A rubber for a tire transition layer, and a manufacturing method and application thereof

Abstract

The present application relates to a kind of tire transition layer rubber and manufacturing method and application, belong to rubber material technical field.Formula includes natural rubber 50~90 parts, epoxidized natural rubber 50~10 parts, carbon black 13.5~18 parts, white carbon black 31.5~42 parts, silane coupling agent 3.15~4.2 parts, zinc oxide 5~10 parts, antioxidant 1.5~3.5 parts, cobalt boryl 0.3~1.2 parts, stearic acid 0.5~1.5 parts, resorcinol 0.5~2 parts, zinc methacrylate 2~10 parts, adhesive 3~5 parts, insoluble sulfur 4.5~6 parts and accelerator 1.3~2.5 parts;The sum of natural rubber and epoxidized natural rubber component is 100 parts.Modified epoxidized natural rubber enhances the compatibility and vulcanization crosslinking effect of air tight layer, white carbon black is matched with coupling agent to realize the balance of bonding performance and processing performance, and zinc methacrylate can improve crosslinking density and physical properties in the process of rubber vulcanization with epoxidized natural rubber.

Description

Technical Field

[0001] This invention belongs to the field of rubber materials technology, specifically relating to a rubber for tire transition layers, its manufacturing method, and its application. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] All-steel radial truck tires have advantages such as high load-bearing capacity and high wear resistance, and are widely used in the transportation industry. In the structure of all-steel radial truck tires, the airtight layer prevents compressed gas leakage; the carcass ply, located outside the airtight layer, acts as the tire's load-bearing skeleton, maintaining internal tire pressure and transmitting load support; the airtight layer and the carcass ply are connected by a transition layer. Later in tire use, delamination can occur between the airtight layer and the carcass ply. Due to the complex stress states generated during vehicle operation, such as rolling deformation stress, road impact stress, and centrifugal force, coupled with reduced adhesion and inconsistent stress-strain between the airtight layer and the carcass ply, the airtight layer at the delamination point is prone to stretching and rupture. This allows air to leak in, causing the steel wires of the carcass ply to separate from the rubber, ultimately leading to a tire blowout or damage, seriously threatening driving safety.

[0004] In existing technologies, brominated butyl rubber is commonly used as the rubber phase in the airtight layer, utilizing its high polarity and high saturation to prevent gas permeation and ensure tire airtightness. The transition layer often employs a design approach similar to that of the tire cord rubber, leveraging the non-polarity and low saturation of natural rubber to provide better flexibility and processing performance. However, the significant structural differences between the natural rubber in the transition layer and the brominated butyl rubber in the airtight layer result in weak intermolecular forces, leading to poor compatibility and difficulty in forming a good bonding interface. Regarding the vulcanization system, the airtight layer typically uses oxide or resin vulcanizing agents, while the transition layer uses sulfur vulcanization. These differences in crosslinking reaction mechanisms prevent the formation of a tight, uniform crosslinked network at the interface, resulting in low crosslinking density and low bond strength, leading to poor stress transfer under stress. Currently, adding tackifiers to improve bonding is not ideal and may negatively impact other tire properties such as heat resistance, aging resistance, and elasticity, failing to fundamentally solve the problem of poor bonding between the transition layer and the airtight layer. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a rubber for tire transition layers, its manufacturing method, and its application. Natural rubber and modified epoxidized natural rubber are used as the rubber matrix materials in the transition layer formulation. Zinc methacrylate is added to enhance the interfacial crosslinking and adhesion between the transition layer and the airtight layer. The amount of silica added is also increased, and a silane coupling agent is used to balance the bonding and processing properties. The resulting rubber product not only ensures good adhesion to the tire carcass but also significantly improves the adhesion to the airtight layer, exhibiting durable strong adhesion. This effectively solves the delamination problem and improves the overall tire performance and safety reliability.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows:

[0007] In a first aspect, a rubber for a tire transition layer comprises the following components in parts by weight: 50-90 parts natural rubber, 50-10 parts epoxidized natural rubber, 13.5-18 parts carbon black, 31.5-42 parts silica, 3.15-4.2 parts silane coupling agent, 5-10 parts zinc oxide, 1.5-3.5 parts antioxidant, 0.3-1.2 parts cobalt borylate, 0.5-1.5 parts stearic acid, 0.5-2 parts resorcinol, 2-10 parts zinc methacrylate, 3-5 parts adhesive, 4.5-6 parts insoluble sulfur, and 1.3-2.5 parts accelerator; wherein the sum of the natural rubber and epoxidized natural rubber components is equal to 100 parts, and the mass ratio of silica to carbon black is (6-8):(2-4).

[0008] Secondly, a method for preparing the above-mentioned rubber for tire transition layers includes the following steps:

[0009] S1. Mix natural rubber and epoxidized natural rubber, and knead at 135~165℃ to obtain a first-stage rubber M1, and then cool.

