US3929950A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for producing porous synthetic resin film and sheet
Assignee: Kureha Corp
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Filing: 1973-06-21
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Granted: 1975-12-30
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Expires: 1993-06-21
Abstract
Abstract A process for producing a porous synthetic resin film or sheet which comprises stretching, at least uniaxially, a melt molded article of a synthetic resin composition containing at least 50% by weight of a powder of an inorganic material which is capable of being eluted and removing the powder of inorganic material from the stretched article by elution with a solvent for the inorganic material is disclosed the stretching forms fine cracks between the resin and the inorganic material.
Inventors
- 👤 Tadashi Nakamura
- 👤 Hisami Hagiwara
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 23:55
CPC Classifications
B; B29; B29C; B29C67/00; B29C67/20; B29C67/202; C; C08; C08J; C08J9/00; C08J9/26
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
210 words
IN A PROCESS FOR PRODUCING A POROUS SYNTHETIC THERMOPIASTIC RESIN FILM OR SHEET WHICH EXHIBITS A CONTINUOUS POROUS STRUCTURE WHICH COMPRISES ELUTING A MELT MOLDED ARTICLE OF A SYNTHETIC THERMOPLASTIC RESIN COMPOSITION WHICH CONSISTS ESSENTIALY OF A SYNTHETIC THERMOPLASTIC RESIN SELECTED FROM THE GROUP CONSISTING OF A POLYOLEFIN AND POLYVINYLIDENE FLUORIDE CONTAINING 50% TO 8% BY WEIGHT OF CALCIUM SULFITE POWDER AS ROD-SHAPED CRYSTALS HAVING A MAXIMUM WIDTH OF 1 TO 10 U AND A MINIMUM LENGTH OF 5 TO 100 U TO REMOVE THE CALCIUM SULFITE FROM THE STRECHED ARTICLE BY ELUTION WITH A SOLVENT FOR THE CALCIUM SULFITE, THE IMPROVEMENT COMPRISING STRETCHING SAID MELT MOLDED ARTICLE UNIAXIALLY AT A STRETCH RATIO OF 3 TO 10 AT A TEMPERATURE OF FROM ROOM TEMPERATURE OF 150*C PRIOR TO THE ELUTION OF THE CALCIUM SULFITE, SAID STRETCHING BEING TO AN EXTENT EXCEEDING THE ELASTIC LIMIT OF THE RESIN BUT NOT EXCEEDING THE MAXIUM LIMIT OVER WHICH THE MELT MOLDED ARTICLE BREAKS TO THEREBY FORM FINE CRACKS BETWEEN THE RESIN AND THE CALCIUM SULFITE TO UNCREASE THE EASE OF ELUTION, WHEREBY SAID CONTINUOUS POROUS STRUCTURE IS OBTAINED, THE SPECIFIC GRAVITY OF THE STRETCHED FILM DECREASING TO LESS THAN 1, THE SPECIFIC GRAVIT OF SAID FILM PRIOR TO STRETCHING BEING 1.39 TO 1.90
Claim 2
Dependent Claim
210 words
IN A PROCESS FOR PRODUCING A POROUS SYNTHETIC THERMOPIASTIC RESIN FILM OR SHEET WHICH EXHIBITS A CONTINUOUS POROUS STRUCTURE WHICH COMPRISES ELUTING A MELT MOLDED ARTICLE OF A SYNTHETIC THERMOPLASTIC RESIN COMPOSITION WHICH CONSISTS ESSENTIALY OF A SYNTHETIC THERMOPLASTIC RESIN SELECTED FROM THE GROUP CONSISTING OF A POLYOLEFIN AND POLYVINYLIDENE FLUORIDE CONTAINING 50% TO 8% BY WEIGHT OF CALCIUM SULFITE POWDER AS ROD-SHAPED CRYSTALS HAVING A MAXIMUM WIDTH OF 1 TO 10 U AND A MINIMUM LENGTH OF 5 TO 100 U TO REMOVE THE CALCIUM SULFITE FROM THE STRECHED ARTICLE BY ELUTION WITH A SOLVENT FOR THE CALCIUM SULFITE, THE IMPROVEMENT COMPRISING STRETCHING SAID MELT MOLDED ARTICLE UNIAXIALLY AT A STRETCH RATIO OF 3 TO 10 AT A TEMPERATURE OF FROM ROOM TEMPERATURE OF 150*C PRIOR TO THE ELUTION OF THE CALCIUM SULFITE, SAID STRETCHING BEING TO AN EXTENT EXCEEDING THE ELASTIC LIMIT OF THE RESIN BUT NOT EXCEEDING THE MAXIUM LIMIT OVER WHICH THE MELT MOLDED ARTICLE BREAKS TO THEREBY FORM FINE CRACKS BETWEEN THE RESIN AND THE CALCIUM SULFITE TO UNCREASE THE EASE OF ELUTION, WHEREBY SAID CONTINUOUS POROUS STRUCTURE IS OBTAINED, THE SPECIFIC GRAVITY OF THE STRETCHED FILM DECREASING TO LESS THAN 1, THE SPECIFIC GRAVIT OF SAID FILM PRIOR TO STRETCHING BEING 1.39 TO 1.90
Claim 3
Dependent Claim
37 words
A process accordingly to claim 1 wherein said calcium sulfite powder is monocrystal in form with a smooth surface, whereby exfoliation is increased between said calcium sulfite powder and said synthetic thermoplastic resin, resulting in increased porosity.
