A flexing-resistant rubber composition for a v-belt compression layer and a method of manufacturing the same

Abstract

The application discloses a kind of for triangle band compression layer flexing-resistant rubber composition and preparation method thereof.The flexing-resistant rubber composition weight part composition includes: natural rubber 70~80 parts, styrene butadiene rubber 20~25 parts, liquid polyisoprene rubber 10~15 parts, layered inorganic powder 20~25 parts, maleic anhydride polybutadiene 1~2 parts, blue cotton short fiber 5~10 parts, carbon black 50~60 parts, white carbon black 5~10 parts, coupling agent 3~5 parts, tackifier 2~4 parts, plasticizer 2~3 parts, activator 6~8 parts, antioxidant 1.5~2.0 parts, zinc methacrylate 0.5~1 part, accelerator 1~2 parts, sulfur 2.8~3.0 parts.Liquid polyisoprene rubber is used to mechanically shear modification layered inorganic powder, and it has layered slip property when being used in rubber composition, which avoids stress concentration.Collaborate blue cotton short fiber to increase strength, limit rubber molecular chain movement, prevent crack propagation, and improve flexing resistance.

Description

Technical Field

[0001] This invention relates to the field of functional rubber composition technology, and more specifically to a flexurally resistant rubber composition for the compression layer of a V-belt and its preparation method. Background Technology

[0002] A V-belt (also known as a triangular belt) is a trapezoidal cross-section ring-shaped transmission belt composed of a tension layer, a tensile core, a compression layer, and a fabric covering. The transmission efficiency and service life of a V-belt are its most critical technical indicators. To improve transmission efficiency, V-belts have gradually evolved towards narrower widths, thus placing higher demands on the performance of the compression layer rubber compound and the tensile core wire material.

[0003] The core strands of V-belts were initially made of cotton or nylon fiber, but these had limited lifespans due to low tensile strength, easy elongation, and poor fatigue resistance. Currently, the core strands are being upgraded to polyester-reinforced hemp fibers, which offer longer service life and higher tensile strength. The use of polyester-reinforced hemp fibers has significantly increased the lifespan of V-belts, reducing replacement frequency and maintenance costs. The compression layer of the V-belt is located at the bottom of the belt body, contacting the pulley and enduring cyclic bending and compression deformation. Therefore, higher requirements are placed on the flexural fatigue resistance and compression set resistance of the matching compression layer rubber compound.

[0004] Currently, compression layer rubber compounds are mainly based on natural and synthetic rubbers, with fillers such as carbon black used to enhance rubber stiffness. High stiffness leads to increased hardness, resulting in a high elastic modulus when used in compression layer rubbers. Under repeated deformation, this makes the rubber prone to stress concentration and low flexural fatigue resistance. According to currently available technologies, trans-1,4-polyisoprene (TPI) can effectively improve the flexural resistance of rubber. TPI molecular chains have a high degree of order, existing and crystallizing in a folded chain form at room temperature, imparting high hardness and tensile strength to the material. As temperature increases, the flexibility of the molecular chains increases. Through combination with other rubbers, the formed microcrystals act as physical cross-linking points, and vulcanization cross-links them into elastomers, thereby inhibiting crack initiation and propagation and improving the fatigue life of the rubber. For example, patent document CN107177057B discloses a rubber composition and its preparation method for manufacturing the compression layer of a wrapped V-belt. It uses a composite of natural rubber, styrene-butadiene rubber, and eucommia rubber, and utilizes eucommia rubber (trans-1,4-polyisoprene) to increase the flexural fatigue life of a Class 6 tear to 27,000 cycles. Patent document CN109942910B discloses a high flexural fatigue life aircraft tire sidewall rubber, which, through the use of trans-1,4-butadiene-isoprene copolymer rubber TBIR, achieves a flexural fatigue life of over 85,000 cycles against a Class 6 tear.