[0010] S2. Mix the first-stage rubber M1, silica, carbon black, silane coupling agent, zinc oxide, antioxidant and stearic acid, and knead at 142~158℃ to obtain the second-stage rubber M2, and then cool.

[0011] S3. Mix the two-stage adhesive M2, cobalt borate and resorcinol, and knead at 135~145℃ to obtain the three-stage adhesive M3, and then cool.

[0012] S4. Mix the three-stage adhesive M3 and the binder, and knead at 105~115℃ to obtain the four-stage adhesive M4, and then cool.

[0013] S5. Mix the four-stage rubber M4, zinc methacrylate, insoluble sulfur and accelerator, and knead at 95~105℃ to obtain the rubber for the tire transition layer.

[0014] Thirdly, the application of the aforementioned rubber for tire transition layers includes: bonding the airtight layer and the carcass ply.

[0015] Optionally, the airtight layer comprises brominated butyl rubber, and the carcass ply comprises natural rubber.

[0016] The beneficial effects of this invention are as follows:

[0017] In terms of material system, this invention selects natural rubber and modified epoxidized natural rubber as the matrix. The former imparts good flexibility and cushioning performance to the transition layer, while the latter enhances the compatibility and vulcanization crosslinking effect with the airtight layer through polarity enhancement. Silica and carbon black are used as reinforcing materials in the formulation, along with a coupling agent at approximately 10 wt% of the silica content. This not only adjusts surface energy and improves cohesive strength but also improves filler dispersion and rubber bonding, achieving a balance between adhesion and processing performance. The polymerization, coordination, and interfacial interactions between zinc methacrylate and epoxy natural rubber strengthen the crosslinking adhesion between the transition layer and the airtight layer; furthermore, during rubber vulcanization, it works with epoxy natural rubber to improve crosslinking density and physical properties. The resulting novel transition layer formulation significantly improves interlayer adhesion and tack durability, optimizes tire structural stability, effectively solves delamination problems, and comprehensively enhances tire performance and safety reliability. Detailed Implementation

[0018] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0019] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0020] One or more embodiments of the present invention provide a rubber for a tire transition layer, comprising the following components in parts by weight: 50-90 parts natural rubber, 50-10 parts epoxidized natural rubber, 13.5-18 parts carbon black, 31.5-42 parts silica, 3.15-4.2 parts silane coupling agent, 5-10 parts zinc oxide, 1.5-3.5 parts antioxidant, 0.3-1.2 parts cobalt borylate, 0.5-1.5 parts stearic acid, 0.5-2 parts resorcinol, 2-10 parts zinc methacrylate, 3-5 parts adhesive, 4.5-6 parts insoluble sulfur, and 1.3-2.5 parts accelerator; wherein the sum of the natural rubber and epoxidized natural rubber components is equal to 100 parts, and the mass ratio of silica to carbon black is (6-8):(2-4).

[0021] In the above components, by systematically optimizing the material selection and component ratio of the transition layer formulation, the key contradictions such as poor interfacial compatibility caused by differences in rubber molecular structure and insufficient interfacial crosslinking density caused by incompatibility of vulcanization system have been solved, thus overcoming the technical problem of delamination between the airtight layer, transition layer and carcass.

[0022] Optionally, the natural rubber is STR20 grade with an acetone extract content of 1.5 to 3.2 wt%. Natural rubber has excellent comprehensive properties, giving the transition layer good flexibility, high elasticity and processing adaptability, and can effectively buffer the stress of the tire during driving.

[0023] Optionally, the epoxidized natural rubber has an epoxidation degree of 10% to 20%, and the optional models include one or both of ENR10 and ENR20; preferably, it is ENR10 with an epoxidation degree of 10%. The modified epoxidized natural rubber, by introducing epoxy groups, enhances the polarity of the rubber, improves the compatibility with brominated butyl rubber in the airtight layer, and strengthens the adhesion between the transition layer and the airtight layer. The high chemical activity of the epoxidized natural rubber also helps to optimize the vulcanization crosslinking network, and can work synergistically with the vulcanization system of the airtight layer to form additional crosslinking points at the interface, build a denser crosslinking network, significantly enhance the adhesion between the transition layer and the airtight layer, and improve the structural stability of the tire.

[0024] Optionally, the specific surface area of ​​the silica is 165±15m². 2 / g; Compared with carbon black, silica has a higher specific surface area and stronger surface activity. It can adjust the surface energy of the transition layer to promote tight adhesion with the airtight layer, and can also react with epoxidized natural rubber to enhance the cohesive strength of the transition layer.

[0025] Optionally, the carbon black is selected from one or more of N326, N375 and N330.

[0026] Optionally, the silane coupling agent is selected from one or two of bis-(3-(triethoxysilane)propyl)tetrasulfide (abbreviated as Si-69) and bis-(3-(triethoxysilane)propyl)disulfide (abbreviated as Si-75);

[0027] The reaction between silane coupling agents and silica is relatively complex. Through the cross-linking reaction of their thioalkyl groups with rubber molecular chains, stable chemical bonds are formed. Furthermore, the triethoxysilane groups react with the hydroxyl groups on the surface of silica to enhance the interfacial bonding between the filler and the rubber matrix. This dual effect improves the mechanical properties of the rubber, reduces hysteresis loss, and enhances the overall performance of the material.

