Polyvinyl acetal resin for coating and ink, and coating and ink compositions
It is an object of the invention to provide a polyvinyl acetal resin for lacquer and ink, which can suppress the occurrence of coloring and foul odor of the polyvinyl acetal resin itself even when no antioxidant is used at all therein, and a lacquer and ink composition which has excellent color and the high stability of viscosity in storing it for long periods. The invention provides a polyvinyl acetal resin for lacquer and ink synthesized by acetalization reactio of polyvinyl alcohol and an aldehyde, wherein a polymerization degree is 100 to 3,000, a proportion of a residual acetyl group is 25 mol % or less and a proportion of a residual hydroxyl group is 17 to 35 mol %; a content of the residual aldehyde is 100 ppm or less, a content of residual butyric acid is 100 ppm or less, a content of residual 2-ethyl-2-hexenal is 100 ppm, and a content of a residual acid catalyst is 300 ppm or less, and no antioxidant is remained at all therein.
1. A method for suppressing the occurrence of coloring and a foul odor of the polyvinyl acetal resin synthesized by acetalization reaction of polyvinyl alcohol and an aldehyde without using an antioxidant,
which comprises reducing a content of the residual aldehyde to be 100 ppm or less, a content of residual butyric acid to be 100 ppm or less, a content of residual 2-ethyl-2-hexanal to be 100 ppm, and a content of a residual acid catalyst to be 300 ppm or less.
2. A method for suppressing the occurrence of coloring and a foul odor of the polyvinyl acetal resin synthesized by acetalization reaction of polyvinyl alcohol and an aldehyde without using an antioxidant,
which comprises reducing a content of the residual aldehyde to be 100 ppm or less, a content of the residual acetic to be 100 ppm or less, a content of residual 2-methyl-2-pentenal to be 100 ppm, and a content of a dual acid catalyst to be 300 ppm or less.
3. A method for suppressing the occurrence of bring and a foul odor of the polyvinyl acetal resin synthesized by acetalization reaction of polyvinyl alcohol and an aldehyde without using an antioxidant,
which comprises reducing a content of the residual aldehyde to be 100 ppm or less, a content of residual butyric acid to be 100 or less, a content of residual acetic acid to be 100 ppm or less, a content of residual 2-ethyl-2-hexenal to be 100 ppm, a content of residual 2-methyl-2-pentenal to be 100 ppm, an a content of a residual acidic catalyst to be 300 ppm or less.