Neoprene AD-20

In the research and development and production of high-performance industrial adhesives, chloroprene rubber has consistently held a core position due to its excellent adhesion, aging resistance, and flame retardancy. However, with the increasing demand for synthetic materials (such as PVC, PU, and EVA) in modern industry, traditional adhesives face challenges such as poor wettability and mismatched polarity. Among the many types of chloroprene rubber, Polychloroprene Rubber CR244 and Adhesive Type CR248 Chloroprene Rubber are two of the most representative products. Although they share many similarities in their basic physical properties, the differences in the critical dimension of "grafting performance" determine their ultimate performance in different industrial scenarios.   1. CR244: The Cornerstone of Rapid Crystallization and High Cohesive Strength CR244 type chloroprene rubber is polymerized using diisopropyl xanthate disulfide or dodecyl mercaptan as a regulator, possessing extremely significant physical characteristics.     ♣ Physical Characteristics and Performance Advantages CR244's most prominent technical feature is its rapid crystallization. This characteristic allows the adhesive to quickly establish initial strength after application, greatly shortening the waiting time for industrial assembly. Its regular molecular structure gives the adhesive layer extremely high cohesive strength. At room temperature, the adhesive strength exhibited by CR244 is sufficient to meet the needs of most porous materials. Its appearance is off-white or beige flakes, with a stable density of around 1.23. In terms of technical indicators, CR244 offers a very finely divided viscosity range. From the ultra-low viscosity CR2440 (13-24 mPa.s, 5% toluene solution) to the high-viscosity CR244B (above 140 mPa.s), this wide viscosity coverage allows adhesive manufacturers to precisely adjust the formulation solid content according to the needs of brushing, spraying, or scraping processes. ♣ Applications in Traditional Fields Due to its peel strength typically maintained above 90 N/cm, CR244 is widely used in the self-adhesion and mutual adhesion of traditional materials such as rubber, leather, fibers, wood, and cement products. It is comparable in performance to top-tier international models, such as Denka's A series (such as Denka Chloroprene A-100) and DuPont's AD series (such as Neoprene AD-20), and is the preferred base material for producing high-quality general-purpose neoprene adhesives.   2. CR248: A Breakthrough in Polarity Achieved Through Graft Modification If CR244 represents a general-purpose base material, then CR248 is an advanced version designed to address the challenges of bonding "difficult-to-bond materials." The fundamental difference between it and CR244 lies in the plasticity and grafting properties of its molecular chain.     ♣ Core Technology: Grafting and Copolymerization While CR248 retains the basic performance advantages of CR244, it has active sites reserved during the molecular design stage. This allows CR248 to undergo monomer grafting copolymerization with active monomers such as methyl methacrylate (MMA) and acrylic acid (BA) through chemical means. The significance of this graft modification is that by introducing polar monomer side chains onto the non-polar main chain of neoprene rubber, the surface energy and polarity of the adhesive are significantly improved. This not only improves the wettability of the adhesive on polar substrates but also enhances the bonding force at the interface through chemical bonding. ♣ Professional Performance for Synthetic Materials In modern footwear, automotive interiors, and luggage industries, synthetic materials such as PVC (polyvinyl chloride), PU (polyurethane), and EVA (ethylene-vinyl acetate copolymer) are widely used. Due to the high surface polarity or the presence of plasticizers in these materials, traditional CR244 adhesives often experience delamination. CR248 is optimized precisely for this purpose. The modified CR248 adhesive can establish a stable bridging relationship with these synthetic materials. Although its nominal peel strength (approximately 70 N/cm) is slightly lower than that of CR244, its actual bonding stability and plasticizer resistance on specific polar materials far exceed the latter.   3. In-depth Comparison of Technical Parameters of CR244 and CR248 Differences in viscosity control: CR244 tends to exhibit its viscosity gradient at lower concentrations (5% toluene solution), which is more conducive to producing highly permeable primers. CR248's technical specifications are typically based on a 15% toluene solution, and it is divided into Type I (1000-3000 mPa.s) and Type II (3001-6000 mPa.s). This means that under the same viscosity requirements, CR248 can support formulations with higher solid content, thereby reducing the environmental impact of solvent evaporation and increasing the dry film thickness per application.   Volatile content and purity: Both products exhibit excellent purity control, with volatile content strictly controlled to below 1.5% (CR248 is further optimized to 1.2%). This ensures that the adhesive does not produce excessive bubbles during the drying process, guaranteeing the density and aging resistance of the adhesive layer.   Storage stability: Both products perform similarly in terms of storage requirements. They can be stored for one year at temperatures below 20°C, while in summer environments at 30°C, it is recommended to use them within six months. For manufacturers, strict temperature control is crucial to maintaining the activity of chloroprene rubber and preventing premature self-polymerization.   