High-airtightness rubber composition, preparation method thereof and tire

Abstract

The invention relates to the technical field of tire rubber manufacturing, and discloses a high-airtightness rubber composition, a preparation method thereof and a tire. The high-airtightness rubber composition is prepared by mixing the following raw materials based on 100 parts by weight of raw rubber: 15-25 parts of natural rubber, 75-85 parts of brominated butyl rubber, 45-65 parts of carbon black, 3-8 parts of argil, 25-35 parts of liquid nitrile rubber, 25-35 parts of hindered phenol, 2-2.5 parts of tackifying resin, and a proper amount of a vulcanization activator, an accelerant and a vulcanizing agent. According to the rubber composition, the carbon black and the argil are used as reinforcing fillers, the liquid nitrile rubber is used as a plasticizer, and the hindered phenol and the liquid nitrile rubber are compounded for use, so that the air tightness of the rubber composition is effectively improved.

Description

Technical Field

[0001] The invention relates to the technical field of tire rubber manufacturing, in particular to a high-airtightness rubber composition and a preparation method thereof and a tire. Background Art

[0002] Due to its unique high elasticity and sealing properties, rubber composites with high gas-liquid barrier properties play an irreplaceable role in the fields of tire airtight layers, medical plugs, chemical protection, and aerospace. With the expansion of application fields, higher requirements are put forward for barrier rubber. Butyl rubber has the best gas barrier properties among general synthetic rubbers, but it is still difficult to meet the needs of the above application fields. Therefore, the development of high-air-tightness butyl rubber composites and the regulation of material properties to cope with complex working conditions are of great significance to the development of the rubber industry and scientific and technological progress.

[0003] Bromobutyl rubber (BIIR) is a general-purpose synthetic rubber produced by introducing bromine gas during the preparation of butyl rubber. The highly active α-halogen atoms introduced improve the vulcanization speed and adhesion performance with other materials, which largely solves the problem of slow vulcanization speed and poor compatibility with other rubbers caused by the scarcity of double bonds in butyl rubber. BIIR itself has good damping performance and airtightness, but there is still room for improvement.

[0004] The penetration of small molecules in rubber mixtures mainly involves the following steps: (1) small molecule penetrants are adsorbed and dissolved on the rubber surface, (2) small molecule penetrants diffuse in the matrix, and (3) small molecule penetrants diffuse to the other surface of the rubber and desorb. The composition of rubber composites is not single. The rubber matrix, filler type and amount will affect the diffusion process. In addition, rubber usually needs to be cross-linked to realize its value. The introduction of cross-linking bonds often reduces the free volume between rubber chains, making gas diffusion more difficult.

[0005] In recent years, liquid rubber (LR-liquid rubber) is a type of viscous polymer with a relative molecular mass of 500-30000, which can flow at room temperature and can be added to the rubber matrix as a filler or reinforcing agent. There are many types of LR. In theory, each rubber has a corresponding liquid rubber, and a specific type of LR with functional groups in the chain or at the end of the chain can be obtained by monomer polymerization, rubber degradation, olefin metathesis, etc. The reason why the use effect of LR is better than that of traditional plasticizers is that on the one hand, it is due to the influence of physical crosslinking, which intensifies the entanglement of molecular chains, and on the other hand, the reactivity of LR enables it to participate in the crosslinking network. LR with good compatibility with the matrix and participating in crosslinking can be evenly dispersed in the matrix, overlap with the molecular chains, and occupy less free volume than the traditional plasticizer environmentally friendly aromatic oil (TDAE).

[0006] The traditional lining rubber formula has poor processability due to the addition of high fillers, so plasticizers are needed to adjust the processability. However, the traditional TDAE aromatic oil plasticizer may cause the problem of decreased air tightness. Therefore, in view of this, LR can be applied to the brominated butyl rubber formula, which can improve the processability of the rubber and improve the air tightness of the rubber.

