Study on Modification of Polyvinyl Acetate Copolymer Adhesive (I)

Polyvinyl acetate (PVAc) is one of the main adhesives. It was industrialized in Germany in 1930. It has the advantages of high bonding strength, fast curing speed, simple production process, and easy use. It can be used to bond wood. Fiber, leather, paper, and especially wood furniture are the most used. The early use of PVAc homo-emulsion was generally based on the use of polyvinyl alcohol with a degree of alcoholysis of about 80% as a protective colloid, and peroxide as an initiator. The solids content was about 50%. However, this single-component polyvinyl acetate emulsion has many disadvantages, such as poor water resistance and poor heat resistance, and its bonding strength will be greatly reduced under moist heat conditions; its film-forming creep resistance is poor over a long period of time. Under the action of the load, the adhesive layer will slide, and its moisture resistance, cold resistance, and mechanical stability will also deteriorate. With the development of science and technology and economy, the improvement of people's living standards and the higher requirements for products have obviously affected the application of products. For example, high-grade furniture requires adhesives with high resistance to heat, moisture and water, and no harmful gases are released. By modifying the polyvinyl acetate glue solution, its shortcomings can be overcome. In recent years, the modification of polyvinyl acetate, especially copolymerization modification, has been a focus and hotspot at home and abroad.

In this paper, under the conditions of industrial alcohol as solvent, the reaction conditions, influencing factors, formulas, etc. of vinyl acetate copolymerization were studied in detail, and a high-performance glue solution with non-toxic, quick-drying, high bonding strength, and good water resistance was prepared. .

A raw material and formulation (see Table 1 2)


The solubility of ternary copolymerization in alcohol is not very good, and an appropriate amount of non-toxic solvent such as acetone can be added, which can significantly improve the dissolution performance.

Preparation

Two-thirds of the vinyl acetate and other reactive monomers were added to the beer bottle with a stirring and condensing resuscitation device. Half of the initiator was added, all the alcohol was added, and the mixture was stirred and warmed to reflux for 2 hours. The mixture of the remaining raw materials was added dropwise at the reflux temperature, and the addition was completed in 2 hours, followed by reaction at the reflux temperature for 3 to 4 hours. Monomer content and viscosity meet the requirements. Slowly add appropriate amount of sodium sulfite, cool down about 40 degrees, add plasticizer, and mix evenly.

Performance Testing

The water resistance was obtained by uniformly applying rubber to two solid three-layer plywood and pressing them together until they were solidified. The water resistance was immersed in 60% water and the number of days when the glue was opened was measured.

(to be continued)

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