Mixing method of rubber composition with high wear resistance and low heat generation and rubber composition

Abstract

The invention relates to the technical field of tire rubber mixing, and discloses a mixing method of a high-wear-resistance and low-heat-generation rubber composition, which comprises the following steps of: separately mixing high-molecular-weight natural rubber or butadiene styrene rubber / carbon black mixed high-temperature field and butadiene rubber / white carbon black / silane coupling agent mixed low-temperature field; the technical difficulty of blending rubber compositions with different temperature field requirements is effectively solved; meanwhile, the Mooney viscosity of the rubber composition can be greatly reduced by utilizing the high shearing capacity of the screw, and the segregation problem of the filler in different rubbers is improved; for the rubber composition without the addition of filling oil, the mixing method can further improve the abrasion performance of the rubber composition; in addition, VOC emission in the rubber composition processing process is effectively reduced through collection and treatment of VOC in the mixing process.

Description

Technical Field

[0001] The invention relates to the technical field of tire rubber mixing, in particular to a mixing method of a high-wear-resistant and low-heat-generating rubber composition and a rubber composition. Background Art

[0002] With the rapid development of the new energy vehicle industry, its market share is also increasing. Due to the weight of the battery of new energy vehicles, the body weight is heavier than that of fuel vehicles. Therefore, the load on the tires is greater, and the problem of the wear resistance of new energy vehicle tires has gradually attracted people's attention.

[0003] To improve the wear performance of the tire tread, it is generally necessary to increase the amount of butadiene rubber or increase the amount of filler. However, this method will affect the tire's grip and heat generation performance, and there may be risks of chipping, falling off, etc. in the later stages of use.

[0004] In order to improve the grip performance and heat generation performance, silica filler is often used to replace part of the carbon black. However, due to the temperature requirements of the silica silanization reaction, the number of processing stages is higher than that of other rubber compositions, which increases energy consumption and VOC emissions, and has an adverse impact on the environment.

[0005] Therefore, a mixing method for a rubber composition with high wear resistance and low heat generation is needed, and the production energy consumption and VOC emission can be reduced.

[0006] The Chinese invention patent (publication number: CN117719086A, publication date: 2024.03.19) discloses a mixing method for a silica-filled rubber composition, which mixes rubber and fine materials separately, and by utilizing the advantages of high shear dispersion efficiency and precise temperature control of the extrusion equipment, the degree of silanization reaction of the silica-filled rubber composition is improved under the premise of reducing the amount of silane coupling agent, and the dispersion of the silica filler is improved. At the same time, the addition of processing oil is eliminated, the wear performance of the highly filled silica rubber composition is improved, and there is no need to repeatedly use the internal mixer for mixing and shearing, reducing the use of electric energy. However, the patent does not involve reducing VOC gas emissions, and the method of the present invention is more suitable for mixing high-wear-resistant and low-heat rubber compositions. Summary of the invention

[0007] The present invention aims at the deficiencies of the prior art and provides a mixing method for a high wear-resistant and low heat generation rubber composition, which can prepare a high wear-resistant and low heat generation rubber composition.

