The common lamination process is divided into one-step method and two-step method.
1. One-step fast curing EVA
The laminator is heated to 10°C-120°C, the components are released, and the components are pumped for 5-8 minutes → pressurized for 3 minutes, heated to 135°C-140°C → constant temperature curing for 15-20 minutes → vented and immediately taken out and cooled.
2. Two-step method for fast curing EVA
The laminator is heated to 100°C~120°C → put in the components → evacuated for 5-8 minutes, pressurized for 3 minutes, take out immediately after venting and cool down. Put the components in a curing oven, heat up to 135°C to 140°C, and cure at a constant temperature for 15 ~20min.
3. Two-step method of conventional curing EVA
The laminator is heated to 100°C~120°C, once the components are put in, and then evacuated for 5-8min→pressurized for 3min→take out and cool down immediately after venting→put the components into the curing oven, heat up to 145℃~150℃, and cure at constant temperature for 30min .
The main purpose of lamination is to encapsulate the laminated photovoltaic modules. The setting of process parameters during the lamination process has a great influence on the quality of the laminated photovoltaic modules. The main component lamination process parameters include the following aspects:
(1) Laminating temperature: It depends on the characteristics of the EVA used (melting temperature, curing speed), the actual temperature of the component during production, and finally through the laminating experiment, testing its gelation and tensile strength, and comprehensively determining these aspects Laminating temperature.
(2) Curing temperature: EVA curing.
(3) Heating rate: the heating rate is too slow, the heating and curing time of EVA is too long, because the cross-linking agent is decomposed by heat, EVA can not be cured; the heating rate is too fast, it is easy to produce bubbles.
(4) Vacuum time: one is to discharge the air in the gap between the packaging materials and the gas generated during the lamination process to eliminate bubbles in the assembly; the other is to create a pressure difference inside the laminator, which is required in the lamination process pressure. The temperature when EVA is completely melted is 80°C, so you must wait until the EVA is completely melted and reach the best molten state before the airbag can be pressed down. This is most conducive to exhausting the gas in the module and can reduce the generation of bubbles. According to the data analysis of the test temperature, the temperature on the module can reach 80°C after vacuuming for about 5 minutes (depending on the equipment and working conditions). At this time, the fluidity of EVA is relatively large, and the airbag is pressed down at this time, which is easy to cause To avoid displacement of components, the vacuum time can be extended to 6min.
(5) Inflation time: It corresponds to the pressure exerted on the component during lamination. The longer the inflation time, the greater the pressure. Because the general structure of the polymer formed after EVA cross-linking is relatively loose, the presence of pressure can make the EVA film more dense after curing, have better mechanical properties, and can also enhance the adhesion of EVA to other materials.
(6) Laminating time: It is the holding time of the pressure exerted on the component. The process of starting to press down the airbag is the process of expelling the remaining gas inside the module, and applying a certain pressure to the module, so that the molecular structure of the EVA film after curing is denser, has better mechanical properties, and enhances the adhesion of EVA and other materials. Join forces. According to the results of tensile test and gel degree, setting the pressure and lamination time to 9 minutes can make the gel degree reach 65%~95%.