[0028] Optionally, the zinc oxide has a specific surface area of ​​8.0 ± 1.0 m². 2 / g, used in rubber to react with fatty acids to produce zinc soap, which acts as a strong catalyst for vulcanization, accelerating sulfur crosslinking and increasing network density.

[0029] Cobalt borylate is used to promote chemical bonding with steel wire and ensure adhesion performance. The added resorcinol (a phenolic substance) reacts with other components to generate a high-adhesion structure, and a high amount of insoluble sulfur is used to ensure copper bridging with the steel wire surface. It is a component that enables effective connection between the transition layer and the carcass ply.

[0030] Optionally, the antioxidant is selected from one or more of antioxidants 6PPD, DTPD, and 4010NA. Its function is to capture free radicals and inhibit oxidation reactions in the rubber to delay the aging process of the rubber, thereby improving the rubber's resistance to heat and oxygen aging and its resistance to ozone.

[0031] Optionally, the stearic acid has the following properties: iodine value ≤ 8.0 g / 100 g, acid value 196–211 mg / g, freezing point 52–60 °C, saponification index 197–212 mg KOH / g, and C... 18 and C 16 The total content of these components is ≥88wt%; their function is to react with zinc oxides in the rubber to form zinc soap, which promotes the vulcanization reaction.

[0032] Optionally, the adhesive is selected from one or both of adhesives RA65 and HMT.

[0033] Optionally, the insoluble sulfur is selected from OT20.

[0034] Optionally, the accelerator is selected from one or more of accelerator DZ, accelerator NS, and accelerator CZ.

[0035] The chemical formula of zinc methacrylate is shown below:

[0036] .

[0037] The interaction mechanism of zinc methacrylate with epoxy natural rubber includes three aspects: polymerization reinforcement, coordination, and interfacial interaction: (1) During rubber vulcanization, its double bonds self-polymerize to form a polyzinc methacrylate phase to reinforce the rubber matrix; (2) Zinc ions in polyzinc methacrylate coordinate with oxygen atoms in epoxy natural rubber, improving crosslinking density and physical properties; (3) The polarity of epoxy natural rubber and the reactivity of epoxy groups cause it to generate strong interfacial interaction with zinc methacrylate; the polymerization of zinc methacrylate during vulcanization can also improve its own dispersion in the rubber matrix, thereby improving material properties. This is different from the interaction mechanism of other rubbers: In non-polar rubbers, zinc methacrylate is initiated by peroxides, causing the rubber matrix to crosslink and homopolymerize itself, forming an ionic crosslinking network through graft polymerization, and polyzinc methacrylate can also separate into nanoparticles to play a reinforcing role; for polar rubbers such as hydrogenated nitrile rubber and brominated butyl rubber, the two have good compatibility, and in addition to crosslinking, they can also improve tear strength and high temperature performance. In contrast, the coordination of zinc ions with epoxy groups and the strong interfacial interaction are unique features of zinc methacrylate in epoxy natural rubber. Based on the above principle, it simultaneously enhances the interfacial crosslinking and adhesion between the transition layer and the airtight layer.

[0038] One or more embodiments of the present invention provide a method for preparing the above-mentioned rubber for tire transition layers, comprising the following steps:

[0039] S1. Mix natural rubber and epoxidized natural rubber, and knead at 135~165℃ to obtain a first-stage rubber M1, and then cool.

[0040] S2. Mix the first-stage rubber M1, silica, carbon black, silane coupling agent, zinc oxide, antioxidant and stearic acid, and knead at 142~158℃ to obtain the second-stage rubber M2, and then cool.

[0041] S3. Mix the two-stage adhesive M2, cobalt borate and resorcinol, and knead at 135~145℃ to obtain the three-stage adhesive M3, and then cool.

[0042] S4. Mix the three-stage adhesive M3 and the binder, and knead at 105~115℃ to obtain the four-stage adhesive M4, and then cool.

[0043] S5. Mix the four-stage rubber M4, zinc methacrylate, insoluble sulfur and accelerator, and knead at 95~105℃ to obtain the rubber for the tire transition layer.

[0044] Optionally, in S1~S4, the cooling method includes: tableting and cooling for 8 hours.

[0045] Optionally, in S1, the internal mixer speed is 40~50 rpm and the top plug pressure is 0.55~0.60 MPa.

[0046] Optionally, in S2, the internal mixer speed is 20~50 rpm and the top plug pressure is 0.55~0.60 MPa.

[0047] Optionally, in S3, the internal mixer speed is 35~40 rpm and the top plug pressure is 0.55~0.60 MPa.

