pvc film vacuum blister process pvc blister film

　　PVC film pressing technology is very important in the furniture industry, especially in the production of door panels and cabinets. Medium and high-density substrates are processed into various linear shapes and then blister-formed with various matt, high-gloss, color and texture PVC films, making the products colorful and dazzling, creating a lot of choice for consumers. However, products manufactured using this technology. Its quality varies greatly. The reasons for these differences are in addition to the factors of the base material and the facing material PVC blister film itself, the control of the process parameters during the processing is also very important. The following takes a certain type of imported positive and negative pressure vacuum blister machine as an example, using a two-component plastic absorbing machine imported from Germany to explain the entire process.

1. The working principle of the positive and negative pressure vacuum blister machine

　　Using the plasticity of the PVC film, through the adjustment and control of the film pressure time, the temperature in the equipment cavity and the air pressure, the PVC film is heated and pressurized, and the PVC is coated on the surface of the workpiece.

work process:

(1) The workpiece is placed on the workbench;

(2) The workbench enters directly below the heating plate;

(3) Close the heating plate and the workbench;

(4) The air between the heating plate and the silica gel film is drawn out, and the silica gel film is adsorbed on the heating plate to be heated;

(5) After the set time is reached, compressed air is injected between the heating plate and the silicone film, the silicone film and the PVC blister film are in close contact, the workpiece and the PVC blister film are heated, and the PVC blister film is softened, and the edge of the plate The temperature reaches the activation temperature of the glue;

(6) The air between the workbench and the PVC blister film is quickly drawn out to form a vacuum, and then compressed air is injected between the PVC blister film and the heating plate, and the PVC film is covered under the action of the set pressure and temperature. On the board.

PVC film pressing process

2　 operating procedures

　　2.1　Use requirements for plastic suction

　　 absorbing plastic is a two-component glue, the activation temperature is about 60 degrees. The storage temperature must be between 5°C and 30°C, and flocculation may occur below 5°C. The plastic bucket should not be placed directly on the ground, but should be placed on a wooden bracket, especially in winter. The validity period of the blister is 6 months from the date of leaving the factory without opening the original packaging.

　　 plastic compounding ratio main agent: curing agent = 20:1, when the main agent is mixed with the curing agent, the main agent should be kept under stirring, and the curing agent should be slowly added and stirred for at least 3 minutes. The amount of glue prepared each time should be used up within 4 hours. The plastic bucket should be tightly closed after mixing.

　　2.2　 glue spraying process requirements:

　　2.2.1　The spraying sequence is end surface-front line type-front + line type-end surface, the plane part of it can be sprayed once; the end surface and the flat line type need to be sprayed twice.

　　2.2.2” The active time after mixing the main agent and the curing agent is 4-6 hours, and the glue-sprayed workpiece should be processed within 4 hours to obtain the best bonding effect. Otherwise, the activation temperature needs to be increased due to the cross-linking reaction of the glue. Although the glue effect is good from the appearance, the temperature resistance has been significantly reduced. If the glue is sprayed twice, glue marks will appear on the surface of the PVC film.

　　2.2.3　After spraying the glue, the surface is white and dry. It is not sticky to the hand or has obvious gloss after drying. The drying time is 30-50 minutes (depending on the temperature, humidity and spray quality of the environment).

　　2.2.4　A fan is usually used 1.5-2.0 meters away from the workpiece to aim at the workpiece and blow away the moist air to avoid PVC bubbling due to high humidity of the workpiece.

　　2.2.5　 In winter, in order to increase the temperature of the workpiece, a small holding room can be used to heat the workpiece to 20-25°C (it is forbidden to exceed 35°C, otherwise the workpiece will be deformed). Glue spraying should be carried out on a water curtain machine at an environment not lower than 16°C.

　　2.2.6　 glue spraying operator should wear a mask to protect the health of the operator.

　　2.3　 Use of Silicone Film for Blister Machine

　　 According to the characteristics of the workpiece line type (such as arc value, edge angle, line width and depth, etc.), choose different thickness of silicone film.

　　Silicone film is often heated and stretched, and its sag will increase. It should be installed in time according to the degree of sag of the silicone film to reduce the sag.

　　In order to prolong the service life of the silicone film and prevent the quality problems of the workpiece, the direction of use of the silicone film should be changed regularly, such as the front end to the back end and the left end to the right end.

　　 If there are holes or short cracks in the corners of the silicone film, it can be repaired with silicone and a patching machine. When repairing, the top is compacted with a flat heavy object. After drying for 24 hours, the repaired area can be used normally with 240# sandpaper.

　　2.4　 process parameter setting

　　2.4.1” Film pressure workpiece spacing: narrow and long workpieces with a width less than 10cm, the workpiece spacing is not less than 8cm; for workpieces with a width greater than 10cm, the workpiece spacing is not less than 6cm; the spacing between the workpiece and the worktable frame is not less than 8cm. The horizontal and vertical spacing should be in a straight line to reduce air flow resistance.

2.4.2 　 Workpiece backing plate: The width and length of the backing plate should be 6-10mm smaller than the width and length of the work piece. The edges and corners around the upper surface of the backing plate should be rounded with a radius of 3mm-5mm or a 3×45°C corner. , In order to ensure that the air between the PVC film and the workpiece is completely exhausted, so that the PVC film is firmly glued to the edge of the workpiece. The thickness of the backing plate should be about 3/4 of the thickness of the workpiece, which is one of the important measures to ensure that the PVC is not drawn white.

2.4.3 　 Set temperature: According to the different PVC film, the set temperature should be between 130℃ and 160℃. The temperature of ordinary PVC film (compared to high-gloss PVC film) should be higher, and the temperature of high-gloss PVC film should be lower (avoid Loss of light due to high temperature).

2.4.4 　 Setting time: preheating time should be between 30s-50s (different PVC film color, preheating time should be different, light color should be appropriately lengthened, dark color should be appropriately shortened; thick PVC film should be appropriately lengthened , The thin PVC film should be shortened appropriately), the vacuuming time should be about 8s, and the pressurizing time should be the preheating time plus 10 to 20s. The time to reach the set pressure should not be too long, it should be about 5s to ensure that the PVC film and the substrate are quickly adhered to the substrate when the end surface of the workpiece reaches above the activation temperature, and the PVC film on the workpiece is not excessively stretched (that is, no lines are eliminated) .

　　2.4.5　 set pressure: set the positive pressure to 3.8bar－4.2b