| 摘要 |
PURPOSE:To produce a polywood having excellent surface smoothness, by coating a veneer with a water-based adhesive added with a latent hardener and a thermally expanable microcapsule containing a substance having low boiling point and heating the coated veneer above a specific temperature under pressure. CONSTITUTION:(A) A water-based adhesive such as urea resin adhesive, melamine resin adhesive, etc., optionally added with an extender and water is mixed with (B) thermally expandable microcapsules (made of e.g. vinylidene chloride copolymer) containing a substance having low boiling point (e.g. propane, butane, etc.) and (C) a latent hardener which is neutral at normal temperature and turns acidic at the heat-curing temperature of the component A to exhibit hardening action (e.g. inorganic acid salt or organic acid salt of amines, dimethyl oxalate, Na salt or Ba salt of ethyl sulfate, etc.). The amounts of the components B and C are 0.1-10(wt)% and 1-20% based on the solid content of the component A, respectively. A veneer is coated with the above adhesive mixture and heated under pressure above the foaming temperature of the component B to obtain a plywood.
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