US4620955A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Polyethylene microporous membrane and a process for the production of the same
Assignee: Tonen General Sekiyu KK
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Filing: 1986-02-25
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Granted: 1986-11-04
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Expires: 2006-02-25
Abstract
Abstract A polyethylene microporous membrane having a thickness of at most 10 μm, a breaking strength of at least 200 kg/cm 2 and a porosity of at least 30% is produced by heating and dissolving polyethylene having a weight average molecular weight of at least 5×10 5 in a solvent, forming a gel sheet from the resulting solution, subjecting the gel sheet to a solvent removal treatment to adjust the amount of the solvent in the gel sheet to 10 to 80% by weight, heating and stretching the sheet and then removing the residual solvent therefrom.
Inventors
- 👤 Koichi Kono
- 👤 Shoichi Mori
- 👤 Kenji Miyasaka
- 👤 Jyoichi Tabuchi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 11:23
CPC Classifications
C; C08; C08J; C08J5/00; C08J5/18; B; B01; B01D; B01D67/00; B01D67/0002; B01D67/0009; B01D67/00091; B01D67/0023; B01D67/0025; B01D67/0027; B01D67/0039; B01D67/0046; B01D71/00; B01D71/06; B01D71/26; B01D71/261; B01D2323/00; B01D2323/08; B01D2323/081; B01D2323/12; B01D2325/00; B01D2325/02; B01D2325/0283; B01D2325/04; C08J2323/00; C08J2323/02; C08J2323/04; C08J2323/06; Y; Y10; Y10S; Y10S264/00; Y10S264/71; Y10S521/00; Y10S521/918; Y10T; Y10T428/00; Y10T428/249921; Y10T428/249953; Y10T428/249978
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
109 words
A process for the production of a polyethylene microporous membrane having a thickness of at most 10 μm, a breaking strength of at least 200 kg/cm 2 and a porosity of at least 30%, which comprises heating and dissolving polyethylene having a weight average molecular weight of at least 5×10 5 in a solvent, forming a gel sheet from the resulting solution, subjecting the gel sheet to a solvent removal treatment to adjust the amount of the solvent removal treatment to adjust the amount of the solvent in the gel sheet to 10 to 80% by weight, heating and stretching the sheet and then removing the residual solvent therefrom.
Claim 2
Dependent Claim
109 words
A process for the production of a polyethylene microporous membrane having a thickness of at most 10 μm, a breaking strength of at least 200 kg/cm 2 and a porosity of at least 30%, which comprises heating and dissolving polyethylene having a weight average molecular weight of at least 5×10 5 in a solvent, forming a gel sheet from the resulting solution, subjecting the gel sheet to a solvent removal treatment to adjust the amount of the solvent removal treatment to adjust the amount of the solvent in the gel sheet to 10 to 80% by weight, heating and stretching the sheet and then removing the residual solvent therefrom.
Claim 3
Dependent Claim
42 words
The process of claim 1, wherein the solvent is at least one member selected from the group consisting of aliphatic or cyclic hydrocarbons such as nonane, decane, undecane, dodecane, decalin and paraffin oils and mineral oil fractions having boiling points corresponding thereto.
Claim 4
Dependent Claim
16 words
The process of claim 2, wherein the solvent is a non-volatile solvent such as paraffin oils.
Claim 5
Dependent Claim
21 words
The process of claim 1, wherein the heating and dissolving is carried out at a temperature of 140° to 250° C.
Claim 6
Dependent Claim
18 words
The process of claim 1, wherein the solution has a polyethylene content of 1 to 10% by weight.
Claim 7
Dependent Claim
65 words
The process of claim 1, wherein the forming of a gel sheet is carried out by subjecting the polyethylene solution to extrusion through a die or to spreading over a support, cooling and gelling at a temperature below the gelling temperature and a cooling rate of at least 50° C./min and then forming into a gel sheet with a thickness of 0.1 to 5 mm.
Claim 8
Dependent Claim
13 words
The process of claim 6, wherein the temperature is 15° to 25° C.
Claim 9
Dependent Claim
27 words
The process of claim 1, wherein the solvent removal treatment is carried out by immersing the gel sheet in a readily volatile solvent to extract the solvent.
Claim 10
Dependent Claim
57 words
The process of claim 7, wherein the readily volatile solvent is at least one member selected from the group consisting of hydrocarbons such as pentane, hexane and heptane, chlorinated hydrocarbons such as methylene chloride and carbon tetrachloride, fluorinated hydrocarbons such as trifluoroethane, ethers such as diethyl ether and dioxane and alcohols such as methanol, ethanol and propanol.
Claim 11
Dependent Claim
43 words
The process of claim 1, wherein the solvent removal treatment is carried out in such a manner that the gel sheet shrinks with a shrinkage of at least 50% in the thickness direction and at most 20% in the longitudinal and lateral directions.
Claim 12
Dependent Claim
40 words
The process of claim 1, wherein the heating and stretching is carried out biaxially simultaneously or in sequence at a temperature of from the crystal dispersion point to the crystal melting point of the polyethylene of the base stock sheet.
Claim 13
Dependent Claim
13 words
The process of claim 11, wherein the temperature is 90° to 140° C.
Claim 14
Dependent Claim
20 words
The process of claim 11, wherein the stretching is carried out with a surface magnification of at least 10 times.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-11-03 | 1990-05-05 | 1990-11-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-11-03 | 1994-05-05 | 1994-11-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-11-03 | 1998-05-05 | 1998-11-04 | $7700.00 | Window Closed / Lapsed |