A colored sidewall rubber and its processing method
A phased mixing process with controlled addition of colorants and additives in tire sidewall rubber production addresses cross-production contamination and variation, ensuring uniform color distribution and reduced defects.
Patent Information
- Application Number
- CN202310633590.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-05-31
- Publication Date
- 2025-07-15
- Estimated Expiration
- 2043-05-31
AI Technical Summary
During the rubber processing process, adding various colors of colored rubber causes colored rubber to discolor due to residual in the kneader during cross-production, and cleaning is time-consuming and labor-intensive.
The method of adding colorants in batches is adopted, combined with the four-stage kneading process, kaolin, resin, vulcanizing agent and accelerator are added at the plasticizing and different kneading stages to ensure uniform dispersion of the colorant and avoid adhesion. The pollution and discoloration risks of colored rubber cross-production are reduced through optimized processing technology.
The uniform dispersion of colored rubber is achieved, the macular defect rate of colored tire sidewall rubber is reduced, the kneading machine is avoided, and the production efficiency and product quality are improved.
Smart Images
Figure BDA0004259102890000101
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of rubber production, and particularly to a colored sidewall rubber and a processing method thereof. Background Art
[0002] With the continuous improvement of customers' requirements for the appearance of tires, various colorants are added during the processing of sidewall rubber. However, after adding various colorants, there will be a problem that the colored rubber changes color due to residues in the kneader during cross-production of different color compounds, and it is time-consuming and laborious to manually clean the residues in the kneader. Therefore, in view of the above problems, there is an urgent need to develop a new processing method for colored sidewall rubber. Summary of the Invention
[0003] The present invention provides a colored sidewall rubber and a processing method thereof. The specific implementation manners are as follows:
[0004] A processing method for colored sidewall rubber, the processing method includes a plasticizing process and four-stage mixing processes; during the plasticizing process, the colorant is added in multiple times; kaolin is added respectively in the first-stage mixing process and the second-stage mixing process; the resin is added after the other materials are dispersed in the second-stage mixing process;
[0005] In the third-stage mixing process, a vulcanizing agent is added, and in the fourth-stage mixing process, an accelerator is added;
[0006] When the resin is added in the second-stage mixing process, the mixing temperature is 110°C - 120°C;
[0007] During the second-stage mixing process to the fourth-stage mixing process, the addition sequence of the masterbatch is as follows: first add part of the masterbatch, then add the compounding agents, and finally add the remaining masterbatch;
[0008] During the second-stage mixing process to the fourth-stage mixing process, the addition sequence of the rubber compound is as follows: first add two-thirds of the masterbatch from the previous mixing process, then add the compounding agents and mix, and finally add the remaining one-third of the masterbatch;
[0009] The plasticizing process is as follows: (1) Plasticize natural rubber on an open mill for 10 - 20 min;
[0010] (2) After plasticizing, add one-third of the colorant and mix for 10 min, then cut the rubber left and right 5 - 10 times;
[0011] (3) Then add one-third of the colorant and mix for 10 min, and cut the rubber left and right 5 - 10 times each;
[0012] (4) Add the last one-third of the colorant and mix for 10 min, and cut the rubber left and right 5 - 10 times to obtain the dyed plasticized rubber;
[0013] Each stage of the four-stage mixing process includes an internal mixing process and an open mixing process;
[0014] The internal mixing process in the first-stage mixing process is as follows: At 140 - 150 °C, add the plasticized rubber obtained from the plasticizing process, chlorobutyl rubber, ethylene propylene diene monomer rubber, as well as silica and half of the dosage of kaolin into the kneader, mix for 100 - 400 s, and then add titanium dioxide and mix for 100 - 200 s;
[0015] The internal mixing process in the second-stage mixing process is as follows: First, add two-thirds of the masterbatch rubber from the first-stage mixing process, and then add compounding agents, which include: the remaining kaolin, stearic acid, protective wax, antioxidant. Finally, add the remaining one-third of the masterbatch rubber and mix for 100 - 300 s. During mixing, due to the shearing of the rubber compound with the upper ram and rotor, the temperature will gradually rise from room temperature. When the temperature rises to 110 - 120 °C, add resin and mix for 80 - 100 s, and then mix with the ram until it is discharged at 140 - 150 °C.