[0007] The Chinese invention patent (publication number: CN113912955A, publication date: 2022.01.11) discloses a brominated butyl rubber composition for sealing materials and its preparation method. The composition, in parts by weight, consists of the following components: 80-110 parts of brominated butyl rubber, 0.5-1.5 parts of vulcanization accelerator, 0.5-2.0 parts of stearic acid, 40-70 parts of carbon black, 1-16 parts of liquid butyl rubber, 1-5 parts of zinc oxide, and 0.1-1.5 parts of sulfur. Liquid butyl rubber is added to the tire airtight layer rubber formula of the invention, which can be co-vulcanized with the brominated butyl rubber material, improves the dispersibility of carbon black, and improves the air tightness of the brominated butyl rubber airtight layer. The preparation process provided by the invention can reduce the mixing time, improve production efficiency and reduce energy consumption, while improving the dispersibility of carbon black. Summary of the invention

[0008] The invention aims at the deficiencies of the prior art and provides a high-air-tightness rubber composition. Liquid nitrile rubber and hindered phenol are added to the composition, so that a rubber composition with excellent comprehensive performance and excellent air-tightness can be prepared.

[0009] In order to achieve the above-mentioned purpose, the present invention adopts the following technical solutions: A high airtightness rubber composition, wherein the rubber composition is prepared by mixing the following raw materials based on 100 parts by weight of raw rubber: 15-25 parts of natural rubber, 75-85 parts of brominated butyl rubber, Carbon black 45-65 parts, 3-8 parts of clay, 25-35 parts of liquid nitrile rubber, Hindered phenol 25-35 parts, 2-2.5 parts of tackifying resin, And appropriate amounts of vulcanization activators, accelerators and vulcanizing agents.

[0010] Preferably, the rubber composition is prepared by mixing the following raw materials based on 100 parts by weight of raw rubber: Natural rubber 18-22 parts, 78-82 parts of brominated butyl rubber, Carbon black 50-60 parts, 4-6 parts of clay, Liquid nitrile rubber 28-32 parts, Hindered phenol 28-32 parts, 2-2.5 parts of tackifying resin, 4-6 parts of vulcanization activator, 2.5-3.5 parts of accelerator, Sulfur 1-5 parts.

[0011] Preferably, the hindered phenol is AO80 or AO70.

[0012] Preferably, the vulcanization activator is zinc oxide and stearic acid: zinc oxide is 1.0-4.0 parts, and stearic acid is 1.0-3.0 parts.

[0013] Preferably, the accelerators include accelerator CZ, accelerator DM and accelerator TMTD: accelerator CZ is 0.2-2.0 parts, accelerator DM is 0.2-2.0 parts, and accelerator TMTD is 0.2-1.0 parts.

[0014] Furthermore, the present invention also discloses a method for preparing the rubber composition, comprising the following steps: 1) One-stage mixing: use internal mixer for mixing; add natural rubber and brominated butyl rubber, press down the mass and keep it for 55-65 seconds; lift the mass, add 35%-45% carbon black and activator, press down the mass and keep it for 55-65 seconds; lift the mass and add 55%-65% carbon black, clay, liquid nitrile rubber, hindered phenol and tackifying resin, press down the mass and keep it for 80-100 seconds; lift the mass and clean it; 2) Second stage mixing: Use open mill for mixing; discharge rubber to open mill, adjust the roller distance of double roll open mill to 0.8-1.2mm, so that the rubber compound after mixing is wrapped around the roller; add accelerator and vulcanizer in sequence, cut the left and right knives three times each; make triangle wrapping five times when the roller is 0.15-0.25mm; adjust the roller distance to 1.5-2.0mm, unload the sheet, and park.

[0015] Furthermore, the present invention also discloses a high airtightness tire, which includes a tire inner liner, and the tire inner liner is prepared by vulcanizing the rubber composition.

