| 摘要 |
PROBLEM TO BE SOLVED: To obtain a melamine resin composition which gives lightweight molded items having a decreased dispersion of specific gravity and having uniform qualities and a good luster by incorporating glass microballoons having a specified compression strength into a melamine resin. SOLUTION: Except glass microballoons, ingredients of this composition are not specifically limited. For example, the composition contains 65-75 wt.% melamine resin, 25-30 wt.% pulp and 3-5 wt.% inorganic gypsum as fillers, 0.1-0.5 wt.% phthalic anhydride as a curing agent, and 0.5 wt.% zinc stearate and 0.05-0.1 wt.% stearamide as lubricants. The glass microballoons have a compression strength of 100-300 kgf/cm2, an average particle size of 30-60μm, and an apparent specific gravity of 0.3-0.4, and the content in the composition is 5-20 wt.%. The composition is charged into a metal mold and subjected to straight hydraulic molding at a mold temperature of 155 deg.C for 50 sec, thus giving the objective molded item.
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