Composite cord thread, preparation method thereof and application of composite cord thread in tire

Abstract

The invention discloses a composite cord thread and a preparation method and application thereof, and belongs to the technical field of tires. The composite cord thread comprises modified basalt fibers and flexible fibers. The modified basalt fiber is obtained by firstly pretreating basalt fiber with a silane coupling agent and then coating with a composite impregnant; in the composite impregnant, the mass ratio of the epoxy resin to the isocyanate is (2: 1)-(5: 1). The invention provides a composite cord which comprises modified basalt fibers and flexible fibers, the basalt fibers have excellent high temperature resistance, high breaking strength, high elastic modulus, high bearing capacity and small mechanical property attenuation at high temperature; the flexible fibers are added, so that the overall flexibility and flex fatigue performance of the cord thread are remarkably improved, and the bonding with rubber is enhanced by forming stronger interface bonding with the rubber, so that the stress is effectively buffered, and the strain coordination is improved.

Description

Technical Field

[0001] This invention belongs to the field of tire technology, and particularly relates to a composite cord, its preparation method, and its application. Background Technology

[0002] With the widespread application and popularization of new energy electric vehicles, the market has placed higher demands on the radial load-bearing capacity of tires. As the core structure that bears the radial load of the tire (such as the vehicle's own weight and load), the tire carcass ply bears more than 80% of the radial load. Its performance directly affects the tire's support and deformation control capabilities. Therefore, it must have both high tensile strength and low energy loss characteristics.

[0003] Currently, semi-steel radial tires generally use polyester fiber in their carcasses, which offers a relatively balanced overall performance. On one hand, polyester fiber possesses moderate and stable strength, with a breaking strength of approximately 8-10 cN / dtex. While lower than aramid's 20-25 cN / dtex, it is significantly higher than nylon 66's 5-7 cN / dtex, sufficient to meet the requirements of passenger car and light electric vehicle tires under normal loads (approximately 600-1000 kg per tire). On the other hand, high-modulus, low-shrinkage polyester has a high initial modulus, reaching 100-150 cN / dtex, approximately twice that of ordinary polyester and three to four times that of nylon. This results in less deformation under the same load, contributing to the stability of tire dimensions.

[0004] However, as mainstream tire manufacturers develop HL-grade tires (with load capacities exceeding those of traditional reinforced XL tires) for new energy vehicles, polyester fibers exhibit limitations in extreme tests. During high-speed and durability tests, early circumferential fracture often occurs in the bead region, leading to overall cord failure. Analysis indicates that stress concentration in this area during testing causes heat accumulation exceeding the heat resistance limit of the polyester fiber, thus triggering fracture. Although the theoretical melting point of polyester is 255-260℃, the internal temperature during testing did not reach this melting point. However, under continuous load and repeated flexing, stress and heat localized, leading to accelerated modulus decline, mechanical property degradation, and ultimately premature tire failure. Basic research on the heat resistance of polyester fibers reveals that after heat treatment (190℃ × 15 min), the strength of polyester fibers shows almost no loss, but the elongation at constant load is 190-200% of that at room temperature, indicating significant hysteresis loss and hindering radial energy conduction. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the technical problem to be solved by this invention is the insufficient load-bearing capacity and heat resistance of polyester fibers used in traditional tire materials. This invention proposes a composite cord with higher load-bearing capacity, better heat resistance, and lower elongation at constant heat load compared to polyester fibers, as well as its preparation method and application.

[0006] To solve the aforementioned technical problem, the technical solution adopted by the present invention is as follows: The present invention provides a composite cord comprising modified basalt fiber and flexible fiber; The modified basalt fiber is obtained by first pretreating the basalt fiber with a silane coupling agent and then coating it with a composite impregnation agent. In the composite impregnating agent, the mass ratio of epoxy resin to isocyanate is 2:1-5:1.

[0007] Preferably, the flexible fiber is nylon 66 fiber.

[0008] Preferably, the silane coupling agent is γ-aminopropyltriethoxysilane.

[0009] Preferably, the composite cord comprises 60-70 parts by weight of modified basalt fiber and 30-40 parts by weight of flexible fiber.

[0010] Preferably, the mass ratio of epoxy resin to isocyanate in the composite impregnating agent is 3:1-4:1. By weight, the composite cord comprises 63-67 parts modified basalt fiber and 33-37 parts flexible fiber.

