.
PART 1- MIX PREPARATION
The dry ingredients were weighed into a FM-130D Littleford plough blade
mixer with one high intensity chopper style mixing blade in the order and
amounts (grams
(g) specified in Table I. The dry ingredients were premixed for 15 seconds
using the
plough blades only. The process oil (Mix Oil) was then pumped in via a hand
pump
through a spray nozzle at the top of the mixer, with only the plough blades
running. The
pumping time for the examples varied between 45-60 seconds. The high intensity
chopper blade was turned on, along with the plough blades, and the mix was
mixed for 30
seconds. The mixer was shut off and the internal sides of the mixer were
scrapped down
to insure all ingredients were evenly mixed. The mixer was turned back on with
both
high intensity chopper and plough blades turned on, and the mix was mixed for
an
additional 30 seconds. The mixer was turned off and the mix dumped into a
storage
container.
-28-
TABLE 1
0
n.)
Samples Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6
Ex. 7 Ex. 8 Ex.11 CE 1 CE 2 CE 3 CE 4 CE 5
o
1-,
vi
Silica HiSil 135 (a) 1393 1393 1393 1393 0 0 1814 1814
1814 1393 1393 2270 2270 2270
Ca Silicate (b) 0.0 0.0 0.0 0.0 1816 1816 0.0 0.0
0.0 0.0 0.0 0.0 0.0 0.0 vi
o
CaCO3 (c) 544.3 544.3 544.3 544.3 709.0 709.0
0.0 0.0 0.0 544.3 544.3 0.0 0.0 0.0 -4
oe
TiO2 (d) 90.7 90.7 90.7 90.7 118.0 118.0 87.3
87.3 87.3 90.7 90.7 91.0 91.0 91.0 .6.
UHMWPE (e) 515.3 515.3 515.3 515.3 581.0 671.0
592.0 592.0 592.0 515.3 515.3 560.0 285.0 654.0
_ _
HDPE (f) 475.4 475.4 475.4 475.4 710.0 619.0
129.0 0.0 0.0 475.4 475.4 560.0 654.0 654.0
LDPE (g) 0.0 0.0 0.0 0.0 0.0 0.0 664.5 793.5
793.5 0.0 0.0 0.0 0.0 0.0
Antioxidant (h) 14.5 14.5 14.5 14.5 18.9 18.9
20.1 20.1 20.1 14,5 14.5 7.7 7.7 7.7
_
Lubricant (i) 14.5 14.5 14.5 14.5 18.9 18.9 21.6
21.6 21.6 14.5 14.5 22.7 22.7 22.7
Polypropylene (j) 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
0.0 0.0 0.0 185.0 370.0 0.0
CFA (k) 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
0.0 0.0 0.0 0.0 194.7
Nanoclay MB (1) 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0,
0.0 0.0 0.0 0.0 0.0 194.7
_
Mix oil (m) 2841 2841 2841 2841 931 885 2836 2836
2836 2841 2841 3655 3851 3850 9
Process Oil (%)
47.8% 48.0% 49.8% 52.6% 47.8% 47.2% 53.3% 56.0% 52.4% 55.9% 57.4% 60.5%
59.6% 57.7% .
r.,
r.,
u,
.3
(a) HI-SILO 135 precipitated silica from PPG Industries, Inc.
u,
r.,
(b) INHIBISIL75 precipitated calcium silicate from PPG Industries, Inc.
.
,
,
(c) Calcium carbonate from Camel White
.
,
(d) TIPUREO R-103 titanium dioxide from E.I. du Pont de Nemours and Company
(e) GUR014 4130 Ultra High Molecular Weight Polyethylene (UHMWPE), from Ticona
Corp.
(f) FINA 1288 High Density Polyethylene (HDPE), from Total Petrochemicals
(g) Petrothene NA206000 LDPE from Lyondell Basel
(h) CYANOX 1790 antioxidant from Cytec Industries, Inc.
(i) Calcium stearate lubricant, technical grade
(j) Used was PRO-FAX 7523 Polypropylene Copolymer from Ashland Distribution.
(k) Foam PE MB, a chemical foaming agent from Amacet Corporation
1-d
(1) NanoMax HDPE materbatch nanoclay from Nanocor
n
,-i
(m) Tufflo 6056 process oil from PPC Lubricants
c)
t..)
o
1-
.6.
-a
u,
-4
c.,
c.,
-4
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Scale-up Examples 10-18 were prepared in a plant scale-up batch size
using production scale equipment similar to the equipment and procedures
described
above. The scale-up samples were prepared from a mix of ingredients listed in
Table 2 as
the weight percent of the total mix.
