HK1221431A1

HK1221431A1 - Microporous material

Info

Publication number: HK1221431A1
Application number: HK16109561.2A
Authority: HK
Inventors: ．博伊爾; J．L．博伊尔; ．加德納; C.加德纳; ．諾克斯; C.．L．诺克斯; ．帕裡尼洛; L．M．帕里尼洛; ．斯威舍; R．斯威舍
Original assignee: Ppg工业俄亥俄公司
Priority date: 2013-10-04
Filing date: 2014-09-26
Publication date: 2017-06-02
Also published as: BR112016007432A2; AU2014329889A1; WO2015050784A1; KR20160064225A; JP2016531965A; CA2925895A1; EP3052220A1; CN105745010A; TW201520232A; MX2016004289A

Abstract

Microporous materials that include thermoplastic organic polyolefin polymer (e.g., ultrahigh molecular weight polyolefin, such as polyethylene), particulate filler (e.g., precipitated silica), and a network of interconnecting pores, are described. The microporous materials of the present invention possess controlled volatile material transfer properties. The microporous materials can have a density of at least 0.8 g/cm3; and a volatile material transfer rate, from the volatile material contact surface to the vapor release surface of the microporous material, of from 0.04 to 0.6 mg / (hour* cm2). In addition, 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.

Description

Microporous material

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part application of U.S. patent application No. 13/473,001 filed on 16/5/2012 (now abandoned), which is a continuation of U.S. patent application No. 12/761,020 (now U.S. patent 8,435,631) filed on 15/4/2010, which are all incorporated herein by reference.

Technical Field

The present invention relates to microporous materials possessing controlled volatile material transfer properties. The microporous material includes a thermoplastic organic polymer, a particulate filler, and a network of interconnected pores.

Background

Delivery of volatile materials (such as fragrances, e.g., air fresheners) can be achieved by a delivery device that includes a reservoir containing the volatile material. The delivery device or delivery means typically comprises a vapour permeable membrane covering or enclosing 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 made from organic polymers and are porous.

The rate at which volatile materials pass through a vapor permeable membrane is often an important factor. For example, if the rate of passage of a volatile material through a vapor permeable membrane is too low, the properties associated with the volatile material (such as a fragrance) will typically be undesirably low or imperceptible. On the other hand, if the rate of passage of the volatile material through the vapor permeable membrane is too high, the volatile material reservoir may be depleted too quickly, and the properties associated with the volatile material (such as a fragrance) may be undesirably high, or in some cases too strong (overriding).

It is also generally desirable to minimize or avoid the formation of liquid volatile materials on the atmospheric side or outside 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 outside the vapor permeable membrane can collect (e.g., coagulate) within or outside the membrane and leak out of the delivery device, causing, for example, staining of an article (such as clothing or furniture) that is in contact with the liquid volatile material. In addition, the formation of liquid volatile material on the outside of the vapor permeable membrane can result in uneven release of the volatile material from the delivery device.

Further increases in ambient temperature can increase the rate at which volatile materials pass through the vapor permeable membrane to undesirably high rates. For example, delivery devices used in the passenger compartment of an automobile may be exposed to increased ambient temperatures. Therefore, it is typically desirable to minimize the increase in the rate at which volatile materials contained within the device pass through the vapor permeable membrane as a function of increasing ambient temperature.

It is desirable to develop new microporous materials with controlled volatile material transfer properties. It is further desirable that when such newly developed microporous materials are used as vapor permeable membranes for delivery devices, the microporous materials minimize the formation of liquid volatile materials on the outside or outer surface of the membrane. In addition, the rate of passage of volatile materials through such microporous materials should minimally increase with increasing ambient temperature.

Summary of The Invention

According to the present invention there is provided a microporous material comprising:

(a) a matrix of a substantially water-insoluble thermoplastic organic polymer, said organic polymer comprising a polyolefin;

(b) finely divided, substantially water-insoluble particulate filler distributed throughout said matrix and constituting from 40 to 90 weight percent, based on the total weight of said microporous material; and

(c) a network of interconnected pores substantially communicating throughout the microporous material;

wherein the microporous material has

At least 0.8g/cm³The density of (a) of (b),

the volatile material is in contact with the surface,

a vapor release surface, wherein the volatile material contact surface and the vapor release surface are substantially opposite one another, an

0.04 to 0.6 mg/(hr cm)²) The volatile material contact surface to the vapor release surface, and

wherein when volatile material is transferred from the volatile material contact surface to the vapour release surface (at 0.04 to 0.6 mg/(hour cm)²) A volatile material transfer rate) of the vapor release surface is substantially free of volatile material in liquid form.

Further, the present invention provides a microporous material comprising_：

wherein the microporous material has

Less than 0.8g/cm³The density of (a) of (b),

the volatile material is in contact with the surface,

a vapor release surface, wherein the volatile material contacting surface and the vapor release surface are substantially opposite one another, wherein (i) at least a portion of the volatile material contacting surface has a first coating thereon, and/or (ii) at least a portion of the vapor release surface has a second coating thereon,

Further, the present invention provides a microporous material comprising:

wherein the microporous material has a microporous structure having,

the volatile material is in contact with the surface,

a vapor release surface, wherein the volatile material-contacting surface and the vapor release surface are substantially opposite one another, wherein (i) at least a portion of the volatile material-contacting surface has a first coating thereon, and/or (ii) at least a portion of the vapor release surface has a second coating thereon, wherein the first coating and the second coating are each independently selected from a coating composition comprising poly (vinyl alcohol), and

at least 0.04 mg/(hr cm)²) The volatile material contact surface to the vapor release surface, and

wherein the volatile material transfer rate increases by less than or equal to 150% when the microporous material, i.e., the poly (vinyl alcohol) -coated microporous material, is exposed to an increase in temperature from 25 ℃ to 60 ℃.

Detailed Description

As used herein and in the claims, the term "volatile material contacting surface" means the surface of the microporous material that faces and is typically in contact with the volatile material, e.g., contained within a reservoir, as described in further detail below.

As used herein and in the claims, the term "vapor releasing surface" means a surface of the microporous material that does not face and/or directly contact the volatile material, and from which the volatile material is released into the external atmosphere in the form of a gas or vapor.

As used herein and in the claims, the term "(meth) acrylate" and similar terms such as an ester of (meth) acrylic acid "mean acrylate and/or methacrylate.

As used herein and in the claims, the "volatile material transfer rate" of a microporous material is determined according to the following description. A test reservoir having an internal volume sufficient to hold 2 milliliters of a volatile material, such as benzyl acetate, is made of a clear thermoplastic polymer. The internal dimensions of the reservoir are defined by a circular diameter of approximately 4cm at the edge of the opening face (openface) and a depth of no more than 1 cm. The open face is used to determine the volatile material transfer rate. With the test reservoir flat (with the open side facing up), about 2ml of benzyl acetate was introduced into the test reservoir. After benzyl acetate was introduced into the test reservoir, a sheet of microporous material having a thickness of 6 to 18 mils was placed on the open face/side of the test reservoir such that 12.5cm of the microporous sheet material²Is exposed to the interior of the reservoir. The test reservoir was weighed to obtain the starting weight of the entire charge assembly. The test reservoir, containing benzyl acetate and enclosed in a sheet of microporous material, was then placed upright having approximately 5 feet [1.52 meters ]](height) x5 feet [1.52 m ]](Width) x2 feet [0.61 m ]]Laboratory chemical fume hood of (depth) size. With the test reservoir upright, benzyl acetate was in direct contact with at least a portion of the volatile material contacting surface of the microporous sheet material. The glass door of a ventilated kitchen is pulled down and the air flow through the kitchen (hood) is adjusted so that there is a volume of the kitchen of eight (8) revolutions per hour (turn). Unless otherwise indicated, the temperature in the kitchen was maintained at 25 ℃. + -. 5 ℃. The humidity in the fume hood is ambient humidity. The test reservoir is weighed periodically in this kitchen. The calculated benzyl acetate weight loss combined with elapsed time and surface area of the microporous sheet exposed to the interior of the test reservoir were used to determine the volatility transfer rate of the microporous sheet in mg/(hr cm)²)。

As used herein and in the claims, the percent increase in volatile material transfer rate from 25 ℃ to 60 ℃ of the microporous material of the present invention is determined according to the above method for separate but substantially equivalent samples of microporous material sheet at 25 ℃ and 60 ℃. The reservoir was placed in a large glass bell jar and placed on a 50% aqueous solution of potassium chloride also contained in this bell jar. The entire bell jar with contents was placed in a furnace heated to 60 ℃. The reservoir was maintained under these conditions for a period of 7 to 10 hours. The reservoir is then returned to ambient conditions in a kitchen for overnight, and the process is repeated for several days. Each reservoir was weighed before being placed in the bell and after being removed from the bell. Upon removal from the bell jar, each reservoir was weighed after it had returned to ambient temperature.

As used herein and in the claims, the following method is used to determine whether the vapor releasing surface of the microporous material is "substantially free of volatile material in liquid form". When the test reservoir is weighed as described above, the vapor release surface of the microporous sheet is visually inspected by eye to determine if droplets of liquid and/or a film are present thereon. Microporous sheets are considered acceptable if any evidence of droplets (i.e., a single droplet) and/or film of liquid is visually observed on the vapor release surface but not flowing on the surface (runoff). If droplets of the volatile material liquid flow at the vapor release surface, the microporous sheet material is considered to have failed. If no evidence of a visual observation of a droplet of liquid (i.e., no one drop) and/or film on the vapor release surface is made, the microporous sheet material is determined to be substantially free of volatile material in liquid form.

