Push the combination of the charging car into the middle of the hot plate of the multi-layer press, the hot plate rises slowly, and after closing, it is pressurized and steam pressed.

The key of pressing process is to determine the process parameters, among which the important parameters are temperature, pressure and time. The pressure system first depends on the variety and properties of materials, and then considers the thickness of products, plate area and equipment conditions.

temperature

The first stage is from the chamber temperature to the material significant reaction temperature, that is, preheating stage. At this time, the resin melts and discharges some volatiles, and the pressure is generally 1 / 3 ~ 1 / 2 of the total pressure.

The second stage is the intermediate heat preservation stage. At this time, the resin melts and penetrates, and the reaction rate is low. The heat preservation time is determined according to the old and tender degree of the adhesive tape and the thickness of the product board. When the resin is close to gelation and stretched, the pressure should be increased and heated.

The three stages are warming up stage. This is to improve the curing degree of the resin. At this time, the reaction speed of resin is accelerated.

The four stages are the heat preservation stage, which aims to make the resin fully solidified. The temperature depends on the curing characteristics of the resin, while the curing time depends on the thickness of the plate.

The cooling stage is the cooling stage. Heating can be stopped when the end of the holding stage is reached, and then the cooling is slow and the required high pressure is maintained. The cooling rate has an effect on the flatness of the product surface. The cooling speed should be controlled. The cooling speed should not be too fast at the beginning of cooling. Demoulding can only be carried out when the cooling rate is below 50 ℃.

pressure

The function of pressure is to overcome the vapor pressure of volatiles, to make the adhesive resin flow, to make the adhesive cloth layer contact closely, and to prevent the deformation of the plate during cooling.

The molding pressure is determined according to the curing characteristics of the resin. When curing, if small molecules escape, the pressure should be higher; when the curing temperature is high, the molding pressure should be increased accordingly. In addition, the thickness of the product, the glue content of the adhesive tape and the heating rate should be taken into account.

time

The time from the beginning of preheating and pressing to the time of taking out the product is the pressing time, which is the sum of the pre pressing, hot pressing and cooling time. The pressing time is related to the curing speed of resin, the thickness of the laminate and the pressing temperature, which is based on whether the laminate can be fully cured.

The preloading time depends on the properties of the adhesive tape. If the content of insoluble resin is high and the volatile content is low, the preloading time is short, otherwise it should be relatively prolonged. The hot pressing time is to ensure that the resin in the adhesive tape is fully cured. If the hot pressing time is too short, the resin curing is incomplete, and if it is too long, the performance of the product will decline. It needs to be determined by repeated tests. Cooling time is a link to ensure the quality of products. If the cooling time is too short, it will easily lead to warpage and cracking; if it is too long, it will reduce the production efficiency.

Cooling demoulding

After the heat preservation, the heat source can be turned off and the natural cooling or cooling by cold air or cold water should be adopted. However, the pressure should not be lowered too early, otherwise the surface of the product will blister or warp. The demoulding temperature is generally lower than 60 ℃.

Post processing

The purpose of post-treatment is to further cure the resin until it is completely cured, and at the same time partially eliminate the stress in the product and improve the performance of the product. The post-treatment of epoxy board and epoxy phenolic board is 120 ~ 130 ℃ for 120 ~ 150 minutes, which can improve the mechanical and electrical properties of the products.