When using two-component polyurethane adhesive to composite paper and plastic, the following problems should be paid attention to in the process of compounding
1. Two component polyurethane adhesive is a reactive adhesive, and it is very sensitive to the content of water and alcohol in solvent. At the same time, because the composite paper also has a certain amount of moisture, these will affect the full bonding of polyurethane adhesive. Therefore, great attention should be paid to the combination.
2. The surface of paper is rough and has many pores. Compared with plastic composite, the amount of glue is larger, otherwise it will affect the composite strength or produce bubbles.
3. Moisture content of composite paper. If the humidity is too high, the composite film will blister. The author came across a case in Hunan Province, where a flexible packaging manufacturer produced paper plastic packaging bags for areca products, with the structure of OPP printing / paper / PE. No matter from the appearance or peel strength of the composite products are impeccable, but in the process of bag making, bubbles appear at the heat sealing part. This phenomenon appears in the middle of the hot knife position, and both sides of the heat seal place does not appear bubble. The process of forming two bags at a time is adopted. The ironing knife on both sides is narrow and the ironing knife in the middle is wide. After heat sealing, the two bags are cut into two pieces by blade. Bubbles are generated in the middle of the wider heat seal, both sides of the heat seal will not appear bubbles. Later, through adjustment, in the process of bag making, the composite film was cut with a blade in the middle of the two bags, and then the bubble phenomenon disappeared through heat sealing. When cutting the composite film, because the moisture content of the paper is too high, the water vapor expands during heat sealing, and the water vapor at the narrow heat seal on both sides can run out from the incision, while there is no cut in the middle, the water vapor can only be bubbled in it to produce bubbles.
4. Because polyurethane adhesive is a reactive two-component adhesive, the relative initial adhesion force is poor when compounding paper. After the plastic film is glued, the drying channel temperature should not be too high, the tension should not be too high, and the temperature of the composite roller should not be too high, otherwise it is easy to curl or wrinkle.
Dongguan Beite packaging materials Co., Ltd. - located in Dongguan City, the world's manufacturing city, is a subsidiary of Beite packaging (China) Co., Ltd., with a plant area of 6000 square meters. It is a flexible packaging enterprise integrating R & D, production and sales. It has a complete set of domestic advanced production equipment, a scientific and humanized management system and a group of experienced technical personnel For backing, to provide customers with quality products and first-class service.
The company produces composite bags, roll film, fruit bags, aluminum foil bags, suction mouth bags, self-supporting bags, zipper bags, anti-static bags, special-shaped bags, etc., which are suitable for the internal and external packaging of food, daily chemicals, electronics, toys, medicine, cosmetics, industrial products and other industries.
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