TABLE 2
Ingredients Ex. 10 Ex. 11 Ex. 12 Ex 13 Ex. 14 Ex. 15 Ex. 16 Ex. 17 Ex. 18
HiSil 135 (a) 23.66 23.66 23.66 23.66 24.77 24.77 24.77 24.77 24.77 -
CaCO3 (c) 9.24 9.24 9.24 9.24 9.68 9.68 9.68 9.68
9.68
TiO2 (d) 1.54 1.54 1.54 1.54 1.61 1.61 1.61 1.61
1.61
UHNIWPE (e) 8.75 8.75 8.75 8.75 9.16 9.16 9.16 8.45
8.45
HDPE 8.07 8.07 8.07 8.07 8.45 8.45 8.45 9.16 9.16
Antioxidant (h) 0.25 0.25 0.25 0.25 0.26 0.26 0.26 0.26
0.26
Lubricant (i) 0.25 0.25 0.25 0.25 0.26 0.26 0.26
0.26 0.26
Mix Oil (m) 48.24 48.24 48.24 48.24 45.81 45.81 45.81 45.81 45.81 -
PART 2- EXTRUSION, CALENDERING AND EXTRACTION
The mixes of the Examples 1-9 and Comparative Examples 1-5 were extruded
and calendered into final sheet form using an extrusion system including a
feeding,
extrusion and calendering system described as follows. A gravimetric loss in
weight feed
system (K-tron model # K2MLT35D5) was used to feed each of the respective
mixes into
a 27mm twin screw extruder (model # was Leistritz Micro-27gg). The extruder
barrel
was comprised of eight temperature zones and a heated adaptor to the sheet
die. The
extrusion mixture feed port was located just prior to the first temperature
zone. An
atmospheric vent was located in the third temperature zone. A vacuum vent was
located
in the seventh temperature zone.
The mix was fed into the extruder at a rate of 90 g/minute. Various amounts of
additional processing oil also was injected at the first temperature zone, as
required, to
achieve the desired total oil content in the extruded sheet. The oil contained
in the
extruded sheet (extrudate) being discharged from the extruder is referenced
herein as the
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"extrudate oil" or "process oil", and is reported in weight percentin Table 1,
based on the
total weight of the extruded sheet. In accordance with an embodiment of the
present
invention, densities of greater than 0.8 g/cm3 of the microporous sheet are
obtained when
the amount of process oil (extrudate oil) in the extruded sheet is less than
57 weight
percent. While not wishing to be bound by any particular theory, it is
believed from the
experimental evidence at hand that lowering the amount of process oil in the
extruded
microporous sheet increases the density of the microporous sheet, e.g., to
greater than 0.8
g/cm3 and alters the surface of the sheet so that volatile material
transferred to the vapor
release surface is more dispersed and does not pool initially into droplets on
that surface.
Extrudate from the barrel was discharged into a 15-centimeter wide sheet
Masterflex die having a 1.5 millimeter discharge opening. The extrusion melt
temperature was 203-210 C and the throughput was 7.5 kilograms per hour.
The calendering process was accomplished using a three-roll vertical calender
stack with one nip point and one cooling roll. Each of the rolls had a chrome
surface.
Roll dimensions were approximately 41 cm in length and 14 cm in diameter. The
top roll
temperature was maintained between 135 C to 140 C. The middle roll temperature
was
maintained between 140 C to 145 C. The bottom roll was a cooling roll wherein
the
temperature was maintained between 10-21 C. The extrudate was calendered into
sheet
form and passed over the bottom water cooled roll and wound up.
A sample of sheet cut to a width up to 25.4 cm and length of 305 cm was rolled
up and placed in a canister and exposed to hot liquid 1,1,2-trichloroethylene
for
approximately 7-8 hours to extract oil from the sheet sample. Afterwards, the
extracted
sheet was air dried and subjected to test methods described hereinafter.
The mixes of the Scale-up Examples 10-18, as shown in Table 2, were extruded
and calendered into final sheet form using an extrusion system and oil
extraction process
that was a production sized version of the system described above, carried out
as
described in U.S. 5,196,262, at column 7, line 52, to column 8, line 47, which
description
is incorporated herein by reference. The final sheets were tested for physical
parameters
using the test methods described above in Part 3. Comparative Examples 6-10
were
commercial microporous products identified as follows: CE 6 was TESLIN
Digital 10
mil; CE 7 was Teslin SP 6mil; CE 8 was TESLIN SP 10mil; CE 9 was TESLIN SP
14mil; and CE 10 was TESLIN SP 12mil.
