Rubber composition for tire tread and preparation method thereof

Abstract

The invention discloses a rubber composition for tire tread rubber and a preparation method thereof, and belongs to the technical field of rubber. According to the product, the cis-butadiene-isoprene rubber and the natural rubber are compounded to serve as a rubber matrix, and meanwhile, specific types of carbon black and rubber oil are introduced to serve as compounding components, so that good using performance in a low-temperature environment can be achieved, and the product is high in elasticity, good in road holding force and good in cutting resistance.

Description

Technical Field

[0001] The invention relates to the field of rubber technology, and in particular to a rubber composition for tire tread and a preparation method thereof. Background Art

[0002] All-steel radial engineering machinery tires are used in mines, construction sites, etc., and they bear high loads and work for long hours. Therefore, they have high requirements for the tire tread rubber, such as cut resistance, wear resistance, and low heat generation. At present, the main materials used for tire tread rubber are natural rubber, styrene-butadiene rubber, and trans-butadiene-pentadiene rubber. However, the glass transition temperature of this type of rubber is generally high (generally Tg < -50°C). Therefore, when this type of product is used in cold areas, the tread may freeze and crack, and the performance will be greatly deteriorated or even fail.

[0003] To this end, people have tried to use high-cis polybutadiene rubber, which has better cold resistance among rubbers, in combination with natural rubber to prepare tread rubber for use in severe cold environments. However, high-cis polybutadiene rubber will crystallize and its molecular chains will freeze at -30°C, and the elasticity of the product will decrease significantly. The grip of the tire tread rubber will deteriorate, and it may even easily cause the vehicle to lose control. Summary of the invention

[0004] Based on the defects of the prior art, the purpose of the present invention is to provide a rubber composition, which can achieve good performance in low temperature environment, high elasticity, good grip and good cut resistance by compounding cis-butylene rubber and natural rubber as the rubber matrix, and introducing specific types of carbon black and rubber oil as compounding ingredients.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] A rubber composition comprising the following raw materials in parts by weight:

[0007] 40-60 parts of cis-butylene rubber, 40-60 parts of natural rubber, 45-60 parts of carbon black, 1-5 parts of rubber oil;

[0008] The glass transition temperature of the cis-butylene-pentadiene rubber is -90 to -82°C;

[0009] The carbon black has an iodine absorption value of 115 to 165 g / kg and a DBP oil absorption value of 105 to 140×10 -5 m 3 / kg;

[0010] The kinematic viscosity of the rubber oil at 40°C is ≤40 mm 2 / s, pour point ≤-24℃.

[0011] In order to ensure that the product has ideal cold resistance after being prepared into tire tread rubber, the rubber composition of the present invention is excellent in cold resistance and has a low glass transition temperature. The cis-butyl-pentyl rubber is matched with natural rubber in a specific ratio, taking into account the basic use performance of the product and the performance retention rate in a severe cold environment. At the same time, the amount of cis-butyl-pentyl rubber added should not be too much, otherwise the cutting resistance of the product will deteriorate. At the same time, the inventor found that under the rubber matrix, different types of carbon black have different bonding strengths and bonding effects with the rubber molecular chain. If improperly selected, it may cause the impact resistance and tear resistance of the product to decrease, cracks to appear in the rubber, and the dynamic cutting resistance to be significantly reduced. At the same time, it will also affect the cold resistance of the product. Therefore, it is necessary to select carbon black with specific iodine absorption value and oil absorption value as a compound filler under a suitable ratio; in addition, the viscosity and pour point of the rubber oil in the product also affect the low-temperature performance of the rubber matrix. Selecting rubber oil with low kinematic viscosity and low pour point for compounding can significantly improve the cold resistance of the product.

[0012] Preferably, the glass transition temperature Tg of the cis-1,4-butadiene-isoprene rubber (cis-1,4-butadiene-isoprene copolymer) under DMA test is in the range of one or any two of -90°C, -88°C, -86°C, -85°C, -84°C, and -82°C, specifically, dynamic viscoelastic spectrum analyzer DMA test: temperature range -100°C to +80°C, frequency 10Hz, dynamic strain 0.1%, prestress 1N, and heating rate of 3°C / min.