[0005] For V-belts subjected to long-term cyclic dynamic compression and bending, the compression layer compound must possess sufficient hardness and flexural strength to withstand frequent compression and bending, requiring a flexural cycle life of over 100,000 times for a grade 6 crack. When using trans-1,4-polyisoprene to increase flexural strength, the formation and dispersion of microcrystals are critical; the formation of large microcrystals can lead to excessive internal stress and cracking. Summary of the Invention

[0006] To adapt to the development of narrower V-belts and further improve the flexural strength of the compression layer rubber compound under repeated compressive stress, effectively preventing the formation and propagation of microcracks that lead to V-belt failure, this invention proposes a flexurally resistant rubber composition for the compression layer of V-belts and its preparation method. By modifying layered inorganic materials with liquid polyisoprene rubber, the microscopic flexibility and slippage of the modified layered inorganic materials in the rubber composition reduce stress concentration. Combined with the use of blue cotton short fibers, crack propagation is reduced, significantly improving the flexural strength of the compression layer rubber compound and extending the service life of the V-belt.

[0007] The above technical effects are achieved through the following technical solution:

[0008] First, the present invention provides a flexurally resistant rubber composition for the compression layer of a V-belt. The raw materials of the flexurally resistant rubber composition are composed of the following parts by weight: 70-80 parts of natural rubber, 20-25 parts of styrene-butadiene rubber, 10-15 parts of liquid polyisoprene rubber, 20-25 parts of layered inorganic powder, 1-2 parts of maleic anhydride-modified polybutadiene, 5-10 parts of blue cotton staple fiber, 50-60 parts of carbon black, 5-10 parts of silica, 3-5 parts of coupling agent, 2-4 parts of tackifier, 2-3 parts of plasticizer, 6-8 parts of activator, 1.5-2.0 parts of antioxidant, 0.5-1 part of zinc methacrylate, 1-2 parts of accelerator, and 2.8-3.0 parts of sulfur.

[0009] The liquid polyisoprene rubber has a weight-average molecular weight of 10,000 to 50,000, a cis-1,4-polyisoprene content of ≥70%, and a viscosity of 10 to 100 Pa·s at 60°C.

[0010] The layered inorganic powder is at least one of molybdenum disulfide and mica powder, and its D50 median particle size distribution is 5~10μm;

[0011] The length of the blue cotton staple fiber is 3~6mm;

[0012] The carbon black is a combination of N330 and N550 in a mass ratio of 1:2.

[0013] Preferably, the natural rubber is selected from smoked sheet rubber with an RSS3 grade or higher. The σ bonds adjacent to the double bonds on the natural rubber molecular chain are easily rotated, resulting in low steric hindrance and high flexibility. It can quickly recover its original shape after being deformed under stress, withstand frequent pressure and deformation, and exhibits excellent flexural resistance under high strain.

[0014] Preferably, the styrene-butadiene rubber is SBR1502 type styrene-butadiene rubber. SBR1502 type styrene-butadiene rubber has good tensile strength, abrasion resistance, and excellent flexural resistance under low strain.

[0015] By combining natural rubber and styrene-butadiene rubber as base materials, and matching the flexural properties at high and low strain, the basic flexural properties of the compression layer compound are constructed, exhibiting high toughness at high compressive strength.

[0016] Blue cotton staple fiber can significantly improve the strength of rubber materials, restrict the movement of rubber molecular chains, prevent the growth of flexural fatigue cracks, and enhance fatigue resistance.

[0017] The N330 carbon black used has a smaller particle size, which significantly improves the hardness, tensile strength, and abrasion resistance of the rubber compound; the N550 carbon black has a larger particle size, is easier to disperse, and significantly improves the heat resistance, resilience, and flexural strength of the rubber compound, effectively reducing compression set. By combining carbon black with different particle sizes, both the hardness and resilience of the rubber composition are considered.

[0018] Preferably, the coupling agent is at least one of 3-(methacryloyloxy)propyltrimethoxysilane, 3-aminopropyltriethoxysilane, and γ-glycidoxypropyltrimethoxysilane. Carbon black and silica fillers can improve the strength of rubber compositions, but uneven dispersion can create numerous stress concentration points, accelerating crack propagation. By pretreating fillers with coupling agents, the interfacial bonding and dispersibility between the filler and rubber are increased, stress concentration points caused by filler impurities are avoided, and the crack propagation resistance of the rubber compound is improved.

[0019] Preferably, the tackifier is one of coumarone resin or phenolic tackifying resin. The tackifier increases the viscosity of the rubber composition by forming physical crosslinks with rubber molecules through polar groups in its molecular chain.

