"KURARAY POVAL" is manufactured by the hydrolysis of polyvinyl acetate with caustic soda. In the 1950's, when Kuraray started mass production of PVA, vinyl acetate, the intermediate raw material of PVA, was produced from acetylene. However, after the 1960's, vinyl acetate started to be produced from ethylene, and currently this ethylene method is adopted in Okayama Plant, instead of former acetylene method.

1) Polymerization

Polymerization is a reaction that synthesized polyvinyl acetate (PVAc) by uniting many molecules of vinyl acetate monomer. The number of united VAc molecules represents degree of polymerization.
In this stage, VAc can be co-polymerized with other monomer, and accordingly the physical properties of PVA can be modified.
(Please refer to Special grades)

2) Saponification (Hydrolysis)

Saponification is a reaction that synthesizes PVA by replacing acetic acid radical of PVAc with hydroxyl radical. The percentage of hydroxyl radical in PVA against the total number with acetic acid radical is represented as degree of hydrolysis.
In order of higher degree of hydrolysis, it is called as completely hydrolyzed PVA, medium hydrolyzed PVA, partially hydrolyzed PVA.
(Please refer to the grade list)
The PVA's degree of hydrolysis affects its water solubility and the water resistance of film.