Unless otherwise indicated, all ranges disclosed herein are to be understood to encompass any and all subranges subsumed therein. For example, a stated range of "1 to 10" should be considered to include any and all subranges 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, and so forth. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements, including those found in testing machines.

Unless otherwise indicated, all numbers or expressions (such as those expressing structural dimensions, amounts of ingredients, etc.) used in the specification and claims are to be understood as being modified in all instances by the term "about". Accordingly, unless indicated to the contrary, the numerical parameters set forth in this specification and attached claims are approximations that may 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. Furthermore, as used in this specification and the appended claims, the singular forms "a," "an," and "the" are intended to include plural references unless expressly and unequivocally limited to one reference.

The term "volatile material," as used herein and in the claims, means a material that is capable of being converted to a gas or vapor form (i.e., capable of being volatilized) at ambient room temperature and pressure and in the absence of imparted additional or supplemental energy (e.g., in the form of heat and/or agitation). The volatile materials can include organic volatile materials, which can include those volatile materials that comprise solvent-based materials, or those dispersed in solvent-based materials. The volatile materials can be in liquid form and/or solid form, and can be naturally occurring or synthetically formed. When in solid form, the volatile material typically sublimes from a solid form to a vapor form without passing through an intermediate liquid form. The volatile material can optionally be combined or formulated with a non-volatile material (such as a carrier, e.g., water and/or a non-volatile solvent). In the case of a solid volatile material, the non-volatile carrier can be in the form of a porous material, e.g., a porous inorganic material, within which the solid volatile material is retained. Further, the solid volatile material can be in the form of a semi-solid gel.

The volatile material may be a fragrance material, such as a naturally occurring or synthetic essential oil. Examples of essential oils that may be selected as the liquid volatile material include, but are not limited to, oils of bergamot, bitter orange, lemon, citrus, caraway, cedar leaf, clove leaf, cedar wood, geranium, lavender, orange, oregano, bitter orange leaf, cedar wood, patchouli, neroli, rose absolute, and combinations thereof. Examples of solid fragrance materials that may be selected as the volatile material include, but are not limited to, vanillin, ethyl vanillin, coumarin, tonalid, watermelon ketone (calone), sunflower essence (heliotropene), musk xylol, cedrol, musk ketone benzophenone, raspberry ketone, methyl naphthyl ketone beta, phenylethyl salicylate, meaty essence (veltol), maltitol, maple lactone, propulenol (proeugenol) acetate, oak moss (evemyl), and combinations thereof.

The microporous material can have a volatile material transfer rate of less than or equal to 0.7 mg/(hour cm)²) Or less than or equal to 0.6 mg/(hour cm)²) Or less than or equal to 0.55 mg/(hr cm)²) Or less than or equal to 0.50 mg/(hour cm)²). The microporous material may have a volatile material transfer of equal to or greater than 0.02 mg/(hour cm)²) Or equal to or greater than 0.04 mg/(hr cm)²) Or equal to or greater than 0.30 mg/(hr cm)²) Or equal to or greater than 0.35 mg/(hr cm)²). The microporous material can have a volatile material transfer rate ranging between any combination of these upper and lower values. For example, the microporous material may have a volatile material transfer rate of from 0.04 to 0.6 mg/(hour cm)²) Or from 0.2 to 0.6 mg/(hr cm)²) Or from 0.30 to 0.55 mg/(hr cm)²) Or from 0.35 to 0.50 mg/(hr cm)²) In each case including the stated values.

While not intending to be bound by any theory, it is believed that the volatile material is in a form selected from the group consisting of a liquid, a vapor, and combinations thereof, when the volatile material is transferred from the volatile material contacting surface of the microporous material to the vapor releasing surface. Furthermore, and without intending to be limited by any theory, it is believed that the volatile material moves at least partially through the network of interconnected pores that communicate substantially throughout the microporous material. Typically, the transfer of volatile material occurs at a temperature of from 15 ℃ to 40 ℃, e.g., from 15 or 18 ℃ to 30 or 35 ℃, and at ambient atmospheric pressure.

The microporous material can have at least 0.7g/cm³Or at least 0.8g/cm³The density of (c). As used herein and in the claims, the density of a 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 vary widely, provided that it has, for example, from 0.04 to 0.6 mg/(hour cm)²) 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 the vapor release surface. Typically, the density of the microporous material is less than or equal to 1.5g/cm³Or less than or equal to 1.0g/cm³. The density of the microporous material can be between any of the above values, inclusive of the recited values. For example, the microporous material may have a density of 0.7g/cm³To 1.5g/cm³A density of, e.g., 0.8g/cm³To 1.2g/cm³Including the values recited.

When the microporous material has at least 0.7g/cm³Such as, for example, at least 0.8g/cm³The volatile material contacting surface and the vapor releasing surface of the microporous material each may be free of coating material thereon. The volatile material contacting surface and the vapor-releasing surface are each defined by a microporous material when the coating material is absent thereon.

When the microporous material has at least 0.7g/cm³Such as, for example, at least 0.8g/cm³At least a portion of the volatile material contacting surface of the microporous material optionally can have a first coating thereon, and/or at least a portion of the vapor releasing surface of the microporous material optionally can 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-contacting surface has a first coating thereon, the volatile material-contacting surface is at least partially defined by the first coating. When at least a portion of the vapor release surface has a second coating thereon, the vapor release surface is at least partially defined by the second coating.

The first coating and the second coating can each be formed from a coating selected from the group consisting of a liquid coating and a solid particulate coating (e.g., a powder coating). Typically, the first and second coatings are each independently formed from a coating selected from a liquid coating, which may optionally include a solvent selected from water, organic solvents, and combinations thereof. Each of the first and second coatings independently can be selected from crosslinkable coatings, e.g., thermoset coatings and photocurable coatings; and non-crosslinkable coatings, for example, air-drying coatings. The first and second coatings may be applied to the respective surfaces of the microporous material according to art-recognized methods, such as spray coating, curtain coating, dip coating, and/or knife-coating (e.g., by a doctor-bar or drawdown bar) technique.

Each of the first and second coating compositions, independently, may 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 are therefore substantially transparent or opaque. The optional additives may be present in the coating composition in a separate amount, for example, from 0.01 to 10 weight percent, based on the total weight of the coating composition.

The first coating layer and the second coating layer each independently can be formed from an aqueous coating composition comprising a dispersed organic polymeric material. The aqueous coating composition may have a particle size of 200 to 400 nm. The solids of the aqueous coating composition can vary widely, for example, from 0.1 to 30 wt.%, or from 1 to 20 wt.%, based in each case on the total weight of the aqueous coating composition. The organic polymer comprising the aqueous coating composition can have, for example, a number average molecular weight (Mn) of from 1000 to 4,000,000, or from 10,000 to 2,000,000.

The aqueous coating composition may be selected from the group consisting of aqueous poly (meth) acrylate dispersions, aqueous polyurethane dispersions, aqueous silicone (or silicon) oil dispersions, and combinations thereof. The poly (meth) acrylate polymer of the aqueous poly (meth) acrylate dispersion may be prepared according to art-recognized methods. For example, the poly (meth) acrylate polymer may include residues (or monomer units) of alkyl (meth) acrylates having 1 to 20 carbon atoms in the alkyl group. Examples of alkyl (meth) acrylates having 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, isobornyl (meth) acrylate, cyclohexyl (meth) acrylate, and 3,3, 5-trimethylcyclohexyl (meth) acrylate. For non-limiting illustration purposes, an example of an aqueous poly (meth) acrylate dispersion from which the first and second coating compositions can each be independently selected is HYCAR26138, which is commercially available from lubrizol advanced materials, inc.

The polyurethane polymer of the aqueous polyurethane dispersion (from which the first and second coatings can each be independently selected) includes any of those known to those skilled in the art. Typically, the polyurethane polymer is prepared from an isocyanate functional material having two or more isocyanate groups, and an active hydrogen functional material having two or more active hydrogen groups. The active hydrogen groups can be selected from, for example, hydroxyl groups, thiol groups, primary amines, secondary amines, and combinations thereof. For non-limiting illustrative purposes, an example of an aqueous polyurethane dispersion (from which the first and second coating compositions may each be independently selected) is WITCOBONDW-240, which is commercially available from chemtura corporation.

The silicon polymer of the aqueous silicone oil dispersion may be selected from known and art-recognized aqueous silicone oil dispersions. For non-limiting illustrative purposes, an example of an aqueous silicon dispersion (from which the first and second coating compositions may each be independently selected) is momentive ele-410, which is commercially available from momentiveperformance materials.

The first coating layer and the second coating layer are eachIndependently, it may be applied at any suitable thickness, provided that the microporous material has, for example, from 0.04 to 0.6 mg/(hour cm)²) 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 the vapor release surface. Further, each of the first coating layer and the second coating layer independently can have 0.01 to 5.5g/m²Such as, for example, from 0.1 to 5.0g/m²Or from 0.5 to 3g/m²Or from 0.75 to 2.5g/m²Or from 1 to 2g/m²I.e., the coating weight on the microporous material.

