JPH05296234A - Thrust washer material - Google Patents

Abstract

PURPOSE:To possess an elastic body characteristic and improve the qualities of anti-wear, low friction and anti-heat by forming part or the whole of an impulse surface out of a lubricous rubber composite consisting of thermoplastic fluororesin as a first indispensable element, fluoric rubber as a second indispensable element and a fluoric polymer of a low molecular weight as a third indispensable element. CONSTITUTION:In the case of a thrust washer material assigned for axial load, part or the whole of an impulse portion is formed of a lubricous rubber composite containing thermoplastic fluororesin that is a first indispensable element and fluoric rubber that is a second indispensable element and a fluoric polymer of a low molecular weight that is a third indispensable element. The composite which has the mix of the fluoric rubber of the polymer or the copolymer of a unit monomer containing more than one fluoric atom on the average and the thermoplastic fluororesin of a polymer that possesses carbon and its kind at a main chain and the combination of fluorine at a side chain, possesses a characteristic as an elastic body. The fluoric polymer of a low molecular weight that is the third indispensable element, is combined in order to give, in addition, an excellent impulse characteristic to the elastic body such as above.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thrust washer material, and more particularly to a thrust washer material that bears an axial load.

[0002]

2. Description of the Related Art Generally, a thrust bearing is a bearing used in a portion that bears an axial load (thrust load) when a load acts in the axial direction.
There is a thrust washer. Conventionally, metal rolling bearings such as ball bearings and roller bearings have been used as thrust bearings used under high load and high speed conditions.

However, in recent years, resin bearings (thrust washers) have become mainstream for the purpose of weight reduction under low load or low speed conditions related to office machines, medical equipment, general household equipment and automobiles, and electric transmission. Materials are mainly Vespel (polyimide manufactured by DuPont), Torlon (polyamideimide manufactured by Amoco), and Victrex PEEK.
It is a non-filled product of super engineering plastic such as (PEEK manufactured by ICI) or a filled product such as a fibrous material.

Although these have substantially satisfied the demands of the market, in all of these cases, breakage and breakage such as cracks when stress is concentrated due to an accident and breakage and breakage due to impact with time have become serious problems. Therefore, there is a demand for a material having excellent low friction characteristics, wear resistance, and heat resistance as in the past, but having resistance to stress concentration and impact and having elastic body characteristics that can also serve as a cushioning material.

For example, a sheet type surface made of a diene synthetic rubber or the like with a Teflon sheet attached is used. However, similarly, since it is exposed to high pressure for a long period of time, there are problems such as deterioration of rubber and peeling of an adhesive portion, and heat resistance of Teflon which is a sliding portion is not satisfied. A type in which a diene rubber material was impregnated with oil was also studied as a means of imparting low friction characteristics and wear resistance to the elastic material, but the oil was discharged over time, and the sliding resistance gradually increased and the stick There were problems such as slipping and damage. Teflon coating on a rubber material has also been tried, but due to the problem of heat resistance of the rubber member, the wear resistance was not sufficient in the usable class.

[0006] On the other hand, a diene rubber to which a solid lubricant such as Teflon or silicon was added to provide low friction characteristics was conceived. However, addition of both results in high hardness and insufficient elasticity. However, it was not actually used because of problems such as deterioration in tensile strength and tear strength, and inferior wear resistance to conventional products. Silicon rubber and fluororubber were also targeted, but no particular superiority was recognized.

Further, in the same manner as described above, nylon-based materials and high-molecular-weight polyethylene-based materials as impact-resistant materials are added with solid lubricants such as Teflon-based and silicon-based materials to obtain low friction characteristics and wear resistance. Although the added material was devised, all of them have insufficient heat resistance and have a problem that the sliding surface is melted by heat generation. Therefore, there is a demand for a thrust washer material having low friction characteristics, wear resistance characteristics, and heat resistance while maintaining sufficient rubber elasticity.

[0008]

As described above, according to the prior art, the thrust washer material which has the characteristics of an elastic body, is excellent in low friction, abrasion resistance and heat resistance and is stable and reliable for a long period of time. There was a problem that was not solved yet.

Therefore, the main object of the present invention is to provide a stable and reliable thrust washer material which can solve the above-mentioned problems.

[0010]

The invention according to claim 1 is
A thrust washer material used for a thrust bearing that bears an axial load, wherein a part or the whole of a sliding portion is formed of a lubricating rubber composition, and the lubricating rubber composition is a thermoplastic resin which is a first essential component. It is characterized by containing a fluororesin, a second essential component fluororubber and a third essential component low molecular weight fluoropolymer.