[0016] In addition, the present invention also provides a colored sidewall rubber obtained by the above processing method;
[0017] The colored sidewall rubber includes the following components: natural rubber 30 - 50 phr, chlorobutyl rubber 30 - 50 phr, ethylene propylene diene monomer rubber 10 - 30 phr, silica 1 - 10 phr, kaolin 10 - 60 phr, titanium dioxide 10 - 30 phr, colorant 1 - 15 phr, stearic acid 0.5 - 3 phr, high-temperature protective wax 0 - 1 phr, low-temperature protective wax 1 - 3 phr, non-staining antioxidant 0.5 - 2 phr, phenolic resin 1 - 5 phr, vulcanizing agent 1 - 2.5 phr, accelerator 0.5 - 2 phr.
[0018] Due to the adoption of the above technical solutions, the beneficial technical effects of the present invention are:
[0019] 1. In the first-stage plasticizing process of the present invention, a colorant is added and combined with natural rubber in the premixing stage. Then, after the four-stage mixing process, the colorant is evenly dispersed. At the same time, after the resin is added, it is quickly softened and dispersed, and the rubber compound will not adhere to the positions in contact with the kneader, minimizing the risk of contamination and color change caused by cross-production of the colored sidewall rubber;
[0020] 2. In the third-stage mixing process of the present invention, a vulcanizing agent is added, and in the fourth-stage mixing process, an accelerator is added. This not only ensures the dispersion of sulfur through two-stage mixing in the final-stage masterbatch rubber and the final compound, but also avoids the accelerating effect of the accelerator on sulfur at high temperatures, preventing premature cross-linking, ensuring processing safety, and avoiding the appearance of yellow spots on the colored sidewall rubber. Specific Embodiments
[0021] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.
[0022] A processing method for colored sidewall rubber, the processing method includes a plasticizing process and a four-stage mixing process; in the plasticizing process, the colorant is added in multiple times; kaolin is added in the first-stage mixing process and the second-stage mixing process respectively; the resin is added after the other materials are dispersed in the second-stage mixing process. The present invention optimizes the process of mixing the colorant, moves the light-colored natural rubber and the colorant forward, plasticizes on an open mill to produce dyed plasticized rubber, and then mixes the dyed plasticized rubber with other raw rubbers and compounding agents. Since the colorant has combined with the rubber in the premixing stage, the dyed plasticized rubber and other compounding agents are evenly dispersed. After adding the resin, the resin quickly softens and disperses, and no longer adheres to the upper plug, rotor, and mixing chamber of the kneader, eliminating the need for time-consuming cleaning, and minimizing the risk of pollution and discoloration caused by cross-production of different colored sidewall rubbers.
[0023] Example 1
[0024] The colored sidewall rubber includes: 45 phr of natural rubber, 45 phr of chlorinated butyl rubber, 10 phr of ethylene propylene diene monomer rubber, 5 phr of white carbon black, 40 phr of kaolin, 20 phr of titanium dioxide, 9 phr of colorant, 2 phr of stearic acid, 0.5 phr of high-temperature protective wax, 2 phr of low-temperature protective wax, 1 phr of non-staining antioxidant, 3 phr of phenolic resin, 1.5 phr of vulcanizing agent, 1 phr of accelerator.
[0025] The processing method is as follows:
[0026] Plasticizing process: Mix on an open mill (rotation speed 35 rpm; roll gap 8 mm), plasticize the natural rubber on the open mill for 15 min, and cut the rubber on both sides 10 times each for plasticization; after plasticization, add 1 / 3 of the colorant dosage (3 phr of colorant), mix for 10 min, clean, and cut the rubber on both sides 10 times each; then add another 1 / 3 of the colorant dosage (3 phr of colorant), mix for 10 min, clean, and cut the rubber on both sides 10 times each; finally, add the cleaned colorant together with the last 1 / 3 of the colorant dosage (3 phr of colorant), mix for 10 min, clean, and cut the rubber on both sides 10 times each, and then take off the sheet to obtain dyed plasticized rubber.