[0008] In order to achieve the above-mentioned purpose, the present invention adopts the following technical solutions: A mixing method for a high wear-resistant and low heat generation rubber composition comprises the following stages: 1) Raw material mixing stage: rubber component 1 and rubber component 2 are mixed in different internal mixers respectively; rubber component 1 is a mixture of butadiene rubber, 10% to 30% carbon black, white carbon black, silane coupling agent, activator, antioxidant and resin; rubber component 2 is a mixture of natural rubber or styrene-butadiene rubber and 70% to 90% carbon black, or a mixture of natural rubber or styrene-butadiene rubber, 70% to 90% carbon black and filler oil; a. Use internal mixer M to mix rubber component 1, heat the mixture to a set temperature, and then discharge it into extruder A; the internal mixer M is set to a discharge temperature of 120-140°C, a speed of 30-60 rpm, and pressurization for 30-60 seconds; b. Use internal mixer N to mix rubber component 2, heat the mixture to a set temperature, and then discharge it into extruder E; the internal mixer N is set to a discharge temperature of 150-160° C., a set speed of 30-60 rpm, and pressurization for 30-60 seconds; 2) Heating stage: a. Setting the screw speed and barrel temperature of extruder A, while mixing the rubber component 1, raising the mixing temperature, and transferring the rubber component 1 to extruder B; the speed of the extruder A is 10-50 rpm, the barrel temperature is 120-150° C., and the outlet thermocouple temperature is 130-140° C.; b. Set the screw speed and barrel temperature of the extruder E to control the mixing temperature while mixing the rubber component 2; the speed of the extruder E is 10-50 rpm, the barrel temperature is 120-150° C., and the outlet thermocouple temperature of the extruder E is 150-170° C.; At the same time, a vacuum pump is used to extract the VOC gas inside the extruder A and the extruder E. The VOC gas extracted by the vacuum pump is effectively treated by the VOC recovery and treatment device; 3) Constant temperature stage: the speed of extruder B is set to 100-200 rpm, the sleeve temperature is set to 100-150°C, the rubber component 1 is kept at a constant temperature in the extruder B, and a vacuum pump is used to extract the VOC gas inside the extruder B. The VOC gas extracted by the vacuum pump is effectively treated by the VOC recovery and treatment device; the rubber component 1 and the rubber component 2 after exhaust are transferred to the extruder C; 4) Component mixing stage: The rubber component 1 and the rubber component 2 are finally mixed in the extruder C to obtain the rubber composition Q. The rotation speed of the extruder C is 15-20 rpm, the sleeve temperature is 110-120° C., and the outlet thermocouple temperature is 125-145° C.; 5) Rubber discharge stage: set the speed of extruder D to 10-25 rpm and the sleeve temperature to 100-120°C, transfer the rubber composition Q in extruder C to extruder D, and finally extrude, sheet and collect the rubber composition Q through extruder D.

[0009] Preferably, the extruder A, extruder B, extruder C and extruder E are single-screw extruders or twin-screw extruders.

[0010] Preferably, the extruder A, extruder B, extruder C and extruder E are twin-screw extruders, and the aspect ratio of the twin screws is 25:1 to 40:1.

[0011] Preferably, the rotation speed of the extruder A and the extruder E is 25-45 rpm; the sleeve temperature of the extruder A is 120-130°C, and the sleeve temperature of the extruder E is 130-150°C.

[0012] Preferably, the rotation speed of the extruder B is 100-150 rpm; the barrel temperature of the extruder B is 110-125°C.

[0013] Preferably, the extruder D is a single screw extruder.

[0014] Preferably, the rotation speed of the extruder D is 15-20 rpm.

[0015] Preferably, the rubber composition 1 stays in the extruder B for no less than 90 seconds, and the total stay time in the extruders A and B is no less than 120 seconds.

[0016] Furthermore, the present invention also discloses a high wear-resistant and low heat generation rubber composition prepared by the mixing method.

[0017] The beneficial effects of the present invention are as follows: the mixing method of the present invention separately mixes the high temperature field of a high molecular weight natural rubber or styrene-butadiene rubber / carbon black mixture and the low temperature field of a butadiene rubber / white carbon black / silane coupling agent mixture, effectively solving the technical difficulty of blending rubber compositions with different temperature field requirements; at the same time, the high shear capacity of the screw can greatly reduce the Mooney viscosity of the rubber composition, improving the segregation problem of fillers in different rubbers; and for a rubber composition without the addition of filler oil, the mixing method can further improve the wear performance of the rubber composition; in addition, the collection and treatment of VOCs during the mixing process effectively reduces the VOC emissions during the processing of the rubber composition. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The present invention is a flow chart of the mixing method of the rubber composition. DETAILED DESCRIPTION

[0019] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] The specific formulations of the reference examples, embodiments and comparative examples are shown in Table 1.