The extrudate oil (weight percent) for the commercial products used for
comparative examples 6-10 varied from 57 to 62 percent.
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PART 3¨ TESTING AND RESULTS
Physical properties measured on the extracted and dried films and the results
obtained are listed in Tables 3 and 4. The extrudate oil weight percent was
measured
using a Soxhlet extractor. The extrudate oil weight percent determination used
a
specimen of extrudate sheet with no prior extraction. A sample specimen
approximately
2.25 inches x 5 inches (5.72 cm x 12.7 cm) was weighed and recorded to four
decimal
places. Each specimen was then rolled into a cylinder and placed into a
Soxhlet
extraction apparatus and extracted for approximately 30 minutes using
trichloroethylene
(TCE) as the solvent. The specimens were then removed and dried. The extracted
and
dried specimens were then weighed. The oil weight percentage values
(extrudate) were
calculated as follows: Oil Wt. % = (initial wt. - extracted wt.) x 100 /
initial wt.
Thickness was determined using an Ono Sokki thickness gauge EG-225. Two
4.5 inches x 5 inch (11.43 cm x 12.7 cm) specimens were cut from each sample
and the
thickness for each specimen was measured in nine places (at least 3/4 of an
inch (1.91 cm)
from any edge). The arithmetic average of the readings was recorded in mils to
2 decimal
places and converted to microns.
The density of the above-described examples was determined by dividing the
average anhydrous weight of two specimens measuring 4.5 inches x 5 inches
(11.43 cm x
12.7 cm) that were cut from each sample by the average volume of those
specimens. The
average volume was determined by boiling the two specimens in deionized water
for 10
minutes, removing and placing the two specimens in room temperature deionized
water,
weighing each specimen suspended in deionized water after it has equilibrated
to room
temperature and weighing each specimen again in air after the surface water
was blotted
off. The average volume of the specimens was calculated as follows:
Volume (avg.) = [(weight of lightly blotted specimens weighed
in air - sum of immersed weights) x 1.0021/2
The anhydrous weight was determined by weighing each of the two specimens
on an analytical balance and multiplying that weight by 0.98 since it was
assumed that the
specimens contained 2 percent moisture.
The Porosity reported in Tables 3 and 4 was determined using a Gurley
densometer, model 4340, manufactured by GPI Gurley Precision Instruments of
Troy,
New York. The Porosity reported was a measure of the rate of air flow through
a sample
or it's resistance to an air flow through the sample. The unit of measure is a
"Gurley
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second" and represents the time in seconds to pass 100cc of air through a 1
inch square
(6.4 x 10-4 m2) area using a pressure differential of 4.88 inches of water
(12.2 x 102 Pa).
Lower values equate to less air flow resistance (more air is allowed to pass
freely). The
measurements were completed using the procedure listed in the manual, MODEL
4340
Automatic Densometer and Smoothness Tester Instruction Manual. TAPPI method T
460
om-06-Air Resistance of Paper can also be referenced for the basic principles
of the
measurement.
-33-
TABLE 3
0
tµ.)
Property Ex. 1 Ex. 2 Ex. 3
Ex. 4 Ex. 5 Ex. 6 Ex. 7 Ex. 8 Ex. 9 CE 1 CE 2 CE 3 CE 4
CE 5
Sheet Thickness 262 264 264 262 371 419 173 155 173
260 246 174 160 169
(11m)
Extrudate Oil wt. 47.8% 48.0% 49.8% 52.6% 47.8% 47.2% 53.5% 56.0% 52.4% 55.9%
57.4% 60.5% 59.6% 57.7% c'e
Density (g/cc) 0.764 0.828 0.755 0.707 0.892 0.901
0.646 0.612 0.701 0.750 0.695 0.584 0.659 0.620
Porosity (Gurley 2148 2161 2009 1988 1685 1730
3787 3735 4155 1842 1517 1473 1309 1410
Sec.)
