Microporous polymeric films and process for their manufacture

Claim 2

A microporous, tear resistant film substantially free of cracks detectable with an electron microscope and having a water vapor permeability of at least ##EQU3## according to ASTM 96-66BW (inverted cup method) and possessing hydrostatic resistance to the penetration of liquid water of at least 0.25 kPa, said film being made by a process comprising a stretching at a temperature no higher than about 10° C. above the Vicat softening point but at least 10° C. above the glass transition temperature of the matrix polymer a precursor film having at most very low porosity and consisting essentially of the following components: (a) a matrix of a thermoplastic orientable polymer characterized by (1) a hydrophobic surface, as indicated by a contact angle between said surface and a droplet of water of at least about 40°; (2) a glass transition temperature, Tg, of less than about 25° C.; (3) a Vicat softening point, Tv, of more than about 25° C.; (4) ultimate elongation at some temperature between Tg and Tv of at least 100%; and (5) a flexural modulus at 25° C. of less than about 200 MPa; said thermoplastic orientable matrix polymer being a polymer selected from the group consisting of ethylene copolymers and copolyesters; (b) about 20-40%, based on the volume of the final composition, of a particulate filler chemically nonreactive with the polymer matrix and dispersed therein by melt-blending, said filler being characterized by (1) a sufficiently high softening temperature to avoid particle distortion at the lowest temperature at which the matrix polymer is sufficiently fluid to be satisfactorily melt-blended; (2) an aspect ratio of less than about 3; (3) an average equivalent spherical diameter of about 0.05-50 μm; (4) an at most negligible electrostatic or dipole attraction to the matrix polymer; and (5) a surface tension which either has at the lowest temperature at which the matrix polymer is sufficiently fluid to be satisfactorily melt-blended a value at most about equal to that of the matrix polymer of can be corrected to have under the blending conditions at most such a value by the adsorption on its surface of a third component (c); said component (c) being an organic compound, which is liquid at the lowest temperatue at which the matrix polymer is sufficiently fluid to be melt-blended and is capable at that temperature of being adsorbed on the surface of filler (b) to the extent of at least about 0.5×10 -5 mole of component (c) per square meter of surface area of filler (b), as calculated from the average equivalent spherical diameter of filler (b), and being present in the blend in an amount at least sufficient to satisfy this requirement; said component (c) being characterized by (1) at most negligible solubility in the matrix polymer at the melt-blending temperature; (2) chemical inertness to the matrix polymer; (3) a number average moelcular weight of about 100-10,000; and (4) a surface tension which at the temperature at which component (c) is liquid has a value at most about equal to that of the matrix polymer; and recovering the resulting microporous film.

Claim 3

A microporous film of claim 1 wherein the matrix polymer has a flexural modulus of less than about 100 MPa.

Claim 4

A film of claim 1 wherein the ultimate elongation of the amtrix polymer at a temperature comprised between the polymer's glass transition temperature and its Vicat softening point is at least about, 500%.

Claim 5

A film of claim 3 wherein the ultimate elongation of the matrix polymer, at least 700%.

Claim 6

A film of claim 1 wherein the polymer is selected from ethylene copolymers with at least one comonomer selected from the group consisting of vinyl esters of saturated C 1 -C 4 carboxylic acids; unsaturated C 3 -C 5 mono- or dicarboxylic acids, their salts with ammonia and with metals of Groups I-IV of the Periodic Chart of the Elements, and their C 1 -C 8 alkyl esters; terpolymers of the general formula E/X/Y, where E stands for ethylene, X for vinyl acetate or a butyl acrylate, and Y for carbon monoxide or sulfur dioxide, the weight proportion of comonomer Y being up to about 15%; and elastomeric dipolymers and terpolymers of ethylene with other 1-olefins and 1,4-dienes.

Claim 7

A film of claim 1 wherein the polymer is a copolymer of phthalic acid with 1,4-butanediol and poly(tetramethyleneether glycol).

Claim 8

A film of claim 1 wherein the matrix polymer is a blend of two or more polymers, which individually may not satisfy all the critical requirements recited for the polymer material, provided the blend satisfies those requirements.

Claim 9

A film of claim 7 wherein the matrix polymer is a polymer blend selected from blends of two different ethylene/vinyl acetate copolymers and blends of polyvinyl chloride with an ethylene/vinyl acetate/carbon monoxide terpolymer.

Claim 10

A film of claim 1 wherein the composition from which film is made contains a plasticizer soluble in the polymer matrix.

