Abstract: Provided is an additive for a thermoplastic resin prepared by mixing tannin with a coupling agent, and the above additive inhibits the thermoplastic resin from being reduced in a molecular weight in heating and melting and achieves heat stabilization of the thermoplastic resin. Accordingly, it becomes possible to recycle the molded articles.

Abstract: The present invention provides a resin additive obtained by subjecting inorganic particles to surface treatment with catechin, a resin additive obtained by subjecting inorganic particles to surface treatment with catechin and further subjecting them to surface treatment with a coupling agent or a resin additive obtained by subjecting inorganic particles to surface treatment with catechin and then subjecting them to surface treatment with a phenone compound or saccharides, followed by further subjecting them to surface treatment with a coupling agent. These resin additives have the effect to inhibit a reduction in the molecular weight of a thermoplastic resin in heating and melting or inhibit a reduction not only in the molecular weight but also the IZOT impact strength.

Abstract: Tannin obtained by dehydrating it by heating up to 70 to 230° C. to subject it to polycondensation is used as a resin additive.

Abstract: The present invention provides a resin additive obtained by subjecting inorganic particles of silica or alumina to surface treatment with tannic acid and further subjecting them to surface treatment with a coupling agent, or subjecting inorganic particles to surface treatment with tannic acid and then subjecting them to surface treatment with a phenone compound or saccharides, followed by further subjecting them to surface treatment with a coupling agent. The above resin additive has an effect to provide a thermoplastic resin with heat stability in heating and melting the resin and prevent a reduction in the IZOT impact strength.