PURPOSE: To efficiently and simply graft a vinyl monomer onto PVA by utilizing a free radical which is formed by introducing an SH group to PVA and reacting the SH group with persulfate ion.
CONSTITUTION: First, an SH group is introduced into PVA by a method for reacting an SH-containing silane coupling agent such as mercaptomethylmethoxysilane with a hydroxyl group at a PVA side chain at 60-100°C for 15 minutes to 1 hour. Then the introduced SH group is reacted with persulfate ion to generate a free radical on the PVA. Then, the free radical is used as a reaction point and a vinyl monomer is grafted on the PVA. The graft reaction, for example, is carried out by treating the PVA into which the SH group is introduced with a graft reaction solution containing a vinyl monomer such as methacrylic acid and potassium persulfate. The reaction is generally carried out at 1-10% vinyl monomer concentration at 40-80°C for 15 minutes to 2 hours.
TAKIGAMI SHOJI
UEISHI YOICHI
