Método para la fabricación de un copolímero de etilvinilacetato para un encapsulante de células solares y la resina obtenida por el mismo

摘要

The invention relates to a method for specifically supplying monomers to a tubular reactor and provides a method for preparing the ethylvinylacetate (EVA) copolymer of a solar cell sealing agent, and the EVA copolymer resin prepared based on the method. The EVA copolymer resin is low in thermal shrinkage, and high in transparency. The method includes the steps of feeding 67-76% of ethylene monomers and 24-33% of vinyl acetate monomers by weight to the only one inlet part of the tubular reactor, adding a peroxide-based initiator at the amount of 50 to 3000 ppm, and conducting the polymerization reaction at the temperature of 200-300 DEG C and at the pressure of 2500-3000 kg/cm2 for 2-20 minutes. The Z-average molecular weight (Mz) of the EVA copolymer resin is 220,000 g/mol or smaller, and the molecular weight distribution (Mw/Mn) thereof is 4.3 or less. Meanwhile, the melt flow index is 6-35 g/10 minutes at the temperature of 190 DEG C and under the load of 2.16 kg. Therefore, the EVA copolymer resin is low in thermal shrinkage and high in transparency.