Process for producing modified molded article, molded article, diaphragm, and diaphragm valve

Patent metadata

Field	Value
Publication number	US-11072672-B2
Application number	US-201716329059-A
Country	US
Kind code	B2
Filing date	Aug 1, 2017
Priority date	Aug 30, 2016
Publication date	Jul 27, 2021
Grant date	Jul 27, 2021

Abstract

The invention provides a process for producing a modified molded article capable of providing a diaphragm that is less likely to generate particles. The process for producing a modified molded article includes: molding modified polytetrafluoroethylene containing a tetrafluoroethylene unit and a modifying monomer unit based on a modifying monomer copolymerizable with tetrafluoroethylene to provide a molded article; and irradiating the molded article with not lower than 30 kGy but lower than 70 kGy of radiation at 270° C. to 310° C. to provide a modified molded article.

First claim

The invention claimed is:

1. A process for producing a modified molded article, comprising:
molding modified polytetrafluoroethylene containing a tetrafluoroethylene unit and a modifying monomer unit based on a modifying monomer copolymerizable with tetrafluoroethylene to provide a molded article; and
irradiating the molded article with not lower than 30 kGy but lower than 70 kGy of radiation at 270° C. to 310° C. to provide a modified molded article,
wherein the modified polytetrafluoroethylene has non-processability and a standard specific gravity defined in ASTM D4895-89 of 2.13 to 2.23.

2. The production process according to claim 1 ,
wherein the modified polytetrafluoroethylene contains 0.001 to 1% by mass of the modifying monomer unit relative to a sum of amounts of the tetrafluoroethylene unit and the modifying monomer unit.

3. The production process according to claim 1 ,
wherein the modified polytetrafluoroethylene has a secondary melting point of 320° C. to 329° C.

4. The production process according to claim 1 , further comprising
machining the molded article after the molded article is provided and before irradiation.

5. The production process according to claim 1 , further comprising
machining the modified molded article after the modified molded article is provided.

6. The production process according to claim 1 ,
wherein the modified molded article is a diaphragm.

7. A molded article comprising modified polytetrafluoroethylene,
the modified polytetrafluoroethylene containing a tetrafluoroethylene unit, modifying monomer unit based on a modifying monomer copolymerizable with tetrafluoroethylene,
wherein the modified polytetrafluoroethylene constituting the molded article contains tertiary carbon, the tertiary carbon being present in an amount of 0.035 to 0.100 mol % relative to a sum of amounts of the tetrafluoroethylene unit and the modifying monomer unit, and
wherein the modified polytetrafluoroethylene has non-melt-processability and a standard specific gravity defined in ASTM D4895-89 of 2.13 to 2.23.

8. The molded article according to claim 7 ,
wherein the modified polytetrafluoroethylene contains 0.001 to 1% by mass of the modifying monomer unit relative to the sum of the amounts of the tetrafluoroethylene unit and the modifying monomer unit.

9. A diaphragm comprising the molded article according to claim 7 .

10. A diaphragm obtainable by irradiating modified polytetrafluoroethylene with not lower than 30 kGy but lower than 70 kGy of radiation at 270° C. to 310° C.,
wherein the modified polytetrafluoroethylene has non-melt-processability and a standard specific gravity defined in ASTM D4895-89 of 2.13 to 2.23.

11. A diaphragm valve comprising a valve seat and the diaphragm according to claim 9 .

12. The diaphragm valve according to claim 11 ,
wherein the valve seat comprises a tetrafluoroethylene/perfluoro alkyl vinyl ether copolymer.

13. The production process according to claim 1 ,
wherein the molded article is irradiated at 280° C. to 310° C. to provide the modified molded article.

14. The production process according to claim 1 ,
wherein the molded article is irradiated at 280° C. to 300° C. to provide the modified molded article.

Assignees

• Daikin Ind Ltd

Inventors

• Imamura Hitoshi
• FUNAOKA Tatsuya
• Shimono Takeshi

Classifications

• H10P72/0402

  Apparatus for fluid treatment (H10P72/0441, H10P72/0448 take precedence) · CPC title

• F16K7/14 Primary

  arranged to be deformed against a flat seat · CPC title

• C08J7/00

  Chemical treatment or coating of shaped articles made of macromolecular substances (coating with metallic material C23C; electrolytic deposition of metals C25) · CPC title

• B29K2027/18

  PTFE, i.e. polytetrafluoroethylene {, e.g. ePTFE, i.e. expanded polytetrafluoroethylene} · CPC title

• C08J2327/18

  Homopolymers or copolymers of tetrafluoroethylene · CPC title