A sidewall rubber composition with reduced carbon black use and method of making the same, tire

Abstract

This invention relates to the field of tire rubber manufacturing technology, and discloses a sidewall rubber composition that reduces carbon black usage, its preparation method, and a tire. The sidewall rubber composition of this invention is applied to economical semi-steel radial tires. Through the reinforcing substitution of reclaimed rubber, carbon black, and inorganic materials, and by redesigning and optimizing the formulation, the use of carbon black is significantly reduced. For example, by adding pyrolysis carbon black, silica, and ultrafine diatomaceous earth, the furnace black, pyrolysis carbon black, silica, and ultrafine diatomaceous earth work synergistically. Furthermore, by adjusting the proportions of natural rubber, butadiene rubber, sulfur, accelerators, and other components, the goal of reducing carbon dioxide emissions while meeting tire performance requirements can be achieved.

Description

Technical Field

[0001] This invention relates to the field of tire rubber manufacturing technology, and more specifically, to a sidewall rubber composition that reduces carbon black usage, its preparation method, and a tire. Background Technology

[0002] Carbon black has been used in rubber tire reinforcement materials for 130 years. In 2022, global carbon black production reached 14 million tons, with 75% used in tire manufacturing, demonstrating its indispensable role in tire production. While the use of silica (white carbon black) in tire treads has seen rapid growth in recent years due to patents from various companies, carbon black still remains the dominant material in rubber tire reinforcement. Approximately 80% of this is produced using the furnace black process, which involves the incomplete combustion of feedstock oil and fuel oil in an oil furnace. Furnace black is the primary reinforcing filler material for rubber tires due to its excellent oleophilicity and suitable agglomerate morphology distribution, which complements the reinforcing properties of rubber materials.

[0003] Since Michelin published its "green tire" patent in 1992, which used a high proportion of silica in tire tread compounds, the use of silica in the tire industry has indeed developed significantly, reducing the proportion of carbon black used to some extent. However, silica is mainly used in high-performance tires such as high wet grip (HPT) tires or low rolling resistance tire tread compounds. In economy car tires, long mileage, impact resistance, and reasonable pricing are more prevalent. Economy tires require a tread wear index of at least half UTGQ 500, so a "semi-green" formula using pure carbon black or half silica is more suitable. Occasionally, silica is used to replace part of the carbon black in components other than the tread compound, such as the carcass and base compound: for example, patent CN201410609368.8 for carcass compounds using wet mixing, and patents CN201210281772.8 and CN200810155766.1 for all-steel base compounds using silica. Patent CN201310268279.7, among others, describes the use of diatomaceous earth as a substitute for carbon black in the airtight layer. It can be seen that the use of silica in the carcass rubber employs a special mixing method, while its use in the base rubber is mainly concentrated in all-steel tires. The use of diatomaceous earth in the inner liner is somewhat more mature. Statistically, carbon black currently accounts for 27% of the mass of the rubber compound in economical semi-steel radial tire formulations.

[0004] From an environmental perspective, it is known that the oil furnace combustion process emits approximately 1.8 tons of carbon dioxide per ton of carbon black. Furthermore, the entire process from crude oil production to carbon black packaging generates as much as 4.5 tons of carbon dioxide per ton of carbon black produced. Therefore, carbon black is a high-carbon dioxide emission product. Reducing the use of furnace-processed carbon black is therefore crucial for reducing carbon dioxide emissions. Consequently, the production of economy cars necessitates a significant reduction in carbon black usage to substantially decrease carbon dioxide emissions. Summary of the Invention

[0005] This invention addresses the shortcomings of existing technologies by providing a sidewall rubber composition that reduces carbon black usage, its preparation method, and a tire. The sidewall rubber composition provided by this invention can achieve tire performance while reducing carbon dioxide emissions.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A tire sidewall rubber composition for reducing carbon black usage, said rubber composition is prepared by mixing raw materials comprising the following components based on 100 parts by weight of raw rubber:

[0008] 40-60 parts of natural rubber

[0009] 40-60 parts of butadiene rubber

[0010] 25-35 parts furnace black

[0011] 15-25 parts of pyrolysis carbon black

[0012] 5-15 parts of silica

[0013] 5-15 parts of ultrafine diatomaceous earth

[0014] 5-15 parts of environmentally friendly oil

[0015] 1-4 parts zinc oxide

[0016] 1-2 parts stearic acid

[0017] 2-5 parts of p-phenylenediamine antioxidant

[0018] 1-3 parts of TMQ anti-aging agent

[0019] 1-2.5 parts microcrystalline wax

[0020] 1-3 parts sulfur powder

[0021] Accelerator 0.5-2 parts.

