JPS6140260B2 - - Google Patents

Description

Detailed Description of the Invention 3-1 Technical Field The present invention relates to a thermoplastic polyurethane resin composition with excellent sliding properties. 3-2 Background Conventionally, thermoplastic polyurethane has rubber elasticity and is thermoplastic, so it is inexpensive and
Because injection and extrusion molding is suitable for parts with complex shapes, it has been put into practical use in a wide range of fields such as automobile parts, precision industrial parts, and home appliance parts. However, when used as a sliding mechanical component such as a bearing or a slider, its wear resistance is not sufficient and the sliding interface needs to be lubricated or greased. In this case, in order to prevent oil from running out at the sliding interface, a separate lubricating oil replenishment mechanism must be provided, resulting in problems of complicated parts and high costs. To improve the wear resistance of thermoplastic polyurethane itself, there is a method of adding and mixing solid lubricants such as tetrafluoride resin powder, molybdenum disulfide, or graphite, but the effects of these solid lubricants are not sufficient; Under harsh sliding conditions, it was still necessary to lubricate. 3-3 Structure of the Invention The present inventors have succeeded in improving the drawbacks of such thermoplastic polyurethane resins and found a thermoplastic polyurethane resin composition that has excellent sliding properties such as wear resistance and low coefficient of friction. It is. That is, as described in claim 1, an oil holding carrier having a specific surface area of 1 m ² /g or more and a lubricating oil are mixed in a volume ratio of 1/10 to 1/1 (carrier/oil), The lubricating oil is added to the thermoplastic polyurethane resin and mixed so that the volume ratio of the lubricating oil is 3 to 15% based on the total composition. The thermoplastic polyurethane resin used here is
It is a rubber-like elastic polymer whose molecule has a partially crosslinked urethane group, and is commercially available, for example, under the trade name Elastran (manufactured by Nippon Elastran Co., Ltd.). Activated carbon having a specific surface area of 1 m ² /g or more is used as the oil-holding carrier, and its purpose is to prevent oil separation during processing and bleeding of lubricating oil inside the molded product. The lubricating oil must not corrode or swell the base resin, and must have a low volatile content during injection/extrusion molding. Desirable lubricating oils include, but are not limited to, hydrocarbon oils. The amount of lubricating oil added should be between 3 and 15% by volume. If it is less than 3% by volume, a sufficient lubricating effect cannot be obtained, and if it exceeds 15% by volume, molding failures due to oil separation are likely to occur and the physical properties of the polyurethane itself are impaired. The amount of oil holding carrier added depends on the volume ratio with the lubricating oil.
Must be 0.1-1 (carrier/oil). If the ratio is less than 0.1, the oil retention effect will not be sufficient and molding problems will occur due to oil separation. If the ratio exceeds 1, the lubricating oil will be completely adsorbed on the carrier and will be prevented from leaching to the sliding interface, making it impossible to obtain a sufficient lubricating effect. The thermoplastic polyurethane resin composition as described in claim 1 thus obtained has excellent sliding properties and can be put to practical use as sliding parts. However, when processing by injection molding, the time required for biting into the screw becomes long, which tends to increase the time required for molding. The inventors of the present invention further investigated how to shorten the time required for biting into the screw in injection molding, and found that
The composition described in claim 2 has been discovered. That is, for the composition described in claim 1, 5 parts by weight of a polyamide resin with a melting point of 200°C or less is added to 100 parts by weight of thermoplastic polyurethane as a base material resin.
~40 parts by weight are added and mixed. Thermoplastic polyurethane and general resins, e.g.
It has been known in the past that PVC resin, ABS resin, acetal resin, acrylic resin, etc. can be mixed freely, but by mixing it with polyamide resin by the present inventors, the time required to feed the screw into the screw can be greatly increased. It was discovered for the first time that it could be shortened. As the polyamide resin used in the present invention, 200
Any polyamide having a melting point of 0.degree. C. or less may be used, such as nylon 11 or nylon 12.
In order to maintain the rubber-like elasticity of polyurethane,
The lower the elastic modulus of polyamide, the better, and elastomer type polyamide is most desirable. 3-4 Examples Examples of the present invention are shown below. (Example 1) Decomposition temperature for thermoplastic polyurethane resin
Mineral paraffin oil at 350°C was mixed at 10 vol% and activated carbon having a specific surface area of 1000 m ² /g was mixed at 5 vol%, and the mixture was melt-kneaded using a screw extrusion kneader to form pellets. This product was molded into a predetermined shape using an injection molding machine with a screw diameter of 32 mm. (Example 2) For 100 parts by weight of thermoplastic polyurethane resin,
20 parts by weight of a polyamide elastomer with a melting point of 160°C, and 10 Vol% of the mineral paraffin oil described in Example 1 and 5 Vol% of activated carbon based on the entire composition.
Add and mix so that the screw diameter of this
It was molded into the specified shape using a 32 mm injection molding machine. 3-5 Effects Table 1 shows the friction characteristics, rebound modulus, and plasticization time in injection molding of Examples 1 and 2 of the present invention. For comparison, Table 1 also shows the physical properties of a thermoplastic polyurethane resin containing no additives and a thermoplastic polyurethane resin to which 5% by weight of tetrafluoride resin wax was added. As is clear from Table 1, the examples of the present invention have significantly improved wear resistance and a reduced coefficient of friction. Furthermore, the plasticization time of the composition of Example 2 during injection molding is equal to or less than that of an additive-free thermoplastic polyurethane resin, and the time required for molding can be shortened. 【table】

Claims (1)

[Claims] 1. Thermoplastic polyurethane resin has a specific surface area of 1 m ² /
g or more of activated carbon and lubricating oil, the volume ratio of activated carbon to lubricating oil is 1:10 to 1:1, and the volume ratio of lubricating oil to the total composition is 3 to 15%. A thermoplastic polyurethane resin composition. 2 A resin composition in which 100 parts by weight of thermoplastic polyurethane resin is mixed with 5 to 40 parts by weight of polyamide resin having a melting point of 200°C or less, contains activated carbon with a specific surface area of 1 m ² /g or more and lubricating oil, and the activated carbon and lubricating oil are mixed together. A thermoplastic polyurethane resin composition characterized in that the volume ratio is 1:10 to 1:1, and the volume ratio of lubricating oil to the total composition is 3 to 15%.