Polychloroprene Rubber CR2442

Chloroprene rubber adhesive is the largest and most widely used variety among rubber adhesives. It can be sorted into a few groups, like resin modified, filler, grafted, and latex types. Grafted chloroprene rubber adhesive, which is made mostly of chloroprene rubber and a grafted modifier, is known as easy to their usage, strong bonds, high initial adhesion, and many uses. As early as the 1950s, the shoemaking industry began to use chloroprene rubber adhesive. As shoemaking materials and styles change, standard chloroprene rubber adhesive may not be strong enough. This can cause the upper and sole of shoes, or composite soles, to separate. This issue harms shoe quality and limits growth in the adhesive shoe business. To solve this problem, we used a variety of graftable chloroprene rubbers at home and abroad as graft bodies and used MMA to study their grafting modification.   1 Grafting mechanism     2 Experimental part   2.1 Raw materials and polymerization formula   2.2 Polymerization Procedure Add CR to the solvent. Heat the solution to 50 °C and stir until the CR is completely dissolved. Raise the temperature to 80°C, and slowly add the MMA solution that contains BPO while stirring. Maintain the temperature and continue stirring until the viscosity reaches a suitable level (about 40 minutes). Immediately add hydroquinone to stop the reaction. Keep warm for 4 to 6 hours. After the reaction is complete, cool down to 40°C; add thickening resin, vulcanizing agent, antioxidant and filler, and finally keep warm for 2 to 3 hours, cool down to room temperature, and obtain the product. A small amount of toluene can be added to adjust the viscosity. The obtained graft copolymer (CR-MMA) is a brown-yellow transparent viscous liquid. The viscosity measures between 1000 and 1500 mPa·s. Solid content ranges from 15% to 25%, and the strength registers at 34 N/cm².   2.3 Product analysis 2.3.1 Determination of adhesive viscosity The viscosity value (mPa·s) was tested in a 25℃ constant temperature water bath using a rotary viscometer (Shanghai Optical Factory, NDI-1 type). 2.3.2 Determination of adhesive solid content The film after vacuum drying and constant weight of the adhesive was wrapped with filter paper and placed in a fat extractor. It was extracted with acetone in a 65℃ constant temperature water bath for 48 hours (to remove PMMA homopolymer in copolymerization). The solid content (W%) was calculated according to the following formula: W %=W2 / W1×100% Wherein, W1 is the mass of the grafted adhesive, and W2 is the mass of the film after vacuum drying and constant weight. 2.3.3 Determination of peel strength of artificial leather/artificial leather (PVC/PVC) bonded by adhesive The soft PVC sheet was wiped with acetone or butanone to remove the oil stains on the surface. The entire process was in accordance with GB7126-86.   3 Results and discussion   3.1 Solvent selection The solvent used in chloroprene rubber adhesive is very important. It affects the solubility of chloroprene rubber, the initial viscosity of the adhesive, stability, permeability to the adherend, bonding strength, flammability and toxicity, etc. Therefore, the selection of solvents should take into account many factors. Commonly used solvents include toluene, ethyl acetate, butanone, acetone, n-hexane, cyclohexane, solvent gasoline, etc. The test confirmed that when the solvent cannot dissolve chloroprene rubber alone, two or three solvents can be mixed in appropriate proportions to have good solubility, viscosity and low toxicity.     3.2 Effect of CR type and concentration on the performance of grafted products Different types of chloroprene rubber (CR) show differences in how quickly they form crystals and how deep their colors are. These factors can change how well the grafted materials initially stick together and how they look. Tests show that using Denka A120 Chloroprene rubber and Chloroprene Rubber SN-244X to graft chloroprene rubber results in good initial adhesion and color. The amount of CR does not change peel strength much, but it does affect how well copolymerization works. When the CR concentration is too high, that is, the viscosity is high, MMA is difficult to diffuse and has a strong tendency to self-polymerize. Maintaining the appropriate CR concentration is necessary; if it's too low, the MMA volume will be too small, which slows down the grafting copolymerization. CR concentration works best between 11% and 12%.   3.3 Effect of reaction time on the performance of grafted products Generally speaking, the longer the reaction time, the higher the grafting rate and viscosity value. At the beginning, the initial and final adhesion strengths increase with the extension of reaction time and the increase of viscosity. Extended reaction times coupled with high viscosity can actually reduce both initial and final adhesion. Experiments suggest reaction times should ideally fall between 3.0 and 5.0 hours.   3.4 Effect of reaction temperature on grafting reaction When the reaction temperature is lower than 70℃, the reaction is slow, which is due to the slow decomposition of BPO. Because BPO decomposes quickly above 90℃, leading to a rapid increase in viscosity and poorer processing, we set the reaction temperature between 80°C and 90℃.   