A weather-resistant chlorinated polyethylene rubber composition and a method for producing the same

Abstract

The application discloses a weather-resistant chlorinated polyethylene rubber composition and a preparation method thereof, and belongs to the technical field of chlorinated polyethylene rubber compositions. The preparation method of the weather-resistant chlorinated polyethylene rubber composition comprises the following steps: preparing hybrid modified chlorinated polyethylene rubber, premixing, mixing and vulcanizing. The hybrid modified chlorinated polyethylene rubber is prepared by mixing distilled water, sodium dodecyl benzene sulfonate and chlorinated polyethylene rubber powder, stirring at normal temperature, continuously stirring, dropwise adding methyl orthosilicate, dropwise adding an aqueous solution of magnesium chloride hexahydrate after the dropwise adding of the methyl orthosilicate is completed, adjusting the pH value to 12.8-13.2 after the dropwise adding of the aqueous solution of magnesium chloride hexahydrate is completed, stirring at 68-72 DEG C, filtering, washing the filter residue, and vacuum drying. The chlorinated polyethylene rubber composition prepared by the method has good weather resistance, high tear strength and tensile strength, and good heat air aging resistance.

Description

Technical Field

[0001] This invention relates to the field of chlorinated polyethylene rubber composition technology, and specifically to a weather-resistant chlorinated polyethylene rubber composition and its preparation method. Background Technology

[0002] Chlorinated polyethylene (CPE) is a linear saturated random polymer obtained by reacting polyethylene with chlorine. Its main chain structure is the same as polyethylene, consisting of carbon-carbon single bonds, except that some hydrogen atoms on the carbon atoms of the main chain are replaced by chlorine atoms, and the chlorine atoms are randomly distributed along the polyethylene main chain. Because the main chain of CPE contains almost no unsaturated bonds, it exhibits stable chemical properties. Furthermore, compared to raw polyethylene, CPE, due to the presence of chlorine atoms in its main chain structure, is far superior to polyethylene in terms of flame retardancy, oil resistance, corrosion resistance, and aging resistance. The material properties of CPE vary significantly depending on the chlorine content in its main chain. As the chlorine content increases, the material properties of CPE gradually shift towards those of rubber, and then gradually towards those of a brittle resin. Typically, when the chlorine content (mass fraction) in CPE is 30-40%, CPE exhibits the properties of a rubber material, and is used as CPE rubber.

[0003] Chlorinated polyethylene rubber possesses moderate strength and flexibility, as well as low melt viscosity and plasticizing temperature. As an environmentally friendly specialty rubber, chlorinated polyethylene rubber also exhibits excellent cold resistance, aging resistance, ozone resistance, oil resistance, and flame retardancy. As an elastomer with promising applications, chlorinated polyethylene rubber is mainly used in the production of products such as wires and cables, hoses, conveyor belts, rubber dams, automobile inner tubes, and elevator handrails. Due to its excellent heat resistance, chlorinated polyethylene rubber is currently beginning to replace more expensive chlorosulfonated polyethylene rubber, ethylene-acrylate rubber, and chlorinated ether rubber in the production of automotive engine peripheral hoses.

[0004] However, chlorinated polyethylene rubber has the following shortcomings in use: because it is synthesized from high-density polyethylene with a lower molecular weight or a wider molecular weight distribution, its tensile strength is relatively low; the main chain structure of chlorinated polyethylene rubber contains a large number of chlorine atoms, which will undergo an aging decomposition reaction to generate hydrogen chloride under the action of light and heat, resulting in insufficient weather resistance of products made from chlorinated polyethylene rubber when used in harsh environments.

[0005] To address the aforementioned shortcomings, the following solutions are commonly adopted: using vulcanization systems and reinforcing filler systems that improve tensile strength and weather resistance; adding stabilizers and antioxidants to chlorinated polyethylene rubber; and hybridizing chlorinated polyethylene rubber.

[0006] For the vulcanization systems used in chlorinated polyethylene rubber, thiourea vulcanization systems, thiadiazole vulcanization systems, and peroxide vulcanization systems are commonly used. Among them, the thiourea vulcanization system has a slow vulcanization speed and high toxicity; the thiadiazole vulcanization system has a faster vulcanization speed, a higher degree of vulcanization, and excellent overall mechanical properties, and can use aromatic oils. However, the vulcanization auxiliaries used in the thiadiazole vulcanization system are expensive, and due to limitations in domestic production capacity, demand mainly relies on imports; the peroxide vulcanization system has a very fast vulcanization rate, and the vulcanized rubber prepared has outstanding heat resistance and low compression set, making it the commonly used vulcanization system for chlorinated polyethylene rubber in my country.

