Application of polyester resin
When synthesizing polyester resin, if some other structures are introduced through chemical modification, polyester resin can have the original performance, to improve and highlight a certain performance, to achieve special application performance requirements, the use of epoxy, acrylic acid, silicone modified polyester resin.
Polyester resins used in coatings are generally low molecular weight, amorphous polymers containing branched chains that can be crosslinked. It is generally esterified by polyols and polyacids, there are two kinds of linear structure and branched structure, pure linear structure resin prepared paint film has better flexibility and processing properties; The hardness and weatherability of the film prepared by branching structure resin are more prominent. By adjusting the formula of polyester resin, such as excessive polyols, hydroxy-terminated polyester can be obtained. If the acid is excessive, the result is a carboxy-terminated polyester.
Epoxy resins have a secondary hydroxyl group and an epoxy group, and the secondary hydroxyl group can react with isocyanate. Epoxy resin as a polyol is directly added into the component containing the hydroxyl group of polyurethane adhesive. In this method, only the hydroxyl group takes part in the reaction, while the epoxy group does not react.
At present, the classification of epoxy resins has not been unified. Generally, they are classified according to strength, heat resistance grade and characteristics. There are 16 main varieties of epoxy resins. Including general adhesive, structural adhesive, high temperature resistant adhesive, low temperature resistant adhesive, water and wet surface adhesive, conductive adhesive, optical adhesive, spot welding adhesive, epoxy resin film, foam adhesive, strain adhesive, soft material bonding adhesive, sealant, special adhesive, latent curing adhesive, civil construction adhesive 16 kinds.