In the present invention, the fluororubber is a polymer or copolymer of unit monomers containing an average of one or more fluorine atoms, has a glass transition point of room temperature or lower, and has rubber-like elasticity at room temperature. There is no particular limitation as long as it has the following, and a wide range can be exemplified.

Examples of the polymerization method of fluororubber include bulk polymerization, suspension polymerization, emulsion polymerization, solution polymerization, catalyst polymerization, ionizing radiation polymerization, and redox polymerization. The molecular weight of fluororubber is usually 50,000.
A polymer having a molecular weight of 0 or more is desirable, and a polymer having a molecular weight as high as possible gives good results.
Above all, it is particularly preferable to use one having a size of about 100,000 to 250,000.

Typical examples corresponding to the above conditions are tetrafluoroethylene / propylene copolymer Afras manufactured by Asahi Glass Co., Ltd., vinylidene fluoride / hexafluoropropylene copolymer DuPont / Showa Denko Viton, and fluorine. Fluorovinylidene / hexafluoropropylene / tetrafluoroethylene copolymer Technofluon made by Montefluos Co., fluorosilicone elastomer Shirastic LS made by Dow Corning, and perfluoroelastomer Daikin Perflo made by Daikin Industrial Co., Ltd. Can be mentioned.

In the present invention, the thermoplastic fluororesin which is the first essential component is a polymer having a carbon chain in the main chain and a fluorine bond in the side chain. Examples of such a thermoplastic fluororesin include tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (hereinafter abbreviated as PFA), tetrafluoroethylene.
Hexafluoropropylene / perfluoroalkyl vinyl ether copolymer (hereinafter abbreviated as EPE), tetrafluoroethene / hexafluoropropylene copolymer (hereinafter abbreviated as FEP), tetrafluoroethylene /
Ethylene copolymer (hereinafter abbreviated as ETFE), trifluorochloroethylene polymer (hereinafter abbreviated as CTFE), trifluorochloroethylene / ethylene copolymer (hereinafter abbreviated as ECTFE), polyvinyl fluoride (hereinafter PVF and (Abbreviated) and polyvinylidene fluoride (hereinafter abbreviated as PVDE) are preferably one or more polymers selected from the group consisting of: In particular,
ETFE, PFA, and FEP are preferable in consideration of not forming fibers in the kneading step, ease of kneading such as meltability, and maintenance of rubber-like elasticity of the final product. In ETFE, MI value (melt index) is 300 ° C, 21
It is preferably 1 to 20 g / 10 min at 60 g.

Any of the above resins can be produced by various polymerization methods such as catalyst emulsion polymerization, suspension polymerization, catalyst solution polymerization, gas phase polymerization and ionizing radiation irradiation polymerization. The molecular weight is preferably 50,000 or less,
Those exceeding 5,000 and almost 20,000 or less are particularly desirable.

As a typical example corresponding to the above conditions, the above-mentioned PFA PFA manufactured by Mitsui DuPont Fluorochemical Co.
Examples include MP10 and FEP, Teflon FEP100 manufactured by Mitsui DuPont Fluorochemicals, and ETFE, Aflon COP manufactured by Asahi Glass.

The composition obtained by mixing the above-mentioned fluororubber and thermoplastic fluororesin has characteristics as an elastic body. In the present invention, the low molecular weight fluoropolymer, which is the third essential component, is blended in order to impart even more excellent sliding properties to such an elastic body.

In the present invention, the low molecular weight fluoropolymer means tetrafluoroethylene (TFE), a fluoropolyether having a main structural unit —C _n F _2n —O— (n is an integer of 1 to 4), Structural unit

[0019]

[Chemical 1]

Among the polyfluoroalkyl group-containing compounds (having 2 to 20 carbon atoms) having, for example, those having a molecular weight of 50,000 or less. In order to give excellent sliding properties,
It is particularly desirable that the low molecular weight fluoropolymer has a molecular weight of 5,000 or less. Among such low molecular weight fluorinated polymers, those having an average particle size of 5 μm or less of the tetrafluoroethylene polymer represented by the following formula are particularly preferable.

[0021]

[Chemical 2]

As such a material, for example, DuPont AR made by DuPont, Furuon Lubricant L169 manufactured by Asahi Glass Co., and the like can be cited.

Next, as -C _n F _2n -O _(n is an integer from 1 to 4) average molecular weight of 50,000 or less fluoropolyethers having a main structural unit of,

[0024]

[Chemical 3]

Examples include the following: Such polymers are those having a structural unit containing a functional group such as an isocyanate group, a hydroxyl group, a carboxyl group, and an ester group in order to improve the affinity (adhesion) with other compounding materials and additives. desirable.