[0011] In a second aspect, the present invention provides a method for preparing the above-mentioned composite cord, comprising a preparation step of modified basalt fiber and a fiber composite step. The preparation steps of the modified basalt fiber include: Basalt fibers are immersed in an aqueous solution of silane coupling agent at 25-50℃ for 8-15 minutes to obtain pretreated basalt fibers. The pretreated basalt fiber is immersed in a composite impregnation agent and soaked at 40-60℃ for 15-25 minutes to obtain modified basalt fiber. The basalt fiber has a single filament diameter of 7μm-13μm and a denier of 800D-1200D. The silane coupling agent aqueous solution has a mass fraction of 0.5%-3.0%, and the composite impregnating agent has a solid content of 15%-25%.

[0012] Preferably, the fiber composite step includes: The modified basalt fiber and flexible fiber are twisted to a twist of 90 T / 10cm-110 T / 10cm. The denier of the flexible fiber is 800D-1200D.

[0013] Preferably, the silane coupling agent aqueous solution has a mass fraction of 1.0%-2.0%, and the impregnating agent has a solid content of 18%-22%. The monofilament diameter of basalt fiber is 9μm-11μm, and the denier is 900D-1100D; The denier of the flexible fiber is 900D-1100D; Twist is 95 T / 10cm-105 T / 10cm.

[0014] In a third aspect, the present invention provides the application of the above-mentioned composite cord in the preparation of tire carcass ply.

[0015] In a fourth aspect, the present invention provides a tire comprising the aforementioned tire carcass ply.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention provides a composite cord comprising modified basalt fiber and flexible fiber. Basalt fiber possesses excellent high-temperature resistance, with a long-term service temperature up to 650℃, effectively resisting heat generated by friction and flexing at the tire bead. It also exhibits high tensile strength and high elastic modulus, strong load-bearing capacity, and minimal mechanical property degradation at high temperatures, which is beneficial for controlling heat-resistant elongation under constant load, reducing hysteresis loss, and promoting radial energy conduction, thus alleviating localized stress and heat concentration. However, basalt fiber has poor adhesion to rubber, and its high rigidity can lead to insufficient cord flexibility if used alone, exacerbating stress concentration during tire deformation. Therefore, this invention further modifies the surface of the basalt fiber to improve its adhesion to rubber. In addition, flexible fiber is added, which not only significantly improves the overall flexibility and flexural fatigue performance of the cord but also enhances adhesion to rubber through a stronger interfacial bond, thereby effectively buffering stress and improving strain compatibility. The two work together to achieve comprehensive performance of stable load bearing, fatigue resistance and uniform stress distribution at high temperatures, making it especially suitable for high-temperature and high-stress parts such as tire beads. Detailed Implementation

[0017] The technical solutions in specific embodiments of the present invention will be described in detail and completely below. Obviously, the described embodiments are only some specific implementations of the overall technical solution of the present invention, and not all implementations. Based on the overall concept of the present invention, all other embodiments obtained by those skilled in the art fall within the protection scope of the present invention.

[0018] This invention provides a composite cord comprising modified basalt fiber and flexible fiber; The modified basalt fiber is obtained by first pretreating the basalt fiber with a silane coupling agent and then coating it with a composite impregnation agent. In the composite impregnation agent, the mass ratio of epoxy resin to isocyanate is 2:1-5:1.

[0019] It should be noted that currently, semi-steel radial tires generally use polyester fiber in their carcasses, which offers relatively balanced overall performance. However, as mainstream tire manufacturers develop HL-rated tires with higher load capacities for new energy vehicles, polyester fiber exhibits limitations in extreme tests. In high-speed and durability tests, early circumferential fracture often occurs in the bead region, leading to overall cord failure. Basic research on the heat resistance of polyester fiber reveals that while heat treatment (190℃ × 15min) results in almost no loss of strength, the elongation at a given load is 190-200% of that at room temperature, indicating significant hysteresis loss and hindering radial energy transfer.

[0020] To address the aforementioned issues, this invention provides a composite cord comprising modified basalt fiber. Basalt fiber is an inorganic fiber produced by melting and drawing basalt, and its inherent properties are highly compatible with the requirements of semi-steel radial tire carcass materials. In the prior art, the application of basalt fiber in tires is mostly concentrated in the sidewalls or buffer layers of heavy-duty and engineering tires, with less application in semi-steel radial tires (especially in carcass cords).

[0021] Advantages of basalt fiber: ① Excellent high temperature resistance: Basalt fiber has a melting point of over 1500℃ and a long-term service temperature of up to 650℃, which is much higher than that of polyester fiber (temperature resistance is usually ≤150℃). It can solve the problem of material failure caused by heat concentration due to friction / bending at the joint.