TABLE 4
Property Ex. 10 Ex. 11
Ex. 12 Ex 13 Ex. 14 Ex. 15 Ex. 16
Ex. 17 Ex. 18 CE 6 CE 7 CE 8 CE 9 CE 10 p
Sheet Thickness (p,m) 291 293 269 286 289 288 278
277 284 284 157 250 359 306
Extrudate Oil wt. % 58.0% 57.6% 58.0% 57.1% 55.0% 53.5% 54.0% 54.0%
53.0%
Density (g/cc) 0.795 0.804 0.809 0.815 0.818 0.882
0.835 _ 0.835 0.862 0.719 0.607 0.677 0.691 0.672
Porosity (Gurley Sec.) 2877 3017 3395 3208 2800 2872
3048 2849 3102 5983 1867 3659 4110 4452
1-d
c7,
c7,
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PART 4 A- COATING FORMULATIONS AND COATED PRODUCTS
Coatings 1-5 listed in Table 5 were prepared by dispersing CELVOL 325
polyvinyl
alcohol in cool water under mild agitation in a 600 mL beaker. Mild agitation
was provided
with a 1" (2.54 cm) paddle stirrer driven by an electric stir motor. The
mixture was heated to
190 F (87.8 C) and stirred for 20 - 30 minutes. The resultant solution was
allowed to cool to
room temperature while stirring. Specific mix amounts and resultant measured
solids are
outlined in Table 5.
Table 5. Coating Formulations
CELVOL 325, Deionized water, Measured Solids,
Coating # (grams) (grams) % by weight
1 7.5 292.5 2.5 0.3
2 11.3 288.7 3.8 0.3
3 13.5 286.5 4.5 0.3
4 18.0 282.0 6.0 0.3
15.0 285.0 5.0 0.3
The coatings, confirmed to be free of visible undissolved particles, were
applied to TESLfN HD microporous substrate sold by PPG Industries,
Pittsburgh, Pa.
The coatings were applied to sheets of 8.5 inches x 11 inches, (21.59 cm x
27.94 cm) 11
mils thick substrate each of which had been tare on a balance prior to placing
the sheet on
a clean glass surface and using tape to adhere the top comers of the sheet to
the glass. A
piece of clear 10 mil thick polyester 11 inches x 3 inches (27.94 cm x 7.62
cm) was
positioned across the top edge of the sheet, covering 1/2 inch (1.27 cm) down
from the top
edge of the sheet. The polyester was fixed to the glass surface with tape. A
wire wrapped
metering rod from Diversified Enterprises was placed 1 - 2 inches (2.5 -5.1
cm) above
the sheet, parallel to the top edge, near the top edge of the polyester. A 10 -
20 mL
quantity of coating was deposited as a bead strip (approximately 1/4 inch
(0.64 cm) wide)
directly next to and touching the metering rod using a disposable pipette. The
bar was
drawn completely across the sheet, attempting a continuous/constant rate. The
resultant
wet sheet was removed from the glass surface, immediately placed on the
previously tare
balance, weighed, the wet coating weight recorded then the coated sheet was
placed in a
forced air oven and dried at 95 C for 2 minutes. The dried sheet was removed
from the
oven and the same coating procedure was repeated to the same coated sheet
surface. The
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two wet coating weights were used to calculate the final dry coat weight in
grams per
square meter. The coated sheets of Examples 19 ¨23 are described in Table 6.
Table 6. Final Coated Sheets
1st Wet 2nd Wet Total wet
Wire Coat Coat coating Calculated
Coating Wrapped Weight, Weight, weight, Final Coat
Example # Solids, % Rod # grams grams grams Weight, gsm
19 2.5 3 0.6 0.65 1.25 0.5 +0.1
20 3.8 3 0.61 0.59 1.20 0.75 +0.1
21 4.5 3 0.70 0.64 1.34 1.0 0.2
22 6 3 0.76 0.64 1.40 1.5 +0.1
23 5 10 1.18 1.20 2.38 2.1 0.2
The following formula was used to calculate the final dry coat weight.
Calculated Final Dry Coat Weight in grams per square meter = ((coatings solids
x
0.01) x (1st wet coating wgt. + 2nd wet coating wgt.))/(8.5x10.5) x 1550
PART 4B¨ COATING FORMULATIONS AND COATED PRODUCTS
The procedure of Part 4A was followed in preparing the coating formulations of
Coatings 6 ¨ 12, except that Coating 7 was mixed for 2 days prior to use. The
coating
formulations are listed in Table 7.
The substrate used in this Part 4B was TESLIN SP1000 microporous substrate
sold by PPG Industries, Pittsburgh, Pa. The same procedure used in Part 4A was
followed except that some sheets were coated on both sides, drying the first
coated side
prior to applying the second on the opposite side and a number 9 metering rod
was used
for all of the coatings. Information on the final coated sheets is included in
Table 8.
