阅读说明：本技术 一种轴承用聚苯并噁唑多孔含油保持架材料及其制备方法 (Polybenzoxazole porous oil-containing retainer material for bearing and preparation method thereof ) 是由 陶立明 郭丽和 王超 杨丽君 王廷梅 王齐华 于 2020-07-20 设计创作，主要内容包括：本发明提供了一种轴承用聚苯并噁唑多孔含油保持架材料及其制备方法,属于有机材料制备领域。本发明中,芳香族二元酸酐具有酸酐官能团,芳香族邻羟基二元胺中氨基的邻位含有酚羟基,该酚羟基较低温度(300℃以下)性质稳定,而在高温下(350℃及以上)能够与附近的酰亚胺环发生热重排反应脱除CO<Sub>2</Sub>分子转变为苯并噁唑片段,从而提高了轴承用聚苯并噁唑多孔含油保持架材料的强度和耐温等级,综合利用了“刚性堆垛”的物理堆砌成孔和“原位脱除CO<Sub>2</Sub>气体分子”的气相成核造孔两种机制,对多孔材料的孔性能进行调控和优化,大大降低了轴承用聚苯并噁唑多孔含油保持架材料的孔径范围及孔径分布宽度。(The invention provides a polybenzoxazole porous oil-containing retainer material for a bearing and a preparation method thereof, belonging to the field of organic material preparation. In the present invention, the aromatic dibasic acid anhydride has an acid anhydride functional group, and the aromatic o-hydroxy dibasic acid anhydride has an acid anhydride functional groupThe ortho-position of amino group in amine contains phenolic hydroxyl group, the phenolic hydroxyl group has stable property at lower temperature (below 300 ℃), and can perform thermal rearrangement reaction with nearby imide ring at high temperature (above 350 ℃) to remove CO 2 The molecules are converted into benzoxazole segments, thereby improving the strength and temperature-resistant grade of the polybenzoxazole porous oil-containing retainer material for the bearing, comprehensively utilizing the physical stacking pore-forming of rigid stacking and in-situ CO removal 2 The gas-phase nucleation pore-forming mechanism of the gas molecule regulates and optimizes the pore performance of the porous material, and greatly reduces the pore size range and the pore size distribution width of the polybenzoxazole porous oil-containing retainer material for the bearing.)

1. A preparation method of a polybenzoxazole porous oil-containing retainer material for a bearing comprises the following steps:

mixing aromatic dibasic acid anhydride, aromatic o-hydroxy diamine and a polar aprotic solvent under a protective atmosphere to perform solution polycondensation reaction to obtain an intermediate homogeneous solution;

mixing the intermediate homogeneous phase solution with a dehydrating agent, and then carrying out imidization reaction to obtain polyimide molding powder containing phenolic hydroxyl side groups;

carrying out cold isostatic pressing on the polyimide molding powder containing the phenolic hydroxyl side group to obtain a cold-pressed blank;

performing hot isostatic pressing controllable molding on the cold-pressed blank to obtain a porous polybenzoxazole material;

and carrying out oil immersion treatment on the porous polybenzoxazole material to obtain the polybenzoxazole porous oil-containing retainer material for the bearing.

2. The production method according to claim 1, wherein the aromatic ortho-hydroxy diamine is 2, 2-bis (3-amino-4-hydroxyphenyl) hexafluoropropane; the aromatic dibasic acid anhydride is pyromellitic dianhydride, 3 ', 4,4 ' -diphenyl ether tetracarboxylic dianhydride, 3 ', 4,4 ' -biphenyl tetracarboxylic dianhydride, 3 ', 4,4 ' -benzophenone tetracarboxylic dianhydride or 4,4 ' - (hexafluoro-isopropylene) diphthalic anhydride.

3. The production method according to claim 1 or 2, wherein the molar ratio of the aromatic dibasic acid anhydride to the aromatic o-hydroxy diamine is 1: 1.

4. The method of manufacturing according to claim 1, wherein the conditions for controlled hot isostatic pressing are: the pressure is 40-150 MPa, the temperature is raised from room temperature to the highest temperature at the temperature rise rate of 2-10 ℃/min, the highest temperature is 350-550 ℃, and the pressure maintaining and heat preserving time at the highest temperature is 30-300 min.

