C - Chemistry – Metallurgy – 08 – G
Patent
C - Chemistry, Metallurgy
08
G
402/90
C08G 12/12 (2006.01) C08G 12/40 (2006.01)
Patent
CA 1192339
- 1 - SPECIFICATION Title of the Invention Process for Producing Crosslinked Urea-Formaldehyde Polymer Particles Abstract Disclosed is a process for producing fine particles of crosslinked urea-formaldehyde polymer which comprises the steps of synthesizing a precondensate of urea and formaldehyde, allowing the precondensate to react by the addition of an aqueous solution of an acid catalyst, and then neutralizing the reaction mixture, characterized in that the filtrate obtained in the filtration step for separating the polymer particles is recycled to the reaction system at the step of synthesizing a precondensate - 2 - of urea and formaldehyde and/or the step of allowing the precondensate to react by the addition of an aqueous solution of an acid catalyst and in that the precondensate is obtained by reacting 1 mole of urea with 1.4 to 1.9 moles of formaldehyde at a pH of 6 to 10 and a temperature of 10 to 95°C. While such fine particles of crosslinked urea- formaldehyde polymer are useful as a filler for improving certain properties (such as opacity and the like) of paper, disposal of the filtrate resulting from the filtration step for separating the polymer particles has been a serious problem. The disclosed process is carried out in a closed system by recycling of the filtrate and, moreover, the resulting polymer is in the form of fine particles having a diameter of 0.1 to 1.0 µ and hence meets the requirements for a filler of paper (i.e., the capability of improving the opacity and other properties of paper).
424508
Aikawa Naoyuki
Ifuku Naoyuki
Kurokawa Akio
Seita Kenzo
Usami Kaoru
Mitsui Chemicals Inc.
Sim & Mcburney
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