Thermoplastic sulfonic copolymerized polyvinyl alcohol resin with low melting point and high thermal stability as well as preparation method and application of thermoplastic sulfonic copolymerized polyvinyl alcohol resin

The invention provides thermoplastic sulfonic copolymerized polyvinyl alcohol resin with low melting point and high thermal stability as well as a preparation method and application thereof. The water-based adhesive comprises the following components: sulfonyl copolymerized polyvinyl alcohol and a thermoplastic agent, the sulfonyl copolymerized polyvinyl alcohol is one or a mixture of more of vinyl alcohol-vinyl acetate-sulfonyl unsaturated hydrocarbon monomer terpolymers with the polymerization degree of 500-3500, the unit content of vinyl alcohol of 94-99.7 mol%, the total content of vinyl acetate and sulfonyl units of 0.3-6 mol% and the mass fraction of sulfur element of 0.1-4%; the thermoplastic agent is at least one of polyol, polyether polyol or polyol ester; the mass ratio of the sulfonic copolymerized polyvinyl alcohol to the thermoplastic agent is (60-95): (5-40). The melting point of the prepared thermoplastic sulfonic copolymerized polyvinyl alcohol resin is 120-180 DEG C, and the thermal decomposi