A porous phenolic cloth composite material, a preparation method thereof, a retainer and a bearing

Abstract

The present application relates to a kind of porous phenolic cloth composite and its preparation method, retainer, bearing, belong to bearing retainer technical field.The preparation method of the porous phenolic cloth composite of the present application, cotton cloth is respectively dipped in foaming agent solution mainly by N,N'-dinitrosopentamethylene tetramine, urea and solvent, mainly by phenolic resin, polytetrafluoroethylene powder and organic solvent Composed of polymer glue solution, then successively winding forming, solidification, obtain porous phenolic cloth composite.The preparation method of the porous phenolic cloth composite of the present application has higher product qualification rate, and the porous phenolic cloth composite prepared has higher tensile strength, lower friction coefficient and smaller wear amount, can satisfy the need of high speed, long life and high reliability of machine tool spindle bearing.

Description

Technical Field

[0001] This invention relates to a porous phenolic fabric composite material, its preparation method, a cage, and a bearing, belonging to the technical field of bearing cages. Background Technology

[0002] Machine tool spindle bearings operate at high speeds; generally, the rotational performance of machine tool spindle bearings is... m n(d m n (equal to the product of the bearing pitch circle diameter and the rotational speed) has a value greater than 1.0 × 10⁻⁶. 6 Traditional bakelite cages, operating at speeds of mm.r / min, suffer from drawbacks such as high temperature rise, high noise, and poor lifespan and reliability. This is mainly due to the insufficient mechanical strength and friction performance of traditional bakelite cages, resulting in a large amount of wear debris containing hard phenolic resin particles, which leads to lubrication failure.

[0003] Porous phenolic resin laminated cages, due to their internal micropores, allow lubricating oil to be immersed in the cage. During bearing operation, the lubricating oil can be released outwards, and excess lubricating oil can be absorbed, providing long-term, good, and continuous lubrication for the bearing. Applying porous phenolic resin laminated cages to high-speed precision machine tool spindle bearings is an effective way to solve the aforementioned problems. For example, Chinese patent document CN101294603A discloses a porous phenolic resin laminated cage material and manufacturing method for rolling bearings. The method involves first pre-impregnating the laminated cage material with a foaming agent, then using the foaming agent to create pores during resin curing. This manufacturing method involves five processes: phenolic resin preparation, foaming agent preparation, impregnation of cotton cloth with the foaming agent and phenolic resin, winding and molding, and post-curing, resulting in a high-porosity, oil-containing porous phenolic resin laminated cage material. Chinese patent document CN113121951B discloses a porous phenolic resin fabric tube, its preparation method, and its application. The preparation method includes the following steps: cotton is placed in hydrogenated silicone oil for a first impregnation, and then baked to obtain silicone oil-impregnated cotton cloth; the silicone oil-impregnated cotton is placed in a phenolic resin solution for a second impregnation, and then wound to obtain a fabric tube; the fabric tube is cured to obtain a cured fabric tube; the hydrogenated silicone oil in the cured fabric tube is removed to obtain a porous phenolic resin fabric tube. The porous phenolic resin fabric tube prepared by this invention has interconnected channels and high porosity, enabling the formation of continuous oil storage space, meeting the high oil content requirement of bearing cages; moreover, the porous phenolic resin fabric tube prepared by this invention does not have air bubbles dispersed in the phenolic matrix, which can improve the mechanical properties of the phenolic resin fabric tube. However, the preparation method of this porous phenolic fabric tube requires acetone pretreatment of the cotton cloth and complex operations to remove the hydrogenated silicone oil in the cured fabric tube, which complicates the production process and increases production costs. Moreover, the cotton cloth and phenolic resin in the porous phenolic fabric tube prepared by this patent are separated. When processed into a cage, the surface of the finished cage is either pure phenolic resin or oil-impregnated cotton cloth. Neither of these states is conducive to the actual operation of the bearing. Pure phenolic resin does not contain oil and has poor friction performance, while oil-impregnated cotton cloth does not contain resin and has poor wear resistance.

[0004] Existing porous phenolic fabric composite materials are mainly used in aerospace bearings such as gyroscope bearings and large-size thin-walled bearings. The d-axis of gyroscope bearings and large-size thin-walled bearings... m The value of n is generally less than 3.0 × 10. 5 mm.r / min, when used for d m When the n value is large, the material properties still have some shortcomings, such as low strength, large friction coefficient and insufficient wear resistance. At the same time, when applied in the civilian field, it is necessary to further improve the finished product qualification rate of porous phenolic cloth composite material and reduce production costs. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing porous phenolic fabric composite materials, which can solve the problems of low strength, high friction coefficient and insufficient wear resistance of currently prepared porous phenolic fabric composite materials.

[0006] The second objective of this invention is to provide a porous phenolic fabric composite material that can solve the problems of low strength and insufficient wear resistance of current porous phenolic fabric composite materials.

[0007] The third objective of this invention is to provide a cage that can solve the problems of low strength and insufficient wear resistance of cages made of porous phenolic fabric composite materials.

