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Vinylidene fluoride resin hollow fiber porous membrane and method for production thereof

A technology of vinylidene fluoride and its manufacturing method, which is applied in the direction of chemical instruments and methods, membranes, membrane technology, etc., and can solve problems such as low particle or bacteria removal performance and increased water permeability.

Inactive Publication Date: 2008-09-10
KUREHA KAGAKU KOGYO KK
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

But according to the further research results of the present inventors, it is found that the hollow fiber porous membrane of vinylidene fluoride resin obtained by this method has indeed significantly increased the water permeability, based on the bubble point method / halfdry (halfdry) method (ASTM. F316 and ASTM·E1294) The main peak of the pore size distribution measured near the large pore side tends to show other small sub-peaks, and it is found that the pinholes may cause fine particles or bacteria in (filtered) water treatment Poor removal performance of

Method used

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  • Vinylidene fluoride resin hollow fiber porous membrane and method for production thereof
  • Vinylidene fluoride resin hollow fiber porous membrane and method for production thereof
  • Vinylidene fluoride resin hollow fiber porous membrane and method for production thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0079] The weight average molecular weight (Mw) is 4.12×10 5 The main body of polyvinylidene fluoride (PVDF) (powder) and Mw is 9.36×10 5 Polyvinylidene fluoride (PVDF) (powder) used for modifying the crystallinity properties of 95% by weight and 5% by weight was mixed using a Henschel mixer to obtain a Mw of 4.38×10 5 PVDF mixture.

[0080]An adipic acid-based polyester plasticizer ("PN-150" manufactured by Soden Chemical Industry Co., Ltd.) as an aliphatic polyester and N-methylpyrrolidone (NMP) as a solvent were mixed at 77.5% by weight / 22.5% by weight % of the mixture was stirred and mixed at room temperature to obtain a plasticizer-solvent mixture.

[0081] Using a twin-screw extruder that rotates in the same direction ("BT-30" manufactured by Plastic Engineering Research Institute, screw diameter 30mm, L / D=48), from the powder set at a position 80mm away from the most upstream part of the barrel The supply part supplies the PVDF mixture, and according to the ratio of ...

Embodiment 2

[0088] The ratio of the two in the plasticizer-solvent mixture was changed to 82.5% by weight / 17.5% by weight, the discharge amount of the raw material was changed to 16.7g / min, and the air flow rate from the vent hole provided in the center of the nozzle was changed to 9.5mL / min. The temperature of the water bath is changed to 40°C, the pulling speed is changed to 11.0m / min, the stretching ratio is changed to 1.85 times, the relaxation in the first stage is changed to damp heat at 90°C, 8%, and the relaxation in the second stage is changed to dry heat at 140°C, 4%. , except that, in the same manner as in Example 1, a hollow fiber porous membrane was obtained.

Embodiment 3

[0090] Change the discharge rate to 15.0g / min, the air flow rate from the air hole provided in the center of the nozzle to 6.5mL / min, the pulling speed to 10.0m / min, the heat treatment temperature to 80°C, and the first-stage relaxation to A hollow fiber porous membrane was obtained in the same manner as in Example 2 except that it was dry heat at 140° C. and 8%, and the relaxation in the second stage was changed to dry heat at 140° C. and 2%.

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Abstract

Disclosed is a vinylidene fluoride resin follow fiber porous membrane which has a micropore (A) having a pore size (average pore size) appropriate for the treatment of (filtered) water and a more uniform pore size distribution, has a good microparticle (bacterium)-blocking efficiency through the micropore, and has a large transmissibility (B). The membrane comprises a vinylidene fluoride resin porous membrane in the form of a follow fiber and has the following characteristics (A) and (B): [Pmax(1m) / Pm], which is the ratio of the maximum pore size (Pmax(1m)) as determined by the bubble point method at the length of 1 m to the average pore size (Pm) as determined by the half-dry method (Pm = 0.05 to 0.20 [mu]m), is 4.0 or less; and (B) [F(L=200 mm, v=70%) / Pm<2>], which is the ratio of the converted value (F)(L=200 mm, v=70%)(m / day) in terms of void content (v=70%) of the transmissibility as measured under the conditions of difference in pressure of 100 kPa and water temperature of 25 C at the length (L) of 200 mm to the square value (Pm<2>) of the average pore size (Pm) ([mu]m), is 3000 (m / day[mu]m<2>) or higher. The membrane can be produced by a method comprising the step of subjecting a stretched vinylidene fluoride resin hollow fiber porous membrane to a relaxation process comprising at least two stages in a non-wet atmosphere.

Description

technical field [0001] The present invention relates to a hollow-fiber porous membrane made of a vinylidene fluoride resin (a hollow-fiber porous membrane) excellent in (filtrated) water treatment performance, and a method for producing the same. Background technique [0002] Vinylidene fluoride-based resins are excellent in weather resistance, chemical resistance, and heat resistance, so their application to porous membranes for separation is being studied. In the case of (filtered) water treatment, especially drinking water production or sewage treatment, hollow fiber porous membranes that are easy to increase the membrane area per unit volume of filtration devices are often used, including their manufacturing methods. Many schemes have been proposed (for example, patent documents 1 to 3). [0003] In addition, the present inventors have also found that a vinylidene fluoride resin having a specific molecular weight characteristic is melt-extruded together with a plasticiz...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B01D71/34D01D5/247B01D69/08D01F6/12
CPCB01D67/0027B01D67/0086B01D69/02B01D69/08B01D71/34B01D2313/24B01D2323/12B01D2323/20C02F1/444D01D5/247D01F6/12
Inventor 高桥健夫多田靖浩铃木贤一日野雅之水野斌也
Owner KUREHA KAGAKU KOGYO KK
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