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Table 7. Coating Formulations with amounts listed in grams
Ingredients 6 7 8 9 10 11 12
Witcobond W240(,) 8 8 8 8 16 _ 0 0
Aerosile 200(0) 2.5 0 0 0 0 0 0
CaCO3(0) 0 2.5 0 0 0 0 0
HiSile T 700(p) 0 0 2.5 0 0 _ 0 0
Lo-Vel 6200(q) 0 0 0 2.5 0 0 0
MOIVIENTIVE LE-410(r) 0 0 0 0 0 0.54 0
HYCAR 26138(9) 0 0 0 0 0 0 10
Deionized Water 39.5 39.5 39.5 39.5
34.0 49.5 40
Total, grams 50 50 50 50 50 50 50
Solids, % 10 10 10 10 10 0.4 10
(n) WITCOBOND W-240, an aqueous polyurethane dispersion from Chemtura
Corporation.
(o) Aerosile 200 fumed silica from Degussa .
(p) HiSil eT700 precipitated silica from PPG Industries, Inc.
(q) Lo-Vel 86200 precipitated silica from PPG Industries, Inc.
(r) MOMENTIVE LE-410 an aqueous silicon dispersion from Momentive Performance
Materials.
(s) HYCAR 26138, an aqueous poly(meth)acrylate dispersion from Lubrizol
Advanced
Materials, Inc.
Table 8 Final Coated Sheets
Wet Coating weigh Final Coatim
Example # Coating # _ Coating Type (grams
weight (gsm:
24 10 Single 0.95 1.7
25 10 Both Sides 2.0 3.5
26 11 Both Sides 2.0 0.14
27 12 Both Sides 2.1 3.9
CE 11 11 Single 0.9 0.07
CE 12 12 Single 1.1 1.9
CE 13 6 Both Sides 2.2 3.8
CE 14 7 Both Sides 2.5 4.4
CE 15 8 Both Sides 2.3 3.9
CE 16 9 Both Sides 2.3 4.0
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PART 5¨ BENZYL ACETATE TESTING
The holder assembly used for evaporation rate and performance testing of a
membrane consisted of a front clamp with a ring gasket, a back clamp, test
reservoir cup
and four screws. The test reservoir cup was fabricated from a clear
thermoplastic
polymer, having interior dimensions defined by a circular diameter at the edge
of the
open face of approximately 4 centimeters and a depth of no greater than 1
centimeter.
The open face was used to determine the volatile material transfer rate.
Each clamp of the holder assembly had a 1.5 inch (3.8 cm) diameter circular
opening to accommodate the test reservoir cup and provide an opening to expose
the
membrane under test. When placing a membrane under test, i.e., a sheet of
microporous
material having a thickness of from 6 to 18 mils, the back clamp of the holder
assembly
was placed on top of a cork ring. The test reservoir cup was placed in the
back clamp and
charged with approximately 2 mL of benzyl acetate. An approximately 2inch (5.1
cm)
diameter disk was cut out of the membrane sheet and placed directly over and
in contact
with the edge of the reservoir cup such that 12.5 cm2 of the volatile material
contact
surface of the microporous sheet was exposed to the interior of the reservoir.
The front clamp of the holder was carefully placed over the entire assembly,
with the screw holes aligned and so as not to disturb the membrane disk. When
a coated
microporous sheet was used, the coated surface was placed either toward the
reservoir or
toward the atmosphere as indicated in the Table below. The screws were
attached and
- tightened enough to prevent leaking. The ring gasket created a seal. The
holder was
labeled to identify the membrane sample under test. From 5 to 10 replicates
were
prepared for each test. Five replicates of a Control (uncoated sample) was
included for
the coated Examples. For the Examples in Table 11, there were 5 Controls for
each
Example and the average evaporation rate for each Control was reported with
the
corresponding Example as well as the percent reduction in evaporation rate of
the
example compared to the corresponding Control. The coated surface of Example
19-23
in Table 11 was towards the atmosphere.
Each holder assembly was weighed to obtain an initial weight of the entire
charged assembly. The assembly was then placed, standing upright, in a
laboratory
chemical fume hood having approximate dimensions of 5 feet [1.52 meters]
(height) x 5
feet [1.52 meters] (width) x 2 feet [0.61 meters] (depth). With the test
reservoir standing
upright, benzyl acetate was in direct contact with at least a portion of the
volatile material
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contact surface of the microporous sheet. The glass doors of the fume hood
were pulled
down, and the air flow through the hood was adjusted so as to have eight (8)
turns (or
turnovers) of hood volume per hour. Unless otherwise indicated, the
temperature in the
hood was maintained at 25 C 5 C. The humidity within in the fume hood was
ambient.
