Production Process of Polyvinyl Butyral Resin

Polyvinyl Butyral Resin PVB Precipitation Method PVB One-step Method PVB Dissolution Method PVB For Laminated Glass PVB For Electrical Materials PVB Powder

The full name of PVB is polyvinyl butyral, or PVB resin for short. It contains a lot of hydroxyl (OH) groups, which can produce bridging reactions with some thermosetting resins to improve chemical resistance and coating film hardness. PVB molecules contain long branched chains and have good flexibility, excellent transparency, strong adhesion, good light resistance, heat resistance, cold resistance, water resistance, film-forming properties, solubility, miscibility, high tensile strength and impact resistance, etc. It is widely used in the fields of manufacturing laminated safety glass, coatings, adhesives, ceramic film decals, vacuum aluminum foil paper, electrical materials, fiberglass products, fabric treatment agents and engineering plastics. It is a synthetic resin material with broad development and utilization prospects.

 

There are three main synthesis methods for producing PVB in the industry: one-step method, dissolution method and precipitation method. The following will introduce these three process methods and their advantages and disadvantages in the production process one by one.

 

The one-step method refers to a generation process in which the hydrolysis of polyvinyl acetate (PVAC) and the acetal reaction of the generated PVB are carried out simultaneously. It is represented by the production process of Solutia Company (the chemical division of Monsanto Company was split to form Solutia Company, which has now been acquired by Eastman Company). Vinyl acetate is bulk polymerized to form a methanol solution of polyvinyl acetate, and HCI is added for alcoholysis. The PVA generated by alcoholysis is suspended in a mixed solvent of ethanol and ethyl acetate, and butyraldehyde and HCI are added for acetal reaction. At the reflux temperature, react for 8 to 10 hours. As the reaction proceeds, PVA is completely dissolved and a uniform PVB solution is finally formed. Then add alkali to adjust the pH to 6. After reaching the specified acetal rate, it precipitates in water. After washing, neutralizing and drying, the finished PVB product can be obtained.

 

The dissolution method is to make PVA into a methanol suspension, add HCI and butyraldehyde to perform a condensation reaction. As the reaction proceeds, PVA gradually dissolves to form a uniform solution. After reaching the specified acetal ratio, it precipitates in water. After washing, neutralizing and drying, the finished PVB product can be obtained. The acetal rate of the PVB resin produced by this method can reach more than 86%, and the condensation distribution is uniform.

 

The precipitation method requires first dissolving PVA in water (85-90°C), then filtering the solution, pressing it into an acetal kettle, adding hydrochloric acid and butyraldehyde, and adding butyraldehyde in two batches to start homogeneous condensation. When the reaction reaches a certain level, PVB particles are precipitated from the solution and suspended in the mother liquor, which is a heterogeneous condensation reaction. When the condensation is completed, the material is put into a water washing kettle, washed with water, and alkali is added for stabilization, then filtered and dried to obtain powdered PVB.

 

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