Specific examples of such fluoropolyethers include the following.

[0027]

[Chemical 4]

These fluoropolyethers may be used alone or in combination. Further, a fluoropolyether having activated hydrogen as a functional group and an isocyanate compound having no polyfluoropolyether group may be used in combination. Further, a fluoropolyether having an isocyanate group, diamines not containing various fluoropolyether groups, triamines, or diols not containing various fluoropolyether groups,
A method of using triols together may be adopted.

Particularly, it is desirable to use a combination of fluoropolyethers in which the functional groups react with each other to increase the molecular weight. As such, it is likewise desirable to combine, for example, those having units containing isocyanate groups with those having units containing hydroxyl groups.

Examples of the polyfluoroalkyl group-containing compound include compounds having a polyfluoroalkyl group as shown below.

[0031]

[Chemical 5]

Those having the above polyfluoroalkyl group (having 2 to 20 carbon atoms) and having an average molecular weight of 50,000 or less include:

[0033]

[Chemical 6]

And the like, a polymer of a reaction product of a compound having a reactive group and a polyfluoroalkyl group with an ethylenically unsaturated compound having a group which reacts with the reactive group (eg, fluoroalkyl acrylate), and Examples thereof include a reaction product of a compound having a reactive group and a polyfluoroalkyl group with various polymers having a group that reacts with the reactive group, or a polycondensation product of the above compound.

Like the above-mentioned fluoropolyether, the polyfluoroalkyl group-containing compound is a functional group having a high affinity for improving the affinity (adhesion) with other compounding materials and additives, such as an isocyanate group, A compound having a unit containing a hydroxyl group, a mercapto group, a carboxyl group, an epoxy group, an amino group, a sulfone group and the like is preferable.

These polyfluoroalkyl group-containing compounds may be used alone or in combination. In addition, a polyfluoroalkyl group-containing compound having a reactive group having activated hydrogen and an isocyanate compound not having a polyfluoroalkyl group may be used in combination. Also,
Adopting a method such as combining a polyfluoroalkyl group-containing compound having an isocyanate group with various polyfluoroalkyl group-free diamines, triamines or various polyfluoroalkyl group-free diol groups and triols. May be.

A combination of functional groups is preferred from the viewpoint of increasing the strength, and specifically, it has a polyfluoroalkyl group having 2 to 20 carbon atoms and is selected from a hydroxyl group, a mercapto group, a carboxyl group and an amino group. A combination with a fluoropolymer containing at least one kind, or a fluoropolymer having a polyfluoroalkyl group having 2 to 20 carbon atoms and having a unit containing an isocyanate group, and polyfluoroalkyl having 2 to 20 carbon atoms Examples thereof include a combination with a fluorine-containing polymer having a group and a unit containing a reactive group having activated hydrogen.

Among these low molecular weight fluoropolymers,
It has been found that the use of fluoroolefin polymers or fluoropolyethers gives excellent results in lubricity, and the use of tetrafluoroethylene polymers having an average particle size of 5 μm or less gives the most desirable results.

In the present invention, the mixing ratio of the fluororubber, the thermoplastic fluororesin and the low molecular weight fluoropolymer is such that the weight ratio of the fluororubber to the thermoplastic fluororesin is 5.
It is desirable that the ratio be 0:50 to 95: 5. If the blending weight ratio of the thermoplastic fluororesin exceeds 50/100,
The desired composition does not have sufficient elastic properties, and the ratio is 5/100.
This is because if it is less than this, sufficient abrasion resistance cannot be obtained.

The low molecular weight fluoropolymer is preferably 5 to 50 parts by weight with respect to 100 parts by weight of the total of the fluororubber and the thermoplastic fluororesin. This is because if the compounding ratio of the low molecular weight fluoropolymer is less than 5 parts by weight, sufficient sliding properties cannot be obtained, and if it exceeds 50 parts by weight, the rubber-like elastic properties are impaired.

In addition, with respect to the above-mentioned lubricating rubber composition, 3
Abrasion resistance can be improved by adding a cured powder of a thermosetting resin that does not melt at 00 ° C. or a heat-resistant resin powder having a glass transition point of 300 ° C. or higher.

The thermosetting resin powder is a fine powder of a phenol resin, an epoxy resin or the like after thermosetting, and the heat-resistant resin having a glass transition point of 300 ° C. or higher is a polyimide resin or an aromatic aramid resin. A powder is mentioned.

