1. PVC RESIN: The use of ethylene method five resin, good strength and toughness, environmental protection.
2. The fineness of calcium powder: because of the large proportion of calcium powder, directly affect the formula cost, processing performance and screw cylinder wear and product performance, so can not choose too thick calcium powder, calcium powder fineness to 400-800 Mesh.
3. Internal and External Lubrication: It is recommended to use high performance wax and a small amount of wax, taking into account the long residence time at high temperature in the extruder, the properties of the material and the factors of Stripping Force And the use of different wax to meet the initial and medium and long-term lubrication requirements.
4. ACR: due to the high content of calcium powder in SPC floor and the high requirement of plasticizing, besides the control of screw type and processing technology, plasticizing must be assisted by the addition of additives, and the melt has certain strength and ductility in the calendering process.
5. Toughening agent: The floor not only needs low shrinkage rate, good rigidity, but also needs certain toughness, and needs rigidity and toughness to balance each other, to ensure the firmness of the lock, not soft at high temperature, and to maintain a certain toughness at low temperature. The toughness of CPE was good, but the rigidity of PVC was decreased, the softening temperature of vicat was decreased, and the shrinkage was increased.
6. Anti-shrinkage agent: Compression PVC MATERIAL BETWEEN The particle gap to reduce the temperature caused by excessive shrinkage
7. Pe Wax is not only a lubricant, but also a dispersant, but the addition of large amount will affect the internal and external lubrication balance and melt strength, as well as increase the shrinkage of products and reduce peel force, products become brittle.
8. Return: Try to use the company's production return and after-processing of the recycling material.
Note: Clean, not wet, batch crushing blending after grinding. In particular, the split slot of the recycled material, must be proportionally blended grinding, forming a closed recycling return. It is necessary to adjust the technological formula of the sample for the great change of the amount of the return material addition.
1. Formula and weighing
Different types of weight of materials, the need to use the corresponding precision weighing device to ensure the accuracy of weighing.
Material Integration: convenient for storage, weighing, circulation and feeding, need to check the composition and accuracy of sampling. If it is automatic weighing system also need to monitor the review.
2. Mixed Storage
Feeding Order: according to the feeding way to determine the feeding order.
The automatic feeding and mixing system can be set up as follows: Filler 90 °C, treatment agent and PVC Resin 95 °C, Stabilizer Lubricant 105-110 °C, processing aid reinforcing agent 115 °C, Recycle Material 120-125 °C.
Artificial feeding: PVC RESIN + filler + small material + PVC resin + filler + PVC resin + recycle; one-time feeding, 120-125 °C feeding.
Cold Mixing: must be fully rapid cooling, prevent material deterioration, have the ability to cool to 40-45 °C.
Storage: In order to ensure the uniformity of materials, it is necessary to use a large storage tank storage and lay aside for a certain period of time to reuse.
It is necessary to test the main flow property of different batches of materials and the rheological property of the materials as a monitoring means and a basis for analysis and improvement.
Note that there are differences in mixing effect, mixing temperature and mixing time between different mixer.
3. EXTRUSION PROCESS
The setting of the processing technology not only affects the processing level, but also affects the product quality and production efficiency. It needs to be considered in combination with equipment characteristics, material properties and formula.
Relationship between extruder size and product specifications:
There is a certain relationship between the size of extruder and the size of product cross section.
For example, it is difficult to make a 4mm thick plate with a 110 extruder. First of all, at a certain extrusion speed of the large extruder, the speed of the production line is already very fast, the molding pressure is relatively high, and the requirements for the plasticization and fluidity of the materials are high. If the production depends on the gap of the open die, then the longitudinal tensile ratio is relatively large The high requirement of melt strength, and because of the tensile orientation easy to cause the vertical and horizontal shrinkage difference, resulting in excessive shrinkage and plate warping. At the same time, high-speed production for rolling joint cooling requirements are also high.
If you use 110 extrusion line production floor, the formulation process should be carefully designed and set up.
According to the current situation: 92,80 units do 4mm below the floor is more appropriate. Die Clearance is slightly larger than floor thickness.
FUSELAGE: Zone One and zone two temperature is very important, need to ensure plasticizing easy to vacuum. Too High, easy to build up in the vacuum port, generally between 185-195, other can be slightly lower.
The temperature of the confluent core has a great influence on the back pressure. The lower point is favorable for the melt moving from spiral to straight line, generally at 165-175 °C.
The mold temperature should be relatively high, in favor of small gap melt flow. Generally in 190-200 °C, at the same time combined with die clearance corresponding to adjust the thickness of uniform billet.
Extruder host speed: generally controlled at rated speed of 75-85% . The feeding speed is mainly determined by the main engine speed and the main engine (load) current.
Under the premise of the formula, the processing temperature, the main engine speed and the feeding speed match each other, so that the current is stable, the discharging surface is uniform, and there is a certain production speed.
The screw will wear out after a certain period of use. First, the processing technology can be adjusted, such as reducing extrusion speed, increasing feed speed, appropriately increasing the processing temperature of the first and second zone to reduce the temperature of the confluent core. Adjust the formula appropriately to increase the amount of ACR. If necessary, re-adjust the screw cylinder related clearance, polishing damaged parts, and adjust the process formula.
4. CALENDERING TECHNOLOGY
Under the condition of stable extrusion.
Main control: Roller Clearance, temperature, speed, as well as before and after the speed of the match.
The first pair of roller clearance and speed to determine the basic thickness of the floor, should be based on the line speed of the initial determination. Back cover roller speed a little faster, to ensure that there is a certain amount of tension, do not cause film stretching narrow is appropriate. The traction speed is such that the plate does not deform. Some adjustments should be made slowly according to the actual situation. Embossing and film sticking mainly depend on roller clearance, roller temperature, different thickness of plate, different kinds of film, different clearance and temperature, and take into account the influence of traction speed.
Roll temperature speed: should ensure normal calendering, embossing clear, stick film bonding firm, full trimming, film deformation.
Roller Temperature: 165-185 °C.
Before and after the two pairs of roller clearance, basically the same. The two need to be adjusted together.
5. Stereotypes and others
As the production process of the product has not yet fully finalized, so cutting flow to avoid stress, the carrying tray needs to be firm and smooth. Product testing also requires the substrate and finished products to be put on a certain period of time for sampling.
A brief analysis of common problems -- POOR MOLDING OF PRODUCTS
1, the product size is not stable, molding mold dissatisfaction, wall thickness is not uniform
Reasons: unreasonable internal and external lubrication formula, quantitative feed speed instability, screw bucket wear serious, with the gap is not right;
Solution: Improve the internal and external lubricant ratio, correct feed failure, replace the barrel and screw, adjust the barrel and screw clearance.
2, the Product Appearance Bright Luster is not uniform, the color deviation is obvious, the surface appears the irregular fish scale pattern;
Reasons: Irrational formula structure, inorganic filling too high, poor plasticization, insufficient amount of anti-impact materials added;
Solution: Modify the formula structure, properly reduce the inorganic filler content, modify the material plasticized to about 65% , as appropriate to increase the impact of materials.
3. The finished product is bent, deformed and Partially Sunken
Reason: The head and the mold is not in the same plane, extrusion speed is too fast, cold water temperature is too high, water pressure over small water flow is not enough, air flow is not smooth, vacuum negative pressure is not enough;
Solution: Straightening Machine head die and molding at the same level, reduce extrusion speed & Cooling water temperature, increase water pressure and flow rate, adjust vacuum negative pressure to check the water, air.