[0048] Optionally, in S4, the internal mixer speed is 16~22 rpm and the top plug pressure is 0.45~0.50 MPa.

[0049] Optionally, in S5, the internal mixer speed is 15~25 rpm and the top plug pressure is 0.45~0.50 MPa.

[0050] One or more embodiments of the present invention provide the application of the above-described tire transition layer rubber, including: for bonding the airtight layer and the carcass ply.

[0051] Optionally, the airtight layer comprises brominated butyl rubber, and the carcass ply comprises natural rubber.

[0052] Example 1

[0053] A rubber for tire transition layers comprises the following components in parts by weight: 70 parts natural rubber, 30 parts epoxidized natural rubber, 15 parts carbon black, 35 parts silica, 3.5 parts silane coupling agent, 8 parts zinc oxide, 2.5 parts antioxidant, 0.8 parts cobalt borate, 1 part stearic acid, 1.2 parts resorcinol, 3.5 parts zinc methacrylate, 4 parts adhesive, 5 parts insoluble sulfur, and 2 parts accelerator.

[0054] The acetone extract of natural rubber STR20 is 1.5% to 3.2%.

[0055] The epoxidized natural rubber selected was ENR10 with an epoxidation degree of 10%.

[0056] Carbon black N326 was selected.

[0057] Silica content ≥92.0%, loss on heating (105℃) 5.5±1.5, loss on ignition ≤6.0, specific surface area 165±15m² 2 / g.

[0058] The silane coupling agent selected is Si-69, which contains 22.5±0.8% sulfur, 17.5±2.0% S2, 30.0±2.0% S3, 20.5±2.0% S4, 24.5±2.0% S5 to S8, and an average polysulfide bond length of 3.30±0.1.

[0059] The zinc oxide is produced by indirect method, with a zinc oxide content ≥99.50% and a specific surface area of ​​8.0±1.0 m².2 / g.

[0060] The antioxidant was selected as 6PPD, in which the content of N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine was ≥96.0wt%.

[0061] The cobalt content in boronyl cobalt is 22.5 ± 0.7 wt%.

[0062] Stearic acid, with an iodine value ≤8.0g / 100g, an acid value of 196~211mg / g, a freezing point of 52~60℃, a saponification index of 197~212mgKOH / g, and a C18+C16 content ≥88%.

[0063] The DSC melting point of resorcinol is 110.0–114.0 °C.

[0064] The adhesive selected is RA65, which contains 34.0±2.5wt% acetone-insoluble matter and 30-35wt% ash (850℃).

[0065] The insoluble sulfur was selected as OT20, with an oil content of 19.5±1.5%, a total sulfur content of 80.0±1.5%, a thermal reduction rate of ≤25%, and a DSC melting point of 132.0±6.0℃.

[0066] Accelerator DZ was selected, with sulfenamide content (oil-free) ≥97% and cyclohexane insoluble matter ≤0.5%.

[0067] The zinc methacrylate contains ≥98.0 wt% active ingredient, ≤2.0 wt% moisture, pH 5–7, 35–38 wt% ZnO content, ≤38 wt% ash content, and 30–35 m² specific surface area. 2 / g.

[0068] Preparation methods include:

[0069] S1. Use a GK420 internal mixer to produce the first-stage rubber M1. Set the internal mixer speed to 50 rpm, the top jack pressure to 0.55 MPa, and the water temperature in the mixing chamber to 35±5℃. Add the natural rubber and epoxidized natural rubber mixture to the internal mixer, press down the top jack and hold for 40 seconds until the pressure reaches the set value. Then lift the top jack and hold for 5 seconds. Press down the top jack and hold until the rubber temperature reaches 135℃, then lift the top jack. Press down the top jack and hold until the rubber temperature reaches 165℃, then drain the rubber from the internal mixer to a twin-screw extruder (parameter settings: distance between the two rollers set to 8cm~15cm, roller temperature 100±5℃, screw temperature 95±10℃). Press the first-stage rubber M1 into sheets, cool and let stand for 8 hours for later use.

[0070] S2. Use a GK420 internal mixer to prepare the second-stage rubber M2. Set the mixer speed to 48 rpm, the top plug pressure to 0.55 MPa, and the mixing chamber water temperature to 35±5℃. Add the first-stage rubber M1 to the mixer, press down the top plug and hold for 20 seconds until the pressure reaches the set value. Then lift the top plug and add silica, carbon black N326, silane coupling agent, zinc oxide, antioxidant, and stearic acid. Press down the top plug again and hold for 30 seconds. At this time, adjust the mixer speed to 35 rpm, then lift... Add antioxidant to the top bolt and hold for 5 seconds; then press down the top bolt and hold until the rubber compound temperature reaches 142℃, at which point the internal mixer speed is adjusted to 20 rpm; then lift the top bolt and hold for 60 seconds; then press down the top bolt and hold until the rubber compound temperature reaches 158℃, then drain the rubber compound from the internal mixer to a twin-screw extruder (parameter settings: distance between the two rollers set to 5cm~8cm, roller temperature 95±5℃, screw temperature 85±10℃), and press the second-stage rubber M2 into tablets, cool and let stand for 8 hours for later use.

