Extrusion composite process
DATE：2022/5/19 9:04:45 / READ： / SOURCE：This station
Extrusion composite process
In the production process of extrusion compounding, the base material is fed between the double silicon cots, and the molten mucosa is extruded from the die mouth of the die head and coated on the base material. Under the pressure of the double steel roll, the molten mucosa is compounded with the base material, and the cylindrical composite material is obtained by traction and winding. High speed breathable film production line www.handern.com com1、 Preparation for startup
(1) whether the material and base meet the quality requirements. The moisture content of raw materials shall be controlled and shall not be mixed with metal, sand and other impurities. The base material shall be clean and free of oil, dust and hard blocks, so as not to affect the composite quality and damage the silicone roll.
(2) Knives, gloves and other special production tools.
(3) Check whether the three-phase voltage of the power supply is balanced and normal. High speed breathable film production line www.handern.com com
Production process of extrusion composite
1 - first base material 2 - unwinding roller 3 tension iron roller 4 - tension roller 5 - preheating roller 6 die 7 - second base material 8 - washing powder solution tank 9 - cooling steel roller 10 - silicone roller 11 - cooling roller 12 - conveying roller 13 - composite film roll 14 - third base material
(4) Check the connection tightness of each equipment, the lubrication of sprocket, gear and bearing, and adjust the tightness of chain and belt to ensure that the machinery rotates flexibly and operates normally.
(5) Check whether the outgoing machine, magnetic particle brake, cooling steel roller, silicone roller, etc. rotate normally.
(6) Turn on the main power supply, check whether all electrical controls are normal and whether each section of heater works normally, and adjust each heating controller to the following temperatures: 160 ℃, 220 ℃, 230 ℃, 245 ℃, tee 250 ℃ and connector in zone 1 ~ 4 of barrel respectively
250 ℃, 260 ℃ for double die. The above temperatures need to be changed and adjusted according to different equipment and raw materials. High speed breathable film production line www.handern.com com
(7) Add the raw materials into the drying mixer for mixing. The drying temperature is about 50 ℃. If there is recycled material in the resin, set the mixing temperature of recycled material at 45 ~ 80 ℃ for 3 ~ 5min, and then add new material to continue mixing.
(8) Fill the washing powder solution tank with water until the composite roller is immersed in the solution for 20mm, and add washing powder (700g washing powder in each tank) into the washing powder solution to stir and dissolve.
(9) Install the base material on the reel and walk through it according to the route of the base material flow chart. Start the automatic deviation correction mechanism and adjust the deviation correction position to align the substrate with the substrate.
(10) When material winding is required, install the paper core on the winding shaft.
(11) When the die temperature reaches 230 ℃, adjust the adjusting rod blocks at the discharge ports at both ends of the die according to the width of the substrate, so that the discharge port of the die is about 80mm wider than the substrate, and the length of the discharge ports of the two dies must be the same and symmetrical.
(12) Adjust the die gap. Generally, the die gap is between 0.5 ~ 0.6mm. The gap can be measured with a feeler gauge, and the die gap of the two die heads and the full length of the die head shall be uniform.
2、 Operation steps
(1) Add resin to the hopper.
(2) When each heating zone reaches the process temperature and the temperature is kept constant for 15min, turn on the extruder motor, slowly speed up the screw speed, and pay attention to the indication of ammeter. If it is abnormal, shut down the machine quickly for emergency repair to avoid damaging the screw. Turn on the motor after troubleshooting.
(3) After the molten resin is extruded from the die, a 0.4mm thick brass sheet can be used to scrape on the die to remove coke, slag inclusion and local blockage.
(4) Until the film blank extruded from the die is clear (generally 5 ~ 15min).
(5) Start the motor of the compound device, run at a low speed, close the silicon rubber roll and steel roll and adjust the pressure, pass the substrate passing through the middle of the double die into the compound rubber roll in advance, pull it out by the guide synchronous pressing roll, wind it on the winding shaft through the guide roll, or enter the punching machine and cutting machine. (6) Start the deviation corrector of winding device and unwinding device and all motors used
(7) Move the host to the composite location.
(8) Put the base material of the left and right unwinding devices of the compound machine into the compound cot and make it compound with the base material in the middle.
(9) Open the cooling water valve to cool the cold steel roll.
(10) When the machine is running normally, speed up the screw speed of the extruder and the compound speed of the auxiliary machine and the speed of the auxiliary machine required to be normal.
(11) Check the width, thickness and composite fastness of the product and make corresponding adjustments.
(12) During normal operation, prepare the roll change work of winding and winding.
(13) Emergency shutdown: when emergency shutdown is required in case of accident, turn off the main air switch, and then the extrusion, compounding, punching and cutting motors stop running.
