High-durability gradient reinforced composite material for aircraft tire and aircraft tire bead structure

Abstract

The invention discloses a high-durability gradient reinforced composite material for an aircraft tire and a tire bead structure of the aircraft tire. The Shore A hardness of the high-durability gradient reinforced composite material is 50-75 degrees, the 100%-300% stress at definite elongation is larger than or equal to 5 MPa, the tensile strength is larger than or equal to 20 MPa, and the elongation at break is larger than or equal to 450%. In the thickness direction, the high-durability gradient reinforced composite material has a hardness gradient and / or a modulus gradient. Tire bead reinforcing rubber is arranged between tire bead rubber and the rim edge of the tire bead structure of the aircraft tire, the tire bead reinforcing rubber adopts the high-durability gradient reinforced composite material, the hardness of the tire bead reinforcing rubber is gradually increased and / or the modulus is gradually increased in the direction from the tire bead rubber to the rim edge, the concentration phenomenon of dynamic strain is effectively reduced, the heat generation amount is reduced, and the service life of the tire bead structure is prolonged. Material aging and performance degradation caused by high temperature are avoided, the durability and fatigue resistance of the tire bead structure are remarkably improved, and the use requirements of aircraft tires under high-load and high-frequency strain working conditions are met.

Description

Technical Field

[0001] The present invention relates to the technical field of aircraft tires, and in particular to a high-durability gradient reinforced composite material for aircraft tires, an aircraft tire bead structure, and a molding method and application thereof. Background Art

[0002] Aircraft tires are the only parts of an aircraft that come into contact with the ground. They bear most of the load and impact during takeoff and landing. During use, tires roll frequently under heavy loads and high speeds, and the cyclic strain rate of the rubber material in the bead area increases significantly. Especially for radial aircraft tires, under high load and high-speed rolling conditions, the strain of the bead rubber is significantly higher than that of the shoulder. Due to the viscoelastic properties of rubber, strain lags behind stress, resulting in the conversion of hysteresis energy loss into heat. Therefore, the heat generated by the bead rubber of radial aircraft tires is much greater than that of other parts. The high temperature causes the performance of the rubber and cord in the bead area to decline rapidly, leading to failure problems.

[0003] In addition, when the tire is in use, the rubber layer close to the wheel rim is subject to a large compressive stress, which acts in the direction from the wheel rim to the center of the tire, while the rubber and cords of the carcass ply inside the bead are subject to tensile stress, which is in the direction of the cord arrangement, that is, from the bead to the sidewall. Therefore, there is a large difference in force between the rubber in the bead area and the rubber on the carcass ply, and a large shear stress is generated between the bead rubber layer and the carcass ply, which can easily lead to failure phenomena such as delamination and cracking of the bead rubber, seriously affecting the durability of the bead.

[0004] In order to improve the durability of radial aircraft tire beads and provide safety for aircraft, a reasonable bead structure design is urgently needed, which can not only reduce the shear stress between the rubber and the cord layer, but also effectively control the strain of the bead rubber, thereby significantly extending the service life of the tire and reducing maintenance costs.

[0005] Invention JPH09155884A discloses a tire molding method and tire that controls the temperature gradient of an unvulcanized tire through a vulcanizer mold. This technology forms a modulus gradient in the thickness direction of the tread rubber by different heating temperatures inside and outside. The modulus gradient gradually increases from the tread surface of the tread rubber in the thickness direction, and the modulus gradient corresponds to a rate of change within a range of 2% to 5% per 1mm of tread rubber thickness. However, this invention is mainly designed for the tread rubber of vehicle tires. The overall modulus of the tread rubber is relatively high, and its reference value and effect in the shear stress distribution and strain control of the bead area are low. In addition, this invention obtains the modulus gradient through the temperature gradient in tire molding, and its accuracy and controllability are relatively low, making it difficult to solve the problem of easy failure of the bead area of ​​aviation tires under high frequency and high pressure conditions.

[0006] Aiming at the durability design of the tire bead area, invention CN103010460B discloses a radial aviation tire capable of reducing interface stress, strain and heat generation and improving tire bead durability. The tire comprises a tread rubber, a belt layer, a carcass cord layer and a pair of wire rings. At the bead area, between the outer side of the carcass cord layer and the sidewall rubber, two layers of stress buffer rubber with different stiffness and thickness are arranged, and a carcass cord is sandwiched between the two layers of stress buffer rubber; the two layers of stress buffer rubber with different stiffness and thickness connected are: the Shore hardness of the first layer of low hardness rubber from the carcass cord layer to the outside of the sidewall rubber is 63 to 68 degrees, and the thickness is 2 to 5 mm, and the Shore hardness of the second layer of stress buffer rubber is 60 to 65 degrees, and the thickness is 4 to 7 mm; the Shore hardness of the second layer of stress buffer rubber of the two layers of stress buffer rubber with different stiffness is 2 to 5 degrees less than that of the first layer of stress buffer rubber. The radial aircraft tire of the invention has a bead durability improved by more than 80% through the above structural design, and its dynamic performance can meet the requirements of the airworthiness standard (GJB683A). However, the specific range value of its thickness is an empirical value, which cannot be calculated according to the tire plies of different sizes, and its applicability is insufficient.

[0007] Invention CN103009932B discloses a radial aircraft tire that can reduce interface stress and improve tire bead durability. In the tire bead area, a transition rubber layer is arranged on the outside of the carcass cord layer, with a thickness of 2 to 4 mm and a Shore hardness of 60 to 70 degrees; two layers of buffer fiber cord layers are arranged outside the transition rubber, with a cord density of 35 to 90 cords / 100 mm, an angle between the cord and the circumferential direction of 20° to 90°, and the warps of the two layers of cords are arranged crosswise relative to the radial direction. The improved radial aircraft tire can reduce the interface stress, strain and heat generation between the carcass and the outer rubber in the tire bead area, and the tire bead durability under harsh conditions is improved by more than 80%, and its dynamic performance can meet the requirements of the airworthiness standard (GJB683A). However, the hardness of the two layers of buffer rubber set in the invention gradually decreases from the inside to the outside, which is not conducive to the wear resistance of the tire bead, and the hardness and modulus of the sidewall rubber are not clear, and its modulus gradient is unclear.

[0008] Improving the tire bead durability will provide a strong guarantee for the safety performance of the aircraft and will greatly reduce the maintenance and use costs of the aircraft. Therefore, how to reduce the shear stress between the tire bead rubber and the tire bead positive cord layer and the strain of the tire bead rubber through reasonable structural design and rubber modulus ratio is a key link in improving the tire bead durability of radial aircraft tires and is an urgent problem to be solved by those skilled in the art. Summary of the invention

[0009] In view of the defects existing in the above-mentioned prior art, the present invention provides a high-durability gradient reinforced composite material for aircraft tires and an aircraft tire bead structure and a molding method and application thereof. Through the design of the hardness gradient and modulus gradient of the high-durability gradient reinforced composite material, the hardness and modulus of the bead rubber material gradually increase from the inside to the outside in the thickness direction. The outer layer has high hardness and high modulus to enhance the wear resistance, and the inner layer has low hardness and low modulus to reduce the shear stress between the carcass cord layer, thereby comprehensively improving the durability of the aircraft tire bead.

