Chinese name: chlorinated polyethylene

English name: Chlorinated Polyethylene

Structural formula: [CH2-CHCl-CH2-CH2 ]n

English abbreviation: CPE or CM

Chlorinated polyethylene (CPE) is a saturated polymer material, white powder in appearance, non-toxic and tasteless, with excellent weather resistance, ozone resistance, chemical resistance and aging resistance, and good oil resistance, flame retardancy and coloring performance. Good toughness (flexibility at -30℃), good compatibility with other polymer materials, high decomposition temperature, decomposition to produce HCl, HCL can catalyze the dechlorination reaction of CPE. Chlorinated polyethylene is a polymer material made from high-density polyethylene (HDPE) through chlorination substitution reaction. According to different structures and uses, chlorinated polyethylene can be divided into resin-based chlorinated polyethylene (CPE) and elastomer-based chlorinated polyethylene (CM). In addition to being used alone, thermoplastic resins can also be blended with resins such as polyvinyl chloride (PVC), polyethylene (PE), polypropylene (PP), polystyrene (PS), ABS, and even polyurethane (PU). In the rubber industry, CPE can be used as a high-performance, high-quality special rubber, and can also be combined with ethylene propylene rubber (EPR), butyl rubber (IIR), nitrile rubber (NBR), chlorosulfonated polyethylene (CSM), etc. Other rubber blends for use.

Development History

In the 1960s, the German Hoechst company first successfully developed and realized industrialized production. my country began to develop chlorinated polyethylene in the late 1970s. It was first developed by the Anhui Research Institute of Chemical Industry to successfully "Synthesize CPE Technology by Aqueous Suspension Method", and successively built 500-1000t/a production facilities of different scales in Wuhu, Anhui, Taicang, Jiangsu, and Weifang, Shandong. In the early 1990s, Shandong Weifang Chemical Plant imported 6000t/a CPE complete production equipment from Germany. At the beginning, it produced resin-based chlorinated polyethylene, which was mainly used as an impact modifier for PVC and a flame retardant modifier for engineering plastics such as ABS. In China, Yaxing Chemical (Weifang) has an annual output of 120,000 tons of rubber resin type CPE. It is the largest manufacturer of chlorinated polyethylene in Asia. Its product performance is stable and excellent. The product name is Weiprene, and the main brands are 135A, 135B etc. Internationally, Dow Chemical took over the original DuPont Elastomer (DDE) chemical CPE production line at the end of 2005. The performance is very good. The trade name is Tyrin. The main product brands are Tyrin CM0136 and Tyrin CM Characteristics of ethylene.

1) CPE is a saturated rubber, which has excellent resistance to heat and oxygen aging, ozone aging, acid and alkali resistance, and chemicals.

2) CPE has excellent oil resistance. Among them, it has excellent resistance to ASTM No. 1 oil and ASTM No. 2 oil, which is equivalent to NBR; and it has excellent resistance to ASTM No. 3 oil, which is better than CR and is equivalent to CSM.

3) CPE contains chlorine element, has excellent flame retardant properties, and has the characteristics of burning and dripping. It can be combined with antimony flame retardant, chlorinated paraffin, and Al(OH)3 in an appropriate ratio to obtain a flame retardant material with excellent flame retardancy and low cost.

4) CPE is non-toxic, does not contain heavy metals and PAHS, and it fully meets environmental protection requirements.

5) CPE has high filling performance and can produce products that meet various performance requirements. The processing performance of CPE is good, and the Mooney viscosity (ML121 1 4) is available in a variety of grades between 50-100.

The main purpose

At the end of the 1990s, the domestic demand for high-performance flame-retardant rubber increased, especially the development of the wire and cable industry and auto parts manufacturing industry, which drove the consumer demand for rubber-based CPE. Rubber CPE is a special synthetic rubber with excellent comprehensive performance, heat-resistant oxygen ozone aging, and good flame retardancy. Mainly used in: wire and cable (cables for coal mines, wires specified in UL and VDE standards), hydraulic hoses, automotive hoses, tapes, rubber sheets, PVC profile pipe modification, magnetic materials, ABS modification, etc.

