Process for the preparation of a tire sidewall compound

Abstract

The application provides a preparation method of a tire sidewall rubber compound and belongs to the field of regenerated rubber compound production; green regenerated rubber is sent into a second double-screw extruder through a conveying device, a lignin composition is mixed and stirred to obtain material, the material is added into a mixing section of the extruder through a side feeding device, the temperature of the extruder is controlled to be 100 DEG C to 155 DEG C, and the material is reacted for 3 min to 5 min; the material is sent into a third single-screw extruder, the temperature of the screw extruder is controlled to be 70 DEG C to 85 DEG C, zinc oxide, stearic acid and an antioxidant are put into the extruder through a feeding device, the material is discharged after being mixed for 2 min to 4 min, sulfur and an accelerator are added into a first internal mixer, the material is mixed and stirred to be discharged at 80 DEG C to 100 DEG C, the material is sheeted on an open mill, and the material is cooled and stacked; the application uses biomass as a waste rubber regeneration aid to prepare green regenerated rubber, lignin partially replaces white carbon black to be used as a rubber reinforcing agent, and the prepared tire sidewall rubber compound is green, has little odor, has low required energy consumption and little environmental pollution.

Description

Technical Field

[0001] This invention relates to the technology of manufacturing recycled rubber compounds, and more particularly to a method for preparing tire sidewall rubber compounds, belonging to the field of recycled rubber manufacturing technology. Background Technology

[0002] With the development of society and the economy, a large amount of waste rubber has been generated, putting enormous pressure on resources and the environment. How to efficiently and greenly recycle waste rubber is one of the major challenges facing the polymer science and rubber industry. In the recycling process of waste rubber, a certain amount of activators and softeners are usually added. During the desulfurization and regeneration of waste rubber powder, the additives present in the rubber itself will produce various volatile organic compounds. The added desulfurization additives can also cause the prepared recycled rubber to have an unpleasant odor. Some of these gases are released during the production process, polluting the environment, while others remain in rubber products. On the one hand, this affects the overall performance of the rubber products; on the other hand, the gases are slowly released during the subsequent use of the rubber, not only affecting the user experience but also posing certain health risks.

[0003] As people pay more and more attention to health, the requirements for the odor level of car tires are also getting higher and higher, which has led to restrictions on the use of waste rubber in tires.

[0004] Chinese patent (202310850546.5 A Low-Odor, Low-Heat Outer Sheath Rubber Composition, Mixing Method, and Tire) discloses a low-odor, low-heat outer sheath rubber composition, mixing method, and tire. It uses a natural rubber composite material to completely or partially replace natural rubber. This natural rubber composite material includes an antibacterial agent that acts on microorganisms before they decompose the non-rubber components, rather than adsorbing or removing the odorous gases produced after the microorganisms have decomposed the non-rubber components. This fundamentally eliminates the deterioration, mold growth, and odor of natural rubber, avoiding the odorous gases produced by tires made from natural rubber. However, this method uses an antibacterial agent to reduce odor, involves many steps in the process, and requires a long time, which is not conducive to industrial production.

[0005] Chinese Patent (202010621769.0 A Method for Reducing the Odor of Pneumatic Tires and a Low-Odor Tire) discloses a method for reducing the odor of pneumatic tires and a low-odor tire, comprising providing a rubber mixing solution; the rubber mixing solution includes an organic solvent for dissolving the rubber and a rubber composition, the rubber composition comprising the following components in parts by weight: 60-100 parts butyl rubber; 0-40 parts natural rubber; 30-70 parts carbon black; 1-10 parts naphthenic oil; 2-6 parts zinc oxide; 1-3 parts stearic acid; 2-6 parts adhesive resin; 2-6 parts dispersant; 0.5-2 parts sulfur; applying the rubber mixing solution to the surface of an unvulcanized green tire, vulcanizing it, to obtain a low-odor tire. This method requires a large amount of organic solvent to dissolve the rubber composition, and the organic solvent will directly evaporate into the air, which is very environmentally unfriendly.

[0006] Therefore, there is an urgent need for a method to prepare tire sidewall rubber compounds that are green, environmentally friendly, have low odor, and low energy consumption. Summary of the Invention

[0007] This invention provides a novel method for preparing tire sidewall rubber compound, which uses biomass as a waste rubber recycling agent and lignin as a rubber reinforcing agent to solve the technical problems of complex tire production processes and strong odor in the prior art.