[0027] The first-stage mixing process: (1) The first-stage masterbatch kneader process: Add the pre-dispersed dyed plasticized rubber, chlorobutyl rubber, ethylene propylene diene monomer (EPDM), silica, and 1 / 2 of the dosage of kaolin (20 phr of kaolin) that have been weighed into the kneader, and conduct plug mixing for 300 s (at a rotational speed of 25 rpm). Lift the upper plug, clean, add titanium dioxide and conduct plug mixing for 150 s (at a rotational speed of 25 rpm). Lift the upper plug, clean, and conduct plug mixing until it is discharged at 145 °C; (2) The first-stage masterbatch open mill process (rotational speed 35 rpm; roll gap 7 mm): Drop the roll 4 times (2 min), make 3 triangle packs (8 min), thin pass 3 times (8 min), and take off the sheet.
[0028] The second-stage mixing process: (1) The second-stage masterbatch kneader process: First, add approximately 2 / 3 of the dosage of the masterbatch obtained from the first-stage mixing process, the remaining 1 / 2 of the dosage of kaolin (20 phr of kaolin), stearic acid, high-temperature protective wax, low-temperature protective wax, and non-discoloring antioxidant. Then add 1 / 3 of the dosage of the masterbatch obtained from the first-stage mixing process, and conduct plug mixing for 200 s (at a rotational speed of 25 rpm). When the temperature rises to 115 °C, lift the upper plug, clean, add phenolic resin and conduct plug mixing for 90 s (at a rotational speed of 25 rpm). Lift the upper plug, clean, and conduct plug mixing until it is discharged at 145 °C; (2) The second-stage masterbatch open mill process is the same as the first-stage masterbatch open mill process.
[0029] The third-stage mixing process: (1) The third-stage masterbatch kneader process: First, add approximately 2 / 3 of the dosage of the masterbatch obtained from the second-stage mixing process, sulfur. Then add 1 / 3 of the dosage of the masterbatch obtained from the second-stage mixing process, and conduct plug mixing for 90 s (at a rotational speed of 25 rpm). Lift the upper plug, clean, conduct plug mixing for 55 s (at a rotational speed of 25 rpm). Lift the upper plug, clean, and conduct plug mixing until it is discharged at 125 °C; (2) The third-stage masterbatch open mill process: (rotational speed 35 rpm; roll gap 7 mm): Drop the roll 5 times (3 min), make 4 triangle packs (10 min), thin pass 4 times (10 min), and take off the sheet;
[0030] The fourth-stage mixing process: (1) The fourth-stage masterbatch kneader process: First, add approximately 2 / 3 of the dosage of the masterbatch obtained from the third-stage mixing process, accelerator. Then add 1 / 3 of the dosage of the masterbatch obtained from the third-stage mixing process, and conduct plug mixing for 50 s (25 rpm). Lift the upper plug, clean, conduct plug mixing for 30 s (25 rpm). Lift the upper plug, clean, and conduct plug mixing until it is discharged at 105 °C; (2) The fourth-stage masterbatch open mill process is the same as the third-stage masterbatch open mill process.
[0031] Example 2
[0032] The colored sidewall rubber compound includes: 30 phr of natural rubber, 50 phr of chlorinated butyl rubber, 20 phr of ethylene propylene diene monomer rubber, 1 phr of precipitated silica, 10 phr of kaolin, 10 phr of titanium dioxide, 1 phr of colorant, 0.5 phr of stearic acid, 1 phr of low-temperature protective wax, 0.5 phr of antioxidant, 1 phr of phenolic resin, 1 phr of vulcanizing agent, and 0.5 phr of accelerator.
[0033] The processing method is as follows:
[0034] Plasticizing process: Use an open two-roll mill for mixing (rotation speed 30 rpm; roll gap 7 mm). Plasticize the natural rubber on the two-roll mill for 10 min, with 5 cuts on each side for plasticization; after plasticization, add 1 / 2 dosage of the colorant (0.5 phr of colorant), mix for 10 min, clean, make 5 cuts on each side; then add another 1 / 2 dosage of the colorant (0.5 phr of colorant), mix for 10 min, clean, and make 5 cuts on each side before taking off the sheet to obtain the dyed plasticized rubber.
