| 摘要 |
PURPOSE:To improve adhesion to porous adherends, by blending microballoons obtd. from an org. matter with a polyurethane sealing material compsn. CONSTITUTION:A polyurethane sealing material compsn. contains 0.1-5wt.% microballoons having a true specific gravity of 0.01-0.1, obtd. from an org. matter. Examples of the microballoon are an isobutane foam of a copolymer of polyvinylidene chloride with acrylonitrile, a foam of a copolymer of methyl methacrylate with acrylonitrile, etc. The polyurethane sealing compsn. include one-component and two-component systems. The one-component system is obtd. by blending a prepolymer of polyurethane with a plasticizer, a filler, an anti- sagging agent, a colorant, a weathering stabilizer, a solvent, etc. In the two- component system, its first component is composed of the prepolymer and its second component is a hardener and formed by blending a polyol or a mixture thereof with a polyamine, with a catalyst, a plasticizer, a filler, an anti-sagging agent, a weathering stabilizer, a solvent, etc.
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