[0010] In a first aspect, the present invention provides a high-durability gradient reinforced composite material for aircraft tires, wherein the Shore A hardness of the high-durability gradient reinforced composite material is 50°-75°, the 100%-300% tensile stress is ≥5MPa, the tensile strength is ≥20MPa, and the elongation at break is ≥450%;

[0011] In the thickness direction, the high-durability gradient reinforced composite material has a hardness gradient and / or a modulus gradient.

[0012] Preferably, the hardness and modulus of the high-durability gradient reinforced composite material gradually increase from the inside to the outside in the thickness direction.

[0013] The impact load on aircraft tires is much greater than that on automobile tires, and the sinking rate is 20%-80%, while the sinking rate of automobile tires is about 10%-20%. Therefore, the mechanical performance indicators of rubber materials used in aircraft tires are generally higher than those of automobile tires, and the main mechanical performance indicators include hardness, tensile stress, tensile strength, and elongation at break. The Shore A hardness of the composite material of the present invention is 50°-75°, the tensile stress of 100%-300% is ≥5MPa, the tensile strength is ≥20MPa, and the elongation at break is ≥450%. The hardness gradient and modulus gradient suitable for aircraft tires are further introduced in the thickness direction. When the composite material is used in the tire bead structure of the aircraft tire, the tire bead structure can have performance characteristics such as flexibility and wear resistance, and at the same time optimize the stress distribution and material durability, so as to meet the high performance requirements of the aircraft tire in the complex use environment.

[0014] Preferably, the hardness gradient and / or modulus gradient of the high-durability gradient reinforced composite material is formed by at least one of the following methods:

[0015] 1) The high-durability gradient reinforced composite material includes a reinforcing agent, and the content of the reinforcing agent is distributed in a gradient manner in the thickness direction;

[0016] 2) In the thickness direction, the high-durability gradient-reinforced composite material forms a vulcanization degree gradient.

[0017] The reinforcing agent for aircraft tires includes at least one of carbon black, white carbon black, graphene, and carbon nanotubes. While reducing the cost of rubber, the reinforcing agent can significantly improve the physical and mechanical properties of tire rubber, such as strength, wear resistance, wet skid resistance, and tear resistance, and reduce rolling resistance and economic costs. The content of the reinforcing agent will have a significant effect on the hardness and modulus of the rubber. Therefore, by distributing reinforcing agents with different content gradients in the rubber matrix, the desired performance gradient can be quickly and easily obtained. On the other hand, the performance of rubber is closely related to the vulcanization process. Under the same material composition, changing the vulcanization temperature and / or vulcanization time can adjust the vulcanization degree of the rubber. The desired performance gradient can also be achieved through the gradient difference of the vulcanization degree.

[0018] Therefore, the present invention can effectively form a performance gradient in the composite material by designing the gradient distribution of the reinforcing agent content and / or regulating the gradient of the vulcanization degree, thereby meeting further design requirements. The specific reinforcing agent content and vulcanization process conditions can be designed and regulated based on the rubber compound ratio and performance requirements.

[0019] Preferably, the high-durability gradient reinforced composite material comprises n reinforcement layers stacked in sequence, where n is an integer greater than 1, and the composite material satisfies at least one of the following conditions:

[0020] 1) The reinforcing agent content of the first reinforcing layer located at the innermost side is C1, and the reinforcing agent content of the nth reinforcing layer is C n , C n Independent satisfaction: C1×p n-1 , content coefficient p is 1.1-2;

[0021] 2) The Shore A hardness of the first reinforcement layer located on the innermost side is A1, and the Shore A hardness of the nth reinforcement layer is A n , A n Independent satisfaction: A1×j n-1 , hardness coefficient j is 1.01-1.5;

[0022] 3) The 100%-300% tensile stress of the first reinforcement layer located at the innermost side is E1, and the 100%-300% tensile stress of the nth reinforcement layer is E n , E n Independently satisfy E1×k n-1 , the modulus coefficient k is 1.05-2.

[0023] The composite material itself can be an integrated structure, and the performance gradient within the integrated structure can be obtained by the aforementioned adjustment method, but it is more preferable to use layered materials with performance gradients to form an integrated structure through a vulcanization process. The layered stacking method is conducive to accurately controlling the performance increment or decrement value of each layer, and is less affected by the mixing process. On the other hand, the specific rubber ratio of each layer can be adjusted as needed, such as using the same base rubber with different types of reinforcing agents or other additives, or adjusting the types and amounts of various components such as the base rubber, so as to achieve the desired comprehensive performance. In addition, layered stacking is also more convenient for dividing the vulcanization process adjustment area, and it is more accurate when obtaining the performance gradient based on the formation of the vulcanization degree gradient.

[0024] The present invention sets the value of the hardness coefficient j between 1.01 and 1.5 to ensure that the hardness of each outer layer of the composite material is higher than that of the inner layer from the inside to the outside, which helps to optimize the stress distribution. The higher the hardness, the stronger the rigidity of the rubber, which helps to enhance the support force of the outer layer of the tire bead, reduce the excessive deformation of the wheel rim due to repeated stress, and avoid early wear and aging of the contact surface between the wheel rim and the tire bead rubber layer. Similarly, the modulus determines the tensile strength of the material. The higher the modulus, the more rigid the material, and the more it can withstand large deformation without permanent deformation. The modulus coefficient k is set to 1.05-2. From the inside to the outside, the modulus of each outer layer of reinforcing rubber is higher than that of the inner layer. This increase in modulus enables the tire bead to have an appropriate balance of rigidity and flexibility at different locations. The high modulus of the outer layer can withstand greater stress, while the rubber with a lower modulus of the inner layer helps to alleviate the transmission of external stress and avoid local damage caused by excessive rigidity. Moreover, the present invention preferably designs the content coefficient p, and the reinforcing agent content of each outer layer of the composite material is higher than that of the inner layer from the inside to the outside, so that the above-mentioned performance gradient is simply and effectively formed during the overall vulcanization process, that is, the above-mentioned reinforcing agent content gradient has a good correspondence and designability with the corresponding hardness gradient and modulus gradient.

[0025] In a second aspect, the present invention provides a high-durability aircraft tire bead structure, including a wire ring, an apex rubber, a sidewall rubber, a bead reinforcing rubber and a bead rubber;

[0026] A bead reinforcing rubber is provided between the bead rubber and the rim edge. The bead reinforcing rubber adopts the aforementioned high-durability gradient reinforced composite material. The hardness and / or modulus of the bead reinforcing rubber gradually increases from the bead rubber toward the rim edge.