[0035] The first-stage mixing process: (1) The first-stage masterbatch kneader process: Add the weighed pre-dispersed dyed plasticized rubber, chlorinated butyl rubber, ethylene propylene diene monomer rubber, precipitated silica, and 1 / 2 dosage of kaolin (5 phr of kaolin) to the kneader, press the plug for mixing for 100 s (rotation speed 35 rpm), lift the top plug, clean, add titanium dioxide and press the plug for mixing for 100 s (rotation speed 35 rpm), lift the top plug, clean, and press the plug for mixing until it is discharged at 140 °C; (2)
[0036] The first-stage masterbatch two-roll mill process (rotation speed 30 rpm; roll gap 6 mm): Drop the roll 4 times (1 min), make 3 triangle packs (5 min), thin pass 3 times (5 min), and take off the sheet.
[0037] The second-stage mixing process: (1) The second-stage masterbatch kneader process: First add about 2 / 3 dosage of the masterbatch obtained from the first-stage mixing process, the remaining 1 / 2 dosage of kaolin (5 phr of kaolin), stearic acid, low-temperature protective wax, and non-staining antioxidant, then add 1 / 3 dosage of the masterbatch obtained from the first-stage mixing process, press the plug for mixing for 100 s (rotation speed 35 rpm), when the temperature rises to 110 °C, lift the top plug, clean, add phenolic resin and press the plug for mixing for 80 s (rotation speed 35 rpm), lift the top plug, clean, and press the plug for mixing until it is discharged at 145 °C; (2) The second-stage masterbatch two-roll mill process is the same as the first-stage masterbatch two-roll mill process.
[0038] The third-stage mixing process: (1) The process of the third-stage masterbatch kneader: First, add about 2 / 3 of the masterbatch obtained from the second-stage mixing process, sulfur, then add 1 / 3 of the masterbatch obtained from the second-stage mixing process, press the ram and mix for 80 s (rotation speed is 35 rpm), lift the upper ram, clean, press the ram and mix for 50 s (rotation speed is 35 rpm), lift the upper ram, clean, and press the ram and mix until it is discharged at 120 °C; (2) The process of the third-stage masterbatch open mill: (rotation speed 30 rpm; roll gap 6 mm): Drop the disk 5 times (2 min), make 4 triangular bales (8 min), thin pass 4 times (8 min), and take off the sheet.
[0039] The fourth-stage mixing process: (1) The process of the fourth-stage masterbatch kneader: First, add about 2 / 3 of the masterbatch obtained from the third-stage mixing process, accelerator, then add 1 / 3 of the masterbatch obtained from the third-stage mixing process, press the ram and mix for 40 s (35 rpm), lift the upper ram, clean, press the ram and mix for 20 s (35 rpm), lift the upper ram, clean, and press the ram and mix until it is discharged at 100 °C; (2) The process of the fourth-stage masterbatch open mill is the same as that of the third-stage masterbatch open mill.
[0040] Example 3
[0041] The colored sidewall rubber includes: 50 phr of natural rubber, 30 phr of chlorinated butyl rubber, 20 phr of ethylene propylene diene monomer rubber, 10 phr of white carbon black, 60 phr of kaolin, 30 phr of titanium dioxide, 15 phr of colorant, 3 phr of stearic acid, 1 phr of high-temperature protective wax, 3 phr of low-temperature protective wax, 2 phr of non-staining antioxidant, 5 phr of phenolic resin, 2.5 phr of vulcanizing agent, and 2 phr of accelerator.
[0042] The processing method is as follows:
[0043] Plasticizing process: Use an open mill for mixing (rotation speed 40 rpm; roll gap 10 mm), plasticize the natural rubber on the open mill for 20 min, cut the rubber on both sides 5 times for plasticization; after plasticization, add 1 / 4 of the colorant dosage (5 phr of colorant), mix for 10 min, clean, cut the rubber on both sides 5 times; then add 1 / 4 of the colorant dosage (5 phr of colorant), mix for 10 min, clean, cut the rubber on both sides 5 times; then add 1 / 4 of the colorant dosage (5 phr of colorant), mix for 10 min, clean, cut the rubber on both sides 5 times; finally, add the cleaned colorant and the last 1 / 4 of the colorant dosage (5 phr of colorant), mix for 10 min, clean, cut the rubber on both sides 5 times and then take off the sheet to obtain the dyed plasticized rubber.
