How to solve the problem of small bubbles in the composite film: if there are small bubbles in the composite, it will not only affect the appearance quality, opacity and fogging, but also affect the peel strength of the composite, which is a very bad phenomenon. The solutions are summarized as follows: (1) the surface tension of the base film is too small, the wettability is poor, the glue is not uniform, and there are gaps and bubbles in the place without glue. (2) The pressure of the composite roller is insufficient, or the surface temperature of the steel roller is too low, the adhesive activation is insufficient, a little bit of colloidal particles flow unevenly like the dot, there is a small gap, resulting in very small bubbles. At this time, the surface temperature should be increased and the pressure should be increased. (3) The angle between the compound roller and the die is not suitable and the wrap angle is too large, especially for the material with large rigidity, it is easy to cause wrinkles and even bubbles. The angle should be adjusted carefully, the wrapping angle should be changed, and the compound roller should be entered as far as possible according to the tangent direction. (4) Dust adheres to the surface of the film. The dust particles lift up the two-layer film and form a circle of gap around it. The empty ring is a little bubble in the rough view, and there is a black spot in the middle. If there is such a phenomenon, please pay attention to the clean environment and keep the air fresh. (5) When a small amount of water is mixed into the adhesive, the - NCO in the adhesive reacts with water to form CO2 gas and bubbles. Therefore, it is necessary to keep the solvent and environmental humidity dry to eliminate the cause of CO2 generation. (6) There are many residual solvents, and the permeability of the solvent is poor. Therefore, it is necessary to control the amount of residual solvent, or use the base membrane with high transmittance of the solvent to compound. The main reasons for poor adhesion are as follows: 1) the amount of curing agent is not enough. The insufficient curing dose may be directly caused by the insufficient proportion of the curing agent. The addition of less curing agent has a great influence on the bonding. It may also be caused by indirect reasons, such as too much water in the diluent, which consumes the curing agent, which not only causes poor adhesion, but also causes surface quality problems. It is also possible that the curing agent has not been used up for the first time and has not been covered well, resulting in water entering and consuming the curing agent. ② Less glue. A small amount of glue also causes poor adhesion. Bonding mainly depends on adhesives, if the amount of glue is small, the consequences can be imagined. ③ The electric activation of the membrane. The surface of the composite membrane must be clean, dry, flat, dust-free and oil-free. For non-polar polyolefin materials with dense and smooth surface, it must be treated by electric activation. There are two principles of electroactivation: first, electric shock or breakdown. Under the high-voltage electric field, the electron flow strongly impacts the plastic film, and increases with the increase of current and voltage, which makes the surface roughened and rough, and increases the surface area, thus producing a good wetting effect and increasing the adhesion fastness; second, under the action of the electric field, the oxygen in the air becomes stinky Oxygen and ozone are decomposed into oxygen and new ecological oxygen atoms, and the new ecological oxygen atom is a very strong oxidant. It oxidizes a-carbon in polyethylene and polypropylene molecules to make it into carboxyl or hydroxyl group. With this structure, the molecular polarity increases, the surface tension increases, and the adhesive has a great affinity and attraction to the adhesive with great polarity Fastness. Therefore, the electro activation treatment is very important. In addition, after corona treatment, the film should be used in time for printing and laminating. The storage time should not exceed one month. If the storage time is longer, the initial value of corona treatment should be increased by 2-4 dyne / C m2. ④ The water content of solvent is high. The high moisture content of solvent will lead to weak bonding, which is mainly caused by the reaction between moisture and curing agent-n = C = 0 group. This problem is raised again, hoping to attract enough attention of composite manufacturers. ⑤ Ink connection material problem. The function of the ink binder is to combine the ink and the outer membrane. If the binder is not good, it will make the ink and the outer membrane separate and completely transfer to the inner membrane. ⑥ Chemical penetration. Some composite films have good composite strength before packaging, but after they are used for packaging, the phenomenon of delamination and blistering will appear. Most of the reasons are that the penetration of chemical substances in the contents will corrode the membrane, glue or ink. This leads to this situation. Therefore, for pesticides, drugs and some other chemical products of composite packaging bags to consider the appropriate film, glue or ink. ⑦ If the air humidity is too high, the moisture will consume NCO of curing agent.
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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