[0020] Preferably, the plasticizer is one of naphthenic oil, aromatic oil, polyethylene wax, or pine tar.

[0021] Preferably, the activator is a combination of zinc oxide and stearic acid in a mass ratio of 2:1. Using a combination of zinc oxide and stearic acid, along with an accelerator, can significantly improve vulcanization efficiency, shorten vulcanization time, and enhance crosslinking density, thereby optimizing the physical and mechanical properties of the vulcanized rubber and enhancing its tear resistance, strength, elasticity, abrasion resistance, and hardness.

[0022] Zinc methacrylate acts as a co-crosslinking agent in the vulcanization process of rubber compositions, improving high and low temperature performance, tear resistance, and reducing compression set.

[0023] Preferably, the antioxidant is at least one of antioxidant ODA, antioxidant BLE-W, antioxidant 4020, and antioxidant 4010NA. It is used to delay the aging of rubber, especially showing significant inhibitory effects on ozone aging, thermal aging, and fatigue aging of rubber.

[0024] Preferably, the accelerator is at least one of accelerator DM, accelerator CZ, accelerator NOBS, and accelerator TBBS.

[0025] The present invention also provides a method for preparing a flexurally resistant rubber composition for a compression layer of a V-belt, characterized in that the specific preparation method is as follows:

[0026] S1. Modified layered inorganic material: 10-15 parts of liquid polyisoprene rubber, 20-25 parts of layered inorganic powder, and 1-2 parts of maleic anhydride-modified polybutadiene are ground and sheared 3-5 times in a three-roll mill to obtain the modified layered inorganic material.

[0027] S2. Modified filler: 50-60 parts of carbon black, 5-10 parts of silica, 3-5 parts of coupling agent, and 2-3 parts of plasticizer are dispersed and modified in a high-speed mixer to obtain the modified filler;

[0028] S3. Mixing the first stage rubber: Add 70-80 parts of natural rubber and 20-25 parts of styrene-butadiene rubber to a mixer and mix for 2-3 minutes; then add 2-4 parts of tackifier, 6-8 parts of activator, 1.5-2.0 parts of antioxidant, and 0.5-1 parts of zinc methacrylate and mix for 5-8 minutes; add the modified layered inorganic material from step S1, the modified filler from S2, and 5-10 parts of blue cotton staple fiber and mix for 3-5 minutes. Transfer the rubber compound to a two-roll mill, adjust the roll gap of the two-roll mill to 3 mm, and the roll temperature to 60-80℃. When the rubber compound forms a continuous roll wrap, sheet it to obtain the first stage rubber.

[0029] S4. Mixing the two-stage rubber: Let the first-stage rubber stand for 4-8 hours, add it to the open mill, adjust the roller gap of the open mill to 3 mm, the roller temperature to 60-80℃, add 1-2 parts of accelerator and 2.8-3.0 parts of sulfur, and roll it in a triangular shape 2-3 times; adjust the roller gap to 1 mm, and pass the rubber through the sheet twice; adjust the roller gap to 3 mm, and sheet it to obtain the second-stage rubber, which is a flexural rubber composition for the compression layer of V-belts.

[0030] By utilizing the dispersibility and flexibility of liquid polyisoprene rubber, layered inorganic powders can be modified under mechanical shearing. This can increase the flexibility and lamellar sliding properties of the layered inorganic powders. When used in rubber compositions, the microscopic flexibility and lamellar sliding properties of the modified layered inorganic materials can significantly alleviate stress concentration and inhibit cracking in the rubber compositions.

[0031] Preferably, the temperature of the three-roll mill in step S1 is 60~90℃. The low-viscosity liquid polyisoprene rubber and the layered inorganic powder are fully penetrated and modified under the extrusion and friction of the three-roll mill and the action of the maleic anhydride-modified polybutadiene compatibilizer.

[0032] Preferably, in step S2, the high-speed mixer rotates at 400~700 rpm and disperses at high speed for 15~20 min.

[0033] Preferably, after the first stage of rubber mixing is completed, the mixture is left to stand for 6 hours before mixing the second stage of rubber to relax the rubber molecular chains, restore their fatigue, and increase the plasticizing effect of the second stage mixing.