[0007] For reinforcing filler systems used in chlorinated polyethylene rubber, carbon black and silica are commonly used. As the amount of these fillers increases, the tensile strength will increase accordingly.

[0008] For stabilizers and antioxidants used in chlorinated polyethylene rubber, commonly used stabilizers and antioxidants include magnesium oxide, lead oxide, metal salts, metal soaps, epoxy resins and ester antioxidants, such as antioxidants DLTP and DSTP, as well as antioxidants RD and NBC commonly used in the rubber industry.

[0009] When performing hybrid modification on chlorinated polyethylene rubber, a common method is to generate silica in situ in the rubber powder. Specifically, this is done through the sol-gel method, using silica precursors as raw materials to introduce a siloxane network structure on the surface of the rubber powder, and to achieve interpenetration between the siloxane network structure and the internal network of the rubber powder particles, thereby improving the tensile strength and weather resistance of chlorinated polyethylene rubber.

[0010] However, after combining the above solutions—namely, generating silica in situ on the surface of rubber powder using the sol-gel method, mixing it with carbon black, stabilizers, and antioxidants, adding plasticizers, and then using a peroxide vulcanization system to vulcanize—to prepare a chlorinated polyethylene rubber composition with excellent tensile strength and weather resistance, and conducting performance testing, the applicant found the following shortcomings: The prepared chlorinated polyethylene rubber composition has low tear strength. Analysis revealed that, due to the inherently low tear strength of chlorinated polyethylene rubber, compared to thiourea and thiadiazole vulcanization systems, the peroxide vulcanization system still exhibits low tear strength. Furthermore, the peroxide vulcanization system has limited effect on improving the tensile strength and weather resistance of the prepared chlorinated polyethylene rubber composition. Analysis showed that, due to the interaction between the rubber powder and silica during in-situ silica generation, the amount of silica generated on the surface of the rubber powder is limited, further limiting its effect on improving the tensile strength and weather resistance of the prepared chlorinated polyethylene rubber composition.

[0011] To address the two shortcomings mentioned above, a common solution found through research is the sol-gel method. This method involves introducing vinyl functional groups onto the surface of silica during in-situ silica generation in the rubber powder. These vinyl functional groups increase the amount of silica generated on the rubber powder surface. Then, unsaturated carboxylic acid metal salts are added to the vulcanization system as crosslinking aids. During vulcanization, these unsaturated carboxylic acid metal salts not only undergo self-polymerization but also graft onto the chlorinated polyethylene molecular chains and form chemical bonds with the vinyl groups on the silica surface. This further allows the hybridized rubber powder to participate in the vulcanization structure of chlorinated polyethylene, resulting in a more complete network structure and improved system performance. However, the applicant found that when using this method, directly adding unsaturated carboxylic acid metal salts resulted in relatively large particles that were prone to agglomeration and poor solubility in chlorinated polyethylene rubber, thus limiting the improvement in tensile strength and weather resistance. Although adding unsaturated carboxylic acid metal salts through in-situ generation could avoid this problem, it still promoted the breaking of C-Cl bonds in chlorinated polyethylene rubber compared to direct addition, thereby affecting the heat aging resistance of chlorinated polyethylene rubber. This issue was also addressed in the paper "The Influence of Zn(MAA)2 Addition Method on CM Performance" by Sun Achao and Gao Guangtao in *Special Rubber Products*, published in 2013. Summary of the Invention

[0012] To address the shortcomings of existing technologies, this invention provides a weather-resistant chlorinated polyethylene rubber composition and its preparation method. The chlorinated polyethylene rubber composition prepared by this invention not only has good weather resistance, but also high tear strength and tensile strength, and good resistance to hot air aging.