[0027] Preferably, the tire bead reinforcing rubber mainly comprises base rubber, reinforcing agent (or reinforcing agent), and one or more of silane coupling agent, protective wax, antioxidant, leveling agent, accelerator, vulcanizing agent, and anti-scorch agent.

[0028] In parts by weight, the tire bead reinforcement rubber raw materials include:

[0029] 100 parts of base rubber

[0030] Enhancer 20-100 parts

[0031] Additives 5-50 parts

[0032] In the base rubber, the amount of natural rubber accounts for 70-100wt%, and synthetic rubber components such as cis-1,4-dimethyl-1-butyl rubber and styrene-butadiene rubber can also be selected. For example, the total amount of base rubber is 100 parts, of which 90 parts are natural rubber and 10 parts are styrene-butadiene rubber. In order to meet the high performance index requirements of rubber materials for aircraft tires, the base rubber is mainly high-performance natural rubber. The proportion of natural rubber in every hundred parts of base rubber is 70-100wt%, preferably 80-100wt%. The proportion of natural rubber in aircraft tire rubber is much higher than that in automobile tire rubber. In addition, a small amount of reclaimed rubber can be selected in the base rubber, and the content of reclaimed rubber is below 5wt%, preferably below 3wt%.

[0033] The reinforcing agent includes at least one of carbon black (such as N330 carbon black, N339 carbon black, N220 carbon black), white carbon black, graphene, and carbon nanotubes. The reinforcing agent (or reinforcing agent) is beneficial to improving the hardness, wear resistance and tensile strength of the rubber compound. In the present invention, based on the use of the reinforcing agent, in order to form a performance gradient, the content of the reinforcing agent is preferably designed in a gradient.

[0034] The auxiliary agents include but are not limited to silane coupling agents, protective waxes, antioxidants, leveling agents, accelerators, vulcanizing agents, anti-scorch agents, etc.

[0035] The silane coupling agent comprises at least one of Si-69, KH-550, KH-560, KH-570, KH-845-4, TESPT and TESPD, and its amount is about 0.1-10% of the amount of the reinforcing agent;

[0036] The protective wax includes at least one of paraffin oil, protective wax RP-3, and protective wax RW-101, and the amount is about 1-10 parts;

[0037] The antioxidants mainly include amine antioxidants and phenol antioxidants, wherein the amine antioxidants include ketoamines, aldehyde amines, diaryl secondary amines, diphenylamines, p-phenylenediamines, and alkylaryl secondary amines, and the phenol antioxidants include substituted monophenols, polyphenols, sulfurized disubstituted phenols, and alkylene disubstituted phenols. Specifically, the antioxidant for aircraft tires may include at least one of antioxidant 4020, antioxidant 4010NA, antioxidant RD, and antioxidant IPPD, and the total amount is about 0.2-2% of the weight of the base rubber;

[0038] The homogenizer includes at least one of homogenizer A78, homogenizer 145A, and homogenizer UB4000, and the amount is 1-5 parts;

[0039] The types of accelerators mainly include thioamino, guanidine, thiazole, sulfenamide and thiuram, and specifically include at least one of accelerator DZ, accelerator NOBS and accelerator TMTD, and the amount is 1-5 parts;

[0040] The vulcanizing agent includes at least one of sulfur, DCP and zinc oxide, and the amount is 1-10 parts;

[0041] The anti-scorching agent mainly includes nitroso compounds, sulfonamides, N-cyclohexylthiophthalimide, N,N'-m-phenylene bismaleimide, etc., and specifically includes at least one of CTP, HTM, NA and salicylic acid, and the dosage is 0.1-3 parts.

[0042] In the existing field of aviation radial tire technology, the hardness and modulus of the bead reinforcement rubber are basically the same, the use function is single, and there is a lack of non-uniform design for performance. Due to the different loads and stress states borne by different parts of the bead, the uniform hardness structure will lead to aggravated stress concentration, especially between the rubber and the carcass cord layer and the area close to the rim. At the same time, because the bead undergoes repeated deformation during high-speed rolling, the uniform modulus structure cannot adapt to the stress difference inside the bead, resulting in the inability to effectively disperse the strain. Dynamic strain is concentrated in local areas, resulting in energy loss and conversion into heat, which in turn aggravates the heat generation problem of rubber materials. In addition, the viscoelasticity of rubber materials causes strain to lag behind stress. The uniform modulus design cannot form a smooth strain transition in different stress areas, which will produce greater internal friction and hysteresis loss. Heat accumulation accelerates rubber aging and performance degradation.

[0043] The present invention optimizes the stress distribution of the tire by providing a bead reinforcing rubber with a hardness gradient and a modulus gradient between the bead rubber and the rim edge. Specifically, the hardness gradient and modulus gradient design enable the high hardness and high modulus of the outer reinforcing rubber to adapt to the high pressure stress near the rim edge, while the hardness and modulus of the inner reinforcing rubber are lower, so that it can buffer the stress when it is close to the carcass cord layer. Through the gradient design of hardness and modulus, the bead reinforcing rubber shows significant advantages in stress distribution, reducing heat generation, and improving fatigue resistance, making the tire more durable and reliable under high frequency and high load conditions, meeting the stringent use requirements of aviation tires.

[0044] Preferably, from the bead rubber toward the rim edge, the high-durability gradient reinforced composite material includes a first reinforcement layer, a second reinforcement layer and a third reinforcement layer in sequence, satisfying at least one of the following conditions:

[0045] 1) The Shore A hardness A1 of the first reinforcement layer is 55°-60°, and the 100%-300% tensile stress is 5-10MPa;

[0046] 2) The Shore A hardness A2 of the second reinforcement layer is 60°-65°, and the 100%-300% tensile stress is 8-14MPa;

[0047] 3) The Shore A hardness A3 of the third reinforcement layer is 65°-70°, and the 100%-300% tensile stress is ≥12MPa.

[0048] In view of the fact that the layered stacking method can more accurately design and regulate the hardness gradient and modulus gradient as well as the size limitation of the bead reinforcement rubber, when applied to high-durability aviation tires, the composite material of the present invention is preferably designed with three reinforcement layers from the bead rubber toward the rim edge, and the hardness and modulus of the three reinforcement layers gradually increase.

[0049] Specifically, each reinforcement layer meets the requirements of Shore A hardness of 50°-75°, 100%-300% tensile stress ≥5MPa, tensile strength ≥20MPa, and elongation at break ≥450%. In addition to forming a gradient distribution of hardness and modulus for each reinforcement layer, the tensile strength and elongation at break also show an increasing trend from the first reinforcement layer to the third reinforcement layer.

