JPH08176437A - Heat-resistant lubricating resin composition - Google Patents

Abstract

PURPOSE: To obtain a heat-resistant lubricating resin composition improved in abrasion resistance by mixing a polyphenylenesulfide resin as the principal component with a tetrafluoroethylene resin, Li2 CO3 and an aromatic polyamide fiber as the essential components. CONSTITUTION: A polyphenylenesulfide resin represented by formula I [wherein Ph is a group of formula II; Q is F, Cl, Br or H3 ; and m is 1-4] is mixed with 8-38vol.% tetrafluoroethylene, 1-20vol.% Li2 CO3 powder having a particle diameter of 0.1-400μm, and 2-20vol.% aromatic polyamide fiber having a fiber length of about 0.15-3mm and an aspect ratio of about 10-230 to form a 100vol.% mixture. If necessary, this mixture may further contain additives such as carbon, mica or MoS2 . This mixture is further mixed, and melt-kneaded and extruded through a twin-screw extruder to obtain a heat-resistant lubricating resin composition. This composition is molded and annealed at about 100-250 deg.C for about 0.5-24hr to obtain a heat-resistant sliding bearing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-resistant / lubricating resin composition used as various sliding members and a heat-resistant sliding bearing. The present invention relates to a lubricating resin composition and a heat resistant plain bearing.

[0002]

2. Description of the Related Art In recent years, as the field of application of synthetic resin slide bearings has expanded, heat resistant synthetic resin slides that exhibit good friction and wear characteristics under bearing operating conditions, especially in high temperature atmospheres, have been developed. Bearings have been strongly demanded.

Further, when an aluminum alloy or the like is used as a sliding mating material of the bearing, the bearing is required to have a property of not damaging a relatively soft sliding mating material during use. Specific examples of heat resistant plain bearings that require the above characteristics include:
There is a bearing for a heat fixing device such as a copying machine or a laser beam printer, and a general use state of such a slide bearing will be described below.

That is, a copying machine or a laser beam printer having a mechanism for transmitting information of an original image to a transfer material which is a recording material by using a charged image is generally called an electrophotographic apparatus. As illustrated in FIG. 3, a heating roller 10 that heat-fixes the toner image on the transfer material and a pressure roller 11 that presses the transfer material against the heating roller 10 to rotate the transfer material are mounted.

The former heating roller 10 is often made of an aluminum alloy, and the heater 12 is about 150-2.
It is heated to a temperature of 30 ° C. The latter pressure roller 11 is
It is made of iron material coated with silicone rubber, etc., and this is also about 70 to 150 ° C due to heat transfer from the heating roller 10.
It is heated up to.

FIG. 4 shows a heat fixing device having a mechanism different from the above heat fixing device. Instead of a metal heating roller, a heat resistant synthetic resin film is coated with a release agent. An endless ring-shaped fixing film 15 is used, and the ceramic heater 1 is provided through the fixing film 15.
6 is pressed against the pressure roller 11 to improve the heat transfer efficiency. In this case, since the pressure roller 11 is extremely close to the ceramic heater 16, the pressure roller 11 becomes even hotter than that of the fixing device using the metal heating roller 10 described above.

The ends of the rollers used in the high temperature state are supported by the synthetic resin slide bearings 13 and 14 (bearings of substantially the same shape as 14 in the apparatus of FIG. 4). Polyphenylene sulfide (hereinafter abbreviated as PPS) resin, which is a thermoplastic synthetic resin having good heat resistance and excellent mechanical strength, is used as the material.
In this case, a lubricant such as graphite, tetrafluoroethylene resin, lubricating oil, metal oxide or aromatic polyamide resin may be added to the PPS resin to enhance self-lubricating property. Many.

However, the conventional PPS resin heat-resistant / lubricating composition described above has a problem that it cannot maintain a low friction coefficient under high temperature and high load conditions and cannot sufficiently exhibit wear resistance. is there.

A resin composition has also been developed in which a heat-resistant synthetic resin powder and a tetrafluoroethylene resin are added to a PPS resin, and an aromatic polyester resin and tetrafluoroethylene are added to the PPS resin. Compositions containing a resin are disclosed in JP-A-57-167348 and JP-A-63-175065. These compositions exhibit good wear resistance at relatively low temperatures around room temperature.

[0010]

However, in a composition in which a tetrafluoroethylene resin and an aromatic polyester resin are mixed with PPS resin, the sliding partner material is an aluminum alloy (usually Mg In the case of Al alloy containing), there is a problem in that it is damaged and also wears itself.

When carbon fiber is added to such a composition, the wear resistance is improved, but when a soft aluminum alloy is used as a sliding mating material, it is damaged, and the friction causes further friction.・ Abrasion characteristics may deteriorate.