[0008] The fourth objective of this invention is to provide a bearing that can solve the problems of low strength and insufficient wear resistance of the cage in current bearings.

[0009] To achieve the above objectives, the technical solution adopted in the preparation method of the porous phenolic fabric composite material of the present invention is as follows:

[0010] A method for preparing a porous phenolic fabric composite material includes the following steps:

[0011] (1) The fabric is impregnated with a foaming agent solution and then baked to obtain a fabric impregnated with a foaming agent;

[0012] (2) The fabric impregnated with the foaming agent is impregnated with the polymer adhesive solution and baked to obtain a prepreg fabric; the polymer adhesive solution is mainly composed of phenolic resin, polytetrafluoroethylene powder and organic solvent; the average particle size D of the polytetrafluoroethylene powder is... 50 ≤3μm;

[0013] (3) The prepreg fabric is wound and cured in sequence to obtain a porous phenolic fabric composite material.

[0014] The preparation method of the porous phenolic fabric composite material of the present invention has a high product qualification rate. The prepared porous phenolic fabric composite material has high tensile strength, low coefficient of friction and low wear, which can meet the requirements of high speed, long service life and high reliability of machine tool spindle bearings.

[0015] It is understood that any fabric used in the production of porous phenolic fabric tubes (porous phenolic fabric composite materials) is suitable for this invention. Preferably, the fabric is cotton. To ensure that the prepared porous phenolic fabric composite material has high strength, high-count cotton fabric is used in this invention; preferably, the cotton fabric has a count of 60 to 120.

[0016] Preferably, in step (1), the foaming agent solution mainly consists of a foaming agent and a solvent.

[0017] It is understood that the foaming agents used in the production of porous phenolic fabric tubes (porous phenolic fabric composite materials) are all applicable to this invention.

[0018] Preferably, in step (1), the foaming agent comprises N,N'-dinitrospentamethylenetetramine and a foaming co-agent. Preferably, the foaming co-agent is urea. Preferably, in step (1), the mass ratio of N,N'-dinitrospentamethylenetetramine to the foaming co-agent is (3-5):1.

[0019] Preferably, in step (1), the mass fraction of N,N'-dinitrospentamethylenetetramine in the foaming agent solution is 1.3-2.5%.

[0020] Preferably, in step (1), the solvent includes an alcohol solvent and a ketone solvent. Preferably, the alcohol solvent is ethanol. Preferably, the ketone solvent is acetone. Preferably, the mass ratio of the alcohol solvent to the ketone solvent in the foaming agent solution is 1:(8-10).

[0021] Preferably, in step (1), the foaming agent solution is prepared by mixing N,N'-dinitrospentamethylenetetramine solution and urea solution; the N,N'-dinitrospentamethylenetetramine solution is composed of N,N'-dinitrospentamethylenetetramine and acetone; the urea solution is composed of urea and ethanol.

[0022] Preferably, in step (1), the impregnation rate is 1 to 2 m / min.

[0023] Preferably, in step (1), the baking temperature is 70-80°C. It is understood that baking is generally carried out in a dipping machine, and the baking time can be determined by setting the dipping speed and baking temperature of the equipment. In step (1), the purpose of baking is to allow the organic solvent to evaporate as much as possible, leaving N,N'-dinitrospentamethylenetetramine and urea evenly on the cotton fabric.

[0024] Preferably, in step (2), the gel time of the phenolic resin is 150-200 s. The gel time can reflect the molecular weight of the resin. When the gel time is in the range of 150-200 s, the molecular weight of the phenolic resin is appropriate, neither too large nor too small. This can avoid poor wetting or excessive resin flow when impregnating cotton fabric. At the same time, the porosity can be controlled by influencing the foaming process.

[0025] In this invention, the gel time test method is carried out in accordance with the provisions of standard GB / T 32788.1-2016.

[0026] Preferably, in step (2), the phenolic resin is prepared by a method comprising the following steps: heating a mixture mainly composed of phenol, formaldehyde, an alkaline catalyst, and water to 40–60°C and holding for 20–60 min, then heating to 65–85°C and holding for 40–120 min, followed by dehydration treatment to obtain the phenolic resin. For example, in step (2), the phenolic resin is prepared by a method comprising the following steps: heating a mixture mainly composed of phenol, formaldehyde, an alkaline catalyst, and water to 40–60°C and holding for 20–60 min, then heating to 65–85°C and holding for 50–120 min, followed by dehydration treatment to obtain the phenolic resin.

[0027] Preferably, in step (2), the molar ratio of phenol to formaldehyde is 1:(1 to 1.1). For example, in step (2), the molar ratio of phenol to formaldehyde is 1:1.

[0028] Preferably, in step (2), the mixture is prepared by mixing phenol, formaldehyde solution, and ammonia. Preferably, in step (2), the mass ratio of phenol to ammonia is 100:(1-5). Preferably, the mass fraction of the formaldehyde solution is 35-40%. Preferably, the mass fraction of the ammonia is 25-28%. Excessive ammonia will lead to a violent reaction, making it difficult to control and resulting in excessively large resin molecular weight, which is detrimental to impregnation and foaming; insufficient ammonia will easily lead to incomplete reaction, resulting in substandard product strength.

