US4539256A
Expired / Lapsed
US
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Microporous sheet material, method of making and articles made therewith
Assignee: 3M Co
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Filing: 1984-02-28
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Granted: 1985-09-03
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Expires: 2004-02-28
Abstract
Abstract A method of making a microporous material is provided which comprises the steps of melt blending crystallizable thermoplastic polymer with a compound which is miscible with the thermoplastic polymer at the melting temperature of the polymer but phase separates on cooling at or below the crystallization temperature of the polymer, forming a shaped article of the melt blend, cooling the shaped article to a temperature at which the polymer crystallizes to cause phase separation to occur between the thermoplastic polymer and the compound to provide an article comprising a first phase comprising particles of crystallized thermoplastic polymer in a second phase of said compound, orienting the article in at least one direction to provide a network of interconnected micropores throughout. The microporous article comprises about 30 to 80 parts by weight crystallizable thermoplastic polymer and about 70 to 20 parts by weight of the compound. The oriented article has a microporous structure characterized by a multiplicity of spaced randomly dispersed, equiaxed, non-uniform shaped particles of the thermoplastic polymer which are coated with the compound. Adjacent thermoplastic particles within the article are connected to each other by a plurality of fibrils consisting of the thermoplastic polymer. The fibrils radiate in three dimensions from each particle. The compound may be removed from the sheet article. e.g., by solvent extraction. The preferred article is a sheet material.
Inventors
- 👤 Gene H. Shipman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 22:03
CPC Classifications
B; B01; B01D; B01D67/00; B01D67/0002; B01D67/002; B01D71/00; B01D71/06; B29; B29C; B29C55/00; B29C55/005; C; C08; C08J; C08J5/00; C08J5/18; C08J9/00; C08J9/22; C08J9/228; C08J9/28; C08J2201/00; C08J2201/04; C08J2201/054; C08J2201/0542; C08J2201/0543; C08J2201/0545; C08J2201/0546; H; H01; H01M; H01M50/00; H01M50/40; Y; Y02; Y02E; Y02E60/00; Y02E60/10; Y10; Y10T; Y10T428/00; Y10T428/249921; Y10T428/249953; Y10T428/249978; Y10T428/249986; Y10T428/249987; Y10T428/24999
Claims Analysis
Total Claims: 33
Claim 1
Independent Claim
199 words
A method of making a microporous article, comprising: (a) melt blending to form a solution comprising 30 to 80 parts by weight of crystallizable thermoplastic polymer with 70 to 20 parts by weight of a compound with which said thermoplastic polymer is miscible and in which said thermoplastic polymer will dissolve at the melting temperature of said thermoplastic polymer but which will phase separate on cooling to a temperature at or below the crystallization temperature of said thermoplastic polymer; (b) forming a shaped article of the melt blended solution; (c) cooling said shaped article to a temperature at which said thermoplastic polymer crystallizes to cause phase separation to occur between said compound and said polymer thereby to provide an article comprising an aggregate of a first phase comprising particles of crystallized thermoplastic polymer in a second phase comprising said compound with adjacent thermoplastic polymer particles being distinct but having a plurality of zones of continuity; and (d) orienting said article at least in one direction to separate adjacent particles of thermoplastic polymer from one another to provide a network of interconnected micropores therebetween and to permanently attenuate the thermoplastic polymeric material in said zones of continuity to form fibrils.
Claim 2
Independent Claim
199 words
A method of making a microporous article, comprising: (a) melt blending to form a solution comprising 30 to 80 parts by weight of crystallizable thermoplastic polymer with 70 to 20 parts by weight of a compound with which said thermoplastic polymer is miscible and in which said thermoplastic polymer will dissolve at the melting temperature of said thermoplastic polymer but which will phase separate on cooling to a temperature at or below the crystallization temperature of said thermoplastic polymer; (b) forming a shaped article of the melt blended solution; (c) cooling said shaped article to a temperature at which said thermoplastic polymer crystallizes to cause phase separation to occur between said compound and said polymer thereby to provide an article comprising an aggregate of a first phase comprising particles of crystallized thermoplastic polymer in a second phase comprising said compound with adjacent thermoplastic polymer particles being distinct but having a plurality of zones of continuity; and (d) orienting said article at least in one direction to separate adjacent particles of thermoplastic polymer from one another to provide a network of interconnected micropores therebetween and to permanently attenuate the thermoplastic polymeric material in said zones of continuity to form fibrils.