The microporous material can have less than 0.8g/cm³And at least a portion of the volatile material contacting surface of the microporous material may have a first coating thereon, and/or at least a portion of the vapor releasing surface of the microporous material may have a second coating thereon. The first coating and the second coating can be the same or different, and each independently as previously described herein with respect to having at least 0.8g/cm³Optionally first and second coatings of microporous material.

When less than 0.8g/cm³When used, the microporous materials of the present invention may have any suitable lower limit on the density provided that the microporous material has, for example, from 0.04 to 0.6 mg/(hour cm)²) 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 the vapor release surface. In this particular embodiment of the invention, the density of the microporous material may be from 0.6 to less than 0.8g/cm³Or from 0.6 to 0.75g/cm³For example, from 0.60 to 0.75g/cm³Or from 0.6 to 0.7g/cm³For example, from 0.60 to 0.70g/cm³Or from 0.65 to 0.70g/cm³。

Further, at least a portion of the volatile material contacting surface of the microporous material can have a first coating thereon, and/or at least a portion of the vapor releasing surface of the microporous material can have a second coating thereon, wherein each of the first and second coatings is independently selected from a coating composition comprising poly (vinyl alcohol).

In the poly (vinyl alcohol) -coated embodiments of the present invention, the volatile material transfer rate of the microporous material, i.e., the poly (vinyl alcohol) -coated microporous material, increases by less than or equal to 150% when exposed to an increase in temperature from 25 ℃ to 60 ℃. When the poly (vinyl alcohol) -coated microporous material is exposed to increased temperatures from ambient temperatures, e.g., from 25 ℃ to 60 ℃, the volatile material transfer rate typically increases and typically does not decrease unless, for example, the microporous material has been damaged by exposure to higher ambient temperatures. Thus, and as used herein and in the claims, the statement that "its volatile material transfer rate increases by less than or equal to [ stated ] percent," e.g., 150%, includes the lower limit of 0%, but does not include the lower limit of less than 0%.

For illustrative purposes, when the poly (vinyl alcohol) -coated microporous material has a viscosity of 0.3 mg/(hr cm) at 25 ℃²) And when the microporous material is exposed to a temperature of 60 ℃, the volatile material transfer rate increases to less than or equal to 0.75 mg/(hour cm)²) The value of (c).

In one embodiment, the volatile material transfer rate of the microporous material, i.e., the poly (vinyl alcohol) -coated microporous material, increases by less than or equal to 125% when exposed to an increase in temperature from 25 ℃ to 60 ℃. For example, when the microporous material coated with poly (vinyl alcohol) has a viscosity of 0.3 mg/(hr cm) at 25 ℃²) And when the microporous material is exposed to a temperature of 60 ℃, the volatile material transfer rate increases to less than or equal to 0.68 mg/(hour cm)²) The value of (c).

Further, when the microporous material, i.e., the poly (vinyl alcohol) -coated microporous material, is exposed to an increase in temperature from 25 ℃ to 60 ℃, its volatile material transfer rate increases by less than or equal to 100%. For example, when the microporous material coated with poly (vinyl alcohol) has a surface tension at 25 ℃ of0.3 mg/(hr cm)²) And when the microporous material is exposed to a temperature of 60 ℃, the volatile material transfer rate increases to less than or equal to 0.6 mg/(hour cm)²) The value of (c).

The first and second poly (vinyl alcohol) coatings can each independently be present at any suitable coating weight, provided that the microporous material has, for example, at least 0.04 mg/(hour cm)²) And the volatile material transfer rate of the microporous material, i.e., the poly (vinyl alcohol) -coated microporous material, increases by less than or equal to 150% when exposed to an increase in temperature from 25 ℃ to 60 ℃. Typically, the first poly (vinyl alcohol) coating and the second poly (vinyl alcohol) coating each independently have 0.01 to 5.5g/m²Or from 0.1 to 4.0g/m²Or from 0.5 to 3.0g/m²Or from 0.75 to 2.0g/m²Coating weight of (c).

The poly (vinyl alcohol) -coated microporous material can have a volatile material transfer rate of at least 0.02 mg/(hr cm)²). The poly (vinyl alcohol) -coated microporous material can have a volatile material transfer rate of equal to or greater than 0.04 mg/(hour cm)²) Or equal to or greater than 0.1 mg/(hr cm)²) Or equal to or greater than 0.2 mg/(hr cm)²) Or equal to or greater than 0.30 mg/(hr cm)²) Or equal to or greater than 0.35 mg/(hr cm)²). The poly (vinyl alcohol) -coated microporous material can have a volatile material transfer rate of less than or equal to 0.7 mg/(hour cm)²) Or less than or equal to 0.6 mg/(hour cm)²) Or less than or equal to 0.55 mg/(hr cm)²) Or less than or equal to 0.50 mg/(hour cm)²). The volatile material transfer rate of the poly (vinyl alcohol) -coated microporous material can 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 cm)²) Such as, from 0.04 to 0.70 mg/(hour cm)²) Or from 0.04 to 0.60 mg/(hr cm)²) Or from 0.20 to 0.60 mg/(hour cm)²) Or from 0.30 to 0.55 mg/(hr cm)²) Or from 0.35 to 0.50 mg/(hr cm)²) In each case including the stated values.

The microporous material density of the poly (vinyl alcohol) -coated microporous material of embodiments of the present invention can vary widely, provided that the poly (vinyl alcohol) -coated microporous material has, for example, at least 0.04 mg/(hour x cm)²) And the volatile material transfer rate of the microporous material, i.e., the poly (vinyl alcohol) -coated microporous material, increases by less than or equal to 150% when exposed to an increase in temperature from 25 ℃ to 60 ℃.

Further, the microporous material density of the poly (vinyl alcohol) -coated microporous material can be at least 0.7g/cm³Such as, for example, at least 0.8g/cm³For example, from 0.8 to 1.2g/cm³All including the recited values. In one embodiment of the 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 0.8g/cm³. For example, the microporous material density of the poly (vinyl alcohol) -coated microporous material can be from 0.6 to less than 0.8g/cm³Or from 0.6 to 0.75g/cm³For example, from 0.60 to 0.75g/cm³Or from 0.6 to 0.7g/cm³For example, from 0.60 to 0.70g/cm³Or from 0.65 to 0.70g/cm³All including the recited values.

With respect to the poly (vinyl alcohol) -coated microporous material of the present invention, the vapor release surface is substantially free of volatile material in liquid form when the volatile material is transferred from the volatile material contact surface to the vapor release surface.

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., thermoset coatings; and non-crosslinkable coatings, for example, air-drying coatings. The poly (vinyl alcohol) coating can be applied to the various surfaces of the microporous material according to art-recognized methods, such as spraying, curtain coating, or knife coating, for example, by a knife or bar.

In one embodiment, the first and second poly (vinyl alcohol) coating layers are each independently formed from an aqueous poly (vinyl alcohol) coating composition. The solids of the aqueous poly (vinyl alcohol) coating composition can vary widely, for example, from 0.1 to 15 weight percent, or from 0.5 to 9 weight percent, based in each case on the total weight of the aqueous coating composition. The poly (vinyl alcohol) polymer of the poly (vinyl alcohol) coating composition can have, for example, a number average molecular weight (Mn) of from 100 to 1,000,000, or from 1000 to 750,000.

The poly (vinyl alcohol) polymer of the poly (vinyl alcohol) coating composition can be a homopolymer or a copolymer. Comonomers from which poly (vinyl alcohol) copolymers can be prepared include those that can be copolymerized with vinyl acetate (by free radical polymerization) and are known to those skilled in the art. For illustrative purposes, comonomers that can be used to prepare the poly (vinyl alcohol) copolymer include, but are not limited to: (meth) acrylic acid, maleic acid, fumaric acid, crotonic acid, their metal salts, their alkyl esters, e.g. C₂-C₁₀Alkyl esters, their polyethylene glycol esters, and their polypropylene glycol esters; vinyl chloride; tetrafluoroethylene; 2-acrylamido-2-methyl-propanesulfonic acid and its salts; (ii) acrylamide; an N-alkyl acrylamide; n, N-dialkyl substituted acrylamides; and N-vinylformamide.

For non-limiting illustrative purposes, an example of a poly (vinyl alcohol) coating composition that can be used to form the poly (vinyl alcohol) -coated microporous material of the present invention is CELVOL325, which is commercially available from sekisui specialty chemicals.

Each of the first and second poly (vinyl alcohol) coating compositions can 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 therefore transparent or opaque. The optional additives may be present in the poly (vinyl alcohol) coating composition in a separate amount, for example, from 0.01 to 10 weight percent, based on the total weight of the coating composition.

The matrix of the microporous material comprises a substantially water-insoluble thermoplastic organic polymer. The number and type of such polymers suitable for use as the matrix is large. Generally, any substantially water-insoluble thermoplastic organic polymer that can be extruded, calendered, pressed, or rolled (rolinto) into a film, sheet, strip, or web can be used. The polymer may be a single polymer, or it may be a mixture of polymers. The polymer can be a homopolymer, copolymer, random copolymer, block copolymer, graft copolymer, atactic polymer, isotactic polymer, syndiotactic polymer, linear polymer, or branched polymer. When a mixture of polymers is used, the mixture may be homogeneous or it may comprise two or more polymer phases.

