Inner liner rubber composition, method for producing the same, and tire inner liner

Abstract

The application provides an inner lining rubber composition, a preparation method thereof and a tire inner lining, relates to the technical field of rubber manufacturing methods, and comprises a transition layer rubber composition and an air tight layer rubber composition, both of which comprise: a rubber base 100 parts; carbon black 50-60 parts; an activator 5-6 parts; a vulcanizing agent 0.6-2.6 parts; metal powder 2-8 parts; the air tight layer further comprises: chlorosulfonated polyethylene rubber 10-25 parts; nano clay 25-30 parts; tackifying resin 2-3 parts; plasticizer 3-4 parts; uniformizing agent 5-6 parts; the preparation method of the composition comprises adding the rubber base and then pressurizing; then adding other components to obtain a first rubber compound or a second rubber compound; and after stirring for 30-60 seconds, discharging the rubber compound. The application solves the problems of insufficient content of high-thermal-conductivity fillers or poor dispersion in the prior art, which leads to poor air tightness of the air tight layer and poor thermal conductivity of the transition layer, and achieves the technical effect of improving the service life.

Description

Technical Field

[0001] This invention relates to the field of rubber manufacturing techniques, and in particular to an inner liner rubber composition and its preparation method, and also to a method of using the inner liner rubber composition as the inner liner of a tire. Background Technology

[0002] The inner liner of a tire consists of an airtight layer and a transition layer. The airtight layer enhances the material's airtightness, effectively preventing gas leakage and ensuring the tire maintains proper pressure, thus improving vehicle safety and stability. The transition layer, on the other hand, increases thermal conductivity, helping to dissipate heat generated during tire operation, reducing internal tire temperature, slowing down tire material aging, and extending tire lifespan.

[0003] However, if the airtightness of the tire's airtight layer is poor, the tire pressure will gradually decrease, affecting not only the vehicle's driving stability and handling but also increasing fuel consumption and reducing tire lifespan. On the other hand, if the thermal conductivity of the transition layer is poor, the heat generated by the tire during operation cannot be dissipated effectively and in a timely manner, causing the internal temperature of the tire to become too high, accelerating the aging and damage of the tire materials, and in severe cases, even leading to safety accidents such as tire blowouts.

[0004] However, in the application of tire inner liner rubber compositions prepared by existing technologies, the inner liner still fails to meet the tire's usage requirements under high-intensity driving conditions due to insufficient content of high thermal conductivity fillers or poor dispersion of fillers in the rubber. Summary of the Invention

[0005] The purpose of this invention is to provide an inner lining rubber composition to alleviate the technical problem in the prior art where insufficient content or poor dispersion of high thermal conductivity fillers leads to insufficient air tightness of the airtight layer and insufficient thermal conductivity of the transition layer.

[0006] Another object of the present invention is to provide a method for preparing an inner lining rubber composition.

[0007] Another object of the present invention is to provide a tire inner liner using an inner liner rubber composition.

[0008] To achieve the above objectives, the technical solution of the present invention is as follows:

[0009] This invention provides an inner liner rubber composition, the inner liner comprising a transition layer rubber and an airtight layer rubber;

[0010] The transition layer rubber and the airtight layer rubber, by weight, both comprise the following components:

[0011] 100 parts rubber matrix; 50-60 parts carbon black; 5-6 parts activator; 0.6-2.6 parts vulcanizing agent; 2-8 parts metal powder;

[0012] The airtight layer rubber also includes the following components:

[0013] Chlorosulfonated polyethylene rubber 10-25 parts; nano clay 25-30 parts; tackifying resin 2-3 parts; plasticizer 3-4 parts; homogenizer 5-6 parts.

[0014] Furthermore, the rubber matrix includes at least one of natural rubber or brominated butyl rubber.

[0015] Furthermore, the activator includes zinc oxide and stearic acid; zinc oxide is 3 to 5 parts and stearic acid is 1 to 2 parts.

[0016] Furthermore, the vulcanizing agent includes an accelerator and sulfur; the accelerator is 0.5 to 2 parts, and the sulfur is 0.1 to 2.1 parts.

[0017] Furthermore, the accelerator includes at least one of sulfenamides, thiazoles, thiurams, thioureas, dithiocarbamates, aldehydes, guanidines, or xanthates.

[0018] Furthermore, the metal powder is iron powder with a particle size D50 of 0.3 μm to 1 μm.

