JPS6243459A - Electrically conductive sliding material composition - Google Patents

Abstract

PURPOSE:An electrically conductive sliding material composition, obtained by adding an Ni-coated solid lubricant, carbon fibers, Ni-coated wollastonite, polytetrafluoroethylene resin and molybdenum disulfide to polyphenylene sulfide resin and having improved sliding characteristics and electric conductivity at the same time. CONSTITUTION:An electrically conductive sliding material composition obtained by adding (A) 15-30wt%, based on the total composition, solid lubricant, e.g. mica or graphite, having the surface coated with Ni by the electric or chemical plating, (B) 8-18wt%, based on the total composition, carbon fibers, (C) 5-25wt% based on the total composition, crystals of wollastonite or potassium titanate having the surface coated with Ni, (D) 2-15wt%, based on the total composition, powdery or fine powdery polytetrafluoroethylene resin and (E) 2-7wt% fine powdery molybdenum disulfide to polyphenylene sulfide resin. Preferred amounts of the components are as follows, 15-25wt% component (A), 8-13wt% component (B), 8-15wt% component (C), 5-12wt% component (D) and 3-6wt% component (E).

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to a conductive sliding material composition containing polyphenylene sulfide resin as a main component.

[Conventional technology]

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 usage conditions, especially in high-temperature environments. 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 provide lubricity, for example. Although composite materials using graphite, polytetrafluoroethylene resin, lubricating oil, metal oxides, aromatic polyamide resin, etc. have been developed, these composite materials also have very poor performance 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 of applying or mixing an electron-accepting compound such as a Lewis acid or a halogen sulfate in order to impart conductivity to the PPS resin itself has already been disclosed, but it has not yet been put to 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 increase unless the sliding properties are impaired. On the other hand, if the volume resistivity is low, the sliding properties will be impaired or the mechanical properties will be extremely poor, so that a material that has both sliding properties and electrical conductivity at high temperatures has not been obtained.

[Problem that the invention seeks to solve]

As described above, the conventional technology has had the problem of not being able to meet the needs of the public because there is no material that has both sliding properties and electrical conductivity.

[Means for solving problems]

In order to solve the above-mentioned problems, this invention is a solid lubricant whose main component is PPS resin and whose surface is coated with nickel. 8-18% fiber, 5-25% wollastonite or potassium titanate crystals coated on the L side with nickel, 2-15% polytetrafluoroethylene resin
%, and 2 to 7% of molybdenum disulfide is added. The details will be described below.

First, the PPS resin in this invention is a synthetic resin represented by the general formula %. Here, -ph- in the formula is 9
m, and Q is a halogen of F, CI, Br or C)I
3, m represents an integer of 1 to 4. Among these, a particularly typical one is commercially available from Phillips Petroleum Company of the United States under the trademark "Rydon," and its manufacturing method is described in U.S. Pat. No. 3,354,129 (corresponding patent It is disclosed in Japanese Patent Publication No. 45-3368). According to it, Lydon is 160-2 in N-methylpyrrolidone solvent.
It is produced by reacting P-dichlorobenzene and sodium disulfide under pressure at 50°C, and the resin has various degrees of polymerization, ranging from no cross-linking to partial cross-linking. Since the solvent can be freely manufactured by subjecting it to a post-heat treatment process, it is possible to arbitrarily select and use a solvent having appropriate melt viscosity characteristics for the desired solvent blend.

Next, the solid lubricant C whose surface is coated with nickel in this invention (hereinafter referred to as nickel-coated lubricant) is:
For example, if the surface of mica, graphite, aromatic polyamide fiber, or other solid lubricant is coated with nickel by electrical or chemical plating, and it is made conductive, the type of solid lubricant is determined. It is not particularly limited.

Further, the carbon fiber in the present invention may be not only a normal carbon fiber but also one coated with a metal such as nickel. Examples include carbon fiber M2O2S, manufactured by Toho Heslon Co., Ltd.: HTCF/Ni.

Further, in the wollastonite or potassium titanate crystal whose surface is coated with nickel in this invention, a nickel layer is provided on the surface of the wollastonite or potassium titanate crystal by, for example, electroplating 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 with plate-like, columnar, fibrous, or block-like aggregates, and potassium titanate is a synthetic substance with whisker or plate-like crystals.

The polytetrafluoroethylene resin in this invention is a polymer of tetrafluoroethylene, and may be a powder for molding, a so-called solid, or a fine powder for use as a lubricant, for example. Mitsui DuPont Fluorochemical Co., Ltd.: Teflon 7JTLP-10, Asahi Glass Co., Ltd. Nearflon G163, Daikin Industries, Ltd.: Polyflon M15
, LeBlon Shi5, etc. can be exemplified.

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 Molycoor L and Z manufactured by Dow Corning.

The reason why the amounts of each of the above nickel-coated lubricants, carbon fibers, nickel-coated wollastonite or potassium titanate crystals, polytetrafluoroethylene resin, molybdenum disulfide, etc. are limited as above is that they are less than the respective lower limits. This is because a small amount or a large amount exceeding the upper limit is undesirable because it becomes difficult to achieve both sliding properties and conductivity. That is, the nickel-coated solid lubricant is 15
If the amount is less than 30%, the conductivity will be poor, and depending on the combination with other additives, the wear characteristics will be poor, and if the amount exceeds 30%, it will become impossible to add other additives, and the wear characteristics will deteriorate significantly. , 15 to 25% is preferable in practice. Furthermore, if the amount of carbon fiber is less than 8%, the sliding properties will deteriorate, and if the amount is more than 18%, the coefficient of friction will become large. In addition, when the amount of nickel-coated wollastonite or potassium titanate crystal added is less than 5%, conductivity is insufficient and 2
If the amount exceeds 5%, the wear characteristics will deteriorate even if the conductivity is good, so it is preferably 8 to 15%.
It is. 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. 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 3 to 6% is practically preferable.