[0022] ② Mechanical property compatibility: The tensile strength (3.5~4.8GPa) and elastic modulus (79~91GPa) are both superior to those of polyester fiber. It has strong load-bearing capacity at room temperature and small mechanical property decay at high temperature, which helps to control the increase of heat resistance constant load elongation. The hysteresis loss is relatively small compared with polyester fiber, which is more conducive to the conduction of radial energy and reduces the local concentration effect of stress and heat.

[0023] The superior properties of basalt fiber make it a viable alternative to polyester fiber in semi-steel radial tire carcasses. However, there are currently no publicly available documents or reports regarding the application of basalt fiber in semi-steel radial tire carcasses, due to both its inherent superior properties and the challenges in commercializing it. Firstly, the adhesion between basalt fiber and rubber is poor. To solve this problem, this invention first uses a silane coupling agent and a composite impregnating agent to modify the surface of the basalt fiber, which improves the H-adhesion pull-out force between the basalt fiber and rubber by more than 40% compared with the unmodified material, thus meeting the integrity requirements of the tire cord and rubber. Secondly, since basalt fiber has high rigidity (large modulus), if it is directly made into cord, it will lead to poor flexural strength of the carcass layer, which will aggravate the stress concentration at the ferrule. Therefore, this invention designs a modified basalt fiber-flexible fiber composite cord structure, in which the modified basalt fiber provides high temperature resistance and high strength; the flexible fiber reduces the overall rigidity and improves flexibility through spiral wrapping. The above technical solution also limits the mass ratio of epoxy resin to isocyanate in the composite impregnating agent to 2:1-5:1. The reason is that when the epoxy resin content is too high (>5:1), the impregnating layer is too rigid and the flexibility of the cord decreases (it is easy to break after 100,000 flexes); when the isocyanate content is too high (<2:1), the impregnating layer is easy to become brittle and the adhesive strength decreases by more than 20% after heat aging.

[0024] In a preferred embodiment, the flexible fiber is nylon 66 fiber.

[0025] It should be noted that although the thermal decomposition temperature of polyester fiber can reach about 350℃, the actual failure temperature of the tire supported by the fiber-rubber composite is much lower than 350℃ due to the long-term repeated friction between the fiber and rubber and the repeated flexing motion of the tire itself during the driving process. Therefore, under the working conditions of high-speed driving (the internal temperature of the tire can reach 150℃), there is a possibility of premature tire failure caused by fiber damage.

[0026] This invention incorporates nylon 66 fiber into basalt fiber. On the one hand, this avoids the weakness of polyester in terms of extreme high-temperature resistance. On the other hand, nylon 66 fiber has stronger chemical compatibility with rubber than polyester fiber. The amide groups of modified nylon 66 form hydrogen bonds / chemical crosslinks with rubber, and the bonding force is more than 1.8 times that of polyester fiber.

[0027] In a preferred embodiment, the silane coupling agent is γ-aminopropyltriethoxysilane.

[0028] The above technical solution specifies that the silane coupling agent is γ-aminopropyltriethoxysilane because the amino group of γ-aminopropyltriethoxysilane (KH-550) can form a stable chemical bond with the hydroxyl group on the surface of basalt fiber, and the other end can crosslink with the tire rubber matrix. At the same time, its hydrolysis rate is suitable for fiber modification process, and it can take into account the interfacial bonding strength, resistance to damp heat aging and mechanical stability of composite cord, which fully meets the core performance requirements of tire materials.

[0029] In a preferred embodiment, the composite cord comprises, by weight, 60-70 parts modified basalt fiber and 30-40 parts flexible fiber.

[0030] The above technical solution clarifies the dosage of modified basalt fiber and flexible fiber in the composite cord because: when the modified basalt fiber content is less than 60 parts, the high-temperature strength of the composite cord is insufficient; if its dosage is greater than 70 parts, the cord rigidity is too high, making it prone to breakage during flexural testing. On the other hand, if the proportion of flexible fiber is less than 30 parts, the improvement effect on the cord's flexural performance is not significant; while exceeding 40 parts leads to a decrease in the cord's room-temperature strength, with a breaking strength below 3.0 GPa. Therefore, by controlling both dosages within the above-mentioned range, the cord's high-temperature strength and dimensional stability can be maintained while optimizing its flexibility and durability, achieving a balanced performance match.

[0031] It is understood that the amount of modified basalt fiber can be 61, 62, 63, 64, 65, 66, 67, 68, or 69 parts or any value within the above-mentioned limits; the amount of flexible fiber can be 31, 32, 33, 34, 35, 36, 37, 38, or 39 parts or any value within the above-mentioned limits.

[0032] In a preferred embodiment, the mass ratio of epoxy resin to isocyanate in the composite impregnating agent is 3:1-4:1; By weight, the composite cord comprises 63-67 parts modified basalt fiber and 33-37 parts flexible fiber.