[0021] Table 1 raw materials Comparative Example 1 Comparative Example 2 Example 1 Example 2 Example 3 Natural rubber*1 85 85 85 85 Styrene butadiene rubber*2 80 Butadiene rubber*3 15 15 15 15 20 Carbon black*4 55 50 55 50 50 White carbon black*5 15 15 15 15 15 Silane coupling agent*6 2 2 2 2 2 Filling oil*7 12 0 12 0 0 Other raw materials*8 11.6 11.6 11.6 11.6 11.6 Source of raw materials: *1: The trade name of natural rubber A is TSR10#, Thailand 10# standard rubber.

[0022] *2: The trade name of styrene butadiene rubber B is SBR1723, a product of Shenhua Chemical Industry Co., Ltd.

[0023] *3: The trade name of butadiene rubber C is NdBR40, a product of Sinopec Beijing Yanshan Branch.

[0024] *4: The trade name of carbon black is N234, a product of Cabot Chemicals.

[0025] *5: The trade name of white carbon black is 355MP, a product of Fujian Sanming Zhengyuan Chemical.

[0026] *6: The trade name of silane coupling agent is Si69, a product of Jiangxi Hongbai Company.

[0027] *7: The product name of the filling oil is V700, a product of Ningbo Hansheng Company.

[0028] *8: Other raw materials include 3.0 parts of zinc oxide, 1.0 parts of stearic acid, 1.0 parts of antioxidant TMQ, 1.0 parts of microcrystalline wax, 3 parts of petroleum resin, 0.8 parts of accelerator NS, 1.8 parts of sulfur, totaling 11.6 parts.

[0029] Example 1 The preparation process is as follows: A 25L internal mixer is selected, the temperature rising section extruder A and the extruder E are twin screw extruders, and the twin screw length-diameter ratio is 30:1; the constant temperature section extruder B is a twin screw extruder, and the twin screw length-diameter ratio is 30:1; the mixing section extruder C is a twin screw extruder, and the twin screw length-diameter ratio is 30:1; the rubber discharge section extruder D is a single screw extruder; the vulcanization process uses an internal mixer; the high wear-resistant and low heat generation rubber composition mixing method of the present invention is used for mixing, and the specific steps are as follows: (1) Raw material mixing stage: a. Add butyl rubber, 20% carbon black, white carbon black, silane coupling agent, antioxidant TMQ, stearic acid, zinc oxide, petroleum resin and microcrystalline wax into 25L internal mixer M, rotate at 45rpm, pressurize for 30 seconds; lift the pressure and push the top bolt once, and heat to 125℃ to discharge the rubber; b. Add natural rubber, 80% carbon black and filler oil into 25L internal mixer N, rotate at 45rpm, pressurize for 30 seconds; lift the top bolt once, and heat to 155℃ to discharge the rubber; (2) Heating stage: a. Feed the rubber component 1 discharged from the internal mixer M into the twin-screw extruder A in the heating section using a double-cone feeder, keep the screw speed at 25rpm, set the sleeve temperature to 125℃ and control it within the range of 120-130℃, ensure that the thermocouple temperature at the extruder outlet is within the range of 130-140℃, and set the thermocouple temperature to 135℃; b. Feed the rubber component 2 discharged from the internal mixer N into the twin-screw extruder E in the heating section using a double-cone feeder, keep the screw speed at 25 rpm, set the sleeve temperature at 135°C and control it within the range of 130-140°C, ensure that the thermocouple temperature at the outlet of the extruder E is within the range of 150-160°C, and set the thermocouple temperature to 155°C; (3) Constant temperature stage: the rubber component 1 discharged from the twin-screw extruder A in the temperature rising stage is directly passed into the twin-screw extruder B in the constant temperature stage, the sleeve temperature is set to 115°C and controlled within the range of 110-120°C, and the twin-screw speed is controlled to 125 rpm, ensuring that the residence time of the rubber composition 1 in the extruder B is not less than 90 seconds, and the total residence time in the extruders A and B is not less than 120 seconds; During the heating and constant temperature stages, a vacuum pump is used to extract the VOC gas inside extruder A, extruder B and extruder E. The VOC gas extracted by the vacuum pump is effectively treated by a VOC recovery and treatment device. The treatment methods include solvent spraying, physical or microbial adsorption, etc. Solvent spraying is used here; (4) Component mixing stage: rubber component 1 and rubber component 2 are directly fed to a twin-screw extruder C in a mixing section. The barrel temperature of the extruder C is set to 115°C and controlled within the range of 110 to 120°C. The screw speed is set to 18 rpm. The thermocouple temperature at the extruder outlet is ensured to be within the range of 125 to 145°C. The thermocouple temperature is set to 135°C to obtain a rubber composition Q. (5) Rubber discharge stage: The rubber composition Q discharged from the mixing section extruder C is directly passed to the single screw extruder D in the rubber discharge section. The sleeve temperature is set to 115°C and controlled within the range of 100-120°C. The screw speed is set to 18 rpm. The silica-filled rubber composition is discharged from the equipment through the die, and the final rubber composition Q is obtained by stacking and collecting.

