Polyurethane is widely used and has good wear resistance. It is an ideal material for encapsulation. However, the problem often encountered in polyurethane encapsulated products is degumming. How to solve the problem of degumming of encapsulated products? First of all, we have to figure out the reason for degumming.
1. The influence of mold and iron core temperature
During the pouring process of the polyurethane material liquid, the temperature of the iron core and the mold is required to be close to the temperature of the polyurethane material liquid. When the temperature difference between the two is large, the curing speed of the material will be uneven, and the result will be greater internal stress after the curing of the polyurethane material. Roller encapsulation
2. Mold planning and demolding requirements
When the mold is planned and manufactured, it is required to have good sealing, easy to close, open and release the film. When planning the mold, the heat balance of the polyurethane should also be considered, which is an important factor that is simply ignored by the manufacturers. If the rubber roller is unevenly heated during the high temperature vulcanization process, the polyurethane vulcanization is generally incomplete at the junction of the iron core and the polyurethane, the strength of the elastomer is low, or cracks appear.
3. Selection of adhesive
According to the theory of adhesion coordination bonds, coordination bonds and van der Waals forces can be formed between polymer materials with high molecular properties and the appearance of metal materials, and a tight bond between the materials and the metal can be formed.
4. Treatment of iron core
The treatment of the cast iron roller core is also one of the key factors in the core removal of the rubber roller. For a good combination of polyurethane elastomer and the iron core, the iron core generally needs to be cleaned, such as pickling to remove rust, using materials, etc., so that its appearance is clean and non-stained. Mechanical sandblasting is generally one of the methods for bonding strength.
To use, to ensure that the encapsulation is not degummed, the following steps must be installed:
1. Grinding of the encapsulation According to the required size and shape, the encapsulation needs to be processed with a CNC grinder when the requirements for the appearance of the encapsulation are high.
2. The surface of the rubber-coated iron core is roughened. The surface of the polyurethane rubber-coated iron core is roughened to increase the adhesion between the surface of the rubber-coated iron core and the rubber.
3. Sandblasting The rough-treated rubber-coated iron core is subjected to sandblasting. Sandblasting will select sand of different properties according to the material of the rubber-coated iron core.
4. Cleaning the iron core If it is a new rubber-coated iron core, it is necessary to clean the greasy dirt on the surface of the iron core with a cleaning agent.
5. Laminated vulcanization The encapsulation after encapsulation generally requires a vulcanization time of 10-15 hours. After vulcanization, the encapsulated iron core and the encapsulation will be tight.
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