[0019] Furthermore, the plasticizer includes at least one of petroleum-based plasticizers, coal tar-based plasticizers, or pine oil-based plasticizers.

[0020] The present invention also provides a method for preparing an inner lining rubber composition, comprising the following steps:

[0021] Step 1: Add 100 parts of rubber matrix to the internal mixer and pressurize it to obtain pressurized rubber;

[0022] Step 2: If a transition layer rubber is to be prepared, raise the pressure block and add 50-60 parts of carbon black, 5-6 parts of activator, 2-8 parts of metal powder and 0.6-2.6 parts of vulcanizing agent to the pressurized rubber in sequence for mixing to obtain the first compound rubber.

[0023] To prepare an airtight layer rubber, add 10-25 parts of chlorosulfonated polyethylene rubber to the pressurized rubber, then raise the pressure block, and then add 50-60 parts of carbon black, 5-6 parts of activator, 2-8 parts of metal powder, 25-30 parts of nano clay, 2-3 parts of tackifying resin, 3-4 parts of plasticizer, 5-6 parts of homogenizer, and 0.6-2.6 parts of vulcanizing agent in sequence to obtain a second compound rubber.

[0024] Step 3: Stir the first or second compound rubber for 30 to 60 seconds and then discharge the rubber to obtain the inner lining rubber composition.

[0025] Furthermore, in step 1, the pressure applied is 18MPa to 20MPa, and the pressure application time is 1min to 2min; in step 2, the mixing speed when mixing the first compound is 40r / min to 50r / min, and the mixing time is 5min to 10min; in step 2, the mixing speed when mixing the second compound is 50r / min to 60r / min, and the mixing time is 10min to 15min.

[0026] The present invention also provides a tire inner liner, which is prepared using an inner liner rubber composition.

[0027] Beneficial effects:

[0028] In this invention, the inner lining layer comprises a transition layer rubber and an airtight layer rubber. The composition of the transition layer rubber and the airtight layer rubber, by weight, each comprises: 100 parts of rubber matrix; 50-60 parts of carbon black; 5-6 parts of activator; 0.6-2.6 parts of vulcanizing agent; and 2-8 parts of metal powder. The airtight layer rubber further comprises: 10-25 parts of chlorosulfonated polyethylene rubber; 25-30 parts of nano-clay; 2-3 parts of tackifying resin; 3-4 parts of plasticizer; and 5-6 parts of homogenizer.

[0029] Adding 50-60 parts of carbon black to the transition layer rubber effectively enhances its strength, abrasion resistance, and electrical conductivity, while also improving its processing performance, resulting in better physical properties. The addition of metal powder increases thermal conductivity; metal powder possesses excellent thermal conductivity, enabling rapid heat transfer and effectively improving the thermal conductivity of the transition layer rubber.

[0030] The addition of metal powder to the airtight layer rubber can promote the combination of sulfur and rubber molecules, form more polysulfide bonds, increase the crosslinking sites in natural rubber, improve the crosslinking density, and thus enhance the airtightness of the material.

[0031] The preparation method of this invention is highly simple and easy to operate. The entire process does not involve complex or cumbersome operations, and the professional skill requirements for operators are relatively low, reducing the technical difficulty in the production process. Tires prepared using the tread rubber composition of this invention can dissipate heat in a timely manner, avoiding the degradation of rubber performance due to excessive temperature and extending the service life of the tire. Attached Figure Description

[0032] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0033] Figure 1 A flowchart illustrating a method for preparing an inner lining rubber composition according to an embodiment of the present invention. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0035] In a first aspect, the present invention provides an inner liner rubber composition, the inner liner rubber comprising a transition layer rubber and an airtight layer rubber;

[0036] The transition layer rubber and the airtight layer rubber, by weight, each comprise the following components: 100 parts rubber matrix; 50-60 parts carbon black; 5-6 parts activator; 0.6-2.6 parts vulcanizing agent; and 2-8 parts metal powder.

[0037] The airtight layer rubber also includes the following components: 10-25 parts of chlorosulfonated polyethylene rubber; 25-35 parts of nano clay; 2-3 parts of tackifying resin; 3-4 parts of plasticizer; and 5-6 parts of homogenizer.

[0038] In embodiments of the present invention, the carbon black may be, but is not limited to, 50 parts, 55 parts, or 60 parts by weight.