Claim 11

A film of claim 1 wherein the average equivalent spherical diameter of the filler is about 0.10 to 5 μm.

Claim 12

A film of claim 1 in which the particle size distribution is such that fewer than about 1% of the particles exceed an average equivalent spherical diameter of about 20 μm.

Claim 13

A film of claim 11 in which the particle size distribution is such that fewer than about 1% exceed about 10 μm.

Claim 14

A film of claim 11 in which the amount of filler in the composition is about 25-35 volume percent.

Claim 15

A film of claim 1 wherein the composition from which film is made also contains an antagonizer, which satisfies the requirements of component (c) of claim 1.

Claim 16

A film of claim 14 wherein the surface contact angle of the antagonizer on the surface of the polymer is less than about 40°; the antagonizer is nonfugitive during compounding, and is a low-viscosity liquid at the compounding temperature.

Claim 17

A film of claim 15 wherein the rate of streching of film is about 1-100% per second.

Claim 18

A film of claim 16 wherein the film is stretched biaxially to an extent of at least 50% in each direction.

Claim 19

A film of claim 16 wherein the film is uniaxially streched at least 125%.

Claim 20

The film of claim 1, wherein the matrix polymer is an ethylene/vinyl acetate copolymer, and the filler is calcium carbonate.

Claim 21

The film of claim 21, wherein the matrix polymer is an ethylene/vinyl acetate copolymer, and the filler is calcium carbonate.

Claim 22

A soft, tear resistant, microporous film substatially free of cracks detectable with an electron microscope and consisting essentially of a polymer matrix and a particulate filler material dispersed therein, said film having a water vapor permeability of at least ##EQU4## according to ASTM 96-66BW (inverted cup method) and possessing hydrostatic resistance to the penetration of liquid water of at least 0.25 kPa, the film composition consisting essentially of the following components: (a) a matrix of a thermoplastic orientable polymer characterized by (1) a hydrophobic surface, as indicated by a contact angle between said surface and a droplet of water of at least about 40°; (2) a glass transition temperature, Tg, of less than about 25° C.; (3) a Vicat softening point, Tv, of more than about 25° C.; (4) ultimate elongation at some temperature between Tg and Tv of at least 100%; and (5) a flexural modulus at 25° C. of less than about 200 MPa; said thermoplastic orientable matrix polymer being a polymer selected from the group consisting of copolymers of ethylene and copolyesters; (b) about 20-40%, based on the volume of the final composition, of a particulate filler chemically nonreactive with the polymer matrix and dispersed therein, said filler being characterized by (1) a softening point sufficiently high to avoid particle distortion at the lowest temperature at which the matrix polyer has sufficient fluidity to be satisfactorily melt-blended; (2) an aspect ratio of less than about 3; (3) an average equivalent spherical diameter of about 0.05-50 μm; (4) an at most negligible electrostatic or dipole attraction to the matrix polymer; and (5) a surface tension which either has at the lowest temperature at which the matrix polymer is sufficiently fluid to be satisfactorily melt-blended a value at most about equal to that or the matrix polymer or can be corrected to have at that temperature at most such a value by the adsorption on its surface of a third component (c); said component (c) being an organic compound, which is liquid at the lowest temperature at which the matrix polymer is sufficiently fluid to be melt-blended and is capable at that temperature of being adsorbed on the surface of filler (b) to the extent of at least about 0.5×10 -5 mole of component (c) per square meter of surface area of filler (b), as calculated from the average equivalent spherical diameter of filler (b), and being present in the blend in an amount at least sufficient to satisfy this requirement; said component (c) being characterized by (1) at most neglible solubility in the matrix polymer at the melting temperature of the matrix polymer; (2) chemical inertness to the matrix polymer; (3) a number average molecular weight of about 100-10,000; and (4) a surface tension which at the temperature at which component (c) is liquid has a value at most about equal to that of the matrix polymer.