(14) Normal shutdown:
① 15 min before shutdown, cut off the heating power supply of die head, connector and preheating roller. ② During shutdown, cut off the heating power supply of each area and tee of the extruder, and slow down the extrusion motor.
③ Stop the extruder and exit the working position, and stop the compound motor
Turn.
④ Cut off the substrate and disconnect the composite silicon rubber roller and cooling steel roller. ⑤ Turn off all drive motors. ⑥ Turn off the cooling water valve of the steel roller.
⑦ Clean the equipment and workplace and tidy up the tools. High speed breathable film production line www.handern.com com
(15) Replace the filter screen. The time for replacing the filter screen shall be determined according to the actual situation. The resin is brand-new material, which shall be replaced once every three days, and the longest shall not exceed one week. If there is recycled material in the resin, it depends on the proportion of recycled material in the new material and the cleanliness of recycled material. Generally, it is replaced once a day. When replacing the filter screen, it must be carried out under the condition that the screw does not rotate and the tee and extruder are still heated. Pay attention to the following when replacing the filter screen:
① Put on gloves, loosen the screws on the tee cover with the handle and take out the tee cover
② Open the filter screen with a screwdriver, clamp the filter screen with pliers and take it out. After burning the plastic on the filter screen, it can be used more than 20 times.
③ Scrape the oxidized coke material in the tee and on the filter plate with a scraper.
④ Install the cut disc-shaped filter screen in the tee. Generally, 5 ~ 18 pieces of 0.30mm filter screen shall be placed, and steel wire screen can be used.
⑤ Install the tee cover and tighten the screws on the tee. Note that the upper screws must be diagonal to ensure parallelism.
3、 Key points of Technology
1. Extrusion temperature of extruder
Different plastic resins should adopt different extrusion temperatures. The heating temperature is directly related to the quality of coating materials, especially the die temperature. The temperature is too low, resulting in poor plasticization, which reduces the transparency and surface gloss of the product; Even defective products such as fish eye blisters and shark skin; Poor composite fastness. If the temperature is too high, the plastic is easy to decompose, the product is brittle and hard, the shrinkage of extrusion film increases, and the heat sealing property becomes poor.
2. Melt flow rate and density of resin
Melt flow rate is an index of resin fluidity. The melt flow rate is the mass (g) of the resin melt passing through the standard capillary tube for 10min under a certain temperature and pressure. The unit of melt flow rate is g / 10minc
The higher the melt flow rate of the resin, the better the fluidity, the lower the viscosity of the molten film and the greater the adhesion. In addition, the resin has low density, high branched chain content, easy surface activation and poor adhesion.
3. Air gap
Air gap refers to the distance from the die lip to the contact line between the two composite rollers. The air gap is large, the heat loss of the hot film is large, and the coating fastness is poor when the temperature at the contact point with the substrate is low. Generally, the air gap distance is controlled between 50 ~ 150mm. In addition, the air gap distance is large, and the necking of hot film blank is also large. High speed breathable film production line www.handern.com com
4. Cooling roll temperature
The surface temperature of the cooling steel roller is low, the cooling speed is accelerated, the transparency of the coating layer is increased, but the composite strength will be reduced; The surface temperature of the cooling steel roller is high, the cooling is slow, and the opening becomes worse. Generally, the surface temperature of cooling steel roller shall not exceed 60 ℃, and it is best to control it at about 30 ℃. In addition, the hot-melt film blank is best to contact the substrate first, which will help to improve the composite strength.
5. Double sided printing substrate
One time composite treatment of double-sided printing substrate. When the substrate is a double-sided gravure printing pattern, the products that need to be compounded at one time should be installed with an electric eye tracking device on the left and right of the compounding device to control the surface tension of the unwinding substrate to adjust the synchronous compounding of the left and right substrates. In addition, the following simple methods can also be adopted:
(1) Adjust the extrusion temperature of die heads on both sides to make the flow rate of extruded hot-melt film blank the same. (2) Align and align the color printing film on both sides, paste adhesive paper, and paste it on the substrate passing through the middle of the double die.
(3) Install a handwheel with a diameter of about + 350mm at one end of the film reel mandrel of the color film unwinding device facing upward.
(4) An incandescent bulb or fluorescent tube is installed outside the guide roller to reflect the regular label of the color film compounded below.
(5) An operator shall keep an eye on the upper and lower regular marks, and use the hand wheel on the unwinding mandrel to adjust the surface tension of the substrate facing upward to achieve the pattern alignment on both sides.
In the above operation, there will be errors in the double-sided printing pattern, which can be used for products with large length and good transparency.
Author：admin