[0033] In a second aspect, the present invention provides a method for preparing the above-mentioned composite cord, comprising a preparation step of modified basalt fiber and a fiber composite step. The preparation steps of modified basalt fiber include: Basalt fibers are immersed in an aqueous solution of silane coupling agent at 25-50℃ for 8-15 minutes to obtain pretreated basalt fibers. The pretreated basalt fiber is immersed in a composite impregnation agent and soaked at 40-60℃ for 15-25 minutes to obtain modified basalt fiber. Among them, the monofilament diameter of basalt fiber is 7μm-13μm, and the denier is 800D-1200D; The mass fraction of the silane coupling agent aqueous solution is 0.5%-3.0%, and the solid content of the composite impregnating agent is 15%-25%.

[0034] The above technical solution limits the diameter of the monofilament of basalt fiber because when the diameter of the modified basalt fiber monofilament is less than 7μm, the monofilament is easy to break and the twisting process is difficult; when it is greater than 13μm, the fiber specific surface area is small and the contact with the composite impregnating agent is insufficient; within this diameter range, the monofilament breaking strength is stable at 3.5GPa-4.8GPa, which is suitable for the twisting process.

[0035] The above technical solution also limits the immersion time and temperature in the silane coupling agent aqueous solution. This is because when the immersion time is less than 8 minutes, the hydrolysis products of the coupling agent cannot fully react with the hydroxyl groups on the fiber surface; when the immersion time is more than 15 minutes, the coupling agent is prone to agglomeration, affecting the uniformity of interfacial bonding; immersion at 25-50℃ avoids the high temperature causing premature cross-linking of the hydrolysis products.

[0036] The above technical solution also limits the immersion time and temperature in the composite impregnating agent, because it can ensure that the impregnating agent fully wets the gaps on the fiber surface and forms a bonding layer of uniform thickness; immersion at 40-60℃ can improve the fluidity of the impregnating agent and promote secondary penetration of the pretreated fibers.

[0037] The above technical solution also limits the mass fraction of the silane coupling agent aqueous solution. This is because when the mass fraction of the silane coupling agent aqueous solution is less than 0.5%, the number of active groups on the fiber surface is insufficient, the modification effect is poor, and the H extraction adhesion is <70N / tex, which does not meet the tire requirements. When the mass fraction of the silane coupling agent aqueous solution is higher than 2.0%, the coupling agent is prone to agglomerate on the fiber surface, resulting in fiber adhesion and poor cord dispersion.

[0038] The above technical solution also limits the solid content of the composite impregnating agent. The reason is that when the solid content of the composite impregnating agent is less than 15%, the coating will be too thin and the adhesion will be insufficient; when the solid content of the composite impregnating agent is higher than 25%, the coating will be too thick and the cord diameter will exceed the standard. Within this range, the coating thickness is stable at 1.0μm-1.5μm and the cord diameter deviation is ≤±0.02mm. In a preferred embodiment, the fiber composite step includes: Modified basalt fiber and flexible fiber are twisted to a twist of 90 T / 10cm-110 T / 10cm. The denier of the flexible fiber is 800D-1200D.

[0039] The above technical solution also limits the denier of both basalt fiber and flexible fiber to 800D-1200D. The reason is that when the denier of both is below 800D, the cord load-bearing capacity is insufficient and cannot meet the tire carcass load requirements of HL-level tires; if it is above 1200D, the cord is too thick, the tire carcass thickness exceeds the standard, and it is not conducive to the tire lightweight requirements; within the range of 800D-1200D, the cord breaking strength is high, which meets the tire carcass load requirements of HL-level tires.

[0040] The above technical solution also limits the twist range of the composite cord. This is because when the twist is below 90T / 10cm, the cord structure is loose and easily dispersed under stress; when the twist is above 110T / 10cm, the stress inside the cord is concentrated and easily fatigue cracks occur during flexing; within the twist range of 90T / 10cm-110T / 10cm, the cord has a small elongation at constant load and the stress decay after 100,000 flexes is <10%.

[0041] In a preferred embodiment, the silane coupling agent aqueous solution has a mass fraction of 1.0%-2.0%, and the impregnating agent has a solid content of 18%-22%. The monofilament diameter of basalt fiber is 9μm-11μm, and the denier is 900D-1100D; The denier of the flexible fiber is 900D-1100D; Twist is 95 T / 10cm-105 T / 10cm.

[0042] In a third aspect, the present invention provides the application of the above-mentioned composite cord in the preparation of tire carcass ply.