Claim 23

A soft, tear resistant, microporous film substatially free of cracks detectable with an electron microscope and consisting essentially of a polymer matrix and a particulate filler material dispersed therein, said film having a water vapor permeability of at least ##EQU4## according to ASTM 96-66BW (inverted cup method) and possessing hydrostatic resistance to the penetration of liquid water of at least 0.25 kPa, the film composition consisting essentially of the following components: (a) a matrix of a thermoplastic orientable polymer characterized by (1) a hydrophobic surface, as indicated by a contact angle between said surface and a droplet of water of at least about 40°; (2) a glass transition temperature, Tg, of less than about 25° C.; (3) a Vicat softening point, Tv, of more than about 25° C.; (4) ultimate elongation at some temperature between Tg and Tv of at least 100%; and (5) a flexural modulus at 25° C. of less than about 200 MPa; said thermoplastic orientable matrix polymer being a polymer selected from the group consisting of copolymers of ethylene and copolyesters; (b) about 20-40%, based on the volume of the final composition, of a particulate filler chemically nonreactive with the polymer matrix and dispersed therein, said filler being characterized by (1) a softening point sufficiently high to avoid particle distortion at the lowest temperature at which the matrix polyer has sufficient fluidity to be satisfactorily melt-blended; (2) an aspect ratio of less than about 3; (3) an average equivalent spherical diameter of about 0.05-50 μm; (4) an at most negligible electrostatic or dipole attraction to the matrix polymer; and (5) a surface tension which either has at the lowest temperature at which the matrix polymer is sufficiently fluid to be satisfactorily melt-blended a value at most about equal to that or the matrix polymer or can be corrected to have at that temperature at most such a value by the adsorption on its surface of a third component (c); said component (c) being an organic compound, which is liquid at the lowest temperature at which the matrix polymer is sufficiently fluid to be melt-blended and is capable at that temperature of being adsorbed on the surface of filler (b) to the extent of at least about 0.5×10 -5 mole of component (c) per square meter of surface area of filler (b), as calculated from the average equivalent spherical diameter of filler (b), and being present in the blend in an amount at least sufficient to satisfy this requirement; said component (c) being characterized by (1) at most neglible solubility in the matrix polymer at the melting temperature of the matrix polymer; (2) chemical inertness to the matrix polymer; (3) a number average molecular weight of about 100-10,000; and (4) a surface tension which at the temperature at which component (c) is liquid has a value at most about equal to that of the matrix polymer.

Claim 24

A film of claim 21 wherein the matrix polymer has a flexural modulus of less than about 100 MPa.

Claim 25

A film of claim 21 wherein the Vicat softening point of the matrix polymer is above about 45° C.

Claim 26

A film of claim 21 wherein the ultimate elongation of the matrix polymer at a temperature comprised between the polymer's glass transition temperature and its Vicat softening point is at least about 500%.

Claim 27

A film of claim 24 wherein the ultimate elongation of the matrix polymer at least 700%.

Claim 28

A film of claim 21 wherein the polymer is selected from ethylene copolymers with at least one comonomer selected from the group consisting of vinyl esters of saturated C 1 -C 4 carboxylic acids; unsaturated C 3 -C 5 mono- or dicarboxylic acids, their salts with ammonia and with metals of Groups I-IV of the Periodic Chart of the Elements, and their C 1 -C 8 alkyl esters; terpolymers of the general formula E/X/Y, where E stands for ethylene, X for vinyl acetate or a butyl acrylate, and Y for carbon monoxide or sulfur dioxide, the weight proportion of comonomer Y being up to about 15%; and elastomeric dipolymers and terpolymers of ethylene with other 1-olefins and 1,4-dienes.

Claim 29

A film of claim 21 wherein the polymer is a copolymer of phthalic acid with 1,4-butanediol and poly(tetramethyleneether glycol).

Claim 30

A film of claim 21 wherein the matrix polymer is a blend of two or more polymers, which individually may not satisfy all the critical requirements recited for the polymer material, provided the blend satisfies those requirements.

Claim 31

A film of claim 28 wherein the matrix polymer is a polymer blend selected from blends of two different ethylene/vinyl acetate copolymers and blends of polyvinyl chloride with an ethylene/vinyl acetate/carbon monoxide terpolymer.

Claim 32

A film of claim 21 wherein the composition from which film is made contains a plasticizer soluble in the polymer matrix.

Claim 33

A film of claim 21 wherein the average equivalent spherical diameter of the filler is about 0.10 to 5 μm.

Claim 34

A film of claim 21 in which the particle size distribution is such that fewer than about 1% of the particles exceed an average equivalent spherical diameter of about 20 μm.

Claim 35

A film of claim 32 in which the particle size distribution is such that fewer than about 1% exceed about 10 μm.

Claim 36

A film of claim 21 in which the amount of filler in the composition is about 25-35 volume percent.

Claim 37

A film of claim 21 wherein the composition from which the film is made also contains an antagonizer, which satisfies the requirements of component (c) in claim 21.