Examples of suitable classes of 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 polymer may be selected include, for example, thermoplastic poly (urethane-urea) classes, poly (ester-amide) classes, poly (silane-siloxane) classes, and poly (ether-ester) classes. Further examples of suitable substantially water-insoluble thermoplastic organic polymers include thermoplastic high density polyethylene, low density polyethylene, ultra high 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 chloride and vinyl chloride, copolymers of ethylene and propylene, copolymers of ethylene and butylene, poly (vinyl acetate), polystyrene, poly (omega-aminoundecanoic acid), poly (hexamethylene adipamide), poly (-caprolactam), and poly (methyl methacrylate). The list of such categories and examples of substantially water-insoluble thermoplastic organic polymers is not exhaustive, but is provided for illustrative purposes only.

The substantially water-insoluble thermoplastic organic polymer may include, for example, poly (vinyl chloride), copolymers of vinyl chloride, or mixtures thereof. In one embodiment, the water insoluble thermoplastic organic polymer comprises an ultra high molecular weight polyolefin selected from the group consisting of: an ultra-high molecular weight polyolefin having an intrinsic viscosity of at least 10 deciliters/gram, e.g., a substantially linear ultra-high molecular weight polyolefin; or an ultra-high molecular weight polypropylene having an intrinsic viscosity of at least 6 deciliters/gram, e.g., a substantially linear ultra-high molecular weight polypropylene; or mixtures thereof. In a particular embodiment, the water-insoluble thermoplastic organic polymer comprises ultra-high molecular weight polyethylene, e.g., linear ultra-high molecular weight polyethylene, having an intrinsic viscosity of at least 18 deciliters/gram.

Ultra-high molecular weight polyethylene (UHMWPE) is not a thermosetting polymer with infinite molecular weight, but is technically classified as a thermoplastic. However, because the molecules are essentially very long chains, UHMWPE softens when heated, but does not flow in a generally thermoplastic manner as a molten liquid. The very long chains and the particular properties they provide to the UHMWPE are believed to contribute to a large extent to the desirable properties of the microporous material made using the polymer.

As indicated previously, the UHMWPE has an intrinsic viscosity of at least about 10 deciliters/gram. Typically, 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 limitation on the upper limit of the intrinsic viscosity, the intrinsic viscosity is often in the range of from about 10 to about 39 deciliters/gram, for example, in the range of from about 14 to about 39 deciliters/gram. In most cases, the intrinsic viscosity of UHMWPE ranges from about 18 to about 39 deciliters/gram, typically about 18 to about 32 deciliters/gram.

The nominal molecular weight of UHMWPE is empirically related to the intrinsic viscosity of the polymer according to the equation:

M(UHMWPE)＝5.3x10⁴[η]^1.37

wherein M (UHMWPE) is the nominal molecular weight and [ η ] is the intrinsic viscosity of the UHMW polyethylene, expressed in deciliters per gram.

As used herein and in the claims, intrinsic viscosity is determined by extrapolating the reduced viscosity or intrinsic viscosity of several diluted solutions of UHMWPE to zero concentration, where the solvent is freshly distilled decahydronaphthalene to which 0.2% by weight of 3, 5-di-tert-butyl-4-hydroxyhydrocinnamic acid, neopentanetetrayl ester [ CAS accession No. 6683-19-8] has been added. The reduced or intrinsic viscosity of UHMWPE is determined from the relative viscosity obtained at 135 ℃ using an ubpelohde No.1 viscometer according to the general procedure of astm d4020-81, except that several dilute solutions having different concentrations are used. Astm d4020-81 is hereby incorporated by reference in its entirety.

In a particular embodiment, the matrix comprises a mixture of substantially linear ultra high molecular weight polyethylene having an intrinsic viscosity of at least 10 deciliters/gram, and a Lower Molecular Weight Polyethylene (LMWPE) having an astm d1238-86 condition E melt index of less than 50 grams/10 minutes and an astm d1238-86 condition F melt index of at least 0.1 grams/10 minutes. The nominal molecular weight of LMWPE is lower than the nominal molecular weight of UHMW polyethylene. LMWPE is thermoplastic and many different types are known. According to astm d1248-84 (re-approved in 1989), one classification method is by density in grams/cubic centimeter, and rounded to the nearest thousandths, as outlined below:

any or all of these polyethylenes may be used as LMWPE in the present invention. For some applications, HDPE may be used because it generally tends to be more linear than MDPE or LDPE. Astm d1248-84 (re-approval 1989) is hereby incorporated by reference in its entirety.

The processes for making various LMWPEs are well known and well documented. They include the high pressure process, the Phillips styrene company process, the StandardOilcompany (Indiana) process, and the Ziegler process.

LMWPE has an ASTM D1238-86 Condition E (i.e., 190 ℃ C. and 2.16 kilogram load) melt index of less than about 50 grams/10 minutes. Typically, condition E melt index is less than about 25 g/10 min. Typically, condition E melt index is less than about 15 g/10 min.

LMWPE has an ASTM D1218-86 condition F (i.e., 190 ℃ C. and 21.6 kilogram load) melt index of at least 0.1 g/10 min. In many cases, condition F melt index is at least about 0.5 g/10 min. Typically, condition F has a melt index of at least about 1.0 g/10 min. Astm d1238-86 is hereby incorporated by reference in its entirety.

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, provided that their presence does not substantially affect the properties of the microporous material in a deleterious manner. One or more other thermoplastic polymers may be present in the matrix. The amount of other thermoplastic polymers that may be present depends on the nature of such polymers. Examples of thermoplastic organic polymers that 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 part of the carboxyl groups of the carboxyl-containing copolymer may be neutralized with sodium, zinc, or the like.

In most cases, the UHMWPE and LMWPE together constitute at least about 65 wt% of the polymer of the matrix. Typically, the UHMWPE and LMWPE together constitute at least about 85% by weight of the polymer of the matrix. Typically, substantially no other thermoplastic organic polymer is present, such that the UHMWPE and LMWPE together constitute substantially 100 wt% of the polymer of the matrix.

The UHMWPE may constitute at least 1 wt% of the polymer of the matrix. In the case where the UHMWPE and LMWPE together constitute 100 wt% of the polymer of the matrix of the microporous material, the UHMWPE may constitute greater than or equal to 40 wt% of the polymer of the matrix, such as greater than or equal to 45 wt%, or greater than or equal to 48 wt%, or greater than or equal to 50 wt%, or greater than or equal to 55 wt% of the polymer of the matrix. Further, the UHMWPE may constitute less than or equal to 99 wt% of the polymer of the matrix, such as less than or equal to 80 wt%, or less than or equal to 70 wt%, or less than or equal to 65 wt%, or less than or equal to 60 wt% of the polymer of the matrix. The UHMWPE content of the matrix-containing polymer may range between any of these values, inclusive of the recited values.

Likewise, in the case where the UHMWPE and the LMWPE together constitute 100 wt% of the polymer of the matrix of the microporous material, the LMWPE may constitute greater than or equal to 1 wt% of the polymer of the matrix, such as, for example, greater than or equal to 5 wt%, or greater than or equal to 10 wt%, or greater than or equal to 15 wt%, or greater than or equal to 20 wt%, or greater than or equal to 25 wt%, or greater than or equal to 30 wt%, or greater than or equal to 35 wt%, or greater than or equal to 40 wt%, or greater than or equal to 45 wt%, or greater than or equal to 50 wt%, or greater than or equal to 55 wt% of the polymer of the matrix. Further, the LMWPE may constitute less than or equal to 70 wt% of the polymer of the matrix, such as less than or equal to 65 wt%, or less than or equal to 60 wt%, or less than or equal to 55 wt%, or less than or equal to 50 wt%, or less than or equal to 45 wt% of the polymer of the matrix. The LMWPE content may range between any of these values, including the recited values.

It should be noted that for any of the foregoing microporous materials of the present invention, the LMWPE may comprise high density polyethylene.

The microporous material also includes a finely divided substantially water-insoluble particulate filler material. The particulate filler material may comprise an organic particulate material and/or an inorganic particulate material. The particulate filler material is typically uncoloured, for example, the particulate filler material is a white or off-white particulate filler material, such as a siliceous or clay particulate material.

Finely divided substantially water-insoluble filler particles may constitute from 20 to 90% by weight of the microporous material. For example, such filler particles may constitute 30% to 90% by weight of the microporous material, or 40 to 85% by weight of the microporous material, e.g., 45 to 80% by weight, or 50 to 80% by weight of the microporous material, e.g., 50 to 65, 70 or 75% by weight, and even 60% to 90% by weight of the microporous material.

The finely divided substantially water-insoluble particulate filler may be in the form of primary particles (ultimatparticles), aggregates of primary particles, or a combination of both. At least about 90% by weight of the filler used to make the microporous material has a total particle size (grisspaticlesize) ranging from 0.5 to about 200 microns, such as from 1 to 100 microns, as determined by LS230 using a laser diffraction particle sizer from beckmann coulton capable of measuring particle diameters as small as 0.04 microns. Typically, at least 90 wt% of the particulate filler has a total particle size ranging from 5 to 40 microns, for example, 10 to 30 microns. The size of the filler aggregates can be reduced during processing of the ingredients used to make the microporous material. Thus, the distribution of the total particle size within the microporous material may be less than the original filler itself.

