US 11,981,762 B2
Product, and method for producing stretched porous material
Shinya Higuchi, Chiyoda-ku (JP); Shiro Ebata, Chiyoda-ku (JP); and Takehiro Kose, Chiyoda-ku (JP)
Assigned to AGC Inc., Chiyoda-ku (JP)
Filed by AGC Inc., Chiyoda-ku (JP)
Filed on Mar. 17, 2020, as Appl. No. 16/820,839.
Application 16/820,839 is a continuation of application No. PCT/JP2018/035482, filed on Sep. 25, 2018.
Claims priority of application No. 2017-187578 (JP), filed on Sep. 28, 2017.
Prior Publication US 2020/0216591 A1, Jul. 9, 2020
This patent is subject to a terminal disclaimer.
Int. Cl. C08F 214/26 (2006.01); B29C 48/00 (2019.01); C08J 9/22 (2006.01); B29K 27/18 (2006.01)
CPC C08F 214/265 (2013.01) [B29C 48/0018 (2019.02); B29C 48/022 (2019.02); C08J 9/22 (2013.01); B29K 2027/18 (2013.01); C08J 2201/034 (2013.01); C08J 2327/22 (2013.01)] 7 Claims
 
1. A modified polytetrafluoroethylene comprising a polymer having units based on a tetrafluoroethylene, and a polymer having units based on a fluorine-free monomer, wherein the modified polytetrafluoroethylene is having
an endothermic amount ratio R calculated by the following method of 0.75 to 2.00, wherein
the method for calculation of the endothermic amount ratio R is as follows: Using the modified polytetrafluoroethylene having no history of being heated to a temperature of at least 300° C., measurement is conducted by a differential scanning calorimeter at a heating rate of 20° C./min, to obtain a differential thermal curve; in the obtained differential thermal curve, a temperature lower by 2.5° C. from the endothermic peak temperature Tp° C. located above 340° C. is taken as temperature Tm° C.; and endothermic amount S1 in a temperature range of from 310° C. to temperature Tm° C. and endothermic amount S2 in a temperature range of from temperature Tm° C. to 360° C. are obtained; whereupon the ratio of the endothermic amount S2 to the endothermic amount S1 is calculated as the endothermic amount ratio R, and
the fluorine-free monomer is a monomer represented by a formula (1-1) or a formula (1-2):
CH2═CR1—CO—O—R3,  Formula (1-1)
CH2═CR1—O—CO—R4,  Formula (1-2)
where R1 represents a hydrogen or an alkyl, R3 represents an alkyl group, and R4 represents an alkyl group,
where the monomer represented by the formula (1-1) or (1-2) has a content of at least 90 mass % in the polymer having the units based on the fluorine-free monomer,
where the polymer having the units based on the fluorine-free monomer does not contain units based on (meth)acrylic acid,
where the content proportion of the units based on the fluorine-free monomer in the modified polytetrafluoroethylene to the content of all units based on all monomers in the modified polytetrafluoroethylene is from 48 to 100 ppm,
where the modified polytetrafluoroethylene has a breaking strength of from 8.0 N to 28.2 N.