[0039] The activator can be, but is not limited to, 5 parts, 5.5 parts, or 6 parts by weight;

[0040] The vulcanizing agent can be, but is not limited to, 0.6 parts, 2.1 parts, or 2.6 parts by weight;

[0041] According to the parts by weight, the metal powder can be, but is not limited to, 2 parts, 4 parts, 6 parts or 8 parts;

[0042] According to the parts by weight, chlorosulfonated polyethylene rubber can be, but is not limited to, 10 parts, 20 parts or 25 parts;

[0043] The nano-clay can be, but is not limited to, 25 parts, 28 parts, or 30 parts by weight;

[0044] The tackifying resin may be, but is not limited to, 2 parts, 2.5 parts, or 3 parts by weight;

[0045] The plasticizer may be, but is not limited to, 3 parts, 3.5 parts, or 4 parts by weight;

[0046] The homogenizer can be, but is not limited to, 5 parts, 5.5 parts, or 6 parts by weight.

[0047] It should be noted that both the transition layer rubber and the airtight layer rubber are composed of 100 parts of rubber matrix. The rubber matrix provides the necessary flexibility, enabling the tire to adapt to deformation caused by various complex road conditions during driving, absorb vibration energy, reduce internal stress concentration caused by vibration, thereby improving the tire's fatigue resistance and extending the overall service life of the tire.

[0048] It should be noted that the 50-60 parts of carbon black added to the transition layer rubber and the airtight layer rubber can absorb and scatter ultraviolet rays, reduce the damage of ultraviolet rays to the rubber matrix, improve the weather resistance of the transition layer rubber, and make it less prone to aging and cracking during long-term outdoor use.

[0049] It should be noted that the addition of activators and vulcanizing agents can reduce the required vulcanization temperature during the vulcanization process. This not only saves energy but also reduces the adverse effects of high temperatures on the rubber matrix and other additives, thus helping to maintain the original properties of the rubber.

[0050] It should be noted that the 10-25 parts of chlorosulfonated polyethylene rubber added to the airtight layer rubber, in addition to high airtightness and aging resistance, also have good chemical corrosion resistance. It can resist the erosion of trace chemicals that may exist in the tire filling gas and some chemicals in the external environment, thus protecting the integrity of the airtight layer.

[0051] Two to three parts of tackifying resin can form a strong adhesive layer on the contact surface between the airtight layer rubber and other tire components, further enhancing the sealing effect. Even when the tire is subjected to greater pressure and deformation, it can effectively prevent gas from leaking from the connection between the airtight layer and other components.

[0052] Adding 3 to 4 parts of plasticizer can lower the glass transition temperature of the airtight layer rubber, prevent it from hardening and becoming brittle at low temperatures, and ensure that the airtight layer can maintain good elasticity at low temperatures, tightly adhere to the inside of the tire, and maintain good airtight performance.

[0053] Adding 5 to 6 parts of homogenizer can make the performance of the airtight layer rubber surface uniform and consistent, avoiding poor local airtightness or uneven mechanical properties, making the performance of various parts of the tire stable during use, and improving the overall reliability of the tire.

[0054] It should be noted that the metal powder added to the transition layer rubber is iron powder. This iron powder is uniformly dispersed within the rubber matrix, creating numerous heat conduction pathways within the rubber. Although the rubber matrix itself has poor thermal conductivity, the presence of the metal powder provides rapid heat conduction channels, allowing heat to be quickly transferred within the rubber, thereby improving the overall thermal conductivity of the transition layer rubber. Therefore, during tire operation, a significant amount of heat is generated due to friction with the road surface and stress changes within the tire. The increased thermal conductivity of the transition layer rubber with added iron powder allows this heat to be rapidly transferred from the tire's interior to the external environment, preventing heat buildup inside the tire.

[0055] The metal powder added to the airtight layer rubber, specifically iron powder, has a catalytic effect, promoting the bonding of sulfur with rubber molecules. During vulcanization, sulfur molecules in the vulcanizing agent normally require energy and time to react with rubber molecules. The addition of iron powder lowers the activation energy of the reaction, accelerating the bonding speed between sulfur and rubber molecules, thus forming more polysulfide bonds in a relatively short time. With the increase in crosslinking sites, the crosslinking density is significantly improved. Increased crosslinking density means stronger interactions between rubber molecular chains, making it less prone to relative sliding and deformation of the molecular chains when subjected to gas pressure. This effectively prevents gas molecule penetration and diffusion, enhancing the airtightness of the airtight layer.