Non-limiting examples of suitable organic and inorganic particulate materials that can be used in the microporous materials of the present invention include those described in U.S.6,387,519b1, column 9, line 4 to column 13, line 62, the citations of which are incorporated herein by reference.

In a particular embodiment of the invention, the particulate filler material comprises a siliceous material. Non-limiting examples of siliceous fillers that can be used to prepare the microporous material include silica, mica, montmorillonite, kaolinite, nanoclay (such as cloisite available from southern clay products), talc, diatomaceous earth, vermiculite, natural and synthetic zeolites, calcium silicate, aluminum silicate, sodium aluminum silicate, aluminum polysilicate, alumina silica gel, and glass particles. In addition to siliceous fillers, other finely divided particulate substantially insoluble fillers may optionally be used. Non-limiting examples of such optional particulate fillers include carbon black, charcoal, graphite, titanium oxide, iron oxide, copper oxide, zinc oxide, antimony oxide, zirconium oxide, magnesium oxide, aluminum oxide, molybdenum disulfide, zinc sulfide, barium sulfate, strontium sulfate, calcium carbonate, and magnesium carbonate. Some such optional fillers are color-producing fillers, and depending on the amount used, a hue (hue) or color may be added to the microporous material. In one non-limiting embodiment, the siliceous filler can include silica and any of the foregoing clays. Non-limiting examples of silica include precipitated silica, silica gel, fumed silica, and combinations thereof.

Silica gels are typically produced commercially by acidifying an aqueous solution of a soluble metal silicate (e.g., sodium silicate) with an acid at low pH. The acid used is typically a strong mineral acid such as sulfuric acid or hydrochloric acid, although carbon dioxide may be used. Since there is substantially no difference in density between the gel phase and the surrounding liquid phase at low viscosity, the gel phase does not settle, i.e., does not precipitate. Thus, silica gel can be described as a non-precipitated, adherent (coherent), rigid, three-dimensional network of adjacent colloidal amorphous silica particles. The finely divided state ranges from large solid matter (mass) to submicron particles and the degree of hydration ranges from almost anhydrous silica to soft gel materials containing about 100 parts by weight water per part by weight silica.

Precipitated silicas are typically produced commercially by combining an aqueous solution of a soluble metal silicate, a common alkali metal silicate (such as sodium silicate), and an acid such that colloidal silica particles 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 can 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, the silica does not precipitate from solution at any pH. In a non-limiting embodiment, the coagulant used to effect precipitation of the silica may be a 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.

Many different precipitated silicas are useful as siliceous fillers for making microporous materials. Precipitated silicas are well known commercial materials and methods for their production are described in detail in a number of U.S. patents, including U.S. patent nos. 2,940,830 and 4,681,750. The precipitated silica used to prepare the microporous material typically has an average primary particle size (whether or not the primary particles are aggregated) of less than 0.1 micron, e.g., less than 0.05 micron or less than 0.03 micron, as determined by transmission electron microscopy. Precipitated silicas are available in many grades and forms from ppginindustries, inc. These silicas are prepared byAnd selling under the trademark name.

For the purposes of the present invention, finely divided particulate substantially water-insoluble siliceous filler may constitute at least 50% by weight of the substantially water-insoluble filler material, for example, at least 65 or at least 75% by weight, or at least 90% by weight. The siliceous filler may comprise 50 to 90 percent by weight of the particulate filler material, for example, from 60 to 80 percent by weight, or the siliceous filler may comprise substantially all of the water-insoluble particulate filler material.

Particulate fillers, such as siliceous fillers, typically have a high surface area that enables the filler to be loaded with a number of processing plasticizer compositions used to make the microporous materials of the present invention. High surface area fillers are materials with very small particle sizes, materials with high porosity, or materials that exhibit both properties. Tables of particulate fillers (e.g., siliceous filler particles) as determined by the Brunauer, Emmett, Teller (BET) method according to ASTM D1993-91The area may range from 20 or 40 to 400 square meters per gram, for example, from 25 to 350 square meters per gram, or from 40 to 160 square meters per gram. The BET surface area can be determined by using a micromeritics TriStar3000^TMNitrogen adsorption isotherm measurements performed by the instrument were determined by fitting to five relative pressure points. FlowPrep-060^TMThe station may be used to provide heat and a continuous flow of gas during sample preparation. Prior to nitrogen adsorption, the silica sample was dried by heating to 160 ℃ for 1 hour in flowing nitrogen (PS). Typically, 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 substantially insoluble in any organic processing liquid used to prepare the microporous material. This promotes retention of the particulate filler within the microporous material.

The microporous materials of the present invention may also include small amounts (e.g., less than or equal to 5 weight percent) of other materials used for processing, such as lubricants, processing plasticizers, organic extraction liquids, water, and the like, based on the total weight of the microporous material. Additional materials introduced for particular purposes (such as thermal, ultraviolet, and dimensional stability) may optionally be present in the microporous material in small amounts, for example, less than or equal to 15 weight percent, based on the total weight of the microporous material. Examples of such additional materials include, but are not limited to, antioxidants, ultraviolet light absorbers, reinforcing fibers (such as chopped strands of glass fibers), and the like. The balance of the microporous material, excluding the filler and any coatings, printing inks, or impregnants applied for one or more particular purposes, is essentially a thermoplastic organic polymer.

The microporous materials of the present invention also include a network of interconnected pores that communicate substantially throughout the microporous material. When made as further described herein, the pores typically constitute from 35 to 95 volume percent based on the total volume of the microporous material, based on the uncoated, non-printing ink, non-saturant basis. The pores may constitute from 60 to 75 volume percent of the microporous material, based on the total volume of the microporous material. As used herein and in the claims, the porosity (also referred to as void volume) in volume percent of a microporous material is determined according to the following equation:

porosity of 100[1-d₁/d₂]

Wherein d is₁Is the density of the sample, which is determined from the sample weight and sample volume (as confirmed from measurement of the sample size); and d is₂Is the density of the solid portion of the sample, which is determined from the sample weight and sample volume of the solid portion of the sample. The volume of the solid portion of the microporous material was determined using a Quantachrome stereospeciometer (Quantachrome corp.) according to the operating manual accompanying the instrument.

The volume mean diameter of the pores of the microporous material is determined by mercury porosimetry using an Autoscan mercury porosimeter (quantachrome corp.) according to the operating manual accompanying this instrument. The volume average pore radius of a single scan is automatically determined by this porosimeter. In operating porosimeters, scanning is performed at high pressure ranges, from 138 kilopascals (absolute) to 227 megapascals (absolute). If 2% or less of the total intrusion volume occurs at the low end of the high pressure range (lowend) (from 138 to 250 kpa (absolute)), the volume average pore diameter is taken to be twice the volume average pore radius determined by a porosimeter. Otherwise, additional scans were performed at low pressure ranges (from 7 to 165 kilopascals (absolute)) and the volume average pore diameter was calculated according to the following equation:

d＝2[v₁r₁/w₁+v₂r₂/w₂]/[v₁/w₁+v₂/w₂]

wherein d is the volume average pore diameter; v. of₁Is the total volume of mercury that intrudes in the high pressure range; v. of₂Is the total volume of mercury that intrudes in the low pressure range; r is₁Is the volume average pore radius determined by high pressure scanning; r is₂Is the volume average pore radius determined by the low pressure scan; w is a₁Is the weight of the sample subjected to the high pressure scan; and w₂Is the weight of the sample subjected to the low pressure scan.

Generally, the volume average diameter of the pores of the microporous material is at least 0.02 microns, typically at least 0.04 microns, and more typically at least 0.05 microns, on an uncoated, non-printing ink, and non-impregnant basis. The volume average diameter of the pores of the microporous material is also typically less than or equal to 0.5 microns, more typically less than or equal to 0.3 microns, and further typically less than or equal to 0.25 microns, on the same basis. On this basis, the volume average diameter of the pores 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 microns, or from 0.04 to 0.3 microns, or from 0.05 to 0.25 microns, including the values recited in each case.

During the determination of the volume average pore diameter by the above procedure, the maximum pore radius detected may also be determined. This is taken from the low pressure range scan, if performed; otherwise from the high voltage range scan. The maximum pore diameter of the microporous material is typically twice the maximum pore radius.

The coating, printing, and impregnation methods result in filling at least some of the pores of the microporous material. Furthermore, such methods may also irreversibly compress the microporous material. Thus, parameters relating to porosity, volume average diameter of pores, and maximum pore diameter are determined for the microporous material prior to applying one or more of these methods.