[0008] The method for preparing tire sidewall rubber compound according to an embodiment of the present invention includes the following steps:

[0009] Step 1: Preparation of green reclaimed rubber; Waste rubber powder, biomass A, and biomass B are put into a mixing device in a certain mass ratio and stirred for 4-7 minutes. When the material temperature reaches 110-130℃, the material is discharged and sent to the first twin-screw extruder through a conveying device. The temperature of the screw extruder is controlled at 130℃-155℃ and the reaction is carried out for 2-4 minutes to prepare green reclaimed rubber.

[0010] Step 2: Preparation of lignin composition; natural rubber, butadiene rubber, softener, lignin, silica, and silane coupling agent are added to a mixing device and stirred for 1-3 minutes. When the temperature of the rubber compound reaches 100℃-120℃, the material is discharged.

[0011] Step 3: Preparation of tire sidewall compound; The compound prepared in Step 1 is fed into the second twin-screw extruder via a conveying device. The material obtained from the mixing in Step 2 is added to the mixing section of the extruder via a side feeding device. The temperature of the extruder is controlled at 100℃-155℃, and the reaction is carried out for 3-5 minutes. The material is then fed into the third single-screw extruder, and the temperature of the screw extruder is controlled at 70℃-85℃. Zinc oxide, stearic acid, and antioxidant are added to the extruder via a feeding device. After mixing for 2-4 minutes, the material is discharged and fed into the first internal mixer. Sulfur and accelerator are added and the mixture is mixed until it reaches 80-100℃ before being discharged. The material is then sheeted from the open mill to obtain the tire sidewall compound.

[0012] In the first step, the mass ratio of waste rubber powder, biomass A, and biomass B is 100:3-10:4-8; the waste rubber powder is any one or more mixtures of waste tire tread rubber powder and waste tire tire rubber powder, and the mesh size of the waste rubber powder is 20-80 mesh; biomass A is a plant regeneration agent, including any one or more combinations of garlic juice and lemon peel juice; biomass B is any one or more combinations of soybean oil, castor oil, rapeseed oil, and palm oil.

[0013] In the tire sidewall compound preparation method described above, the length-to-diameter ratio of the screw of the first twin-screw extruder in the first step is 24-32:1.

[0014] In the tire sidewall compound preparation method described above, in the third step, the mixing section temperature of the second twin-screw extruder is 110℃-125℃, the reaction section temperature is 145℃-155℃, the cooling section temperature is 110℃-120℃, and the length-to-diameter ratio of the screw is 32-42:1.

[0015] In the tire sidewall compound preparation method described above, in the third step, the length-to-diameter ratio of the screw of the third single-screw extruder is 28-36:1.

[0016] In the tire sidewall compound preparation method described above, in step three, the rotor speed of the first internal mixer is 50-90 r / min, the filling coefficient is 0.3-0.7, the mixing time is 50-90 s, and the top bolt pressure is 5-8 kg / cm². 2 .

[0017] The tire sidewall compound preparation method described above, wherein the compound comprises the following raw material components in parts by weight:

[0018] Natural rubber 25-45 parts, butadiene rubber 20-40 parts, green reclaimed rubber 8-16 parts, softener 8-15 parts, lignin 8-18 parts, silica 20-35 parts, silane coupling agent 8-13 parts, zinc oxide 2-5 parts, stearic acid 1-3 parts, antioxidant 0-3 parts, accelerator 2-5 parts, sulfur 2-4 parts.

[0019] The tire sidewall compound preparation method described above includes the following: the softener is any one or a combination of aromatic oil, naphthenic oil, and tall oil; the lignin is any one or a combination of sulfate lignin, lignin sulfonate, alkali lignin, and organic solvent lignin; the silane coupling agent is any one of KH580, KH550, and Si-69; the antioxidant is any one of antioxidant 4010, antioxidant 4010NA, and antioxidant 4020; and the accelerator is any one of accelerator D, accelerator DM, accelerator TMTD, and accelerator CZ.