[0071] S3. Use a GK420 internal mixer to produce three-stage rubber M3. Set the internal mixer speed to 35 rpm, the top jack pressure to 0.55 MPa, and the water temperature in the mixing chamber to 35±5℃. Add two-stage rubber M2, cobalt borate, and resorcinol to the internal mixer. Press down the top jack and hold for 40 seconds until the pressure reaches the set value. Then lift the top jack and hold for 5 seconds. Press down the top jack and hold for 40 seconds. Then lift the top jack and hold for 5 seconds. Press down the top jack and hold until the rubber compound temperature reaches 145℃. Then drain the rubber compound from the internal mixer to a twin-screw extruder (parameter settings: distance between the two rollers set to 5cm~10cm, roller temperature 95±10℃, screw temperature 85±10℃). Press the three-stage rubber M3 into tablets, cool, and let stand for 8 hours for later use.

[0072] S4. Use a GK255 internal mixer to produce four-stage rubber M4. Set the internal mixer speed to 22 rpm, the top jack pressure to 0.45 MPa, and the water temperature in the mixing chamber to 30±5℃. Add three-stage rubber M3 and the binder to the internal mixer, press down the top jack and hold for 35 seconds until the pressure reaches the set value. Then lift the top jack and hold for 5 seconds. Press down the top jack and hold for 25 seconds, then lift the top jack and hold for 5 seconds. Press down the top jack and hold until the rubber temperature reaches 115℃. Then drain the rubber from the internal mixer to an open mill for sheeting (parameter settings: the distance between the two rollers is set to 5cm~10cm, and the roller temperature is <70℃). Let the four-stage rubber M4 sheets cool and stand for 8 hours for later use.

[0073] S5. Use a GK255 internal mixer to prepare the final rubber compound. Set the mixer speed to 22 rpm, the top jack pressure to 0.45 MPa, and the mixing chamber water temperature to 30±5℃. Add the fourth-stage rubber M4, zinc methacrylate, insoluble sulfur, and accelerator to the internal mixer. Press down the top jack and hold for 30 seconds until the pressure reaches the set value. Then lift the top jack and hold for 5 seconds. Press down the top jack and hold for 20 seconds. At this time, adjust the internal mixer speed to 16 rpm. Then lift the top jack and hold for 5 seconds. Press down the top jack and hold until the rubber compound temperature reaches 105℃. Then drain the rubber compound from the internal mixer to an open mill for sheeting (parameter settings: the distance between the two rollers is set to 5cm~10cm, and the roller temperature is <70℃). The final rubber compound is sheeted for subsequent processes to make the tire tread.

[0074] Example 2

[0075] A tire transition layer rubber comprises the following components in parts by weight: 50 parts natural rubber, 50 parts epoxidized natural rubber, 18 parts carbon black, 42 ​​parts silica, 4.2 parts silane coupling agent, 10 parts zinc oxide, 3.5 parts antioxidant, 1.2 parts cobalt borate, 1.5 parts stearic acid, 2 parts resorcinol, 10 parts zinc methacrylate, 5 parts binder, 6 parts insoluble sulfur, and 2.5 parts accelerator; the epoxidized natural rubber is selected as ENR50 with a degree of epoxidation of 50%.

[0076] The difference from Example 1 is that each material component is within the upper threshold range of the example.

[0077] The specifications and preparation methods for each raw material are the same as in Example 1.

[0078] Example 3

[0079] A rubber for tire transition layers comprises the following components in parts by weight: 90 parts natural rubber, 10 parts epoxidized natural rubber, 13.5 parts carbon black, 31.5 parts silica, 3.15 parts silane coupling agent, 5 parts zinc oxide, 1.5 parts antioxidant, 0.3 parts cobalt borate, 0.5 parts stearic acid, 0.5 parts resorcinol, 2 parts zinc methacrylate, 3 parts adhesive, 4.5 parts insoluble sulfur, and 1.3 parts accelerator.

[0080] The difference from Example 1 is that each material component is within the lower threshold range of the example.

[0081] The specifications and preparation methods for each raw material are the same as in Example 1.

[0082] Comparative Example 1

[0083] A rubber for tire transition layers comprises the following components in parts by weight: 100 parts natural rubber, 50 parts carbon black, 10 parts silica, 8 parts zinc oxide, 2 parts antioxidant, 1 part cobalt borate, 0.5 parts stearic acid, 1 part resorcinol, 3 parts adhesive, 5 parts insoluble sulfur, and 1.4 parts accelerator.

[0084] The main difference from Example 1 is that epoxy natural rubber, silane coupling agent, and zinc methacrylate are not added, and the amount of carbon black added is increased while the amount of silica added is reduced.

[0085] The specifications for each raw material are the same as in Example 1.

