Operation Process of Vacuum Plastic Suction Machine
Plate preparation
1. Check the cleaning of the surface of the plate, blow away the wood chips and fibers on the surface of the plate, and keep the surface clean and dust-free.
2, The need to paste the plate should be smooth and smooth, to avoid oil pollution, especially the corner position of the substrate and the relief pattern should be jet to blow the polishing dust.
3, When grinding the four sides of the cut sheet, the sandpaper should be used as fine as possible. In this way, after spraying glue, the four sides of the plate will not cause uneven glue absorption because the fiber is too rough, resulting in pitting phenomenon. Where the appearance of the finished product is required to be higher, it is recommended to use sandpaper with a fineness of 800 mesh or above.
Selection of composite film
1, The thickness of the composite film, softness, plasticizer content and other factors will affect the selection of blister process conditions. When the material is changed, the process conditions should be evaluated and adjusted before mass production.
2, As far as possible to choose a low plasticizer content of the film, because the plasticizer in the film in a long time storage and high temperature environment, it is possible to free from the surface, thus affecting the bonding effect.
3, For hard PVC film, it is recommended to use a shorter blister time, and a higher blister temperature;
4, For soft PVC film, it is recommended to use a longer blister time, and a lower blister temperature;
5, PVC plastic film is useful in flat paste and vacuum blister two types, not all films are suitable for vacuum blister. Usually, the thickness of the film used for flat paste is below 0.25mm, which is not heat resistant and has large shrinkage. The thickness of the film used in vacuum blister is above 0.25mm, heat resistance and small shrinkage.
6, Most of the PVC film with the back coating treatment, the surface tension reached 34-36dyn/cm.
Selection of plates
1. The general requirement is to control the moisture content of MDF between 6% and 14%.
2, The moisture content of the plate is 8-12%.
Use of curing agents
1. Under normal circumstances, the polyurethane emulsion single component in the vacuum suction plastic has a strong adhesive force after thermal activation, which can meet the performance requirements of the finished product.
2, Adding the appropriate proportion of curing agent can improve the high temperature resistance, water resistance and adhesion of the finished product.
3, If the customer's heat resistance requirements for finished products exceed 70 ° C, or the temperature and humidity of the production workshop are too high, it is recommended to add curing agent.
4, The amount of curing agent in the suction plastic 3%-5% is appropriate; The ratio of main agent to curing agent should be accurately weighed.
5, The main agent and curing agent should be mixed evenly, it is recommended to use electric stirring, mixing time is not less than 2 minutes.
6, The mixed adhesive is required to be used within 8 hours.
7, Curing agent should be stored in a cool and dry place, storage temperature at 10-30℃ is appropriate.
8, The main agent and curing agent should be used as soon as possible after opening the barrel.
Glue quantity
1, The amount of gluing water varies according to the material of the wood, the glue evenly covers the surface of the board after the wood glue suction, under normal circumstances, the plane spray amount of 40-80g/m2, the surface, cross section, relief contour spray amount of 80-100 g/m2 (it is recommended to spray twice to achieve a better bonding effect). In addition, the amount of glue should be adjusted according to the thickness of the PVC film.
2, Spray gun caliber: It is recommended to use 1.5-2.0mm caliber spray gun. Spray gun pressure: 0.5-0.8MPa, the spray gun should be adjusted to large gas flow, good atomization effect, less glue, fan spray.
Blister method
1, Drying time: according to the temperature, humidity and glue drying speed and other conditions, generally after spraying glue should be left to dry for 10-30 minutes in order to penetrate and evaporate the water in the glue, especially in the position of thick spraying glue, need to wait until the glue dries into a film, so as to avoid the local moisture content is too high during blister heating to cause foaming or adhesion is not strong. However, do not use hot air such as hair dryer to accelerate drying.
2, The blister method is divided into dry blister and wet blister two ways;
3, Dry blister: After the adhesive is dried, then enter the machine for blister to become dry blister, generally at room temperature of 25℃, the drying time of glue is 20-30 minutes. At 40℃, the drying time of glue is 5-10 minutes. It is recommended that customers carry out blister under the condition that the film is completely transparent and has no white marks. However, the drying time is too long, which may affect the bonding effect. Especially for the occasion of adding curing agent, the drying time should be shortened as much as possible.
4, Wet blister: adhesive in the wet state, the adhesive is not completely dry into the machine blister called wet blister. Wet blister is mainly used for the customer's equipment can not reach the lowest activation temperature of the adhesive or the composite film temperature resistance is very poor, because the adhesive in the blister process water is not completely volatilized, therefore, the blister time is longer than dry blister. Under normal circumstances, try not to use wet composite, especially the blister operation with short heating time. Otherwise, the finished product may slip glue.
Minimum activation temperature
1, Activation temperature: according to the different products, the activation temperature of plastic is generally 50-60 ° C, the temperature of the film generally needs to reach more than 60 ° C in order to activate completely, the adhesive strength of the glue can achieve the best.
2, Under normal circumstances, the higher the blister temperature, the more conducive to the infiltration of the film on the surface of the composite film, and the bonding effect is favorable. However, at the same time, it is necessary to consider the heat resistance of the composite film to avoid breaking the film.
3, The required minimum activation temperature is the lowest temperature of the glue to reach the crosslinking and bonding, the plastic process, the glue temperature must be higher than the minimum activation temperature specified in the product manual, otherwise it will lead to insufficient activation, seriously affecting the adhesion effect of the finished product.
Vacuum degree
1, The vacuum depends on the different suction equipment, the model and thickness of the composite film, the suction temperature, the profile of the plate surface, the placement of the plate, etc., customers should adjust according to their actual situation.
2, Under normal circumstances, according to the empirical value, for 0.16mm-0.20mm thick PVC film, under the condition of 110-140℃ set temperature of the machine, the vacuum degree is recommended to be -0.07 to -0.09MPa.
Vacuum time
1, The vacuum time depends on the hardness of the composite film, suction temperature, plate profile, vacuum, etc., customers should make corresponding adjustments according to their actual situation.
2, Under normal circumstances, according to the empirical value, under the conditions of ensuring that the blister temperature reaches the lowest activation temperature of the adhesive and the composite film is fully softened, the vacuum time is 10-30 seconds.
Stress
1, For positive pressure suction equipment, in the vacuum, the upper molding bin will inject hot air to form high pressure, to ensure that the composite film close to the MDF, the size of the pressure depends on the suction temperature, film thickness, plate profile, vacuum degree, etc., customers should make corresponding adjustments according to their actual situation.
2, according to experience, the pressure is usually about 0.2-1.8MPa.
3, For the non-positive pressure suction equipment, only vacuum when suction, no positive pressure, in order to ensure the effect of suction. The vacuum degree should be increased accordingly.
4, For wet blister, the recommended time is 3-5 minutes, for dry blister, the recommended time is 2-3 minutes.
Gun caliber
1, Under normal circumstances, the spray gun caliber is 1.5-2.5mm.
2. When the gun diameter is less than 1.0mm, it is easy to block the nozzle during operation, affecting the work efficiency; The diameter of the spray gun is greater than 2.5mm, the glue atomization effect is poor, the spray pellets are too large, and the pitting phenomenon is easy to occur.
Protection time
1, Usually blister good finished products, out of the machine can be transported.
2, If the processing of the next process is needed, it is best to wait for the finished product to be completely cooled.
3, If the performance test of the final product is carried out, it is recommended to keep healthy for more than 2 days.