[0016] The beneficial effects of the present invention are as follows: the invention uses carbon black and clay as reinforcing fillers, liquid nitrile rubber as a plasticizer, and hindered phenol is used in combination with liquid nitrile rubber. The use of liquid nitrile rubber with poor compatibility with the brominated butyl rubber matrix may reconstruct the entanglement network of the system, and the macromolecular chain and the filler are distributed more evenly. At the same time, part of the liquid nitrile rubber is cross-linked on the brominated butyl rubber molecular chain, and the molecular chain is further pulled closer through the strong interaction force of -CN. The uniform chain dispersion and entanglement network make the permeation path of gas molecules more tortuous during penetration, thereby causing a decrease in permeability. And the addition of hindered phenol enhances the interaction force between molecular chains, making the molecular chain movement more difficult, so the gas permeability decreases, thereby improving the air tightness of the rubber composition.

[0017] In the rubber composition of the present invention, in addition to the above-mentioned components, different additives can be mixed, such as other fillers commonly used in tires and other rubber compositions, vulcanizing agents, vulcanization accelerators, different types of oils, antioxidants, plasticizers, etc. These additives are mixed in a common way to obtain a rubber composition that can be used for vulcanization. The amount of these additives can also be a conventional, usually mixed amount, provided that the purpose of the present invention is not adversely affected. DETAILED DESCRIPTION

[0018] 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.

[0019] The formulations of the embodiments and comparative examples are shown in Table 1 (parts by weight).

[0020] The preparation methods of Examples 1-3 are as follows: 1) One-stage mixing: Mixing is performed using an internal mixer; natural rubber and brominated butyl rubber are added, and the pressing mass is pressed down and maintained for 55-65 seconds; the pressing mass is raised, 40% carbon black and activator are added, and the pressing mass is pressed down and maintained for 60 seconds; the pressing mass is raised, 60% carbon black, clay, liquid nitrile rubber, hindered phenol and tackifying resin are added, and the pressing mass is pressed down and maintained for 90 seconds; the pressing mass is raised and cleaned; 2) Second stage mixing: Use open mill for mixing; discharge rubber to open mill, adjust the roller distance of double-roll open mill to 1.0mm, so that the rubber compound wraps around the roller after mixing; add accelerator and vulcanizer in sequence, cut the left and right knives three times each; make triangle wrapping five times when the roller is 0.20mm; adjust the roller distance to 1.8mm, unload the sheet, and park.

[0021] The preparation method of Comparative Example 1-2 is as follows: 1) One-stage mixing: Mixing is carried out in an internal mixer; natural rubber and brominated butyl rubber are added, and the pressing mass is pressed down and kept for 55-65 seconds; the pressing mass is raised, 40% carbon black and activator are added, and the pressing mass is pressed down and kept for 60 seconds; the pressing mass is raised, 60% carbon black, clay, rubber operating oil and tackifying resin are added, and the pressing mass is pressed down and kept for 90 seconds; the pressing mass is raised and cleaned; 2) Second stage mixing: Use open mill for mixing; discharge rubber to open mill, adjust the roller distance of double-roll open mill to 1.0mm, so that the rubber compound wraps around the roller after mixing; add accelerator and vulcanizer in sequence, cut the left and right knives three times each; make triangle wrapping five times when the roller is 0.20mm; adjust the roller distance to 1.8mm, unload the sheet, and park.

[0022] The preparation methods of Comparative Examples 3-6 refer to the examples.