[0013] To solve the above technical problems, the technical solution adopted by the present invention is as follows: A method for preparing a weather-resistant chlorinated polyethylene rubber composition includes the following steps: preparing a hybrid modified chlorinated polyethylene rubber, premixing, compounding and vulcanizing; The preparation of hybrid modified chlorinated polyethylene rubber involves mixing distilled water, sodium dodecylbenzene sulfonate, and chlorinated polyethylene rubber powder, stirring at 200-500 rpm for 30-60 minutes at room temperature, continuing stirring, adding methyl orthosilicate dropwise, adding an aqueous solution of magnesium chloride hexahydrate dropwise after the addition is complete, adding an aqueous solution of sodium hydroxide to adjust the pH to 12.8-13.2, stirring at 68-72℃, filtering, collecting the filter residue, washing until the filtrate is neutral, and vacuum drying to obtain hybrid modified chlorinated polyethylene rubber. As a preferred embodiment of the above technical solution, the preparation of hybrid modified chlorinated polyethylene rubber further includes some or all of the following technical features: As an improvement to the above technical solution, in the preparation of hybrid modified chlorinated polyethylene rubber, the mass ratio of water, sodium dodecylbenzene sulfonate, chlorinated polyethylene rubber powder, methyl orthosilicate, and magnesium chloride hexahydrate aqueous solution is 20000-22000:4-5:2000:80-90:500-550. As an improvement to the above technical solution, in the preparation of hybrid modified chlorinated polyethylene rubber, the addition time of methyl orthosilicate is 1.5-2 hours. As an improvement to the above technical solution, in the preparation of hybrid modified chlorinated polyethylene rubber, when adding an aqueous solution of magnesium chloride hexahydrate, the addition time of the aqueous solution of magnesium chloride hexahydrate is 1.5-2 hours. As an improvement to the above technical solution, in the preparation of hybrid modified chlorinated polyethylene rubber, the stirring time at 68-72℃ is 2-2.5h. As an improvement to the above technical solution, in the preparation of hybrid modified chlorinated polyethylene rubber, the chlorine content of the chlorinated polyethylene rubber powder is 36% by mass, and the manufacturer is Weifang Shuoyi Chemical Co., Ltd., with the grade CM3650. As an improvement to the above technical solution, in the preparation of hybrid modified chlorinated polyethylene rubber, the median particle size of the chlorinated polyethylene rubber powder is 280-320 μm; As an improvement to the above technical solution, in the preparation of hybrid modified chlorinated polyethylene rubber, the mass fraction of magnesium chloride hexahydrate in the aqueous solution of magnesium chloride hexahydrate is 18-22%. As an improvement to the above technical solution, in the preparation of hybrid modified chlorinated polyethylene rubber, the mass fraction of sodium hydroxide in the aqueous solution of sodium hydroxide is 8%; The premixing process involves mixing distilled water and methacrylic acid, stirring at 200-500 rpm for 1-1.5 hours at room temperature, continuing to stir, adding carbon black, stirring for 1-1.5 hours, and then vacuum drying to obtain the premixed carbon black. As a preferred embodiment of the above technical solution, the premixing further includes some or all of the following technical features: As an improvement to the above technical solution, during the premixing process, the mass ratio of distilled water, methacrylic acid, and carbon black is 3000-3500:180-200:2000; As an improvement to the above technical solution, the carbon black used in the premixing process is carbon black N550. The mixing and vulcanization process involves adding hybrid modified chlorinated polyethylene rubber and lead stearate to an open mill and mixing for 85-95 seconds. Premixed carbon black is then added and mixed for 235-245 seconds. Antioxidant RD, calcium carbonate, magnesium oxide, and plasticizer TOTM are added and mixed for 145-155 seconds. Vulcanizing agent DCP is added and mixed for 115-125 seconds. The mixture is then passed through a thin pass, formed into triangular sheets 5-7 times, and then sheeted. It is stored at room temperature to obtain the mixed rubber. The mixed rubber is then added to a flat vulcanizing machine for vulcanization. After vulcanization, a weather-resistant chlorinated polyethylene rubber composition is obtained. As a preferred embodiment of the above technical solution, the mixing and vulcanization further include some or all of the following technical features: As an improvement to the above technical solution, during the mixing and vulcanization process, the mass ratio of hybrid modified chlorinated polyethylene rubber, premixed carbon black, calcium carbonate, lead stearate, magnesium oxide, plasticizer TOTM, vulcanizing agent DCP, and antioxidant RD is 98-102:54-56:19-21:2.8-3.2:9.8-10.2:29-31:2.8-3.2:1.4-1.6. As an improvement to the above technical solution, during the mixing and vulcanization process, the roll temperature of the open mill during mixing is 78-82℃, and the roll gap is adjusted to 0.9-1mm. As an improvement to the above technical solution, during the mixing and vulcanization process, the roll gap of the open mill during thin-pass rolling is 0.5-0.6 mm; As an improvement to the above technical solution, the storage time at room temperature during the mixing and vulcanization process is 23-25 ​​hours. As an improvement to the above technical solution, during the mixing and vulcanization process, the vulcanization temperature is 165-175℃ and the vulcanization time is 14-16min.