[0056] In embodiments of the present invention, the rubber matrix includes one or more of natural rubber or brominated butyl rubber. For example, it can be natural rubber, brominated butyl rubber, or a mixture of the above.

[0057] In embodiments of the present invention, the activator comprises 3 to 5 parts of zinc oxide and 1 to 2 parts of stearic acid. For example, 3 parts of zinc oxide and 2 parts of stearic acid.

[0058] In embodiments of the present invention, the vulcanizing agent includes an accelerator and sulfur; the accelerator is 0.5 to 2 parts, and the sulfur is 0.1 to 2.1 parts. For example, 1 part of accelerator and 0.5 parts of sulfur can be mixed.

[0059] In embodiments of the present invention, the accelerator includes at least one selected from sulfenamides, thiazoles, thiurams, thioureas, dithiocarbamates, aldehyde amines, guanidines, or xanthates. For example, it can be a dithiocarbamate, a thiazole, or a mixture of the above.

[0060] In embodiments of the present invention, the metal powder is iron powder with a particle size D50 of 0.3 μm to 1 μm. When the median particle size is between 0.3 and 1 μm, it is easily and uniformly dispersed in the rubber matrix under the shear force of the internal mixer, forming a thermally conductive network in the transition layer. This increases the thermal conductivity by 20% to 30% compared to when no powder is added, effectively accelerating heat dissipation inside the tire and delaying rubber aging. In the airtight layer, the iron powder with this median particle size can catalyze the combination of sulfur and rubber molecules, increasing the crosslinking density by 15% to 20% and reducing the air permeability coefficient by 8% to 12%, significantly enhancing gas barrier properties. Conversely, if the particle size is too large (e.g., 40 to 50 μm iron powder), uneven dispersion will lead to filler accumulation, causing fluctuations in thermal conductivity and a decrease in airtightness.

[0061] In embodiments of the present invention, the plasticizer includes one or more of petroleum-based plasticizers, coal tar-based plasticizers, or pine resin-based plasticizers. For example, it can be petroleum-based, coal tar-based, or a mixture of the above.

[0062] Secondly, such as Figure 1 As shown, the present invention provides a method for preparing an inner lining rubber composition, which includes the following steps:

[0063] Step 1: Add 100 parts of rubber matrix to the internal mixer and pressurize it to obtain pressurized rubber; the pressure is 18MPa~20MPa and the pressing time is 1min~2min.

[0064] Step 2: If preparing a transition layer rubber, raise the pressure block and add 50-60 parts of carbon black, 5-6 parts of activator, 2-8 parts of metal powder, and 0.6-2.6 parts of vulcanizing agent to the pressurized rubber in sequence for mixing to obtain the first compound; the mixing speed of the first compound is 40-50 r / min, and the mixing time is 5-10 min.

[0065] To prepare an airtight layer rubber, add 10-25 parts of chlorosulfonated polyethylene rubber to the pressurized rubber, then raise the pressure block. Next, add 50-60 parts of carbon black, 5-6 parts of activator, 2-8 parts of metal powder, 25-30 parts of nano-clay, 2-3 parts of tackifying resin, 3-4 parts of plasticizer, 5-6 parts of homogenizer, and 0.6-2.6 parts of vulcanizing agent sequentially and mix to obtain a second compound. The mixing speed for the second compound is 50-60 r / min, and the mixing time is 10-15 min.

[0066] Step 3: Stir the first or second compound rubber for 30 to 60 seconds and then discharge the rubber to obtain the inner lining rubber composition.

[0067] The pressure applied in this invention is 18MPa to 20MPa, which helps the rubber matrix molecular chains to expand and orient, making its internal structure more regular and creating conditions for better mixing of various subsequently added components with the rubber matrix. Appropriate high pressure can eliminate impurities such as air in the rubber matrix, reduce defects such as pores inside the product, and improve the density and uniformity of the rubber product. The pressurization time is 1 to 2 minutes, within which the rubber matrix is ​​sufficiently subjected to pressure.

[0068] Transition layer rubber compounding: The compounding speed is 40 r / min to 50 r / min. This speed allows the added carbon black, activator, metal powder, and vulcanizing agent to be fully mixed with the pressurized rubber matrix in the internal mixer. This ensures that each component has sufficient time to undergo physical and chemical reactions with the rubber matrix, allowing the carbon black to better exert its reinforcing effect and the activator to fully activate the vulcanization reaction.

