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Expanded porous polytetrafluoroethylene film having elastic recovery property in thickness-wise direction of the film, production process thereof, and use of the porous film

Inactive Publication Date: 2007-07-05
SUMITOMO ELECTRIC IND LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0013] It is an object of the present invention to provide an expanded porous polytetrafluoroethylene film improved in elastic recovery property in its thickness-wise direction, and a production process thereof. Another object of the present invention is also to provide an anisotropically conductive film, cushioning material, intracorporeally implanting material or the like formed by using an expanded porous polytetrafluoroethylene film excellent in elastic recovery property in its thickness-wise direction.
[0018] Since the expanded porous PTFE film according to the present invention is small in residual strain even when it is deformed by applying a load in its thickness-wise direction, it is excellent in shape-recovering ability. The present invention has been led to completion on the basis of these findings.
[0035] Since the expanded porous PTFE films according to the present invention are excellent in elastic recovery property against deformation by compression in the thickness-wise direction, they can be used repeatedly when they are used in applications such as sealing materials and cushioning materials, are convenient for use and can contribute to reductions in cost to a great extent and in discharge of waste matter. The expanded porous PTFE films according to the present invention are also suitable for use as intracorporeally implanting materials having cushioning property. The expanded porous PTFE films according to the present invention are further suitable for use as base films of anisotropically conductive films for inspection of electronic parts required to be used repeatedly.

Problems solved by technology

However, an expanded porous PTFE film obtained under such production conditions has been poor in elastic recovery property in its thickness-wise direction.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

[0097] Into 100 parts by weight of fine PTFE powder (F104, product of Daikin Chemical Co., Ltd.), was incorporated 26 parts by weight of naphtha, and they were mixed. This mixture was left to stand for about 24 hours at 60° C. to get the respective components intimate with each other. The mixture was then compressed within a cylinder having an inner diameter of about 130 mm to preform the mixture. The preform in the form of a column was charged into an extrusion cylinder having an inner diameter of 130 mm and extruded through a T-die into a sheet having a width of 150 mm and a thickness of 2 mm. The resultant sheet-like extrudate was then rolled so as to give a rolling ratio of 4.0 and a film thickness of 0.50 mm.

[0098] The rolled sheet obtained above was stretched at a draw ratio of 2.25 times at 200° C. in a lengthwise direction thereof and then at a draw ratio of 11.0 times at 200° C. in a crosswise direction thereof. The total draw ratio was 24.75 times. The resultant expanded ...

example 2

[0099] Into 100 parts by weight of fine PTFE powder (F104, product of Daikin Chemical Co., Ltd.), was incorporated 26 parts by weight of naphtha, and they were mixed. This mixture was left to stand for about 24 hours at 60° C. to get the respective components intimate with each other. The mixture was then compressed within a cylinder having an inner diameter of about 130 mm to preform the mixture. The preform in the form of a column was then charged into an extrusion cylinder having an inner diameter of 130 mm and extruded through a T-die into a sheet having a width of 150 mm and a thickness of 2 mm. The resultant sheet-like extrudate was then rolled so as to give a rolling ratio of 2.7 and a film thickness of 0.75 mm.

[0100] The rolled sheet obtained above was stretched at a draw ratio of 2.25 times at 200° C. in a lengthwise direction thereof and then at a draw ratio of 11.0 times at 200° C. in a crosswise direction thereof. The total draw ratio was 24.75 times. The resultant expa...

example 3

[0101] Into 100 parts by weight of fine PTFE powder (F104, product of Daikin Chemical Co., Ltd.), was incorporated 26 parts by weight of naphtha, and they were mixed. This mixture was left to stand for about 24 hours at 60° C. to get the respective components intimate with each other. The mixture was then compressed within a cylinder having an inner diameter of about 130 mm to preform the mixture. The resultant preform in the form of a column was charged into an extrusion cylinder having an inner diameter of 130 mm and extruded through a T-die into a sheet having a width of 150 mm and a thickness of 2 mm. This sheet-like extrudate was rolled so as to give a rolling ratio of 2.0 and a film thickness of 1.00 mm.

[0102] The rolled sheet obtained above was stretched at a draw ratio of 2.25 times at 200° C. in a lengthwise direction thereof and then at a draw ratio of 11.0 times at 200° C. in a crosswise direction thereof. The total draw ratio was 24.75 times. The resultant expanded shee...

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Abstract

An expanded porous polytetrafluoroethylene film having residual strain of at most 11.0% as measured after a load required to indent a rod, which is in a columnar form that its outer diameter is at least 2 mm and at least 1.9 times as much as the thickness of the film, and has a smooth plane perpendicular to its axis at a free end surface thereof and a modulus of longitudinal elasticity of at least 1.0×104 kgf / mm2, up to 20% of the film thickness at a strain rate of 100% / min from the free end surface is applied repeatedly 20 times, and a production process of the porous film, in which a step of compressing an expanded porous polytetrafluoroethylene film having a high draw ratio is provided.

Description

TECHNICAL FIELD [0001] The present invention relates to an expanded porous polytetrafluoroethylene film having elastic recovery property in a thickness-wise direction of the film, a production process thereof, and use of the porous film for various applications. The expanded porous polytetrafluoroethylene film according to the present invention can be suitably used as cushioning materials, sealing materials, semiconductor-packaging members, members for inspection of semiconductors, medical implanting material, and the like making good use of its properties such as heat resistance, chemical resistance and elastic recovery property. BACKGROUND ART [0002] An expanded porous polytetrafluoroethylene material produced by stretching of polytetrafluoroethylene (hereinafter abbreviated as “PTFE”) has a microstructure composed of a great number of fibrils (fine fibers) and a great number of nodes connected to each other by the fibrils, and this microstructure forms a porous structure of open-...

Claims

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Application Information

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IPC IPC(8): B32B3/26A61F2/28A47C27/12A61L27/00B29C55/00B29C55/12B32B5/32B32B27/32C08J9/00C09K3/10H01B5/16H01R11/01
CPCB29C55/005B29K2027/18C09K3/10C08J5/18C08J2327/18B29K2105/04B29C48/08B29C48/0018B29C48/305B29C48/9135B29C48/9175Y10T428/249953B29C48/06C08J9/00A61F2/28H01B5/16C08J5/22
Inventor HAYASHI, FUMIHIROOKUDA, YASUHIRO
Owner SUMITOMO ELECTRIC IND LTD
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