An aircraft tire cord and method of making the same

Abstract

The application relates to the technical field of aircraft tire cord, and discloses an aircraft tire cord and a preparation method thereof. After two-step plasma treatment (impurity removal + etching), a small particle-shaped protrusion and an etching groove (see figure B / D) are formed on the surface of the PA66 cord, the roughness is increased to Ra >= 1.5 mu m, and mechanical interlocking anchor points are provided; the plasma treatment introduces active oxygen groups (the oxygen content is increased from 14.99% to 40.78%), and forms strong chemical bonds with phenolic resin and butyl pyrrole latex in a RFL dipping solution; the H extraction force is increased by 38% (from 177.2 N to 286 N), which meets the requirements of an aviation tire (>= 280 N), the residual rate of the glue film after dipping is >= 95% (see figure F), which is much higher than that of the untreated cord (a large amount of glue film falls off); the interfacial bonding strength is increased, the delamination failure caused by glue film peeling during tire use is avoided, the breaking strength is only decreased by 3% (from 511 N to 495.6 N), and the integrity of the cord structure is ensured.

Description

Technical Field

[0001] This invention relates to the field of aircraft tire cord technology, specifically to an aircraft tire cord and its preparation method. Background Technology

[0002] As a crucial component of aircraft, aircraft tires bear the entire weight of the aircraft when it is on the ground, ensuring its gliding. During takeoff and landing, the high-speed motion and friction with the ground require tires to provide sufficient power and resistance. Therefore, aircraft tires must meet stringent service conditions, including high load capacity, high speed, high inflation pressure, and large deformation under sag.

[0003] Cord, as the reinforcing material of a tire's skeleton, imparts strength and makes it resistant to bursting. Its performance is crucial for maintaining the tire's size, shape, and service life. Currently, the PA66 impregnated cord used in China still comes from Asahi Kasei of Japan. The pull-out force (H-force) of cord produced domestically in my country does not yet meet the requirements of aircraft tires. Research in this area is still limited. The technology used by Wang Jinglei of Beijing University of Chemical Technology involves adding inorganic powder to the cord impregnation solution to improve the adhesion between the fiber and rubber. However, this method cannot solve the problem of weak adhesion between the cord and the rubber film. Therefore, there is an urgent need for an aircraft tire cord and its preparation method to solve the problems of easy fiber-rubber film detachment and poor fiber-rubber adhesion in existing technologies. Summary of the Invention

[0004] The purpose of this invention is to provide an aircraft tire cord and its preparation method to solve the problems mentioned in the background art.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a method for preparing aircraft tire cord, S1: using plasma with a power of 30W and a speed of 25mm / s to remove surface impurities from PA66 cord; S2: The surface of the PA66 cord treated in step S1 is etched using plasma with a power of 150W and a speed of 25mm / s. S3: Prepare the impregnation solution, wherein the impregnation solution comprises the following components by weight percentage: A phenolic resin solution was obtained by stirring 41.9 parts of deionized water, 0.05 parts of sodium hydroxide, 1.96 parts of resorcinol, and 1.06 parts of formaldehyde at a constant temperature of 25°C for 6 hours. 44.5 parts of butyl pyridine latex, 4.45 parts of 2-vinylpyridine, 3 parts of RF m-methyl solution, and 0.8 parts of ammonia were reacted at a constant temperature of 25°C for 20 hours to obtain RFL impregnation solution; S4: Immerse the PA66 cord treated in step S2 in the RFL impregnation solution, controlling the tensile tension to be 4-10KN, the pH value to be 9-10, and the immersion time to be 30 seconds. S5: Dry the PA66 cord after impregnation at 180℃ for 10 minutes.

[0006] The first step uses 30W low-power atmospheric pressure air plasma to quickly remove oil stains / release agents and other impurities from the surface of PA66 cord, avoiding high-temperature damage to the material itself. The second step uses 150W high-power treatment to generate active particles through air ionization, forming a micron-level rough structure (granular protrusions + grooves) with Ra≥1.5μm on the fiber surface, increasing the specific surface area by approximately 30-50% and significantly improving the mechanical interlocking effect. The third step involves a phenolic resin solution: a resorcinol-formaldehyde system forms a thermosetting resin network under weakly alkaline conditions (pH≈9-10), providing initial adhesive strength; and an RFL solution: butadiene-pyridine latex (butadiene / acrylonitrile copolymer) and 2-ethylhexylene... Alkenylpyridine copolymerization, RF m-methyl condensate (resorcinol-formaldehyde condensate) as crosslinking agent, ammonia water catalyzes the formation of a three-dimensional network structure, giving it high-temperature aging resistance. The fourth step is to impregnate the treated PA66 cord in RFL impregnation solution. Tension control (4-10KN) ensures that the fiber bundles are tightly arranged. The pH 9-10 environment promotes resin crosslinking. The short 30-second impregnation avoids excessive swelling. The fifth step is to perform rapid drying at 180℃ / 10min to quickly cure the film and avoid thermal degradation of PA66. Through two-step plasma treatment (impurity removal + surface etching) and a specially formulated RFL impregnation solution, the surface activity and mechanical interlocking ability of the fibers are enhanced.