[0029] Preferably, in step (2), the dehydration process is carried out under vacuum conditions, and the temperature used for the dehydration process is 50-70°C.

[0030] During dehydration, the difference between the amount of water obtained from dehydration and the theoretical amount of water can be observed. Alternatively, dehydration can be continued until no more water is produced in the system. Preferably, in step (2), the mass of the water obtained from the dehydration process is 75% of the total mass of the phenol and formaldehyde.

[0031] Preferably, in step (2), the organic solvent is an alcohol solvent. For example, the organic solvent is ethanol.

[0032] Preferably, the average particle size D of the polytetrafluoroethylene powder is... 50 The particle size is 0.5–3 μm. For example, the average particle size D of the polytetrafluoroethylene powder is... 50 The particle size is 0.8–3 μm. Preferably, the mass of the polytetrafluoroethylene powder is 3–30% of the mass of the phenolic resin. Excessive amounts of polytetrafluoroethylene powder or excessively large particle sizes result in poor dispersion in the phenolic resin, easy sedimentation, and the tendency to float on the surface of the cotton fabric during impregnation, leading to poor modification effects. Insufficient amounts of polytetrafluoroethylene powder result in poor performance improvement.

[0033] Preferably, in step (2), the mass of the organic solvent is 40-50% of the mass of the phenolic resin. The organic solvent is used to adjust the viscosity of the adhesive solution. If the viscosity is too high, the product is prone to separation; if the viscosity is too low, it will stick to the rollers during winding, resulting in low production efficiency.

[0034] Preferably, in step (2), the polymer solution is prepared by mixing a polytetrafluoroethylene (PTFE) powder dispersion and a phenolic resin. Preferably, the PTFE powder dispersion is prepared by mixing PTFE powder and an organic solvent under ultrasonic conditions. Preferably, the PTFE powder dispersion is prepared by a method comprising the following steps: placing PTFE powder in an organic solvent and then subjecting it to ultrasonic dispersion. Preferably, in step (2), the frequency of the ultrasonication is 30–40 kHz; and the ultrasonic dispersion time is 20–40 min.

[0035] Preferably, in step (2), the impregnation speed is 1–3 m / min. Preferably, in step (2), the baking temperature is 90–120°C. In step (2), the baking mainly removes the solvent and pre-cures the resin.

[0036] In this invention, the winding process involves winding the prepreg fabric onto a tube winding machine using a hot roller pressing method.

[0037] Preferably, in step (3), the rolling pressure used in the winding process is 0.1–0.5 MPa, and the rolling temperature is 90–120°C. For example, in step (3), the rolling pressure used in the winding process is 0.2–0.5 MPa, and the rolling temperature is 90–120°C. Excessive rolling pressure will cause the cotton fabric to tear; insufficient rolling pressure will result in a loose roll, low product density, and low strength. Excessive rolling temperature will cause excessive resin overflow and may also lead to premature cross-linking and curing; insufficient rolling temperature will prevent the cotton fabric from adhering properly, resulting in defects in the product.

[0038] Preferably, in step (3), the curing method includes the following steps: heating the prepreg fabric after winding to 80-100°C and keeping it warm for 1-2 hours, and then heating it to 130-150°C and keeping it warm for 4-9 hours.

[0039] The technical solution adopted in the porous phenolic fabric composite material of the present invention is as follows:

[0040] A porous phenolic fabric composite material prepared by the method described above.

[0041] The porous phenolic fabric composite material of the present invention has high tensile strength, low coefficient of friction and low wear, which can meet the requirements of high speed, long service life and high reliability of machine tool spindle bearings.

[0042] The technical solution adopted by the cage of the present invention is as follows:

[0043] A retainer made of a porous phenolic fabric composite material as described above.

[0044] The cage of the present invention has high tensile strength, low coefficient of friction and low wear, which can meet the requirements of high speed, long service life and high reliability of machine tool spindle bearings.

[0045] The technical solution adopted by the bearing of this invention is as follows:

[0046] A bearing comprising a cage as described above.

[0047] Using a cage made of the porous phenolic fabric composite material of the present invention in a bearing can meet the requirements of high speed, long service life and high reliability of the bearing. Detailed Implementation

[0048] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0049] I. Specific embodiments of the preparation method of the porous phenolic fabric composite material of the present invention are as follows:

[0050] Example 1

[0051] The preparation method of the porous phenolic fabric composite material in this embodiment specifically includes the following steps:

[0052] (1) The desized cotton fabric of 80 count yarn was impregnated with a foaming agent solution on an impregnation machine and then baked to obtain cotton fabric impregnated with foaming agent; the impregnation speed was 1 m / min and the baking temperature was 75℃; the foaming agent solution was prepared by mixing an acetone solution of N,N'-dinitrospentamethylenetetramine and an ethanol solution of urea. In the foaming agent solution, the mass ratio of N,N'-dinitrospentamethylenetetramine to urea was 4:1, the mass fraction of N,N'-dinitrospentamethylenetetramine was 1.65%, and the mass ratio of ethanol to acetone was 1:8;

[0053] (2) The cotton fabric impregnated with foaming agent is impregnated with polymer adhesive using an impregnation machine and then baked to obtain prepreg fabric; the impregnation speed is 3m / min and the baking temperature is 100℃.