[0030] (6) Vulcanization stage: sulfur and an accelerator are added to the rubber composition Q according to the formula design using an internal mixer or an open mixer to obtain a rubber composition Q1.

[0031] No filler oil is added in the preparation process of Example 2.

[0032] In the preparation process of Example 3, the natural rubber is replaced by styrene-butadiene rubber, and no filler oil is added.

[0033] The preparation process of Comparative Example 1 is as follows: Use a 25L internal mixer, control the mixer rotor speed to 35rpm, and the mixer cooling water temperature to 35℃. The specific steps are as follows: (1) natural rubber, butadiene rubber, carbon black, white carbon black, silane coupling agent, filler oil, antioxidant TMQ, petroleum resin, zinc oxide, stearic acid, and microcrystalline wax are all added to an internal mixer, the top plug is pressed and the temperature is raised to 110° C., the top plug is pressed once, the temperature is raised to 140° C., the temperature is kept constant at 140-145° C. for 90 seconds, and then the rubber is discharged to obtain a rubber composition R; (2) The rubber composition R is re-mixed once in an internal mixer at a constant temperature of 140 to 145° C. for 60 seconds, and then the rubber is discharged; (3) After re-mixing, sulfur and accelerator were added to the rubber composition R, and the rubber removal temperature was 100°C to obtain the rubber composition R1.

[0034] In the preparation process of Comparative Example 2, no filler oil was added.

[0035] Test Method 1. Use Akron abrasion tester and DIN abrasion tester to test the wear performance and evaluate the wear resistance of the rubber composition; 2. Use DMA analyzer to test and evaluate the dynamic performance of the rubber composition, and characterize the heat generation performance and grip performance of the rubber composition; DMA test conditions: 7%±0.25%, 12HZ, -50℃~80℃, 2℃ / min; 3. Use Mooney viscometer to test the Mooney viscosity of the rubber composition and evaluate its processing performance; 4. Use RPA rheometer to test the Payne effect of the rubber composition and evaluate the dispersion of fillers in the rubber composition.

[0036] Comparative Example 1 is used as the data benchmark.

[0037] Table 2 By comparing Examples 1-3 and Comparative Examples 1-2, it can be seen that in the natural rubber or styrene-butadiene rubber / butadiene rubber system, compared with the traditional mixing method, the mixing method of the present invention is conducive to improving the wear resistance of the rubber composition, the aging retention rate of the wear performance, and the carbon black dispersion grade, and is conducive to reducing the Mooney viscosity and Payne effect. And under the premise of equal hardness, the removal of filler oil (reducing the amount of carbon black) can ensure the wear performance and processing performance, and reduce the heat generation performance (60°C tanδ) of the rubber composition.

[0038] The above is a description of the embodiments of the present invention. Through the above description of the disclosed embodiments, professionals and technicians in the field can implement or use the present invention. Various modifications to these embodiments will be apparent to professionals and technicians in the field. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown in this article, but will conform to the widest range consistent with the principles and novelties disclosed herein.