[0044] The first-stage mixing process: (1) The first-stage masterbatch kneader process: Add the pre-dispersed dyed plasticized rubber, chlorinated butyl rubber, ethylene propylene diene monomer rubber, silica, and 1 / 2 of the kaolin (30 phr of kaolin) in the weighed amount to the kneader, carry out plug mixing for 400 s (rotation speed is 15 rpm), lift the top plug, clean, add titanium dioxide and carry out plug mixing for 200 s (rotation speed is 15 rpm), lift the top plug, clean, and carry out plug mixing until it is discharged at 150 °C; (2) The first-stage masterbatch open mill process (rotation speed 40 rpm; roll gap 8 mm): Drop the roll 4 times (2 min), make triangular bales 3 times (10 min), thin pass 3 times (10 min), and take off the sheet.
[0045] The second-stage mixing process: (1) The second-stage masterbatch kneader process: First add about 2 / 3 of the masterbatch obtained from the first-stage mixing process, the remaining 1 / 2 of the kaolin (30 phr of kaolin), stearic acid, high-temperature protective wax, low-temperature protective wax, non-staining antioxidant, and then add 1 / 3 of the masterbatch obtained from the first-stage mixing process, carry out plug mixing for 300 s (rotation speed is 15 rpm), when the temperature rises to 120 °C, lift the top plug, clean, add phenolic resin and carry out plug mixing for 100 s (rotation speed is 15 rpm), lift the top plug, clean, and carry out plug mixing until it is discharged at 150 °C; (2) The second-stage masterbatch open mill process is the same as the first-stage masterbatch open mill process.
[0046] The third-stage mixing process: (1) The third-stage masterbatch kneader process: First add about 2 / 3 of the masterbatch obtained from the second-stage mixing process, sulfur, and then add 1 / 3 of the masterbatch obtained from the second-stage mixing process, carry out plug mixing for 100 s (rotation speed is 15 rpm), lift the top plug, clean, carry out plug mixing for 60 s (rotation speed is 15 rpm), lift the top plug, clean, and carry out plug mixing until it is discharged at 130 °C; (2) The third-stage masterbatch open mill process: (rotation speed 40 rpm; roll gap 8 mm): Drop the roll 5 times (4 min), make triangular bales 4 times (15 min), thin pass 4 times (15 min), and take off the sheet;
[0047] The fourth-stage mixing process: (1) The fourth-stage masterbatch kneader process: First add about 2 / 3 of the masterbatch obtained from the third-stage mixing process, accelerator, and then add 1 / 3 of the masterbatch obtained from the third-stage mixing process, carry out plug mixing for 60 s (15 rpm), lift the top plug, clean, carry out plug mixing for 40 s (15 rpm), lift the top plug, clean, and carry out plug mixing until it is discharged at 110 °C; (2) The fourth-stage masterbatch open mill process is the same as the third-stage masterbatch open mill process.
[0048] Example 4
[0049] The colored sidewall rubber compound includes: 45 phr of natural rubber, 25 phr of chlorinated butyl rubber, 30 phr of ethylene propylene diene monomer rubber, 7 phr of precipitated silica, 30 phr of kaolin, 20 phr of titanium dioxide, 12 phr of colorant, 1 phr of stearic acid, 0.5 phr of high-temperature protective wax, 2 phr of low-temperature protective wax, 1 phr of non-discoloring antioxidant, 2 phr of phenolic resin, 2 phr of vulcanizing agent, and 1.5 phr of accelerator.
