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| PDF : |  12060277.pdf |
| title(En) : | Studies on the Powdered-Dry Bonding Process in the Manufacture of Plywood. IV. On the Exothermic Behaviours in the Initial Reaction of Urea-Formaldehyde and Those of Urea-Resin Adhesives |
| author(En) : | Atsuo Tanaka, Kiyomine Takashima |
| information : | Mokuzai Gakkaishi 12(6), 277-281 (1966) |
| assort : | Original Article |
| summary(En) : | In a previous paper we studied the exothermic behaviour of urea-resin adhesive in the curing process after mixing ammonium chloride hardner. The first results of the investigations presented in this report are the exothermic behaviours at the addition and condensation reaction that take place between urea and formaldehyde. The next results of those are the effects of the initial temperature of resins, the solid content and the condensation degree of urea-resin adhesives on the exothermic behaviours. The results obtained are as follows; 1) Both the addition and the condensation reaction at the urea and formaldehyde reaction are exothermic. The reactant temperature is affected by the reaction rate. 2) As the initial temperature of the urea-resin adhesives increases, the period of the second exothermic stage shortens and the increasing ratio of the reactant temperature at the final exothermic stage gets large. 3) The higher the solid content of the urea-resin adhesives is, the larger the increasing ratio mentioned above is. 4) The smaller the condensation degree of the urea-resin adhesives is, the lager the increasing ratio mentioned above is. 5) It seems that the exothermic behaviour of the urea-resin adhesives is affected by the rate of the curing reaction and the total calorific value, but we can not presume the change of the reactant temperature by the gelation time alone. |