[0054] The polymeric adhesive is prepared by a method comprising the following steps:

[0055] S1. A mixture prepared by mixing phenol, formaldehyde solution, and ammonia is added to a reaction vessel. The mixture in the reaction vessel is first heated to 60°C and held for 60 minutes, then heated to 70°C and held for 70 minutes. The reaction is then stopped. When the temperature of the material in the reaction vessel drops to 60°C, vacuum dehydration is performed. Dehydration is stopped when the amount of dehydration is close to the theoretical amount of dehydration (the mass of water removed is 75% of the sum of the masses of phenol and formaldehyde), and phenolic resin is obtained. The gel time of the phenolic resin is measured to be 192 seconds. The molar ratio of formaldehyde in the phenol and formaldehyde solution is 1:1, the mass fraction of the formaldehyde solution is 40%, the mass fraction of the ammonia is 28%, and the mass ratio of phenol to ammonia is 100:2.

[0056] S2, polytetrafluoroethylene micro powder (average particle size D) 50 =0.5μm) was placed in anhydrous ethanol and ultrasonically dispersed evenly (the ultrasonic frequency was 30kHz and the ultrasonic dispersion time was 25min) to obtain a polytetrafluoroethylene powder dispersion; the mass of polytetrafluoroethylene micro powder was 10% of the mass of phenolic resin obtained in step S1, and the mass of anhydrous ethanol was 45% of the mass of phenolic resin obtained in step S1.

[0057] Then, the polytetrafluoroethylene powder dispersion was added to the phenolic resin obtained in step S1 and stirred evenly to obtain a polymer solution.

[0058] (3) The prepreg fabric is wound into shape on a tube winding machine using a hot roll pressing method. Then, the wound prepreg fabric is placed in a sintering furnace for curing. The curing process involves first heating the wound prepreg fabric to 90°C and holding it at that temperature for 1 hour, and then heating it to 150°C and holding it at that temperature for 4 hours. After curing, a porous phenolic fabric composite material is obtained. The roll pressing pressure used in the winding process is 0.3 MPa, and the roll pressing temperature is 110°C.

[0059] Example 2

[0060] The preparation method of the porous phenolic fabric composite material in this embodiment specifically includes the following steps:

[0061] (1) A desized cotton fabric of 100 count yarn was impregnated with a foaming agent solution on an impregnation machine and then baked to obtain a cotton fabric impregnated with a foaming agent; the impregnation speed was 1 m / min and the baking temperature was 70℃; the foaming agent solution was prepared by mixing an acetone solution of N,N'-dinitrospentamethylenetetramine and an ethanol solution of urea. In the foaming agent solution, the mass ratio of N,N'-dinitrospentamethylenetetramine to urea was 5:1, the mass fraction of N,N'-dinitrospentamethylenetetramine was 1.30%, and the mass ratio of ethanol to acetone was 1:9;

[0062] (2) The cotton fabric impregnated with foaming agent is impregnated with polymer adhesive using an impregnation machine and then baked to obtain prepreg; the impregnation speed is 3m / min and the baking temperature is 90℃.

[0063] The polymeric adhesive is prepared by a method comprising the following steps:

[0064] S1. A mixture prepared by mixing phenol, formaldehyde solution, and ammonia is added to a reaction vessel. The mixture in the reaction vessel is first heated to 60°C and held for 50 minutes, then heated to 85°C and held for 60 minutes. The reaction is then stopped. When the temperature of the material in the reaction vessel drops to 70°C, vacuum dehydration is performed. Dehydration is stopped when the amount of dehydration is close to the theoretical amount of dehydration (the mass of water removed is 75% of the sum of the masses of phenol and formaldehyde), and phenolic resin is obtained. The gel time of the phenolic resin is determined to be 200 seconds. The molar ratio of formaldehyde in the phenol and formaldehyde solution is 1:1, the mass fraction of the formaldehyde solution is 35%, the mass fraction of the ammonia is 25%, and the mass ratio of phenol to ammonia is 100:1.

[0065] S2, polytetrafluoroethylene micro powder (average particle size D) 50 =2.3μm) was placed in anhydrous ethanol and ultrasonically dispersed evenly (ultrasonic frequency of 30kHz, ultrasonic dispersion time of 20min) to obtain polytetrafluoroethylene powder dispersion; the mass of polytetrafluoroethylene micro powder was 20% of the mass of phenolic resin obtained in step S1, and the mass of anhydrous ethanol was 40% of the mass of phenolic resin obtained in step S1.