[0086] The preparation method can be adjusted appropriately based on the raw materials, including:

[0087] S1. Use a GK420 internal mixer to produce primary rubber M1. Set the mixer speed to 48 rpm, the top plug pressure to 0.55 MPa, and the water temperature in the mixing chamber to 35±5℃. Add natural rubber to the mixer, press down the top plug and hold for 20 seconds until the pressure reaches the set value. Then lift the top plug and add silica, carbon black N326, zinc oxide, antioxidant, and stearic acid. Press down the top plug again and hold for 30 seconds. At this time, adjust the mixer speed to 35 rpm, and then lift the top plug. Add antioxidant and hold for 5 seconds; then press down the top bolt and hold until the rubber compound temperature reaches 142℃, at which point adjust the internal mixer speed to 20 rpm; then lift the top bolt and hold for 60 seconds; then press down the top bolt and hold until the rubber compound temperature reaches 158℃, then drain the rubber compound from the internal mixer to a twin-screw extruder (parameter settings: the distance between the two rollers is set to 5cm~8cm, the roller temperature is 95±5℃, and the screw temperature is 85±10℃), and press a section of rubber M1 into tablets, cool and let stand for 8 hours for later use.

[0088] S2. Use a GK420 internal mixer to produce the second-stage rubber M2. Set the internal mixer speed to 35 rpm, the top jack pressure to 0.55 MPa, and the water temperature in the mixing chamber to 35±5℃. Add the first-stage rubber M1, cobalt borate, and resorcinol to the internal mixer. Press down the top jack and hold for 40 seconds until the pressure reaches the set value. Then lift the top jack and hold for 5 seconds. Press down the top jack and hold for 40 seconds. Then lift the top jack and hold for 5 seconds. Press down the top jack and hold until the rubber compound temperature reaches 145℃. Then drain the rubber compound from the internal mixer to a twin-screw extruder (parameter settings: distance between the two rollers set to 5cm~10cm, roller temperature 95±10℃, screw temperature 85±10℃). Press the second-stage rubber M2 into tablets, cool, and let stand for 8 hours for later use.

[0089] S3. Use a GK255 internal mixer to produce three-stage rubber M3. Set the internal mixer speed to 22 rpm, the top jack pressure to 0.45 MPa, and the water temperature in the mixing chamber to 30±5℃. Add two-stage rubber M2 and the binder to the internal mixer, press down the top jack and hold for 35 seconds until the pressure reaches the set value. Then lift the top jack and hold for 5 seconds. Press down the top jack and hold for 25 seconds, then lift the top jack and hold for 5 seconds. Press down the top jack and hold until the rubber temperature reaches 115℃. Then drain the rubber from the internal mixer to an open mill for sheeting (parameter settings: the distance between the two rollers is set to 5cm~10cm, and the roller temperature is <70℃). Let the three-stage rubber M3 sheets cool and stand for 8 hours for later use.

[0090] S4. Use a GK255 internal mixer to prepare the final rubber compound. Set the mixer speed to 22 rpm, the top jack pressure to 0.45 MPa, and the mixing chamber water temperature to 30±5℃. Add the third-stage rubber M3, insoluble sulfur, and accelerator to the internal mixer. Press down the top jack and hold for 30 seconds until the pressure reaches the set value. Then lift the top jack and hold for 5 seconds. Press down the top jack and hold for 20 seconds. At this time, adjust the internal mixer speed to 16 rpm. Then lift the top jack and hold for 5 seconds. Press down the top jack and hold until the rubber compound temperature reaches 105℃. Then drain the rubber compound from the internal mixer to an open mill for sheeting (parameter settings: the distance between the two rollers is set to 5cm~10cm, and the roller temperature is <70℃). The final rubber compound is sheeted for subsequent processes to make the tire tread.

[0091] Comparative Example 2

[0092] A tire transition layer rubber comprises the following components in parts by weight: 70 parts natural rubber, 30 parts epoxidized natural rubber, 50 parts carbon black, 10 parts silica, 8 parts zinc oxide, 2 parts antioxidant, 1 part cobalt borate, 0.5 parts stearic acid, 1 part resorcinol, 3 parts adhesive, 5 parts insoluble sulfur, and 1.4 parts accelerator.

[0093] The difference from Comparative Example 1 is that 30 parts of the natural rubber were replaced with epoxy natural rubber.

[0094] Other raw material requirements are the same as in Example 1.

[0095] The preparation method can be adjusted appropriately based on the raw materials, including:

[0096] S1. This step is the same as step S1 in Example 1. At the end of the step, a piece of adhesive is obtained.

[0097] S2. This step is the same as step S1 of Comparative Example 1, except that: the first-stage rubber of this comparative example is used instead of the natural rubber of Comparative Example 1, and a second-stage rubber is obtained after the step is completed.

[0098] S3. This step is the same as step S2 of Comparative Example 1, except that the two-stage glue of this comparative example is used instead of the one-stage glue of Comparative Example 1. After the step is completed, a three-stage glue is obtained.

