PURPOSE: To improve the packaging film characteristics such as water solubility, film formability and strength by copolymerizing N-vinylacetamide and the vinyl monomers represented by predetermined general formulas to form a water- soluble thermoplastic packaging film.
CONSTITUTION: The packaging film is of a water-soluble thermoplastic copolymer obtained by copolymerizing N-vinylacetamide in an amount of 35-95wt.% and the vinyl monomers represented by the general formulas (I)-(VII), e.g. vinyl acetate in an amount of 5-65wt.%. In the formulas, R1, R3, R6, and R7-R10 are lower alkyl groups having 1-4 carbon atoms, R2, R4, R5 and R11 are hydrogen or methyl group, 11 is an inreger of 1-100 and R6, R8 and R9 may be hydrogen. The mix proportion of the vinyl monomer is determined by the number of carbon atoms contained in substituents R1-R11 in the general formula I-VII. In the general formula I, for example, it is preferable to contain the vinyl monomer in an amount of 20-60wt.% when R1 has 1-2 carbon atoms.
KAMATA HIROTOSHI
HOSODA KIICHI
AIZAWA TOSHIYUKI
NAKAMURA HITOSHI