[0066] Then, the polytetrafluoroethylene powder dispersion was added to the phenolic resin obtained in step S1 and stirred evenly to obtain a polymer solution.

[0067] (3) The prepreg fabric is wound into shape on a tube winding machine using a hot roll pressing method. Then, the wound prepreg fabric is placed in a sintering furnace for curing. The curing process involves first heating the wound prepreg fabric to 80°C and holding it at that temperature for 2 hours, and then heating it to 140°C and holding it at that temperature for 5 hours. After curing, a porous phenolic fabric composite material is obtained. The roll pressing pressure used in the winding process is 0.1 MPa, and the roll pressing temperature is 100°C.

[0068] Example 3

[0069] The preparation method of the porous phenolic fabric composite material in this embodiment specifically includes the following steps:

[0070] (1) The desized cotton fabric of 120 count yarn was impregnated with a foaming agent solution on an impregnation machine and then baked to obtain cotton fabric impregnated with foaming agent; the impregnation speed was 1 m / min and the baking temperature was 70℃; the foaming agent solution was prepared by mixing an acetone solution of N,N'-dinitrospentamethylenetetramine and an ethanol solution of urea. In the foaming agent solution, the mass ratio of N,N'-dinitrospentamethylenetetramine to urea was 3:1, the mass fraction of N,N'-dinitrospentamethylenetetramine was 2.05%, and the mass ratio of ethanol to acetone was 1:10;

[0071] (2) The cotton fabric impregnated with foaming agent is impregnated with polymer adhesive using an impregnation machine and then baked to obtain prepreg; the impregnation speed is 2m / min and the baking temperature is 110℃.

[0072] The polymeric adhesive is prepared by a method comprising the following steps:

[0073] S1. A mixture prepared by mixing phenol, formaldehyde solution, and ammonia is added to a reaction vessel. The mixture in the reaction vessel is first heated to 50°C and held for 40 minutes, then heated to 70°C and held for 40 minutes. The reaction is then stopped. When the temperature of the material in the reaction vessel drops to 55°C, vacuum dehydration is performed. Dehydration is stopped when the amount of dehydration is close to the theoretical amount of dehydration (the mass of water removed is 75% of the sum of the masses of phenol and formaldehyde), and phenolic resin is obtained. The gel time of the phenolic resin is measured to be 175 seconds. The molar ratio of formaldehyde in the phenol and formaldehyde solution is 1:1, the mass fraction of the formaldehyde solution is 35%, the mass fraction of ammonia is 25%, and the mass ratio of phenol to ammonia is 100:3.

[0074] S2, polytetrafluoroethylene micro powder (average particle size D) 50 =1.7μm) was placed in anhydrous ethanol and ultrasonically dispersed evenly (ultrasonic frequency of 30kHz, ultrasonic dispersion time of 30min) to obtain polytetrafluoroethylene powder dispersion; the mass of polytetrafluoroethylene micro powder was 30% of the mass of phenolic resin obtained in step S1, and the mass of anhydrous ethanol was 50% of the mass of phenolic resin obtained in step S1.

[0075] Then, the polytetrafluoroethylene powder dispersion was added to the phenolic resin obtained in step S1 and stirred evenly to obtain a polymer solution.

[0076] (3) The prepreg fabric is wound into shape on a tube winding machine using a hot roll pressing method. Then, the wound prepreg fabric is placed in a sintering furnace for curing. The curing process involves first heating the wound prepreg fabric to 90°C and holding it at that temperature for 2 hours, and then heating it to 140°C and holding it at that temperature for 6 hours. After curing, a porous phenolic fabric composite material is obtained. The roll pressing pressure used in the winding process is 0.4 MPa, and the roll pressing temperature is 120°C.

[0077] Example 4

[0078] The preparation method of the porous phenolic fabric composite material in this embodiment specifically includes the following steps:

[0079] (1) The desized cotton fabric of 60 count yarn was impregnated with a foaming agent solution on an impregnation machine and then baked to obtain cotton fabric impregnated with foaming agent; the impregnation speed was 1 m / min and the baking temperature was 80℃; the foaming agent solution was prepared by mixing an acetone solution of N,N'-dinitrospentamethylenetetramine and an ethanol solution of urea. In the foaming agent solution, the mass ratio of N,N'-dinitrospentamethylenetetramine to urea was 4:1, the mass fraction of N,N'-dinitrospentamethylenetetramine was 2.50%, and the mass ratio of ethanol to acetone was 1:8;

[0080] (2) The cotton fabric impregnated with foaming agent is impregnated with polymer adhesive using an impregnation machine and then baked to obtain prepreg fabric; the impregnation speed is 1m / min and the baking temperature is 120℃;

[0081] The polymeric adhesive is prepared by a method comprising the following steps:

[0082] S1. A mixture prepared by mixing phenol, formaldehyde solution, and ammonia is added to a reaction vessel. The mixture in the reaction vessel is first heated to 40°C and held for 20 minutes, then heated to 65°C and held for 60 minutes. The reaction is then stopped. When the temperature of the material in the reaction vessel drops to 55°C, vacuum dehydration is performed. Dehydration is stopped when the amount of dehydration is close to the theoretical amount of dehydration (the mass of water removed is 75% of the sum of the masses of phenol and formaldehyde), and phenolic resin is obtained. The gel time of the phenolic resin is determined to be 150 seconds. The molar ratio of formaldehyde in the phenol and formaldehyde solution is 1:1, the mass fraction of the formaldehyde solution is 40%, the mass fraction of the ammonia is 28%, and the mass ratio of phenol to ammonia is 100:5.