[0020] In this invention, vegetable oil is added to waste rubber powder as a regeneration aid to obtain reclaimed rubber with a high degree of regeneration. Due to the chemical structure of vegetable oil, which has long and flexible higher fatty acid chains, it can more easily penetrate into the three-dimensional cross-linked network of the rubber powder during the regeneration process, causing the rubber powder to swell sufficiently. Simultaneously, it helps the rubber regenerator disperse into the cross-linked network of the rubber powder, resulting in reclaimed rubber with excellent desulfurization under conditions such as mechanical shearing. Using garlic juice or lemon peel juice, a room-temperature rubber regenerator that can chemically replace and break down sulfur cross-links in vulcanized rubber, can limit the damage of oxidation to the rubber molecular backbone. It can also be mechanically processed at room temperature to give the rubber compound plasticity while maintaining good physical properties. This ensures that the prepared green reclaimed rubber, when used in tire sidewall compounds, meets its mechanical performance requirements without producing harmful gases such as hydrogen sulfide, reducing odor generation and environmental pollution. Replacing silica with lignin can not only improve the reinforcing properties of the rubber compound and reduce the amount of silica used, but also has a certain anti-aging effect, which can reduce the use of antioxidants in the rubber compound.

[0021] This invention utilizes a softener that is liquid at room temperature, eliminating the need for additional heating devices to mix with the rubber powder. The rubber compound enters a mixing device, where high-speed rotation generates heat through self-friction between rubber particles and between the rubber powder and the mixing device, thus raising the material's temperature and allowing for initial de-crosslinking of the waste rubber powder. When the pre-de-crosslinked material enters the screw extruder, high heating temperatures and a large screw length-to-diameter ratio are not required; the strong shearing action of the screw achieves final desulfurization, resulting in low overall energy consumption. Furthermore, the preparation of the lignin composition and the green reclaimed rubber are carried out simultaneously. After the green reclaimed rubber is prepared, it enters the second twin-screw extruder without cooling, where it is mixed with the lignin composition and undergoes a silanization reaction, improving preparation efficiency and reducing energy consumption. When the material enters the third single-screw extruder, it is cooled while zinc oxide, stearic acid, antioxidants, and other additives are added and mixed to prepare for vulcanization.

[0022] The green reclaimed rubber of this invention does not use chemical additives in its preparation process and operates at a low regeneration temperature, effectively reducing the generation of odor and not affecting its use in tire sidewall compounds. The addition of green reclaimed rubber to the tire sidewall compound formulation reduces the amount of natural rubber and butadiene rubber used, thereby reducing the impact of odor from amine derivatives and fatty acids produced by protein decomposition in natural rubber, as well as residual organic solvents and catalysts used in the synthesis of synthetic rubber. Detailed Implementation

[0023] The method for preparing tire sidewall rubber compound according to the present invention can be made using the following materials and components, but is not limited to the following materials and components, such as: waste rubber powder, garlic juice, soybean oil, natural rubber, etc.

[0024] The specific embodiments of the preparation method of tire sidewall rubber material of the present invention are as follows.

[0025] Example 1

[0026] Step 1: Add waste rubber powder, garlic juice, and soybean oil to a mixing device in a mass ratio of 100:4:6 and mix for 4 minutes. When the material temperature reaches 115℃, discharge the material and send it to the first twin-screw extruder via a conveying device. The screw length-to-diameter ratio is 24:1. Control the screw extruder temperature at 136℃ and react for 2 minutes to prepare green recycled rubber.

[0027] Step 2: Add 25 parts natural rubber, 30 parts butadiene rubber, 10 parts naphthenic oil, 8 parts sulfate lignin, 20 parts silica, and 8 parts silane coupling agent KH580 into a mixing device and stir for 2 minutes. Discharge the material when the temperature of the rubber compound reaches 109°C.

[0028] Step 3: Ten parts of the rubber compound prepared in Step 1 are fed into the second twin-screw extruder via a conveying device. The length-to-diameter ratio of the screws is 36:1. The material obtained from the mixing in Step 2 is added to the mixing section of the extruder via a side feeding device. The temperature of the mixing section is 115℃, the temperature of the reaction section is 148℃, and the temperature of the cooling section is 120℃. The reaction is carried out for 3 minutes. The material is then fed into the third single-screw extruder. The length-to-diameter ratio of the screw in the third single-screw extruder is 28:1. The temperature of the screw extruder is controlled at 70℃. Two parts of zinc oxide, one part of stearic acid, and one part of antioxidant 4010 are added to the extruder via a feeding device. After mixing for 2 minutes, the material is discharged and sent to the first internal mixer. Two parts of sulfur and three parts of accelerator D are added and mixed until the temperature reaches 87℃ before being discharged. The material is then sheeted from the open mill, cooled, and stacked.

