フェノール樹脂-ポリビニルブチラール混合系塗膜の粘弾性

第2報:両樹脂間の化学反応性

抄録

In a previous paper of this series, it was shown that there is a possibility of chemical reac-tions taking place between phenol reisn and polyvinyl butyral molecules during curing process of their mixture, the possibility being deduced from the occuring of a new loss peak (called a2-dispersionn or α₂-peak in the previous and this papers) at about 160°C.
In the present paper the mechanism of reaction between phenol resin and polyvinyl butyral is, systematically investigated by means of the vibrating reed method using model materials which are-derivatives of polyvinyl butyral differing only in side groups.
So far as the structure of polyvinyl butyral molecule is concerned, the occurring of α₂-peak of the mixed system is related to the existance of hydroxyl group, but not acetyl or butyral group, on the molecule. This is supported by the results obtained on a few types of polyvinyl butyral. resins found on the market. Therefore, the effect of hydroxyl groups of polyvinyl butyral molecule mixed with phenol resin on the occuring of the α₂-peak may be explained as follows: When a. mixture consisting of phenol resin (A-Stage) and polyvinyl butyral is heated at a high temperature, some graft or cross-linked structure will be produced by co-condensation reaction between hydroxyl groups on polyvinyl butyral and methylol or amino groups on phenol resin molecules during the course of curing reaction. This hypothesis is supported by the fact that above 170°C the dynamic elastic storage modulus of a specimen of polyvinyl butyral mixed with phenol resin, in contrasted with the case of derivatives of polyvinyl butyral lacking in hydroxyl group on the molecule, in-creases again with the rise of measuring temperature except when the content of phenol resin in the mixed system is high.