5. The method according to claim 1, wherein the imidization reaction is carried out at a temperature of 150 to 160 ℃ for 12 to 24 hours.

6. The production method according to claim 1, wherein the conditions of the cold isostatic pressing are: the pressure is 50-150 MPa, the pressure maintaining time is 15-90 min, and the temperature is room temperature.

7. The preparation method according to claim 1 or 6, wherein the cold isostatic pressing is performed in a flexible polyurethane sheath, and the Shore A hardness of the flexible polyurethane sheath is 40-60 HA.

8. The method according to claim 1, wherein the polar aprotic solvent is N-methylpyrrolidone, N-dimethylacetamide, or N, N-dimethylformamide, and the mass of the polar aprotic solvent is 3 to 6 times the total mass of the aromatic dicarboxylic anhydride and the aromatic ortho-hydroxy diamine.

9. The preparation method according to claim 1, wherein the dehydrating agent comprises one or more of benzene, toluene and xylene, and the mass of the dehydrating agent is 20 to 40% of the mass of the intermediate homogeneous solution.

10. The polybenzoxazole porous oil-containing retainer material for bearings prepared by the preparation method of any one of claims 1 to 9, which has an average pore diameter of 0.33 to 0.50 μm and a porosity of 17.7 to 20.7%.

Technical Field

The invention relates to the technical field of organic material preparation, in particular to a polybenzoxazole porous oil-containing retainer material for a bearing and a preparation method thereof.

Background

The physical and chemical properties and the lubricating property of the porous polymer bearing retainer material directly determine the precision and the service life of the bearing. With the development of long-life high-precision bearings, polymer porous oil-containing materials are also continuously developing to high temperature, high load and high performance.

The porous polyimide bearing retainer has a through hole structure, so that rolling bodies can be isolated from each other, and lubricating oil can be stored and supplied by utilizing the internal pore structure of the porous polyimide bearing retainer. When the bearing runs at a high speed, lubricating oil adsorbed in the pores is thrown out under the action of centrifugal force to participate in interface lubrication of the rolling bodies and the retainer, when the bearing stops running, the lubricating oil thrown out under the action of centrifugal force is adsorbed into the porous retainer again under the action of capillary force and is stored for being thrown out again to participate in lubrication in subsequent running, and on the premise of not needing external oil supply equipment, the repeated cyclic reciprocating motion of ' outward oil supply ' -inward oil absorption ' formed by the centrifugal action throwing out and the capillary force recovery and the alternate action of the lubricating oil is realized, so that the long-life maintenance-free oil supply of the bearing retainer is realized.

The particle size of the particles of the existing porous polyimide material is about 10-50 mu m and the particles are relatively large, the traditional preparation process (such as ZL200410010165.3 and ZL201310480892.5) of a four-column hydraulic press and limit sintering is adopted, the average pore diameter of the obtained pores is over 1.0 mu m, the capillary action of the through pores is directly determined by the average pore diameter, and the throwing-out and adsorption of the stored lubricating oil are further influenced, so that the existing porous polyimide retainer prepared by YS-20 can throw the lubricating oil out at the rotating speed of 3000rpm, and when the rotating speed of the bearing is further increased, the oil outlet speed is too high, so that the lubricating oil is thrown out from the interior of the retainer in a short time, the oil supply service life of the bearing retainer is shortened, and the porous polyimide material is not suitable for high-speed bearings.

Disclosure of Invention

In view of the above, the present invention aims to provide a polybenzoxazole porous oil-containing retainer material for bearings and a preparation method thereof. The prepared polybenzoxazole porous oil-containing retainer material for the bearing has the pore diameter range of 0.33-0.50 mu m, narrow pore diameter distribution width, higher oil content and oil content retention rate and guarantee for long-acting maintenance-free self lubrication of the high-speed bearing under severe conditions.