[0029] When the preliminarily decrosslinked material enters the third screw extruder, it does not require high heating temperature and a large screw length-to-diameter ratio. By utilizing the strong shearing action of the screw, the decrosslinking of rubber molecular chains can be achieved under low temperature conditions, resulting in less breakage of the rubber main chain, lower overall energy consumption, and good mechanical properties of the reclaimed rubber.

[0030] Example 2

[0031] Step 1: Add waste rubber powder, garlic juice, and rapeseed oil to a mixing device at a mass ratio of 100:4:5 and mix for 4 minutes. When the material temperature reaches 120℃, discharge the material and send it to the first twin-screw extruder via a conveying device. The screw length-to-diameter ratio is 28:1. Control the screw extruder temperature at 142℃ and react for 2 minutes to prepare green recycled rubber.

[0032] Step 2: Add 28 parts natural rubber, 32 parts butadiene rubber, 12 parts naphthenic oil, 10 parts sulfate lignin, 23 parts silica, and 10 parts silane coupling agent KH580 into a mixing device and stir for 2 minutes. Discharge the material when the temperature of the rubber compound reaches 118°C.

[0033] Step 3: 15 parts of the rubber compound prepared in Step 1 are fed into the second twin-screw extruder via a conveying device. The length-to-diameter ratio of the screws is 36:1. The material obtained from the mixing in Step 2 is added to the mixing section of the extruder via a side feeding device. The temperature of the mixing section is 120℃, the temperature of the reaction section is 150℃, and the temperature of the cooling section is 116℃. The reaction is carried out for 3 minutes. The material is then fed into the third single-screw extruder. The length-to-diameter ratio of the screw is 28:1. The temperature of the screw extruder is controlled at 73℃. 2 parts of zinc oxide, 1 part of stearic acid, and 1 part of antioxidant 4020 are added to the extruder via a feeding device. After mixing for 2 minutes, the material is discharged and sent to the first internal mixer. 2 parts of sulfur and 3 parts of accelerator CZ are added and mixed until the temperature reaches 82℃ before being discharged. The material is then sheeted from the open mill, cooled, and stacked.

[0034] Example 3

[0035] Step 1: Add waste rubber powder, lemon peel juice, and rapeseed oil to a mixing device at a mass ratio of 100:6:8 and mix for 5 minutes. When the material temperature reaches 124℃, discharge the material and send it to the first twin-screw extruder via a conveying device. The screw length-to-diameter ratio is 28:1. Control the screw extruder temperature at 148℃ and react for 3 minutes to prepare green recycled rubber.

[0036] Step 2: Add 33 parts natural rubber, 26 parts butadiene rubber, 10 parts aromatic oil, 11 parts alkali lignin, 25 parts silica, and 11 parts silane coupling agent KH550 into the mixing device and stir for 2 minutes. Discharge the material when the temperature of the rubber compound reaches 116℃.

[0037] Step 3: 16 parts of the rubber compound prepared in Step 1 are fed into the second twin-screw extruder via a conveying device. The length-to-diameter ratio of the screws is 36:1. The material obtained from the mixing in Step 2 is added to the mixing section of the extruder via a side feeding device. The temperature of the mixing section is 122℃, the temperature of the reaction section is 148℃, and the temperature of the cooling section is 112℃. The reaction is carried out for 3 minutes. The material is then fed into the third single-screw extruder. The length-to-diameter ratio of the screw is 32:1. The temperature of the screw extruder is controlled at 70℃. 2 parts of zinc oxide, 1 part of stearic acid, and 1 part of antioxidant 4020 are added to the extruder via a feeding device. After mixing for 2 minutes, the material is discharged and sent to the first internal mixer. 2 parts of sulfur and 3 parts of accelerator CZ are added and mixed until the temperature reaches 82℃ before being discharged. The material is then sheeted from the open mill, cooled, and stacked.

[0038] The performance test results of the above embodiments are shown in Table 1.

[0039] Table 1 Results of Rubber Compound Performance Tests

[0040] Test Project Example 1 Example 2 Example 3 300% constant tensile stress / MPa 7.4 7.6 7.7 Tensile strength / MPa 18.8 18.9 19.2 Elongation at break / % 676 678 681 Hardness / Shore A 54 55 57 Tear strength (N / mm) 133 135 136 400,000 flexural cracks No cracks No cracks No cracks

[0041] As can be seen from the table above, the formulations of Examples 1, 2, and 3 can meet the requirements of tire sidewall rubber compounds.

