Separation membrane and method for producing same

Patent metadata

Field	Value
Publication number	US-10702834-B2
Application number	US-201515324399-A
Country	US
Kind code	B2
Filing date	Jul 7, 2015
Priority date	Jul 7, 2014
Publication date	Jul 7, 2020
Grant date	Jul 7, 2020

Abstract

An object of the present invention is to provide a separation membrane having high mechanical strength and being less likely to cause clogging and capable of continuously maintaining high water permeation performance. The present invention relates to a separation membrane characterized in that the average diameter D 1 of a spherical structure in a region within 10 μm from a first surface in a separation membrane having a spherical structure layer formed of a thermoplastic resin and the average diameter D 2 of a spherical structure in a region of 10 μm to 20 μm from a second surface satisfy the relational expression of D 1 >D 2 and the average diameter D 1 and the average diameter D 3 of a spherical structure in a third region satisfy the relational expression of 1.10<D 1 /D 3 <4.00.

First claim

The invention claimed is:

1. A separation membrane layer having a first surface for contacting liquid to be treated and a second surface disposed on the opposite side of the separation membrane layer through which treated liquid exits, wherein
the separation membrane layer comprises solid spherical structures formed of a polyvinylidene fluoride-based resin,
an average diameter D 1 of the solid spherical structures S 1 in a region within 10 μm from the first surface and an average diameter D 2 of the solid spherical structures S 2 in a region of 10 μm to 20 μm from the second surface satisfy a relational expression of D 1 >D 2 ,
the average diameter D 1 and an average diameter D 3 of the solid spherical structures S 3 in a region of 10 μm to 20 μm from the first surface satisfy a relational expression of
10<D 1 /D 3 <4.00, and
the separation membrane layer has an entire thickness of from 40 μm to 500 μm.

2. The separation membrane according to claim 1 , wherein the average diameter D 1 and the average diameter D 3 satisfy a relational expression of 0.00 μm<(D 1 −D 3 )<2.00 μm.

3. The separation membrane according to claim 1 , wherein the average diameter D 1 is from 2.00 μm to 4.00 μm, and the average diameter D 3 is 0.10 μm or more and less than 2.00 μm.

4. The separation membrane according to claim 1 , wherein the average diameter D 3 and the average diameter D 2 satisfy a relational expression of −0.30 μm<(D 3 −D 2 )<0.30 μm.

5. The separation membrane according to claim 2 , wherein the average diameter D 3 and the average diameter D 2 satisfy a relational expression of −0.30 μm<(D 3 −D 2 )<0.30 μm.

6. The separation membrane according to claim 1 , wherein the average diameter D 1 and the average diameter D 3 satisfy a relational expression of 1.32<D 1 /D 3 <3.24.

Assignees

• Toray Industries

Inventors

• Iwai Kenta
• Ishizaki Toshiyuki
• Kitade Tamotsu
• Komori Kenji
• Hanakawa Masayuki

Classifications

• B01D67/0013

  Casting processes · CPC title

• B01D69/06

  Flat membranes · CPC title

• D01F6/12

  from polymers of fluorinated hydrocarbons · CPC title

• D01D5/24

  with a hollow structure; Spinnerette packs therefor (D01D5/38 takes precedence; producing tubes of plastic material B29D; addition of agents forming hollow filaments D01F1/08) · CPC title

• C08J2327/16

  Homopolymers or copolymers of vinylidene fluoride · CPC title