A kind of polyvinyl butyral synthesis method based on homogeneous and heterogeneous two-stage reaction

A technology of polyvinyl butyral and a synthesis method, applied in the field of resin synthesis, can solve problems such as the influence of acetal degree, and achieve the effects of improving lipophilicity, reducing load, reducing load and transmission resistance

Active Publication Date: 2018-04-17
TSINGHUA UNIV
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  • Description
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AI Technical Summary

Problems solved by technology

Once the equipment or operating conditions cannot meet the requirements, large PVB particles wrapped with PVA will easily form in the system, making it difficult for butyraldehyde to penetrate further into the solid interior to complete the subsequent reaction under the influence of internal diffusion resistance, thus having a serious impact on the final degree of acetalization

Method used

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Effect test

preparation example Construction

[0017] A polyvinyl butyral synthetic method based on homogeneous and heterogeneous two-stage reactions, comprising the steps:

[0018] (1) prepare PVA aqueous solution, add part n-butyraldehyde, and add HCl solution, fully mix, react under homogeneous condition, obtain homogeneous solution;

[0019] (2) Dispersing the remaining n-butyraldehyde in the homogeneous solution described in step (1) in the form of droplets at one time, reacting under heterogeneous conditions, then heating up to continue the reaction until the reaction is completed, to obtain PVB slurry;

[0020] (3) Perform conventional filtration, washing, and drying on the PVB slurry to obtain PVB products.

[0021] Sampling and analysis of its degree of acetalization, hydroxyl value and viscosity of 5% ethanol solution.

Embodiment 1

[0023] Reaction conditions: the mass fraction of PVA in the PVA aqueous solution is 5%; add a small amount of n-butyraldehyde and HCl solution to form a homogeneous mixed solution, wherein the mass ratio of n-butyraldehyde to PVA is 0.06:1, and the mass ratio of HCl to PVA is 0.15 : 1, the massfraction of HCl in the HCl solution is 10%; The reaction temperature of homogeneous reaction is 35 ℃, and the time is 50min; The mass ratio of the initial PVA in the solution is 0.65:1; the reaction is continued for 3.0 hours at a reaction temperature of 65°C; and finally the temperature is lowered to 35°C.

[0024] Reaction results: the acetalization degree of the product PVB is 79.1%, the hydroxyl value is 18.3%, and the viscosity of 5% PVB ethanol solution is 89 mPa·s.

Embodiment 2

[0026] Reaction conditions: the mass fraction of PVA in the PVA aqueous solution is 15%; add a small amount of n-butyraldehyde and HCl solution to form a homogeneous mixed solution, wherein the mass ratio of n-butyraldehyde to PVA is 0.10:1, and the mass ratio of HCl to PVA is 0.10 : 1; the mass fraction of HCl in the HCl solution is 10.0%; the reaction temperature of the homogeneous reaction is 30 ℃, and the time is 90min; after the remaining n-butyraldehyde is added, the heterogeneous reaction is carried out for 0.5h. The mass ratio of the initial PVA in the solution is 0.64:1; then continue the reaction at a reaction temperature of 65°C for 2.0h; finally cool down to 30°C.

[0027] Reaction result: the degree of acetalization of the product PVB is 78.6%, the hydroxyl value is 19.3%, and the viscosity of 5% PVB ethanol solution is 80mPa·s.

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Abstract

The invention relates to a polyvinyl butyral (PVB) synthesis method based on homogeneous and heterogeneous two-stage reaction. The method includes: firstly fully mixing a polyvinyl alcohol water solution, a small amount of n-butylaldehyde and an HCl solution to carry out homogeneous reaction, thus obtaining a homogeneous solution; and then dispersing the rest n-butylaldehyde in a droplet form into the homogeneous solution in one time to obtain a heterogeneous reaction system, carrying out heterogeneous reaction, then raising the temperature for further reaction till the end of reaction, and carrying out filtering, washing and drying, thus obtaining a PVB product. The method provided by the invention firstly guarantees that part of acetalization finishes under a homogeneous condition, the PVA molecule hydroxyl density is reduced, the n-butylaldehyde adding amount is controlled to make the system be close to the critical state of precipitating solid PVB after early stage reaction, and on the basis the rest n-butylaldehyde is added for rapid precipitation of PVB solid, thus obtaining micron-sized porous particles. The load and transfer resistance of heterogeneous reaction are effectively reduced, high acetalization degree PVB synthesis is realized, and at the same time the n-butylaldehyde utilization is greatly improved.

Description

technical field [0001] The invention belongs to the technical field of resin synthesis, in particular to a polyvinyl butyral synthesis method based on homogeneous and heterogeneous two-stage reactions. Background technique [0002] As a polymer resin, polyvinyl butyral (PVB) is mainly used in the automobile and construction industries. It can be used as an intermediate adhesive layer for automobile windshields, bulletproof glass, and adhesives for architectural coatings. It is a photovoltaic substrate for solar cells. It is an important material in the sealing material and LED substrate manufacturing process. [0003] High-quality PVB requires an acetalization degree of more than 78%, that is, the chain segment with acetal groups accounts for more than 78% of the mass fraction of the entire molecule, and the hydroxyl group is evenly distributed to meet the light transmittance index of the adhesive layer, especially For intermediate consumables made of LED substrates, the re...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C08F8/28C08F16/06
CPCC08F8/28C08F16/06
Inventor 王凯林茜妍骆广生
Owner TSINGHUA UNIV
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