EP0105629A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Microporous sheet material, method of making and articles made therewith
Assignee: 3M Co
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Filing: 1983-09-06
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Granted: —
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Expires: 2003-09-06
Abstract
Abstract A method of making a microporous sheet is provided which comprises the steps of melt blending crystallizable thermoplastic polymer with a compound which is miscible with the thermoplastic polymer at the polymer melting temperature but immiscible on cooling below the polymer melting temperature, forming a sheet of the melt blend, cooling the sheet to a temperature at which the compound becomes immiscible with the polymer to cause phase separation to occur between the thermoplastic polymer and the compound to provide a sheet comprising a first phase comprising particles of thermoplastic polymer in a second phase of said compound, orienting the film in at least one direction to provide a network of interconnected micropores throughout the sheet. The microporous sheet comprises about 30 to 80 parts by weight crystallizable thermoplastic polymer and correspondingly about 70 to 20 pans by weight of the compound. The oriented sheet has a microporous structure characterized by a multiplicity of spaced randomly dispersed, equiaxed, non-uniform shaped, non-porous particles of the thermoplastic polymer which are coated with the compound. Adjacent thermoplastic particles within the sheet 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. e.g., by solvent extraction.
Inventors
- 👤 Gene H. C/O Minnesota Mining And Shipman
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-23 19:15
CPC Classifications
B; B01; B01D; B01D67/00; B01D67/0002; B01D67/0023; B01D67/0025; B01D67/0027; C; C08; C08J; C08J5/00; C08J5/18; H; H01; H01M; H01M50/00; H01M50/40; H01M50/489; H01M50/491; B29; B29C; B29C55/00; B29C55/005; C08J9/00; C08J9/22; C08J9/228; C08J9/28; B01D2323/00; B01D2323/12; C08J2201/00; C08J2201/04; C08J2201/054; C08J2201/0542; C08J2201/0543; C08J2201/0545; C08J2201/0546; Y; Y02; Y02E; Y02E60/00; Y02E60/10
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
222 words
A method of making a microporous sheet, characterized by including the following steps: (a) melt blending to form a solution of 30 to 80 parts by weight of a crystallizable thermoplastic polymer with correspondingly 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 is immiscible below the melting temperature of said thermoplastic polymer and from which said thermoplastic polymer will phase separate on cooling to a temperature below the melting temperature of said thermoplastic polymer; (b) forming a sheet of the melt blended solution; (c) cooling said sheet to a temperature at which said compound becomes immiscible with said thermoplastic polymer to cause phase separation to occur between said compound and said polymer thereby to provide a sheet comprising an aggregate of a first phase comprising particles of said 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 sheet 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
222 words
A method of making a microporous sheet, characterized by including the following steps: (a) melt blending to form a solution of 30 to 80 parts by weight of a crystallizable thermoplastic polymer with correspondingly 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 is immiscible below the melting temperature of said thermoplastic polymer and from which said thermoplastic polymer will phase separate on cooling to a temperature below the melting temperature of said thermoplastic polymer; (b) forming a sheet of the melt blended solution; (c) cooling said sheet to a temperature at which said compound becomes immiscible with said thermoplastic polymer to cause phase separation to occur between said compound and said polymer thereby to provide a sheet comprising an aggregate of a first phase comprising particles of said 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 sheet 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
13 words
The method of claim 1 further characterized by said orienting being biaxial orienting.
Claim 4
Dependent Claim
32 words
The method of claim 1 further characterized by said orienting providing a length increase in said sheet of from about 10 to about 1,000 percent of the original length of said sheet.
Claim 5
Dependent Claim
16 words
The method of claim 1 further characterized by including the additional step of removing said compound.
Claim 6
Dependent Claim
31 words
The method of claim 1 further characterized by including the additional step of dimensionally stabilizing said sheet by heating the oriented sheet, while it is restrained, to a heat stabilizing temperature.
Claim 7
Independent Claim
25 words
The method of claims 1, 3, 4 and 5 further characterized by including the additional step of laminating said microporous sheet to a second sheet.
Claim 8
Dependent Claim
71 words
The method of claim 1 further characterized by said thermoplastic polymer and said compound being 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 9
Dependent Claim
165 words
A microporous sheet material made according to the process of claim 1 characterized by comprising about 30 to 80 parts by weight of crystallizable thermoplastic polymer and correspondingly 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 with which said thermoplastic polymer is immiscible below said melting temperature and from which said thermoplastic polymer will phase separate on cooling to a temperature below said melting temperature of said thermoplastic polymer, said microporous sheet having an internal structure characterized by a multiplicity of spaced, randomly dispersed; non-uniform shaped, equiaxed, non-porous particles of said thermoplastic polymer coated with said compound, adjacent coated particles throughout said sheet being separated from one another to provide said sheet 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 10
Dependent Claim
21 words
A laminated structure further characterized by including the microporous sheet material of claim 8 and at least one other sheet material.
Claim 11
Dependent Claim
73 words
The microporous sheet material of claim 8 further characterized by said thermoplastic polymer and said compound being 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 12
Dependent Claim
78 words
A microporous sheet material made according to the process of claim 5 characterized by comprising crystallizable thermoplastic polymer, said microporous sheet having an internal structure characterized by a multiplicity of spaced, randomly disposed, non-uniform shaped, equiaxed, non-porous particles of said thermoplastic polymer, adjacent particles throughout said sheet being separated from one another to provide said sheet with a network of interconnected micropores and being connected to each other by a plurality of fibrils consisting of said thermoplastic polymer.
Claim 13
Dependent Claim
20 words
A laminated structure further characterized by including the microporous sheet of claim 18 and at least one other sheet material.
Claim 14
Independent Claim
24 words
The method of claims 1 and 4 further characterized by including the additional step of imbibing the microporous sheet material with an imbibing material.
Claim 15
Independent Claim
21 words
The method of claims 1 and 4 further characterized by including the additional step of coating the resultant microporous sheet material.
References Cited (Backward Citations)
No citation records indexed.
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