[0083] S2, polytetrafluoroethylene micro powder (average particle size D) 50 =1.3μm) was placed in anhydrous ethanol and ultrasonically dispersed evenly (ultrasonic frequency of 40kHz, ultrasonic dispersion time of 40min) to obtain polytetrafluoroethylene powder dispersion; the mass of polytetrafluoroethylene micro powder was 3% of the mass of phenolic resin obtained in step S1, and the mass of anhydrous ethanol was 50% of the mass of phenolic resin obtained in step S1.

[0084] Then, the polytetrafluoroethylene powder dispersion was added to the phenolic resin obtained in step S1 and stirred evenly to obtain a polymer solution.

[0085] (3) The prepreg fabric is wound into shape on a tube winding machine using a hot roll pressing method. Then, the wound prepreg fabric is placed in a sintering furnace for curing. The curing process involves first heating the wound prepreg fabric to 80°C and holding it at that temperature for 2 hours, and then heating it to 130°C and holding it at that temperature for 8 hours. After curing, a porous phenolic fabric composite material is obtained. The roll pressing pressure used in the winding process is 0.4 MPa, and the roll pressing temperature is 90°C.

[0086] Example 5

[0087] The preparation method of the porous phenolic fabric composite material in this embodiment specifically includes the following steps:

[0088] (1) A desized cotton fabric of 100 count yarn was impregnated with a foaming agent solution on an impregnation machine and then baked to obtain a cotton fabric impregnated with a foaming agent; the impregnation speed was 2 m / min and the baking temperature was 75℃; the foaming agent solution was prepared by mixing an acetone solution of N,N'-dinitrospentamethylenetetramine and an ethanol solution of urea. In the foaming agent solution, the mass ratio of N,N'-dinitrospentamethylenetetramine to urea was 5:1, the mass fraction of N,N'-dinitrospentamethylenetetramine was 1.95%, and the mass ratio of ethanol to acetone was 1:9;

[0089] (2) The cotton fabric impregnated with foaming agent is impregnated with polymer adhesive using an impregnation machine and then baked to obtain prepreg; the impregnation speed is 2m / min and the baking temperature is 120℃.

[0090] The polymeric adhesive is prepared by a method comprising the following steps:

[0091] S1. A mixture prepared by mixing phenol, formaldehyde solution, and ammonia is added to a reaction vessel. The mixture in the reaction vessel is first heated to 40°C and held for 20 minutes, then heated to 65°C and held for 120 minutes. The reaction is then stopped. When the temperature of the material in the reaction vessel drops to 50°C, vacuum dehydration is performed. Dehydration is stopped when the amount of dehydration is close to the theoretical amount of dehydration (the mass of water removed is 75% of the sum of the masses of phenol and formaldehyde), and phenolic resin is obtained. The gel time of the phenolic resin is measured to be 168 s; the molar ratio of formaldehyde in phenol and formaldehyde solution is 1:1; the mass fraction of formaldehyde solution is 38%; the mass fraction of ammonia is 27%; and the mass ratio of phenol to ammonia is 100:1.

[0092] S2, polytetrafluoroethylene micro powder (average particle size D) 50 =3μm) was placed in anhydrous ethanol and ultrasonically dispersed evenly (ultrasonic frequency of 35kHz, ultrasonic dispersion time of 30min) to obtain polytetrafluoroethylene powder dispersion; the mass of polytetrafluoroethylene micro powder was 5% of the mass of phenolic resin obtained in step S1, and the mass of anhydrous ethanol was 40% of the mass of phenolic resin obtained in step S1.

[0093] Then, the polytetrafluoroethylene powder dispersion was added to the phenolic resin obtained in step S1 and stirred evenly to obtain a polymer solution.

[0094] (3) The prepreg fabric is wound into shape on a tube winding machine using a hot roll pressing method. Then, the wound prepreg fabric is placed in a sintering furnace for curing. The curing process involves first heating the wound prepreg fabric to 100°C and holding it at that temperature for 1 hour, and then heating it to 130°C and holding it at that temperature for 9 hours. After curing, a porous phenolic fabric composite material is obtained. The roll pressing pressure used in the winding process is 0.5 MPa, and the roll pressing temperature is 100°C.

[0095] Comparative Example 1

[0096] The difference between the preparation method of the porous phenolic fabric composite material in this comparative example and the preparation method of the porous phenolic fabric composite material in Example 1 is that, in the preparation method of the porous phenolic fabric composite material in this comparative example, when preparing the phenolic resin used in step (2), the mixture in the reaction vessel is first heated to 70°C and kept at that temperature for 60 min, and then heated to 70°C and kept at that temperature for 70 min, and the reaction is stopped. Other operations are the same as in Example 1.