[0014] A weather-resistant chlorinated polyethylene rubber composition prepared by the aforementioned preparation method.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: The chlorinated polyethylene rubber composition prepared by this invention has a tear strength of 18.3-19.0 kN / m, a tensile strength of 14.8-15.2 MPa, and an elongation at break of 459-471%; it also exhibits a tensile strength at 57°C and an ultraviolet light intensity of 50 W / m. 2 The tensile strength change rate after aging for 168 hours under ultraviolet light with a wavelength of 340 nm was -3.25% to -3.14%, and the elongation at break changed from -9.07% to -8.60%. The tensile strength change rate after aging for 168 hours under ultraviolet light with a wavelength of 340 nm was also -3.25% to -3.14%, and the elongation at break was -9.07% to -8.60%. -6The tensile strength change rate after aging for 120 hours at a flow rate of 15 m / s was +25.84% to +27.32%, and the elongation at break was +2.11% to +2.25%. The tensile strength change rate after aging at 100℃ for 48 hours was -9.42% to -8.27%, and the elongation at break was -19.18% to -16.75%. Detailed Implementation

[0016] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention are now described.

[0017] The ambient temperature in Examples 1-2 and Comparative Examples 1-2 was 22±2℃.

[0018] Example 1 Preparation of chlorinated polyethylene rubber composition 1 This embodiment provides a method for preparing a weather-resistant chlorinated polyethylene rubber composition 1, the specific steps of which are as follows: 1. Preparation of hybrid modified chlorinated polyethylene rubber: 20 kg of distilled water, 4 g of sodium dodecylbenzene sulfonate, and 2000 g of chlorinated polyethylene rubber powder were mixed and stirred at 200 rpm for 30 min at room temperature. While stirring, 80 g of methyl orthosilicate was added dropwise at a uniform rate over 1.5 h. After the addition was completed, 500 g of magnesium chloride hexahydrate aqueous solution was added dropwise at a uniform rate over 1.5 h. After the addition was completed, sodium hydroxide aqueous solution was added to adjust the pH value to 13. The mixture was heated to 70 °C and stirred at 70 °C for 2 h. After filtration, the filter residue was collected, washed until the filtrate was neutral, and vacuum dried to obtain hybrid modified chlorinated polyethylene rubber. The chlorinated polyethylene rubber powder has a chlorine content (mass fraction) of 36%, is manufactured by Weifang Shuoyi Chemical Co., Ltd., and has the brand name CM3650. The median particle size of the chlorinated polyethylene rubber powder is 300 μm; The mass fraction of magnesium chloride hexahydrate in the aqueous solution is 20%. The aqueous solution of sodium hydroxide contains 8% sodium hydroxide by mass. 2. Premixing: Mix 3000g of distilled water and 180g of methacrylic acid, stir at 200rpm for 1 hour at room temperature, continue stirring, add 2000g of carbon black, stir for 1 hour, and vacuum dry to obtain premixed carbon black; The grade of the carbon black is carbon black N550; 3. Mixing and Vulcanization: First, weigh out 100 parts by weight of hybrid modified chlorinated polyethylene rubber, 55 parts by weight of premixed carbon black, 20 parts by weight of calcium carbonate, 3 parts by weight of lead stearate, 10 parts by weight of magnesium oxide, 30 parts by weight of plasticizer TOTM, 3 parts by weight of vulcanizing agent DCP, and 1.5 parts by weight of antioxidant RD. Then, adjust the roller temperature of the open mill to 80℃ and the roller gap to 1mm. Add the hybrid modified chlorinated polyethylene rubber and lead stearate to the open mill and mix for 90 seconds. Add the premixed... The carbon black was mixed for 240 seconds, antioxidant RD, calcium carbonate, magnesium oxide and plasticizer TOTM were added and mixed for 150 seconds, vulcanizing agent DCP was added and mixed for 120 seconds, the roller gap was adjusted to 0.5 mm, thin-passed, and after 6 triangular wraps, it was sheeted and stored at room temperature for 24 hours to obtain the compound; then the compound was added to a flat vulcanizing machine for vulcanization at 170℃×15min. After vulcanization, weather-resistant chlorinated polyethylene rubber composition 1 was obtained.

[0019] This embodiment also provides a weather-resistant chlorinated polyethylene rubber composition 1 prepared by the aforementioned preparation method.