Claim 38

A film of claim 35 wherein the surface contact angle of the antagonizer on the surface of the polymer is less than about 40°; the antagonizer is nonfugitive during compounding, and is a low-viscosity liquid at the compounding temperature.

Claim 39

A film of claim 36 which is stretched biaxially to an extent of at least 50% in each direction.

Claim 40

A film of claim 36 which is stretched uniaxially to an extent of at least 125%.

Claim 41

A process for making a soft, tear resistant, microporous film consisting essentially of a polymer matrix and a particulate filler material dispersed therein, said film being substantially free of cracks detectable with an electron microscope and having a water vapor permeability of at least ##EQU5## according to ASTM 96-66BW (inverted cup method) and possessing hydrostatic resistance to the penetration of liquid water of at least 0.25 kPa, said process comprising stretching at a temperature no higher than about 10° C. above the Vicat softening point but at least 10° C. above the glass transition temperature of the matrix polymer a precursor film at most very low porosity and consisting essentially of the following components: (a) a matrix of a thermoplastic orientable polymer characterized by (1) a hydrophobic surface, as indicated by a contact angle between said surface and a droplet of water of at least about 40°; (2) a glass transition temperature, Tg, of less than about 25° C.; (3) a Vicat softening point, Tv, of more than about 25° C.; (4) ultimate elongation at some temperature between Tg and Tv of at least 100%; and (5) a flexural modulus at 25° C. of less than about 200 MPa; said thermoplastic orientable matrix polymer being a polymer selected from the group consisting of ethylene copolymers and copolyesters; (b) about 20-40%, based on the volume of the final composition, of a particulate filler chemically nonreactive with the polymer matrix and dispersed therein by melt-blending, said filler being characterized by (1) a sufficiently high softening temperature to avoid particle distortion at the lowest temperature at which the matrix polymer is sufficiently fluid to be satisfactorily melt-blended; (2) an aspect ratio of less than about 3; (3) an average equivalent spherical diameter of about 0.05-50 μm; (4) an at most negligible electrostatic or dipole attraction to the matrix polymer; and (5) a surface tension which either has at the lowest temperature at which the matrix polymer is sufficiently fluid to be satisfactorily melt-blended a value at most about equal to that of the matrix polymer or can be corrected to have under the blending conditions at most such a value by the adsorption on its surface of a third component (c); said component (c) being an organic compound, which is liquid at the lowest temperature at which the matrix polymer is sufficiently fluid to be satisfactorily melt-blended and is capable at that temperature of being adsorbed on the surface of filler (b) to the extent of at least about 0.5×10 -5 mole of component (c) per square meter of surface area of filler (b), as calculated from the average equivalent spherical diameter of filler (b), and being present in the blend in an amount at least sufficient to satisfy this requirement; said component (c) being characterized by (1) at most negligible solubility in the matrix polymer at the melt-blending temperature; (2) chemical inertness to the matrix polymer; (3) a number average molecular weight of about 100-10,000; and (4) a surface tension which at the temperature at which component (c) is liquid has a value at most about equal to that of the matrix polymer; and recovering the resulting microporous film.

Claim 42

A process for making a soft, tear resistant, microporous film consisting essentially of a polymer matrix and a particulate filler material dispersed therein, said film being substantially free of cracks detectable with an electron microscope and having a water vapor permeability of at least ##EQU5## according to ASTM 96-66BW (inverted cup method) and possessing hydrostatic resistance to the penetration of liquid water of at least 0.25 kPa, said process comprising stretching at a temperature no higher than about 10° C. above the Vicat softening point but at least 10° C. above the glass transition temperature of the matrix polymer a precursor film at most very low porosity and consisting essentially of the following components: (a) a matrix of a thermoplastic orientable polymer characterized by (1) a hydrophobic surface, as indicated by a contact angle between said surface and a droplet of water of at least about 40°; (2) a glass transition temperature, Tg, of less than about 25° C.; (3) a Vicat softening point, Tv, of more than about 25° C.; (4) ultimate elongation at some temperature between Tg and Tv of at least 100%; and (5) a flexural modulus at 25° C. of less than about 200 MPa; said thermoplastic orientable matrix polymer being a polymer selected from the group consisting of ethylene copolymers and copolyesters; (b) about 20-40%, based on the volume of the final composition, of a particulate filler chemically nonreactive with the polymer matrix and dispersed therein by melt-blending, said filler being characterized by (1) a sufficiently high softening temperature to avoid particle distortion at the lowest temperature at which the matrix polymer is sufficiently fluid to be satisfactorily melt-blended; (2) an aspect ratio of less than about 3; (3) an average equivalent spherical diameter of about 0.05-50 μm; (4) an at most negligible electrostatic or dipole attraction to the matrix polymer; and (5) a surface tension which either has at the lowest temperature at which the matrix polymer is sufficiently fluid to be satisfactorily melt-blended a value at most about equal to that of the matrix polymer or can be corrected to have under the blending conditions at most such a value by the adsorption on its surface of a third component (c); said component (c) being an organic compound, which is liquid at the lowest temperature at which the matrix polymer is sufficiently fluid to be satisfactorily melt-blended and is capable at that temperature of being adsorbed on the surface of filler (b) to the extent of at least about 0.5×10 -5 mole of component (c) per square meter of surface area of filler (b), as calculated from the average equivalent spherical diameter of filler (b), and being present in the blend in an amount at least sufficient to satisfy this requirement; said component (c) being characterized by (1) at most negligible solubility in the matrix polymer at the melt-blending temperature; (2) chemical inertness to the matrix polymer; (3) a number average molecular weight of about 100-10,000; and (4) a surface tension which at the temperature at which component (c) is liquid has a value at most about equal to that of the matrix polymer; and recovering the resulting microporous film.