Many art-recognized methods can be used to produce the microporous materials of the present invention. For example, the microporous material of the present invention may be prepared by mixing together filler particles, thermoplastic organic polymer powder, processing plasticizer, and small amounts of lubricant and antioxidant until a substantially homogeneous mixture is obtained. The weight ratio of particulate filler to polymer powder used to form the mixture is substantially the same as that of the microporous material to be produced. The mixture, along with additional processing plasticizer, is typically introduced into the heating barrel of a screw extruder. Attached to the end of the extruder is a sheeting die. The continuous sheet formed by this die is advanced without stretching to a pair of heated calender rolls that work together to form a continuous sheet having a smaller thickness than the continuous sheet exiting the die. The amount of processing plasticizer present in the continuous sheet at this point in the process may vary and affect the density of the final microporous sheet. For example, the processing plasticizer present in the continuous sheet prior to extraction as described below may be greater than or equal to 30 wt% of the continuous sheet, such as greater than or equal to 40 wt%, or greater than or equal to 45 wt% of the continuous sheet prior to extraction. Further, the amount of processing plasticizer present in the continuous sheet prior to extraction can be less than or equal to 70 weight percent of the continuous sheet, such as less than or equal to 65 weight percent, or less than or equal to 60 weight percent, or less than or equal to 57 weight percent of the continuous sheet prior to extraction. The amount of processing plasticizer present in the continuous sheet at this point in the process prior to extraction may range between any of these values, inclusive of the recited values. Generally, the processing plasticizer content may vary from 57 to 62 weight percent in one embodiment, and less than 57 weight percent in another embodiment.

The continuous sheet from the calender is then sent 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 is more volatile than the processing plasticizer). Typically, but not necessarily, both the processing plasticizer and the organic extraction liquid are substantially immiscible with water. The continuous sheet is then sent 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 to substantially remove residual water and residual organic extraction liquid. From the dryer, the continuous sheet (which is a microporous material) is sent to a take-up roll.

The processing plasticizer is liquid at room temperature and is typically a processing oil, such as a paraffinic oil, naphthenic oil, or aromatic oil. Suitable processing oils include those that meet the requirements of astm d2226-82, types 103 and 104. More typically, process oils having pour points of less than 220 ℃ according to ASTM D97-66 (approved again 1978) are used to produce the microporous materials of the present invention. Processing plasticizers useful in preparing the microporous materials of the present invention are discussed in further detail in U.S. patent No. 5,326,391, column 10, lines 26 through 50, the disclosure of which is incorporated herein by reference.

In one embodiment of the invention, the processing plasticizer composition used to prepare the microporous material has little solvating effect on the polyolefin at 60 ℃ and a moderate solvating effect at high temperatures of about 100 ℃. The processing plasticizer composition is typically a liquid at room temperature. Non-limiting examples of process oils that may be used may include412 oil, a,371 oil (ShellOilCo.), which are solvent refined and hydrotreated oils derived from naphthenic type crude oil,400 oil (Atlantic RichfilCo.) andoils (WitcoCorp.) they are white mineral oils. Other non-limiting examples of processing plasticizers may include phthalate 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 may be used to prepare the microporous materials of the present invention.

There are many organic extraction liquids that can be used to prepare the microporous materials of the present invention. Examples of suitable organic extraction liquids include those described in U.S. patent No. 5,326,391, column 10, lines 51 to 57, the disclosure of which is incorporated herein by reference.

The extraction fluid composition may comprise halogenated hydrocarbons, such as chlorinated hydrocarbons and/or fluorinated hydrocarbons. In particular, the extraction fluid composition may comprise halogenated hydrocarbons and have a range from 4 to 9 (Jcm)³)^1/2The calculated solubility parameter coulomb term (clb). Non-limiting examples of halogenated hydrocarbons suitable as extraction fluid compositions for producing microporous materials of the present invention may include one or more azeotropes of halogenated hydrocarbons selected from trans-1, 2-dichloroethylene, 1,1,1,2,2,3,4,5,5, 5-decafluoropentane, and/or 1,1,1,3, 3-pentafluorobutane. Such materials are commercially available from VERTRELMCA (binary azeotrope of 1,1,1,2,2,3,4,5,5, 5-dihydrodecafluoropentane and trans-1, 2-dichloroethylene: 62%/38%) and VERTRELCCA (ternary azeotrope of 1,1,1,2,2,3,4,5,5, 5-dihydrodecafluoropentane, 1,1,1,3, 3-pentafluorobutane, and trans-1, 2-dichloroethylene: 33%/28%/39%), both available from MicroCarecorporation.

The residual processing plasticizer content of the microporous material according to the present invention is typically less than 10 wt.%, based on the total weight of the microporous material, and this content can be further reduced by additional extraction using the same or different organic extraction liquids. Typically, the residual processing plasticizer content is less than 5 weight percent based on the total weight of the microporous material, and this content can be further reduced by additional extraction.

The microporous materials of the present invention may also be prepared according to U.S. patent nos. 2,772,322; 3,696,061, respectively; and/or 3,862,030. These principles and procedures are particularly applicable where the polymer of the matrix is or is predominantly poly (vinyl chloride) or a copolymer containing a large proportion of polymerized vinyl chloride.

The microporous material produced by the above process may optionally be stretched. Stretching microporous materials typically results in an increase in the pore volume of the material and the formation of regions with increased or enhanced molecular orientation. As is known in the art, many physical properties of molecularly oriented thermoplastic organic polymers (including tensile strength, tensile modulus, young's modulus, etc.) are quite different from those of corresponding thermoplastic organic polymers with little or no molecular orientation, for example. Stretching is typically accomplished after substantially removing the processing plasticizer as described above.

Various forms of stretching apparatus and methods are known to those skilled in the art and may be used to accomplish the stretching of the microporous materials of the present invention. Stretching of microporous materials is further detailed in U.S. patent No. 5,326,391, column 11, line 45 through column 13, line 13, the disclosure of which is incorporated herein by reference.

The present invention is more particularly described in the following examples, which are intended to be illustrative only, since numerous modifications and variations therein will be apparent to those skilled in the art. All parts and percentages are by weight unless otherwise indicated.

Examples

In section 1 of the following examples, materials and methods for preparing the example mixtures and comparative mixtures prepared in the pilot plant and presented in table 1, and the example mixtures prepared in the scale-up (scale-up) method and the comparative commercial samples presented in table 2 are described. In part 2, a process is described to extrude, calender and extract a sheet prepared from the mixture of part 1 and part 2. In section 3, methods 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. Benzyl acetate test results for the products of tables 1,2, 6, and 8 in section 5 are listed in tables 9, 10, 11, and 12.

Part 1 mixture preparation

The dry ingredients were weighed into an FM-130DLittleford plow blade (ploughblade) mixer with a high intensity chopper type mixing blade in the order and amounts (grams (g)) specified in Table I. The dry ingredients were premixed using only a plow blade for 15 seconds. Then. The process oil (blend oil) is pumped by a hand pump through a spray nozzle at the top of the mixer and only the plow blade is running. The pumping time for this embodiment varies from 45 to 60 seconds. The high intensity shredder knife was activated with the plow blade and the mixture was mixed for 30 seconds. The mixer was turned off and the inside of the mixer was scraped (scraped down) to ensure that all ingredients were mixed evenly. The mixer was again started and both the high intensity chopper and plow blade were started and the mixture was mixed for an additional 30 seconds. The mixer was turned off and the mixture was dumped into a storage vessel.

TABLE 2

Part 2-extrusion, calendering, and extraction

The mixtures of examples 1-9 and comparative examples 1-5 were extruded and calendered into the final sheet form using an extrusion system comprising a feed, extrusion and calendering system as described below. The weight loss of the gravimetric feed system (K-tron model # K2MLT35D5) was used to feed each individual mixture into a 27mm twin screw extruder (model # LeistritzMicro-27 gg). The barrel of the extruder contains eight temperature zones and a heated junction to a sheeting die. The extrusion mixture feed port is located just before the first temperature zone. The vent is located in the third temperature zone. The vacuum hole is located in the seventh temperature zone.

The mixture was fed into the extruder at a rate of 90 g/min. Various amounts of additional process oil are injected as needed in the first temperature zone to achieve extruded sheetThe desired total oil content. The oil contained in the extruded sheet (extrudate) discharged from the extruder is referred to herein as "extrudate oil" or "process oil" and is reported in table 1 in weight percent based on the total weight of the extruded sheet. According to an embodiment of the invention, greater than 0.8g/cm³A dense microporous sheet is obtained when the amount of processing 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 that, from experimental evidence at hand, reducing the amount of processing oil in the extruded microporous sheet increases the density of the microporous sheet, e.g., to greater than 0.8g/cm³And the surface of the sheet is altered so that the volatile material transferred to the vapor-releasing surface is more dispersed and does not initially pool as droplets on that surface.

Discharging the extrudate from the barrel into a sheet 15cm wideA die having a discharge opening of 1.5 mm. The extrusion melt temperature was 203-210 ℃ and the throughput was 7.5 kg/h.

The calendering process is accomplished using a three roll vertical calender stack (stack) having a nip point and a chill roll. Each of the rollers has a chrome surface. The roll dimensions were approximately 41cm length and 14cm diameter. The top roll temperature was maintained between 135 ℃ and 140 ℃. The intermediate roll temperature is maintained between 140 ℃ and 145 ℃. The bottom roll was a chill roll in which the temperature was maintained between l0-21 ℃. The extrudate was calendered into sheet form and passed over a bottom chilled water roll and wound.

Sheet samples cut to widths up to 25.4cm and lengths of 305cm were rolled up and placed in cans and exposed to hot liquid 1,1, 2-trichloroethylene for approximately 7-8 hours to extract oil from the sheet samples. Thereafter, the extracted sheet was air-dried and subjected to the test method described later.