[0020] Example 2 Preparation of chlorinated polyethylene rubber composition 2 This embodiment provides a method for preparing a weather-resistant chlorinated polyethylene rubber composition 2, the specific steps of which are as follows: 1. Preparation of hybrid modified chlorinated polyethylene rubber: 22 kg of distilled water, 5 g of sodium dodecylbenzene sulfonate, and 2000 g of chlorinated polyethylene rubber powder were mixed and stirred at 300 rpm for 60 min at room temperature. While stirring, 90 g of methyl orthosilicate was added dropwise at a uniform rate over 2 h. After the addition was completed, 550 g of magnesium chloride hexahydrate aqueous solution was added dropwise at a uniform rate over 2 h. After the addition was completed, sodium hydroxide aqueous solution was added to adjust the pH value to 13. The mixture was heated to 70 °C and stirred at 70 °C for 2.5 h. After filtration, the filter residue was collected, washed until the filtrate was neutral, and vacuum dried to obtain hybrid modified chlorinated polyethylene rubber. The chlorinated polyethylene rubber powder has a chlorine content (mass fraction) of 36%, is manufactured by Weifang Shuoyi Chemical Co., Ltd., and has the brand name CM3650. The median particle size of the chlorinated polyethylene rubber powder is 300 μm; The mass fraction of magnesium chloride hexahydrate in the aqueous solution is 20%. The aqueous solution of sodium hydroxide contains 8% sodium hydroxide by mass. 2. Premixing: Mix 3500g of distilled water and 200g of methacrylic acid, stir at 300rpm for 1.5h at room temperature, continue stirring, add 2000g of carbon black, stir for 1.5h, and vacuum dry to obtain premixed carbon black; The grade of the carbon black is carbon black N550; 3. Mixing and Vulcanization: First, weigh out 100 parts by weight of hybrid modified chlorinated polyethylene rubber, 55 parts by weight of premixed carbon black, 20 parts by weight of calcium carbonate, 3 parts by weight of lead stearate, 10 parts by weight of magnesium oxide, 30 parts by weight of plasticizer TOTM, 3 parts by weight of vulcanizing agent DCP, and 1.5 parts by weight of antioxidant RD. Then, adjust the roller temperature of the open mill to 80℃ and the roller gap to 1mm. Add the hybrid modified chlorinated polyethylene rubber and lead stearate to the open mill and mix for 90 seconds. Add the premixed... The carbon black was then mixed for 240 seconds. Antioxidant RD, calcium carbonate, magnesium oxide, and plasticizer TOTM were added and mixed for 150 seconds. Vulcanizing agent DCP was added and mixed for 120 seconds. The roller gap was adjusted to 0.5 mm, and the mixture was thin-passed. After six triangular wraps, the mixture was sheeted and stored at room temperature for 24 hours to obtain the compound. The compound was then added to a flat vulcanizing machine for vulcanization at 170℃ for 15 minutes. After vulcanization, weather-resistant chlorinated polyethylene rubber composition 2 was obtained.

[0021] This embodiment also provides a weather-resistant chlorinated polyethylene rubber composition 2 prepared by the aforementioned preparation method.

