Production process of PVC plastic decorative sheet
DATE：2019/8/26 9:35:54 / READ： / SOURCE：This station
Production process of PVC plastic decorative sheet
(1) Kneading. The accurately metered resin and auxiliary agent must be kneaded. Kneading is a necessary process in PVC processing. The quality of the kneading effect directly affects the quality of the product. The main influencing factors are the amount of feed, the order of feeding, the temperature and time. Experiments show that when the feeding amount is 50%~70%, the effect is best; when the feeding amount is less than 50%, the heating rate is slow and the energy consumption is more; when the feeding amount is more than 70%, the material tumbling becomes slower, the equipment load increases, and the rotation speed Dropping is not conducive to mixing evenly. In order to make the components fully effective, the order of feeding is PVC resin, stabilizer, internal slip agent, modifier, filler, and external lubricant.
At normal temperature, the size of PVC particles is different, and it is easy to cause uneven formation during the molding process. When the temperature reaches 90 ° C -110 ° C, the particle size is large and uniform, the small particles gradually disappear, and some of the particles are partially gelled, which is favorable for plasticization during extrusion molding. In addition, the quality of kneading is also related to time.
The kneaded material must be sieved to avoid mixing impurities.
(2) Granulation and molding. Both granulation and forming use a single screw extruder. The production of PVC plastic gussets by a single-screw extruder must first be granulated to facilitate pre-plasticization of the PVC plastics, so that it is completely plasticized during molding. In the granulation and molding process, the material undergoes three-state changes, namely glassy state, high elastic state and viscous flow state, so the temperature change should meet this requirement. Among them, the temperature of the feeding section is the lowest, and then rises step by step, and finally the material enters the machine head in a fluid state. The temperature of the head must be controlled above the viscous temperature and below the thermal decomposition temperature. The temperature at the die can be slightly lower than the temperature of the head, so that there is a certain pressure in the head to promote the uniformity of the material, so that the product after molding is physically Mechanical properties meet the requirements. The head pressure is generally 8 MPa-12 MPa.
The screw speed directly determines product quality and productivity. The speed range is selected as N = (84.8 - 297) D 1/2, where D is the screw diameter and N is the screw speed.
(3) Vacuum cooling and setting. The melt extruded from the die must enter the sizing die as soon as possible, and be attached to the mold wall to cool the shape to avoid deformation, and the adsorption by the vacuum pump is attached. Since the wall thickness of the product is relatively thin, the vacuum can reach the requirement when the vacuum reaches 0.06 MPa-009 MPa. At the same time as the melt is attached, it can be rapidly cooled by the action of the staggered circulating water. In order to reduce the internal stress generated during cooling, the circulating water should enter from the end of the sizing die, and the front end is discharged, and the water temperature is preferably 10 ° C - 25 ° C.
(4) Traction. Traction is an important part of ensuring the normal production of extrusion. The tractor must have a certain amount of traction, clamping force and traction speed. The first two can generally meet the requirements, the key is to control the latter. The traction speed must match the extrusion speed and there is no fluctuation in stability. In normal production, the former is slightly faster than the latter by 1%-10% to overcome the die swell of the profile.
(5) Laminating. After the profile is cooled and set, the surface color is monotonous and colorless. In order to increase the appearance, surface coating is required. In order to make the film go smoothly, it is necessary to adjust the process parameters such as temperature, time and pressure. The temperature depends on the degree of adhesion of the color film, the color film is different, and the temperature is also different. Pressure is the necessary condition to determine whether or not the film can be covered. If the pressure is too large, the plate will be easily deformed; if the pressure is too small, the film will not be covered: at the same time, the pressure of each part should be balanced and there should be no deviation. The time is determined by the speed of the rubber roller, which has an important effect on the film.
(1) Kneading. The accurately metered resin and auxiliary agent must be kneaded. Kneading is a necessary process in PVC processing. The quality of the kneading effect directly affects the quality of the product. The main influencing factors are the amount of feed, the order of feeding, the temperature and time. Experiments show that when the feeding amount is 50%~70%, the effect is best; when the feeding amount is less than 50%, the heating rate is slow and the energy consumption is more; when the feeding amount is more than 70%, the material tumbling becomes slower, the equipment load increases, and the rotation speed Dropping is not conducive to mixing evenly. In order to make the components fully effective, the order of feeding is PVC resin, stabilizer, internal slip agent, modifier, filler, and external lubricant.
At normal temperature, the size of PVC particles is different, and it is easy to cause uneven formation during the molding process. When the temperature reaches 90 ° C -110 ° C, the particle size is large and uniform, the small particles gradually disappear, and some of the particles are partially gelled, which is favorable for plasticization during extrusion molding. In addition, the quality of kneading is also related to time.
The kneaded material must be sieved to avoid mixing impurities.
(2) Granulation and molding. Both granulation and forming use a single screw extruder. The production of PVC plastic gussets by a single-screw extruder must first be granulated to facilitate pre-plasticization of the PVC plastics, so that it is completely plasticized during molding. In the granulation and molding process, the material undergoes three-state changes, namely glassy state, high elastic state and viscous flow state, so the temperature change should meet this requirement. Among them, the temperature of the feeding section is the lowest, and then rises step by step, and finally the material enters the machine head in a fluid state. The temperature of the head must be controlled above the viscous temperature and below the thermal decomposition temperature. The temperature at the die can be slightly lower than the temperature of the head, so that there is a certain pressure in the head to promote the uniformity of the material, so that the product after molding is physically Mechanical properties meet the requirements. The head pressure is generally 8 MPa-12 MPa.
The screw speed directly determines product quality and productivity. The speed range is selected as N = (84.8 - 297) D 1/2, where D is the screw diameter and N is the screw speed.
(3) Vacuum cooling and setting. The melt extruded from the die must enter the sizing die as soon as possible, and be attached to the mold wall to cool the shape to avoid deformation, and the adsorption by the vacuum pump is attached. Since the wall thickness of the product is relatively thin, the vacuum can reach the requirement when the vacuum reaches 0.06 MPa-009 MPa. At the same time as the melt is attached, it can be rapidly cooled by the action of the staggered circulating water. In order to reduce the internal stress generated during cooling, the circulating water should enter from the end of the sizing die, and the front end is discharged, and the water temperature is preferably 10 ° C - 25 ° C.
(4) Traction. Traction is an important part of ensuring the normal production of extrusion. The tractor must have a certain amount of traction, clamping force and traction speed. The first two can generally meet the requirements, the key is to control the latter. The traction speed must match the extrusion speed and there is no fluctuation in stability. In normal production, the former is slightly faster than the latter by 1%-10% to overcome the die swell of the profile.
(5) Laminating. After the profile is cooled and set, the surface color is monotonous and colorless. In order to increase the appearance, surface coating is required. In order to make the film go smoothly, it is necessary to adjust the process parameters such as temperature, time and pressure. The temperature depends on the degree of adhesion of the color film, the color film is different, and the temperature is also different. Pressure is the necessary condition to determine whether or not the film can be covered. If the pressure is too large, the plate will be easily deformed; if the pressure is too small, the film will not be covered: at the same time, the pressure of each part should be balanced and there should be no deviation. The time is determined by the speed of the rubber roller, which has an important effect on the film.
Author：admin