Polyphenylene sulfide fiber, filter cloth comprising polyphenylene sulfide fiber, and method for producing polyphenylene sulfide fiber

• US 9,365,954 B2
• Filed: 02/19/2013
• Issued: 06/14/2016
• Est. Priority Date: 02/24/2012
• Status: Active Grant

• Current Assignee: Toray Industries Incorporated
• Original Assignee: Toray Industries Incorporated
• Inventors: Sugimoto, Takeshi, Kaiho, Keiji, Maeda, Koichiro
• Primary Examiner(s): Greene, Jason M
• Assistant Examiner(s): Hawkins, Karla
• Application Number:
  US14/378,542
• Publication Number:
  US 20150013296A1
• Time in Patent Office: 1,211 Days
• Field of Search: 555/16, 555/20, 555/28, 264/164, 528/388
• US Class Current: 1/1
• CPC Class Codes: B01D 2239/0618 Non-woven
• CPC Class Codes: B01D 39/083 of organic material
• CPC Class Codes: B29C 48/05 Filamentary, e.g. strands
• CPC Class Codes: D01D 5/12 Stretch-spinning methods D01D5/098 takes precedence finishing by stretching D02J1/22
• CPC Class Codes: D01F 6/765 from polyarylene sulfides
• CPC Class Codes: D04H 1/4326 Condensation or reaction polymers
• CPC Class Codes: D04H 1/46 by needling or like operations to cause entanglement of fibres D04H1/45 takes precedence; needling machines D04H18/00
• CPC Class Codes: D04H 1/492 by fluid jet D04H1/49 takes precedence

Abstract

The present invention provides: a polyphenylene sulfide fiber that has excellent tensile strength; and a polyphenylene sulfide fiber that decreases in toughness to a small extent even when subjected to a long-term heat treatment and has excellent tensile strength. The polyphenylene sulfide fiber according to the present invention is characterized by comprising a polyphenylene sulfide resin having a weight average molecular weight of 50000 to 80000 inclusive, having a rigid amorphous content of 50% or more, and having a crystal size of 5 nm or more in the direction of a (111) crystal plane.

Claims

1. A polyphenylene sulfide fiber comprising a polyphenylene sulfide resin having a weight average molecular weight of 50500 or more and 53000 or less, the polyphenylene sulfide fiber having a rigid amorphous content of 50% or more and a crystallite size in a direction of a (111) crystal plane of 5 nm or more.

2. The polyphenylene sulfide fiber according to claim 1, wherein the tensile strength of the polyphenylene sulfide fiber is 5.0 cN/dtex or more and the rate of decrease in toughness of the polyphenylene sulfide fiber after a 24-week heat treatment at a temperature of 180°

C. is 30% or less.

3. A filter cloth comprising the polyphenylene sulfide fiber recited in claim 1.

4. A method for producing a polyphenylene sulfide fiber, comprising:

melting a polyphenylene sulfide resin having a weight average molecular weight of 50500 or more and 53000 or less at 280°

C. or higher and 340°

C. or lower and extruding the polyphenylene sulfide resin through a spinneret into an undrawn yarn, collecting the undrawn yarn at a haul-off rate of 500 m/minute or more and 5000 m/minute or less, and then hot-drawing the undrawn yarn at 2 times or more and 4 times or less, subjecting the yarn to a fixed-length heat treatment at 190°

C. or higher and 270°

C. or lower for 4 seconds or longer and 12 seconds or shorter, and thereafter subjecting the yarn to a relaxed heat treatment at 50°

C. or higher and 150°

C. or lower for 5 minutes or longer and 60 minutes or shorter and imparting crimp, and cutting the yarn into a predetermined length.