Extra-fine fiber sheet

• US 10,106,923 B2
• Filed: 03/27/2014
• Issued: 10/23/2018
• Est. Priority Date: 09/28/2011
• Status: Active Grant

• Current Assignee: Kuraray Company Limited
• Original Assignee: Kuraray Company Limited
• Inventors: Hosoya, Takayoshi, Hayakawa, Tomohiro, Kawai, Hiroyuki, Hayashi, Hideo
• Primary Examiner(s): Choi, Peter Y
• Application Number:
  US14/227,557
• Publication Number:
  US 20140213135A1
• Time in Patent Office: 1,671 Days
• Field of Search: 442341
• CPC Class Codes: D04H 1/43838 Ultrafine fibres, e.g. microfibres
• CPC Class Codes: D04H 1/728 by electro-spinning electro-spinning methods and apparatus D01D5/0007
• CPC Class Codes: D04H 3/016 characterised by the fineness
• CPC Class Codes: Y10T 442/615 Strand or fiber material is blended with another chemically different microfiber in the same layer

Abstract

Provided is an extra-fine fiber sheet including an extra-fine fiber assembly including extra-fine fibers having an average fiber diameter of 500 nm or smaller. The extra-fine fiber sheet includes an extra-fine fiber assembly. The assembly includes a solvent-spinnable polymer (A) having a weight average molecular weight of 5,000 to 100,000 as a main component and a polymer (B) having a weight average molecular weight equal to or more than 10 times as large as that of the polymer (A) as an accessory component; and the assembly includes constituent fibers having an average fiber diameter of 10 to 500 nm. The polymer (A) may be a non-conductive polymer, and the polymer (B) may be a thickening polymer.

Claims

1. An extra-fine fiber sheet comprising an extra-fine fiber assembly, wherein the assembly includes a solvent-spinnable polymer (A) having a weight average molecular weight of 5,000 to 100,000 as a main component and a polymer (B) having a weight average molecular weight equal to or more than 10 times as large as that of the polymer (A) as an accessory component;

the polymer (A) is (i) an ethylene-vinyl alcohol copolymer or (ii) a polyamide including a 1,9-nonanediamine unit, a 2-methyl-1,8-octanediamine unit or both, as a diamine unit;

the polymer (B) is a polyethylene oxide, a polyethylene glycol or a polyacrylamide;

the sheet has a composition ratio of the polymer (A) to the polymer (B) of (A);

(B)=10;

1 to 10,000;

1;

the assembly comprises constituent fibers having an average fiber diameter of 10 to 500 nm; and

the assembly has 5 or fewer beads generated per 100 μ

m² on a cross section of the extra-fine fiber assembly photographed at a magnification of 5,000, and the beads are unfiberized particulate material having a size equal to or greater than 5 times as large as the average fiber diameter.

2. The extra-fine fiber sheet according to claim 1, wherein

the polymer (A) is a non-conductive polymer;

the polymer (B) is a thickening polymer;

or

the polymers (A) and (B) are a non-conductive polymer and a thickening polymer, respectively.

3. The extra-fine fiber sheet according to claim 1, wherein the polymer (A) is the polyamide, and the polyamide comprises a dicarboxylic acid unit and a diamine unit, the dicarboxylic acid unit comprising terephthalic acid unit at a percentage of 60% by mole or more, and the diamine unit comprising 1,9-nonanediamine unit, 2-methyl-1,8octanediamine unit or both at a percentage of 60% by mole or more.

4. The extra-fine fiber sheet according to claim 1, wherein the polymer (B) has a weight average molecular weight of 500,000 or higher.

5. The extra-fine fiber sheet according to claim 1, wherein the extra-fine fiber assembly is an electro-spun fiber.

7. The extra-fine fiber sheet according to claim 1, wherein the assembly comprises constituent fibers having an average fiber diameter of 10 to 400 nm.

8. The extra-fine fiber sheet according to claim 1, wherein the assembly comprises constituent fibers having an average fiber diameter of 10 to 300 nm.

9. The extra-fine fiber sheet according to claim 1, wherein the assembly comprises constituent fibers having an average fiber diameter of 10 to 250 nm.

10. The extra-fine fiber sheet according to claim 1, wherein the sheet has a composition ratio of the polymer (A) to the polymer (B) of (A):

(B)=10;

1 to 9000;

1.

11. The extra-fine fiber sheet according to claim 1, wherein the sheet has a composition ratio of the polymer (A) to the polymer (B) of (A):

(B)=10;

1 to 8000;

1.

12. The extra-fine fiber sheet according to claim 1, wherein the sheet has a liquid absorption such that when a 0.02 mL drop of pure water is placed onto the center of a 3 cm square sheet on an extra-fine fiber assembly side of the sheet, the sheet absorbs the drop of pure water in a time of 700 seconds or less.

13. The extra-fine fiber sheet according to claim 1, wherein the sheet has a liquid absorption such that when a 0.02 mL drop of pure water is placed onto the center of a 3 cm square sheet on an extra-fine fiber assembly side of the sheet, the sheet absorbs the drop of pure water in a time of 600 seconds or less.

6. An extra-fine fiber sheet comprising an extra-fine fiber assembly, wherein the assembly consists essentially of:

a solvent-spinnable polymer (A) having a weight average molecular weight of 5,000 to 100,000 as a main component;

a polymer (B) having a weight average molecular weight equal to or more than 10 times as large as that of the polymer (A) as an accessory component; and

optionally one or more additives selected from the group consisting of a plasticizer, an antioxidant, a slip additive, an ultraviolet absorber, a light stabilizer, an antistatic agent, a flame retardant, a lubricant, a crystallization speed retarder, and a colorant;

wherein;

the polymer (A) is (i) an ethylene-vinyl alcohol copolymer or (ii) a polyamide including a 1,9-nonanediamine unit, a 2-methyl-1,8-octanediamine unit or both, as a diamine unit;

the polymer (B) is a polyethylene oxide, a polyethylene glycol or a polyacrylamide;

the sheet has a composition ratio of the polymer (A) to the polymer (B) of (A);

(B)=10;

1 to 10,000;

1;

the assembly comprises constituent fibers having an average fiber diameter of 10 to 500 nm; and

the assembly has 5 or fewer beads generated per 100 μ

m² on a cross section of the extra-fine fiber assembly photographed at a magnification of 5,000, and the beads are unfiberized particulate material having a size equal to or greater than 5 times as large as the average fiber diameter.