[0013] Compared with the traditional cis polybutadiene rubber or trans polybutadiene rubber combined with natural rubber, the products made of cis-butylene rubber can not only achieve excellent cold resistance, but also have higher practical application properties such as low-temperature elasticity and cut resistance, and have excellent comprehensive performance.

[0014] Preferably, the Mooney viscosity of the natural rubber according to ASTM D1646 standard is ≥70MU.

[0015] Preferably, the weight percentage of the carbon black is in the range of 45 parts, 50 parts, 55 parts, 60 parts or any two of them.

[0016] Under specific iodine absorption and oil absorption values, the inventors found that the amount of carbon black introduced not only affects some basic properties of the product such as modulus and toughness, but also affects the cold resistance of the product. When too much carbon black is added, the cold resistance and dynamic cutting resistance of the product will be significantly deteriorated, and the addition ratio needs to be strictly controlled.

[0017] Preferably, the kinematic viscosity of the rubber oil at 40°C is 8 to 36 mm 2 / s, pour point is -30~-24℃

[0018] More preferably, the rubber oil is plant-derived rubber oil.

[0019] Preferably, the raw materials for preparing the rubber composition further include 1 to 1.8 parts of an accelerator;

[0020] More preferably, the accelerator includes at least one of a thiazole accelerator, a sulfenamide accelerator, and a thiuram accelerator.

[0021] Preferably, the raw materials for preparing the rubber composition also include processing aids, including but not limited to antioxidants, tackifiers, dispersants, lubricants, catalysts, anti-reversion agents, and anti-scorch agents. Those skilled in the art may appropriately apply the above-mentioned processing aids to improve the processing efficiency and practicality of the product based on the application requirements of the actual product, without affecting the effects of the key raw materials in the product and the performance of the final product.

[0022] More preferably, the raw materials for preparing the rubber composition also include 3 to 8 parts of zinc oxide, 1 to 3 parts of stearic acid, 1 to 4 parts of dispersant, 1 to 4 parts of tackifier, 2 to 5 parts of antioxidant, 0.5 to 2 parts of anti-reversion agent and 0.1 to 0.4 parts of anti-scorch agent.

[0023] More preferably, the antioxidant is a mixture of an amine antioxidant, a quinoline antioxidant, and a wax antioxidant.

[0024] More preferably, the antioxidant is a mixture of N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, 2,2,4-trimethyl-1,2-dihydroquinoline and a wax antioxidant, and the mass ratio of the two is (1.5-2.5):(1-2):(0.5-1.5).

[0025] Preferably, the raw materials for preparing the rubber composition further include sulfur.

[0026] Another object of the present invention is to provide a method for preparing the rubber composition, comprising the following steps:

[0027] (1) natural rubber, cis-butylene rubber, stearic acid, zinc oxide, dispersant, tackifier and antioxidant are mixed in an internal mixer and subjected to rolling for 10 to 30 seconds, followed by adding carbon black and rolling and mixing to 100 to 115° C., adding rubber oil, rolling and mixing to 125 to 135° C., maintaining the temperature for 10 to 30 seconds, and then rolling and mixing again to 155 to 165° C., extruding and sheeting to obtain a mixed rubber;

[0028] (2) kneading the first-stage rubber mixture in an internal mixer to 120-135° C., maintaining the temperature for 10-30 seconds, and kneading the first-stage rubber mixture again to 145-155° C., extruding and tableting to obtain a second-stage rubber mixture;

[0029] (3) The second-stage mixed rubber, sulfur, accelerator, anti-reversion agent and anti-scorch agent are mixed in an internal mixer and rolled for 30 to 60 seconds and then held for 10 to 30 seconds, followed by a second rolling for 30 to 60 seconds and a second rolling for 10 to 30 seconds, and finally rolled and mixed at 95 to 115° C., extruded and sheeted to obtain the rubber composition.

