The coating on the back of the color coated plate has poor adhesion. The main reasons for such problems are as follows:
(1) Glue reaction time: the length of glue reaction time when users are processing affects the foaming effect, and the effect of too long or too short hair bubbles will not be ideal, as shown in Figure 2 - (a), which is a sample of improper foaming time
(2) Coating quality: the type of coating determines the surface activity of the coating after curing, which will affect the foaming effect of the color coating plate and foaming agent. If the active group of coating is less, the foaming property will
be affected. It is a bad sample of coating foaming with less active groups.
(3) Glue quality: the foaming glue is generally composed of black glue and white glue. The white glue is polyether polyol with hydroxyl group, and the black glue is cyanate
ester. The two are mixed in a certain proportion to form polyurethane, which is called foaming material. The effective components in the glue seriously affect the foaming effect of the product. In order to reduce the cost, adding other substances in the
white glue or replacing polyether polyol with polyester polyol with lower price are likely to cause poor foaming
(4) Others: foaming process and production environment are also important factors affecting the quality of sandwich panel products.