US4921652A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for producing a porous film
Assignee: Mitsui Chemicals Inc
•
Filing: 1988-08-08
•
Granted: 1990-05-01
•
Expires: 2008-08-08
Abstract
Abstract A process for producing a porous film having practically sufficient mechanical strengths, good flexibility, uniform fine pores and high moisture vapor permeability, and further an extremely thin porous film, which process comprises blending 30 to 80 parts by weight of an inorganic fine powder having a specific surface area of 15 m 2 /g or less and an average particle size of 0.4 to 4 μm with 20 to 70 parts by weight of a polyolefin resin, followed by melt-molding the resulting blend into a film and then stretching the film to 2 to 7 times the original length at least in the uniaxial direction.
Inventors
- 👤 Syoichi Tsuji
- 👤 Syoichi Ito
- 👤 Shuji Matsumura
- 👤 Hisatosi Suzuki
- 👤 Michiyasu Ito
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 09:35
CPC Classifications
B; B29; B29C; B29C55/00; B29C55/02; C; C08; C08J; C08J5/00; C08J5/18; C08K; C08K3/00; C08K3/01; C08K3/013; C08J2323/00; C08J2323/02; C08J2323/04; Y; Y10; Y10S; Y10S264/00; Y10S264/47
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
125 words
A process for producing a porous film which consists essentially of blending 30 to 80 parts by weight of an inorganic fine powder having a specific surface area of 15 m 2 /g or less, an average particle size of 0.4 to 4 μm and a spherical particle shape, selected from the group consisting of precipitated calcium carbonate, barium sulfate, precipitated barium sulfate, magnesium carbonate, magnesium oxide, silica, aluminum hydroxide and alumina with 20 to 70 parts by weight of a polyolefin resin, these parts by weight being based on 100 parts by weight of the blend, followed by melt-molding the resulting blend into a film and then stretching the film to 2 to 7 times the original length at least in the uniaxial direction.
Claim 2
Dependent Claim
125 words
A process for producing a porous film which consists essentially of blending 30 to 80 parts by weight of an inorganic fine powder having a specific surface area of 15 m 2 /g or less, an average particle size of 0.4 to 4 μm and a spherical particle shape, selected from the group consisting of precipitated calcium carbonate, barium sulfate, precipitated barium sulfate, magnesium carbonate, magnesium oxide, silica, aluminum hydroxide and alumina with 20 to 70 parts by weight of a polyolefin resin, these parts by weight being based on 100 parts by weight of the blend, followed by melt-molding the resulting blend into a film and then stretching the film to 2 to 7 times the original length at least in the uniaxial direction.
Claim 3
Dependent Claim
23 words
A process according to claim 1 wherein said polyolefin resin is a linear low density polyethylene resin or a blend containing the same.
References Cited (Backward Citations)
US3929950A
Cited
US3903234A
Cited
US4187210A
Cited
US4350655A
Cited
GB2027637A
Cited
FR2505251A1
Cited
EP0066672A2
Cited
GB2151538A
Cited
US4704238A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-04-30 | 1993-10-30 | 1994-05-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-04-30 | 1997-10-30 | 1998-05-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-04-30 | 2001-10-30 | 2002-05-01 | $7700.00 | Window Closed / Lapsed |