In order to achieve the above object, the present invention provides the following technical solutions:

the invention provides a preparation method of a polybenzoxazole porous oil-containing retainer material for a bearing, which comprises the following steps:

mixing aromatic dibasic acid anhydride, aromatic o-hydroxy diamine and a polar aprotic solvent under a protective atmosphere to perform solution polycondensation reaction to obtain an intermediate homogeneous solution;

mixing the intermediate homogeneous phase solution with a dehydrating agent, and then carrying out imidization reaction to obtain polyimide molding powder containing phenolic hydroxyl side groups;

carrying out cold isostatic pressing on the polyimide molding powder containing the phenolic hydroxyl side group to obtain a cold-pressed blank;

performing hot isostatic pressing controllable molding on the cold-pressed blank to obtain a porous polybenzoxazole material;

and carrying out oil immersion treatment on the porous polybenzoxazole material to obtain the polybenzoxazole porous oil-containing retainer material for the bearing.

Preferably, the aromatic ortho-hydroxy diamine is 2, 2-bis (3-amino-4-hydroxyphenyl) hexafluoropropane; the aromatic dibasic acid anhydride is pyromellitic dianhydride, 3 ', 4,4 ' -diphenyl ether tetracarboxylic dianhydride, 3 ', 4,4 ' -biphenyl tetracarboxylic dianhydride, 3 ', 4,4 ' -benzophenone tetracarboxylic dianhydride or 4,4 ' - (hexafluoro-isopropylene) diphthalic anhydride.

Preferably, the molar ratio of the aromatic dicarboxylic anhydride to the aromatic ortho-hydroxy diamine is 1: 1.

Preferably, the conditions for the hot isostatic pressing controlled forming are as follows: the pressure is 40-150 MPa, the temperature is raised from room temperature to the highest temperature at the temperature rise rate of 2-10 ℃/min, the highest temperature is 350-550 ℃, and the pressure maintaining and heat preserving time at the highest temperature is 30-300 min.

Preferably, the temperature of the imidization reaction is 150-160 ℃, and the time is 12-24 h.

Preferably, the conditions of the cold isostatic pressing are as follows: the pressure is 50-150 MPa, the pressure maintaining time is 15-90 min, and the temperature is room temperature.

Preferably, the cold isostatic pressing is carried out in a flexible polyurethane sheath, and the Shore hardness A of the flexible polyurethane sheath is 40-60 HA.

Preferably, the polar aprotic solvent is N-methylpyrrolidone, N-dimethylacetamide or N, N-dimethylformamide, and the mass of the polar aprotic solvent is 3-6 times of the total mass of the aromatic dicarboxylic anhydride and the aromatic ortho-hydroxy diamine.

Preferably, the dehydrating agent comprises one or more of benzene, toluene and xylene, and the mass of the dehydrating agent is 20-40% of the mass of the intermediate homogeneous solution.

The invention also provides the polybenzoxazole porous oil-containing retainer material for the bearing prepared by the preparation method in the technical scheme, wherein the average pore diameter of the polybenzoxazole porous oil-containing retainer material for the bearing is 0.33-0.50 mu m, and the porosity is 17.7-20.7 percent

The invention provides a preparation method of a polybenzoxazole porous oil-containing retainer material for a bearing, which comprises the following steps: mixing aromatic dibasic acid anhydride, aromatic o-hydroxy diamine and a polar aprotic solvent under a protective atmosphere to perform solution polycondensation reaction to obtain an intermediate homogeneous solution; mixing the intermediate homogeneous phase solution with a dehydrating agent, and then carrying out imidization reaction to obtain polyimide molding powder containing phenolic hydroxyl side groups; carrying out cold isostatic pressing on the polyimide molding powder containing the phenolic hydroxyl side group to obtain a cold-pressed blank; performing hot isostatic pressing controllable molding on the cold-pressed blank to obtain a porous polybenzoxazole material; and carrying out oil immersion treatment on the porous polybenzoxazole material to obtain the polybenzoxazole porous oil-containing retainer material for the bearing. In the invention, the phenolic hydroxyl side group and the imide ring of the polyimide molding powder containing the phenolic hydroxyl side group are subjected to thermal rearrangement reaction in the hot isostatic pressing controllable forming process to remove CO₂Gas molecules generate polybenzoxazole segments with higher rigidity and higher temperature resistance level in situ, and the removed CO is₂Gas molecules exist in a gas form in the hot isostatic pressing controllable forming process, occupy certain space and form pores, so that pore-forming caused by internal molecular structure change can be realized, and CO is used for realizing the purpose of forming pores₂The kinetic diameter of the gas is small, and therefore it is in CO₂Relatively small pore size obtained by gas nucleation, and in-situ removal of CO₂The gas phase nucleation of gas molecules realizes the regulation and control of the pore size, the distribution and the porosity ratio in the porous material. Each repeating unit of the polyimide contains two reactive phenolic hydroxyl side groups, and the phenolic hydroxyl can further perform thermal rearrangement reaction with ortho-position imide ring to remove CO₂Generating polybenzoxazole in situ after gas molecules. The invention comprehensively utilizes the physical stacking pore-forming of rigid stacking and the in-situ CO removal₂The gas-phase nucleation pore-forming mechanism of the gas molecule regulates and optimizes the pore performance of the porous material, and greatly reduces the pore size range and the pore size distribution width of the polybenzoxazole porous oil-containing retainer material for the bearing.

