JPH0359940B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a sliding member for contact with a polyester film for magnetic recording tape, which is made of a mixed resin composition of polyphenylene sulfide resin, carbon fiber, and higher fatty acid ester of glycerin. Cassette tapes for VTRs and audio equipment are mainly made of polyester film, and in order to improve sound quality and functionality, tape performance has been improved.
Improvements have been made to the case in terms of weight reduction and tape/reel performance. On the tape side, JP-A-1987-
93103, 52−73003, 52−78953, 53−78803, 53−
106783, 53−113868, 53−139511, 54−34207,
55-45118, Japanese Patent Publication No. 55-15570, etc., the surface roughness of the tape is also CLA (measured length L (reference length 2 mm) from the roughened film roughness curve in the direction of its center value). When the roughness curve is expressed as Y=f(x) with the center line of the extracted portion as the X axis and the vertical magnification direction as the Y axis,
The value given by the formula CLA=1/L∫ ^L ₀ |f(x)|dx is expressed in μ units. This measurement was performed on 8 samples, the 3 samples with the largest values were excluded, and the average value of the 5 samples was expressed. ) value has been improved to 0.02~0.03μ. On the other hand, in the case of a cassette case, since the tape rotates inside the case, high precision dimensional stability is required during plastic molding. Usually, polystyrene resin, polymethyl methacrylate resin, etc. are used for the case body, and polyacetal resin, etc. are used for the reel body. However, the guide roller pins and guide rollers (or side rollers), which are the sliding members that come into contact with the tape running surface inside the case, are made of surface-finished stainless steel, so the friction coefficient when the polyester film comes into contact with the running surface is is 0.2 to 0.3, which is a large cause of drop-out phenomenon and pronunciation problems. For this reason, the current practice is to use special grease in combination to prevent this dropout phenomenon and the generation of sliding noise. The present inventors investigated various thermoplastic resins for sliding members for contact with polyester films, and found that polyphenylene sulfide resin (hereinafter referred to as PPS)
It has been found that a resin composition containing carbon fiber and a higher fatty acid ester of glycerin as an antistatic agent as a main component is suitable for a sliding member. What is the PPS resin used here?