Claims

1. A mixing method for a high wear-resistant and low heat generation rubber composition, It is characterized in that The following phases are included: Raw material mixing stage: rubber component 1 and rubber component 2 are mixed in different internal mixers respectively; The rubber component 1 is a mixture of butadiene rubber, 10% to 30% carbon black, white carbon black, silane coupling agent, activator, antioxidant and resin; the rubber component 2 is a mixture of natural rubber or styrene-butadiene rubber, 70% to 90% carbon black, or a mixture of natural rubber or styrene-butadiene rubber, 70% to 90% carbon black and filler oil; The rubber component 1 is mixed by an internal mixer M, and the mixture is heated to a set temperature and then discharged into an extruder A; the internal mixer M is set to a discharge temperature of 120 to 140° C., a set speed of 30 to 60 rpm, and a pressurization of 30 to 60 seconds; The rubber component 2 is mixed by an internal mixer N, and the mixture is heated to a set temperature and then discharged into an extruder E; the internal mixer N is set to have a discharge temperature of 150 to 160° C., a set speed of 30 to 60 rpm, and a pressurization of 30 to 60 seconds; Heating stage: a. Setting the screw speed and barrel temperature of extruder A, while mixing the rubber component 1, raising the mixing temperature, and transferring the rubber component 1 to extruder B; the speed of the extruder A is 10-50 rpm, the barrel temperature is 120-150° C., and the outlet thermocouple temperature is 130-140° C.; b. Set the screw speed and barrel temperature of the extruder E to control the mixing temperature while mixing the rubber component 2; the speed of the extruder E is 10-50 rpm, the barrel temperature is 120-150° C., and the outlet thermocouple temperature of the extruder E is 150-170° C.; At the same time, a vacuum pump is used to extract the VOC gas inside the extruder A and the extruder E. The VOC gas extracted by the vacuum pump is effectively treated by the VOC recovery and treatment device; Constant temperature stage: the speed of extruder B is set to 100-200 rpm, the sleeve temperature is set to 100-150°C, the rubber component 1 is kept at a constant temperature in the extruder B, and a vacuum pump is used to extract the VOC gas inside the extruder B. The VOC gas extracted by the vacuum pump is effectively treated by the VOC recovery and treatment device; the rubber component 1 and the rubber component 2 after exhaust are transferred to the extruder C; Component mixing stage: the rubber component 1 and the rubber component 2 are finally mixed in the extruder C to obtain the rubber composition Q, the rotation speed of the extruder C is 15-20 rpm, the sleeve temperature is 110-120° C., and the outlet thermocouple temperature is 125-145° C.; Rubber discharge stage: set the speed of extruder D to 10-25 rpm and the sleeve temperature to 100-120°C, transfer the rubber composition Q in extruder C to extruder D, and finally extrude, sheet and collect the rubber composition Q through extruder D.

2. The mixing method according to claim 1, It is characterized in that The extruder A, extruder B, extruder C and extruder E are single-screw extruders or twin-screw extruders.

3. The mixing method according to claim 1, It is characterized in that The extruder A, extruder B, extruder C and extruder E are twin-screw extruders, and the length-to-diameter ratio of the twin screws is 25:1-40:

1.

4. The mixing method according to claim 1, It is characterized in that The rotation speed of the extruder A and the extruder E is 25-45 rpm; the sleeve temperature of the extruder A is 120-130°C, and the sleeve temperature of the extruder E is 130-150°C.

5. The mixing method according to claim 1, It is characterized in that The rotation speed of the extruder B is 100-150 rpm; the sleeve temperature of the extruder B is 110-125°C.

6. The mixing method according to claim 1, It is characterized in that The extruder D is a single screw extruder.

7. The mixing method according to claim 1, It is characterized in that The rotation speed of the extruder D is 15-20 rpm.

8. The mixing method according to claim 1, It is characterized in that The rubber composition 1 stays in the extruder B for no less than 90 seconds, and stays in the extruders A and B for no less than 120 seconds in total.

9. A high wear-resistant and low heat generation rubber composition prepared by the mixing method according to any one of claims 1 to 8.

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