[0030] Preferably, the interval time between each mixing section is 3 to 12 hours.

[0031] The preparation method of the rubber composition of the present invention has simple operation steps, low requirements on equipment, and can realize large-scale batch production.

[0032] Another object of the present invention is to provide a tire tread rubber, comprising the rubber composition of the present invention.

[0033] The rubber composition of the present invention has ideal cold-resistant performance, high grip in ice and snow environment, good cutting resistance; the cold resistance coefficient can reach 0.502-0.595, low low-temperature modulus, high elasticity, and the dynamic cutting amount can be as low as 1.24 cm 3 The following has excellent comprehensive performance and is very suitable for tire tread rubber, especially for all-steel radial engineering machinery tire tread rubber in low temperature environment and with high basic use requirements.

[0034] The beneficial effect of the present invention is that the present invention provides a rubber composition, which can achieve good performance in low temperature environment, high elasticity, good grip and good cut resistance by compounding cis-butylene rubber and natural rubber as a rubber matrix and introducing specific types of carbon black and rubber oil as compounding components. DETAILED DESCRIPTION

[0035] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments and comparative examples, the purpose of which is to understand the content of the present invention in detail, rather than to limit the present invention. All other embodiments obtained by those of ordinary skill in the art without making creative work premise belong to the protection scope of the present invention. The experimental reagents and instruments involved in the implementation of the present invention, unless otherwise specified, are all commonly used common reagents and instruments.

[0036] Example 1

[0037] An embodiment of the rubber composition of the present invention, a method for preparing the rubber composition, comprises the following steps:

[0038] (1) Rubber (natural rubber, cis-butylene rubber), stearic acid, zinc oxide, dispersant, tackifier, and antioxidant are mixed in an internal mixer and subjected to rolling for 20 seconds, followed by adding carbon black and rolling and mixing to 110° C., adding rubber oil, rolling and mixing to 130° C., maintaining the temperature for 20 seconds, and then rolling and mixing again to 160° C., extruding and sheeting to obtain a mixed rubber;

[0039] (2) kneading the first-stage rubber mixture in an internal mixer to 130° C., maintaining the temperature for 20 seconds, and kneading the mixture again to 150° C., extruding and tableting to obtain a second-stage rubber mixture;

[0040] (3) The second-stage mixed rubber, sulfur, accelerator, anti-reversion agent and anti-scorch agent are mixed in an internal mixer and rolled for 45 seconds and then held for 20 seconds, followed by a second rolling for 45 seconds and a second rolling for 20 seconds, and finally rolled and mixed at 110° C., extruded and sheeted to obtain the rubber composition.

[0041] The added materials and their weight portions are shown in Table 1.

[0042] Embodiments 2 to 8

[0043] An embodiment of the rubber composition of the present invention is different from Embodiment 1 only in the added materials and weight portions, as shown in Table 1.

[0044] Comparative Examples 1 to 14

[0045] A rubber composition, which differs from Example 1 only in the added materials and weight portions, as shown in Table 2.

[0046] The materials used in each embodiment and comparative example are as follows:

[0047] Rubber-1: natural rubber, STR20, Sri Trang Rubber Co., Ltd., Thailand;

[0048] Rubber-2: styrene-butadiene rubber, glass transition temperature -38°C, SBR1502, Sinopec Qilu Petrochemical Company;

[0049] Rubber-3: Nickel-based butadiene rubber, glass transition temperature -102°C, BR9000, Sinopec Qilu Petrochemical Company;

[0050] Rubber-4: lithium-based butadiene rubber, glass transition temperature -100°C, KBR820, Kumho Petrochemical Co., Ltd., South Korea;

[0051] Rubber-5: rare earth butadiene rubber, glass transition temperature -105°C, NdBR40, Kumho Petrochemical Co., Ltd., South Korea;

[0052] Rubber-6: trans-butylene-pentadiene rubber, glass transition temperature -71°C, TBIR2249, Shandong Jingbo Petrochemical Co., Ltd.;

