Film casting solution of PVDF hollow fiber ultrafiltration film as well as spinning mechanism and production method

A technology of ultrafiltration membrane and membrane casting liquid, which is applied in the field of polymer membrane preparation, and can solve the problems of loose material bonding, membrane layer falling off, and separation layer affecting separation performance, etc.

Pending Publication Date: 2020-11-13
浙江易膜新材料科技有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

In this method, the support tube is mostly polyester (PET) fiber, which contains oily spinning aids, and the coating is PVDF. The two different materials cannot be tightly bonded together, although the fracture strength of the composite film is greatly improved (> 100N) , but the PVDF membrane layer is easy to peel off or fall off from the braided tube, which reduces the service life of the membrane
There are many reasons why the combination between the PVDF membrane layer and the braided tube is not strong. One is that the porosity of the braided tube itself is not high, resulting in fewer spots for the spinning solution to penetrate into the fiber filaments inside the braided tube. The lower crochet tube is better than the braided tube; another reason is that the PVDF membrane prepared by the NIPS method is full of large holes or finger-shaped holes under the skin, resulting in a loose bond between the two materials.
At present, there are two methods to improve the bonding strength. One is to reduce the viscosity of the casting solution and improve the bonding force of the two through the casting solution infiltrating into the support tube. The disadvantage of this method is that the viscosity of the casting solution is low and the solid content is also low. The separation layer is easy to wear and tear during use to affect the separation performance; the other is to wash the support tube with alkali, remove the oil and make the support tube fluffy to improve the bonding force between the casting liquid and the support tube. This method is complicated and difficult to process on-line and synchronous spinning

Method used

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  • Film casting solution of PVDF hollow fiber ultrafiltration film as well as spinning mechanism and production method
  • Film casting solution of PVDF hollow fiber ultrafiltration film as well as spinning mechanism and production method

Examples

Experimental program
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Effect test

Embodiment 1

[0029] (1) Preparation of casting solution: Heat the temperature of the stirring tank to 110°C in advance, accurately weigh 1800.0 g of TEP, 90.0 g of DMAc, 600.0 g of PVDF (Sanaifu, FR904), 60.0 g of glycerin, 45.0g of Tween 80, 240.0g of PEG200, and 165.0g of PVP-k17, put the above raw materials into the stirring tank and stir for 10h, the stirring speed is set at 115 rpm, and the nitrogen is protected until the tank is uniformly dissolved; Reduce the stirring speed to 3 rev / min, stir and defoam at a low speed at 110°C for 8 hours for later use.

[0030] (2) Composite membrane spinning: use a dry-wet spinning machine to extrude and spin at a take-up speed of 20m / min, the inner support tube is a polyester crochet tube, and the outer diameter of the support tube is 1.2mm. The casting solution is evenly coated on the surface of the support tube through the spinneret, and enters the coagulation bath vertically. The dry spinning distance is less than 10cm. The coagulation bath is...

Embodiment 2

[0033] (1) Preparation of casting solution: Heat the temperature of the stirring tank to 140°C in advance, and accurately weigh 1650.0 g of TCT, 240.0 g of NMP, 300.0 g of PVDF (Sanaifu, FR915), and 400.0 g of PVDF ( Sanaifu, FR904), 60.0g of glycerin, 30.0g of Tween 80, 120.0g of PEG200, 120.0g of PEG400, 15.0g of PVP-k90, 15.0g of lithium chloride, add the above raw materials into the stirring tank and stir 12h, set the stirring speed to 130 rpm, and pass through nitrogen protection until the kettle is uniformly dissolved; then reduce the stirring speed to 4 rpm, and stir at a low speed of 140 ° C for 10 hours for degassing.

[0034] (2) Composite membrane spinning: use a dry-wet spinning machine to extrude and spin at a take-up speed of 22m / min. The inner support tube is a polyester crochet tube, and the outer diameter of the support tube is 1.9mm. The casting liquid is evenly coated on the surface of the support tube through the spinneret, and enters the coagulation bath v...

Embodiment 3

[0037] (1) Preparation of casting solution: Heat the temperature of the stirring tank to 120°C in advance, and accurately weigh 1950.0 g of GBL, 300.0 g of DMF, 540.0 g of PVDF (Sanaifu, FR909X), 60.0 g of glycerin, 30.0g of Tween 80, 180.0g of PEG400, 150.0g of PEG6000, 60.0g of PVP-k30, put the above raw materials into the stirring tank and stir for 10h, the stirring speed is set to 120 rpm, and the nitrogen gas is used to protect until the tank Dissolve evenly in the mixture; then reduce the stirring speed to 4 rpm, and stir at a low speed of 120°C for 12 hours for degassing.

[0038] (2) Composite membrane spinning: use a dry-wet spinning machine to extrude and spin at a take-up speed of 21m / min. The inner support tube is a polyester hook-woven tube, and the outer diameter of the support tube is 1.4mm. The casting liquid is evenly coated on the surface of the support tube through the spinneret, and enters the coagulation bath vertically. The dry spinning distance is less t...

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Abstract

The invention discloses a film casting solution of a PVDF hollow fiber ultrafiltration film as well as a spinning mechanism and a production method, and belongs to the technical field of polymer filmpreparation. The method comprises the following steps: 1) preparing the film casting solution, namely heating a stirring kettle to 110-150 DEG C in advance, adding PVDF, a poor solvent, a water-soluble good solvent and an additive into the stirring kettle, stirring and dissolving to form a uniform and transparent viscous solution, reducing the stirring speed, and defoaming the film casting solution for 8-12 hours in a heat preservation state; and 2) performing composite film spinning: spinning by using a dry-wet spinning machine by adopting a composite thermally induced phase separation methodto prepare the PVDF hollow fiber ultrafiltration film. The invention relates to the film casting solution of the PVDF hollow fiber ultrafiltration film as well as the spinning mechanism and the production method. Microstructures and crystal forms of surfaces and sections of film filaments are regulated and controlled through process parameter control, and the hollow fiber composite film which iscompact in surface layer, has spongy penetrating network pore structure in lower layer and is tightly combined with a supporting pipe is prepared.

Description

technical field [0001] The invention belongs to the technical field of polymer membrane preparation, and in particular relates to a casting liquid of a PVDF hollow fiber ultrafiltration membrane, a spinning mechanism and a production method thereof. Background technique [0002] As a common material for separation membranes, polyvinylidene fluoride (PVDF) is widely used in water supply engineering, industrial wastewater, pharmaceutical industry, food industry, energy industry and other fields. However, the strong hydrophobicity of PVDF membrane makes it easy to be polluted, which increases the operating cost of the membrane and limits its use. Phase inversion methods are mostly used to prepare PVDF membranes, which mainly include: non-solvent induced phase separation (NIPS), thermally induced phase separation (TIPS), composite thermally induced phase separation (C-TIPS), etc. [0003] The NIPS method is a common method for most membrane materials to make membranes. Usually ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B01D67/00B01D69/08B01D69/02B01D61/14
CPCB01D67/0011B01D67/0013B01D69/087B01D69/02B01D61/145
Inventor 马旭敏王炎锋叶麒计宇胥鸣高明富赵经纬丁国良
Owner 浙江易膜新材料科技有限公司
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