[0099] S4. This step is the same as step S3 of Comparative Example 1, except that the three-stage glue of this comparative example is used instead of the two-stage glue of Comparative Example 1, and a four-stage glue is obtained after the step.

[0100] S5. This step is the same as step S4 of Comparative Example 1, except that the four-stage rubber of this comparative example is used instead of the three-stage rubber of Comparative Example 1. After the step is completed, the final rubber is obtained.

[0101] Comparative Example 3

[0102] A rubber for tire transition layers comprises the following components in parts by weight: 70 parts natural rubber, 30 parts epoxidized natural rubber, 50 parts carbon black, 10 parts silica, 8 parts zinc oxide, 2 parts antioxidant, 1 part cobalt borate, 0.5 parts stearic acid, 1 part resorcinol, 3.5 parts zinc methacrylate, 3 parts adhesive, 5 parts insoluble sulfur, and 1.4 parts accelerator;

[0103] The difference from Comparative Example 1 is that 30 parts of the natural rubber were replaced with epoxy natural rubber, and zinc methacrylate was added.

[0104] Other raw material requirements are the same as in Example 1.

[0105] The preparation method can be adjusted appropriately based on the raw materials, including:

[0106] S1. This step is the same as step S1 in Example 1. At the end of the step, a piece of adhesive is obtained.

[0107] S2. This step is the same as step S1 of Comparative Example 1, except that: the first-stage rubber of this comparative example is used instead of the natural rubber of Comparative Example 1, and a second-stage rubber is obtained after the step is completed.

[0108] S3. This step is the same as step S2 of Comparative Example 1, except that the two-stage glue of this comparative example is used instead of the one-stage glue of Comparative Example 1. After the step is completed, a three-stage glue is obtained.

[0109] S4. This step is the same as step S3 of Comparative Example 1, except that the three-stage glue of this comparative example is used instead of the two-stage glue of Comparative Example 1, and a four-stage glue is obtained after the step.

[0110] S5. This step is the same as step S4 of Comparative Example 1, except that the four-stage rubber of this comparative example is used instead of the three-stage rubber of Comparative Example 1, and zinc methacrylate is added. After the step is completed, the final rubber is obtained.

[0111] Preparation Example 1

[0112] This preparation example provides an airtight layer rubber for testing the adhesive properties of the tire transition layer rubbers provided in the various embodiments and comparative examples.

[0113] The airtight layer rubber comprises the following components in parts by weight: 100 parts brominated butyl rubber, 65 parts carbon black, 4 parts zinc oxide, 2 parts stearic acid, 0.5 parts insoluble sulfur, 2 parts accelerator, 8 parts hydrocarbon resin mixture, 0.6 parts magnesium oxide, and 7 parts naphthenic oil.

[0114] Among them, carbon black N660 was selected.

[0115] Performance testing

[0116] Performance testing includes: adhesive strength testing, tensile property testing, and wire pull-out force testing before aging and after aging at 96h*80℃.

[0117] The method for testing adhesion strength includes the following steps.

[0118] (1) Sample preparation: Select two pieces of steel cord fabric with a width of 25 mm and a length of 25 cm, and use them as skeleton materials. Wrap the tire transition layer rubber sheet obtained in each embodiment or comparative example and the airtight layer sheet obtained in Preparation Example 1 evenly on the surface of the two pieces of steel cord fabric with a thickness of 1 mm. Lay the two wrapped steel cord fabric pieces together, and place a piece of cellophane with a length of 5 cm and a width of 10 cm at the bonding interface from one end of the cord fabric towards the center of the area to form a sample. The cellophane is used to ensure that a 5 cm isolation area is formed at one end of the sample after vulcanization, and a 20 cm bonding area is formed at the other end. The tire transition layer rubber sheet material is selected from one of the above embodiments and comparative examples, and the airtight layer sheet material is the material prepared in Preparation Example 1.

[0119] (2) Vulcanization treatment: The prepared sample is placed in a flat vulcanizing machine for vulcanization. The vulcanization pressure is set to 8~10 bar and the vulcanization conditions are 150℃ for 60 min. After vulcanization, the sample is left to stand for 8 hours to allow the internal stress to be fully released and the performance to be stabilized, and the test sample is obtained.

[0120] (3) Performance test: The two steel wire cord film sheets of the test sample before or after aging are installed on the upper and lower clamps of the high-speed rail tensile testing machine (model AI-7000S). The tensile speed is set to 50mm / min. The equipment is started and the upper clamp is stretched upward to a position of 10cm. The average force value during the stretching process is recorded. This force value is the interlayer bonding force between the transition layer and the airtight layer.

[0121] Tensile properties were tested according to GB / T528-2009 "Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber".

[0122] The steel wire pull-out force test was conducted according to GB / T3513-2018 "Determination of Adhesion Force between Vulcanized Rubber and Single Steel Wire - Pull-out Method".

[0123] The test results are shown in Table 1.