Claim 3
Dependent Claim
54 words
The method of claim 1 wherein said melt blend solution is formed at a temperature in a range from approximately 50° C. below the equilibrium melting point of said pure thermoplastic polymer to a temperature above the equilibrium melting point but below the thermal degradation temperature of said thermoplastic polymer and of said compound.
Claim 4
Dependent Claim
18 words
The method of claim 1 wherein said cooling comprises immersing said shaped article into a liquid cooling medium.
Claim 5
Dependent Claim
17 words
The method of claim 1 wherein said cooling comprises casting said shaped article onto a casting wheel.
Claim 6
Dependent Claim
11 words
The method of claim 1 wherein said orienting is biaxial orienting.
Claim 7
Dependent Claim
30 words
The method of claim 1 wherein said orienting provides a length increase in said article of from about 10 to about 1,000 percent of the original length of said article.
Claim 8
Dependent Claim
13 words
The method of claim 1 comprising the additional step of removing said compound.
Claim 9
Dependent Claim
17 words
The method of claim 7 wherein said compound is solvent-soluble and said removing is by solvent extraction.
Claim 10
Dependent Claim
19 words
The method of claim 7 wherein said compound is volatile and said removing is by volatilization of said compound.
Claim 11
Dependent Claim
28 words
The method of claim 1 comprising the additional step of dimensionally stabilizing said article by heating the oriented article, while it is restrained, to a heat stabilizing temperature.
Claim 12
Independent Claim
22 words
The method of claims 1, 5, 6 or 10 comprising the additional step of laminating said microporous article to a second article.
Claim 13
Dependent Claim
69 words
The method of claim 1 wherein said thermoplastic polymer and said compound are selected from the group consisting of (a) polypropylene with mineral oil, dioctylphthalate or mineral spirits; (b) polyethylene with mineral oil or mineral spirits; (c) polypropylene-polyethylene copolymer with mineral oil; (d) polyethylene terephthalate with diethylphthalate; (e) polycaprolactam with triethylene glycol; (f) polyvinylidene fluoride with dibutyl phthalate; (g) polybutylene terephthalate with diethylphthalate; and (h) polyester copolymer with dioctylphthalate.
Claim 14
Dependent Claim
21 words
The method of claim 1 wherein said crystallizable thermoplastic polymer has a tensile strength of at least 70 kg/cm 2 .
Claim 15
Dependent Claim
137 words
A microporous material comprising about 30 to 80 parts by weight of crystallizable thermoplastic polymer and about 70 to 20 parts by weight of a compound with which said thermoplastic polymer is miscible and in which said thermoplastic polymer will dissolve at the melting temperature of said thermoplastic polymer but will phase separate on cooling to a temperature at or below the crystallization temperature of said thermoplastic polymer, said microporous material having an internal structure characterized by a multiplicity of spaced, randomly dispersed, non-uniform shaped, equiaxed particles of said thermoplastic polymer coated with said compound, adjacent coated particles throughout said material being separated from one another to provide said material with a network of interconnected micropores and said adjacent thermoplastic polymer particles being connected to each other by a plurality of fibrils consisting of said thermoplastic polymer.
Claim 16
Dependent Claim
137 words
A microporous material comprising about 30 to 80 parts by weight of crystallizable thermoplastic polymer and about 70 to 20 parts by weight of a compound with which said thermoplastic polymer is miscible and in which said thermoplastic polymer will dissolve at the melting temperature of said thermoplastic polymer but will phase separate on cooling to a temperature at or below the crystallization temperature of said thermoplastic polymer, said microporous material having an internal structure characterized by a multiplicity of spaced, randomly dispersed, non-uniform shaped, equiaxed particles of said thermoplastic polymer coated with said compound, adjacent coated particles throughout said material being separated from one another to provide said material with a network of interconnected micropores and said adjacent thermoplastic polymer particles being connected to each other by a plurality of fibrils consisting of said thermoplastic polymer.