[0023] Table 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Example 1 Example 2 Example 3 Natural rubber*1 20 30 20 20 20 20 20 20 20 Butyl bromide*2 80 70 80 80 80 80 80 80 80 Carbon black*3 55 60 55 55 55 55 55 55 55 Clay*4 5 5 5 5 5 5 5 5 5 Liquid nitrile rubber*5 / / 10 20 30 / 30 25 35 Hindered phenol AO80*6 / / / / / 30　 30 35 25 Rubber operating oil*7 10 15 / / / / / / / Stearic acid*8 2 2 2 2 2 2 2 2 2 Resin*9 2.15 2.15 2.15 2.15 2.15 2.15 2.15 2.15 2.15 Zinc oxide*10 3 3 3 3 3 3 3 3 3 Accelerator*11 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8 0.8 Accelerator*12 1 1 1 1 1 1 1 1 1 Accelerator*13 0.9 0.9 0.9 0.9 0.9 0.9 0.9 0.9 0.9 Oil-filled sulfur*14 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 total 181.05 191.05 181.05 191.05 201.05 201.05 231.05 231.05 231.05 Table 1 Footnotes *1: SCR20, a product of Hainan Sinochem; *2: BIIR, a product of ExxonMobil; *3: N660, Cabot (Qingdao) Co., Ltd.; *4: Clay, a product of Tianjin Lulutong; *5: Liquid nitrile rubber LNBR29-1, a product of Hengshui Ruien Rubber & Plastic Technology Co., Ltd.; *6: Hindered phenol AO80, a product of Shanghai Kain Chemical Co., Ltd.; *7: V500, a product of Ningbo Hansheng; *8: Stearic acid, a product of Yihai Kerry; *9: Tackifying resin SL1801, Tongcheng Chemical Products; *10: Zinc oxide, product of Qingdao Haiyan Chemical Co., Ltd.; *11: Accelerator TMTD, a product of Shandong Shangshun Chemical Co., Ltd.; *12: Accelerator DM, a product of Shandong Shangshun Chemical Co., Ltd. *13: Feeding agent CBS (CZ), a product of Shandong Shangshun Chemical Co., Ltd.; *14: Oil-filled sulfur powder, a product of Wuxi Huasheng Rubber New Material Technology Co., Ltd.

[0024] The rubber compositions obtained in the examples and comparative examples were subjected to performance tests, and the test results are shown in Table 2.

[0025] The test method is as follows: 1) Vulcanization characteristics: According to GB / T 9869-1997 standard, the UR-2030 rotorless vulcanizer produced by Taiwan UCONN Company was used to measure the vulcanization curve and vulcanization characteristic parameters at 143°C and a swing angle of 1°.

[0026] 2) Tensile properties: The tensile strength and tear strength are in accordance with GB / T 528-2009 and GB / T 529-2008 standards. The tensile specimen is dumbbell-shaped and the tearing specimen is right-angled. The test is carried out using a U-CAN UT-2060 electronic tensile testing machine at a rate of 500 mm / min.

[0027] 3) Dynamic properties (DMA): The storage modulus (E′), loss modulus (E″) and loss factor (tanδ) of the rubber composition were measured using the VA3000 DMA produced by Metravib, France, with a temperature range of -60 to 80°C, a heating rate of 3°C / min, a frequency of 10 Hz, and a strain of 0.3%.

[0028] 4) Gas barrier performance: The nitrogen permeability coefficient of the sample was measured using the VAC-2C differential pressure airtightness instrument produced by Jinan Languang Electromechanical Technology Co., Ltd. The specific operation is as follows: ① Wipe the surface of the sample with ethanol and dry it, apply vacuum sealing silicone grease evenly on the test cavity, measure the sample thickness and put the sample into the test cavity and close the cavity; ② Open the nitrogen cylinder to adjust the air pressure between 0.4-0.5 MPa; ③ Turn on the vacuum pump and the temperature control box, and click on the operating computer to start the test. First, the vacuum pump evacuates the test cavity for about 12 hours to keep the pressure below 25 Pa; ④ After the vacuum time is reached, the nitrogen permeation test is started. When the pressure difference no longer changes with time, it reaches a stable permeability. The instrument will automatically terminate the test and calculate the gas permeability coefficient according to the prescribed procedure. The test sample uses a 1mm thick square sheet and the test temperature is 23℃.