[0043] In a preferred embodiment, the method for preparing the tire carcass ply includes the following steps: Heat setting treatment: The composite cord is heat set by a heat setting machine; RFL impregnation treatment: The heat-set composite cord is immersed in resorcinol-formaldehyde-latex impregnation solution (RFL), dried, and then heat-stretched and shaped to form an adhesive interface layer. Weaving and forming: After the sizing of the sizing cord is warped, it is woven into a cord fabric blank by a rapier loom; Post-processing and inspection: The fabric is heat-set to stabilize its width, and its appearance and physical properties are inspected. After passing the inspection, it is wound into rolls and shipped out.

[0044] In a fourth aspect, the present invention provides a tire comprising the aforementioned carcass ply.

[0045] To provide a clearer and more detailed description of the composite cord, its preparation method, and its applications provided in the embodiments of the present invention, the following description will be based on specific embodiments.

[0046] Example 1: Preparation of Composite Cord 1. Raw material composition (parts by weight): 60 parts modified basalt fiber and 40 parts nylon 66 fiber; 2. Preparation method: (1) Preparation of modified basalt fiber: Basalt fibers were immersed in a 0.5% (w / w) aqueous solution of silane coupling agent at 25°C for 8 minutes to obtain pretreated basalt fibers. The basalt fiber has a single filament diameter of 7μm and a denier of 800D. The pretreated basalt fibers were immersed in a composite impregnation agent with a solid content of 15%, wherein the mass ratio of epoxy resin to isocyanate in the composite impregnation agent was 5:1, the temperature was 40℃, and the immersion time was 15 minutes to obtain modified basalt fibers. (2) Fiber composite steps: Modified basalt fiber and nylon 66 fiber were twisted to a twist of 90 T / 10cm to obtain composite cord; Among them, the denier of nylon 66 fiber is 800D.

[0047] Example 2: Preparation of Composite Cord 1. Raw material composition (parts by weight): 65 parts modified basalt fiber and 35 parts nylon 66 fiber; 2. Preparation method: (1) Preparation of modified basalt fiber: Basalt fibers were immersed in a 1.8% (w / w) aqueous solution of silane coupling agent at 38°C for 12 minutes to obtain pretreated basalt fibers. The basalt fiber has a single filament diameter of 10 μm and a denier of 1000D. The pretreated basalt fibers were immersed in a composite impregnation agent with a solid content of 20%, wherein the mass ratio of epoxy resin to isocyanate in the composite impregnation agent was 3.5:1, the temperature was 42℃, and the immersion time was 20 minutes to obtain modified basalt fibers. (2) Fiber composite steps: Modified basalt fiber and nylon 66 fiber were twisted to a twist of 100T / 10cm to obtain composite cord; Among them, the denier of nylon 66 fiber is 1000D.

[0048] Example 3: Preparation of Composite Cord 1. Raw material composition (parts by weight): 70 parts modified basalt fiber and 30 parts nylon 66 fiber; 2. Preparation method: (1) Preparation of modified basalt fiber: Basalt fibers were immersed in a 3.0% (w / w) aqueous solution of silane coupling agent at 50°C for 15 minutes to obtain pretreated basalt fibers. Among them, the basalt fiber has a single filament diameter of 13 μm and a denier of 1200D; The pretreated basalt fibers were immersed in a composite impregnation agent with a solid content of 25%, wherein the mass ratio of epoxy resin to isocyanate in the composite impregnation agent was 2:1, the temperature was 60℃, and the immersion time was 25 minutes to obtain modified basalt fibers. (2) Fiber composite steps: Modified basalt fiber and nylon 66 fiber were twisted to a twist of 110 T / 10cm to obtain composite cord; Among them, the denier of nylon 66 fiber is 1200D.

[0049] Example 4: Preparation of tire carcass ply using composite cords prepared in Example 1 (1) Heat setting treatment: The composite cord prepared in Example 1 is subjected to a heat setting machine to eliminate internal stress and reduce heat shrinkage rate.

[0050] (2) RFL impregnation treatment: The heat-set composite cord is immersed in resorcinol-formaldehyde-latex impregnation solution (RFL) (solid content is 20%), dried and then heat-stretched and shaped. (3) Weaving and forming: After the sizing of the glued cord is warped, it is woven on a rapier loom with a twill weave and the warp density (30 threads / cm) and weft density (4 threads / cm) are controlled to form the cord fabric.

[0051] (4) Finishing and inspection: The fabric is heat-set to stabilize the width, and its appearance (no broken threads or skipped stitches) and physical properties (breaking strength, heat shrinkage rate, and adhesive strength) are inspected. After passing the inspection, it is wound into rolls and shipped out.