[0069] The mixing speed for the airtight layer rubber is 50 r / min to 60 r / min, slightly higher than that for the transition layer rubber. This is because the airtight layer rubber contains more components and has a more complex composition, requiring a higher speed to ensure that each component can be quickly and uniformly dispersed in the rubber matrix. The longer mixing time allows the chlorosulfonated polyethylene rubber to be fully blended with the rubber matrix, leveraging its unique performance advantages. Nano-clay can achieve good intercalation and dispersion in the rubber matrix, enhancing the rubber's mechanical properties and airtightness. Tackifying resins, plasticizers, and homogenizers can also fully function during this time, improving the compatibility between components and ultimately enhancing the overall performance of the airtight layer rubber.

[0070] Thirdly, the present invention also provides a method for using an inner liner rubber composition as the inner liner of a tire.

[0071] The features and performance of the present invention will be further described in detail below with reference to specific embodiments.

[0072] Example 1

[0073] This embodiment 1 provides an inner lining rubber composition, which, as the rubber at the transition layer, is composed of the following components by weight: 100 parts natural rubber; 50 parts carbon black; 5 parts activator (3 parts zinc oxide and 2 parts stearic acid); 2.1 parts vulcanizing agent (1.5 parts accelerator and 0.6 parts sulfur); and 4 parts metal powder (iron powder with a particle size of 1 μm and a D50).

[0074] The preparation method of this embodiment includes: adding a rubber matrix to a mixer and then pressurizing it to obtain pressurized rubber; the pressurization pressure is 18 MPa and the pressurization time is 1 min; raising the pressure block and mixing carbon black, activator, metal powder and vulcanizing agent added sequentially to the pressurized rubber to obtain a first compound; the mixing speed is 40 r / min and the mixing time is 5 min; the first compound is stirred for 30 s and then discharged.

[0075] Example 2

[0076] This embodiment 2 provides an inner lining rubber composition, which, as the rubber at the transition layer, is composed of the following components by weight: 100 parts natural rubber; 55 parts carbon black; 6 parts activator (5 parts zinc oxide and 1 part stearic acid); 2.5 parts vulcanizing agent (1.3 parts accelerator and 1.2 parts sulfur); and 6 parts metal powder (iron powder with a particle size of 1 μm and a D50).

[0077] The preparation method of this embodiment differs from that of Example 1 in that the pressure applied is 19 MPa and the pressure application time is 1.5 min; the mixing speed is 42 r / min and the mixing time is 8 min; and the first compound is stirred for 45 s before being discharged.

[0078] Example 3

[0079] This embodiment 3 provides an inner lining rubber composition, which, as the rubber at the transition layer, is composed of the following components by weight: 100 parts natural rubber; 50 parts carbon black; 6 parts activator (4 parts zinc oxide and 2 parts stearic acid); 2.6 parts vulcanizing agent (1.5 parts accelerator and 1.1 parts sulfur); and 8 parts metal powder (iron powder with a particle size of 1 μm and a D50).

[0080] The preparation method of this embodiment differs from that of Example 1 in that the pressure applied is 20 MPa and the time for applying the pressure is 2 min; the mixing speed is 45 r / min and the mixing time is 10 min; and the first compound is stirred for 60 s before being discharged.

[0081] Comparative Example 1

[0082] Comparative Example 1 provides a rubber composition for a transition layer in an inner liner, which is prepared in the same way as in Example 1, except that no metal powder (iron powder) is added to the components.

[0083] The tread rubber compositions obtained in Examples 1-3 were compared with those in Comparative Example 1 in terms of thermal conductivity and volume resistivity. The results are shown in Table 1.

[0084] Inner liner (transition layer adhesive) Comparative Example 1 Example 1 Example 2 Example 3 Iron powder (parts) 0 4 6 8 Iron powder particle size D50 (μm) 0 1 1 1 Thermal conductivity (W / m·℃) 0.23 0.25 0.31 0.3 Volume resistivity (Ω·cm) <![CDATA[2.73×10 6 ]]> <![CDATA[2.46×10 6 ]]> <![CDATA[2.21×10 6 ]]> <![CDATA[1.99×10 6 ]]>

[0085] Table 1

[0086] As shown in Table 1, the thermal conductivity is improved because the iron powder, evenly dispersed in the rubber matrix, provides a rapid heat conduction channel, allowing heat to be quickly transferred through the metal powder within the rubber, thus increasing the overall thermal conductivity of the transition layer rubber. In Comparative Example 1, without added iron powder, the thermal conductivity was 0.23 W / m·℃; in Examples 1-3, after adding iron powder, the thermal conductivity became 0.25 W / m·℃, 0.31 W / m·℃, and 0.3 W / m·℃, respectively. This indicates that adding iron powder to the components of the tire transition layer rubber improves the material's thermal conductivity, meaning its ability to conduct heat is enhanced, allowing for more efficient heat transfer. This improved thermal conductivity avoids problems such as rubber aging and performance degradation caused by heat accumulation, extending tire lifespan.

