JPH0561306B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a conductive sliding material composition containing polyphenylene sulfide resin as a main component. [Prior Art] In recent years, as the field of application for synthetic resin sliding bearings has expanded, there has been a strong demand for heat-resistant synthetic resin bearings that exhibit good friction and wear characteristics under bearing operating conditions, especially in high-temperature environments. In addition, with the rapid progress in mechanization of office work, it is required to have not only sliding properties but also electrical conductivity. It is well known that polyphenylene sulfide (abbreviated as PPS) resin has been used as a thermoplastic synthetic resin with good heat resistance and mechanical strength. However, this PPS resin itself has poor self-lubricating properties, so when using it as a material for parts that require lubricity, it is necessary to add a lubricant or the like to give it lubricity. Although composite materials using graphite, polytetrafluoroethylene resin, lubricating oil, metal oxides, aromatic polyamide resin, etc. have been developed, these composite materials do not perform well under high temperature and high load conditions. It cannot be said that this is sufficient to exhibit friction and wear characteristics. On the other hand, a technique has already been disclosed in which an electron-accepting compound such as a Lewis acid or a sulfuric acid halogen is applied or mixed in order to impart conductivity to the PPS resin itself.
It has not yet been put into practical use. In addition, there are products that have been given conductivity by adding conductive carbon, etc., but if you are trying to obtain good conductivity as well as good sliding properties, the volume resistivity will decrease unless the sliding properties are impaired. If the volume resistivity is too large or the volume resistivity is small, the sliding properties will be impaired or the mechanical properties will be extremely poor, making it impossible to obtain a material that has both sliding properties and conductivity at high temperatures. . [Problems to be Solved by the Invention] As described above, the conventional technology has had the problem of not being able to meet the demands of the world because there is no material that has both sliding properties and conductivity. [Means for solving the problems] In order to solve the above problems, this invention
The main component is PPS resin, 15-30% mica whose surface is coated with nickel (% is weight % based on the total amount of the composition, the same applies hereinafter), 8-18% carbon fiber, and wollastonite whose surface is coated with nickel. Or potassium titanate 5-25%, polytetrafluoroethylene resin 2-15%, molybdenum disulfide 2-7%
This method adopts the method of adding . The details will be described below. First, the PPS resin in this invention has the general formula It is commercially available from Phillips Petroleum Company of the United States under the trademark "Ryton", and its manufacturing method is disclosed in U.S. Pat. According to the report, Ryton is produced by reacting P-dichlorobenzene and sodium disulfide in N-methylpyrrolidone solvent at 160-250°C under pressure, and there are no cross-linkages in the resin. Various degrees of polymerization, ranging from those with no cross-linking to those with partial cross-linking, can be freely produced by subjecting them to a post-heat treatment process, so they have melt viscosity characteristics appropriate for the desired solvent blend. It is possible to use any selection. Next, the mica whose surface is coated with nickel in this invention is produced by applying nickel to the surface of powdered mica such as phlogopite, which is known as a solid lubricant, by electrically or chemically plating. It is coated to give it electrical conductivity. Further, the carbon fiber in this invention may be not only a normal carbon fiber but also one coated with metal such as nickel.
300, manufactured by Kureha Chemical Industry Co., Ltd.: Kureha Carbon Fiber M207S, manufactured by Toho Bethlon Co., Ltd.: HTCF/Ni, etc. can be exemplified. Further, in the wollastonite or potassium titanate whose surface is coated with nickel in this invention, a nickel layer is formed on the crystal surface of the wollastonite or potassium titanate by, for example, electrical plating or electroless (chemical) plating. The type of wollastonite or potassium titanate crystal is not particularly limited as long as it has conductivity. Here, wollastonite is also called wollastonite, and contains calcium,
It is a cyclosilicate of iron and manganese, and is a natural mineral in plate-like, columnar, fibrous, or block-like aggregates, and potassium titanate is a needle-like (whisker) mineral.
Or it is a synthetic material with plate crystals. Further, the polytetrafluoroethylene resin in this invention is a polymer of tetrafluoroethylene, and may be either a powder for molding or a fine powder for so-called solid lubricants. For example, Mitsui Manufactured by DuPont Fluorochemical Company: Teflon
7J, TLP-10, Asahi Glass: Aflon G163, Daikin Industries: Polyflon M15, LeBron L5
For example, The molybdenum disulfide used in the present invention may be in the form of a fine powder that is commonly used as a solid lubricant, such as Molycote Z manufactured by Dow Corning. The reason for limiting the amount of each of the above-mentioned nickel-coated mica, carbon fiber, nickel-coated wollastonite or potassium titanate, polytetrafluoroethylene resin, molybdenum disulfide, etc. is as follows: This is because if the amount exceeds the upper limit, it becomes difficult to achieve both sliding properties and conductivity, which is undesirable.
