JPH034570B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a multilayer sliding material using polypropylene fiber as a lubricating and reinforcing base material. Specifically, a woven fabric or a non-woven fabric made of polypropylene fibers is used as a base material, and multiple layers of prepregs obtained by coating this with a thermosetting synthetic resin varnish are laminated, or one or more sheets of the prepregs are stacked together. This invention relates to a multilayer sliding material obtained by heating and pressurizing the surface of another member. Hitherto, thermosetting synthetic resin sliding materials based on cotton cloth, etc., have been widely known, and they can be impregnated with lubricating oil (Japanese Patent Publication No. 16-7051), or used as solid lubricants such as graphite or ethylene tetrafluoride. Some products are designed to improve self-lubricating properties and limit PV values by adding resin (PTFE) powder (Japanese Patent Publication No. 39-14852). In addition, we have developed a sliding member that has a low coefficient of friction in dry friction and has a sliding surface made of a cloth made of a combination of PTFE fibers and other fibers treated with resin such as phenol resin (Japanese Patent Publication No. 36-20218). Also known is a phenol resin bearing (Japanese Patent Publication No. 15954/1983), which is made of cotton chips or the like and has polyethylene powder dispersed therein, with the aim of improving lubricant retention. The present invention is particularly aimed at improving the retention of lubricating oil on sliding surfaces, and exhibits self-lubricating properties with low friction even if the lubricating oil runs out.
In that it aims at multilayer sliding materials, it can be said that it is an extension of the technical ideas of the above-mentioned Japanese Patent Publication No. 49-15954 and Japanese Patent Publication No. 36-20218. The technology related to Japanese Patent Publication No. 49-15954 uses polyethylene as a holder for lubricating oil, so if the molding temperature is slightly high, the added polyethylene will melt (the melting point of polyethylene is 135°C) and separate from the surface. There was a tendency for the molding surface to become rough. In addition, this product is not a multilayer material, but a compression molded product using cotton chips as a base material, and it also contains polyethylene powder, which tends to reduce the material strength of the resulting molded product. It was hot. In the Japanese Patent Publication No. 36-20218, since cloth made from PTFE fibers is used, in addition to the high material cost, there are also difficulties in adhesion to sliding surfaces, and In terms of the ability to retain lubricating oil on the surface, it cannot fully demonstrate its function, and furthermore, it is virtually impossible to laminate this material into multiple layers. The present invention was made to solve these problems, and has excellent lubricant retention on sliding surfaces, and even if the lubricant runs out, it exhibits self-lubricating properties with low friction. However, the technical problem is to obtain a sliding material with excellent material strength at a low cost. That is, using a woven fabric or non-woven fabric made of polypropylene fiber as a base material, multiple layers of prepregs obtained by coating this with thermosetting synthetic resin varnish are laminated, or one or more of the prepregs are coated with another layer. A multilayer sliding material is provided using polypropylene fibers as a base material, which are obtained by heating and pressurizing the polypropylene fibers by superimposing them on the surface of a member. Polypropylene has an extremely low specific gravity of 0.90 to 0.91 and is lightweight, and its primary transition point (melting point) is 168 to 170°C, which is 30°C or more higher than the melting point of polyethylene (135°C). expensive. This means that when phenolic resin, which is a common thermosetting synthetic resin, is used, the melting point of polypropylene is on the upper limit of the molding temperature (130 to 180°C) of phenolic resin, so when polyethylene is used, As such, there is little need to worry about phenomena such as melting and separation. This polypropylene fiber has the property of absorbing lubricating oil. The amount of lubricating oil absorbed is affected by temperature and time, but for example, if oil immersion treatment is carried out at a temperature of 140° C. for 30 minutes, oil impregnation of 1% by weight or more can be achieved. When polypropylene fibers containing lubricating oil are present on the sliding surface, an oil film is likely to form there when it comes into sliding contact with the mating material, and it also protects the sliding surface from lubricating oil supplied from the outside. Retains and prevents leakage. The present inventor used Mitsui Petrochemical Spunbond Co., Ltd.'s No. 24 yarn as a polypropylene fiber, with 36 yarns in the warp and 36 yarns in the weft.
Good results were obtained using a plain-woven fabric using 36 fibers (per inch) and the company's non-woven fabric called PK410B (product name). As the thermosetting synthetic resin, phenolic resin is mainly used, but epoxy resin can also be preferably used in some cases. The blending ratio of the polypropylene fiber base material and thermosetting synthetic resin is preferably in the range of 32 to 60% by weight for the former and 40 to 68% by weight for the latter. It was confirmed through experiments that the strength was maximized. Incidentally, even in the case of cotton fabric base material (specific gravity around 1.5), its mechanical strength is maximum when the blending ratio (weight ratio) with thermosetting synthetic resin is approximately 1:1, but in the case of polypropylene fiber, its specific gravity From the difference, it was found that the maximum value was found in a blending range where the amount of base material was considerably larger in volume ratio compared to cotton cloth. If the polypropylene fiber base material is less than 32% by weight,
The phenolic resin easily separates during molding, which not only significantly impairs moldability but also lowers mechanical strength. Furthermore, if the amount of the base material exceeds 60% by weight, the moldability will similarly be significantly impaired, making it impossible to obtain a satisfactory molded product. In addition to the above main constituent materials, the sliding material of the present invention includes:
For example, colorants, solid lubricants, etc. may be added in an amount of several percent by weight or less. Examples of the present invention will be described below. (Example 1) Nonwoven fabric PK410B manufactured by Mitsui Petrochemical Spunbond Co., Ltd. was used as the polypropylene fiber base material, and phenolic resin varnish ABP115N (product name) manufactured by Gunei Chemical Co., Ltd. was used as the thermosetting synthetic resin. The varnish was applied to a substrate and dried at 90° C. for 40 minutes to remove the solvent, yielding a prepreg containing 32% by weight of the substrate and 68% by weight of phenolic resin. This was wrapped around the core of a compression molding mold, loaded into the mold, held at a molding temperature of 140°C and a molding pressure of 150 kg/cm ² (pressure in the axial direction of the core) for 10 minutes, and then removed from the mold. A cylindrical laminated molded product with a diameter of 34 mm and a height of 20 mm was obtained. (Example 2) In the same manner as in Example 1, a prepreg containing 40% by weight of the base material and 60% by weight of the phenolic resin was obtained. A cylindrical laminate molded product was obtained in the same manner. (Example 3) In the same manner as in Example 1, a cylindrical laminate molded product was obtained from a prepreg containing 50% by weight of the base material and 50% by weight of the phenolic resin. (Example 4) In the same manner as in Example 1, a cylindrical laminate molded product was obtained from a prepreg containing 60% by weight of the base material and 40% by weight of the phenolic resin. Table 1 shows the radial crushing strength constants of the molded products obtained in each of the above examples.

