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Study on the Curing Characteristics and Properties of Low Molar Ratio Urea-Formaldehyde Resin

Author: DongYaoHui
Tutor: LiJianZhang
School: Beijing Forestry University
Course: Wood Science and Technology
Keywords: Low molar ratio urea-formaldehyde resin Melamine modified urea-formaldehyde resin Curing agent Curing characteristics Plywood Bonding strength Formaldehyde emission
CLC: TQ433.431
Type: Master's thesis
Year: 2011
Downloads: 227
Quote: 1
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Abstract


Urea-formaldehyde resin is a cheap, synthetic performance adhesives, widely used in wood-based panels, especially the plywood industry. But due to its molecular structure, synthesis process and other reasons, urea-formaldehyde resin widespread with resistance to boiling water resistance, resistance to aging performance difference and the storage period is short and other shortcomings, especially the the the ordinary urea-aldehyde resin free formaldehyde content is high and glued products formaldehyde emission, pollution environment, affect people's physical and mental health. Therefore, the excellent performance of research and development, low content of free formaldehyde modified low molar ratio of urea formaldehyde resin become an important issue in the current, and important social and economic value. In order to improve the environmental performance of the urea-formaldehyde resin, this paper studied the low performance of the molar ratio of urea formaldehyde resin and modified low molar ratio urea-formaldehyde resin curing characteristics and plywood. Through the preparation of different low molar ratio of urea formaldehyde resin to explore the molar ratio of urea formaldehyde resin reasonable; through the amount of different curing agents and its add urea-formaldehyde resin curing time, curing of the pH and curing thermal analysis reveals low molar ratio of urea formaldehyde resin curing characteristics analysis of melamine modified urea formaldehyde resin; through different melamine amount of modified urea-formaldehyde resin structure and curing characteristics optimized synthesis process and performance. The main conclusions are as follows: (1) formaldehyde and urea molar ratio of urea-formaldehyde resin having a good curing characteristics and plywood performance 1.1; and 1% of ammonium chloride as a curing agent, plywood has better in this thesis overall performance. (2) a single-component curing agent is ammonium chloride, ammonium sulfate was 1% urea-formaldehyde resin having a good curing characteristics; complex-type curing agent such as ammonium dihydrogen phosphate / diammonium phosphate can also be used as a preferred The curing agents play a curing effect. (3) the amount of melamine added to 9 percent when the modified urea-formaldehyde resin has a good overall performance; experiments of this study, along with melamine Add to increase the amount of modified urea-formaldehyde resin curing time was significantly longer pot life and The storage period was significantly shorter; melamine added in an amount to improve the curing reaction temperature is gradually increased, and the curing reaction intensity gradually weakened. (4) With improvement of melamine added in an amount, a modified urea formaldehyde resin structure hydroxymethyl gradually generate a methylene group, the degree of crosslinking between molecules increases; With improvement of melamine added in an amount, a modified urea-formaldehyde resin and a resin cured diffraction peaks gradually smooth, significantly reduced the degree of crystallinity of the modified urea-formaldehyde resin cured before curing.

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CLC: > Industrial Technology > Chemical Industry > Adhesive Industry > Synthetic adhesive > Rubber, resin as raw material adhesive > Synthetic resin adhesive of the raw materials > Phenol-formaldehyde , urea- aldehyde adhesive
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