[0007] Preferably, the plasma treatment in steps S1 and S2 is atmospheric pressure air plasma.

[0008] In steps S1 and S2, the plasma treatment is performed using atmospheric pressure air plasma, which simplifies equipment requirements, reduces production costs, eliminates the need for a vacuum environment, and is suitable for continuous industrial production. At the same time, the active oxygen free radicals in the air plasma enhance surface oxidation.

[0009] Preferably, in step S2, surface etching forms tiny granular protrusions and etched grooves on the surface of the PA66 cord, increasing the surface roughness.

[0010] Preferably, the oxygen content of the RFL impregnation solution in step S3 is 40.78%, which is formed by the chemical bonding of the surface-active groups after plasma treatment with the impregnation solution.

[0011] After plasma treatment, the surface-active groups (such as hydroxyl and carboxyl groups) of PA66 form strong chemical bonds with the phenolic resin and butadiene-pyridine latex in the impregnation solution. The increased oxygen content (XPS data) indicates enhanced chemical bonding, and the film residue rate is ≥95% (Figure F), thus avoiding interfacial peeling.

[0012] Preferably, in step S4, after the PA66 cord is impregnated, the pull-out force H is increased to 286N and the breaking strength is 495.6N.

[0013] By optimizing plasma parameters (power, speed) and impregnation tension (4-10KN), the adhesive force and mechanical properties are balanced, the H-pulling force meets the standard (≥280N), satisfying the requirements of aviation tires, and the breaking strength decreases by only 3% (511N→495.6N), ensuring the integrity of the cord structure.

[0014] An aircraft tire cord is prepared by any one of the methods described in S1-S5, wherein the surface roughness of the cord is Ra≥1.5μm and the pull-out force H at the rubber interface is ≥280N.

[0015] The cord (1) prepared by the preparation method in Example 1 has a surface roughness Ra≥1.5μm and H-pulling force≥280N. The rough surface and chemical bonding work together to solve the problem of film peeling, and the H-pulling force is improved to the level applicable to aircraft tires (≥280N).

[0016] Preferably, the oxygen content on the surface of the cord is 38%-43%.

[0017] Preferably, the surface adhesive film residue rate of the cord is ≥95% after the H-pull-out test.

[0018] Preferably, the breaking strength of the cord is 490-510N and the pull-out force is 280-300N.

[0019] Compared with the prior art, the beneficial effects achieved by the present invention are: First, this invention, through two-step plasma treatment (impurity removal + etching), forms tiny granular protrusions and etched grooves on the surface of PA66 cord (see Figures B / D), increasing the roughness to Ra≥1.5μm, providing mechanical interlocking anchor points; plasma treatment introduces active oxygen groups (oxygen content increases from 14.99% to 40.78%), forming strong chemical bonds with phenolic resin and butadiene-pyridine latex in the RFL impregnation solution; H-pulling force is increased by 38% (from 177.2N to 286N), meeting the requirements of aviation tires (≥280N), and the residual rate of rubber film after impregnation is ≥95% (see Figure F), far higher than untreated cord (where a large amount of rubber film falls off); the interfacial bonding strength is improved, avoiding delamination failure caused by rubber film peeling during tire use.

[0020] Secondly, this invention reduces the breaking strength by only 3% (from 511N to 495.6N), ensuring the integrity of the cord structure; the process parameters (such as plasma power and impregnation tension) are precisely controlled to achieve a synergistic improvement in H-pulling force (280-300N) and breaking strength (490-510N); the use of atmospheric pressure air plasma treatment eliminates the need for a vacuum environment, resulting in low equipment cost and suitability for continuous production; the impregnation solution formulation (resorcinol-formaldehyde-butyridine system) has a stable process and mild reaction conditions (constant temperature of 25℃), making it easy to scale up applications. Attached Figure Description

[0021] Figure 1 The ore body is used for the preparation process of aircraft tire cord. Figure 2 The surface morphology of PA66 without plasma treatment is shown by SEM. Figure 3 The image shows the surface morphology of PA66 after plasma treatment. Figure 4 This image shows the surface adhesive residue of PA66 cord without plasma treatment after an H-pull test. Figure 5 This image shows the surface adhesive residue of PA66 cord after plasma treatment and H-pull test. Figure 6 The XPS spectra before and after plasma treatment are shown (left spectrum is before treatment, right spectrum is after treatment). Figure 7 A comparison chart showing the H-pull force of PA66 cord without plasma treatment and the H-pull force of PA66 cord after plasma treatment. Figure 8 A comparison chart showing the breaking strength of PA66 cord before and after plasma treatment. Figure 9 This is a cross-sectional view of the tire cords of this aircraft.

