Patent ID: 7473300

Claim:
A moisture absorbent composition comprising: a thermoplastic resin selected from the group consisting of polyethylene, polypropylene, polyethylene terephthalate, polyvinyl chloride, ABS, polyamide, polystyrene, polyvinyl alcohol, polycarbonate, ethylene-methacrylate copolymer, and polyacetal; and a moisture absorbent having an equilibrium vapor pressure, kneaded into the thermoplastic resin, the moisture absorbent comprising of magnesium sulfate represented by the formula MgSO4.nH 2 O (0≦n≦3); wherein a surface of the moisture absorbent is coated with a fatty acid metal salt so that the moisture absorbent comes to have a secondary particle size of substantially 1 to 40 μm when dispersed in the thermoplastic resin, in case of that the thermoplastic resin is polyethylene, polypropylene, polyethylene terephthalate, or polyvinyl chloride, equilibrium humidity is raised/lowered by about RH 12% as specific gravity of the thermoplastic resin is increased/decreased by 0.01, and in case of that the thermoplastic resin is ABS, polyamide, polystyrene, polyvinyl alcohol, polycarbonate, ethylene-methacrylate copolymer, or polyacetal, equilibrium humidity is raised/lowered by about RH 3% as specific gravity of the thermoplastic resin is increased/decreased by 0.01.