[0050] The processing method is as follows:
[0051] Plasticizing process: Use an open two-roll mill for mixing (rotation speed 40 rpm; roll gap 9 mm). Plasticize the natural rubber on the two-roll mill for 18 min, with 10 cuts on each side for plasticization. After plasticization, add 1 / 3 of the colorant dosage (5 phr of colorant), mix for 10 min, clean, and make 10 cuts on each side; then add another 1 / 3 of the colorant dosage (5 phr of colorant), mix for 10 min, clean, and make 10 cuts on each side; finally, add the cleaned colorant together with the last 1 / 3 of the colorant dosage (5 phr of colorant), mix for 10 min, clean, and make 10 cuts on each side, and then take off the sheet to obtain the dyed plasticized rubber.
[0052] First-stage mixing process: (1) First-stage masterbatch kneader process: Add the weighed pre-dispersed dyed plasticized rubber, chlorinated butyl rubber, ethylene propylene diene monomer rubber, precipitated silica, and 1 / 2 of the kaolin dosage (15 phr of kaolin) to the kneader, press the plug and mix for 200 s (rotation speed 20 rpm), lift the upper plug, clean, add titanium dioxide, press the plug and mix for 100 s (rotation speed 30 rpm), lift the upper plug, clean, and press the plug and mix until discharged at 140 °C; (2) First-stage masterbatch two-roll mill process (rotation speed 35 rpm; roll gap 7 mm): Drop the roll 4 times (2 min), make 3 triangle bales (8 min), thin pass 3 times (8 min), and then take off the sheet.
[0053] Second-stage mixing process: (1) Second-stage masterbatch kneader process: First, add about 1 / 2 of the masterbatch obtained from the first-stage mixing process, the remaining 1 / 2 of the kaolin dosage (15 phr of kaolin), stearic acid, high-temperature protective wax, low-temperature protective wax, and non-discoloring antioxidant, then add another 1 / 2 of the masterbatch obtained from the first-stage mixing process, press the plug and mix for 150 s (rotation speed 30 rpm). When the temperature rises to 110 °C, lift the upper plug, clean, add phenolic resin, press the plug and mix for 85 s (rotation speed 25 rpm), lift the upper plug, clean, and press the plug and mix until discharged at 140 °C; (2) The second-stage masterbatch two-roll mill process is the same as the first-stage masterbatch two-roll mill process.
[0054] The third stage mixing process: (1) The third stage masterbatch kneader process: First, add about 1 / 2 of the masterbatch rubber obtained from the second stage mixing process, sulfur, then add another 1 / 2 of the masterbatch rubber obtained from the second stage mixing process, press the plug and mix for 90 s (rotation speed is 25 rpm), lift the upper plug, clean, press the plug and mix for 55 s (rotation speed is 25 rpm), lift the upper plug, clean, and press the plug and mix until it is discharged at 125 °C; (2) The third stage masterbatch open mill process: (rotation speed 35 rpm; roll gap 7 mm): Drop the roll 5 times (3 min), make 4 triangle bales (10 min), thin pass 4 times (10 min), and take off the sheet.
[0055] The fourth stage mixing process: (1) The fourth stage masterbatch kneader process: First, add about 1 / 2 of the masterbatch rubber obtained from the third stage mixing process, accelerator, then add another 1 / 2 of the masterbatch rubber obtained from the third stage mixing process, press the plug and mix for 50 s (25 rpm), lift the upper plug, clean, press the plug and mix for 30 s (25 rpm), lift the upper plug, clean, and press the plug and mix until it is discharged at 105 °C; (2) The fourth stage masterbatch open mill process is the same as the third stage masterbatch open mill process.
[0056] Comparative Example 1
[0057] Compared with Example 1, the colorant is added in the first stage mixing process, and the other parts are exactly the same.
[0058] Comparative Example 2
[0059] Compared with Example 1, both sulfur and accelerator are added in the fourth stage mixing process, and the other parts are exactly the same.
[0060] Comparative Example 3
[0061] Compared with Example 1, the colorant is added all at once during the plasticizing process, and the other parts are exactly the same.
[0062] Comparative Example 4
[0063] Compared with Example 1, phenolic resin is added together with the remaining 1 / 2 of the dosage of kaolin (20 phr of kaolin), stearic acid, high temperature protective wax, low temperature protective wax, and non-staining antioxidant, and the other parts are exactly the same.
