1. Saturated polyester resin
Saturated polyester resin (oil-free alkyd resin) is mainly used for the production of coil coatings. Depending on the properties and structure of the resin, it can be used for the top coating, primer, backing of coil coatings, and also for inks and thermal coatings. Saturated polyester resin for coils.
Characteristics of saturated polyester resin:
Saturated polyester resin requires good decorativeness, protection, durability, workability and processability of the coating film. The most used polyester topcoat is because the saturated polyester resin has the following characteristics:
(1) Strong versatility and good weather resistance. Mainly suitable for steel plate coating in the construction industry.
(2) The hardness and toughness are outstanding, and it has stick resistance, and the use grade is high.
(3) Economical. Applicable to the general requirements of coil coating.
Second, unsaturated polyester resin
Unsaturated polyester resin is generally a linear polymer compound with ester bond and unsaturated double bond formed by polycondensation of unsaturated dibasic acid diol or saturated dibasic acid unsaturated diol. Generally, polyester The polycondensation reaction is carried out at 190～220℃ until it reaches the expected acid value (or viscosity). After the polyester polycondensation reaction is completed, a certain amount of vinyl monomer is added while hot to form a viscous liquid. The polymer solution is called unsaturated polyester resin.
Characteristics of unsaturated polyester resin:
(1) Heat resistance. The thermal deformation temperature of most unsaturated polyester resins is 50～60℃, and some resins with good heat resistance can reach 120℃.
(2) Mechanical properties. Unsaturated polyester resin has high tensile, bending, and compression strength.
(3) Chemical resistance. Unsaturated polyester resin has good performance in water, dilute acid and alkali, and poor resistance to organic solvents. At the same time, the chemical resistance of resin varies with its chemical structure and geometric switch. There can be big differences.
(4) Dielectric properties. The dielectric properties of unsaturated polyacid resins are good.
(5) The unsaturated resin changes from soluble and meltable state to insoluble and infusible state.
(6) It is still soluble in a suitable solvent and has good fluidity when heated.