Control points and precautions of the hottest prec

2022-08-02
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Control points and precautions of pre coating and film covering process

pre coating and film covering means that the film coated with adhesive in advance is pressurized and heated by the rubber roller and the heating roller, and then bonded with the paper products to form a paper plastic integrated product to avoid product appearance problems; (2) Material selection: senior material engineers can develop colors according to customer requirements, so as to ensure better performance, quality and materials of the fatigue testing machine; (3) Mold design: professional mold engineers provide gate structure, position and waterway layout design to ensure product appearance; (4) Process design: professional mold testing engineers provide professional mold adjustment services. The process flow of precoating and laminating is roughly as follows: paper feeding at the paper feeding table, printing press film and receiving the finished products

preparation before film coating

(1) the thickness of BOPP film used for film coating shall generally be between 0.01-0.02MM, the transparency shall be more than 90%, and the heat shrinkage rate shall be small

(2) before using the machine, check whether the P film is within the warranty period, whether the adhesive coating on the film is uniform, and whether the surface is scratched or crushed when cleaning the inverted metallographic microscope. The gluing surface of the film shall pass through the heating roller and face the printed matter

(3) the rubber roller and heating roller must be kept clean, and the pressure balance rollers on both sides must rotate flexibly

(4) adjust and determine the gap of the paper feeding roller according to the paper thickness

(5) select BOPP films with different widths according to the product size, and adjust the side gauge according to the product requirements

(6) adjust the film guide roller so that the tension on both sides of the film is consistent and the surface of the film is free of wrinkles

key points of pre coating process control

the key technologies of pre coating process are mainly the control of coating temperature, pressure and speed

1. coating temperature

temperature is the primary factor for precoating, because the adhesive on the precoating is hot melt adhesive, and the temperature determines the melting state of the hot melt adhesive, and determines the penetration and diffusion ability of the hot melt adhesive molecules to BOPP film, printing ink layer, paper, etc. Although the increase of the coating temperature helps to enhance the bonding strength, too high a temperature will shrink the film, make the product surface shiny and blistered, and make the product wrinkled. According to practical experience, the coating temperature should be controlled between 70 ~ 100 ℃

2. Coating pressure

the surface of the paper is not smooth. Only under the appropriate pressure, the hot melt adhesive in the molten state can completely cover the surface of the printed matter, and the coated products can be bright with good bonding effect. Low pressure and poor adhesion; Higher pressure helps to improve the adhesion between film and paper products. However, if the pressure is too high, it is easy to wrinkle the product and damage the surface of the rubber roller. Deformation, reduce the service life of the rubber roller. With the increase of the pressure, the contact pressure between the rubber roller and the heating drum will increase, the load on the shaft head and bearing of the two rollers will increase, the wear will increase, and the load on the transmission system will increase. Therefore, too much pressure will affect the service life of the whole machine

in actual production, the pressure should be adjusted according to different paper. For example, for loose paper, the pressure should be greater, and vice versa. According to experience, the film covering pressure is generally set at 8 ~ 25MPa

3. film covering speed

the speed of film covering determines the melting time of the adhesive on the pre coating film on the heating drum and the contact time between the film and the paper. The film covering speed is slow, the heating time of the adhesive on BOPP film is relatively long, the pressing time of film and paper is long, the bonding effect is good, but the production efficiency is low. The coating speed is fast, the heating time of the adhesive on BOPP film on the heating roller is short, the contact time between film and paper is short, and the bonding effect is poor. Domestic precoating and laminating equipment "For example, the production speed of the equipment is generally controlled between 5-30m/min.

above, the three key process technologies in the precoating film covering - film covering temperature, film covering pressure and film covering speed are simply analyzed, but the adjustment and coordination among the three should be flexibly mastered according to the actual conditions such as the different equipment used, the different types of film covered products and the different types of film used. Only in this way can high-quality film covering be obtained Products

4. Special printing crystal coating parameter control

special printing refers to printing with large printing area, thick ink layer, deep color, large water content and large paper size. When laminating this kind of printed matter, the laminating parameters are generally controlled as follows

film covering temperature: 95 ~ 5 ℃

film covering pressure: 16-25mpa

film covering speed: 5-10m/min

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