The mixtures of the enlarged examples 10-18 shown in Table 2 were prepared using an extrusion system and an oil extraction method (the above system)Production size version of the system) extruded and calendered into final sheet form, carried out as described in U.S.5,196,262, column 7, line 52 to column 8, line 47, which is incorporated herein by reference. The physical parameters of the final sheet were tested using the test method described above in section 3. Comparative examples 6-10 are commercial microporous products as indicated below: comparative example 6 isDigital10 mils; comparative example 7 isSP6 mil; comparative example 8 isSP10 mil; comparative example 9 isSP14 mil; and comparative example 10 isSP12 mil.

The extrudate oil (% by weight) for the commercial products of comparative examples 6-10 varied from 57 to 62%.

Part 3 test and results

The physical properties measured on the extracted and dried film and the results obtained are listed in tables 3 and 4. The extrudate oil weight percent was measured using a Soxhlet extractor. Extrudate sheet samples that were not extracted beforehand were used to determine the extrudate oil weight percent. A sample specimen of approximately 2.25 inches x5 inches (5.72cmx12.7cm) was weighed and recorded four decimal places. Each sample was then rolled into a cylinder and placed in a Soxhlet extraction apparatus and extracted using Trichloroethylene (TCE) as a solvent for about 30 minutes. The sample was then removed and dried. The extracted and dried sample was then weighed. The oil weight percent values (extrudates) were calculated as follows: oil weight% (starting weight-weight extracted) xl 00/starting weight.

The thickness was determined using an OnOsokki thickness gauge EG-225. Two 4.5 inch x5 inch (11.43cmx12.7cm) samples were cut from each sample and the thickness of each sample was measured at nine locations (at least 3/4 inches (1.91cm) from any edge). The arithmetic mean of the readings is recorded in mils to 2 digits after decimals and converted to microns.

The density of the above examples was determined by dividing the average anhydrous weight of two samples cut from each sample measuring 4.5 inches x5 inches (11.43cmx12.7cm) by the average volume of those samples. The average volume was determined by boiling both samples in deionized water for 10 minutes, removing the two samples and placing in deionized water at room temperature, weighing each sample suspended in deionized water after equilibrating to room temperature, and weighing each sample again in air after wiping off the surface water. The average volume of the samples was calculated as follows:

volume (average) ═ [ (weight of lightly wiped samples weighed in air-sum of the weights of impregnation) x1.002]/2

The anhydrous weight was determined by weighing each of the two samples on an analytical balance and multiplying this weight by 0.98, since the sample was assumed to contain 2% moisture.

The porosity reported in tables 3 and 4 was determined using a Gurley densitometer, model4340, manufactured by gpigurley precision instruments of Troy, new york. The porosity reported is a measure of the rate of air flow through the sample or its resistance to air flow through the sample. The units of measurement are "Gurley seconds" and indicate that water (12.2X 10) is used with a pressure differential of 4.88 inches²Pa) 100cc of air was passed through a 1 inch square (6.4X 10)^-4m²) Time in seconds of area. A lower value equates to less air flow resistance (allowing more air to pass freely). The measurements were performed using the procedures listed in the MODEL4340Automatic densitometer and Smoothness tester Instructions Manual. TAPPI method T460 om-06-AirResistananceof paper is also incorporated by reference as the basic principle for this measurement.

Part 4A-coating formulation and coated product

Coatings 1-5 listed in Table 5 were prepared by mild stirring in a 600 ml beaker325 polyvinyl alcohol in cold water. Gentle stirring was provided by a 1 "(2.54 cm) paddle stirrer driven by an electric stirring motor. The mixture was heated to 190 ° F (87.8 ℃) and stirred for 20-30 minutes. The resulting solution was cooled to room temperature while stirring. The amounts of the specific mixtures and the resulting measured solids are summarized in table 5.

TABLE 5 coating formulations

Coatings confirming no visible undissolved particles were applied to a coating sold by PPGID industries, Pittsburgh, PaHD microporous substrate. The coating was applied to a sheet of 8.5 inch x11 inch (21.59cmx27.94cm), 11 mil thick substrate, each tared on a balance, after which the sheet was placed on a clean glass surface and the top corner of the sheet was adhered to the glass using tape. A piece of clear 10 mil thick polyester 11 inch x3 inch (27.94cm x7.62cm) was placed across the top edge of the sheet, covering 1/2 inches (1.27cm) down from the top edge of the sheet. The polyester was fixed to the glass surface with tape. A wire-wound metering rod from DiversifiedEngineers was placed 1-2 inches (2.5-5.1cm) on the sheet parallel to and near the top edge of the polyester. Using a disposable pipette, a 10-20 ml amount of paint was applied as a beadStrips (stripes) (about% inch (0.64cm) wide) are deposited directly next to and in contact with the metering rod. The bar is attempted to pull completely across the (across) sheet at a continuous/constant rate. The resulting wet sheet was removed from the glass surface, immediately placed on a previous tare balance, weighed, the wet coating weight recorded, and then the coated sheet was placed in a forced air oven and dried at 95 ℃ for 2 minutes. The dried sheet was removed from the oven and the same coating procedure was repeated for the same coated sheet surface. The final dry coat weight (in grams per square meter) was calculated using the wet two coat weight. The coated sheets of examples 19-23 are described in table 6.

TABLE 6 Final coated sheets

The following equation was used to calculate the final dry coating weight.

The calculated final dry coating weight (in grams per square meter) ═ ((coating solids x0.01) x (1 st wet coating weight + 2 nd wet coating weight))/(8.5 xl0.5) x1550

Part 4B coating formulation and coated product

In the paint formulations for making coatings 6-12, the procedure of part 4A was followed, except that coating 7 was mixed for 2 days prior to use. The coating formulations are listed in table 7.

The substrate used in part 4B was sold by PPGIndsuities, Pittsburgh, PaSP1000 microporous substrate. The same procedure was followed for part 4A except that some of the sheets were coated on both sides, the first coated side was dried before the second coated side was applied on the opposite side, and a No. 9 metering rod was used for all coatings. Information on the final coated sheet is included in table 8.

TABLE 7 coating formulations having the amounts listed in grams

(n) WITCOBONDW-240, an aqueous polyurethane dispersion from Chemtura corporation

(0)200, fumed silica from Degussa

(p)T700, precipitated silica from PPG industries, Inc

(q)6200 precipitated silica from PPG industries, Inc

(r) momentive ele-410, an aqueous silicon dispersion from MomentivePerformanceMaterials

(s) HYCAR26138, aqueous poly (meth) acrylate dispersion from Lubrizol advanced materials, Inc

TABLE 8 Final coated sheets

Part 5 benzyl acetate test

The holder set-up for evaporation rate and performance testing of the membranes consisted of a front clamp with an annular gasket, a rear clamp, a test reservoir cup, and four screws. The test reservoir cup is made of a transparent thermoplastic polymer having an inner dimension defined by a circular diameter of about 4cm at the edge of the open face, and a depth of no greater than 1 cm. The open face is used to determine the volatile material transfer rate.

Each clamp of the holder assembly had a circular opening of 1.5 inch (3.8cm) diameter to accommodate the test reservoir cup and to provide an opening to expose the membrane to the test. When the membrane (i.e., a sheet of microporous material having a thickness of 6 to 18 mils) was placed under test, the gripper-assembled back clamp was placed on top of a cork ring (corrring). The test reservoir cup was placed in the back clamp and approximately 2ml of benzyl acetate was charged. A disk of approximately 2 inches (5.1cm) diameter was cut from the film sheet and placed directly on and in contact with the rim of the reservoir cup, resulting in 12.5cm of microporous sheet material²Is 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 without disturbing the membrane disc. When a coated microporous sheet material is used, the coated surface is placed toward the reservoir or toward the atmosphere, as shown in the table below. The screws are attached and locked sufficiently to prevent leakage. The annular gasket creates a seal. The holder is marked to identify the film sample under test. For each test, 5 to 10 replicates were prepared. For the coated examples, five replicates of the control (uncoated samples) were included. For the examples in table 11, there are 5 controls for each example, and the average evaporation rate for each control is reported for the corresponding example, and the percent reduction in evaporation rate for this example compared to the corresponding control is reported. The coated surfaces of examples 19-23 in table 11 were towards the atmosphere.

Each holder assembly was weighed to obtain the starting weight of the entire loaded assembly. This assembly was then placed upright in a laboratory chemical fume hood, 5 feet 1.52 meters](height) x5 feet [1.52 m ]](Width) x2 feet [0.61 m ]]The approximate size of (depth). At least a portion of the benzyl acetate and volatile material contacting surface of the microporous sheet material with the test reservoir uprightAre in direct contact. The glass door of the ventilation hood is pulled down and the air flow through the hood is adjusted so that there is a hood volume of eight (8) revolutions per hour. Unless otherwise indicated, the temperature in the kitchen was maintained at 25 ℃. + -. 5 ℃. The humidity in the fume hood is the ambient temperature. The test reservoir is weighed periodically in this kitchen. The test was performed for five (5) days. The calculated benzyl acetate weight loss was combined with elapsed time and surface area of the microporous sheet exposed to the interior of the test reservoir to determine the volatility transfer rate of the microporous sheet in mg/(hr cm)²). The average evaporation rate (mg/hour) of the replicates is reported in the table below for the entire assembly. These two values are related by the following equation:

average evaporation Rate (mg/hr)/12.5 cm²Volatile material transfer rate (mg/hour cm)²)

Critical (marginal) indicates the presence of duplicates that pass and fail, or testing without failure described as benzyl acetate "pooling" and "dripping" below the surface of the membrane, but with some benzyl acetate droplets forming beads on the membrane surface, which is also considered unacceptable (face-to-face) for being rated as a "pass" result. However, there is a clear performance distinction between Failure (FAIL) test results and critical (Marg.) test results, the latter being clearly superior, as discussed herein.