[0034] The use of blue cotton short fibers enables the rubber composition to achieve high strength and hardness during vulcanization, maintain structural integrity, inhibit fatigue crack propagation, and withstand frequent compressive stress and bending.

[0035] In summary, the advantages and beneficial effects of the present invention are as follows:

[0036] (1) The key to the flexural rubber composition of the present invention is to pre-shear and modify the layered inorganic material with liquid polyisoprene rubber, so that the liquid polyisoprene rubber component penetrates the layered inorganic material, giving the layered inorganic material a certain mechanical flexibility and slip toughness. The modified layered inorganic material slips in the rubber composition to reduce stress concentration caused by frequent compression, reduce the generation and propagation of cracks, thereby improving flexural resistance.

[0037] (2) The present invention uses flexible blue cotton short fibers to make the rubber composition vulcanized with high strength and hardness, maintain structural integrity, inhibit fatigue crack propagation, and withstand frequent compressive stress and bending.

[0038] (3) The present invention utilizes modified layered inorganic materials to maintain the flexibility of the rubber compound at the micro level and avoid stress concentration; and utilizes blue cotton short fibers to maintain the strength and hardness of the rubber compound at the macro level. The resulting rubber composition restricts the movement of molecular chains after vulcanization, prevents crack propagation, improves dynamic fatigue performance, and thus improves flexural properties.

[0039] (4) The rubber composition of the present invention has a simple preparation process, the raw materials are readily available, and it is suitable for large-scale production. Detailed Implementation

[0040] The present invention will now be described in detail to enable those skilled in the art to understand the specific technical solutions. The following embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. All other embodiments obtained by those skilled in the art based on the described embodiments without inventive effort are within the scope of protection of the present invention.

[0041] Unless otherwise specified, the raw materials and equipment used in this invention are all conventional materials and equipment in this technical field. Unless otherwise specified, the raw materials referred to are all conventionally used in this field and can be purchased commercially. The raw materials used in each embodiment and comparative example are shown in Table 1.

[0042] Table 1: Raw material types and suppliers used in the examples and comparative examples

[0043]

[0044] Example 1

[0045] S1. Modified layered inorganic material: Adjust the temperature of the three-roll mill to 70℃, grind and shear 15 parts of liquid polyisoprene rubber, 25 parts of mica powder and 2 parts of maleic anhydride-modified polybutadiene 5 times in the three-roll mill to obtain the modified layered inorganic material.

[0046] S2. Modified filler: 55 parts of carbon black, 8 parts of silica, 5 parts of coupling agent 3-aminopropyltriethoxysilane, and 3 parts of plasticizer naphthenic oil are dispersed in a high-speed mixer at 700 rpm for 15 min to obtain the modified filler; the carbon black is N330 and N550 combined in a mass ratio of 1:2.

[0047] S3. Mixing the first stage rubber: Add 75 parts of natural rubber and 25 parts of styrene-butadiene rubber to a mixer and mix for 3 minutes; then add 3 parts of coumarone resin, 6 parts of activator, 1 part of antioxidant ODA, 0.5 parts of antioxidant 4010NA, and 0.5 parts of zinc methacrylate and mix for 8 minutes, controlling the upper limit temperature of the mixer to 110℃; add the modified layered inorganic material from step S1, the modified filler from S2, and 8 parts of blue cotton staple fiber and mix for 5 minutes; put the rubber compound into an open mill, adjust the roller gap of the open mill to 3 mm, and the roller temperature to 70℃; when the rubber compound forms a continuous roll wrap, sheet it to obtain the first stage rubber; the activator is a combination of zinc oxide and stearic acid in a mass ratio of 2:1;

[0048] S4. Mixing the two-stage rubber: Let the first-stage rubber stand for 6 hours, add it to the open mill, adjust the roller gap of the open mill to 3 mm, the roller temperature to 70℃, add 0.5 parts of accelerator CZ, 1.2 parts of accelerator TBBS, and 2.8 parts of sulfur, and roll it into a triangular shape and turn it over 3 times; adjust the roller gap to 1 mm, and pass the rubber through the sheet twice; adjust the roller gap to 3 mm, and sheet it to obtain the second-stage rubber, which is a flexural rubber composition for the compression layer of V-belts.