[0050] Preferably, the tire bead structure satisfies at least one of the following conditions:

[0051] 1) The ratio of the width W1 of the first reinforcement layer to the rim edge radius R is 1-1.2;

[0052] 2) The ratio of the width W2 of the second reinforcement layer to the width W1 of the first reinforcement layer is 1.5-2;

[0053] 3) The ratio of the width W3 of the third reinforcement layer to the width W2 of the second reinforcement layer is 1.5-2;

[0054] 4) The ratio of the total thickness of the tire bead reinforcement rubber and the sidewall rubber B1 to the total thickness of the apex rubber top skeleton material B2 satisfies:

[0055] When measuring the total thickness B1 of the tire bead reinforcement rubber and the sidewall rubber, the thickness refers to the size of the film from the tire bead rubber to the rim edge on the cross section through the tire axis, and the "tire axis" refers to the tire rotation axis. When the reinforcement layer is a uniform film, the thickness is a single thickness value. When the reinforcement layer has an arc or other irregular structure, the thickness is measured according to the maximum value. For example, when the first reinforcement layer is an arc-shaped long strip of film, its thickness is the distance from the highest point of the arc side to the other side. The width is the maximum size of the film in the direction perpendicular to the thickness direction on the cross section. According to the stress conditions of the tire bead, the bonding and reinforcement effects of the tire bead reinforcement rubber, preferably, the thickness of the first reinforcement layer ≥ the thickness of the second reinforcement layer ≥ the thickness of the third reinforcement layer, and the width of the first reinforcement layer ≤ the width of the second reinforcement layer ≤ the width of the third reinforcement layer.

[0056] The total thickness B2 of the skeleton material on the top of the apex rubber includes the total thickness of the carcass positive cord, reverse cord and bead reinforcement layer. The setting of the thickness ratio ensures that the bead rubber has sufficient thickness at the contact point with the rim edge, so that the bead can effectively disperse the high pressure stress from the rim edge when in contact with the rim. If the bead thickness is insufficient, the bead rubber has weak support at the rim edge and is prone to excessive deformation or wear due to uneven load. Controlling the ratio within the range of 0.75-1 ensures that the bead area has the necessary thickness to support the pressure of the rim, while not causing the tire to be overly stiff or increase in mass due to excessive thickness.

[0057] The present invention conducts adaptability research on different bead sizes, including designing the width and thickness of the bead reinforcing rubber according to the specific sizes of materials such as the rim, the sidewall rubber, and the apex rubber. Compared with the prior art that prepares a reinforcing rubber of uniform size and a single combination with the tire, the present invention has better pertinence and actual reinforcement effect, especially in the harsh use environment where the impact load on aviation tires is much greater than that on automobile tires. In addition to designing the hardness and modulus of the bead reinforcing rubber, configuring a specific bead reinforcing rubber according to the specific size of the aviation tire has significant significance in terms of performance improvement, durability, and safety assurance.

[0058] Preferably, the tire bead structure satisfies at least one of the following conditions:

[0059] 1) The Shore A hardness of the sidewall rubber is 68°-74°, and the 100%-300% tensile stress is ≥15MPa;

[0060] 2) The Shore A hardness of the apex is 88°-94°;

[0061] 3) The ratio of apex height H to wire ring diameter D satisfies:

[0062] 4) The ratio of the height difference H2 between the top of the apex and the rim to the rim height H1 is 1:(4-9).

[0063] The sidewall rubber is made of wear-resistant rubber, and the base rubber of the wear-resistant rubber includes one or more of natural rubber, butyl rubber, fluororubber, hydrogenated nitrile rubber and polyurethane rubber. The hardness and modulus of the wear-resistant rubber can be adjusted by filling a reinforcing agent with a high content.

[0064] The apex rubber is made of high modulus rubber, including one or more of high hardness nitrile rubber, high hardness hydrogenated nitrile rubber, polyurethane rubber and silicone rubber. The apex rubber has a high content of reinforcing agent such as carbon black to achieve high modulus. The rubber is extruded after mixing, installed on the wire ring, and then the two are wrapped as one by a cord or a rubber cord. The height of the apex rubber is close to or slightly larger than the wire ring diameter, so that the apex rubber can form a good support structure around the wire ring, optimize the force distribution of the tire bead under high load, and avoid local deformation of the tire bead rubber due to insufficient height. The moderate height ratio ensures that the apex rubber will not be too rigid due to excessive height, nor will it lack support due to insufficient height, thereby achieving balanced stability of the tire bead structure under load.

[0065] By controlling the height difference ratio between the top of the apex and the rim, the contact between the top of the apex and the rim can be controlled, so that the load of the rim is dispersed layer by layer at different parts of the tire bead, avoiding stress concentration on a single contact surface. A reasonable height difference ratio allows the top of the apex to effectively contact the rim without protruding too much, thereby reducing wear or peeling caused by local stress concentration during tire rolling and improving the wear resistance and stability of the tire.

[0066] More preferably, the bead reinforcing rubber extends from the lower sidewall to the bottom of the wire ring; and the wire density of the skeleton cord of the bead reinforcing rubber is less than the density of the carcass cord.

[0067] The skeleton cord density of the tire bead reinforcing rubber is less than that of the carcass cord, and the design forms a modulus transition zone between the tire bead and the carcass layer. The reduction in cord density enables the tire bead reinforcing rubber to achieve a flexible transition in cord density, thereby reducing the modulus difference between the tire bead and the carcass layer and reducing the shear stress between the rubber layer and the cord layer.

[0068] The density transition design of the tire bead reinforcement rubber works in synergy with the hardness and modulus gradient of the reinforcement rubber, making the tire bead structure more smooth in stress transmission and reducing the shear stress concentration between the tire bead layers. This synergy ensures the dynamic stability of the tire bead under high-frequency and high-load conditions, allowing the tire to maintain a longer service life under complex conditions, while enhancing the anti-fatigue performance of the structure, significantly improving the safety and reliability of aviation tires under extreme conditions.

[0069] In a third aspect, the present invention further provides a method for preparing the high-durability aircraft tire bead structure, comprising the following steps:

[0070] Step 1: Cover the wire ring and apex rubber with the carcass cord layer;

[0071] Step 2: Paste the bead reinforcement layer from the bottom of the wire ring upward outside the carcass cord layer;

[0072] Step 3, pasting the high-durability gradient reinforced composite material on the side of the bead reinforcement layer facing the rim edge to form a bead reinforcement glue;

[0073] Step 4, pasting sidewall rubber on the outer side of the high-durability gradient reinforced composite material;

[0074] Step 5: starting from the bottom of the high-durability gradient reinforced composite material, wrap the bead rubber around the bead reinforcement layer and / or the carcass cord layer.

[0075] Preferably, the carcass ply includes a turn-up ply and a front ply, and the step 1 of wrapping the wire ring and the apex rubber into an integral structure specifically includes:

[0076] 1) Laying the turned-up cord layer by layer on the aircraft tire forming equipment;

[0077] 2) Install the wire ring and apex rubber at the designated position, and turn up the curtain fabric manually or with a turn-up device;

[0078] 3) Wrap the positive cord fabric around the reverse cord fabric.