4 Conclusion Our initial tests included scaled-up experiments and pilot production runs, which successfully yielded acceptable products. They were supplied to many leather shoe factories and achieved satisfactory results. The quality met the various standards required for shoemaking. CR-MMA grafted adhesive shows better peel strength on PVC artificial leather compared to regular CR adhesive used for boots.The addition of a small quantity of isocyanate (5-10%) can serve as a temporary curing agent. The -NCO group in the isocyanate then reacts with active hydrogen in the rubber, creating an amide bond. This reaction strengthens the rubber's internal structure, improving the overall bond strength.   Website: www.elephchem.com Whatsapp: (+)86 13851435272 E-mail: admin@elephchem.com

Chloroprene rubber (CR) is a synthetic rubber obtained by polymerization of chloroprene. It is widely used because of its excellent aging resistance, oil resistance, corrosion resistance and other properties. Polychloroprene Rubber CR2442 vulcanized rubber has good physical properties and can be used in many occasions (Such as chloroprene rubber adhesive). However, since the process of CR2442 in internal mixing, open mixing and vulcanization is not easy to master, the physical properties of the prepared vulcanized rubber are sometimes poor, which affects its production and application.   1. The influence of process parameters on the preparation of mixed rubber and vulcanized rubber 1.1 Internal mixer mixing process CR2442 has high requirements for the mixing process. When preparing CR2442 mixed rubber, the initial temperature, mixing time and rotor speed of the internal mixer have a great influence on the discharge temperature. The discharge temperature is an important parameter for measuring the mixing process. The optimal discharge temperature of CR2442 is 110℃. The order of adding various materials during the mixing process is also important. The correct way to add materials to CR2442 during the mixing process is: add CR2442 and small materials at the same time → add carbon black → add white carbon black and operating oil in sequence.   1.2 Mixing process of open mill After the mixed rubber prepared by the internal mixer is cooled, the vulcanization system is added on the open mill. The vulcanization system includes vulcanizing agent and accelerator. The correct way to add is to add accelerator first and then vulcanizing agent. When adding the vulcanization system to the mixed rubber on the open mill, it is generally required that there is accumulated rubber on the roller. With the shearing and extrusion of the open mill, the roller temperature will increase significantly. When the temperature of the rubber is too high, the rubber should be cut, pulled out and cooled, and then the rubber should be mixed after it is completely cooled.   1.3 Vulcanization process After adding the vulcanization system on the open mill, the rubber is cooled and placed for 16~24h before vulcanization. Since the CR2442 mixed rubber is easy to crystallize at low temperatures, it is generally necessary to perform indirect heating treatment in an oven. The vulcanization time of CR2442 was set to 30, 40, 50, 60, 70 and 80 minutes respectively. After many tests, it was found that the tensile strength and elongation at break of the vulcanized rubber were the largest when the vulcanization time was 60 minutes. Therefore, the optimal vulcanization time of CR2442 was determined to be 60 minutes.   1.4 Bonding operation In the process of bonding the mixed rubber and brass, the rubber is first cut into sheets with the same length and width as the mold. After the mold is preheated, the cut film is placed in the mold cavity. Since the mold is heated, placing it too slowly will cause early vulcanization of the rubber, reduce the fluidity of the rubber, make the bonding insufficient, and then reduce the bonding force. Therefore, the scorch time should be controlled to be much longer than the placement time of the film.   2. Influence of vulcanization system, reinforcement system and bonding system Vulcanization system: When CR2442 uses only zinc oxide and magnesium oxide for vulcanization, the resulting rubber's physical properties are worse compared to when zinc oxide, magnesium oxide, sulfur, and accelerator DM are used as a system. Reinforcement system: The reinforcement system of CR2442 is often based on carbon black and supplemented by white carbon black. Bonding system: Rubber as a single material can no longer meet the needs of society, and it is often necessary to bond rubber to metal to expand its scope of use. CR2442 is usually bonded to metal using a resorcinol-methylene-white carbon black-cobalt salt bonding system.   3. Conclusion When mixing, it's important to think about temperature, how long you mix, and how fast the rotor spins. Also, when you add the vulcanization system using the open mill, pay attention to the order you add things. The heat from the rollers can really change things.For vulcanization and bonding, if you make sure the scorch time is longer than it takes to place the sample, you can get better quality vulcanized rubber and better bonding with other types of materials. The CR2442 discharge temperature matters too. It's a good idea to add white carbon black as a reinforcement in CR2442. This helps control how fast vulcanization and bonding happen.   Website: www.elephchem.com Whatsapp: (+)86 13851435272 E-mail: admin@elephchem.com

