Polyvinyl alcohol formaldehyde adhesive and processing method thereof

Abstract

The invention discloses a polyvinyl alcohol formaldehyde adhesive, which is composed of the following components in parts by weight: 25 to 30 parts of polyvinyl alcohol, 3 to 5 parts of formaldehyde, 2 to 4 parts of urea, 5 to 8 parts of starch, 2 to 3 parts of methanol, 100 to 150 parts of water, a certain amount of hydrochloric acid, and a certain amount of sodium hydroxide. The adhesive is prepared by the following steps: step one, weighing polyvinyl alcohol, starch, and water according to the formula mentioned above, adding polyvinyl alcohol, starch, and water into a reactor, starting a stirring device, and heating to a temperature of 95 to 100 DEG C so as to completely dissolve polyvinyl alcohol; step two, reducing the temperature in the reactor to 80-85 DEG C, allowing the reactor to stand still for 15 minutes, and then adjusting the pH in the reactor to 2-3 by hydrochloric acid; step three, slowly dropwise adding formaldehyde into the reactor, and carrying out reactions for 1.5 to 2 hours at a constant temperature; step four, adding urea into the reactor, and keeping on reactions for 0.5 hour; and step five, adding methanol into the reactor, keeping on stirring for 0.5 hour, cooling to a temperature of 60 DEG C, dropwise adding sodium hydroxide, adjusting the pH to a neutral zone, cooling to the room temperature, and discharging to obtain a finished product. The prepared polyvinyl alcohol formaldehyde adhesive has the advantages of large viscosity and good initial adhesion, and contains little free formaldehyde.

Description

technical field [0001] The invention relates to a polyvinyl alcohol formaldehyde adhesive and a processing method thereof, which are applied in the technical field of adhesive processing. Background technique [0002] Adhesives are indispensable and important materials for the development of modern industry and the improvement of human living standards. They play an important role in modern economy, national defense and modern science and technology. Polyvinyl alcohol formaldehyde is an adhesive developed earlier. Due to its main raw material polyethylene Alcohol and starch are relatively low in cost and are widely used in the market, but the initial viscosity and stability of polyvinyl alcohol formaldehyde adhesives prepared by traditional methods on the market are poor, resulting in a narrower application range of the adhesive, and free formaldehyde in the adhesive The content is high and has certain hazards. Contents of the invention [0003] In order to solve the abov...

AI Technical Summary

Problems solved by technology

[0002] Adhesives are indispensable and important materials for the development of modern industry and the improvement of human living standards. They play an important role in modern economy, national defense and modern technology. Polyvinyl alcohol formaldehyde is an adhesive developed earlier. Because of its main raw material polyethylene Alcohol and starch are relatively low in cost and are widely used in the market. However, the initial viscosity and stability of polyvinyl alcohol formaldehyde adhesives prepared by traditional methods on the market are poor, resulting in a narrower application range of the adhesive and free formaldehyde in the adhesive. The content is high and has certain hazards