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 main component resin and other raw materials individually, or using a Henschel mixer. , ball mill,
After dry mixing as appropriate using a mixer such as a tumbler mixer, the mixture is supplied to an injection molding machine or melt extrusion molding machine with good melt mixing properties, or it is melted in advance using a heated roll, kneader, Banbury mixer 1 melt extruder, etc. A method such as mixing may be used. In addition, the method for molding the composition of the present invention is not particularly limited, and conventional methods such as compression molding, extrusion molding, injection molding, etc.
Or after melt-mixing the composition, use a jet mill,
The powder is pulverized by a freezing pulverizer or the like and classified to a desired particle size, or it is also possible to perform fluidized dip coating, electrostatic powder coating, etc. using the obtained powder without classifying it.

[Operation] When the surface of the molded product of the composition of the present invention described above is polished to form a sliding surface, this surface is coated with PPS resin, metal nickel constituting the nickel coating, and solid lubricant coated with nickel. Seven types of phases are exposed: metallic nickel, carbon fiber, wollastonite or potassium titanate crystals coated with nickel, polytetrafluoroethylene resin, and molybdenum disulfide, and two of these phases, metallic nickel and carbon fiber, are exposed. At the same time, these carbon fibers and the other four phases (solid lubricant, wollastonite or potassium titanate, polytetrafluoroethylene resin) , and molybdenum disulfide phases) are PP
It greatly contributes to imparting lubricity to the S resin.

〔Example〕

Raw materials were prepared for use in Examples and Comparative Examples.

■PPSm fat (Philips Vetroli, USA 7 ml,
[: Ryton p-4 powder), ■Nickel-coated mica (
A nickel plating layer is provided on S-250 phlogopite with an average particle size of 22 μm by an electroless method so that the weight ratio of nickel to the weight of the nickel-coated mica is approximately 40%), Carbon fiber (manufactured by Kureha Chemical Industry Co., Ltd.: Kureha Carbon Fiber M2O7S), ■Nickel-coated wollastonite (average fiber length 25 μm)
1 Average fiber diameter of 3 μm, manufactured by Maruji Biochemical Co., Ltd.: The weight ratio of the nickel plating layer to the total amount of nickel-coated wollastonite is approximately 60% using the electroless method on Chemolite.
Nickel-coated potassium titanate (average fiber length 20-3
0 μm, average fiber diameter 0.2 to 0.3 μm manufactured by Daikyu Kagaku Co., Ltd.: Teismo D101 by electroless method, the weight ratio is about 65 to the nickel-coated potassium titanate whisker.
%), ■Polytetrafluoroethylene resin (manufactured by Mitsui DuPont Fluorochemical Co., Ltd.; fluororesin lubricating powder TLP-10) ■Molybdenum disulfide (manufactured by Dow Corning Company: Molybdenum)
Coat Z) ■Potassium titanate whisker (manufactured by Daikyu Kagaku Co., Ltd.: Teismo 0101) ■Ketjen Black (manufactured by Lion Corporation: Ketjen Black EC) [Phase] 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 in a Henschel mixer, then fed to a twin-screw melt extruder, and extruded and granulated at a cylinder temperature of 300°C and a rotation speed of 100 revolutions per minute. The resulting pellets were injection molded at a resin temperature of 310°C, an injection pressure of 800 kg/cm, and a mold temperature of 130°C to an inner diameter of 20 mm and an outer diameter of 25 mm.
A cylindrical test piece with a length of B mm and a length of B mm was molded. This test piece was made of mild steel 545C with a fitting clearance of 9.
Fit it into a cylindrical shaft with a diameter of 5 mm, and 1 in the radial direction.
It was heated to 190°C with a load of 0 kg applied. Rotate the shaft at a speed of 69 revolutions per minute, at the start of rotation, after 15 hours,
Table 1 Table 2 The respective rotational torques were measured after 44 hours.

In addition, the weight loss after 44 hours was also measured, and this was taken as the amount of wear. The presence or absence of sound during operation was also investigated, and the electrical resistance was measured by sandwiching the end surfaces of the cylindrical test piece between electrodes, and the results are summarized in Table 2.

As is clear from Table 2, Comparative Examples 1 to 3 are Examples 1 to 3.
Unlike 3, even if the electrical resistance is small, the rotational torque is unstable and the amount of wear is large (as in Comparative Examples 2 and 3).
Even if the torque and wear results were good (as in Comparative Example 1), a composition with high electrical resistance, low electrical resistance, stable low rotational torque, and low wear amount could not be obtained. .

〔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.

Patent applicant: Western Bear Rulon Industrial Co., Ltd. Agent: Kama 1) Text 2

Claims (1)

[Claims] A solid lubricant whose main component is polyphenylene sulfide resin and whose surface is coated with nickel (15-30%).
(% by weight based on the total composition, the same applies hereinafter), carbon fiber 8
~18%, nickel-coated wollastonite or potassium titanate crystals 5-25%, polytetrafluoroethylene resin 2-15%, and molybdenum disulfide 2-7%. Sliding material composition.