[Table] (Example 5) A plurality of sheets of prepreg having the compounding ratio of Example 3 were stacked and sandwiched between the hot plates of a press, and then molded under the same molding conditions to produce a plate-like laminate molded product with a thickness of 7.5 mm. I got it. (Example 6) One sheet of prepreg having the compounding ratio of Example 3 was layered with multiple sheets of prepreg obtained by coating a cotton cloth base material with phenol resin varnish, and sandwiched between hot plates, and then molded under the same molding conditions. A plate-like laminate molded product with a thickness of 7.5 mm was obtained by molding. (Example 7) One sheet of prepreg having the compounding ratio of Example 3 was stacked on the primer-treated surface of a cold-rolled steel plate and sandwiched between hot plates at a molding pressure of 40 kg/cm ² and a molding temperature.
After holding it at 140℃ for 1 minute, remove it from the hot plate.
A multilayer sliding material with a steel backing was obtained. (Example 8) The prepreg obtained in Example 3 was preheated to about 120°C using a roll forming machine to have a wall thickness of 7.5 mm.
After winding and laminating the material, it was placed in a heating furnace together with the core metal and maintained at a temperature of 135±5° C. for 6 hours to proceed with curing, and then the core metal was removed to obtain a rolled tube. This was cut in the radial direction to obtain a cylindrical laminated sliding material. FIG. 1 is a graph showing the performance when the laminated sliding material having the material composition shown in Table 2 was tested under the test conditions described below. (Test conditions) 1. Test piece dimensions - laminate plate with 25 mm sides and 7.5 mm thickness. 2. Mating material - A cylindrical body with an inner diameter of 14 mm, an outer diameter of 20 mm, and a height of 20 mm, carbon steel for machine structures (S45C). 3. Sliding contact method - The cylindrical end surface of the mating material is slid into contact with the laminate surface of the test piece, and the mating material is cylindrical. Rotate around the axis. 4 Load - Cumulative load of 10Kg/ ^cm2 at 10 minute intervals, thrust load. 5 Sliding speed - 10 m/min 6 Lubrication - Immersed in mineral oil (engine oil) equivalent to SAE No. 30 at 60℃ for 1 hour, then wipe off the oil with a dry cloth, and no longer supply lubricating oil.

[Table] Comparative Examples 1, 2, and 3 had high friction coefficients from the beginning, and in all cases, the friction coefficients suddenly increased at a load of 30 kg/cm ² or less. On the other hand, the friction coefficient of Example 5 of the present invention was low and stable, around 0.1, and showed stable performance even under a load of 110 Kg/cm ² . In Comparative Examples 1, 2, and 3, almost no oil impregnation was observed in the test pieces even when immersed in oil. Therefore, after wiping off the surface of the test piece, it was shown that the test piece withstood a load of about 30 kg/cm ² due to the effect of the extremely small amount of oil adhering to it. In particular, carbon fiber woven fabrics have a smooth surface with a large amount of phenolic resin, and most of the oil can be wiped off with a dry cloth, and the carbon fiber itself has a high coefficient of friction. It depends. In the case of Example 5 of the present invention, even if the oil adhering to the surface of the test piece is wiped off, the surface layer is impregnated with oil and an oil film is formed there during frictional sliding to provide lubrication. , exhibited a low and stable coefficient of friction, clearly demonstrating the effect of using the lipophilic base material. FIG. 2 is a diagram showing the principle of the roll forming method for obtaining the rolled tube of Example 8, and is particularly suitable for obtaining a large diameter and long rolled tube. This is used as a sliding material by cutting it into an appropriate length after curing. In addition, according to roll forming, it is also possible to wind the prepreg according to the present invention in one layer or multiple layers on the inner diameter side, and to increase the reinforcing effect by winding the prepreg of a different type of base material around the outer periphery.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the performance of the sliding material of the present invention in comparison with other materials, and FIG. 2 is a diagram showing the principle of the roll forming method for obtaining rolled pipes. 1... prepreg, 2... core metal, 3... heating roll, 4... receiving roll, 5... pressure roll,
6...Guidance roll.

Claims (1)

[Claims] 1 Using a woven fabric or non-woven fabric made of polypropylene fibers as a base material, multiple layers of prepregs obtained by coating this with thermosetting synthetic resin varnish are layered, or one or more of the prepregs are coated with other layers. A multi-layer sliding material whose base material is polypropylene fibers obtained by heating and pressurizing the surfaces of parts.