[0022] Comparative Example 1: Preparation of Chlorinated Polyethylene Rubber Composition 3 This comparative example provides a method for preparing a weather-resistant chlorinated polyethylene rubber composition 3, which adopts a preparation method that is basically the same as that in Example 1, except that: in the first step of preparing the hybrid modified chlorinated polyethylene rubber, the addition of an aqueous solution of magnesium chloride hexahydrate is omitted, and magnesium hydroxide is added in the third step of mixing and vulcanization. The specific steps are as follows: 1. Preparation of hybrid modified chlorinated polyethylene rubber: 20 kg of distilled water, 4 g of sodium dodecylbenzene sulfonate, and 2000 g of chlorinated polyethylene rubber powder were mixed and stirred at 200 rpm for 30 min at room temperature. While stirring, 80 g of methyl orthosilicate was added dropwise at a uniform rate over 1.5 h. After the addition was completed, an aqueous solution of sodium hydroxide was added to adjust the pH to 13. The mixture was heated to 70 °C and stirred at 70 °C for 2 h. After filtration, the filter residue was collected, washed until the filtrate was neutral, and then vacuum dried to obtain hybrid modified chlorinated polyethylene rubber. The chlorinated polyethylene rubber powder has a chlorine content (mass fraction) of 36%, is manufactured by Weifang Shuoyi Chemical Co., Ltd., and has the brand name CM3650. The median particle size of the chlorinated polyethylene rubber powder is 300 μm; The aqueous solution of sodium hydroxide contains 8% sodium hydroxide by mass. 2. Premixing: Mix 3000g of distilled water and 180g of methacrylic acid, stir at 200rpm for 1 hour at room temperature, continue stirring, add 2000g of carbon black, stir for 1 hour, and vacuum dry to obtain premixed carbon black; The grade of the carbon black is carbon black N550; 3. Mixing and Vulcanization: First, weigh out 100 parts by weight of hybrid modified chlorinated polyethylene rubber, 55 parts by weight of premixed carbon black, 20 parts by weight of calcium carbonate, 3 parts by weight of lead stearate, 1.4 parts by weight of magnesium hydroxide, 10 parts by weight of magnesium oxide, 30 parts by weight of plasticizer TOTM, 3 parts by weight of vulcanizing agent DCP, and 1.5 parts by weight of antioxidant RD. Then, adjust the roller temperature of the open mill to 80℃ and the roller gap to 1mm. Add the hybrid modified chlorinated polyethylene rubber, magnesium hydroxide, and lead stearate to the open mill and mix for 90 minutes. Add premixed carbon black and mix for 240 seconds. Add antioxidant RD, calcium carbonate, magnesium oxide, and plasticizer TOTM and mix for 150 seconds. Add vulcanizing agent DCP and mix for 120 seconds. Adjust the roller gap to 0.5 mm and perform thin-pass processing. After 6 triangular wraps, sheet the rubber and store it at room temperature for 24 hours to obtain the compound. Then, add the compound to a flat vulcanizing machine for vulcanization. The vulcanization conditions are 170℃ × 15 min. After vulcanization, weather-resistant chlorinated polyethylene rubber composition 3 is obtained.

[0023] This comparative example also provides a weather-resistant chlorinated polyethylene rubber composition 3 prepared by the aforementioned preparation method.

[0024] Comparative Example 2: Preparation of Chlorinated Polyethylene Rubber Composition 4 This comparative example provides a method for preparing a weather-resistant chlorinated polyethylene rubber composition 4, which adopts a preparation method that is basically the same as that in Example 1, except that the second step of premixing is omitted, and the premixed carbon black is replaced with methacrylic acid and carbon black added separately in the third step of mixing and vulcanization. The specific steps are as follows: 1. Preparation of hybrid modified chlorinated polyethylene rubber: 20 kg of distilled water, 4 g of sodium dodecylbenzene sulfonate, and 2000 g of chlorinated polyethylene rubber powder were mixed and stirred at 200 rpm for 30 min at room temperature. While stirring, 80 g of methyl orthosilicate was added dropwise at a uniform rate over 1.5 h. After the addition was completed, 500 g of magnesium chloride hexahydrate aqueous solution was added dropwise at a uniform rate over 1.5 h. After the addition was completed, sodium hydroxide aqueous solution was added to adjust the pH value to 13. The mixture was heated to 70 °C and stirred at 70 °C for 2 h. After filtration, the filter residue was collected, washed until the filtrate was neutral, and vacuum dried to obtain hybrid modified chlorinated polyethylene rubber. The chlorinated polyethylene rubber powder has a chlorine content (mass fraction) of 36%, is manufactured by Weifang Shuoyi Chemical Co., Ltd., and has the brand name CM3650. The median particle size of the chlorinated polyethylene rubber powder is 300 μm; The mass fraction of magnesium chloride hexahydrate in the aqueous solution is 20%. The aqueous solution of sodium hydroxide contains 8% sodium hydroxide by mass. 2. Mixing and Vulcanization: First, weigh out 100 parts by weight of hybrid modified chlorinated polyethylene rubber, 50.5 parts by weight of carbon black, 4.5 parts by weight of methacrylic acid, 20 parts by weight of calcium carbonate, 3 parts by weight of lead stearate, 10 parts by weight of magnesium oxide, 30 parts by weight of plasticizer TOTM, 3 parts by weight of vulcanizing agent DCP, and 1.5 parts by weight of antioxidant RD. Then, adjust the roller temperature of the open mill to 80℃ and the roller gap to 1mm. Add the hybrid modified chlorinated polyethylene rubber and lead stearate to the open mill, mix for 90 seconds, and then add... Methacrylic acid was mixed for 240 seconds, antioxidant RD, carbon black, calcium carbonate, magnesium oxide, and plasticizer TOTM were added and mixed for 150 seconds. Vulcanizing agent DCP was added and mixed for 120 seconds. The roller gap was adjusted to 0.5 mm, and the mixture was thin-passed. After 6 triangular wraps, the mixture was sheeted and stored at room temperature for 24 hours to obtain the compound. The compound was then added to a flat vulcanizing machine for vulcanization at 170℃ for 15 minutes. After vulcanization, weather-resistant chlorinated polyethylene rubber composition 4 was obtained. The carbon black grade is carbon black N550.