[0042] The sequence numbers of the above embodiments of the present invention are merely for descriptive purposes and do not represent the superiority or inferiority of the embodiments. Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of some modifications and the superposition of necessary general technologies; of course, they can also be implemented by simplifying some important technical features. Based on this understanding, the technical solution of the present invention, in essence or the part that contributes to the prior art, is: the overall structure and connection method, and the structure described in the various embodiments of the present invention.

[0043] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a tire sidewall rubber compound, characterized in that, Includes the following steps: Step 1: Preparation of green reclaimed rubber; Waste rubber powder, biomass A, and biomass B are put into a mixing device in a certain mass ratio and stirred for 4-7 minutes. When the material temperature reaches 110-130℃, the material is discharged and sent to the first twin-screw extruder through a conveying device. The temperature of the screw extruder is controlled at 130℃-155℃ and the reaction is carried out for 2-4 minutes to prepare green reclaimed rubber. Step 2: Preparation of lignin composition; natural rubber, butadiene rubber, softener, lignin, silica, and silane coupling agent are added to a mixing device and stirred for 1-3 minutes. When the temperature of the rubber compound reaches 100℃-120℃, the material is discharged. Step 3: Preparation of tire sidewall compound; The compound prepared in Step 1 is fed into the second twin-screw extruder via a conveying device. The material obtained from the mixing in Step 2 is added to the mixing section of the extruder via a side feeding device. The temperature of the extruder is controlled at 100℃-155℃, and the reaction is carried out for 3-5 minutes. The material is then fed into the third single-screw extruder, and the temperature of the screw extruder is controlled at 70℃-85℃. Zinc oxide, stearic acid, and antioxidant are added to the extruder via a feeding device. After mixing for 2-4 minutes, the material is discharged and fed into the first internal mixer. Sulfur and accelerator are added and the mixture is mixed until it reaches 80-100℃ before being discharged. The material is then sheeted from the open mill to obtain the tire sidewall compound. In the first step, the mass ratio of waste rubber powder, biomass A, and biomass B is 100:3-10:4-8; the waste rubber powder is any one or more mixtures of waste tire tread rubber powder and waste tire tire rubber powder, and the mesh size of the waste rubber powder is 20-80 mesh; biomass A is a plant regeneration agent, including any one or more combinations of garlic juice and lemon peel juice; biomass B is any one or more combinations of soybean oil, castor oil, rapeseed oil, and palm oil.

2. The method for preparing tire sidewall rubber compound according to claim 1, characterized in that, In the first step, the length-to-diameter ratio of the screw of the first twin-screw extruder is 24-32:

1.

3. The method for preparing tire sidewall rubber compound according to claim 1, characterized in that, In the third step, the mixing section temperature of the second twin-screw extruder is 110℃-125℃, the reaction section temperature is 145℃-155℃, the cooling section temperature is 110℃-120℃, and the length-to-diameter ratio of the screw is 32-42:

1.

4. The method for preparing tire sidewall rubber compound according to claim 1, characterized in that, In the third step, the length-to-diameter ratio of the screw of the third single-screw extruder is 28-36:

1.

5. The method for preparing tire sidewall rubber compound according to claim 1, characterized in that, In step three, the rotor speed of the first internal mixer is 50-90 r / min, the filling coefficient is 0.3-0.7, the mixing time is 50-90 s, and the top bolt pressure is 5-8 kg / cm². 2 .

6. The method for preparing tire sidewall rubber compound according to claim 1, characterized in that, This rubber compound comprises the following raw material components in parts by weight: Natural rubber 25-45 parts, butadiene rubber 20-40 parts, green reclaimed rubber 8-16 parts, softener 8-15 parts, lignin 8-18 parts, silica 20-35 parts, silane coupling agent 8-13 parts, zinc oxide 2-5 parts, stearic acid 1-3 parts, antioxidant 0-3 parts, accelerator 2-5 parts, sulfur 2-4 parts.

7. The method for preparing tire sidewall rubber compound according to claim 1, characterized in that, The softener is any one or a combination of aromatic oil, cycloalkanes oil, and tall oil; the lignin is any one or a combination of sulfate lignin, lignin sulfonate, alkali lignin, and organic solvent lignin; the silane coupling agent is any one of KH580, KH550, and Si-69; the antioxidant is any one of antioxidant 4010, antioxidant 4010NA, and antioxidant 4020; and the accelerator is any one of accelerator D, accelerator DM, accelerator TMTD, and accelerator CZ.