Preparation Of Mixture For Sealing Pole
2.1 Preparation before the mixture is prepared
Epoxy resin needs to be added with curing agents such as amines or anhydrides to cure. However, the amount of curing agent added will directly affect the performance of the cured product. Therefore, it is necessary to select a suitable curing system according to the epoxy resin system used, and determine the ratio between the components according to the type of filler selected.
The epoxy resin casting material has a working life of 1 to 2 days at room temperature (25°C), a trial period of 6 to 8 hours at 40 to 45°C, and a high reactivity at high temperatures of 140 to 160°C, and gels quickly in a short time. Before the daily mixing production, the epoxy resin, curing agent, silica powder and color powder should be weighed according to the daily output and the proportion of the mixture components.
In order to ensure that the fluidity of the material meets the requirements of the casting process, when the room temperature of the mixing room is lower than 20℃, the epoxy resin needs to be preheated one night in advance, and the epoxy resin is placed in an oven at 45±5℃ for heating (6~10)h. When the room temperature is higher than 20℃, it does not need to be heated.
2.2 Mixing and degassing of the mixture
Pour the weighed epoxy resin, curing agent and silicon micropowder into the mixing tank in order. In order to make the mixing of the mixture more uniform, the order of pouring the materials is epoxy resin, silicon micropowder, curing agent, color powder, and then clean the residual resin and filler at the tank mouth, push the mixing tank onto the stirring rack along the guide rail, and lower the mixing cover for stirring. At this time, ensure that the sealing ring on the mixing trolley is in the sealing groove.
At the beginning of stirring, the epoxy resin, curing agent and silicon micropowder need to be stirred evenly. At this time, the speed of the mixing tank can be set to 10r/min~20r/min. After all the fillers are mixed into the resin, about 5 min to 10 min later, increase the speed of the mixing trolley and start vacuuming, and the mixture begins to degas. When the mixture begins to degas, turn on the heating control switch of the mixing rack control panel and the mixing trolley at the same time, set the heating temperature to 30-40℃, and ensure the fluidity of the mixture. 2.3 End of mixing Longyuan .cn The degassing time of the mixture can be observed through the window. When the mixing is stopped, if there are still bubbles on the surface of the mixture, the degassing time should be appropriately extended until the bubbles are basically gone. When the vacuum degree of the mixture is ≤120Pa, the degassing time can meet the use requirements within 70-130min. At the end of mixing, stop stirring first, close the vacuum pipeline valve, then open the exhaust valve to release air, and finally stop the vacuum pump. After the raw material is degassed, close the lid of the trolley and tighten the fastening bolts. 3 Conclusion
Bisphenol A epoxy resin itself is very stable and does not change even when heated to 200℃. However, its reaction activity is very high. Generally, epoxy resin can be cured under the action of curing agents such as acids or alkalis. Some curing processes can be initially completed at very low temperatures (-5℃) or at room temperature; some curing reactions can only be carried out at high temperatures. The curing process is often accompanied by heat release, which in turn promotes curing. Since no small molecular compounds are released during the curing process, epoxy resin avoids the bubbles and shrinkage defects generated by some condensation-type polymer resins during the thermal curing process. This paper analyzes the material properties of epoxy resin mixtures and the preparation process of the mixtures. Prepare a mixture that meets the Embedded Pole APG process production.