Application coordination technology

1) Reinforcing filling system

CPE is a non-self-reinforcing rubber, and it needs a reinforcing system to achieve better strength. Its reinforcing and filling system is similar to general rubber. The reinforcing agent is mainly carbon black and white carbon black. White carbon black can improve the tear resistance of CPE, and can form a meta-white system to improve the adhesion between CPE and the skeleton. . CPE has high filling properties, and the filling system mainly includes calcium carbonate, talcum powder, clay and so on.

2) Plasticizing system

Ester plasticizers are the most commonly used plasticizers for CPE, such as dioctyl phthalate (DOP) and dioctyl adipate (DOA). Their solubility parameters are close to those of CM and their compatibility is good. DOA and DOS are used in rubber compounds to give them excellent cold resistance.

3) Stable protection system

When CPE is heated or vulcanized (non-peroxide vulcanization system), hydrogen chloride will be released. Therefore, stabilizers with acid absorbing effect should be used in the formulation, such as calcium stearate, barium stearate, tribasic lead sulfate or Magnesium oxide.

4) CPE curing system (important)

CPE is a saturated rubber, and the general common sulfur vulcanization system cannot effectively cure it. The thiourea system is the earliest application of CPE curing system, the most effective of which is Na-22, but Na-22 has slow curing speed, poor aging performance, high compression set, and Na-22 is a serious carcinogen. Produces an unpleasant smell, and its use abroad has been restricted.

At this stage, the more mature application of CM curing system is the peroxide curing system, which has a faster curing speed, good product physical properties, and small compression set. Peroxide is not suitable for moldless vulcanization under lower pressure. The peroxide system can be used in the production of adhesive tapes, with good physical properties, heat and oil resistance. When the system is matched, adding auxiliary crosslinking agents such as TAIC, TAC, TMPTM, HVA-2 can significantly improve its physical and mechanical properties and heat resistance. Since peroxide is a free radical reaction to produce cross-linking, some acidic fillers will affect the generation of free radicals, so this type of filler should not be used.

EataMix TCHC is a compound type CPE special vulcanizing agent. The product is non-toxic. It was introduced into China by Shanghai Youlun Chemical to meet domestic needs.

TCHC can use cheap aromatic oil as a plasticizer, and the vulcanizate has excellent properties. The activity of MgO has little effect on the physical properties and aging properties of the vulcanizates of the TCHC system. Ultrafine Mg(OH)2 used as an acid absorbent is equivalent to the highly active magnesium oxide with an iodine absorption value of 150, which can replace the expensive imported highly active magnesium oxide. Greatly reduce manufacturing costs. The application cost is much lower than that of foreign thiadiazole systems, and it can be applied to various vulcanization processes, including lower temperature, moldless, pressureless and low pressure vulcanization. This kind of system has fast vulcanization speed, excellent physical properties of vulcanized rubber, low compression set, good resistance to heat and oxygen, ozone aging, and oil resistance. It is also an effective crosslinking system for CPE and diene rubber. Successfully applied in the hose industry. The vulcanization speed of TCHC is slower than that of peroxide, but it can be vulcanized under lower temperature, no pressure and no mold, and the vulcanizate has excellent properties.

In recent years, the American GEO company and German Rhein Chemie introduced a new thiadiazole vulcanization system, which is combined with amine accelerators and has a good vulcanization effect. However, the chemical composition of this system is not disclosed, and the price is high, so domestic promotion is slow. The thiadiazole system mainly consists of a crosslinking agent and an accelerator. The main crosslinking agents are ECHO.A, ECHO.MB, and TDD. The main accelerators are Vanax 808, EataAccel DH, NC. It is a kind of promising additives.