Furthermore, the bookIn the invention, the phenolic hydroxyl side group and the adjacent imide functional group can remove CO in the hot isostatic pressing controllable forming process₂The molecules are converted into benzoxazole (PBO) segments with higher rigidity and higher temperature resistance level, so that the strength and the temperature resistance level of the polybenzoxazole porous oil-containing retainer material for the bearing are improved.

Drawings

FIG. 1 is a Fourier transform infrared (ATR-FTIR) spectrum of a polybenzoxazole porous oil-containing cage material for bearings obtained in example 1;

FIG. 2 is a Fourier transform infrared (ATR-FTIR) spectrum of the polybenzoxazole porous oil-containing cage material for bearings obtained in examples 2 to 5;

FIG. 3 is a high-speed oil slinging curve of the polybenzoxazole porous oil-containing cage material for bearings obtained in examples 1 to 5;

FIG. 4 is an oil slinging curve of samples obtained in comparative examples 1-4;

FIG. 5 is a DMA curve (5 ℃/min, 1Hz) of the resulting polybenzoxazole porous oil-containing cage material for bearings prepared in example 1;

FIG. 6 is a DMA curve (5 deg.C/min, 1Hz) for the YS-20 material prepared in comparative example 1;

FIG. 7 is a graph comparing pore size distribution curves of samples obtained in example 1 and comparative examples 1 to 4;

FIG. 8 is a graph comparing pore size distribution curves of polybenzoxazole porous oil-containing cage materials for bearings obtained in examples 1 to 5 and a sample obtained in comparative example 1;

FIG. 9 shows the oil-impregnated friction curve of the polybenzoxazole porous oil-impregnated cage material for bearings obtained in examples 1 to 5.

The data of the embodiment show that the polybenzoxazole porous oil-containing retainer material for the bearing provided by the invention has high temperature resistance (tested by a DMA method, the storage modulus is not obviously reduced before 400 ℃, the long-term use temperature is more than 350 ℃), high strength and low friction, has higher oil content and oil content retention rate, and provides guarantee for long-acting maintenance-free self-lubrication of the high-speed bearing under severe conditions. The polybenzoxazole porous oil-containing retainer material for the bearing prepared by the invention achieves the following main performance indexes:

(1) shore hardness (D): not less than 75;

(2) coefficient of oil-containing friction: less than or equal to 0.10(MM-P2 friction abrasion tester, load 200N, linear velocity 0.432m/s, 120 minutes, dual isStainless steel rings, and the lubricating oil is PAO-10);

(3) width of grinding crack: less than or equal to 2.0 mm;

(4) ring tension: not less than 30 MPa;

(5) pore size range: 0.33-0.50 μm;

(6) porosity: more than or equal to 17 percent;

(7) oil content: not less than 15 percent.

Furthermore, cold isostatic pressing and hot isostatic pressing controllable forming are utilized, the pressing direction is three-dimensional 360-degree without dead angle, compared with a vertical two-way pressing mode in the prior art, the pressing mode is more uniform, redundant operations of using a limiting tool, a sealing sleeve and the like in the prior limiting sintering technology are overcome, the forming is convenient, the method is suitable for large-scale amplification production, and the amplification scale is only dependent on the production capacity (such as the capacity of a pressing cavity, the maximum pressure, the maximum temperature and other parameters of equipment) of cold and hot isostatic pressing forming equipment.