[0079] Preferably, from the bead rubber to the rim edge direction, the high-durability gradient reinforced composite material includes a first reinforcement layer, a second reinforcement layer and a third reinforcement layer in sequence. In step three, the high-durability gradient reinforced composite material specifically includes:

[0080] 1) Outside the bead reinforcement layer, a first reinforcement layer is attached upward from the corresponding position on the top of the wire ring; the first reinforcement layer is preferably an arc-shaped strip of film, the thickness of which gradually decreases from the middle of the film to the two ends, and the arc-shaped strip of film can be symmetrical or asymmetrical in configuration, so as to better fill the concave area outside the bead reinforcement layer;

[0081] 2) Outside the first reinforcement layer, start to stick the second reinforcement layer upward from the corresponding position in the middle of the wire ring; on the basis of the first reinforcement layer, the second reinforcement layer can be made of a film with uniform thickness;

[0082] 3) Outside the second reinforcement layer, at or near the starting position of the second reinforcement layer, a third reinforcement layer is pasted upward; the third reinforcement layer can be made of a film with uniform thickness.

[0083] Preferably, in step 4, the sidewall rubber is adhered to the third reinforcement layer from top to bottom, preferably from the tire shoulder portion downward.

[0084] Preferably, in step five, the bead rubber starts from the bottom of the third reinforcement layer and at least covers the entire bottom of the bead structure.

[0085] In a fourth aspect, the present invention also provides an application of the high-durability gradient reinforced composite material, or the high-durability aviation tire bead structure, or the high-durability aviation tire bead structure obtained by the preparation method in military and / or civil aviation tires.

[0086] The present invention has at least the following beneficial effects:

[0087] (1) The high-durability gradient-reinforced composite material for aircraft tires provided by the present invention and the high-durability aircraft tire bead structure using the composite material, by designing a hardness gradient and / or modulus gradient in the thickness direction of the composite material, make the outer layer of the composite material have higher hardness and modulus, can effectively withstand high pressure stress, and reduce material wear and aging. At the same time, the hardness and modulus of the inner layer are relatively low, which can alleviate stress differences, reduce shear stress, and optimize stress distribution. This gradient design effectively reduces the concentration of dynamic strain, reduces heat generation, avoids material aging and performance degradation caused by high temperature, and significantly improves the durability and fatigue resistance of the composite material and its bead structure, meeting the use requirements of aircraft tires under high load and high frequency strain conditions.

[0088] (2) The present invention controls the hardness, height and other dimensions of the apex rubber so that the apex rubber has an appropriate support height in the tire bead, which not only provides effective structural support but also avoids rigidity imbalance caused by excessive or insufficient height. At the same time, these ratios ensure reasonable contact between the top of the apex rubber and the rim, so that the load is dispersed layer by layer, effectively avoiding stress concentration, reducing local wear or peeling, and improving the wear resistance and stability of the tire bead as a whole.

[0089] (3) The present invention comprehensively designs the multi-layered gradient reinforced composite material and the size and performance of each reinforcement layer thereof based on the size and performance of the components of the aircraft tire, such as the rim, wire ring, apex rubber and sidewall rubber, and simply and effectively molds the high-durability gradient reinforced composite material and obtains a high-durability aircraft tire bead structure by adjusting the amount of reinforcing agent and / or the degree of vulcanization. The aforementioned design and molding method have wide adaptability and adjustability and can be promoted for use in multiple models of military or civil aircraft tires. BRIEF DESCRIPTION OF THE DRAWINGS

[0090] Figure 1 It is a cross-sectional view of the bead structure of the high-durability aviation tire of the present invention;

[0091] Figure 2 It is a schematic diagram of the dimensions of the bead structure of the high-durability aviation tire of the present invention.

[0092] Explanation of the reference numerals: 1-wire ring, 2-apex rubber, 3-carcass cord layer, 4-bead reinforcement layer, 5-first reinforcement layer, 6-second reinforcement layer, 7-third reinforcement layer, 8-sidewall rubber, 9-bead rubber, 10-rim. DETAILED DESCRIPTION

[0093] In order to better understand the above technical solution, the above technical solution will be described in detail below in combination with the specification and specific implementation methods. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0094] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. The singular forms "a", "said" and "the" used in the embodiments of the present invention and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings, and "multiple" generally includes at least two.

[0095] It should also be noted that the term "includes", "comprising" or any other variation thereof is intended to cover non-exclusive inclusion, so that a commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprising a ..." do not exclude the existence of other identical elements in the commodity or device including the elements.

[0096] The following will be combined with the attached Figure 1-2 The invention discloses a high-durability aircraft tire bead structure in detail. The thickness of the high-durability gradient reinforced composite material (or bead reinforcing rubber) of the invention refers to the size of the film from the bead rubber to the rim edge on the section passing through the tire axis, and the "tire axis" refers to the tire rotation axis. The width of the high-durability gradient reinforced composite material (or bead reinforcing rubber) refers to the maximum size of the film in the direction perpendicular to the thickness direction on the section passing through the tire axis.

[0097] like Figure 1 As shown, a high-durability aviation tire bead structure made of high-durability gradient reinforced composite material specifically includes: a steel bead 1, an apex rubber 2, a carcass cord layer 3, a bead reinforcement layer 4, a sidewall rubber 8, a bead reinforcing rubber, a bead rubber 9 and a rim 10 and other tire components, wherein:

[0098] (1) The bead reinforcing rubber is formed of a high-durability gradient reinforced composite material and is arranged between the bead rubber 9 and the edge of the rim 10. From the bead rubber 9 to the edge of the rim 10, the bead reinforcing rubber forms a gradually increasing hardness gradient and / or a gradually increasing modulus gradient. Preferably, both the hardness and the modulus gradually increase.

[0099] The high-durability gradient reinforced composite material comprises n reinforced layers stacked in sequence, where n is an integer greater than 1, preferably n is 3 to 5. Preferably, but not limited to, the hardness gradient and / or modulus gradient can be formed by at least one of the following methods:

[0100] 1) Enhancer content gradient:

[0101] The reinforcing agent content of the first reinforcing layer 5 located at the innermost side is C1, and the reinforcing agent content of the nth reinforcing layer is C n , C n Independent satisfaction: C1×p n-1 , content coefficient p is 1.1-2;

[0102] Optionally, when the composite material comprises three reinforcement layers, the ratio of the reinforcement content of the first reinforcement layer 5: the reinforcement content of the second reinforcement layer 6: the reinforcement content of the third reinforcement layer 7 is (4-5): (5-6): (6-7);

[0103] The reinforcing agent includes at least one of carbon black, white carbon black, graphene and carbon nanotubes.