The data for examples 10-18 and comparative examples 6-10 of tables 2, 4, and 10, which illustrate microporous sheets produced on production scale equipment, confirm the correlation between increasing sheet density (which is achieved by decreasing the amount of extrudate oil in the extruded sheet) and passing benzyl acetate testing. The data are summarized in table 13.

Watch 13

Although specific embodiments of the 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.

Claims

1. A vapor permeable microporous material comprising:

wherein the microporous material has

(1) At least 0.8g/cm³The density of (a) of (b),

(2) a volatile material contacting surface and a vapor-releasing surface, the volatile material contacting surface and the vapor-releasing surface being substantially opposite one another, and

(3) 0.04 to 0.6 mg/(hr cm) when the volatile material contacting surface of the vapor permeable microporous material is placed in contact with a volatile material and the vapor releasing surface is not in direct contact with the volatile material²) The density of the microporous material is such that the vapor release surface is substantially free of liquid volatile material in liquid form when volatile material is transferred from the volatile material contact surface to the vapor release surface.

2. The microporous material of claim 1 wherein said microporous material has a density of from 0.8 to 1.2g/cm³The density of (c).

3. The microporous material of claim 1 wherein said volatile material transfer rate is from 0.30 to 0.55 mg/(hour cm)²)。

4. The microporous material of claim 1 wherein said volatile material transfer rate is from 0.35 to 0.50 mg/(hour cm)²)。

5. The microporous material of claim 1 wherein said volatile material contacting surface and said vapor releasing surface are each free of coating material.

6. The microporous material of claim 1 wherein at least a portion of said volatile material contacting surface has a first coating thereon and/or at least a portion of said vapor releasing surface has a second coating thereon.

7. The microporous material of claim 6 wherein said first coating layer and said second coating layer are each independently formed from an aqueous coating composition selected from the group consisting of aqueous poly (meth) acrylate dispersions, aqueous polyurethane dispersions, aqueous silicone oil dispersions, and combinations thereof.

8. The microporous material of claim 7 wherein the particles of the dispersion of each aqueous coating composition have a particle size of 200 to 400 nm.

9. The microporous material of claim 8 wherein said first coating and said second coating each independently have a weight of from 0.01 to 5.5g/m²Coating weight of (c).

10. The microporous material of claim 1 wherein said polyolefin of the water insoluble thermoplastic organic polymer comprises ultra high molecular weight polyethylene having an intrinsic viscosity of at least 10 deciliters/gram.

11. The microporous material of claim 10 wherein said ultrahigh molecular weight polyolefin is ultrahigh molecular weight polyethylene having an intrinsic viscosity of at least 18 deciliters/gram.

12. The microporous material of claim 11 wherein said ultra high molecular weight polyethylene has an intrinsic viscosity ranging from 18 to 39 deciliters/gram.

13. The microporous material of claim 1 wherein said polyolefin of thermoplastic organic polymer 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 having an astm d1238-86 condition E melt index of less than 50 grams/10 minutes and an astm d1238-86 condition F melt index of at least 0.1 grams/10 minutes.

14. The microporous material of claim 13 wherein said substantially linear ultrahigh molecular weight polyethylene constitutes at least 1% by weight of said matrix and said substantially linear ultrahigh molecular weight polyethylene and said lower molecular weight polyethylene together constitute substantially 100% by weight of the polymer of said matrix.

15. The microporous material of claim 14 wherein said lower molecular weight polyethylene comprises high density polyethylene.

16. The microporous material of claim 1 wherein said particulate filler comprises siliceous particles comprising particulate silica.

17. The microporous material of claim 16 wherein said particulate silica comprises particulate precipitated silica.

18. The microporous material of claim 1 wherein said pores constitute from 35 to 95 volume percent of said microporous material, based on the total volume of said microporous material.

19. A vapor permeable microporous material comprising

wherein the microporous material has

(1) Less than 0.8g/cm³The density of (a) of (b),

(2) a volatile material contacting surface, and a vapor-releasing surface, the volatile material contacting surface and the vapor-releasing surface being substantially opposite one another, and

(3) 0.04 to 0.6 mg/(hr cm) when the volatile material contacting surface of the vapor permeable microporous material is placed in contact with a volatile material and the vapor releasing surface is not in direct contact with the volatile material²) A volatile material transfer rate from the volatile material contacting surface to the vapor releasing surface, and

wherein (i) at least a portion of the volatile material contacting surface has a first coating thereon, and/or (ii) at least a portion of the vapor-releasing surface has a second coating thereon, each of the first coating and the second coating being independently formed from an aqueous coating composition selected from the group consisting of aqueous poly (meth) acrylate dispersions, aqueous polyurethane dispersions, aqueous silicone oil dispersions, and combinations thereof, and the vapor-releasing surface is substantially free of liquid volatile material when volatile material is transferred from the volatile material contacting surface to the vapor-releasing surface.

20. The microporous material of claim 19 wherein said microporous material has a density of 0.4g/cm³To less than 0.8g/cm³The density of (c).

21. The microporous material of claim 19 wherein said microporous material has a density of 0.4g/cm³To 0.7g/cm³The density of (c).

22. The microporous material of claim 19 wherein said volatile material transfer rate is from 0.30 to 0.55 mg/(hour cm)²)。

23. The microporous material of claim 19 wherein the particles of the dispersion of each aqueous coating composition have a particle size of 200 to 400 nm.

24. The microporous material of claim 23 wherein said first coating and said second coatingThe coatings each independently have a weight of 0.1 to 3g/m²Coating weight of (c).

25. The microporous material of claim 19 wherein said polyolefin comprises ultra high molecular weight polyethylene having an intrinsic viscosity of at least 10 deciliters/gram.

26. The microporous material of claim 25 wherein said ultrahigh molecular weight polyolefin is ultrahigh molecular weight polyethylene having an intrinsic viscosity of at least 18 deciliters/gram.

27. The microporous material of claim 26 wherein said ultra high molecular weight polyethylene has an intrinsic viscosity ranging from 18 to 39 deciliters/gram.

28. The microporous material of claim 19 wherein said matrix comprises a mixture of substantially linear ultra high molecular weight polyethylene having an intrinsic viscosity of at least 10 deciliters/gram and lower molecular weight polyethylene having an astm d1238-86 condition E melt index of less than 50 grams/10 minutes and an astm d1238-86 condition F melt index of at least 0.1 grams/10 minutes.

29. The microporous material of claim 28 wherein said substantially linear ultrahigh molecular weight polyethylene constitutes at least 1% by weight of said matrix and said substantially linear ultrahigh molecular weight polyethylene and said lower molecular weight polyethylene together constitute substantially 100% by weight of the polymer of said matrix.

30. The microporous material of claim 29 wherein said lower molecular weight polyethylene is high density polyethylene.

31. The microporous material of claim 19 wherein said particulate filler comprises siliceous particles comprising particulate silica.

32. The microporous material of claim 35 wherein said particulate silica comprises particulate precipitated silica.

33. The microporous material of claim 19 wherein said pores comprise 35 to 95 volume percent of said microporous material based on the total volume of said microporous material.

34. A vapor permeable microporous material comprising:

(a) a substantially water-insoluble thermoplastic organic polymer matrix comprising ultra-high molecular weight polyethylene having an intrinsic viscosity of at least 10 deciliters/gram;

(b) a finely divided substantially water-insoluble particulate silica distributed throughout said matrix and constituting from 40 to 90 weight percent based on the total weight of said microporous material; and

(c) a network of interconnected pores substantially communicating throughout the microporous material, the interconnected pores constituting from 35 to 95 volume percent of the microporous material, based on the total volume of the microporous material;

wherein the microporous material has

(1)0.8 to 1.2g/cm³The density of (a) of (b),

(3) 0.04 to 0.6 mg/(hr cm) when the volatile material contacting surface of the vapor permeable microporous material is placed in contact with a volatile material and the vapor releasing surface is not in direct contact with the volatile material²) The density of the microporous material is such that the vapor release surface is substantially free of volatile material in liquid form when the volatile material is transferred from the volatile material contact surface to the vapor release surface.

35. The vapor permeable microporous material of claim 34 wherein:

(a) the thermoplastic organic polymer comprises a mixture of substantially linear ultra high molecular weight polyethylene having an intrinsic viscosity of at least 10 deciliters/gram and lower molecular weight polyethylene having an astm d1238-86 condition E melt index of less than 50 grams/10 minutes and an astm d1238-86 condition F melt index of at least 0.1 grams/10 minutes;

(b) the particulate filler is precipitated silica; and

(c) the microporous material has a volatile material transfer rate of 0.30 to 0.55 mg/(hr cm)²)。