1. Saturated polyester resin
Saturated polyester resin (oil-free alkyd resin) is mainly used in the production of coil coatings. Depending on the resin performance and structure, it can be used for the top coat, primer, and back paint of coil coatings, as well as ink and thermal film. Saturated polyester resin for coils.
Characteristics of saturated polyester resin:
Saturated polyester resin requires that the coating film has good decoration, protection, durability, construction and processing and formability. 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 construction industry.
(2) It has outstanding hardness and toughness, and has anti-fouling resistance, and the use level is higher.
(3) Economy. It is suitable for coil coating with general requirements.
2. Unsaturated polyester resin
Unsaturated polyester resins are generally linear polymer compounds with ester bonds and unsaturated double bonds formed by condensation polymerization of unsaturated dibasic acid diols or saturated dibasic acid unsaturated diols. Usually, the polyesterification polycondensation reaction is carried out at 190-220℃ until the expected acid value (or viscosity) is reached. After the polyesterification condensation reaction is completed, a certain amount of vinyl monomer is added while hot to form a viscous The liquid, such polymer solution is called unsaturated polyester resin.
Features of unsaturated polyester resin:
(1) Heat resistance. The heat distortion 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 compressive strength.
(3) Chemical resistance. Unsaturated polyester resin has better resistance to water, dilute acid, and dilute alkali, and poor resistance to organic solvents. At the same time, the chemical resistance of the resin can vary greatly depending on its chemical structure and geometric switch.
(4) Dielectric properties. The dielectric properties of the unsaturated polyacid resin are good.
(5) The unsaturated polyester resin changes from a soluble and meltable state to an insoluble and non-meltable state.
(6) It can still be dissolved in a suitable solvent and has good fluidity when heated.