A resin composition obtained by adding a tetrafluoroethylene resin and a carbonate of an alkali metal or an alkaline earth metal to a synthetic resin is disclosed in JP-A-5-78687 and JP-A-5-112723. However, the wear resistance of these resin compositions and the damage resistance of the sliding mating material still give sufficiently satisfactory results when the soft aluminum alloy is used as the sliding mating material at high temperature as described above. It wasn't something.

Therefore, an object of the present invention is to solve the above-mentioned problems and to provide a heat-resistant / lubricating resin composition with a conventional PPS.
A low-performance friction composition that is more excellent than a resin composition, wear resistance, and non-aggressiveness against a soft alloy such as an aluminum alloy, and a high-performance composition that gives better results, or It is the heat resistant plain bearing used.

[0014]

In order to solve the above-mentioned problems, in the present invention, polyphenylene sulfide resin is used as a main component, and tetrafluoroethylene resins 8 to 38 are used.
The heat-resistant / lubricant resin composition is obtained by adding, by volume, 1 to 20% by volume of lithium carbonate and 2 to 20% by volume of aromatic polyamide fiber as essential components.

Alternatively, a heat resistant plain bearing is obtained by molding the above heat resistant / lubricating resin composition.

[0016]

The heat-resistant / lubricating resin composition of the present invention comprises a PPS resin having excellent heat resistance as a main component, and a tetrafluoroethylene resin having excellent slidability and lithium carbonate in predetermined amounts, respectively. A transition film that has the required heat resistance and good lubricity is formed on the mating material, and even a soft aluminum alloy does not scratch the surface and exhibits good lubrication properties.

[0017]

Examples PPS resins used in the present invention include synthetic resins composed of various repeating units represented by the following general formula (1).

[0018]

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Among these, a particularly typical one is represented by the following chemical formula 2, and is commercially available from Philips Petroleum Co., Ltd. under the trademark "Ryton", and its manufacturing method is described in US Pat. No. 3,354,354. No. 129 (corresponding Japanese Patent Publication No. 45-3368).

According to it, Ryton is produced by reacting p-dichlorobenzene with sodium disulfide in an N-methylpyrrolidone solvent at 160 to 250 ° C. under pressure. In this case, it is possible to freely produce resins having various degrees of polymerization ranging from those having no cross-linking to those having partial cross-linking in the resin through the post-heat treatment step. It is possible to arbitrarily select and use those having viscosity characteristics. Moreover, you may employ | adopt the linear PPS resin which does not take a crosslinked structure other than the above-mentioned Ryton PPS resin.

[0021]

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Next, as the tetrafluoroethylene resin (hereinafter abbreviated as PTFE) used in the present invention, any tetrafluoroethylene polymer can be used without particular limitation. PTFE, even if this is a molding powder,
Further, it may be fine powder for so-called solid lubricant,
Commercially available products: Mitsui DuPont Fluorochemicals Co .: Teflon 7J, TLP-10, Asahi Glass Co., Ltd .: Fluon G1
63, manufactured by Daikin Industries, Ltd .: Polyflon M15, Lubron L5 and the like. It is also possible to use PTFE modified with alkyl vinyl ether.

In the present invention, the amount of PTFE is 8 to 3
The reason why the content is limited to 8% by volume is that if it is less than 8% by volume, the lubricating properties are poor, and if it exceeds 38% by volume, the formability is remarkably impaired. From such a tendency, a more preferable compounding ratio is 10%. ~ 35% by volume.

Lithium carbonate (Li ₂ C used in the present invention
O ₃ ) is usually used in the form of powder, but various forms of O ₃ ) can be obtained by the production method, and such forms can be adopted without particular limitation.

The powdery lithium carbonate preferably has a particle diameter of 0.
It is in the range of 1 to 400 μm. This is because it is technically difficult to obtain a powder having a small diameter of less than 0.1 μm in terms of manufacturing cost, and a large diameter of more than 400 μm is not preferable because the friction and wear characteristics are not stable. From such a tendency, powdery lithium carbonate having a particle size of 0.5 to 100 μm is more preferable.

In the present invention, the amount of lithium carbonate is 1 to
The reason for limiting the content to 20% by volume is that if the amount is less than 1% by volume, the lubricating properties of the composition are poor, and if it exceeds 20% by volume, the melt viscosity becomes high and the moldability deteriorates. This is because the wear resistance deteriorates, which is not preferable.

The aromatic polyamide fiber used in the present invention may be either meta type or para type, and commercially available products include DuPont Toray Kevlar: Kevlar, Nomex, Nippon Aramid: Twaron, Teijin Company: Technora, Conex and the like.