[0052] Example 5: Preparation of tire carcass ply using composite cords prepared in Example 2 (1) Heat setting treatment: The composite cord prepared in Example 2 is heat set by a heat setting machine to eliminate internal stress and reduce heat shrinkage rate.

[0053] (2) RFL impregnation treatment: The heat-set composite cord is immersed in resorcinol-formaldehyde-latex impregnation solution (RFL) (solid content is 20%), dried and then heat-stretched and shaped. (3) Weaving and forming: After the sizing of the glued cord is warped, it is woven on a rapier loom with a twill weave and the warp density (30 threads / cm) and weft density (4 threads / cm) are controlled to form the cord fabric.

[0054] (4) Finishing and inspection: The fabric is heat-set to stabilize the width, and its appearance (no broken threads or skipped stitches) and physical properties (breaking strength, heat shrinkage rate, and adhesive strength) are inspected. After passing the inspection, it is wound into rolls and shipped out.

[0055] Example 6: Preparation of tire carcass ply using composite cords prepared in Example 3 (1) Heat setting treatment: The composite cord prepared in Example 3 is heat set by a heat setting machine to eliminate internal stress and reduce heat shrinkage rate.

[0056] (2) RFL impregnation treatment: The heat-set composite cord is immersed in resorcinol-formaldehyde-latex impregnation solution (RFL) (solid content is 20%), dried and then heat-stretched and shaped. (3) Weaving and forming: After the sizing of the glued cord is warped, it is woven on a rapier loom with a twill weave and the warp density (30 threads / cm) and weft density (4 threads / cm) are controlled to form the cord fabric.

[0057] (4) Finishing and inspection: The fabric is heat-set to stabilize the width, and its appearance (no broken threads or skipped stitches) and physical properties (breaking strength, heat shrinkage rate, and adhesive strength) are inspected. After passing the inspection, it is wound into rolls and shipped out.

[0058] Comparative Example 1: Preparation of tire carcass ply using 100% polyester fiber cord 1. Preparation of 100% polyester fiber cord: 100% polyester fiber is obtained by melt spinning, stretching and orientation, and twisting (twist degree 100T / 10cm) polyester chips. 2. Preparation of tire carcass ply: (1) Heat setting treatment: 100% polyester fiber cords are heat set by a heat setting machine to eliminate internal stress and reduce heat shrinkage rate.

[0059] (2) RFL impregnation treatment: The heat-set composite cord is immersed in resorcinol-formaldehyde-latex impregnation solution (solid content is 20%) (RFL), dried, and then heat-stretched and shaped to form an adhesive interface layer to ensure the bonding strength with rubber.

[0060] (3) Weaving and shaping: After the sizing of the glued cord is warped, it is woven by a rapier loom with a twill weave and shaped into P 1000D / 2-25EPI (warp density is 100 threads / dm) to form the cord fabric.

[0061] (4) Finishing and inspection: The fabric is heated to stabilize the width (temperature 170℃), and its appearance (no broken threads or skipped stitches) and physical properties (breaking strength, heat shrinkage rate, and adhesive strength) are inspected. After passing the inspection, it is wound into rolls and shipped out.

[0062] Comparative Example 2: Preparation of tire carcass ply using modified basalt fiber 1. Preparation of modified basalt fibers: Basalt fibers were immersed in a 1.8% (w / w) aqueous solution of silane coupling agent at 38°C for 12 minutes to obtain pretreated basalt fibers. The basalt fiber has a single filament diameter of 10 μm and a denier of 1000D. The pretreated basalt fibers were immersed in a composite impregnation agent with a solid content of 20%, wherein the mass ratio of epoxy resin to isocyanate in the composite impregnation agent was 3.5:1, the temperature was 42℃, and the immersion time was 20 minutes to obtain modified basalt fibers. 2. Preparation of tire carcass ply: (1) Heat setting treatment: The modified basalt fiber is heat set by a heat setting machine to eliminate internal stress and reduce heat shrinkage rate.

[0063] (2) RFL impregnation treatment: The heat-set composite cord is immersed in resorcinol-formaldehyde-latex impregnation solution (RFL) (solid content is 20%), dried and then heat-stretched and shaped. (3) Weaving and shaping: After the sizing of the glued cord is warped, it is woven by a rapier loom with a twill weave and shaped as B 1000D / 2-25EPI (warp density is 100 threads / dm) to form the cord fabric.

[0064] (4) Finishing and inspection: The fabric is heat-set to stabilize the width, and its appearance (no broken threads or skipped stitches) and physical properties (breaking strength, heat shrinkage rate, and adhesive strength) are inspected. After passing the inspection, it is wound into rolls and shipped out.

