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Porous vinylidene fluoride resin membrane and process for producing same

A technology of ethylene difluoride and its manufacturing method, which is applied in the field of 1, and can solve problems such as excessively large average pore size of porous membranes and maintenance of water permeability

Inactive Publication Date: 2012-07-04
KUREHA KAGAKU KOGYO KK
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

From this point of view, the average pore diameter of the porous membrane disclosed in Patent Document 6 below is too large, and the hollow fiber porous membrane disclosed in Patent Document 8 below has a problem in maintaining the water permeation rate in the continuous filtration operation of turbid water.

Method used

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  • Porous vinylidene fluoride resin membrane and process for producing same
  • Porous vinylidene fluoride resin membrane and process for producing same
  • Porous vinylidene fluoride resin membrane and process for producing same

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0187] Using a Henschel mixer, the weight average molecular weight (Mw) was 6.6×10 5 The substrate is polyvinyl difluoride (PVDF-I) (powder) and Mw is 9.7×10 5 Polyvinylidene fluoride (PVDF-II) (powder) for modifying the crystallization properties of the above-mentioned polyvinyl difluoride (PVDF-II) is mixed according to the ratio of 75% by weight and 25% by weight respectively, and the obtained Mw is 7.4×10 5 PVDF mixture (mixture A; crystallization temperature Tc after film formation = 148.3° C.).

[0188] As the plasticizer, a polyester-based plasticizer (polyester of dibasic acid and diol whose terminal is blocked with benzoic acid; "W-83" manufactured by DIC Co., Ltd., with a number average molecular weight of about 500, according to JIS K7117 -2 (cone-plate type rotational viscometer) measured viscosity at 25° C. is 750 mPa·s).

[0189] Using a co-rotating intermeshing twin-screw extruder (“TEM-26SS” manufactured by Toshiba Machine Co., Ltd., screw diameter 26mm, L / D=...

Embodiment 2

[0198] Except having changed the cooling water bath temperature Tq after melt extrusion into 70 degreeC, it carried out similarly to Example 1, and obtained the polyvinylidene fluoride type hollow fiber porous membrane of this invention.

Embodiment 3

[0200] Use Mw of 4.9×10 5 The polyvinylidene fluoride was used as PVDF-I to obtain PVDF mixture A (crystallization temperature Tc=147.9°C), and the cooling water bath temperature Tq after melt extrusion was changed to 30°C. In the same manner, the polyvinylidene fluoride-based hollow fiber porous membrane of the present invention was obtained.

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Abstract

Disclosed is a porous vinylidene fluoride resin membrane characterized by having two main surfaces, between which a certain thickness is sandwiched, and by having, on the side thereof facing one of the main surfaces, a dense layer that has a small pore diameter and governs the filtration performance, having an asymmetric gradient network structure in which the pore diameter increases continuously from the surface toward the other surface, and satisfying the following requirements (a) to (c): (a) the part of the dense layer which has a thickness of 5 [mu]m and extends continuously from the surface has a porosity (A1) of 60% or higher; (b) the surface has a surface pore diameter (P1) of 0.30 [mu]m or smaller; and (c) the ratio of the amount of water which has passed through in a test length (L) of 200 mm under the conditions of a differential pressure of 100 kPa and a water temperature of 25 DEG C, the water amount being a converted value (Q (m / day)) calculated for an overall porosity (A2) of 80%, to the fourth power of the surface pore diameter (P1) of the surface (P1<4> ([mu]m<4>)), Q / P1<4>, is 5*10<4> (m / day.[mu]m<4>) or higher.

Description

technical field [0001] The present invention relates to a porous membrane made of vinylidene fluoride resin having properties suitable as a porous membrane for separation, especially a membrane for (filtrated) water treatment, and a method for producing the same. Background technique [0002] Since 1,1-vinylidene fluoride resins are excellent in weather resistance, chemical resistance, and heat resistance, their application to porous membranes for separation is being studied. In particular, many proposals have been made regarding (for example, patent documents 1 to 6) regarding porous vinylidene fluoride membranes for use in (filtrated) water treatment, especially tap water production or sewage treatment, as well as their production methods. ). [0003] In addition, the present inventors have also found that by melt-extruding a 1,1-vinylidene fluoride resin having specific molecular weight properties together with a plasticizer and a good solvent for the 1,1-vinylidene fluo...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B01D71/34B01D69/08B29C47/88C02F1/44C08J5/18C08J9/26B29C48/08
CPCY02E60/12C02F1/44D01D5/24B01D2323/20B01D2325/24D01F6/12B01D67/002B01D69/08B01D67/003C02F3/1273B01D67/0027B01D69/02B01D71/34B01D2325/022D01F1/10D01F1/02D01D5/08B29C48/08B29C48/914B29C48/918B29C48/919Y02W10/10B01D69/00
Inventor 多田靖浩高桥健夫
Owner KUREHA KAGAKU KOGYO KK
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