[0029] Table 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Example 1 Example 2 Example 3 T90(min) 100 100 88 76 82 123 86 96 86 TB(MPa) 100 90 97 96 94 98 99 99 95 M300(MPa) 100 123 85 81 77 65 104 95 97 EB(%) 100 83 100 102 102 110 100 103 96 <![CDATA[Gas Permeability PN 2 (X10 -14 cm 3 / cm / cm 2 *s*Pa)]]> 100 142 99 98 97 100 85 92 88 Tanδ60℃ 100 109 100 102 105 109 77 89 92 Analyzing Table 2, Example 1 is the best example with the best comprehensive performance. Through Comparative Examples 1 and 2, it can be seen that in conventional formulas, increasing the amount of rubber oil added can improve the strength of the rubber, but will cause the gas permeability of the rubber to increase seriously. Comparative Examples 3-5 can show that the addition of liquid nitrile rubber can reduce the gas permeability, but has a greater impact on the rubber strength. The gas permeability of Examples 1-3 is reduced, and the rubber strength does not change much, and the heat generation at 60°C is also significantly reduced, which is suitable for the development direction of tire liner rubber formulas. Comparative Examples 5, 6 and Example 1 show that only adding liquid nitrile rubber or hindered phenol cannot achieve the effect of compounding the two.

[0030] 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 high airtightness rubber composition, characterized in that: The rubber composition is prepared by mixing the following raw materials based on 100 parts by weight of raw rubber: Natural rubber 15-25 parts, 75-85 parts of brominated butyl rubber, Carbon black 45-65 parts, 3-8 parts of clay, 25-35 parts of liquid nitrile rubber, Hindered phenol 25-35 parts, 2-2.5 parts of tackifying resin, And appropriate amounts of vulcanization activators, accelerators and vulcanizing agents.

2. The rubber composition according to claim 1, characterized in that The rubber composition is prepared by mixing the following raw materials based on 100 parts by weight of raw rubber: Natural rubber 18-22 parts, 78-82 parts of brominated butyl rubber, Carbon black 50-60 parts, 4-6 parts of clay, Liquid nitrile rubber 28-32 parts, Hindered phenol 28-32 parts, 2-2.5 parts of tackifying resin, 4-6 parts of vulcanization activator, 2.5-3.5 parts of accelerator, Sulfur 1-5 parts.

3. The rubber composition according to claim 1 or 2, characterized in that: The hindered phenol is AO80 or AO70.

4. The rubber composition according to claim 1 or 2, characterized in that: The vulcanization activator is zinc oxide and stearic acid: the zinc oxide is 1.0-4.0 parts, and the stearic acid is 1.0-3.0 parts.

5. The rubber composition according to claim 1 or 2, characterized in that: The accelerators include accelerator CZ, accelerator DM and accelerator TMTD: accelerator CZ is 0.2-2.0 parts, accelerator DM is 0.2-2.0 parts, and accelerator TMTD is 0.2-1.0 parts.

6. The method for preparing the rubber composition according to any one of claims 1 to 5, characterized in that: The following steps are involved: 1) One-stage mixing: use internal mixer for mixing; add natural rubber and brominated butyl rubber, press down the mass and keep it for 55-65 seconds; lift the mass, add 35%-45% carbon black and activator, press down the mass and keep it for 55-65 seconds; lift the mass and add 55%-65% carbon black, clay, liquid nitrile rubber, hindered phenol and tackifying resin, press down the mass and keep it for 80-100 seconds; lift the mass and clean it; 2) Second stage mixing: Use open mill for mixing; discharge rubber to open mill, adjust the roller distance of double roll open mill to 0.8-1.2mm, so that the rubber compound after mixing is wrapped around the roller; add accelerator and vulcanizer in sequence, cut the left and right knives three times each; make triangle wrapping five times when the roller is 0.15-0.25mm; adjust the roller distance to 1.5-2.0mm, unload the sheet, and park.

7. A high airtightness tire, characterized in that: The tire comprises a tire inner liner, and the tire inner liner is prepared by vulcanizing the rubber composition according to any one of claims 1 to 5.