Dry lamination is a process in which two or more types of plastic film adhesives are bonded together by using dry laminating equipment and adhesives. The dry lamination process includes: gluing, drying, compounding and curing. Its principle is to use gravure coating or roll coating method, the organic solvent adhesive evenly coated on a substrate to be compounded, after drying the organic solvent through the drying channel, and then through the steel roller and another rubber roller, the glued base material and another film are pressed together, and cured through a certain time and temperature, and then the composite packaging film required in industry is made.
1、 Equipment:
The operation part of the 600 mm wide dry compound machine produced by Shaanxi printing machine factory has left and right adjustable receiving and discharging devices, drying channel (adjustable temperature 0 ~ 180 ℃), steel roller temperature (internal heating type, 0 ~ 180 ℃), steel roller and rubber roller pressing (pressure can be adjusted manually), and magnetic clutch is used to adjust tension in winding and unwinding.
According to the needs of production, three parts of the original equipment were reformed
1. The original equipment is to adjust the amount of glue by changing the distance between the two steel rollers. Improper operation often occurs and the shaft is broken due to excessive extrusion force between the two steel rollers. After that, it is changed to gravure wire roller, scraper and rubber pressure roller to adjust the glue loading amount. The only drawback after modification is that there are many specifications of rubber rollers, and one rubber roller is needed for a variety.
2. The corona processor is installed in the unwinding Part B to corona treat the other substrate.
3. In view of the need of laminating 0.007mm aluminum foil, the unwinding B is modified and the upper and lower balance fine adjustment device is added to make the incoming aluminum foil smooth and wrinkle free.
2、 Raw materials:
There are a lot of raw materials that can be used for dry composite. In principle, as long as it is coiled material, it can be used. Commonly used are: OPP, pet, PP, CPP, PE, PVC, nylon, aluminum foil, paper, etc.
Note: 1. The raw materials used for gluing and laminating must be corona treated before gluing, otherwise the bonding firmness will be greatly affected. Generally, the products sold in the market have been treated and the treated surface should be recognized. 2. Aluminum foil must not be corona treated, otherwise conductive fire, injury. 3. The paper with too small tension should not be used for laminating, otherwise it is easy to break. Generally speaking, it should not be less than 40 g / m2. The wider the width, the better. The wider the paper must bear the greater tension.
3、 Process operation:
The coil to be prepared for lamination should be neat, and if not, it should be tracked and aligned on the slitting machine. Recognize the corona treatment surface, glue must be applied to this side, string the material belt through the drying channel, overpressure steel roll to the receiving roll, and mix the glue according to the requirements of composite crafts. For single component plus solvent and two-component, mix component A with solvent, and then add component B. after that, add the glue tank. Do not be too full. Otherwise, glue will overflow in one start-up and waste a lot. One component can be matched for one shift, and two components should be used at the same time. Otherwise, the bonding strength of the two-component adhesive is different after compounding. Moreover, if the two-component adhesive is placed for a long time, curing will occur.
Adjust the oven temperature to the required temperature, adjust the pressing steel roller temperature to the required temperature, and adjust the tension of unwinding a and unwinding B to make them match.
Driving: speed from slow to fast to normal. Check the composite quality, whether there are transverse wrinkles, bubbles, etc. Tension control is the key to cross wrinkling. Vertical wrinkle depends on whether the roller is horizontal.
After parking, the rubber roller should be cleaned up, otherwise the glue amount will be less and less until it can not meet the requirements, and the composite firmness will decline and become waste products; at the same time, all guide rollers and the whole system should be cleaned up, otherwise, it will be difficult to clean up after drying.
4、 Several key issues:
a) The relationship between the amount of glue and the wire of wire roller is as follows
The amount of glue can be adjusted to solve the problem. The thicker the glue is, the more glue is put on, but it is not easy to operate and the fluidity is poor. Now introduce how to change the wire roller wire to solve the problem of glue. The more glue is on, the less mesh cable is used. The general laminating film uses 175 lines (making general bags). For high requirements, 120 ~ 140 lines are used for sealing film (milk cover), and 100 lines or less must be used for special high-quality bags, so as to ensure the bonding fastness. Therefore, professional flexible packaging manufacturers should prepare three sets of wire roller to ensure the production needs.
b) The relationship between the scraper and the amount of glue applied
The tighter the scraper is, the less glue will be put on it, and the closer it is to the tangent line of the wire roller, the less glue there will be, otherwise, the more glue. This cannot be ignored.

c) The control of oven temperature is considered according to solvent evaporation. As long as the solvent is evaporated, otherwise, there is solvent smell in the bag, which will affect the product quality. On the other hand, we should also consider the driving speed. The faster the speed is, the shorter the residence time in the drying channel is, and the higher the required temperature is, so as to dry out the solvent.

d) Service time and maintenance of wire roller:
At the end of each lamination, the wire roller should be cleaned, especially the glue in the mesh should be cleaned with copper brush and thinner to ensure normal use next time. With the increase of driving days, it is not enough to check the abrasion of the wire roller and the situation of curing glue in the mesh at any time. We have had several quality accidents due to the lack of glue on it. Therefore, it is necessary to replace the wire roller after two months of continuous use.
e) The causes of transverse and vertical wrinkles are as follows
The cause of cross wrinkling is caused by the tension mismatch between the two layers of film. The plastic film itself has certain tensile property under the action of tension. When a film (thick and strong tension) is stretched, the tension disappears, it will return to its original state. After this process, the transverse wrinkle occurs. The greater the stretch, the more severe the transverse wrinkle.
Vertical wrinkle depends on whether the roller is horizontal. If one of them is not level, the material will not be leveled after being pressed into the steel roll. Therefore, it is necessary to carefully check the levelness of the roll before the steel roll is put into it, so as not to deform it.
f) Causes and solutions of bubbles:
There are several reasons for the bubble: first, the mixing is uneven, the solvent volatilization is not complete; second, the glue pressing roller and hot pressing roller have pitting and line lines; third, the hot pressing roller is not compressed; fourth, the glue content is too small and the concentration is too thin. These problems should be noted, the glue should be preheated in winter, and the ambient temperature should not be too low.
g) Influence of moisture content:
There is a certain amount of moisture in the diluent, resulting in the decrease of adhesion. Therefore, attention should be paid to the quality of the thinner. The humidity also seriously affects the gluing. Generally, if the humidity is higher than 70%, it will not be able to ensure normal gluing. Especially in summer, the workshop temperature is high, acetone volatilization, resulting in the glue system temperature is quite low, water vapor in the cots and wire roller part of a large amount of condensation, damage to the glue coating state, and will seriously reduce the adhesive adhesion.
h) Environmental impact:
The dust in the air will adhere to the adhesive film and affect the adhesion force. Especially at the air outlet of the oven, the strong airflow will pick up dust particles and scatter on the adhesive film. Therefore, the environment should be kept clean and the filter screen at the air supply outlet should be cleaned regularly.
Above, we discussed the influence factors of dry lamination and some methods to improve the effect of compound glue. The normal production process is relatively complex, and it needs more comprehensive consideration when analyzing a certain quality problem.
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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