[0065] Comparative Example 3: Preparation of tire carcass ply using nylon 66 fiber 1. Preparation of Nylon 66 fiber: Nylon 66 fibers were obtained by melt spinning, stretching and orientation, and twisting of nylon 66 chips at a twist of 100T / 10cm. 2. Preparation of tire carcass ply: (1) Heat setting treatment: Nylon 66 fibers are heat set by a heat setting machine to eliminate internal stress and reduce heat shrinkage rate.

[0066] (2) RFL impregnation treatment: The heat-set composite cord is immersed in resorcinol-formaldehyde-latex impregnation solution (RFL) (solid content is 20%), dried and then heat-stretched to form an adhesive interface layer to ensure the bonding strength with rubber.

[0067] (3) Weaving and shaping: After the sizing of the glued cord is warped, it is woven by a rapier loom with a twill weave and woven into N 1000D / 2-25EPI (warp density is 100 threads / dm) to form the cord fabric.

[0068] (4) Finishing and inspection: The fabric is heat-set to stabilize the width, and its appearance (no broken threads or skipped stitches) and physical properties (breaking strength, heat shrinkage rate, and adhesive strength) are inspected. After passing the inspection, it is wound into rolls and shipped out.

[0069] Application Example 1 Based on the existing tire model "235 / 45ZR18 98WXL EXTREME EV95 CROSSLEADER", a double-layer carcass ply design is adopted to replace the carcass ply of the tire. This application example is to replace the original tire carcass ply in tire 235 / 45ZR18 98WXLEXTREME EV95 CROSSLEADER with the tire carcass ply prepared in Example 4. Then, high-temperature vulcanization is carried out to obtain tires; The vulcanization temperature was 160℃, the total vulcanization time was 17.5 min, and the vulcanization pressure was 1.2 MPa.

[0070] Application Example 2 Based on the existing tire model "235 / 45ZR18 98WXL EXTREME EV95 CROSSLEADER", a double-layer carcass ply design is adopted to replace the carcass ply of the tire. This application example is to replace the original tire carcass ply in tire 235 / 45ZR18 98WXLEXTREME EV95 CROSSLEADER with the tire carcass ply prepared in Example 5. Then, high-temperature vulcanization is carried out to obtain tires; The vulcanization temperature was 165℃, the total vulcanization time was 18.5 min, and the vulcanization pressure was 1.5 MPa.

[0071] Application Example 3 Based on the existing tire model "235 / 45ZR18 98WXL EXTREME EV95 CROSSLEADER", a double-layer carcass ply design is adopted to replace the carcass ply of the tire. This application example is to replace the original tire carcass ply in tire 235 / 45ZR18 98WXLEXTREME EV95 CROSSLEADER with the tire carcass ply prepared in Example 6. Then, high-temperature vulcanization is carried out to obtain tires; The vulcanization temperature was 170℃, the total vulcanization time was 19.5 min, and the vulcanization pressure was 1.8 MPa.

[0072] Application Example 4 Based on the existing tire model "235 / 45ZR18 98WXL EXTREME EV95 CROSSLEADER", a double-layer carcass ply design is adopted to replace the carcass ply of the tire. The tire carcass ply prepared in Comparative Example 1 was used to replace the original tire carcass ply in tire 235 / 45ZR18 98WXL EXTREME EV95CROSSLEADER. Then, high-temperature vulcanization is carried out to obtain tires; The vulcanization temperature was 165℃, the total vulcanization time was 14.5 min, and the vulcanization pressure was 1.5 MPa.

[0073] Application Example 5 Based on the existing tire model "235 / 45ZR18 98WXL EXTREME EV95 CROSSLEADER", a double-layer carcass ply design is adopted to replace the carcass ply of the tire. The tire carcass ply prepared in Comparative Example 2 was used to replace the original tire carcass ply in tire 235 / 45ZR18 98WXL EXTREME EV95CROSSLEADER. Then, high-temperature vulcanization is carried out to obtain tires; The vulcanization temperature was 165℃, the total vulcanization time was 18.5 min, and the vulcanization pressure was 1.5 MPa.

[0074] Application Example 6 Based on the existing tire model "235 / 45ZR18 98WXL EXTREME EV95 CROSSLEADER", a double-layer carcass ply design is adopted to replace the carcass ply of the tire. The tire carcass ply prepared in Comparative Example 3 was used to replace the original tire carcass ply in tire 235 / 45ZR18 98WXL EXTREME EV95CROSSLEADER. Then, high-temperature vulcanization is carried out to obtain tires; The vulcanization temperature was 165℃, the total vulcanization time was 18.5 min, and the vulcanization pressure was 1.5 MPa.