[0022] The components are: 1. Cord; 2. Rubber; 3. Film. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] This invention provides the following technical solutions: Example 1 Please see Figures 1-9 A method for preparing aircraft tire cord includes the following steps: S1: Surface impurities of PA66 cord are removed using plasma with a power of 30W and a speed of 25mm / s; S2: The surface of the PA66 cord treated in step S1 is etched using plasma with a power of 150W and a speed of 25mm / s. S3: Prepare the impregnation solution, which includes the following components by weight percentage: A phenolic resin solution was obtained by stirring 41.9 parts of deionized water, 0.05 parts of sodium hydroxide, 1.96 parts of resorcinol, and 1.06 parts of formaldehyde at a constant temperature of 25°C for 6 hours. 44.5 parts of butyl pyridine latex, 4.45 parts of 2-vinylpyridine, 3 parts of RF m-methyl solution, and 0.8 parts of ammonia were reacted at a constant temperature of 25°C for 20 hours to obtain RFL impregnation solution; S4: Immerse the PA66 cord treated in step S2 in RFL impregnation solution, controlling the tensile tension to be 4-10KN, the pH value to be 9-10, and the immersion time to be 30 seconds. S5: Dry the PA66 cord after impregnation at 180℃ for 10 minutes.

[0025] The above technical solution involves three main steps: First, a 30W low-power, atmospheric-pressure air plasma is used to rapidly remove oil stains, release agents, and other impurities from the PA66 cord surface, preventing high-temperature damage to the material itself. Second, a 150W high-power treatment is used to ionize air and generate active particles, forming a micron-level rough structure (granular protrusions + grooves) with Ra≥1.5μm on the fiber surface, increasing the specific surface area by approximately 30-50% and significantly improving the mechanical interlocking effect. Third, a phenolic resin solution is used: a resorcinol-formaldehyde system forms a thermosetting resin network under weakly alkaline conditions (pH≈9-10), providing initial bonding strength; and an RFL solution is used: butadiene-pyridine latex (butadiene / acrylonitrile copolymer). The PA66 cord is copolymerized with 2-vinylpyridine, and RF m-methyl ester (resorcinol-formaldehyde condensate) is used as a crosslinking agent. Ammonia water catalyzes the formation of a three-dimensional network structure, which imparts high-temperature aging resistance. In the fourth step, the treated PA66 cord is impregnated in RFL impregnation solution. Tension control (4-10KN) ensures that the fiber bundles are tightly arranged. The pH 9-10 environment promotes resin crosslinking. The short impregnation time of 30 seconds avoids excessive swelling. In the fifth step, rapid drying at 180℃ / 10min is carried out to quickly cure the film and avoid thermal degradation of PA66. Through two-step plasma treatment (impurity removal + surface etching) and RFL impregnation solution with a specific formulation, the surface activity and mechanical interlocking ability of the fiber are enhanced.

[0026] The plasma treatment in steps S1 and S2 is atmospheric pressure air plasma.

[0027] Through the above technical solution, the plasma treatment in steps S1 and S2 is atmospheric pressure air plasma, which can simplify equipment requirements, reduce production costs, eliminate the need for a vacuum environment, and is suitable for industrial continuous production. At the same time, the active oxygen free radicals in the air plasma enhance surface oxidation.

[0028] In step S2, surface etching creates tiny granular protrusions and etched grooves on the surface of the PA66 cord, increasing surface roughness.

[0029] The above technical solution uses high-power (150W) plasma to etch PA66 cords to form a rough surface structure. The rough surface provides a mechanical anchoring effect (Figures B / D), significantly improving the H extraction force. The grooves increase the penetration depth of the impregnation solution and enhance the interfacial bonding strength.

[0030] In step S3, the oxygen content of the RFL impregnation solution is 40.78%, which is formed by the chemical bonding of the surface-active groups after plasma treatment with the impregnation solution.

[0031] Through the above technical solution, the surface active groups (such as hydroxyl and carboxyl groups) of PA66 after plasma treatment form strong chemical bonds with phenolic resin and butadiene-pyridine latex in the impregnation solution. The increased oxygen content (XPS data) indicates enhanced chemical bonding, and the film residue rate is ≥95% (Figure F), thus avoiding interface peeling.