[0049] Example 2

[0050] S1. Modified layered inorganic material: Adjust the temperature of the three-roll mill to 70℃, grind and shear 15 parts of liquid polyisoprene rubber, 20 parts of molybdenum disulfide, and 2 parts of maleic anhydride-modified polybutadiene 5 times in the three-roll mill to obtain the modified layered inorganic material.

[0051] S2. Modified filler: 50 parts of carbon black, 5 parts of silica, 4 parts of coupling agent 3-(methacryloyloxy)propyltrimethoxysilane, and 3 parts of plasticizer polyethylene wax are dispersed in a high-speed mixer at 700 rpm for 20 min to obtain the modified filler; the carbon black is N330 and N550 combined in a mass ratio of 1:2.

[0052] S3. Mixing the first stage rubber: Add 80 parts of natural rubber and 20 parts of styrene-butadiene rubber to a mixer and mix for 3 minutes; then add 4 parts of coumarone resin, 8 parts of activator, 1.8 parts of antioxidant BLE-W, and 1 part of zinc methacrylate and mix for 6 minutes, controlling the upper limit temperature of the mixer to 110℃; add the modified layered inorganic material from step S1, the modified filler from S2, and 10 parts of blue cotton staple fiber and mix for 5 minutes. Transfer the rubber compound to an open mill, adjust the roller gap of the open mill to 3 mm, and the roller temperature to 70℃. When the rubber compound forms a continuous roll wrap, sheet it to obtain the first stage rubber; the activator is a combination of zinc oxide and stearic acid in a mass ratio of 2:1.

[0053] S4. Mixing the two-stage rubber: Let the first-stage rubber stand for 8 hours, add it to the open mill, adjust the roller gap of the open mill to 3 mm, the roller temperature to 70℃, add 1 part of accelerator DM, 0.5 parts of accelerator CZ, and 3.0 parts of sulfur, and roll it over twice in a triangular shape; adjust the roller gap to 1 mm, and pass the rubber through the sheet twice; adjust the roller gap to 3 mm, and sheet it to obtain the second-stage rubber, which is a flexural rubber composition for the compression layer of V-belts.

[0054] Example 3

[0055] S1. Modified layered inorganic material: Adjust the temperature of the three-roll mill to 70℃, grind and shear 10 parts of liquid polyisoprene rubber, 20 parts of mica powder, and 1.5 parts of maleic anhydride-modified polybutadiene 5 times in the three-roll mill to obtain the modified layered inorganic material.

[0056] S2. Modified filler: 60 parts of carbon black, 10 parts of silica, 5 parts of coupling agent γ-glycidyl etheroxypropyltrimethoxysilane, and 3 parts of plasticizer pine tar are dispersed in a high-speed mixer at 400 rpm for 20 min to obtain the modified filler; the carbon black is N330 and N550 combined in a mass ratio of 1:2.

[0057] S3. Mixing the first stage rubber: Add 80 parts of natural rubber and 20 parts of styrene-butadiene rubber to a mixer and mix for 3 minutes; then add 4 parts of phenolic tackifying resin, 6 parts of activator, 1 part of antioxidant ODA, 0.5 parts of antioxidant 4010NA, and 1 part of zinc methacrylate and mix for 5 minutes, controlling the upper limit temperature of the mixer to 110℃; add the modified layered inorganic material from step S1, the modified filler from S2, and 5 parts of blue cotton staple fiber and mix for 5 minutes; put the rubber compound into an open mill, adjust the roller gap of the open mill to 3 mm, and the roller temperature to 80℃; when the rubber compound forms a continuous roll wrap, sheet it to obtain the first stage rubber; the activator is a combination of zinc oxide and stearic acid in a mass ratio of 2:1;

[0058] S4. Mixing the two-stage rubber: Let the first-stage rubber stand for 4 hours, add it to the open mill, adjust the roller gap of the open mill to 3 mm, the roller temperature to 80℃, add 1 part of accelerator DM, 0.6 parts of accelerator NOBS, and 2.8 parts of sulfur, and roll it into a triangular shape and turn it over 3 times; adjust the roller gap to 1 mm, and pass the rubber through the sheet twice; adjust the roller gap to 3 mm, and sheet it to obtain the second-stage rubber, which is a flexural rubber composition for the compression layer of V-belts.