[0087] Furthermore, the volume resistivity also shows that iron powder has good conductivity, which can promote charge transport, indicating that the addition of iron powder affects the conductivity of the transition layer adhesive.

[0088] Example 4

[0089] Example 4 provides an inner lining rubber composition, which serves as the rubber for the airtight layer. It comprises the following components by weight: 100 parts rubber matrix (40 parts natural rubber and 60 parts brominated butyl rubber); 10 parts chlorosulfonated polyethylene rubber; 60 parts carbon black; 5.5 parts activator (3 parts zinc oxide and 2.5 parts stearic acid); 2.6 parts vulcanizing agent (1.6 parts accelerator and 1 part sulfur); 2 parts metal powder (0.3 μm particle size D50 iron powder); 25 parts nano-clay; 2 parts tackifying resin; 3 parts plasticizer; and 5 parts homogenizer.

[0090] The preparation method of this embodiment includes: adding a rubber matrix to a mixer and then pressurizing it to obtain pressurized rubber. The pressurization pressure is 18 MPa and the pressurization time is 1 min. After adding chlorosulfonated polyethylene rubber to the pressurized rubber, the pressure is raised. Carbon black, activator, metal powder, nano clay, tackifying resin, plasticizer, homogenizer and vulcanizing agent are added in sequence and mixed to obtain a second compound. The mixing speed is 50 r / min and the mixing time is 10 min. After stirring the second compound for 30 s, the rubber is discharged.

[0091] Example 5

[0092] This embodiment 5 provides an inner lining rubber composition, which serves as the rubber for the airtight layer. It comprises the following components by weight: 100 parts rubber matrix (40 parts natural rubber and 60 parts brominated butyl rubber); 20 parts chlorosulfonated polyethylene rubber; 60 parts carbon black; 6 parts activator (3 parts zinc oxide and 3 parts stearic acid); 2.6 parts vulcanizing agent (1.2 parts accelerator and 1.4 parts sulfur); 4 parts metal powder (0.3 μm particle size D50 iron powder); 28 parts nano-clay; 2.5 parts tackifying resin; 3.5 parts plasticizer; and 5.5 parts homogenizer.

[0093] The preparation method of this embodiment differs from that of Example 4 in that the pressure applied is 19 MPa and the pressure application time is 1.5 min; the mixing speed is 55 r / min and the mixing time is 13 min; and the second compound is stirred for 45 s before being discharged.

[0094] Example 6

[0095] This embodiment 6 provides an inner lining rubber composition, which serves as the rubber for the airtight layer. It comprises, by weight, the following components: 100 parts rubber matrix (40 parts natural rubber and 60 parts brominated butyl rubber); 25 parts chlorosulfonated polyethylene rubber; 60 parts carbon black; 6 parts activator (5 parts zinc oxide and 1 part stearic acid); 2 parts vulcanizing agent (0.8 parts accelerator and 1.2 parts sulfur); 6 parts metal powder (0.3 μm particle size D50 iron powder); 30 parts nano-clay; 3 parts tackifying resin; 4 parts plasticizer; and 5 parts homogenizer.

[0096] The preparation method of this embodiment differs from that of Example 4 in that the pressure applied is 20 MPa and the pressure time is 2 min; the mixing speed is 60 r / min and the mixing time is 15 min; and the second compound is stirred for 60 s before being discharged.

[0097] Comparative Example 2

[0098] Comparative Example 2 provides a rubber composition for use in the airtight layer of an inner liner, which is prepared in the same way as in Example 4, except that no metal powder (iron powder) is added to the components.

[0099] The tread rubber compositions obtained in Examples 4-6 were compared with those in Comparative Example 1 in terms of thermal conductivity and air permeability. The results are shown in Table 2.