[0053] Rubber-7: cis-butylene-pentadiene rubber, glass transition temperature -92°C, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences;

[0054] Rubber-8: cis-butylene-pentadiene rubber, glass transition temperature -90°C, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences;

[0055] Rubber-9: cis-butylene-pentadiene rubber, glass transition temperature -82°C, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences;

[0056] Rubber-10: cis-butylene-pentadiene rubber, glass transition temperature -79°C, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences;

[0057] Carbon black-1: N134, Cabot Corporation, USA, iodine absorption value is 142±5g / kg, DBP oil absorption value is 127±5×10 -5 m 3 / kg;

[0058] Carbon black-2: N220, Cabot Corporation, USA, iodine absorption value 121±5g / kg, DBP oil absorption value 114±5×10 -5 m 3 / kg;

[0059] Carbon black-3: N231, Cabot Corporation, USA, iodine absorption value 121±5g / kg, DBP oil absorption value 92±5×10 -5 m 3 / kg;

[0060] Carbon black-4: N347, Cabot Corporation, USA, iodine absorption value 90±5g / kg, DBP oil absorption value 124±5×10 -5 m 3 / kg;

[0061] Rubber oil-1: PIONIER TP130B, German Hansheng Group, kinematic viscosity (40℃) is 9mm 2 / s, pour point -30℃;

[0062] Rubber oil-2: VIVATEC 3307, German Hansheng Group, kinematic viscosity (40℃) is 36mm 2 / s, pour point -24℃;

[0063] Rubber oil-3: VIVATEC 4818, German Hansheng Group, kinematic viscosity (40℃) is 224mm 2 / s, pour point -24℃;

[0064] Rubber oil-4: VIVATEC 500, German Hansheng Group, kinematic viscosity (40℃) is 400mm 2 / s, pour point 30℃;

[0065] Zinc oxide: Zinc oxide (indirect process), Dalian Zinc Oxide Plant;

[0066] Stearic acid: Octadecanoic acid, Malaysian natural oil chemical;

[0067] Tackifier: SL1801, Huaqi (China) Chemical Co., Ltd.;

[0068] Dispersant: Atflow L-12, Kunshan Atman New Material Technology Co., Ltd.;

[0069] Antioxidant-1: N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD), Shengao Chemical Technology Co., Ltd.;

[0070] Antioxidant-2: 2,2,4-trimethyl-1,2-dihydroquinoline, Shengao Chemical Technology Co., Ltd.;

[0071] Anti-aging agent-3: OK2122H protective wax, Bairuimei Special Materials (Suzhou) Co., Ltd.;

[0072] Sulfur: IS60, Weilin New Materials Technology Co., Ltd.;

[0073] Accelerator-1: N-cyclohexyl-2-benzothiazolesulfenamide (CBS), Weilin New Materials Technology Co., Ltd.;

[0074] Accelerator-2: dibenzothiazyl disulfide (DM), Weilin New Materials Technology Co., Ltd.;

[0075] Anti-sulfurization reversion agent: WK-901 (1,3-bis(citricarboxylic imide methyl)benzene), Wuhan Jinghe Chemical Co., Ltd.;

[0076] Anti-scorch agent: N-cyclohexylthiophthalimide (CTP), Weilin New Materials Technology Co., Ltd.

[0077] Table 1

[0078]

[0079]

[0080] Table 2

[0081]

[0082]

[0083]

[0084] Effect Example 1

[0085] In order to verify the performance of the rubber composition of the present invention, the products obtained in each embodiment and comparative example were vulcanized (150° C., 60 min), and then the following tests were performed:

[0086] (1) -40℃ cold resistance coefficient test: refer to HG / T 3866-2008, test temperature -40℃, cooling for 5 minutes; compression rate 20%; the larger the cold resistance coefficient, the better the elastic recovery ability of the product at low temperature and the better the cold resistance performance;

[0087] (2) -40℃ E' modulus test: refer to GB / T40396-2021 method; the smaller the E' modulus, the better the grip performance of the product in low temperature environment;

[0088] (3) Glass transition temperature Tg test: refer to GB / T40396-2021 method; the lower the glass transition temperature, the wider the range of application of the product at low temperatures;

[0089] (4) Dynamic cutting test: Refer to T / CRIA 29003-2023 to test the dynamic cutting volume of the product, with a rotation speed of 720 rpm, a striking speed of 120 times / min, and a striking time of 20 minutes. The smaller the dynamic cutting volume, the better the cutting resistance of the product.