[0104] 2) Vulcanization time gradient:

[0105] The curing time of the first reinforcement layer 5 located at the innermost side is t1, and the curing time of the nth reinforcement layer is t n , t n Independent satisfaction: t1×q n-1 , the time coefficient q is 1.05-2;

[0106] Optionally, when the composite material comprises three reinforcement layers, the ratio of the vulcanization time of the first reinforcement layer 5: the vulcanization time of the second reinforcement layer 6: the vulcanization time of the third reinforcement layer 7 is 1: (1.05-1.5): (1.3-1.8);

[0107] 3) Curing temperature gradient: The curing temperature of the first reinforcing layer 5 located on the innermost side is T1, and the curing temperature of the nth reinforcing layer is T n , T n Independent satisfaction: T1×m n-1 , the temperature coefficient m is 1.05-1.5;

[0108] Optionally, when the composite material includes three reinforcement layers, the ratio of the vulcanization temperature of the first reinforcement layer 5: the vulcanization temperature of the second reinforcement layer 6: the vulcanization temperature of the third reinforcement layer 7 is 1: (1.05-1.25): (1.2-1.5).

[0109] Performance gradient design and regulation can be achieved through one or a combination of conditions among the gradient of reinforcing agent content, the gradient of vulcanization temperature, and the gradient of vulcanization time. However, it is preferred to regulate one or two conditions, otherwise the process cost will be high and the gradient accuracy will be difficult to control.

[0110] The tire bead reinforcing rubber comprises at least a first reinforcing layer 5, a second reinforcing layer 6 and a third reinforcing layer 7, and the performance gradient is designed as follows:

[0111] 1) Hardness gradient:

[0112] The Shore A hardness of the first reinforcement layer 5 located at the innermost side is A1, and the Shore A hardness of the nth reinforcement layer is A n , A n Independent satisfaction: A1×j n-1 , hardness coefficient j is 1.01-1.5;

[0113] Optionally, when the composite material includes three reinforcement layers, the Shore A hardness A1 of the first bead reinforcement layer is 55°-60°, the Shore A hardness A2 of the second bead reinforcement layer is 60°-65°, the Shore A hardness A3 of the third bead reinforcement layer is 65°-70°, and A1<A2<A3;

[0114] 2) Modulus gradient:

[0115] The 100%-300% elongation stress of the first reinforcement layer 5 located at the innermost side is E1, and the 100%-300% elongation stress of the nth reinforcement layer is E n , E n Independently satisfy E1×k n-1 , the modulus coefficient k is 1.05-2.

[0116] Optionally, the 300% elongation stress E1 of the first reinforcement layer 5 is 5-10 MPa, the 300% elongation stress E2 of the second reinforcement layer 6 is 8-14 MPa, the 300% elongation stress E3 of the third bead reinforcement layer is ≥12 MPa, and E1<E2<E3;

[0117] 3) Width gradient, see attached Figure 2 :

[0118] 3.1) The ratio of the width W1 of the first reinforcement layer 5 to the edge radius R of the rim 10 is 1-1.2;

[0119] 3.2) The ratio of the width W2 of the second reinforcement layer 6 to the width W1 of the first reinforcement layer 5 is 1.5-2;

[0120] 3.3) The ratio of the width W3 of the third reinforcement layer 7 to the width W2 of the second reinforcement layer 6 is 1.5-2.

[0121] 4) Optional thickness gradient:

[0122] The thickness of the first reinforcement layer 5 located at the innermost side is b1, and the thickness of the nth reinforcement layer is b n , b n Independent satisfaction: b1×s n-1 , thickness coefficient s is 0.2-0.7;

[0123] Optionally, when the composite material includes three reinforcement layers, the ratio of the thickness of the first reinforcement layer 5: the thickness of the second reinforcement layer 6: the thickness of the third reinforcement layer 7 is (5-6): (2-3): (1-1.5).

[0124] (2) Sidewall rubber 8, comprising wear-resistant rubber, Shore A hardness of 68°-74°, 300% modulus of elongation ≥15 MPa, thickness: 1.5-2.5 mm; the wear-resistant rubber comprises one or more of natural rubber, butyl rubber, fluororubber, hydrogenated nitrile rubber and polyurethane rubber, and is preferably combined with a reinforcing agent to obtain the desired performance parameters.

[0125] (3) Apex 2 and wire ring 1, refer to the attached Figure 2 :

[0126] The apex 2 is located on the top of the wire ring 1, and the wire ring 1 and the apex 2 are covered by the carcass ply 3 to form an integral structure, wherein:

[0127] Apex 2 is made of high modulus rubber with a Shore A hardness of 88°-94°;

[0128] The ratio of the height H of the apex 2 to the diameter D of the wire ring 1 satisfies:

[0129] The ratio of the height difference H2 between the top of the apex 2 and the wheel rim to the wheel rim height H1 is 1:(4-9);

[0130] The high modulus rubber material includes one or more of high hardness nitrile rubber, high hardness hydrogenated nitrile rubber, polyurethane rubber and silicone rubber, and is preferably combined with a reinforcing agent to obtain the required hardness and other parameters.

[0131] In addition, the ratio of the total thickness B1 of the tire bead reinforcement rubber and the sidewall rubber 8 to the total thickness B2 of the top skeleton material of the apex rubber 2 satisfies:

[0132] The top skeleton material of the apex rubber 2 is the skeleton laminated layer at the top position of the apex rubber 2, including the carcass positive cord fabric, the reverse cord fabric and the bead reinforcement layer 4.

[0133] (4) The bead reinforcement layer 4 is attached upward from the bottom of the wire ring 1 outside the carcass ply 3, and the wire density of the skeleton cord of the bead reinforcement layer 4 is less than the density of the carcass ply 3.

[0134] (5) Bead rubber 9, starting from the bottom of the high-durability gradient reinforced composite material, wraps around the bead reinforcement layer 4 and / or the carcass cord layer 3. Preferably, the bead rubber 9 starts from the bottom of the third reinforcement layer 7 and at least covers the entire bottom of the bead structure.