[0059] Comparative Example 1

[0060] When this scheme is implemented as in Example 1, no layered inorganic material modified with liquid polyisoprene rubber is used.

[0061] Comparative Example 2

[0062] When this scheme is implemented according to Example 1, the liquid polyisoprene rubber, layered inorganic powder, and plasticizer are directly added and used in step S3.

[0063] Comparative Example 3

[0064] When this solution is implemented as in Example 1, blue cotton staple fiber is not used.

[0065] Comparative Example 4

[0066] When this scheme is implemented according to Example 1, carbon black and silica are directly added in step 3 without using a coupling agent.

[0067] The flexural rubber compositions of Examples 1-3 and Comparative Examples 1-4 were plasticized into sheets using an open mill and left to stand for 16 hours. Then, they were vulcanized for 25 minutes at a controlled pressure of 0.9 MPa and a temperature of 150 °C using a flat vulcanizing machine. The resulting samples were then cut to obtain test specimens. The Shore A hardness, tear strength, compression set, and flexural resistance of the test specimens were measured.

[0068] (1) Shore A Hardness: The compression layer rubber is subjected to periodic compression when the V-belt is working. Sufficient hardness is required to maintain its shape and compressive friction. However, excessive hardness can easily lead to decreased elasticity, increased heat generation, and reduced flexural strength. The optimal hardness is maintained between 70-80 HA. The Shore A hardness was measured according to GB / T 531.1-2008. The test results are shown in Table 2.

[0069] (2) Tear strength: The tear strength of the right-angled specimens was tested using a tensile testing machine according to GB / T529-2008 at a test speed of 500 mm / min. The test results are shown in Table 2.

[0070] (3) Compression set: The compression set was tested according to GB / T 7759.1-2015. At 70℃, the compression set was 25% and the compression was continued for 24 hours. The compression set was then tested after unloading. The test results are shown in Table 2.

[0071] Table 2:

[0072]

[0073] (4) Flexural resistance: The test was conducted using a flexural fatigue testing machine in accordance with the test standard GB / T 13934-2006 (Demosia test). The test frequency was 5 Hz. After 5000 flexes, the machine was stopped and observed until pinholes appeared. The number of flexes that reached grade 1 cracking was recorded. Then, the flexing was continued in units of 5000 flexes. The machine was stopped and the crack level was observed and recorded. The number of flexes that reached grade 3 cracking was recorded. The process continued until the crack level reached grade 6. The number of flexes that reached grade 6 cracking was recorded. The results are shown in Table 3.

[0074] Table 3:

[0075]

[0076] Based on the test data above, as shown in Table 2, the rubber composition of this invention ensures reasonable hardness and low compression set, exhibits good rebound recovery under long-term compressive stress, effectively maintains the contact pressure between the belt and pulley, reduces transmission slippage and energy loss, and improves the efficiency and service life of the V-belt transmission, demonstrating excellent overall performance. According to the test data in Table 3, the presence of Grade 1 crack pinholes indicates a high number of flexural cycles. In particular, the flexural cycles for the expansion of crack pinholes from Grade 1 to Grade 3 and Grade 6 cracks are long. Further, the rubber composition of the compression layer of this invention uses pre-modified layered inorganic powder of liquid polyisoprene rubber. The layered inorganic material alleviates stress concentration and prevents crack formation through microscopic flexibility and slippage. The accompanying blue cotton short fibers increase the flexibility of the rubber compound, delaying molecular chain breakage during bending and compression, effectively resisting crack propagation under repeated bending deformation.