The aromatic polyamide fiber used in the present invention has a fiber length of 0.15 to 3 mm and an aspect ratio of 10 to 10.
The number 230 is adopted and the preferable result is obtained. If the fiber length of the aromatic polyamide fiber is less than the above-mentioned predetermined range, abrasion resistance is insufficient, which is not preferable, and if the fiber length exceeds the above range, poor dispersion in the composition is not preferable. On the other hand, if the aspect ratio is less than the above range, the powder shape becomes close to that of the powder, and the effect of improving wear resistance becomes insufficient, and if the aspect ratio exceeds the above range, uniform dispersion in the composition becomes difficult, which is not preferable.

The reason why the blending ratio of the aromatic polyamide fiber used in the present invention is limited to 2 to 20% by volume is that if the content is less than 2% by volume, the abrasion resistance of the composition cannot be improved, and the lubricity of the composition is low. If it exceeds 20% by volume, the abrasion resistance of the composition deteriorates contrary to the initial purpose.

Here, the method for adding and mixing various additives to the PPS resin is not particularly limited, and is a widely used ordinary method, for example, a resin as a main component and other raw materials. Individually or after compounding, appropriately dry-mixing with a mixer such as a Henschel mixer, a ball mill, a tumbler mixer, etc., and then supplying the mixture to an injection molding machine or a melt extrusion molding machine with good melt mixing properties,
Alternatively, a method such as melt mixing in advance with a hot roll, a kneader, a Banbury mixer, a melt extruder, or the like may be used.

Further, for molding the composition of the present invention, the molding method is not particularly limited, and compression molding,
A usual method such as extrusion molding or injection molding, or after melt-mixing the composition, it is pulverized by a jet mill, a freeze pulverizer, etc., and classified into a desired particle size, or obtained without classification. It is also possible to perform fluidized dip coating using electrostatic powder, electrostatic powder coating, and the like.

The obtained powder is dispersed in a solvent,
It is also possible to carry out spray coating or dip coating.

In the present invention, various additives may be added to the lubricating composition containing PPS resin as a main component. For example, an abrasion resistance improver may be incorporated to further improve the lubricity of the composition. Specific examples of the wear resistance improver include carbon, graphite,
Examples include mica, talc, wollastonite, powders of metal oxides, whiskers such as calcium sulfate, molybdenum disulfide, aromatic polyester resins, phosphates, stearates, molten fluororesins, and ultra-high molecular weight polyethylene. You can

The heat-resistant plain bearing of the present invention molded from the above-mentioned materials is not limited in its shape, and may be a shape adapted to the shape of the heating / pressurizing roller, peripheral devices and housing. . For example, as shown in FIG. 1, the bearing may be formed not only by a single material but also by a two-color molding method to form a composite material including the bearing portion 1 and the fixing metal portion 2.

Further, as shown in FIG. 2, the heat-resistant plain bearing of the present invention comprises a bearing portion 3 and a synthetic resin such as PPS, polyamide-imide (PAI), polyimide (PI) which is excellent in heat resistance and heat insulation. Alternatively, the bearing may be a two-color molded product having a resin portion 4 in which an inorganic filler, an organic filler, or the like is added.

In order to secure the dimensional stability at the time of use at high temperature by removing the strain at the time of molding, such a bearing has a hardness of 100 to 100%.
It is desirable to perform annealing heat treatment at 250 ° C. for about 0.5 to 24 hours.

The raw materials used in Examples and Comparative Examples of the present invention are collectively shown as follows. The numbers in parentheses correspond to the numbers of the raw materials in the table below, and the mixing ratios of the components in the table are all% by volume.

(1) PPS resin (manufactured by Tososa Steel Co., Ltd .: PPS # 160) (2) PPS resin (KPS-W20 manufactured by Kureha Chemical Co., Ltd.)
5) (3) Tetrafluoroethylene resin A (Mitsui DuPont Fluorochemical Co .: Teflon 7J for molding) (4) Tetrafluoroethylene resin B (Kitamura Co .: KTL6)
10, for lubrication) (5) Lithium carbonate: Li ₂ CO ₃ (Wako Pure Chemical Industries, Ltd .: Reagent) (6) Calcium carbonate: CaCO ₃ (Wako Pure Chemical Industries, Ltd .: Reagent) (7) Potassium carbonate: K ₂ CO ₃ (manufactured by Wako Pure Chemical Industries:
Reagent) (8) Sodium carbonate: Na ₂ CO ₃ (Wako Pure Chemical Industries, Ltd .: Reagent) (9) Para-based aromatic polyamide fiber (Nippon Aramid: Twaron 1010 cut fiber fiber length 0.2)
5 mm) (10) Meta-aromatic polyamide fiber (manufactured by Teijin Ltd .: Conex cut fiber 2 de, fiber length 1 mm) (11) Carbon black (manufactured by Lion: Ketjen EC-X) (12) Graphite (manufactured by Lonza: KS-6).