[0022] Preferably, the rubber composition is prepared by mixing raw materials comprising the following components based on 100 parts by weight of raw rubber:

[0023] 45-55 parts natural rubber

[0024] 45-55 parts of butadiene rubber

[0025] 25-30 parts furnace black

[0026] 15-20 parts of pyrolysis carbon black

[0027] 8-12 parts of silica

[0028] 5-10 parts of ultrafine diatomaceous earth

[0029] 8-12 parts of environmentally friendly oil

[0030] 2-3 parts zinc oxide

[0031] 1-2 parts stearic acid

[0032] 2.5-3 parts of p-phenylenediamine antioxidant

[0033] 1-2 parts of TMQ anti-aging agent

[0034] 1-2 parts of microcrystalline wax

[0035] 1-2 parts sulfur powder

[0036] Accelerator 0.5-1 part.

[0037] The sidewall compound is a rubber composition that protects the outermost layer of the tire's skeleton material (polyester layer) from scratches by external objects. It needs to ensure sufficient flexural strength and resistance to aging and cracking during use, while also maintaining tear resistance, to protect the tire carcass. The raw rubber system uses a blend of natural rubber and butadiene rubber. Sufficient butadiene rubber is required because it has excellent flexural and fatigue resistance; therefore, it is generally used at least 40 parts. Natural rubber (NR) has a high molecular weight and good tear resistance, thus providing scratch resistance. When using pyrolysis carbon black, silica, or ultrafine diatomaceous earth instead of carbon black, the proportion of non-carbon black components needs to be carefully controlled to ensure flexural strength. The sidewall compound hardness is designed to be 54-58, the 300% elongation design is 4-6 MPa, and the minimum elongation is 500%. High elongation is beneficial for improving flexural strength. The antioxidant system for tire sidewall rubber is crucial. It typically uses a combination of p-phenylenediamine antioxidants 4020, TMQ, and microcrystalline wax. Excessive microcrystalline wax can cause appearance problems during storage due to waxing, while insufficient wax can lead to ozone cracking. The optimal ratio of accelerator to sulfur should be less than 1:2, i.e., a high-sulfur, low-accelerator system. In this system, the sulfur bonds are predominantly long-chain, resulting in good rubber flexural strength.

[0038] Preferably, the BET specific surface area of ​​the silica is 85-120 m². 2 / g or 150-170m 2 / g, the former is represented by Solvay 1115MP, and the latter is represented by Solvay 1165MP; the furnace black is a high-reinforcing series carbon black or a fast-extrusion series carbon black, including but not limited to N220, N234, N330, N326, N375, and N550.

[0039] Preferably, the proportion of furnace black, pyrolysis black, silica, and ultrafine diatomite in the total proportion of furnace black, pyrolysis black, silica, and ultrafine diatomite is not less than 40%.

[0040] Preferably, the ultrafine diatomite is a layered filler with an average layer diameter of <500nm, a thickness of <100nm, and a median particle size D50 ≤10μm; the ultrafine diatomite is obtained by water milling.

[0041] Preferably, the sulfur powder is at least twice the amount of the accelerator.

[0042] Preferably, the accelerator is a sulfenamide accelerator, preferably accelerator NS or accelerator CZ.

[0043] Furthermore, the present invention also discloses a method for preparing the rubber composition, comprising the following steps:

[0044] 1) First stage mixing: Using a tangential internal mixer, add raw rubber and plasticize for 20-50 seconds, then add carbon black, silica, ultrafine diatomaceous earth, environmentally friendly oil, zinc oxide, stearic acid, antioxidant and microcrystalline wax, pressurize to 120-130℃, remove the roller to clean, then pressurize to 150-165℃ to discharge the rubber, and let the obtained masterbatch stand for 4-8 hours;

[0045] 2) Final mixing: Using a tangential internal mixer, add masterbatch, sulfur and accelerator, mix under pressure for 20-35 seconds, remove the roller to clean, and pressurize to 100-110℃ to discharge the rubber composition.