[0124] Table 1

[0125]

[0126] Among them, the measured value of interlayer adhesion force before aging in Comparative Example 1 was 120N, and the measured value of interlayer adhesion force in Example 1 was 193, which is 161% of that in Comparative Example 1; the measured value of interlayer adhesion force after aging in Comparative Example 1 was 80N, and the measured value of interlayer adhesion force in Example 1 was 156, which is 158% of that in Comparative Example 1. Interlayer adhesion force is directly related to tire delamination problem. Therefore, the solution of the present invention can effectively solve the delamination problem and improve the overall performance and safety reliability of the tire.

[0127] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A rubber for a tire transition layer, characterized in that it comprises: The composition comprises the following components in parts by weight: 50-90 parts natural rubber, 10-50 parts epoxidized natural rubber, 13.5-18 parts carbon black, 31.5-42 parts silica, 3.15-4.2 parts silane coupling agent, 5-10 parts zinc oxide, 1.5-3.5 parts antioxidant, 0.3-1.2 parts cobalt borylate, 0.5-1.5 parts stearic acid, 0.5-2 parts resorcinol, 2-10 parts zinc methacrylate, 3-5 parts binder, 4.5-6 parts insoluble sulfur, and 1.3-2.5 parts accelerator; wherein the sum of the natural rubber and epoxidized natural rubber components is equal to 100 parts, and the mass ratio of silica to carbon black is (6-8):(2-4).

2. The rubber for tire transition layers as described in claim 1, characterized in that, The natural rubber is grade STR20; or the epoxidized natural rubber has an epoxidation degree of 10% to 20%.

3. The rubber for the tire transition layer as described in claim 2, characterized in that, The epoxidized natural rubber was selected as ENR10 with an epoxidation degree of 10%.

4. The rubber for the tire transition layer as described in claim 1, characterized in that, The carbon black is selected from one or more of N326, N375 and N330; Alternatively, the specific surface area of ​​the silica is 165±15m². 2 / g; or, the silane coupling agent is selected from one or both of Si-69 and Si-75.

5. The rubber for tire transition layers as described in claim 1, characterized in that, The specific surface area of ​​the zinc oxide is 8.0 ± 1.0 m². 2 / g; Alternatively, the antioxidant is selected from one or more of antioxidant 6PPD, antioxidant DTPD, and antioxidant 4010NA; Alternatively, the stearic acid has the following properties: iodine value ≤ 8.0 g / 100 g, acid value 196–211 mg / g, freezing point 52–60 °C, saponification index 197–212 mg KOH / g, C 18 and C 16 The total content of these components is ≥88wt%.

6. The rubber for tire transition layers as described in claim 1, characterized in that, The adhesive is selected from one or both of adhesives RA65 and HMT; Alternatively, the insoluble sulfur may be selected as OT20; Alternatively, the accelerator may be selected from one or more of accelerators DZ, accelerators NS and CZ.

7. A method for preparing rubber for a tire transition layer as described in any one of claims 1-6, characterized in that, Includes the following steps: S1. Mix natural rubber and epoxidized natural rubber, and knead at 135~165℃ to obtain primary rubber M1, and then cool. S2. Mix the first-stage rubber M1, silica, carbon black, silane coupling agent, zinc oxide, antioxidant and stearic acid, and knead at 142~158℃ to obtain the second-stage rubber M2, and then cool. S3. Mix the two-stage adhesive M2, cobalt borate and resorcinol, and knead at 135~145℃ to obtain the three-stage adhesive M3, and then cool. S4. Mix the three-stage adhesive M3 and the binder, and knead at 105~115℃ to obtain the four-stage adhesive M4, and then cool. S5. Mix the four-stage rubber M4, zinc methacrylate, insoluble sulfur and accelerator, and knead at 95~105℃ to obtain the rubber for the tire transition layer.

8. The method for preparing rubber for tire transition layers as described in claim 7, characterized in that, In S1~S4, the cooling methods include: tableting and cooling for 8 hours.

9. The method for preparing rubber for tire transition layers as described in claim 7, characterized in that, In S1, the internal mixer speed is 40~50 rpm, and the pressure of the top plug is 0.55~0.60 MPa; Alternatively, in S2, the internal mixer speed is 20~50 rpm, and the top plug pressure is 0.55~0.60 MPa; Alternatively, in S3, the internal mixer speed is 35~40 rpm, and the top plug pressure is 0.55~0.60 MPa; Alternatively, in S4, the internal mixer speed is 16~22 rpm, and the top plug pressure is 0.45~0.50 MPa; Alternatively, in S5, the internal mixer speed is 15~25 rpm, and the top plug pressure is 0.45~0.50 MPa.

10. An application of a rubber for a tire transition layer as described in any one of claims 1-6, characterized in that, Used for bonding the airtight layer and the carcass ply.

11. The application of the rubber for the tire transition layer as described in claim 10, characterized in that, The airtight layer comprises brominated butyl rubber, and the carcass ply comprises natural rubber.

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