[Examples 1 to 6] Raw materials were thoroughly mixed with a Henschel mixer in the proportions (volume%) shown in Table 1 and fed to a twin-screw melt extruder, and the cylinder temperature was 300 ° C and the rotation speed was 100 rpm. Extrude and granulate under melt mixing conditions,
The pellets thus obtained have a resin temperature of 310 ° C. and an injection pressure of 800.
A ring-shaped test piece having an outer diameter of 28 mm, an inner diameter of 20 mm and a width of 5 mm was molded under the injection molding conditions of kgf / cm ² and a mold temperature of 140 ° C. Using this test piece, the following high temperature radial friction and wear test was conducted.

[High Temperature Radial Friction and Wear Test] A rotating shaft made of aluminum alloy A5056 (surface roughness 3.2S) was used as a mating member, and a ring-shaped test piece was fitted around the mating member.
This was pressed against the peripheral surface of the mating material with a pressure of 3.5 kgf / cm ² , the surface temperature of the rotary shaft was controlled to 200 ° C., and a torque meter was attached to the surface of the rotary shaft to achieve a peripheral speed of 2.8.
It was continuously rotated at m / min for 50 hours. After this, the wear coefficient as the wear amount of the test piece × 10 ⁻¹⁰ cm ³ / (kgf ·
m) and the torque (kgf · cm) of the rotating shaft were measured, and the degree of damage on the surface of the aluminum alloy, which is a sliding counterpart, was observed. Regarding the evaluation of damage degree, no damage (○
The results are shown in Table 2 in a three-level evaluation of damage (mark), damage (mark) or damage (mark).

[0041]

[Table 1]

[0042]

[Table 2]

[Comparative Examples 1 to 6] Specimens were prepared in exactly the same manner as in Examples, except that the raw materials were mixed in the proportions shown in Table 1, and the high temperature radial friction and wear test described above was carried out. The torque of the rotating shaft and the degree of damage to the sliding mating material were determined and the results are shown in Table 2.

As is clear from the results shown in Table 2, Comparative Examples 1 to 6 had a large amount of wear, and Comparative Examples 4 and 6 had a large rotational torque. Further, in Comparative Examples 1 and 6, the sliding mating member was damaged.

Further, in Comparative Examples 4 to 6 in which calcium carbonate, potassium carbonate, and sodium carbonate were added as carbonates in an amount of 15% by volume, respectively, the wear amount was higher than that in Example 5 in which lithium carbonate was added at the same ratio. 2.4 times to 6.8
It is found that the wear resistance is remarkably inferior.

On the other hand, in Examples 1 to 6 satisfying all the conditions, both the wear amount and the rotating torque were low, and the aluminum alloy (A5056) as the mating material was not damaged.

The volume resistance of Example 6 was measured and found to be 1.5 × 10 ⁴ Ωcm, indicating semiconductivity.

[0048]

[Effect] As described above, the heat-resistant / lubricating resin composition of the present invention comprises a polyphenylene sulfide resin as a main component, a tetrafluoroethylene resin, lithium carbonate, and aromatic polyamide fibers in a predetermined amount. As a result, it is a high-performance composition that has low friction characteristics, wear resistance, and non-aggressiveness against soft alloys such as aluminum alloys, which are superior to conventional PPS resin compositions. It has the advantage of becoming a heat-resistant plain bearing having the same or similar physical properties.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment.

FIG. 2 is a perspective view showing another embodiment.

FIG. 3 is a cross-sectional view illustrating a usage state of a bearing in a heating / fixing device.

FIG. 4 is a cross-sectional view illustrating a usage state of a bearing in another heating / fixing device.

[Explanation of symbols]

 1, 3 Bearing part 2 Fixing metal part 4 Resin part 10 Heating roller 11 Pressure roller 12 Heater 13 and 14 Radial bearing made of synthetic resin 15 Fixing film 16 Ceramic heater

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Claims (2)

[Claims] 1. A heat resistance obtained by adding polyphenylene sulfide resin as a main component and tetrafluoroethylene resin 8 to 38% by volume, lithium carbonate 1 to 20% by volume and aromatic polyamide fiber 2 to 20% by volume as essential components. -Lubricating resin composition. 2. A heat-resistant plain bearing formed by molding the heat-resistant / lubricating resin composition according to claim 1.