[0097] Comparative Example 2

[0098] The difference between the preparation method of the porous phenolic fabric composite material in this comparative example and the preparation method of the porous phenolic fabric composite material in Example 5 is that, in the preparation method of the porous phenolic fabric composite material in this comparative example, when preparing the phenolic resin used in step (2), the mixture in the reaction vessel is first heated to 38°C and kept at that temperature for 20 min, and then heated to 65°C and kept at that temperature for 120 min, and the reaction is stopped. Other operations are the same as in Example 1.

[0099] Comparative Example 3

[0100] The difference between the preparation method of the porous phenolic fabric composite material in this comparative example and the preparation method of the porous phenolic fabric composite material in Example 5 is that, in the preparation method of the porous phenolic fabric composite material in this comparative example, when preparing the phenolic resin used in step (2), the mixture in the reaction vessel is first heated to 40°C and kept at that temperature for 20 minutes, and then heated to 62°C and kept at that temperature for 120 minutes before stopping the reaction. Other operations are the same as in Example 1.

[0101] Comparative Example 4

[0102] The difference between the preparation method of the porous phenolic fabric composite material in this comparative example and the preparation method of the porous phenolic fabric composite material in Example 1 is that, in the preparation method of the porous phenolic fabric composite material in this comparative example, when preparing the phenolic resin used in step (2), the mixture in the reaction vessel is first heated to 60°C and kept at that temperature for 50 min, and then heated to 90°C and kept at that temperature for 60 min, and the reaction is stopped. Other operations are the same as in Example 1.

[0103] Comparative Example 5

[0104] The difference between the preparation method of the porous phenolic fabric composite material in this comparative example and the preparation method of the porous phenolic fabric composite material in Example 5 lies only in the average particle size D of the polytetrafluoroethylene micropowder used in the preparation method of the porous phenolic fabric composite material in this comparative example. 50 =5μm.

[0105] Comparative Example 6

[0106] The difference between the preparation method of the porous phenolic fabric composite material in this comparative example and the preparation method of the porous phenolic fabric composite material in Example 1 lies only in the average particle size D of the polytetrafluoroethylene micropowder used in the preparation method of the porous phenolic fabric composite material in this comparative example. 50 =10nm.

[0107] Comparative Example 7

[0108] The difference between the preparation method of the porous phenolic fabric composite material in this comparative example and the preparation method of the porous phenolic fabric composite material in Example 1 is only that the polymer adhesive used in the preparation method of the porous phenolic fabric composite material in this comparative example is obtained by a method including the following steps:

[0109] S1, Step S1 in the preparation method of the porous phenolic fabric composite material of this comparative example is the same as Step S1 in the preparation method of the porous phenolic fabric composite material of Example 1.

[0110] S2, polytetrafluoroethylene micro powder (average particle size D) 50 =0.8μm) and anhydrous ethanol were added to the phenolic resin obtained in step S1, and after being ultrasonically dispersed evenly (the ultrasonic dispersion time was 10 times that in the preparation method of porous phenolic cloth composite material in Example 1, and the ultrasonication was carried out under sealed conditions to prevent ethanol evaporation), a polymer adhesive was obtained.

[0111] Comparative Example 8

[0112] The preparation method of the porous phenolic cloth composite material in this comparative example is in accordance with the manufacturing method of the porous phenolic cloth laminated cage material for sensitive bearings in Example 1 of Chinese Patent Document CN100570165C.

[0113] Comparative Example 9

[0114] The difference between the preparation method of the porous phenolic fabric composite material in this comparative example and the preparation method of the porous phenolic fabric composite material in Example 1 is that the mass fraction of N,N'-dinitrospentamethylenetetramine and urea in the foaming agent solution used in step (1) of the preparation method of the porous phenolic fabric composite material in this comparative example is 0.

[0115] II. Specific embodiments of the porous phenolic fabric composite material of the present invention are as follows:

[0116] The porous phenolic fabric composite material of this embodiment was prepared by any of the preparation methods of porous phenolic fabric composite materials in Examples 1-5, and will not be described again here.

[0117] III. Specific embodiments of the cage of the present invention are as follows:

[0118] The retainer in this embodiment is made of porous phenolic fabric composite material prepared by any of the methods in Examples 1-5, and will not be described in detail here.

[0119] IV. Specific embodiments of the bearing of the present invention are as follows:

[0120] The bearing of this embodiment includes a cage made of porous phenolic fabric composite material prepared by any of the preparation methods of porous phenolic fabric composite materials in Examples 1-5.