[0064] Observe whether there is adhesion in the kneader during the processing of Examples 1 - 3 and Comparative Examples 1 - 4, and the test results of the S element content of the colored sidewall rubbers obtained from Examples 1 - 3 and Comparative Examples 1 - 4 are shown in Table 1.
[0065] Table 1 Test results of the S element content of the colored sidewall rubbers obtained from Examples 1 - 4 and Comparative Examples 1 - 4
[0066]
[0067] As can be seen from the above examples and comparative examples, in Examples 1-4, the colored sidewall rubber prepared no longer adheres to the upper plug, rotor, and mixing chamber of the kneader, eliminating the need for time-consuming cleaning. This minimizes the potential for contamination and color change caused by cross-production. At the same time, the pigment is evenly dispersed, resulting in a uniform color for the produced colored rubber, without lumps or color differences. After adjusting the processing technology, the overall defect rate of the yellow spots on the sidewall of the colored tire is reduced to a minimum of approximately 400 ppm / month. The colorant is added in batches during the premixing stage. By the premixing stage, the colorant has already combined with the rubber, and the dyed plasticized rubber and other compounding agents are evenly dispersed. After adding the resin, the resin quickly softens and disperses. Additionally, sulfur is added in the third stage of mixing, and the accelerator is added during the fourth stage of mixing to avoid premature crosslinking and ensure the safety of processing.
[0068] Due to the adoption of the above technical solutions, the beneficial technical effects of the present invention are as follows:
[0069] 1. During the plasticizing process, the dyed plasticized rubber is prepared and dispersed in advance to ensure the uniformity of the colorant dispersion among different batches.
[0070] 2. Since the colored rubber uses the light-colored inorganic filler kaolin, which has poor reinforcing effect, a large amount is generally used to ensure the physical properties of the rubber compound. If all of it is added during the first stage of mixing, a "slipping" phenomenon of not eating powder will occur during the kneading process of the kneader, resulting in the rotor being unable to effectively shear the mixed rubber and normal production being impossible. Therefore, the kaolin is evenly divided and added in two stages to ensure normal mixing and good dispersion each time.
[0071] 3. The antioxidant is added during the second stage of mixing, which can make the macromolecular chains of the rubber in the first stage break more easily, reduce the Mooney viscosity, and improve the processing performance. When added together with 1 / 2 of the kaolin dosage in the second stage of mixing, it can prevent the antioxidant from melting with the rising temperature and causing a "slipping" phenomenon between the rotor and the mixed rubber.
[0072] 4. The softening point of the resin is generally above 90°C. If it is added synchronously with other materials during feeding, it may be carried into the "dead corner" position of the kneader during the shearing process of the rubber compound. As the temperature rises, the resin will gradually soften and flow, coating the rubber compound and other compounding agents, especially the colorant, resulting in color differences. Here, the resin is added after the other materials are dispersed during the second stage of mixing (especially when adding the resin in the temperature range of 110°C - 120°C). This can ensure the dispersion of the colorant first. After adding, the resin quickly softens and disperses into the mixed rubber, avoiding the above problems.
[0073] 5. The vulcanizing agent and accelerator are added separately. The vulcanizing agent is added during the third-stage mixing process, and the accelerator is added during the fourth-stage mixing process. In this way, on the one hand, the vulcanizing agent is dispersed twice, which can avoid the yellow spot discoloration caused by uneven dispersion. At the same time, in the absence of the accelerating effect of the accelerator, the masterbatch can be processed to 120°C - 130°C during the third-stage mixing process of adding the vulcanizing agent without crosslinking, ensuring the safety of processing.
[0074] 6. During each stage of the mixing process, when producing the rubber compound, first add 2 / 3 of the previous-stage masterbatch, then add compounding agents such as chemicals, and then add 1 / 3 of the previous-stage masterbatch, so that the compounding agents such as chemicals are surrounded by rubber compounds at both the upper and lower ends. Under the action of the top plug, rotor, and mixing chamber wall of the kneader, the chemicals are frictionally dispersed by the rubber compound, avoiding agglomeration and uneven dispersion caused by entering the "dead corner" position of the kneader.
[0075] In addition, it should be understood that although this specification is described according to the embodiments, not each embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.
