Indoor SPC floor and WPC floor formulation and extrusion process
Indoor SPC floor and WPC floor formulation extrusion processSince the outbreak of the "poisonous floor" incident in the United States, the United States has continuously raised the threshold for wood products imports in recent years. However, the plastic floor WPC that came into being combines the waterproofness and stability of LVT, and the foot feel and sound insulation effect will be more comfortable than the LVT lock floor. Today, Lai talks about the difference between the extrusion process of indoor SPC floor and WPC floor formulations. The American magazine "floorcoveringNEWS" praises WPC wood-plastic flooring in an unabashed way. The July 2017 issue introduced the past and present of WPC wood-plastic flooring and the latest fashion trends. Since the outbreak of the "poisonous floor" incident in the United States, In recent years, the United States has continuously raised the threshold for wood products imports. However, the plastic floor WPC that came into being combines the waterproofness and stability of LVT, and the foot feel and sound insulation effect will be more comfortable than the LVT lock floor. Today, Lai talks about the difference between the extrusion process of indoor SPC floor and WPC floor formulations.
The American magazine "floorcovering NEWS" praises WPC wood-plastic flooring. The July 2017 issue introduces the past and present of WPC wood-plastic flooring and the latest fashion trends. Winning a new round of explosive development opportunities. The magazine also mentions the latest SPC (Stone plastic compostic) stone plastic floor, also known as RVP (Rigid vinyl Plank), which is a new environmentally friendly floor developed based on high technology. Simple installation and other features have gradually become the new darling of the European and American markets.
The main differences between SPC and WPC floors are:
SPC floor is a high-calcium non-foaming product, the filling of calcium carbonate is 250-300 parts and the density is 2-2.1, WPC floor is a foaming product with a density of 0.85-0.9, and its filling is 80-100 parts. The comparison between SPC and WPC floors has its own advantages. SPC has a high specific gravity and high weight. The processing process is simple and the dimensional stability is excellent. WPC floor foam products have high requirements for the extrusion process and the shrinkage stress problem is difficult to control, but the formula cost is light and the proportion is light. .
Analysis of common problems-poor product molding
1. The product size is unstable, the mold is not full, and the wall thickness is uneven
Reasons: Unreasonable internal and external lubrication of the formula, unstable quantitative feeding speed, severe wear of the screw barrel, and incorrect fit clearance;
Solution: Improve the ratio of internal and external slip agent, correct feeding failure, replace the barrel and screw, and adjust the gap between barrel and screw.
2. The appearance of the product is uneven, the color deviation is obvious, and irregular fish scales appear on the surface; the product performance is poor; the toughness is poor, the product is brittle and the impact resistance is not qualified;
Reason: The formula structure is unreasonable, the inorganic filling is too high, the plasticization is poor, and the amount of impact material is insufficient;
Solution: Modify the formula structure, appropriately reduce the content of inorganic fillers, correct the plasticization of the material to about 65%, and increase the impact resistance material as appropriate.
3. The output of the finished product is curved, deformed, and partially subsidence;
Cause: The machine head and the shaping die are not on the same plane, the extrusion speed is too fast, the temperature of the cold water is too high, the water pressure is too small, the water flow is insufficient, the water and gas path is not smooth, and the vacuum negative pressure is insufficient;
Solution: Straighten the head die and the shaping die at the same level, reduce the extrusion speed & cooling water temperature, increase the water pressure and flow rate, adjust the vacuum negative pressure to check the water path and air path are unobstructed.
Problem discussion
Due to the complexity of the PVC foam product process formulation system, it is difficult to control. As a key point, we discuss with friends:
1. The plates and wallboards do not foam, first look at whether the lubrication is balanced. Generally, if the external sliding is added too much, it will not cause foaming. Adjust the amount of external sliding agent to achieve a balance. In the above formula, I added calcium stearate for the purpose It is to adjust the balance of internal and external lubrication. Calcium stearate is a heat stabilizer and a slip agent with both internal and external lubrication. It can play the role of internal and external lubrication interchangeable in the formula. Side to reach the balance of internal and external lubrication. The second is whether the amount of regulator and foaming agent is added in place, and the addition of an appropriate amount of foaming effect will meet the requirements. Once again, it depends on whether the current of the host machine reaches the normal current of our host machine, that is, the current of the 51 cone double extruder is 21-25A, the current of the 55 cone double extruder is 28-32A, and the current of the 65 cone double extruder is 42- 45A, 80 cone double extruder current is 72-78A, 92 cone double current 125-135A. If it can't reach it, it is necessary to increase the feed rotation speed, increase the current of the host, and let the material plasticize. On the contrary, if the current is large, the feed is reduced, and the current of the host meets the above requirements.
2. The surface of the board and wallboard is not smooth, the temperature is too high or the moisture of our filling material is heavy, and the weight of water will also affect the foaming state of the product, adjust the temperature or check whether the filling material has moisture.
3. The sheet and wallboard are not straight: ① Left and right are not straight, check whether the left and right positions of the mold cavity are in a line; warp up and down to see whether the mouth model cavity and the stereotyped model cavity are up and down on the horizontal line. ②The cooling is not enough. Check whether there is something blocked in the water inlet of the mold and clean it. ③The material is not evenly discharged from top to bottom, left and right, adjust the temperature or repair the mold.
4. Cracks in the plate and wall board. Check whether there is water in the wall board or there is something blocked in the water inlet of the mold. The water temperature of the mold is too high to cool down or adjust the formula.
5. Plates and wallboards are easy to paste, the machine screw shear is too large, and the internal lubrication is much, adjust the formula lubrication system or add high temperature wax.
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