[0090] The test results are shown in Tables 3 and 4.

[0091] Table 3

[0092]

[0093] Table 4

[0094]

[0095] It can be clearly seen from the results that the rubber compositions prepared in the embodiments of the present invention have ideal cold resistance and performance after vulcanization, with a cold resistance coefficient of 0.502 to 0.595, an E' modulus of 133 to 215 MPa, a glass transition temperature of -60 to -55 ° C, and a dynamic cutting volume of 1.04 to 1.24 cm 3 .

[0096] The main reason why the products of each embodiment can exert this effect is the combination of the base rubber component and the selection of the types of carbon black and rubber oil used as the compound, as shown in Comparative Examples 1 to 5. In the products of Comparative Examples 1 to 3, different systems of cis-butyl rubber are combined with natural rubber as the base rubber, but the cold resistance coefficients of the three products are all less than 0.5, indicating that cis-butyl rubber does not have ideal cold resistance, and the E' modulus of these products is too high, and it is difficult to achieve high grip at low temperatures, and it is not suitable for tire tread rubber; the dynamic cutting volume of the products is generally larger than that of the embodiment products, and the cutting resistance is not high. The compound rubbers used in Comparative Examples 4 and 5 are trans-butylene rubber and conventional styrene-butadiene rubber. The cold resistance coefficients of the two products are lower, and the E' modulus of the product of Comparative Example 5 is even nearly 10 times that of the embodiment product, and the glass transition temperature is only -44°C. It may fail completely when used in a low temperature environment. However, in the product of the present invention, the glass transition temperature of the cis-butyl-pentyl rubber needs to be maintained within a specific range. If the value is too high or too low, as shown in Comparative Examples 6 and 7, in addition to the glass transition temperature of the product also changing, the product may not be able to balance low temperature performance and cut resistance. The product of Comparative Example 6 has good cold resistance, but the dynamic cutting amount is too high, while the product of Comparative Example 7 has a small dynamic cutting amount, good cut resistance, and unsatisfactory low temperature performance. In contrast, Examples 1 and 8 under the same system formula use appropriate cis-butyl-pentyl rubber, and the prepared products can balance cold resistance and cut resistance.

[0097] In addition, in the rubber component, the ratio of cis-butylene rubber to natural rubber also needs to be maintained within a specific range to achieve excellent comprehensive performance. As shown in Comparative Example 9, Example 4, Example 1, Example 3 and Comparative Example 8, it can be seen that when the addition ratio of natural rubber is too small, although the product has a high cold resistance coefficient, a low E' modulus, and good cold resistance, the dynamic cutting amount of the product is too large and does not have ideal cut resistance. As the content of natural rubber increases, the product can achieve a balance between cold resistance and cut resistance, but if it is too much, the cold resistance of the product will be significantly deteriorated.

[0098] On the other hand, in the product, the selection of carbon black is also the key factor affecting the product performance. As can be seen from Example 1, Example 5, and Comparative Examples 10 to 11, only carbon black with appropriate iodine absorption value and oil absorption value can achieve good bonding with rubber molecules. If only one of the conditions is met, as shown in Comparative Example 10, the iodine absorption value of the carbon black used in the product is the same as that used in Example 1, but the oil absorption value is lower, and the bonding strength between the carbon black and the rubber molecules in the product is insufficient, resulting in the aggravation of internal cracks caused by periodic impact inside, and a large dynamic cutting amount of the product; the oil absorption value of the carbon black used in the product described in Comparative Example 11 is the same as that used in Example 5, but the iodine absorption value is lower and does not meet the requirements of this scheme, and the cutting resistance of the product is also poor.

