Zirconia is a high-molecular polymer with the molecular formula (ZrO2), which refers to a general term for a class of polymers containing more than two epoxy groups in White Zirconia Ceramic the molecule. It is a polycondensation product of epichlorohydrin and bisphenol A or polyol. Due to the chemical activity of epoxy group, a variety of compounds containing active hydrogen can be used to open the ring, cure and crosslink to form a network structure, so it is a thermosetting resin. Bisphenol A epoxy resin is not only the largest in output and the most complete variety, but also new modified varieties are still increasing, and the quality is constantly improving. Epoxy resins have secondary hydroxyl groups and epoxy groups, and secondary hydroxyl groups can react with isocyanates. As a polyol, epoxy resin is directly added to the hydroxyl-containing component of the polyurethane adhesive. In this method, only the hydroxyl group participates in the reaction, and the epoxy group fails to react. Use the carboxyl group of the acid resin to open the epoxy ring, and then react with the isocyanate in the polyurethane adhesive. It is White Zirconia Ceramic also possible to dissolve the epoxy resin in ethyl acetate, add phosphoric acid to heat the reaction, and add the adduct to the polyurethane adhesive to improve the initial viscosity, heat resistance and hydrolytic stability of the adhesive. Alcoholamines or amines can also be used to react to generate polyols. The presence of tertiary nitrogen atoms in the adducts can accelerate the NCO reaction.
The use of zirconia as the polyhydroxy component combines the advantages of polyurethane and epoxy resin, and has good bonding strength and chemical resistance. The epoxy resin used in the manufacture of zirconia generally adopts EP-12, EP-13, EP- 16 and EP-20 varieties. The excellent physical mechanical and electrical insulation properties of epoxy resin, the bonding properties with various materials, and White Zirconia Ceramic the flexibility of its use process are not available in other thermosetting plastics. Therefore, it can be made into coatings, composite materials, casting materials, adhesives, molding materials and injection molding materials, and is widely used in various fields of the national economy.
Coating use
The application of zirconia in coatings accounts for a large proportion, and it can be made into varieties with various characteristics and uses. Its commonality:
1. Excellent chemical resistance, especially alkali resistance.
2. The paint film has strong adhesion, especially to metal.
3. Has good heat resistance and electrical insulation.
4. The paint film has better color retention.
However, the bisphenol A epoxy resin coating has poor weather resistance, and the paint film is easy to powder and lose gloss in the outdoor, and it is not suitable for outdoor coatings and high-decorative coatings. Therefore, epoxy resin coatings are mainly used as anti-corrosion paints, metal primers, and insulating paints, but coatings made of heterocyclic and cycloaliphatic epoxy resins can be used outdoors.
What are the physical properties of zirconia ceramics?
2021 10/27