It is a heat-resistant resin developed by Phillips Petroleum Company in the United States, which has the molecular structure of [Formula]. Resin compositions made by mixing PPS resin with glass fiber are used as mechanical parts, and compositions made by mixing polytetrafluoroethylene resin, carbon fiber, molybdenum disulfide, graphite, etc.
It is also used as a bearing member, as seen in the specifications of USP 3882030, 4115283, and Japanese Patent Application Laid-Open No. 51-28145. However, if only carbon fiber is mixed, for example, as will be shown later in Comparative Example 1, it cannot be said that it has sufficient performance as a sliding member. The present inventors investigated ways to improve the performance of sliding members by adding various additives such as antistatic agents to resin compositions made of PPS resin and carbon fibers, and found that by adding higher fatty acid esters of glycerin, the following results were obtained: We have found that the following effects can be realized. In other words, the internal lubrication effect improves anti-friction and anti-wear characteristics. The floating of carbon fibers on the surface of the molded product is reduced. Coupled with the electrically conductive properties of carbon fibers, charging properties are reduced. The overall effect of the above three items allows the tape to run very smoothly, and as a result, we have created a guide roller pin that is an ideal sliding member that does not cause any noise or drop-out phenomenon while the tape is running. Ta. The sliding member according to the present invention includes 40 to 95 parts by weight of PPS resin, preferably 60 to 80 parts by weight, 5 to 60 parts by weight of carbon fiber, preferably 20 to 40 parts by weight, and 0.1 to 5 parts by weight of higher fatty acid ester of glycerin. , preferably 0.1
~2 parts by weight. If the amount of carbon fiber added is too large, the fibers will float on the surface of the sliding part, making it impossible to obtain favorable results in terms of friction and wear. Furthermore, if the amount of higher fatty acid ester of glycerin added is too large, a bleed phenomenon will occur on the surface of the sliding part. In addition,
The higher fatty acid ester of glycerin used in the present invention is, for example, a single ester of stearic acid, oleic acid, palmitic acid, etc., and glycerin, or a mixture thereof, and the molar ratio of the higher fatty acid to glycerin is between 1 and 3. But it's okay. The present invention will be explained in detail below with reference to Examples. Example 1 6.9 kg of PPS resin (Ryton P-4, manufactured by Phillips Petroleum Co., Ltd.) and 100 g of glycerol tristearate (manufactured by Wako Pure Chemical Industries, Ltd.) finely pulverized in a mortar were placed in a 46V type mixer and the mixture was heated at 27 kg per minute. Premix by rotating for 15 minutes, then add carbon fiber (Kurehachiop KCF-100) dried at 120°C for 3 hours.
-M107D, manufactured by Kureha Chemical Industry Co., Ltd.) (3.0 kg) was added and mixed for an additional 15 minutes. These mixed raw materials are 65mmφ
Load the dalmage type screw into the extrusion molding machine,
Cylinder temperature from 270℃ to 310℃ from hopper mouth
Extrusion molding was carried out with a gradient of 300° C. and a die temperature of 300° C., and composite pellets were obtained using a hot cut device attached to the dust part. 60g of this pellet is put into an injection molding machine at a cylinder temperature of 270 to 310.
℃, nozzle temperature 290℃, mold temperature 150℃,
Injection pressure 1000Kg/ ^cm2 , plate length 120mm, width 30mm, thickness 2mm, outer diameter 26.4mmφ, inner diameter 20.0mmφ,
A cylinder with a height of 25.0 mm and a guide pole with a length of 22.0 mm and a diameter of 2.4 mm were molded, and dropout measurements were performed on mechanical properties, friction and wear characteristics, and videotape running performance. Table of measurement results along with comparative examples
As shown in 1, the resin composition for sliding members of the present invention has excellent mechanical properties, frictional wear characteristics, and tape running properties compared to other resin compositions, and also has superior properties compared to conventional metallic guide roller pins. It is clear that this material also has excellent friction properties and tape running properties. Examples 2, 3, 4 and comparative examples 1, 2,
3 and 4 are shown, but in each example, the same equipment and method as in Example 1 were used, and the same test pieces as in Example 1 (120 mm x 30 mm x 2 mm plate, outer diameter 26.4 mmφ,
Cylinder with inner diameter 20.0mmφ, height 25.0mm and 22.0mm×
A 2.4mmφ guide pole was created and physical property tests were conducted. The results are shown in Table-1 and Table-2. Example 2 PPS (Ryton P-4) 4.9Kg Glycerol tristearate 100g Carbon fiber (Kurehachiyopu KCF-100-
M107D) 5.0Kg The number of dropouts was 0, and the friction characteristics were also excellent compared to the comparative example. Example 3 PPS (Ryton P-4) 6.7Kg Glycerol tristearate 300g Carbon fiber (Kurehachipu KCF-100-M107D)
3.0Kg The number of dropouts was 0, and the friction properties were also excellent compared to the comparative example. Example 4 PPS (Ryton P-4) 6.9Kg Glycerol trioleate 100g Carbon fiber (Kurehachipu KCF-100-M107D)
Similar good results were obtained using 3.0Kg glycerol tristearate. Comparative example 1 PPS (Ryton P-4) 7.0Kg Carbon fiber (Kurehachipu KCF-100-M107D)
3.0Kg Friction properties are on par with other resins. The dropout number is 8, which is slightly better than other resins, but the performance is considerably lower than when higher fatty acid esters of glycerin are added.

[Table] Comparative Example 2 PPS (Ryton P-4) 6.9Kg Stearic acid 100g Carbon fiber 3Kg The friction properties were the same as in Example 2, but the number of dropouts was 6, which was inferior to the Example, and the mechanical strength was The decline was also significant. Comparative Example 3 PPS (Ryton P-4) 5.5Kg Molybdenum disulfide (Nippon Molybdenum Co., Ltd. T Powder) 1.5Kg Carbon fiber 3.0Kg Friction characteristics decreased and the number of dropouts was as high as 10, so no improvement effect was recognized. . In addition, some scratches were observed on the tape running surface. Comparative Example 4 PPS (Ryton P-4) 6.9Kg Polytetrafluoroethylene powder 1.5Kg Carbon fiber 3.0Kg The friction characteristics were the same as in Example 2, but the number of dropouts was 9 and no improvement was observed. Ta.

【table】

Claims (1)

[Claims] 1 40 to 95 parts by weight of polyphenylene sulfide resin, 5 to 60 parts by weight of carbon fiber, and 0.1 to 5 parts by weight of higher fatty acid ester of glycerin selected from stearate, oleate, and palmitate of glycerin. Consisting of
Sliding member for contact with polyester film for magnetic recording tape.