4. How to choose the right product based on your needs? If the substrate is natural rubber, genuine leather, or wood products: CR244 is the preferred choice. It provides faster initial tack and higher ultimate cohesive strength, and the formulation cost is relatively more advantageous. For products requiring precise rheological control, its wide range of viscosity grades can be used for blending. If modern synthetic materials such as PVC, PU, ​​and EVA are involved: CR248 is the ideal choice. Especially when your adhesive needs to be modified with MMA to produce "universal grafting adhesive," the grafting active sites provided by CR248 ensure the efficient progress of the chemical reaction, resulting in finished adhesives with excellent migration resistance and cross-material bonding capabilities. Considering environmental protection and cost: CR248's high solid content characteristics help develop low-VOC adhesives that meet environmental standards. Although the unit price of the raw material may be slightly higher than CR244, its low rework rate and high-performance characteristics on difficult-to-bond materials often result in lower overall industrial costs.   Website: www.elephchem.com Whatsapp: (+)86 13851435272 E-mail: admin@elephchem.com

For outdoor environments, you should choose EPDM. Nitrile suits oil and fuel contact best. For mixed chemical resistance, select neoprene and chloroprene. Evaluate your project’s environmental exposure, chemical compatibility, and temperature requirements. These factors will help you make the right material choice for reliable, long-term performance.   1. Comparison Overview   Key Properties When you compare Chloroprene Rubber(such as Polychloroprene Rubber CR2440) , EPDM, and Nitrile Rubber, you need to focus on several critical properties. These include oil resistance, weathering, ozone/UV resistance, fire performance, temperature range, and cost. The table below summarizes how each material performs in these areas: Property Property Chloroprene Rubber EPDM Nitrile Rubber Oil Resistance Moderate Poor Excellent Weather Resistance Excellent Excellent Fair-Good Ozone/UV Resistance Poor Fair-Good Good Temperature Range (°F) -40 to 225 -60 to 300 -40 to 250 Cost Moderate Low-Moderate Moderate   Ozone and Weathering Resistance Table Rubber Type Ozone Resistance Weather Resistance Chloroprene Rubber Poor Excellent EPDM Fair-Good Excellent Nitrile Rubber Good Fair-Good   Fire Resistance Classification Table Material Fire Resistance Classification Chloroprene Rubber Not a fire retardant, but less flammable than other commercial rubbers; melts when aflame but can be extinguished. EPDM Good level of flame resistance; requires compounding with blockers to meet fire standards. Nitrile Rubber Not rated   2. Pros and Cons You should weigh the advantages and disadvantages of each material before making your selection. Chloroprene Rubber Pros: Offers balanced resistance to oil, chemicals, and weathering; Performs well in outdoor and marine environments; Less flammable than many other rubbers. Cons: Faces supply chain risks due to regulatory restrictions; Ozone resistance is lower than EPDM or Nitrile; Cost can be higher than EPDM. EPDM Pros: Excels in outdoor, UV, and ozone-exposed applications; Maintains flexibility at low temperatures; New formulations provide flame resistance and self-healing properties; Cost-effective for large-scale projects. Cons: Poor resistance to oils and fuel; Requires additives for optimal fire performance; Not suitable for applications involving petroleum-based fluids. Nitrile Rubber Pros: Outstanding oil and fuel resistance; Enhanced heat resistance in modern compounds; Can be blended for specialized performance, such as static dissipation; Eco-friendly options are emerging. Cons: Weathering and ozone resistance are lower than EPDM; Not inherently flame retardant; Flexibility decreases at low temperatures.   3. Choosing the Right Material Environmental Factors You need to assess the environment where your rubber material will operate. Outdoor exposure, sunlight, ozone, and weathering can quickly degrade some rubbers. EPDM stands out for its excellent resistance to ozone and sunlight, making it the top choice for outdoor applications. You benefit from EPDM’s ability to withstand harsh weather, UV rays, and temperature swings. This material can last up to 20 years or more in outdoor conditions. If your project involves exposure to oils or solvents, Chloroprene Rubber (such as Neoprene AD-20) offers good oil resistance and performs well in parts exposed to chemicals. EPDM is also more environmentally friendly because it is non-toxic and recyclable, while Neoprene (Chloroprene Rubber) is less sustainable.   Chemical Resistance You must match the rubber’s chemical resistance profile to your application. Each material reacts differently to oils, fuels, and industrial chemicals. Nitrile Rubber provides high oil resistance but performs poorly against weather and ozone. Chloroprene Rubber offers moderate oil resistance and excellent weather resistance. EPDM does not resist oils but excels in weather and ozone resistance. Rubber Type Oil Resistance Weather Resistance Flame Resistance Ozone Resistance Nitrile Rubber High Poor Poor Poor Chloroprene Rubber Moderate Excellent Very Good Excellent EPDM N/A Excellent N/A Excellent You should always check the chemicals your project will encounter. Select Nitrile Rubber for oil and fuel contact. Use Chloroprene Rubber for balanced resistance to chemicals and weather. Choose EPDM for applications with no oil exposure but high weathering demands.   4. Summary Choosing the right rubber material for your project depends on matching its properties to your application’s demands. You need to consider oil resistance, weathering, ozone and UV exposure, and the specific environment where the rubber will perform. Each rubber type offers unique strengths that make it ideal for certain uses.   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