[0025] This comparative example also provides a weather-resistant chlorinated polyethylene rubber composition 4 prepared by the aforementioned preparation method.

[0026] Test case The tear strength, tensile strength, elongation at break, weather resistance, and heat aging resistance of the weather-resistant chlorinated polyethylene rubber compositions 1-4 prepared in Examples 1, 2, Comparative Examples 1, and 2 were tested using the following methods: 1. Tear strength: Tested in accordance with GB / T 529-2008 standard, using right-angled specimens and a tensile rate of 500 mm / min; 2. Tensile strength: Tested in accordance with GB / T 528-2009 standard, using dumbbell-shaped specimens and a tensile rate of 500 mm / min. 3. Elongation at break: Tested in accordance with GB / T 528-2009 standard, using dumbbell-shaped specimens and a tensile rate of 500 mm / min. 4. Weather resistance: UV aging resistance: at a temperature of 57℃ and a UV intensity of 50W / m 2 The change rate of tensile strength and the change rate of elongation at break after aging for 168 hours under ultraviolet light with a wavelength of 340nm. Ozone aging resistance: at a temperature of 40℃ and an ozone volume fraction of 50×10⁻⁶ -6 The change rate of tensile strength and the change rate of elongation at break after aging for 120 hours in an environment with a flow rate of 15 m / s. 5. Heat resistance to air aging: Tested according to GB / T 3512-2014 standard, the aging conditions are the change rate of tensile strength and the change rate of elongation at break at 100℃×48h.

[0027] The test results are as follows:

[0028] The results above show that the tear strength, tensile strength, elongation at break, weather resistance, and heat aging resistance of weather-resistant chlorinated polyethylene rubber composition 1 and weather-resistant chlorinated polyethylene rubber composition 2 are better than those of weather-resistant chlorinated polyethylene rubber composition 3 and weather-resistant chlorinated polyethylene rubber composition 4.

[0029] In the preparation method of weather-resistant chlorinated polyethylene rubber composition 3, an aqueous solution of magnesium chloride hexahydrate was not added when preparing hybrid modified chlorinated polyethylene rubber, that is, magnesium hydroxide was not generated in situ on the surface of hybrid modified chlorinated polyethylene rubber. Instead, magnesium hydroxide was added separately during mixing and vulcanization, which resulted in the problem of magnesium hydroxide being difficult to disperse. This led to uneven dispersion of magnesium methacrylate generated in situ, which affected the crosslinking effect of magnesium methacrylate. In the preparation method of weather-resistant chlorinated polyethylene rubber composition 4, carbon black and methacrylic acid were not premixed. Instead, carbon black and methacrylic acid were added separately during mixing and vulcanization. This resulted in the problem of difficult dispersion of methacrylic acid, which led to uneven dispersion of the in-situ generated magnesium methacrylate and affected the crosslinking effect of magnesium methacrylate. In summary, in the preparation methods of weather-resistant chlorinated polyethylene rubber composition 1 and weather-resistant chlorinated polyethylene rubber composition 2, combining magnesium hydroxide and silicon dioxide together on the surface of chlorinated polyethylene rubber powder, and pre-binding methacrylic acid to the carbon black surface via hydrogen bonding, followed by mixing and vulcanization, yields better results than adding magnesium hydroxide and methacrylic acid separately. Analysis shows that, firstly, the interaction between magnesium ions and silica sol increases the coating amount of silica sol on the surface of chlorinated polyethylene rubber, thereby increasing the amount of silicon dioxide generated on the surface of chlorinated polyethylene rubber; secondly, this method promotes the dispersion of magnesium hydroxide and methacrylic acid, forming a uniform interpenetrating network of siloxane and rubber powder particles; and thirdly, this method utilizes the interaction between carbon black and methacrylic acid, as well as the high specific surface area of ​​carbon black, to generate magnesium methacrylate in situ on the carbon black surface (the high specific surface area of ​​carbon black promotes the in-situ generation of magnesium methacrylate), and cross-links it in situ on the carbon black surface, thereby enhancing the reinforcing effect of carbon black.

