Factors Affecting The Performance Of Polyurethane Screen Plate

Date: 2025-06-12     From: Longding     Author: admin

The main factors affecting the performance of polyurethane screen plate are the molecular weight of oligomer polyol, NCO content in pre-polymer, isocyanate index, cooperating agent and reaction temperature.

Factors affecting the performance of the polyurethane screen plate

1. Influence of the molecular weight of the oligomer polyol

The size of the relative molecular mass of the oligomer polyol determines the density of polar groups in the polyurethane elastomer. Polyester-type polyurethane elastomer with the increase of the relative molecular mass of oligomer polyol, physical properties improve, hydrolysis resistance decreases; polyether-type polyurethane elastomer with the increase of the relative molecular mass of oligomer polyol, its flexibility and hydrolysis resistance increase, but the tensile strength and modulus will decrease.

2. Influence of NCO content in the prepolymer

NCO content is an important indicator to characterize the quality of the prepolymer, but also an important basis for calculating the dosage of the chain extender. Increase in the content of prepolymer, the prepolymer viscosity is reduced, easy to defoam and mix, and the product hardness, strength are higher. Lower content in the prepolymer, the product’s hardness, strength decreased, viscosity increased.

3. Influence of isocyanate index

Isocyanate index refers to the molar ratio of polyisocyanate and oligomer polyol. In the synthesis of prepolymer, the closer the NCO/OH ratio is to 1, the greater the viscosity of the prepolymer, bringing difficulties in casting. When the NCO / OH ratio exceeds 2, the prepolymer viscosity will be significantly reduced, and prone to esterification reaction or free isocyanate, decreased storage stability. Therefore, the NCO/OH ratio is generally selected between 1.5 and 2.2 as the best. Because in this ratio range, the prepolymer viscosity is moderate, easy defoaming operation, the product’s overall performance is better.

4. Influence of reaction temperature

improve the mixing temperature of prepolymer and chain extender, can improve the compression permanent deformation properties, but the tensile strength and tear strength will be reduced, the life of the kettle and shorten the gel time, such as the use of too low a mixing temperature, on the one hand, the solid chain extender is not allowed, on the other hand, although conducive to the kettle to extend the life of the kettle and improve the physical properties, but not easy to defoam and mixing is not homogeneous, so in practical terms Only a moderate temperature range can be used.