Claim 43

Process of claim 39 wherein the matrix polymer has a flexural modulus of less than about 100 MPa.

Claim 44

Process of claim 40 wherein the Vicat softening point of the matrix polymer is above about 45° C.

Claim 45

Process of claim 39 wherein the ultimate elongation of the matrix polymer at a temperature comprised between the polymer's glass transition temperature and its Vicat softening point is at least about 500%.

Claim 46

Process of claim 42 wherein the ultimate elongation of the matrix polymer is at least 700%.

Claim 47

Process of claim 39 wherein the polymer is selected from ethylene copolymers with at least one comonomer selected from the group consisting of vinyl esters of saturated C 1 -C 4 carboxylic acids; unsaturated C 3 -C 5 mono- or dicarboxylic acids, their salts with ammonia and with metals of Groups I-IV of the Periodic Chart of the Elements, and their C 1 -C 8 alkyl esters; terpolymers of the general formula E/X/Y, where E stands for ethylene, X for vinyl acetate or a butyl acrylate, and Y for carbon monoxide or sulfur dioxide, the weight proportion of comonomer Y being up to about 15%; and elastomeric dipolymers and terpolymers of ethylene with other 1-olefins and 1,4-dienes.

Claim 48

Process of claim 39 wherein the polymer is a copolymer of phthalic acid with 1,4-butanediol and poly(tetramethyleneether glycol).

Claim 49

Process of claim 39 wherein the matrix polymer is a blend of two or more polymers, which individually may not satisfy all the critical requirements recited for the polymer material, provided the blend satisfies those requirements.

Claim 50

Process of claim 46 wherein the matrix polymer is a polymer blend selected from blends of two different ethylene/vinyl acetate copolymers and blends of polyvinyl chloride with an ethylene/vinyl acetate/carbon monoxide terpolymer.

Claim 51

Process of claim 39 wherein the composition from which film is made contains a plasticizer soluble in the polymer matrix.

Claim 52

Process of claim 39 wherein the average equivalent spherical diameter of the filler is about 0.10 to 5 μm.

Claim 53

Process of claim 39 in which the particle size distribution is such that fewer than about 1% of the particles exceed an average equivalent spherical diameter of about 20 μm.

Claim 54

Process of claim 50 in which the particle size distribution is such that fewer than about 1% exceed about 10 μm.

Claim 55

Process of claim 50 in which the amount of filler in the composition is about 25-35 volume percent.

Claim 56

Process of claim 39 wherein the composition from which film is made also contains an antagonizer, which satisfies the requirements of component (c) of claim 1.

Claim 57

A process of claim 53 wherein the surface contact angle of the antagonizer on the surface of the polymer is less than about 40°; the antagonizer is nonfugitive during compounding, and is a low-viscosity liquid at the compounding temperature.

Claim 58

Process of claim 54 wherein the rate of stretching of film is about 1-100% per second.

Claim 59

Process of claim 55 wherein the film is stretched biaxially to an extent of at least 50% in each direction.

Claim 60

Process of claim 55 wherein the film is stretched uniaxially at least 125%.

Claim 61

The process of claim 39 wherein the matrix polymer is an ethylene/vinyl acetate copolymer, and the filler is calcium carbonate.