[0046] Furthermore, the present invention also discloses a tire in which the sidewall rubber is prepared by vulcanization of the aforementioned rubber composition.

[0047] The beneficial effects of this invention are as follows: When the sidewall rubber composition of this invention is applied to an economical semi-steel radial tire, the use of carbon black is significantly reduced through the reinforcing substitution of reclaimed rubber, carbon black, and inorganic materials, as well as the redesign and optimization of the formula. For example, by adding pyrolysis carbon black, silica, and ultrafine diatomaceous earth, furnace black, pyrolysis carbon black, silica, and ultrafine diatomaceous earth work synergistically. Furthermore, by adjusting the proportions of natural rubber, butadiene rubber, sulfur, accelerators, and other components, the goal of reducing carbon dioxide emissions can be achieved while meeting tire performance requirements. Detailed Implementation

[0048] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present invention.

[0049] Example

[0050] A tire sidewall rubber composition that reduces carbon black usage is provided, the formulation of which is shown in Table 1. The sulfur powder contains 10% oil, and the furnace black 2 is a high-structure, high-abrasion-resistant carbon black.

[0051] The preparation method of the rubber composition is as follows:

[0052] 1) First stage mixing: Using a tangential internal mixer, add raw rubber and plasticize for 20-50 seconds, then add carbon black, silica, ultrafine diatomaceous earth, environmentally friendly oil, zinc oxide, stearic acid, antioxidant and microcrystalline wax, pressurize to 120-130℃, remove the roller to clean, then pressurize to 150-165℃ to discharge the rubber, and let the obtained masterbatch stand for 4-8 hours;

[0053] 2) Final mixing: Using a tangential internal mixer, add masterbatch, sulfur and accelerator, mix under pressure for 20-35 seconds, remove the roller to clean, pressurize to 100-110℃ to discharge the rubber composition, which can be used after standing for more than 4 hours.

[0054] Comparative Example

[0055] A sidewall rubber composition is provided, the formulation of which is shown in Table 1.

[0056] The preparation method of the rubber composition is as described in the examples.

[0057] Parameter

[0058] A tire sidewall rubber composition is provided, the formulation of which is shown in Table 1. The furnace black 4 is a fast-pressing furnace black.

[0059] The preparation method of the rubber composition is as described in the examples.

[0060] Table 1

[0061]

[0062]

[0063] Anti-aging cracking: 20% elongation, 50pphm ozone aging, 40℃; no cracking required after 72 hours.

[0064] Fatigue resistance (flexural fatigue): Requires no cracking after 500,000 cycles.

[0065] Table 1 footnotes:

[0066] 1. Natural rubber, Thai 20# standard rubber STR20, initial plasticity P0≥30, plasticity retention rate (PRI)≥40, Mooney viscosity ML(1+4) 100℃ 83;

[0067] 2. Butadiene rubber, nickel-based solution polymerized high cis-butadiene rubber, product model BR9000;

[0068] 3. Furnace black 1, N550, iodine absorption value 43g / kg, oil absorption value 121×10 5 m 3 / kg, CTAB adsorption specific surface area 85×10 3 m 2 / kg;

[0069] 4. Furnace black 2, N375, iodine absorption value 93g / kg, oil absorption value 114×10 5 m 3 / kg, CTAB adsorption specific surface area 96×10 3 m 2 / kg;

[0070] 5. Pyrolysis carbon black, DBP oil absorption value 85×10 5 m 3 / kg, Zhongce Qingquan Industrial Co., Ltd.;

[0071] 6. Silica, 1165 MPa, BET specific surface area 150-170 m² 2 / g, Solvay Chemicals products;

[0072] 7. Ultrafine diatomaceous earth, average sheet diameter <500nm, thickness <100nm, water-milled, Qixiang High-tech Materials Co., Ltd.

[0073] 8. p-Phenylenediamine antioxidant, antioxidant 6PPD, chemical name N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, ozone-resistant antioxidant, Sheng'ao Chemical Technology Co., Ltd.;

[0074] All other raw materials are conventional industrial products available on the market.

