Preparation of polyvinyl alcohol and its acetalization reaction- tianyuan polymer

Polyvinyl butyral resin manufacturer's small editor today to introduce to you about the preparation of polyvinyl alcohol and its acetalization reaction related to it, in addition to the preparation of adhesives or coatings, you can also prepare other materials through polyvinyl acetal reaction? Polyvinyl alcohol is a collective term for condensation products with various aldehydes. The main varieties are polyethylene formaldehyde and butyraldehyde. It was manufactured in Canada in 1930 by the Shawingigen Chemical Company. Common production techniques include the homogeneous one-step method and the heterogeneous two-step method. The one-step method usually uses alcohol as a solvent.

The polyvinyl alcohol acetalization reaction is carried out under the catalytic action of strong acids, and the hydrolysis and contraction of crude polyvinyl acetate with aldehydes is carried out. The reaction temperature is 65 ~ 75 ° C, although the process is short, but it consumes solvents. The two-step method is to hydrolyze polyvinyl acetate to polyvinyl alcohol, which is then condensed with the corresponding aldehyde. Easily soluble in formic acid, acetic acid and phenol. The relative density is 1.22 to 1.23. It has the advantages of high strength, high softening point (140~ 150 °C), heat resistance, solvent resistance, wear resistance, flexibility and dielectric properties. In addition to being widely used in polyvinyl alcohol fibers, it is also used as a coating for insulating enameled wires and for metal containers. Mixed with thermoset phenolic resin, it can be made into heat-resistant, waterproof, oil-resistant, non-melting, insoluble high-strength insulation coatings, as well as excellent properties, suitable for bonding between aluminum alloys, steel, wood, rubber, widely used in the aviation industry.

(1) Antifreeze In order to prevent the glue from freezing, in winter, ethylene glycol of 0.2% of the total amount of glue can be added as an antifreeze agent.

(2) The crosslinking agent (curing agent) can be crosslinked with polyvinyl alcohol, so that the polyvinyl alcohol is no longer dissolved, improving the water resistance. Commonly used are inorganic salts, inorganic acids, a variety of organic acids and so on. Polyvinyl alcohol can also be cured by heating (160~ 200 °C).

(3) Preservatives in summer, in order to prevent the deterioration of the glue, 0.2% to 0.3% of formaldehyde can be added to the total amount of the glue as a preservative.

(4) Plasticizers can be added to increase the flexibility of the film, such as glycerol, polyethylene glycol, sorbitol, polyamide, urea derivatives, etc.

(5) In order to improve the bonding speed and reduce the cost of fillers, starch, rosin, gelatin, clay, titanium dioxide and other fillers can be added.

(6) The main agent polyvinyl alcohol or polyvinyl alcohol acetal (commonly used in industry is polyvinyl alcohol acetal and acetal) as a binder.

Polyvinyl butyral resin manufacturers of the small editor will introduce you to here, have questions can call the small editor I!

Article source: https://www.tanyunpvb.cn/news/836.html