[0032] In step S4, after the PA66 cord is impregnated, the pull-out force is increased to 286N and the breaking strength is 495.6N.

[0033] By optimizing plasma parameters (power, speed) and impregnation tension (4-10KN), the adhesive force and mechanical properties are balanced, the H-pulling force meets the standard (≥280N), which meets the requirements of aviation tires, and the breaking strength decreases by only 3% (511N→495.6N), ensuring the integrity of the cord structure.

[0034] Example 2 Please see Figures 1-9 An aircraft tire cord is prepared by the preparation method in Example 1. The surface roughness of the cord 1 is Ra≥1.5μm, and the H-pulling force at the interface with the rubber 2 is≥280N.

[0035] The oxygen content on the surface of cord 1 is 38%-43%.

[0036] After the H extraction test, the residual rate of the adhesive film 3 on the surface of the cord 1 is ≥95%.

[0037] The breaking strength of cord 1 is 490-510N, and the pull-out force of H is 280-300N.

[0038] Through the above technical solution, the surface roughness Ra of the cord 1 prepared by the preparation method in Example 1 is ≥1.5μm, and the H-pull force is ≥280N. The rough surface and chemical bonding work synergistically to solve the problem of film peeling. The H-pull force is improved to the level applicable to aircraft tires (≥280N). Plasma treatment introduces active oxygen groups, and curing with impregnation solution makes the oxygen content on the surface of cord 1 38%-43%. The oxygen content range ensures stable chemical bonding strength and avoids fiber embrittlement due to excessive oxygen content (>43%). Plasma modification and optimized impregnation process ensure tight adhesion of the adhesive film 3. After H extraction test, the residual rate of adhesive film 3 is ≥95%. The high residual rate of adhesive film 3 indicates strong interfacial bonding, reducing the risk of delamination during tire use and extending life. By optimizing process parameters (such as plasma power and impregnation tension), the cord breaking strength is 490-510N and the H extraction force is 280-300N, balancing its performance. The breaking strength is maintained at the level required for aviation tires (≥490N), and the H extraction force meets the standard with a small fluctuation range, ensuring product consistency.

[0039] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing aircraft tire cord, characterized in that, Includes the following steps: S1: Surface impurities of PA66 cord are removed using plasma with a power of 30W and a speed of 25mm / s; S2: The surface of the PA66 cord treated in step S1 is etched using plasma with a power of 150W and a speed of 25mm / s. S3: Prepare the impregnation solution, wherein the impregnation solution comprises the following components by weight percentage: A phenolic resin solution was obtained by stirring at a constant temperature of 25°C for 6 hours with 41.9 parts deionized water, 0.05 parts sodium hydroxide, 1.96 parts resorcinol, and 1.06 parts formaldehyde. 44.5 parts of butyl pyridine latex, 4.45 parts of 2-vinylpyridine, 3 parts of RF m-methyl solution, and 0.8 parts of ammonia were reacted at a constant temperature of 25°C for 20 hours to obtain RFL impregnation solution; S4: Immerse the PA66 cord treated in step S2 in the RFL impregnation solution, controlling the tensile tension to be 4-10KN, the pH value to be 9-10, and the immersion time to be 30 seconds. S5: Dry the PA66 cord after impregnation at 180℃ for 10 minutes.

2. The method for preparing aircraft tire cord according to claim 1, characterized in that: The plasma treatment in steps S1 and S2 is atmospheric pressure air plasma.

3. The method for preparing aircraft tire cord according to claim 1, characterized in that: In step S2, surface etching creates tiny granular protrusions and etched grooves on the surface of the PA66 cord, increasing surface roughness.

4. The method for preparing aircraft tire cord according to claim 1, characterized in that: In step S3, the oxygen content of the RFL impregnation solution is 40.78%, which is formed by the chemical bonding of the surface-active groups after plasma treatment with the impregnation solution.

5. The method for preparing aircraft tire cord according to claim 1, characterized in that... In step S4, after the PA66 cord is impregnated, the pull-out force H increases to 286N and the breaking strength is 495.6N.

6. An aircraft tire cord, characterized in that, The cord (1) is prepared by the method described in any one of claims 1-5, and the surface roughness of the cord (1) is Ra≥1.5μm, and the H-pulling force at the interface with the rubber (2) is ≥280N.

7. The aircraft tire cord according to claim 6, characterized in that: The oxygen content on the surface of the cord (1) is 38%-43%.

8. The aircraft tire cord according to claim 6, characterized in that: The surface adhesive film (3) of the cord (1) after the H extraction test has a residual rate of ≥95%.

9. The aircraft tire cord according to claim 6, characterized in that: The breaking strength of the cord (1) is 490-510N, and the pull-out force is 280-300N.

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