[0135] The molding method of the high-durability aircraft tire bead structure comprises the following steps:

[0136] Step 1: Covering the wire ring 1 and the apex rubber 2 with the carcass cord layer 3, including:

[0137] 1.1) Lay the turned-up cord layer by layer on the aircraft tire forming equipment;

[0138] 1.2) Install the wire ring 1 and apex 2 at the designated position, and turn up the cord fabric manually or with a turn-up device;

[0139] 1.3) Wrap the positive cord fabric on the reverse cord fabric;

[0140] Step 2: attaching a bead reinforcement layer 4 from the bottom of the wire ring 1 upward outside the carcass ply 3, wherein the wire density of the skeleton cord of the bead reinforcement layer 4 is less than the density of the carcass ply 3;

[0141] Step 3: Paste the high-durability gradient reinforced composite material on the side of the bead reinforcement layer 4 facing the edge of the rim 10, wherein from the bead rubber 9 to the edge of the rim 10, the high-durability gradient reinforced composite material includes a first reinforcement layer 5, a second reinforcement layer 6 and a third reinforcement layer 7 in sequence, including:

[0142] 1) Outside the bead reinforcement layer 4, a first reinforcement layer 5 is attached upward from the corresponding position on the top of the wire ring 1; the first reinforcement layer 5 is preferably an arc-shaped strip of film, the thickness of which gradually decreases from the middle of the film to the two ends, and the arc-shaped strip of film can be symmetrical or asymmetrical in configuration, so as to better fill the concave area outside the bead reinforcement layer 4;

[0143] 2) Outside the first reinforcement layer 5, a second reinforcement layer 6 is pasted upward from the corresponding position in the middle of the wire ring 1; on the basis of the laying of the first reinforcement layer 5, the second reinforcement layer 6 can be made of a film with uniform thickness;

[0144] 3) Outside the second reinforcement layer 6, at or near the starting position of the second reinforcement layer 6, a third reinforcement layer 7 is pasted upward; the third reinforcement layer 7 may be made of a film with uniform thickness;

[0145] Step 4: Paste the sidewall rubber 8 on the outer side of the high-durability gradient reinforced composite material, and paste the sidewall rubber 8 from top to bottom relative to the third reinforcement layer 7, preferably from the shoulder part to the bottom;

[0146] Step 5: Starting from the bottom of the high-durability gradient reinforced composite material, the bead rubber 9 is wrapped around the bead reinforcement layer 4 and / or the carcass cord layer 3. Preferably, the bead rubber 9 starts from the bottom of the third reinforcement layer 7 and at least covers the entire bottom of the bead structure.

[0147] Example 1

[0148] The high-durability aircraft tire bead structure of this embodiment includes: a wire ring, an apex rubber, a carcass cord layer, a bead reinforcement layer, a sidewall rubber, a bead reinforcing rubber, a bead rubber and a rim, wherein:

[0149] (1) Bead reinforcing rubber, composed of a high-durability gradient reinforced composite material, is arranged between the bead rubber and the rim edge. The high-durability gradient reinforced composite material includes three reinforcing layers stacked in sequence. The rubber composition of the first reinforcing layer, the second reinforcing layer and the third reinforcing layer is basically the same. The carbon black reinforcing agent content gradually increases from the bead rubber to the rim edge. The carbon black content ratio of the first reinforcing layer, the second reinforcing layer and the third reinforcing layer is 4:5:6, so that the hardness of the first reinforcing layer, the second reinforcing layer to the third reinforcing layer gradually increases, and the modulus gradually increases. Each reinforcing layer satisfies the tensile strength ≥ 20MPa and the elongation at break ≥ 450%, wherein:

[0150] 1.1 The first reinforcement layer is an arc-shaped configuration, with a Shore A hardness A1 of 55°, a 300% modulus of elongation E1 of 8 MPa, a width of 25 mm, and a thickness of 5.5 mm at the top of the arc; the ratio of the thickness of the first reinforcement layer to the rim edge radius R is 1.1;

[0151] 1.2 The second reinforcement layer has a Shore A hardness A2 of 60°, a 300% modulus of tensile stress E2 of 10 MPa, a width of 40 mm, and a thickness of 2.5 mm;

[0152] 1.3 The third reinforcement layer has a Shore A hardness A3 of 66°, a 300% elongation stress E3 of 13 MPa, a width of 60 mm and a thickness of 1.2 mm.

[0153] (2) Sidewall rubber: Shore A hardness of 72°, 300% modulus of elongation ≥ 15 MPa, thickness 1.8 mm; total thickness B1 of bead reinforcement rubber and sidewall rubber is 11 mm;

[0154] (3) Apex and wire ring, the Shore A hardness of the apex is 90°;

[0155] The ratio of the apex height H to the wire ring diameter D is

[0156] The ratio of the height difference H2 between the top of the apex and the rim to the rim height H1 is 1:7;

[0157] The total thickness of the tire bead reinforcement rubber and the sidewall rubber B1 is the ratio of the total thickness of the top frame material of the apex rubber B2 is 0.85.

[0158] (4) Bead reinforcement layer, extending from the lower sidewall to the bottom of the wire ring, the wire density of the skeleton cord of the bead reinforcement layer is less than the density of the carcass cord;

[0159] (5) Bead rubber, starting from the bottom of the third reinforcement layer, wraps around the carcass cord layer and bead reinforcement layer on the outside of the bottom of the wire ring, covering the bottom of the entire bead structure.

[0160] The method for forming a bead structure of a high-durability aircraft tire comprises the following steps:

[0161] The molding method of the high-durability aircraft tire bead structure comprises the following steps:

[0162] Step 1: Wrap the wire ring and apex rubber into an integral structure through the carcass cord layer, including:

[0163] 1.1) Lay the turned-up cord layer by layer on the aircraft tire forming equipment;

[0164] 1.2) Install the wire ring and apex rubber at the designated position, and reverse the curtain fabric through the reverse device;

[0165] 1.3) Covering the reversed cord fabric with the forward cord fabric to form the overall structure;

[0166] Step 2: attaching a bead reinforcement layer from the bottom of the wire ring upward outside the carcass ply, wherein the wire density of the skeleton cord of the bead reinforcement layer is less than the density of the carcass ply;

[0167] Step 3: sequentially attaching the first reinforcement layer, the second reinforcement layer and the third reinforcement layer to the side of the bead reinforcement layer facing the rim edge, including:

[0168] 1) Outside the tire bead reinforcement layer, the first reinforcement layer in an arc strip shape is attached upward from the top of the wire ring;

[0169] 2) Outside the first reinforcement layer, the second reinforcement layer with uniform thickness is pasted upward from the middle of the wire ring;

[0170] 3) outside the second reinforcement layer, at the same height as the starting position of the second reinforcement layer, starting to stick the third reinforcement layer with uniform thickness upwards;

[0171] Step 4: Paste the sidewall rubber from the shoulder portion downward on the outer side of the third reinforcement layer;

[0172] Step 5: Starting from the bottom of the third reinforcement layer, the carcass cord layer and the bead reinforcement layer surrounding the outer side of the bottom of the wire ring are wrapped with bead rubber to cover the bottom of the entire bead structure.

[0173] Example 2-3

[0174] The main difference between Example 2-3 and Example 1 is that the hardness of each reinforcement layer, the 300% modulus of tensile stress and the ratio of the reinforcing agent between each layer are adjusted.

[0175] Embodiment 4-5

[0176] The difference between Example 4-5 and Example 2 is that the width and thickness of each reinforcing layer, the hardness and thickness of the sidewall rubber, and the hardness of the apex rubber are adjusted.

[0177] Comparative Examples 1-3

[0178] The difference between Comparative Examples 1-3 and Example 2 is that the tire bead reinforcing rubber only uses a single reinforcement layer.

