Company News

• Losses caused by low-quality CPE in PVC processing

  2024 / 03 / 25

  Chlorinated polyethylene (CPE) is a chlorinated modification product of high-density polyethylene (HDPE). As a processing modifier for PVC, the chlorine content of CPE should be between 35-38%. Due to its excellent weather resistance, cold resistance, flame resistance, oil resistance, impact resistance (CPE is an elastomer), and chemical stability, as well as its good compatibility with PVC, CPE has become the most commonly used impact toughening modifier in PVC processing. The performance of CPE is determined by two factors: 1. Molecular Configuration of HDPE Due to the different process conditions during the polymerization reaction of PE, there are certain differences in the molecular configuration and properties of its polymer HDPE. The properties of CPE after chlorination of HDPE with different properties also vary. CPE manufacturers must choose suitable HDPE special powder resins in order to produce qualified CPE resins. 2. Chlorination conditions, i.e. chlorination process CPE, as a PVC processing modifier, is usually formed by chlorination reaction using aqueous suspension chlorination method. The key conditions of this chlorination process are light energy, initiator dosage, reaction pressure, reaction temperature, reaction time, and neutralization reaction conditions. The principle of PE chlorination is relatively simple, but the chlorination mechanism is more complex. Due to the relatively small investment in equipment for producing CPE, many rudimentary small CPE production plants are already scattered throughout China. This not only causes pollution to the ecological environment, but also is one of the important reasons for the instability of CPE quality. At present, there are a large number of low-quality CPE on the market. Generally, there are two types of low-quality CPE. One is due to some production plants not having the technical conditions and outdated chlorination processe

• Common problems of PVC sheets

  2024 / 03 / 21

  The vertical thickness deviation of PVC sheet is large ① The temperature control of the barrel is unstable, resulting in unstable melt flow rate. The temperature of the barrel should be adjusted to stabilize it. ② The unstable screw speed leads to unstable extrusion volume. The process parameters of the extruder should be adjusted to ensure stable extrusion. ③ The roller speed in the three roller calender is unstable. The speed of the three roller calender should be adjusted. ④ The traction speed is unstable, fluctuating fast and slow. The traction speed should be adjusted to ensure smooth operation. Uneven lateral thickness of PVC sheet ① The design of the molding mold is unreasonable, and the fabric flow in the cross-section is uneven. The mold should be modified to ensure even discharge from the mouth mold. ② The adjustment of the gap between the mold lips is unreasonable and uneven. The middle gap should be slightly smaller than the gap on both sides. ③ The gap deviation between the three rollers of the three roller calender is relatively large, and the gap between the three rollers should be made even. ④ The height selection and processing of the three rollers are unreasonable. The height of the roller surface should be appropriately adjusted. The surface of PVC sheet is rough and lacks luster ① Rough or sticky material on the three roll working surface. The working surface of the three rollers should be cleaned and polished to achieve a smooth surface. ② The roller temperature of the calender is too low, and the temperature of the three rollers should be appropriately increased. ③ The surface of the mold lip is not smooth and should be cleaned. ④ The filter screen is broken and should be replaced with a new one. The surface of the board has horizontal lines ①

• methods to improve the hardness of PVC pipes

  2024 / 03 / 18

  How to improve the hardness of the PVC pipe produced if it cannot meet the standard? Mainly considering raw materials and formulas. Please refer to the following for details: 1. The precipitation volume of filling material (calcium powder) should preferably be within 2.6-3.0. To balance both hardness and tear strength, calcium powder should not exceed 25 parts. In addition, an appropriate amount of nano calcium can be added to improve the strength; 2. The selection of stabilizers is crucial. Stabilizers (lead salt stabilizers, calcium zinc stabilizers, etc.) should have good thermal stability and stable internal and external lubrication balance. Do not use stabilizers that are too cheap 3. If the stability is insufficient, a small amount of metal soap can be compensated; 4. The amount of CPE used should not be too large, as excessive CPE usage can affect the hardness of the pipe; CPE should be selected with high molecular weight, standard chlorine content, no more than 35%, and no residue; 5. Lubricants cannot be used too poorly, they must be good, and PE wax is the worst for external lubrication. The total dosage is about 1.5 parts, not too much, so that when the product deforms under external forces, the PVC molecular chain connection is not easily damaged; 6. In terms of modification, CPE+ACR system, ACR+MABS system, or CPE+MABS system can be selected. 7. Titanium dioxide can affect tear strength, so it is recommended to choose a fine one. We have done chemical products for nearly 30 years. Our main products include PVC RESIN, CPE, STABILIZER, TIO2, PE WAX, PARAFFIN WAX etc.