Chloroprene adhesive is popular in the shoemaking industry because it bonds materials very well. Among them, grafted chloroprene adhesive is the most widely used. As shoe materials develop towards lighter colors, the color requirements for adhesives are becoming more and more stringent. Right now, SN24 adhesive starts out light, but it yellows pretty fast after sitting around for a while, especially if it's in the sun. After being prepared into chloroprene adhesive, there is a yellowing problem, which leads to two problems: first, it affects the appearance of shoes. For light-colored shoes such as sports shoes and travel shoes, the problem is more prominent; second, the darkening of color is a manifestation of polymer aging, which leads to the deterioration of the bonding performance of the adhesive. Therefore, in order to improve the appearance of footwear and ensure that it does not turn yellow during wearing, a yellowing-resistant adhesive should be used.   1. Experimental materials Chloroprene rubber latex: Chloroprene Rubber SN-242, Sana Synthetic Rubber Co., Ltd.; toluene, methyl methacrylate, butanone, BPO, SKYPRENE G-40S; Denka A90 Chloroprene rubber   2. Performance test results 2.1 Comparison of glue solutions The different types of dry glue obtained by the drum were dissolved in toluene to obtain the glue solution comparison chart in Figure 1, and the comparison chart of different types of glue solutions after heating is shown in Figure 2.   As can be seen from Figure 1, the color of the glue solution in this experiment is not much different from the color of the same type of glue solution at home and abroad. After adding BPO and MMA and shaking well, the color will change.After being tested, SN242A became yellow. Domestic rubber samples No. 2 and No. 3 also turned yellow. The other samples got a bit darker, but our test rubber was still lighter than domestic rubber No. 4. Its color was close to that of samples No. 7 and No. 8.After 20 minutes in a 90℃ oven, rubber samples No. 1, 2, 3, and 5 turned yellow. Samples No. 4, 6, 7, and 8 got lighter. After an hour, the colors changed in the same way, but everything was darker than it was at 20 minutes.As you can see in Figures 1 and 2, when this test rubber was dissolved in toluene and heated with an initiator, it looked a little whiter than similar domestic glues. It looked about the same as similar foreign glues.   2.2 Grafting comparison According to the grafting formula, 0.1 parts of BPO and 50 parts of methyl methacrylate were added, and different types of chloroprene rubber were grafted. The viscosity of the solution before and after grafting was measured, as shown in Table 4. The comparison between the experimental glue and the domestic glue after grafting is shown in Figure 3.     Figure 3 presents a comparison between our experimental glue and a domestic glue following grafting.When exposed to free radicals, the unsaturated double bonds on the chloroprene rubber backbone transform the MMA monomer into a monomer free radical. This then grafts and copolymerizes with CR through a chain transfer reaction, creating a complex graft copolymer. This process leads to asymmetry and polarity in the adhesive structure, improving adhesion.   Based on the data in Table 5, our experimental glue shows a high grafting rate, nearly 100%. This solves the issue of low grafting rates seen with SN242, which stem from residual terminators. Plus, it eliminates the problem of red glue forming during the grafting process. Figure 3 is a comparison chart of the grafted glue solution after being placed in the sun for several days. The color of the experimental glue solution is much lighter than that of SN242.   2.3 GPC comparison According to Figure 4 and Table 5, the relative molecular weight and relative molecular weight distribution of the experimental glue are not much different from those of foreign glue. The average relative molecular weight is around 350,000, and the relative molecular weight distribution is below 2.3, which is larger than the relative molecular weight of domestic grafted glue, and the relative molecular weight distribution is narrow, and the regularity of the molecular chain is higher.     2.4 DSC comparison Based on the data in Figure 5 and Table 5, the experimental glue's glass transition temperature is similar to both domestic and foreign glues. The experimental glue's crystallization temperature, which is higher than the domestic glue, is nearly the same as the foreign glue.       3 Conclusion The chloroprene rubber adhesive developed in this paper has excellent yellowing resistance and stable grafting performance. Through DSC and GPC analysis, grafted chloroprene rubber with uniform relative molecular weight and high regularity was obtained, and its performance is comparable to that of the same type of foreign rubber.   Website: www.elephchem.com Whatsapp: (+)86 13851435272 E-mail: admin@elephchem.com