[0179] The main parameters of Examples 1-5 and Comparative Examples 1-3 are shown in Table 1:

[0180] Table 1 Main parameters of Examples 1-5 and Comparative Examples 1-3

[0181]

[0182] Test methods and results

[0183] 1. Durability test

[0184] Examples 1-5 and Comparative Examples 1-3 were tested for takeoff under rated conditions in accordance with CTSO-C62e "Aircraft Tires", and the test results were as follows:

[0185] The tire beads of Examples 1-5 all passed 60 takeoff tests and met the airworthiness standards. Among them, the tire beads of Examples 2-5 passed 80 takeoff tests, and the tire beads were intact after the tests without delamination, bulging, etc., and had excellent durability.

[0186] The tire bead of Comparative Example 1 only passed 15 takeoff tests, the tire bead of Comparative Example 2 only passed 45 takeoff tests, and the tire bead of Comparative Example 3 only passed 30 takeoff tests. After the tests, the samples of Comparative Examples 1-3 all had delamination and bulging problems to varying degrees and could not meet the requirements of airworthiness standards.

[0187] 2. Pressure resistance test

[0188] Water was injected into the tire beads of Examples 1-5 and Comparative Examples 1-3, and the pressure at which the tire ruptured as the internal pressure increased, i.e., the so-called rupture pressure, was measured. The pressure at which the conventional aircraft tire ruptured was set to 100, and the values ​​measured in each Example and Comparative Example were expressed as a pressure resistance index. A larger pressure resistance index means better pressure resistance. The test results are shown in Table 2.

[0189] Table 2: Test results of withstand voltage of Examples 1-5 and Comparative Examples 1-3

[0190]

[0191] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they are aware of the basic creative concepts. Therefore, the present invention is intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention. Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention.

Claims

1. A high-durability gradient reinforced composite material for aircraft tires, characterized in that: The high-durability gradient reinforced composite material has a Shore A hardness of 50°-75°, a 100%-300% tensile stress ≥5MPa, a tensile strength ≥20MPa, and an elongation at break ≥450%; In the thickness direction, the high-durability gradient reinforced composite material has a hardness gradient and / or a modulus gradient.

2. The high-durability gradient reinforced composite material according to claim 1, characterized in that: From the inside to the outside in the thickness direction, the hardness and modulus of the high-durability gradient reinforced composite material gradually increase.

3. The high-durability gradient reinforced composite material according to claim 1 or 2, characterized in that: The hardness gradient and / or modulus gradient of the high-durability gradient reinforced composite material is formed by at least one of the following methods: 1) The high-durability gradient reinforced composite material includes a reinforcing agent, and the content of the reinforcing agent is distributed in a gradient manner in the thickness direction; 2) In the thickness direction, the high-durability gradient-reinforced composite material forms a vulcanization degree gradient.

4. The high-durability gradient reinforced composite material according to claim 3, characterized in that: The high-durability gradient reinforced composite material comprises n reinforcement layers stacked in sequence, where n is an integer greater than 1, and the composite material satisfies at least one of the following conditions: 1) The reinforcing agent content of the first reinforcing layer located at the innermost side is C1, and the reinforcing agent content of the nth reinforcing layer is Cn, and Cn independently satisfies: C1×p n-1 , content coefficient p is 1.1-2; 2) The Shore A hardness of the first reinforcement layer located on the innermost side is A1, and the Shore A hardness of the nth reinforcement layer is An. An independently satisfies: A1×j n-1 , hardness coefficient j is 1.01-1.5; 3) The 100%-300% elongation stress of the first reinforcement layer located at the innermost side is E1, and the 100%-300% elongation stress of the nth reinforcement layer is En, and En independently satisfies E1×k n-1 , the modulus coefficient k is 1.05-2.

5. A high-durability aircraft tire bead structure, characterized in that: Including wire ring, apex rubber, sidewall rubber, bead reinforcement rubber and bead rubber; A bead reinforcing rubber is provided between the bead rubber and the rim edge. The bead reinforcing rubber adopts the high-durability gradient reinforced composite material described in any one of claims 1 to 4. The hardness and / or modulus of the bead reinforcing rubber gradually increase from the bead rubber toward the rim edge.

6. The tire bead structure according to claim 5, characterized in that: From the bead rubber toward the rim edge, the high-durability gradient reinforced composite material includes a first reinforcement layer, a second reinforcement layer and a third reinforcement layer in sequence, satisfying at least one of the following conditions: 1) The Shore A hardness A1 of the first reinforcement layer is 55°-60°, and the 100%-300% tensile stress is 5-10MPa; 2) The Shore A hardness A2 of the second reinforcement layer is 60°-65°, and the 100%-300% tensile stress is 8-14MPa; 3) The Shore A hardness A3 of the third reinforcement layer is 65°-70°, and the 100%-300% tensile stress is ≥12MPa.

7. The tire bead structure according to claim 6, characterized in that: The bead structure satisfies at least one of the following conditions: 1) The ratio of the width W1 of the first reinforcement layer to the rim edge radius R is 1-1.2; 2) The ratio of the width W2 of the second reinforcement layer to the width W1 of the first reinforcement layer is 1.5-2; 3) The ratio of the width W3 of the third reinforcement layer to the width W2 of the second reinforcement layer is 1.5-2; 4) The ratio of the total thickness of the tire bead reinforcement rubber and the sidewall rubber B1 to the total thickness of the apex rubber top skeleton material B2 satisfies:

8. The tire bead structure according to any one of claims 5 to 7, characterized in that: The bead structure satisfies at least one of the following conditions: 1) The Shore A hardness of the sidewall rubber is 68°-74°, and the 100%-300% tensile stress is ≥15MPa; 2) The Shore A hardness of the apex is 88°-94°; 3) The ratio of apex height H to wire ring diameter D satisfies: 4) The ratio of the height difference H2 between the top of the apex and the rim to the rim height H1 is 1:(4-9).

9. A method for preparing a high-durability aircraft tire bead structure according to any one of claims 5 to 8, characterized in that: The following steps are involved: Step 1: Cover the wire ring and apex rubber with the carcass cord layer; Step 2: Paste the bead reinforcement layer from the bottom of the wire ring upward outside the carcass cord layer; Step 3, pasting the high-durability gradient reinforced composite material on the side of the tire bead reinforcement layer facing the rim edge; Step 4, pasting sidewall rubber on the outer side of the high-durability gradient reinforced composite material; Step 5: starting from the bottom of the high-durability gradient reinforced composite material, wrap the bead rubber around the bead reinforcement layer and / or the carcass cord layer.

10. Use of the high-durability gradient reinforced composite material as claimed in any one of claims 1 to 4, or the high-durability aircraft tire bead structure as claimed in any one of claims 5 to 8, or the high-durability aircraft tire bead structure obtained by the preparation method of claim 9 in military and / or civil aircraft tires.

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