Claims

1. A method for preparing a weather-resistant chlorinated polyethylene rubber composition, characterized in that, Includes the following steps: Preparation of hybrid modified chlorinated polyethylene rubber, including premixing, compounding and vulcanization; The preparation of hybrid modified chlorinated polyethylene rubber involves mixing distilled water, sodium dodecylbenzenesulfonate, and chlorinated polyethylene rubber powder, stirring at room temperature, and continuing to stir while adding methyl orthosilicate dropwise. After the addition is complete, an aqueous solution of magnesium chloride hexahydrate is added dropwise. After the addition is complete, the pH value is adjusted to 12.8-13.2, and the mixture is stirred at 68-72°C. The mixture is then filtered, the filter residue is collected, washed, and vacuum dried to obtain hybrid modified chlorinated polyethylene rubber. The premixing process involves mixing distilled water and methacrylic acid, stirring at room temperature, adding carbon black, stirring, and then vacuum drying to obtain the premixed carbon black.

2. The method for preparing the weather-resistant chlorinated polyethylene rubber composition according to claim 1, characterized in that, In the preparation of the hybrid modified chlorinated polyethylene rubber, the mass ratio of water, sodium dodecylbenzenesulfonate, chlorinated polyethylene rubber powder, methyl orthosilicate, and magnesium chloride hexahydrate aqueous solution is 20000-22000:4-5:2000:80-90:500-550.

3. The method for preparing the weather-resistant chlorinated polyethylene rubber composition according to claim 1, characterized in that, In the preparation of the hybrid modified chlorinated polyethylene rubber, the addition time of methyl orthosilicate is 1.5-2 hours. When adding an aqueous solution of magnesium chloride hexahydrate, the addition time is 1.5-2 hours. The stirring time is 2-2.5 hours when stirring at 68-72℃.

4. The method for preparing the weather-resistant chlorinated polyethylene rubber composition according to claim 1, characterized in that, In the preparation of the hybrid modified chlorinated polyethylene rubber, the chlorine content of the chlorinated polyethylene rubber powder is 36% by mass, and the manufacturer is Weifang Shuoyi Chemical Co., Ltd., with the grade CM3650. The median particle size of the chlorinated polyethylene rubber powder is 280-320 μm; The mass fraction of magnesium chloride hexahydrate in the aqueous solution of the aforementioned magnesium chloride hexahydrate is 18-22%.

5. The method for preparing the weather-resistant chlorinated polyethylene rubber composition according to claim 1, characterized in that, During the premixing process, the mass ratio of distilled water, methacrylic acid, and carbon black is 3000-3500:180-200:2000.

6. The method for preparing the weather-resistant chlorinated polyethylene rubber composition according to claim 1, characterized in that, During the premixing process, the carbon black grade is carbon black N550.

7. The method for preparing the weather-resistant chlorinated polyethylene rubber composition according to claim 1, characterized in that, The mixing and vulcanization process involves adding hybrid modified chlorinated polyethylene rubber and lead stearate to an open mill and mixing for 85-95 seconds. Premixed carbon black is then added and mixed for 235-245 seconds. Antioxidant RD, calcium carbonate, magnesium oxide, and plasticizer TOTM are added and mixed for 145-155 seconds. Vulcanizing agent DCP is added and mixed for 115-125 seconds. The mixture is then passed through a thin pass, formed into triangular sheets, and stored at room temperature to obtain a compound. This compound is then added to a flat vulcanizing machine for vulcanization. After vulcanization, a weather-resistant chlorinated polyethylene rubber composition is obtained.

8. The method for preparing the weather-resistant chlorinated polyethylene rubber composition according to claim 7, characterized in that, During the mixing and vulcanization process, the mass ratio of hybrid modified chlorinated polyethylene rubber, premixed carbon black, calcium carbonate, lead stearate, magnesium oxide, plasticizer TOTM, vulcanizing agent DCP, and antioxidant RD is 98-102:54-56:19-21:2.8-3.2:9.8-10.2:29-31:2.8-3.2:1.4-1.

6.

9. The method for preparing the weather-resistant chlorinated polyethylene rubber composition according to claim 7, characterized in that, During the mixing and vulcanization process, the roll temperature of the open mill during mixing is 78-82℃, and the roll gap is adjusted to 0.9-1mm. The roll gap of a thin-walled open mill is 0.5-0.6 mm; The storage time at room temperature is 23-25 ​​hours; The vulcanization temperature is 165-175℃, and the vulcanization time is 14-16 minutes.

10. A weather-resistant chlorinated polyethylene rubber composition prepared by the preparation method according to any one of claims 1-9.

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