In other words, if the nickel-coated mica content is less than 15%, the conductivity will be poor, and depending on the combination with other additives, the wear characteristics will be poor, and if the content exceeds 30%, other additives cannot be added. This is because the wear characteristics are significantly deteriorated, so it is preferably 15 to 25%. Furthermore, if the amount of carbon fiber is less than 8%, the sliding properties will be poor, and if the amount is more than 18%, the coefficient of friction will become large. Therefore, it is preferably 8 to 13%. Furthermore, if the amount of nickel-coated wollastonite or potassium titanate crystals added is less than 5%, the conductivity will not be sufficient, and if the amount exceeds 25%, even if the conductivity is good, the wear characteristics will deteriorate. and preferably 8 to 15%. In addition, if the polytetrafluoroethylene resin is contained in a small amount (less than 2%), the sliding properties will be poor, and if the amount exceeds 15%, the amount of other additives added will be restricted, making it impossible to improve the conductivity. 12%,
If molybdenum disulfide is less than 2%, the sliding properties will be poor, and if it exceeds 7%, it will become brittle and unusable, so it is preferably 3 to 6%. Here, the method of mixing each additive with a fixed blending ratio is not particularly limited, and any commonly used method may be used, such as mixing the resin as the main component,
Other raw materials may be mixed individually or appropriately in a mixer such as a Henschel mixer, a ball mill, or a tumbler mixer, and then fed to an injection molding machine or melt extrusion molding machine with good melt-mixing properties, or , a method such as melt mixing in advance using a heated roll, kneader, Banbury mixer, melt extruder, etc. may be used. Furthermore, the method for molding the composition of the present invention is not particularly limited, and may include compression molding, extrusion molding,
A powder obtained by a conventional method such as injection molding, or by melt-mixing the composition and then pulverizing it with a jet mill, freezing pulverizer, etc., and classifying it to a desired particle size, or without classifying it. It is also possible to perform fluidized dip coating using electrostatic powder coating, electrostatic powder coating, etc. [Operation] When the surface of the molded product of the composition of the invention described above is polished to form a sliding surface, this surface contains the PPS resin, the metal nickel constituting the nickel coating,
Seven types of phases are exposed: mica coated on nickel, carbon fiber, wollastonite or potassium titanate crystals coated on nickel, polytetrafluoroethylene resin, and molybdenum disulfide. The two phases of the fiber are in close contact with each other to form an electric path and contribute to increased conductivity, while at the same time the carbon fiber and the other four phases (mica,
Wollastonite or potassium titanate, polytetrafluoroethylene resin, and molybdenum disulfide phases) greatly contribute to providing lubricity to PPS resin. [Example] The following raw materials were prepared for use in Examples and Comparative Examples. PPS resin (manufactured by Philips Petroleum Co., USA: Ryton P-4 powder), nickel-coated mica (manufactured by Repco Co., Ltd.: S-250 phlogopite with an average particle size of 22 μm) and phlogopite by an electroless method.
Carbon fiber (manufactured by Kureha Chemical Industry Co., Ltd.: Kureha Carbon Fiber M207S), Nickel-coated wollastonite (average fiber) long
25μm, average fiber diameter 3μm, made by Maruwa Biochemical Co., Ltd.: A nickel plating layer is formed on Chemorite by an electroless method so that the weight ratio of the nickel plating layer to the total amount of nickel-coated wollastonite is approximately 60%), Nickel-coated potassium titanate (average fiber length
A nickel plating layer is formed on Teismo D101 manufactured by Otsuka Chemical Co., Ltd. with an average fiber diameter of 20 to 30 μm and an average fiber diameter of 0.2 to 0.3 μm using an electroless method so that the weight ratio is approximately 65% to the nickel-coated potassium titanate whisker. Polytetrafluoroethylene resin (manufactured by Mitsui Dupont Fluorochemical Co., Ltd.: Fluorine resin lubricating powder)
TLP-10) Molybdenum disulfide (manufactured by Dow Corning:
Molykote Z) Potassium titanate whisker (manufactured by Otsuka Chemical Co., Ltd.: TEISMO D101) Ketuchen Black (manufactured by Lion Corporation: Ketuchien Black EC) Aromatic polyamide fiber (manufactured by DuPont, USA:
Kevlar 49, fiber length 1 mm) Examples 1 to 3 The above raw materials were blended in the proportions (wt%) shown in Table 1. To prepare the composition, first, the raw materials are thoroughly mixed using a Henschel mixer, then fed to a twin-screw melt extruder, and extruded and granulated under melt mixing conditions at a cylinder temperature of 300°C and a rotation speed of 100 revolutions per minute. death,
The obtained pellets were heated at a resin temperature of 310℃ and an injection pressure of 800℃.
Kg/cm ² , inner diameter 20 under injection molding conditions of mold temperature 130℃
A cylindrical test piece with an outer diameter of 26 mm and a length of 8 mm was molded. This test piece was fitted into a cylindrical shaft made of mild steel S45C with a fitting clearance of 0.5 mm, and heated to 190°C with a load of 10 kg applied in the radial direction. Rotate the shaft at a speed of 69 revolutions per minute, at the start of rotation, after 15 hours,

【table】

【table】

〔effect〕

As described above, the molded product obtained from the composition of the present invention exhibits low operating torque at high temperatures, and is imparted with electrical conductivity while maintaining excellent wear resistance. It is suitable as a material for applications where dual functions are required at the same time, such as grounding or current-carrying bearings in copying machines, carriage bearings in office automation equipment, current-carrying bearings in steering columns of automobiles, and grounding buttons in various computer equipment. It can be said that it belongs to In addition, since injection molding is possible and molding is easy, it can be said that the significance of this invention is extremely large.

Claims (1)

[Claims] 1 Mica 15-30 whose main component is polyphenylene sulfide resin and whose surface is coated with nickel.
% (% is weight % based on the total amount of the composition, the same applies hereinafter),
8-18% carbon fiber, nickel-coated wollastonite or potassium titanate 5-25
%, polytetrafluoroethylene resin 2-15%,
A conductive sliding material composition characterized in that 2 to 7% of molybdenum disulfide is added.