[0075] Referring to Table 1, the examples and comparative examples show that the synergistic effect of furnace black 2, pyrolysis black, silica, and ultrafine diatomaceous earth can replace furnace black 1 and reduce the amount of furnace black added, without affecting the performance of the rubber composition. Examples 1 and Comparative Examples 1-7 show that the absence of furnace black 2, pyrolysis black, silica, or ultrafine diatomaceous earth will affect the final replacement effect. Comparative Examples 8 and 9 adjusted the raw rubber ratio and appropriately adjusted the filler ratio. Compared with Example 1, the proportion of furnace black in Comparative Examples 8 and 9 was also reduced, but the performance of the rubber composition was relatively poor, with significantly worse tear resistance and / or anti-aging cracking and / or fatigue resistance. This indicates that butadiene rubber should not be too little or too much. Therefore, by appropriately adding other fillers and adjusting the formulation, the amount of furnace black added can be reduced, thus reducing carbon dioxide emissions.

[0076] The foregoing description of embodiments of the present invention, through which those skilled in the art are able to implement or use the present invention, will be readily apparent to those skilled in the art. Various modifications to these embodiments will be readily apparent to those skilled in the art. The general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novelty disclosed herein.

Claims

1. A tire sidewall rubber composition that reduces carbon black usage, characterized in that, The rubber composition is prepared by mixing raw materials comprising the following components based on 100 parts by weight of raw rubber: 40-60 parts of natural rubber 40-60 parts of butadiene rubber 25-35 parts furnace black 15-25 parts of pyrolysis carbon black 5-15 parts of silica 5-15 parts of ultrafine diatomaceous earth 5-15 parts of environmentally friendly oil 1-4 parts zinc oxide 1-2 parts stearic acid 2-5 parts of p-phenylenediamine antioxidant 1-3 parts TMQ anti-aging agent 1-2.5 parts microcrystalline wax 1-3 parts sulfur powder Accelerator 0.5-2 parts; Of the total proportions of furnace black, pyrolysis black, silica, and ultrafine diatomite, furnace black accounts for no less than 40%; the ultrafine diatomite is a layered filler with an average layer diameter <500nm, a thickness <100nm, and a median particle size D50 ≤10μm; the ultrafine diatomite is obtained by water milling.

2. The rubber composition according to claim 1, characterized in that, The rubber composition is prepared by mixing raw materials comprising the following components based on 100 parts by weight of raw rubber: 45-55 parts natural rubber 45-55 parts of butadiene rubber 25-30 parts furnace black 15-20 parts of pyrolysis carbon black 8-12 parts of silica 5-10 parts of ultrafine diatomaceous earth 8-12 parts of environmentally friendly oil 2-3 parts zinc oxide 1-2 parts stearic acid 2.5-3 parts of p-phenylenediamine antioxidant 1-2 parts TMQ anti-aging agent 1-2 parts of microcrystalline wax 1-2 parts sulfur powder Accelerator 0.5-1 part.

3. The rubber composition according to claim 1 or 2, characterized in that, The BET specific surface area of ​​the silica is 85-120m². 2 / g or 150-170m 2 / g; The furnace black is either a high-reinforcing series carbon black or a fast-extrusion series carbon black.

4. The rubber composition according to claim 3, characterized in that, The furnace black is N220, N234, N330, N326, N375 or N550.

5. The rubber composition according to claim 1 or 2, characterized in that, The sulfur powder is at least twice the amount of the accelerator.

6. The rubber composition according to claim 1 or 2, characterized in that, The accelerator is a sulfenamide accelerator.

7. The rubber composition according to claim 1 or 2, characterized in that, The accelerator is accelerator NS or accelerator CZ.

8. The method for preparing the rubber composition according to any one of claims 1-7, characterized in that, Includes the following steps: 1) First stage mixing: Using a tangential internal mixer, add raw rubber and plasticize for 20-50 seconds, then add carbon black, silica, ultrafine diatomaceous earth, environmentally friendly oil, zinc oxide, stearic acid, antioxidant and microcrystalline wax, pressurize to 120-130℃, remove the roller to clean, then pressurize to 150-165℃ to discharge the rubber, and let the obtained masterbatch stand for 4-8 hours; 2) Final mixing: Using a tangential internal mixer, add masterbatch, sulfur and accelerator, mix under pressure for 20-35 seconds, remove the roller to clean, and discharge the rubber at 100-110℃ to obtain the rubber composition.

9. A tire, characterized in that, The sidewall rubber of the tire is prepared by vulcanization of the rubber composition according to any one of claims 1-7.

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