After the composite film is cured in 50-60 ℃ environment, the adhesion fastness is poor, the peeling strength is low, and the quality is not up to the requirements. There are many reasons and the situation is complicated, which should be paid attention to.
(1) The type of adhesive is not suitable for the substrate to be compounded. The appropriate adhesive must be selected according to the end use of the substrate and the composite film. For example:
① High temperature resistant (12L ℃ or 135 ℃) cooking adhesive should be selected for high temperature resistant composite film, and special high temperature resistant adhesive should be selected for different substrates (aluminum foil and plastic), and adhesive should not be used arbitrarily.
② When packaging liquid, sour and spicy food, such as pickled mustard, pickle, juice, etc., when aluminum foil compound, it is necessary to select the special adhesive for aluminum foil with acid resistance, otherwise, choose general-purpose adhesive.
(2) The surface temperature of steel roller is too low, which leads to insufficient activation of adhesive, low viscosity, poor infiltration of the second base material and poor adhesion force, resulting in poor adhesion between the two substrates and affecting the bonding fastness. According to the requirements of composite process, the surface temperature of composite steel roller can be maintained at 75 ~ 85 ℃.
(3) Insufficient glue. The main reasons are as follows:
① Dot depth is not enough and glue concentration is low.
② The net roller is not clean and the mesh point is blocked. A small amount of unwashed glue will crosslink and solidify, and the more accumulated, the depth of dot will gradually become shallow, resulting in the decrease of glue amount. High efficiency washing solution can be used to soak the blocked net roller and clean it with wire brush. If it can not meet the requirements, it is necessary to replace a new one.
(4) The penetration of the adhesive to the ink is poor, floating on the surface of the ink layer, and the adhesion fastness between the ink and the substrate is not good. The ink film is pulled down by the adhesive when peeling off. The performance is that the adhesion fastness is worse in the places with multi colors and thick ink layer, and the ink layer transfer occurs.
resolvent:
(1) Choose low viscosity, high solid content adhesive.
(2) The drying speed is slower, so that the glue has sufficient time to penetrate and reach the surface of the substrate.
(3) Increase the amount of glue properly.
(4) Select the appropriate ink, improve the surface tension of the substrate, improve the adhesion fastness of printing ink.
(5) The surface tension of the film is less than 38mn / M due to the poor corona treatment on the surface of the film, which results in poor bonding fastness of printing and lamination. The surface tension of the substrate should be carefully tested, and it must be increased to more than 38mn / m.
(6) The residual amount of solvent is too large. After compounding, many tiny bubbles are formed and the two substrates are separated. It can increase the temperature of drying channel or reduce the compounding speed without using high boiling point solvent.
(7) After compounding, the curing is not complete and the final bonding fastness value is not reached. The main reason is that the curing temperature is low and the curing time is too short. Generally speaking, the compound should be put into the environment of 50-60 ℃ for more than 48 hours as soon as possible. Otherwise, the effect is poor.
(8) The purity of diluent is not high, it contains water, alcohol and other active substances, which consumes a part of curing agent, resulting in the actual proportion of the main agent and curing agent in the adhesive, which affects the adhesion. Therefore, in the selection of solvents, it is necessary to pay attention to its quality and strictly prevent the mixing of moisture.
(9) The additives in the film make the adhesion fastness decrease, and this effect usually appears after 7 days, and there is a trend of gradual decrease. The resin raw materials without or less additives should be selected.
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.
We uphold the integrity of cooperation, good quality, good service business philosophy, won the industry's approval, products sold to all over the world; welcome friends from all walks of life to inquire, visit our factory to investigate guidance and business negotiations.