[0099] On the other hand, there are certain limitations on the amount of carbon black added. As shown in Example 1, Examples 6 to 7 and Comparative Example 12, although the more carbon black is added, the lower the production cost of the product, the various properties of the product are significantly deteriorated. Therefore, it is necessary to strictly control the ratio of carbon black to the rubber component.

[0100] In addition, the type of rubber oil in the product also needs to be carefully considered. As can be seen from Example 1, Example 8 and Comparative Examples 13 to 14, there are large differences in the cold resistance coefficients of products prepared from rubber oils with different kinematic viscosities and pour points. If the type is not selected properly, the cold resistance performance of the product may not reach the expected level.

[0101] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the present invention.

Claims

1. A rubber composition, characterized in that: The preparation comprises the following raw materials in parts by weight: 40-60 parts of cis-butylene rubber, 40-60 parts of natural rubber, 45-60 parts of carbon black, 1-5 parts of rubber oil; The glass transition temperature of the cis-butylene-pentadiene rubber is -90 to -82°C; The carbon black has an iodine absorption value of 115 to 165 g / kg and a DBP oil absorption value of 105 to 140×10 -5 m 3 / kg; The kinematic viscosity of the rubber oil at 40°C is ≤40 mm 2 / s, pour point ≤-24℃.

2. The rubber composition according to claim 1, characterized in that: The kinematic viscosity of the rubber oil at 40°C is 8 to 36 mm 2 / s, pour point is -30~-24℃.

3. The rubber composition according to claim 1, characterized in that: The raw materials for preparing the rubber composition also include 1 to 1.8 parts of an accelerator.

4. The rubber composition according to claim 3, characterized in that: The accelerator includes at least one of a thiazole accelerator, a sulfenamide accelerator, and a thiuram accelerator.

5. The rubber composition according to claim 1, characterized in that: The raw materials for preparing the rubber composition also include 3 to 8 parts of zinc oxide, 1 to 3 parts of stearic acid, 1 to 4 parts of dispersant, 1 to 4 parts of tackifier, 2 to 5 parts of antioxidant, 0.5 to 2 parts of anti-reversion agent and 0.1 to 0.4 parts of anti-scorch agent.

6. The rubber composition according to claim 5, characterized in that: The antioxidant is a mixture of amine antioxidants, quinoline antioxidants and wax antioxidants.

7. The rubber composition according to claim 1, characterized in that: The raw materials for preparing the rubber composition also include sulfur.

8. The method for preparing the rubber composition according to any one of claims 1 to 7, characterized in that: The following steps are involved: (1) natural rubber, cis-butylene rubber, stearic acid, zinc oxide, dispersant, tackifier and antioxidant are mixed in an internal mixer and subjected to rolling for 10 to 30 seconds, followed by adding carbon black and rolling and mixing to 100 to 115° C., adding rubber oil, rolling and mixing to 125 to 135° C., maintaining the temperature for 10 to 30 seconds, and then rolling and mixing again to 155 to 165° C., extruding and sheeting to obtain a mixed rubber; (2) kneading the first-stage rubber mixture in an internal mixer to 120-135° C., maintaining the temperature for 10-30 seconds, and kneading the first-stage rubber mixture again to 145-155° C., extruding and tableting to obtain a second-stage rubber mixture; (3) The second-stage mixed rubber, sulfur, accelerator, anti-reversion agent and anti-scorch agent are mixed in an internal mixer and rolled for 30 to 60 seconds and then held for 10 to 30 seconds, followed by a second rolling for 30 to 60 seconds and a second rolling for 10 to 30 seconds, and finally rolled and mixed at 95 to 115° C., extruded and sheeted to obtain the rubber composition.

9. The method for preparing the rubber composition according to claim 8, characterized in that: The interval time of each mixing section is 3 to 12 hours.

10. A tire tread rubber, characterized in that: The rubber composition comprises the rubber composition according to any one of claims 1 to 7.

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