[0121] Experimental Example

[0122] To evaluate the performance of the porous phenolic fabric composites prepared in Examples 1-5 and Comparative Examples 1-9, the radial tensile strength, average pore size, porosity, coefficient of friction, frictional wear, and product qualification rate of the porous phenolic fabric composites prepared in Examples 1-5 and Comparative Examples 1-9 were tested respectively. The radial tensile strength was tested according to the method in standard JB / T4037-2019; the average pore size and porosity were tested according to the method in standard GB / T21650.1-2008; the coefficient of friction and friction wear (oil) were tested according to the method in standard ASTM G133-2005, with the following parameters: load 20N, frequency 20Hz, and time 1h. The product qualification rate was tested as follows: 50 porous phenolic fabric composite material samples were prepared repeatedly according to the same preparation method, and then observed under a microscope at a magnification of 20x. When the sample showed defects such as delamination, holes, or spalling, the sample quality was considered unqualified; when the sample did not show defects such as delamination, holes, or spalling, the sample quality was considered qualified. The performance test results of the porous phenolic fabric composite materials prepared in Examples 1-5 and Comparative Examples 1-9 are shown in Table 1.

[0123] Table 1. Properties of the porous phenolic fabric composites prepared in Examples 1-5 and Comparative Examples 1-9

[0124]

[0125] As shown in Table 1, compared with the porous phenolic cloth composite material prepared in Comparative Example 8, the porous phenolic cloth composite materials prepared in Examples 1-5 have improved friction properties and significantly enhanced mechanical strength. The radial tensile strength of the porous phenolic cloth composite material prepared in Example 1 increased by 117%, and the porous phenolic cloth composite materials prepared in Examples 1-5 have a high pass rate. They can be widely used in machine tool spindle bearings and other fields to meet the development needs of high-speed precision bearings in my country, with significant economic and social benefits.

Claims

1. A method for producing a porous phenolic cloth composite material, characterized by, The method comprises the following steps: (1) dipping cloth into a foaming agent solution, and baking to obtain cloth impregnated with foaming agent; (2) impregnate the cloth impregnated with the foaming agent with a polymer glue solution, and obtain a prepreg after baking; the polymer glue solution is mainly composed of phenolic resin, polytetrafluoroethylene powder and an organic solvent; the polymer glue solution is prepared by mixing a polytetrafluoroethylene powder dispersion liquid and the phenolic resin; the average particle size D 50 of the polytetrafluoroethylene powder is 0.5-3 μm; the phenolic resin is prepared by a method comprising the following steps: first heat a mixture mainly composed of phenol, formaldehyde, an alkaline catalyst and water to 40-60 ℃, keep for 20-60 min, then heat to 65-85 ℃, keep for 40-120 min, and obtain the phenolic resin after dehydration treatment; (3) sequentially performing winding forming and curing on the pre-impregnated cloth to obtain the porous phenolic cloth composite.

2. The method for preparing the porous phenolic fabric composite material as described in claim 1, characterized in that, The mass of the polytetrafluoroethylene powder is 3-30% of the mass of the phenolic resin.

3. The method for preparing the porous phenolic fabric composite material as described in claim 1, characterized in that, The gel time of the phenolic resin is 150-200 s; the organic solvent is an alcohol solvent; and the mass of the organic solvent is 40-50% of the mass of the phenolic resin.

4. The method for preparing the porous phenolic fabric composite material as described in claim 3, characterized in that, The molar ratio of the phenol and formaldehyde is 1:(1-1.1); the mixture is prepared by mixing phenol, formaldehyde solution and ammonia water; and the mass ratio of the phenol and ammonia water is 100:(1-5).

5. The method of claim 1-4, wherein, The polytetrafluoroethylene powder dispersion liquid is prepared by a method comprising the following steps: putting polytetrafluoroethylene powder into an organic solvent, and then performing ultrasonic dispersion.

6. The method of claim 1-4, wherein, The foaming agent solution mainly comprises a foaming agent and a solvent; the foaming agent comprises N,N'-dinitrosopentamethylenetetramine and a foaming aid; the foaming aid is urea; the mass ratio of the N,N'-dinitrosopentamethylenetetramine and the foaming aid is (3-5):1; the solvent comprises an alcohol solvent and a ketone solvent; the mass ratio of the alcohol solvent and the ketone solvent in the foaming agent solution is 1:(8-10); and the mass fraction of the N,N'-dinitrosopentamethylenetetramine in the foaming agent solution is 1.3-2.5%.

7. The method of claim 1-4, wherein the porous phenolic cloth composite is prepared by the steps of: In step (1), the dipping speed is 1-2 m / min; in step (1), the baking temperature is 70-80℃; in step (2), the dipping speed is 1-3 m / min; in step (2), the baking temperature is 90-120℃; in step (3), the rolling pressure used in the winding forming is 0.1-0.5 MPa, and the rolling temperature is 90-120℃; and in step (3), the curing method comprises the following steps: first heating the pre-impregnated cloth after winding forming to 80-100℃, maintaining for 1-2 h, and then heating to 130-150℃, maintaining for 4-9 h.

8. A porous phenolic cloth composite prepared by the method of any one of claims 1-7.

9. A cage characterized in that, The retainer is made of the porous phenolic cloth composite of claim 8.

10. A bearing, characterized by The retainer comprises the retainer of claim 9.

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