The test reservoirs were regularly weighed in the hood. Testing was performed
for five
(5) days. The calculated weight loss of benzyl acetate, in combination with
the elapsed
time and surface area of the microporous sheet exposed to the interior of the
test
reservoir, were used to determine the volatile material transfer rate of the
microporous
sheet, in units of mg / (hour* cm2). The average evaporation rate (mg/hr) of
the replicates
was reported for the entire assembly in the Tables below. These two values are
related by
the following formula:
Average evaporation rate (mg/hr)/12.5cm2 = Volatile
Material transfer rate (mg/hour* cm2)
Marginal (Marg.) indicates that there were both passing and failing
replicates,
or that the test had no failures as described by "pooling" and "dripping" of
the benzyl
acetate down the surface of the membrane, but had some drops of benzyl acetate
forming
beads on the surface of the membrane, which was also deemed unacceptable vis-à-
vis, to
be graded as a "pass" result. There is, however, a clear performance
distinction between
a failing (FAIL) test result and a marginal (Marg.) test result, the latter
being clearly
superior, as discussed herein.
The date of Tables 2, 4 and 10 for Examples 10-18 and Comparative
Examples 6-10, which illustrate microporous sheets produced on production
scale
equipment, confirm the correlation between increased sheet density, which is
achieved by
lowering the amount of extrudate oil in the extruded sheet, and passing of the
benzyl
acetate test. This data is summarized in Table 13.
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Table 9
0
Samples
Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Ex. 7 Ex. 8 Ex. 9 CE 1
CE 2 CE 3 CE 4 CE 5
5 Day Results Pass Pass Pass Pass Pass Pass Pass
Pass Pass Fail Fail Fail Fail Fail
Evaporation 2.8 2.8 2.6 2.8 2.7 4.3 3.2 3.3 3.2 3.0 3.1 2.9 2.6 2.8
rate
TABLE 10
Samples Ex. 10 Ex. 11 Ex. 12 Ex 13 Ex. 14 Ex. 15 Ex. 16 Ex. 17 Ex. 18 CE 6
CE 7 CE 8 CE 9 CE 10
5 Day Results Marg. Marg. Marg. Marg. Pass Pass Pass Pass Pass
Fail Fail Fail Fail Fail
Evaporation 3.4 3.3 3.2 3.2 3.7 3.9 3.7 3.8
3.7 2.9 3.0 3.0 3.3 3.1
Rate
TABLE 11
Samples Ex. 19 Control Ex. 20 Control Ex. 21 Control
Ex. 22 Control Ex. 23 Control
Day Results Pass Fail Pass Fail Pass Fail
Pass Fail Pass Fail
Evaporation rate 4.09 4.65 3.61 4.69 2.05 4.10
2.68 4.69 1.25 4.03
Percent Reduction in 12 23 50 46
69
Evaporation Rate
1-d
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TABLE 12
0
Samples Control (1) Ex. 24 Ex. 24 Ex. 25 Control (4) Ex. 26 Ex. 27 CE 11
CE 12 CE CE 14 CE 15 CE 16
Ctr(2) Cta(3) Cta(3) Cta(3)
13
Day Results Fail Pass Pass Pass Fail Pass Pass Fail
Fail Fail Fail Fail Fail
Evaporation Rate 2.64 2.64 2.61 2.83 3.4 3.3 3.4
3.3 3.2 2.64 2.63 2.56 2.65
oe
(1) Control of uncoated TESLIN HD microporous material that was included with
Examples 24, 25, CE 13-16.
(2) Coated surface was directed toward reservoir of volatile material.
(3) Coated surface was directed toward the atmosphere.
(4) Control of uncoated TESLIN HD microporous material that was included with
Examples 26, 27, CE 11-12.
Table 13
Benzyl Acetate Sheet Density,
Extrudate Oil,
Example Set Test Result g/cc
weight %
Ex. 14-18 Pass 0.818 ¨ 0.882 53 - 55
Ex. 10-13 Marginal 0.795 ¨ 0.815 57-58
CE 6-10 Fail 0.607 ¨ 0.719 57-62
1-d
c7,
c7,
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Whereas particular embodiments of this invention have been described above
for purposes of illustration, it will be evident to those skilled in the art
that numerous
variations of the details of the present invention may be made without
departing from the
invention as defined in the appended claims.
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