Claims

1. A flexurally resistant rubber composition for the compression layer of a V-belt, characterized in that, The flexural rubber composition comprises the following raw materials by weight: 70-80 parts natural rubber, 20-25 parts styrene-butadiene rubber, 10-15 parts liquid polyisoprene rubber, 20-25 parts layered inorganic powder, 1-2 parts maleic anhydride-modified polybutadiene, 5-10 parts blue cotton staple fiber, 50-60 parts carbon black, 5-10 parts silica, 3-5 parts coupling agent, 2-4 parts tackifier, 2-3 parts plasticizer, 6-8 parts activator, 1.5-2.0 parts antioxidant, 0.5-1 part zinc methacrylate, 1-2 parts accelerator, and 2.8-3.0 parts sulfur. The liquid polyisoprene rubber has a weight-average molecular weight of 10,000 to 50,000, a cis-1,4-polyisoprene content of ≥70%, and a viscosity of 10 to 100 Pa·s at 60°C. The layered inorganic powder is at least one of molybdenum disulfide and mica powder, and the median D50 particle size distribution is 5~10μm; The length of the blue cotton staple fiber is 3~6mm; The carbon black is a combination of N330 and N550 in a mass ratio of 1:2; The flexurally resistant rubber composition is prepared by the following method: S1. Modified layered inorganic material: 10-15 parts of liquid polyisoprene rubber, 20-25 parts of layered inorganic powder, and 1-2 parts of maleic anhydride-modified polybutadiene are ground and sheared 3-5 times in a three-roll mill to obtain the modified layered inorganic material. S2. Modified filler: 50-60 parts of carbon black, 5-10 parts of silica, 3-5 parts of coupling agent, and 2-3 parts of plasticizer are dispersed and modified in a high-speed mixer to obtain the modified filler; S3. Mixing the first stage rubber: Add 70-80 parts of natural rubber and 20-25 parts of styrene-butadiene rubber to a mixer and mix for 2-3 minutes; then add 2-4 parts of tackifier, 6-8 parts of activator, 1.5-2.0 parts of antioxidant, and 0.5-1 parts of zinc methacrylate and mix for 5-8 minutes; add the modified layered inorganic material from step S1, the modified filler from S2, and 5-10 parts of blue cotton staple fiber and mix for 3-5 minutes. Transfer the rubber compound to a two-roll mill, adjust the roll gap of the two-roll mill to 3 mm, and the roll temperature to 60-80℃. When the rubber compound forms a continuous roll wrap, sheet it to obtain the first stage rubber. S4. Mixing the two-stage rubber: Let the first-stage rubber stand for 4-8 hours, add it to the open mill, adjust the roller gap of the open mill to 3 mm, the roller temperature to 60-80℃, add 1-2 parts of accelerator and 2.8-3.0 parts of sulfur, and roll it in a triangular shape 2-3 times; adjust the roller gap to 1 mm, and pass the rubber through the sheet twice; adjust the roller gap to 3 mm, and sheet it to obtain the second-stage rubber, which is a flexural rubber composition for the compression layer of V-belts.

2. The flexurally resistant rubber composition for the compression layer of a V-belt according to claim 1, characterized in that, The natural rubber is selected from smoked sheet rubber with an RSS3 grade or higher.

3. The flexurally resistant rubber composition for the compression layer of a V-belt according to claim 1, characterized in that, The styrene-butadiene rubber is SBR1502 type styrene-butadiene rubber.

4. The flexurally resistant rubber composition for the compression layer of a V-belt according to claim 1, characterized in that, The coupling agent is at least one of 3-(methacryloyloxy)propyltrimethoxysilane, 3-aminopropyltriethoxysilane, and γ-glycidoxypropyltrimethoxysilane.

5. The flexurally resistant rubber composition for the compression layer of a V-belt according to claim 1, characterized in that, The tackifier is either coumarone resin or phenolic tackifying resin.

6. The flexurally resistant rubber composition for the compression layer of a V-belt according to claim 1, characterized in that, The plasticizer is one of naphthenic oil, aromatic oil, polyethylene wax, or pine tar.

7. The flexurally resistant rubber composition for the compression layer of a V-belt according to claim 1, characterized in that, The activator is a combination of zinc oxide and stearic acid in a mass ratio of 2:

1.

8. The flexurally resistant rubber composition for the compression layer of a V-belt according to claim 1, characterized in that, The antioxidant is at least one of antioxidant ODA, antioxidant BLE-W, antioxidant 4020, and antioxidant 4010NA.

9. The flexurally resistant rubber composition for the compression layer of a V-belt according to claim 1, characterized in that, The accelerator is at least one of accelerator DM, accelerator CZ, accelerator NOBS, and accelerator TBBS.

Images