[0075] Test case Performance tests were conducted on the tire carcass plies prepared in Examples 4-6, Comparative Examples 1-3, and the tires prepared in Examples 1-6. 1. Test method: 1.1 Pull-out force (N) after 1100℃×48h heat aging: The H-pull-out force of the tire carcass ply was tested using a universal electronic tensile testing machine in accordance with GB / T2942-2009.

[0076] 1.2 Increase in elongation at constant heat load (50N): The increase in elongation at a constant load (50N) of the tire carcass ply was tested in accordance with Part 7 of the national standard GB / T 19390-2023, which describes tensile properties. The elongation at constant load refers to the test performed after heat treatment at 190℃ for 15 minutes, followed by resting at room temperature, and compared with the elongation at constant load measured at room temperature. The increase represents the difference between the two, and the smaller the increase, the better.

[0077] The 50N constant load elongation is a test item in GB / T 19390-2023, meaning the deformation of the cord under a given load (50N). The test procedure is as follows: (This test item index is obtained through tensile testing). Status after 13.1 million cycles of flexion: The test was conducted in accordance with the national standard GB / T 30315-2013. After 100,000 flexes, the surface condition of the tire carcass ply was compared to determine which tire had relatively better flexural resistance.

[0078] 1.4 High-speed performance test: The high-speed performance of the tires was tested in accordance with the national standard GB / T 2928.

[0079] 1.5 Durability test: The durability of the tires shall be tested in accordance with the national standard GB / T 2928.

[0080] 2. Test Results: Table 1 Test results of tire carcass ply performance

[0081] As shown in Table 1, the tire carcass ply prepared using the composite cord prepared in this application has significantly improved heat resistance and significantly reduced elongation at constant load under heat resistance compared to the traditional polyester fiber carcass ply. No cracks were generated after 100,000 flexural tests.

[0082] Table 2 Tire performance test results

[0083] As shown in Table 2, the tires with carcass ply made using the composite cord of this application have significantly improved high-speed performance and durability.

Claims

1. A composite cord, characterized in that, The composite cord comprises modified basalt fiber and flexible fiber; The modified basalt fiber is obtained by first pretreating the basalt fiber with a silane coupling agent and then coating it with a composite impregnation agent. In the composite impregnating agent, the mass ratio of epoxy resin to isocyanate is 2:1-5:

1.

2. The composite cord according to claim 1, characterized in that, The flexible fiber is nylon 66 fiber.

3. The composite cord according to claim 2, characterized in that, The silane coupling agent is γ-aminopropyltriethoxysilane.

4. The composite cord according to claim 3, characterized in that, By weight, the composite cord comprises 60-70 parts modified basalt fiber and 30-40 parts flexible fiber.

5. The composite cord according to claim 4, characterized in that, In the composite impregnating agent, the mass ratio of epoxy resin to isocyanate is 3:1-4:1; By weight, the composite cord comprises 63-67 parts modified basalt fiber and 33-37 parts flexible fiber.

6. The method for preparing the composite cord according to any one of claims 1-5, characterized in that, This includes the preparation steps of modified basalt fibers and the fiber composite steps; The preparation steps of the modified basalt fiber include: Basalt fibers are immersed in an aqueous solution of silane coupling agent at 25-50℃ for 8-15 minutes to obtain pretreated basalt fibers. The pretreated basalt fiber is immersed in a composite impregnation agent and soaked at 40-60℃ for 15-25 minutes to obtain modified basalt fiber. The basalt fiber has a single filament diameter of 7μm-13μm and a denier of 800D-1200D. The silane coupling agent aqueous solution has a mass fraction of 0.5%-3.0%, and the composite impregnating agent has a solid content of 15%-25%.

7. The preparation method according to claim 6, characterized in that, The fiber composite step includes: The modified basalt fiber and flexible fiber are twisted to a twist of 90 T / 10cm-110 T / 10cm to obtain a composite cord. The denier of the flexible fiber is 800D-1200D.

8. The preparation method according to claim 7, characterized in that, The silane coupling agent aqueous solution has a mass fraction of 1.0%-2.0%, and the solid content of the impregnating agent is 18%-22%. The monofilament diameter of basalt fiber is 9μm-11μm, and the denier is 900D-1100D; The denier of the flexible fiber is 900D-1100D; Twist is 95 T / 10cm-105 T / 10cm.

9. The use of the composite cord according to any one of claims 1-5 in the preparation of tire carcass ply.

10. A tire, characterized in that, Includes the tire carcass ply as described in claim 9.

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