Chloroprene rubber (CR) is an important variety of synthetic rubber. It stands up well to light, aging, flexing, acids, bases, ozone, flames, heat, and oil. It also has good physical and electrical properties. Its comprehensive performance is unmatched by natural rubber and other synthetic rubbers. It is widely used in defense, transportation, construction, light industry and military industry. Chloroprene rubber has several uses. It's a key element in making auto parts, machinery, industrial items, and adhesives. You'll also find it in construction materials, coated fabrics, and wire and cable insulation. By itself, chloroprene rubber is used to create rubber harness clips and shock absorbers for cars and farm equipment. Initially, chloroprene rubber from Japan's DENKA and Japan's Toyo Soda was used. Later, due to the increase in raw material prices and the restrictions of the procurement cycle, a series of research and development work on the replacement of imported chloroprene rubber with domestic chloroprene rubber was carried out. Finally, the replacement goal was successfully achieved, and some process and formula problems of domestic chloroprene rubber in the use process were solved.   1. Neoprene rubber model Imported neoprene rubber model: Denka M120 Chloroprene Rubber, a product of Japan DENKA, light-colored blocks; B-10, a product of Japan Toyo Soda, light-colored blocks. Domestic neoprene rubber model: CR3221, a product of Chongqing Changshou Chemical Co., Ltd. Polychloroprene Rubber CR3221 is a chloroprene polymer with sulfur and diisopropyl xanthate disulfide as mixed regulators, with a low crystallization rate, a relative density of 1.23, beige or brown blocks, and a non-polluting type.   2. Production process performance comparison Imported neoprene handles better during production. For example, the raw rubber pieces do not stick together, even after baking, which makes them easy to measure. The process is smooth; it does not stick to the roller, so removing it is simple. The semi-finished film is stiff and holds its shape well. Domestic neoprene does not perform as well. The rubber pieces tend to stick, especially after baking. The rubber also sticks to the roller, which makes removal hard, and the semi-finished film sticks easily and loses its shape. Despite these things, domestic neoprene has some benefits. It mixes powder faster and with less effort in both internal and open mixers. Rubber from Japan is harder to mix. In the open mixer, M-120 can even fall off the roller at first. The internal mixer requires more effort and time, especially in the winter. Domestic mixed rubber still works well after being stored for a long time. Rubber from Japan, especially M-120, gets hard and loses its flexibility after two to four weeks. Tests show that production methods that work for imported neoprene do not work well for domestic neoprene. The original method needs some changes. If not, it will be hard to make it work for production, even when the physical and mechanical qualities meet the standards.   3.  Conclusion Compared with Japanese chloroprene rubber, domestic chloroprene rubber CR3221 has lower Mooney viscosity and greater viscosity, which is more favorable for mixing and powder consumption, and can significantly reduce the operation time, but the processability is poor and the operation is difficult. If the temperature is not well controlled, the operation is improper or the rubber is over-mixed, it may cause the roller to stick or even fail to unload normally. By selecting the correct process conditions and methods and adjusting the formula appropriately, it can fully meet the production needs.   Website: www.elephchem.com Whatsapp: (+)86 13851435272 E-mail: admin@elephchem.com

Chloroprene rubber (CR), a synthetic material, is a common choice for making timing belts because of its good physical and chemical traits. Neoprene timing belts resist aging well and work best in regular transmission systems, but some situations might need different materials. 1. Aging resistance of chloroprene rubber timing belts Neoprene resists oxidation well, helping timing belts stay flexible and strong during regular use. This prevents the material from getting fragile or breaking down due to oxidation, making it good for machines exposed to air for extended periods, as it reduces the possibility of cracks or surface hardening. Heat resistance: The operating temperature range is generally between -20°C and 100°C, and it can operate for a long time in a medium-high temperature environment; under high temperature conditions, although its performance will decrease slightly, the aging process can be delayed by adding heat-resistant agents. Anti-ultraviolet performance: Neoprene has moderate anti-ultraviolet ability, but the surface may oxidize under long-term exposure to strong light, resulting in color changes and the formation of tiny cracks. Moisture resistance: Neoprene has good resistance to moisture and is suitable for high humidity environments. It is not easy to deteriorate due to moisture intrusion. Chemical corrosion resistance(Chloroprene Rubber SN-236T): It has good corrosion resistance to grease, weak acid, alkali and some chemical solvents, which slows down the aging rate, but is not suitable for contact with strong oxidizing chemicals.   