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Food-grade polyvinylidene fluoride membrane and manufacturing method thereof

A technology of polyvinylidene fluoride film and polyvinylidene fluoride, which is applied in the field of food-grade polyvinylidene fluoride film and its manufacturing, to achieve the effects of no additional pollution, high throughput, and less leached matter

Active Publication Date: 2018-06-29
ZHEJIANG CHANGXING CREFLUX MEMBRANE TECH CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

So far, there are few reports on food-grade PVDF drying membranes with less extractables

Method used

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  • Food-grade polyvinylidene fluoride membrane and manufacturing method thereof
  • Food-grade polyvinylidene fluoride membrane and manufacturing method thereof
  • Food-grade polyvinylidene fluoride membrane and manufacturing method thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0037] A method for manufacturing a food-grade polyvinylidene fluoride film, comprising the following steps:

[0038] 1) Prepare a homogeneous polyvinylidene fluoride solution: 25 parts by weight of polyvinylidene fluoride PVDF (Blue Sky 2212) and 2 parts by weight of food-grade hydrophilic second polymer sulfonated polysulfone ([η]=0.6) Prepare a uniform and stable polyvinylidene fluoride solution with 73 parts by weight of organic solvent N,N-dimethylacetamide, and keep the temperature at 90°C;

[0039]2) Mold forming: while maintaining the uniform distribution of the four strands of reinforcing fiber filaments, send the degassed homogeneous solution at 90°C to the forming hollow mold, and at the same time, the internal liquid formed with water is sprayed from the double annular nozzle;

[0040] 3) Pass the molded product obtained in step 2) through a 20cm air gap, and immerse it in a coagulation water bath formed by 40°C water to complete the formation and fixation of the m...

Embodiment 2

[0070] Except step 5) replacing 5 parts by weight of NaCl in the brine bath with 2.5 parts by weight of NaCl, the hollow fiber membrane was produced according to the same formula and process as in Example 1.

[0071] The pure water flux of the membrane before drying was 630 LMH, the pure water flux after drying was 496 LMH, and the water content of the membrane after drying was 0.9% by weight. The films were tested for leaching substances, and the results are shown in Table 1. The further reduction of the concentration of the pore retaining agent sodium chloride further reduces the water content and pure water flux of the dried membrane. The extractables are similar to Example 1, both of which are hollow membranes with a very low amount of extractables.

Embodiment 3

[0073] The hollow fiber membrane was manufactured according to the same formula and process as in Example 1, except that 2 parts by weight of sulfonated polysulfone in the membrane-making stock solution was replaced by 2 parts by weight of cellulose acetate (CA 398-10).

[0074] The pure water flux of the membrane before drying was 550 LMH, the pure water flux after drying was 488 LMH, and the water content of the membrane after drying was 1.7% by weight. The films were tested for leaching substances, and the results are shown in Table 1. Since no water-soluble macromolecular PVP, PEG, surfactant and other organic substances are added to the stock solution, and no organic pore retaining agent such as glycerin is used in the post-treatment drying process, the absorbance of the film is below 0.04. The content of extractables is very small.

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Abstract

The invention relates to the technical field of water treatment, and especially relates to and discloses a food-grade polyvinylidene fluoride membrane. The dissolved matter content included in the liquid obtained by digesting the membrane for 24 hours in ultra-pure water heated to 80 DEG C is less than or equal to 1.0 mg / m<2>, and the mass water content of the membrane is less than or equal to 10%. The invention further discloses a food-grade polyvinylidene fluoride membrane: (1) preparing uniform polyvinylidene fluoride liquid; (2) mold forming; (3) entering solidification water bath throughair gap and then performing the water bath solidification forming; (4) performing water bath extraction to remove the solvent; (5) performing brine bath to enable the membrane to absorb pinch of saltas the membrane hole maintaining agent; and (6) drying. The food-grade polyvinylidene fluoride membrane disclosed by the invention is less in dissolved matter, low in water content, capable of maintaining higher flux, high in strength, stable in structure and suitable for the food application; and the manufacturing method is simple and controllable and free from additional pollution.

Description

technical field [0001] The invention relates to the technical field of water treatment, in particular to a food-grade polyvinylidene fluoride film and a manufacturing method thereof. Background technique [0002] Polyvinylidene fluoride (PVDF) is a semi-crystalline polymer with good mechanical properties, weather resistance and chemical stability. It is widely used in water treatment, aerospace, food and beverage, biomedicine and other fields, and has become the mainstream ultra- , Microfiltration membrane products. The research on the preparation of high-performance PVDF membranes based on the phase inversion method has been a research hotspot in the field of membrane separation for many years, and has attracted extensive attention from international membrane researchers and the industry. [0003] In the process of PVDF phase inversion film-making process, it is often necessary to add macromolecular pore-forming agents, such as polyvinylpyrrolidone (PVP) and polyethylene g...

Claims

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Application Information

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IPC IPC(8): B01D67/00B01D69/02B01D71/34
CPCB01D67/0013B01D69/02B01D71/34B01D2325/36
Inventor 沈红梅张星星包进锋李芸芳杨永红周凌跃张多鹏
Owner ZHEJIANG CHANGXING CREFLUX MEMBRANE TECH CO LTD
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