Claims
1. A processing method for a colored sidewall rubber, characterized in that, The processing method includes a plasticating process and a four-stage mixing process; in the plasticating process, the colorant is added in multiple times; kaolin is added in the first-stage mixing process and the second-stage mixing process respectively; the resin is added after the other materials are dispersed in the second-stage mixing process. The vulcanizing agent is added in the third-stage mixing process, and the accelerator is added in the fourth-stage mixing process. During the second-stage mixing process to the fourth-stage mixing process, the addition order of the masterbatch is as follows: first add part of the masterbatch, then add the compounding agents, and finally add the remaining masterbatch. During the second-stage mixing process to the fourth-stage mixing process, the addition order of the rubber compound is as follows: first add two-thirds of the masterbatch from the previous mixing process, then add the compounding agents and mix, and finally add the remaining one-third of the masterbatch. The colored sidewall rubber comprises the following components: 30-50 phr of natural rubber, 30-50 phr of chlorinated butyl rubber, 10-30 phr of ethylene propylene diene monomer rubber, 1-10 phr of white carbon black, 10-60 phr of kaolin, 10-30 phr of titanium dioxide, 1-15 phr of colorant, 0.5-3 phr of stearic acid, 0-1 phr of high-temperature protective wax, 1-3 phr of low-temperature protective wax, 0.5-2 phr of non-staining antioxidant, 1-5 phr of phenolic resin, 1-2.5 phr of vulcanizing agent, 0.5-2 phr of accelerator.
2. The processing method of a colored sidewall rubber according to claim 1, characterized in that When the resin is added in the second-stage mixing process, the mixing temperature is 110°C - 120°C.
3. The processing method of a color sidewall rubber according to claim 1, wherein The plasticating process is as follows: (1) Plasticate the natural rubber on an open mill for 10-20 min. (2) After plasticating, add one-third of the colorant and mix for 10 min, and then cut the rubber left and right for 5-10 times. (3) Add another one-third of the colorant and mix for 10 min, and then cut the rubber left and right for 5-10 times each. (4) Add the last one-third of the colorant and mix for 10 min, and then cut the rubber left and right for 5-10 times to obtain the dyed plasticated rubber.
4. The processing method of a colored sidewall rubber according to claim 1, characterized in that Each stage of the four-stage mixing process includes an internal mixing process and an open mixing process. The specific internal mixing process in the first-stage mixing process is as follows: at 140-150°C, add the plasticated rubber obtained from the plasticating process, chlorinated butyl rubber, ethylene propylene diene monomer rubber, white carbon black, and one-half of the kaolin dosage into a kneader, mix for 100-400 s, and then add titanium dioxide and mix for 100-200 s.
5. The processing method of a colored sidewall rubber according to claim 4, characterized in that, The specific internal mixing process in the second-stage mixing process is as follows: first add two-thirds of the masterbatch from the first-stage mixing process, then add the compounding agents, and the compounding agents include the remaining kaolin, stearic acid, protective wax, antioxidant, and finally add the remaining one-third of the masterbatch, mix for 100-300 s. When the temperature rises to 110-120°C, add the resin and then mix for 80-100 s, and mix with the pressure bolt until it is discharged at 140-150°C.
6. A colored sidewall rubber prepared by the processing method of a colored sidewall rubber according to any one of claims 1-5.
7. The colored sidewall rubber according to claim 6, characterized in that The colored sidewall rubber comprises the following components: natural rubber 30-50 phr, chlorinated butyl rubber 30-50 phr, ethylene propylene diene monomer rubber 10-30 phr, white carbon black 1-10 phr, kaolin 10-60 phr, titanium dioxide 10-30 phr, colorant 1-15 phr, stearic acid 0.5-3 phr, high-temperature protective wax 0-1 phr, low-temperature protective wax 1-3 phr, non-discoloring antioxidant 0.5-2 phr, phenolic resin 1-5 phr, vulcanizing agent 1-2.5 phr, accelerator 0.5-2 phr.
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Patent Citations
Anti-aging discoloration-resistant colored tire sidewall rubber and preparation method thereof
CN113637240A