2. Applicable scenarios of chloroprene rubber timing belts Industrial transmission equipment(Chloroprene Rubber SN-244X): Applicable to power transmission of conventional mechanical equipment, such as textile machinery, packaging equipment and general processing equipment. Medium temperature environment: It performs well in medium and high temperature (below 100°C) application scenarios, such as industrial drying equipment or HVAC systems. Indoor environment: Equipment with low requirements for UV resistance, such as indoor automation equipment or low maintenance systems. Medium humidity and chemical environment: It can be applied to equipment that contacts oils and weak acid and alkali environments, such as food processing machinery and light chemical equipment.   3. Limitations of aging resistance of chloroprene rubber timing belt Prolonged exposure to temperatures above 100°C can speed up the aging process, leading to reduced flexibility or hardening of the timing belt. When working in such conditions, fluororubber or silicone rubber belts are the preferred choice. Extended exposure to strong sunlight can cause surface oxidation and cracking, which reduces the lifespan of the belt. Polyurethane belts or those with anti-UV coatings are advisable for outdoor setups. Strong acids, bases, or concentrated chemical solvents can cause corrosion if the material isn't resistant enough.   4. Methods to extend the aging resistance of chloroprene rubber timing belts Reasonable storage: Store in a dry, ventilated, light-proof environment to avoid ultraviolet radiation and high temperature. Regular inspection: Regularly check whether there are cracks or hardening on the surface of the timing belt during use, and remove oil and chemical residues in time. Adding antioxidants: By adding antioxidants or anti-ultraviolet ingredients during the manufacturing process, the aging resistance of the timing belt can be significantly improved. Optimize working conditions: Avoid running the synchronous belt under excessive tension or extreme temperature to reduce the risk of aging.   Chloroprene rubber synchronous belts resist oxidation, heat, and moisture well, so they age slowly and work for many standard jobs. Still, they might not work as well when it's very hot, there's a lot of ultraviolet light, or things are very corrosive. You can make these belts last longer by storing and using them properly and keeping up with regular maintenance. Because of this, they're a solid, affordable choice.   Website: www.elephchem.com Whatsapp: (+)86 13851435272 E-mail: admin@elephchem.com  

What is Neoprene? Neoprene, also known as polychloroprene, is a synthetic rubber made by the free radical polymerization of chloroprene and is used in a wide variety of applications. It was first introduced by DuPont and was used by the U.S. military during World War II the following decade. Although it is one of the earliest synthetic rubbers, it is still very popular today. Neoprene has a wide range of applications due to its strong physical properties, chemical resistance, and flame retardancy. Neoprene is typically molded by injection molding, transfer molding, or compression molding.     Properties of Neoprene Neoprene has many excellent properties that make it a widely used synthetic rubber. As with any polymer, there are some disadvantages to consider when considering using Neoprene for your application. Click here to learn more about how to choose the right type of rubber to manufacture your product.   Common Applications of Neoprene Neoprene is a very commonly used rubber polymer that has a wide range of uses. It is resistant to water, fire, ozone, sunlight, and many other chemicals, making it a very versatile material. These applications include refrigeration seals, Freon/air conditioning, engine mounts, engine coolant, oil and chemical tank linings, automotive gaskets and seals, and weather stripping.   Other examples of neoprene applications include: Water Sports(Chloroprene Rubber SN-242A). Neoprene is commonly used in wetsuits due to its waterproof and insulating properties. It is also used in a variety of equipment for scuba diving, fishing, surfing, boating, and other water sports. Everyday Use(Chloroprene Rubber SN-241). Neoprene is used in many household items we use every day, including mouse pads, smartphone cases, laptop bags, remote controls, dishwashing gloves, and even musical instruments. Face Masks(Chloroprene Rubber SN-243). During the COVID-19 pandemic, neoprene was found to be an effective material for making face masks. Since then, many manufacturers have used it to produce protective masks.   Website: www.elephchem.com Whatsapp: (+)86 13851435272 E-mail: admin@elephchem.com