[0100]

[0101]

[0102] Table 2

[0103] As shown in Table 2, the thermal conductivity gradually increases with the increase of iron powder content in the lining layer (airtight layer adhesive). This indicates that adding iron powder can effectively improve the thermal conductivity of the lining layer, and within a certain range, the more iron powder content, the higher the thermal conductivity.

[0104] Air permeability: At 23℃ before aging, the addition of iron powder alters the air permeability coefficient of the lining layer because iron powder promotes the bonding of sulfur with rubber molecules. During vulcanization, sulfur molecules in the vulcanizing agent normally require a certain amount of energy and time to react with rubber molecules. The addition of iron powder lowers the activation energy of the reaction, accelerating the bonding speed between sulfur and rubber molecules, thus forming more polysulfide bonds in a relatively short time. With stronger interactions between rubber molecular chains, the rubber in the airtight layer is less prone to relative sliding and deformation under gas pressure, effectively preventing gas molecule penetration and diffusion, and enhancing the airtightness of the airtight layer.

[0105] Furthermore, the air permeability coefficient fluctuates in Examples 4 to 6, which means that the air permeability of the material can be controlled by adjusting the amount of iron powder.

[0106] Finally, it should be noted that the specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A liner rubber composition, said liner rubber comprising a transition layer rubber and an airtight layer rubber, Its features are, The transition layer rubber and the airtight layer rubber each comprise the following components by weight: 100 parts rubber matrix; 50-60 parts carbon black; 5-6 parts activator; 0.6-2.6 parts vulcanizing agent; 2-8 parts metal powder; The airtight layer rubber also includes the following components: Chlorosulfonated polyethylene rubber 10-25 parts; nano clay 25-30 parts; tackifying resin 2-3 parts; plasticizer 3-4 parts; homogenizer 5-6 parts; The metal powder is iron powder, and the particle size D50 of the iron powder is 0.3μm to 1μm; The activator includes zinc oxide and stearic acid; the zinc oxide is 3-5 parts and the stearic acid is 1-2 parts. The vulcanizing agent includes an accelerator and sulfur; the accelerator is 0.5 to 2 parts, and the sulfur is 0.1 to 2.1 parts.

2. The inner lining rubber composition according to claim 1, characterized in that, The rubber matrix includes at least one of natural rubber or brominated butyl rubber.

3. The inner lining rubber composition according to claim 2, characterized in that, The accelerator includes at least one of sulfenamides, thiazoles, thiurams, thioureas, dithiocarbamates, aldehydes, guanidines, or xanthates.

4. The inner lining rubber composition according to claim 1, characterized in that, The plasticizer includes at least one of petroleum-based plasticizers, coal tar-based plasticizers, or pine oil-based plasticizers.

5. A method for preparing an inner lining rubber composition, used to prepare the inner lining rubber composition according to any one of claims 1 to 4, characterized in that, Includes the following steps: Step 1: Add 100 parts of the rubber matrix to a mixer and pressurize it to obtain pressurized rubber; Step 2: If the transition layer rubber is to be prepared, the pressure block is raised, and 50-60 parts of the carbon black, 5-6 parts of the activator, 2-8 parts of the metal powder and 0.6-2.6 parts of the vulcanizing agent are added sequentially to the pressurized rubber for mixing to obtain the first compound rubber. To prepare the airtight layer rubber, 10-25 parts of the chlorosulfonated polyethylene rubber are added to the pressurized rubber, and the pressure is raised. Then, 50-60 parts of the carbon black, 5-6 parts of the activator, 2-8 parts of the metal powder, 25-30 parts of the nano clay, 2-3 parts of the tackifying resin, 3-4 parts of the plasticizer, 5-6 parts of the homogenizer, and 0.6-2.6 parts of the vulcanizing agent are added sequentially and mixed to obtain the second compound rubber. Step 3: Stir the first or second compound rubber for 30 to 60 seconds and then discharge the rubber to obtain the inner lining rubber composition.

6. The method for preparing the inner lining rubber composition according to claim 5, characterized in that, In step 1, the pressure applied is 18MPa to 20MPa, and the pressure application time is 1min to 2min; in step 2, the mixing speed when mixing the first compound is 40r / min to 50r / min, and the mixing time is 5min to 10min; in step 2, the mixing speed when mixing the second compound is 50r / min to 60r / min, and the mixing time is 10min to 15min.

7. A tire inner liner, characterized in that, It is prepared using the inner lining rubber composition according to any one of claims 1 to 4.

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