Claim 17
Dependent Claim
22 words
The material of claim 14 in which the crystallizable thermoplastic polymer has a tensile strength of at least 70 kg/cm 2 .
Claim 18
Dependent Claim
16 words
A laminated structure comprising the microporous material of claim 14 and at least one other material.
Claim 19
Dependent Claim
70 words
The microporous material of claim 14 wherein said thermoplastic polymer and said compound are selected from the group consisting of (a) polypropylene with mineral oil, dioctylphthalate or mineral spirits; (b) polyethylene with mineral oil or mineral spirits; (c) polypropylene-polyethylene copolymer with mineral oil; (d) polyethylene terephthalate with diethylphthalate; (e) polycaprolactam with triethylene glycol; (f) polyvinylidene fluoride with dibutyl phthalate; (g) polybutylene terephthalate with diethylphthalate; and (h) polyester copolymer with dioctylphthalate.
Claim 20
Dependent Claim
66 words
A microporous material comprising crystallizable thermoplastic polymer, said microporous material having an internal structure characterized by a multiplicity of spaced, randomly disposed, non-uniform shaped, equiaxed particles of said thermoplastic polymer, adjacent particles throughout said material being separated from one another to provide said material with a network of interconnected micropores and being connected to each other by a plurality of fibrils consisting of said thermoplastic polymer.
Claim 21
Dependent Claim
66 words
A microporous material comprising crystallizable thermoplastic polymer, said microporous material having an internal structure characterized by a multiplicity of spaced, randomly disposed, non-uniform shaped, equiaxed particles of said thermoplastic polymer, adjacent particles throughout said material being separated from one another to provide said material with a network of interconnected micropores and being connected to each other by a plurality of fibrils consisting of said thermoplastic polymer.
Claim 22
Dependent Claim
16 words
A laminated structure comprising the microporous material of claim 18 and at least one other material.
Claim 23
Independent Claim
20 words
The method of claims 1 or 7 comprising the additional step of imbibing the microporous material with an imbibing material.
Claim 24
Independent Claim
17 words
The method of claims 1 or 7 comprising the additional step of coating the resultant microporous material.
Claim 25
Dependent Claim
19 words
The microporous material of claims 14 and 18 containing an additional substance which at least partially fills said micropores.
Claim 26
Dependent Claim
13 words
The microporous material of claims 14 or 18 coated with a coating material.
Claim 27
Dependent Claim
15 words
The coated microporous material of claim 23 wherein said coating material is vapor deposited metal.
Claim 28
Dependent Claim
11 words
The method of claim 1 wherein said thermoplastic polymer is polyethylene.
Claim 29
Dependent Claim
14 words
The microporous material of claims 14 or 18 wherein said thermoplastic material is polyethylene.
Claim 30
Dependent Claim
11 words
The method of claim 1 wherein said article is a sheet.
Claim 31
Dependent Claim
14 words
The microporous material of claims 14 or 18 in the shape of a sheet.
Claim 32
Dependent Claim
80 words
A sheet material having a microporous structure extending to one major surface characterized by a multiplicity of spaced, randomly disposed, non-uniform shaped, equiaxed particles of thermoplastic polymer, adjacent particles throughout said microporous structure being separated from one another to provide said microporous structure with a network of interconnected micropores and being connected to each other by a plurality of fibrils consisting of said thermoplastic polymer and an opposite major surface comprised of said polymer but not having said microporous structure.
Claim 33
Dependent Claim
80 words
A sheet material having a microporous structure extending to one major surface characterized by a multiplicity of spaced, randomly disposed, non-uniform shaped, equiaxed particles of thermoplastic polymer, adjacent particles throughout said microporous structure being separated from one another to provide said microporous structure with a network of interconnected micropores and being connected to each other by a plurality of fibrils consisting of said thermoplastic polymer and an opposite major surface comprised of said polymer but not having said microporous structure.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-09-02 | 1989-03-04 | 1989-09-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-09-02 | 1993-03-04 | 1993-09-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-09-02 | 1997-03-04 | 1997-09-03 | $7700.00 | Window Closed / Lapsed |