Claim 4
Dependent Claim
40 words
A process according to claim 1 whereby during said stretching said rod-like monocrystal calcium sulfite powder is oriented in the direction of stretching thereby causing shear in the boundary surface between the calcium sulfite powder and said synthetic thermoplastic resin.
Claim 5
Dependent Claim
25 words
A process according to claim 1 wherein said synthetic thermoplastic resin composition is rendered porous upon stretching, the porosity being further increased by said elution.
Claim 6
Dependent Claim
14 words
A process according to claim 1 consisting of the steps of stretching and eluting.
Claim 7
Dependent Claim
12 words
The process of claim 1, wherein said synthetic thermoplastic resin is polypropylene.
Claim 8
Dependent Claim
197 words
In a process for producing a porous synthetic thermoplastic resin film or sheet which exhibits a continuous porous structure which comprises eluting a melt molded article of a synthetic thermoplastic resin composition which consists essentially of polyethylene containing 50 to 85% by weight of calcium sulfite powder as rod-shaped crystals having a maximum width of 1 to 10 Mu and a minimum length of 5 to 100 Mu to remove the calcium sulfite from the stretched article by elution with a solvent for the calcium sulfite, the improvement comprising stretching said melt molded article uniaxially at a stretch ratio of 3 to 10 and at a temperature of from Room temperature to 150*C prior to the elution of the calcium sulfite, said stretching being to an extent exceeding the elastic limit of the resin but not exceeding the maximum limit over which the melt molded article breaks to thereby form fine cracks between the resin and the calcium sulfite to increase the ease of elution, whereby said continuous porous structure is obtained, the specific gravity of the stretched film decreasing to less than 1, the specific gravity of said film prior to stretching being 1.39 to 1.90.
Claim 9
Dependent Claim
197 words
In a process for producing a porous synthetic thermoplastic resin film or sheet which exhibits a continuous porous structure which comprises eluting a melt molded article of a synthetic thermoplastic resin composition which consists essentially of polyethylene containing 50 to 85% by weight of calcium sulfite powder as rod-shaped crystals having a maximum width of 1 to 10 Mu and a minimum length of 5 to 100 Mu to remove the calcium sulfite from the stretched article by elution with a solvent for the calcium sulfite, the improvement comprising stretching said melt molded article uniaxially at a stretch ratio of 3 to 10 and at a temperature of from Room temperature to 150*C prior to the elution of the calcium sulfite, said stretching being to an extent exceeding the elastic limit of the resin but not exceeding the maximum limit over which the melt molded article breaks to thereby form fine cracks between the resin and the calcium sulfite to increase the ease of elution, whereby said continuous porous structure is obtained, the specific gravity of the stretched film decreasing to less than 1, the specific gravity of said film prior to stretching being 1.39 to 1.90.
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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) | 1978-12-29 | 1979-06-30 | 1979-12-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-12-29 | 1983-06-30 | 1983-12-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-12-29 | 1987-06-30 | 1987-12-30 | $7700.00 | Window Closed / Lapsed |