Among the commercially available resin powders, a hardened and ground product of a phenol resin is manufactured by Kanebo Ltd .: Bell Pearl H30.
0, as a cured pulverized product of polyimide resin: PWA20 manufactured by Mikasa Sangyo Co., Ltd .; as a pulverized product of aromatic aramid resin: MP-P manufactured by Asahi Kasei Co., as a thermosetting resin powder having a glass transition point Tg of 300 ° C. or higher. Manufactured by Ube Industries, Ltd .: Upilex S (Tg> 500).

The particle size of such thermosetting resin powder is 1
A resin having a particle size of ˜15 μm is preferable from the viewpoint of maintaining rubber elasticity and easiness of kneading process. The thermosetting resin powder is preferably added in an amount of 5 to 20% by weight with respect to the first to third essential components. If it is less than 5% by weight, the effect of improving wear resistance is not obtained and 2
A large amount exceeding 0% by weight is not preferable because the rubber elasticity decreases.

In addition to the above components, various additives may be added within the range not impairing the object of the present invention. For example, as a vulcanizing agent for fluororubber, isocyanurate, organic peroxide, etc., antioxidants such as sodium stearate, magnesium oxide, and calcium hydroxide, or acid acceptors, antistatic agents such as carbon, silica, alumina, etc. It goes without saying that the above-mentioned fillers, other metal oxides, colorants, flame retardants and the like may be appropriately added.

The method for mixing the various raw materials described above is not particularly limited, and the generally-used methods can be used for mixing. For example, the elastomer as the main raw material and the other raw materials may be individually mixed sequentially or simultaneously by a roll mixer or other mixer. At this time, it is desirable to provide a temperature controller to prevent heat generation due to friction.

When a roll mixer is used,
For finishing mixing, it is more preferable to tighten the roll interval to about 3 mm or less and perform thin threading.

The thrust washer material according to the present invention does not require any specially limited means in the molding process, and the primary vulcanization (140-17
After performing a pressure of 5 to 10 kgf / cm ² for 10 to 30 minutes at 0 ° C., secondary vulcanization (for example, 2 to 2 at 200 to 300 ° C.)
It may be molded into a seal by applying no pressure for 0 hours.

Further, only the lip-shaped portion or the portion of the lip-shaped portion, which is the seal portion of the thrust washer material, which is in contact with the shaft is molded with the lubricating component composition containing the above-mentioned first to third essential components, Other parts may be composite-molded with general synthetic rubber, plastic or metal.

As the general synthetic rubber at this time, vulcanized rubber such as nitrile rubber, chloroprene rubber, butadiene rubber, urethane rubber, styrene rubber, butyl rubber, acrylic rubber, silicone rubber, ethylene rubber, and fluorine rubber, or urethane, polyester. , Thermoplastic elastomers such as polyamide, vinyl chloride, polybutadiene, and soft nylon, and liquid elastomers such as liquid urethane and liquid butadiene.

[0051]

In the thrust washer material according to the present invention, a part or the whole of the sliding surface thereof is a thermoplastic fluororesin as a first essential component, a fluororubber as a second essential component and a low molecular weight as a third essential component. By forming it with a lubricating rubber composition composed of a fluorine-containing polymer, it is possible to obtain a thrust washer material that has elastic characteristics but is extremely reliable in wear resistance, low friction characteristics, and heat resistance. it can.

[0052]

EXAMPLES The raw materials used in Examples and Comparative Examples are summarized below. The mixing ratios of the respective components are all% by weight, but regarding the raw materials shown in (3) to (9), the total weight of the raw materials shown in (1) and (2) is 100.
% By weight.

(1) Vinylidene fluoride / fluoropropylene copolymer (Technoflon FOR4 manufactured by Asahi Monte Corporation)
20) (2) Tetrafluoroethylene / ethylene copolymer
(Aflon COP manufactured by Asahi Glass Co., Ltd.) (3) Low molecular weight fluoropolymer (low molecular weight TFE)
(Lubricant L169 manufactured by Asahi Glass Co., Ltd.) (4) Low molecular weight fluoropolymer (low molecular weight PFPE)
(Japan Anymont Fomblin Z-DISO
C) (5) Carbon (MT carbon manufactured by Fadelbilt) (6) Sodium stearate (general industrial material) (7) Magnesium oxide (general reagent) (8) Calcium hydroxide (general reagent) (9) Phenolic resin (Kanebo) Belpearl H300) (10) Nitrile-butadiene copolymer (NBR)
(General industrial materials hardness JIS-A70) (11) Dimethyl silicone polymer (silicon rubber)
(General industrial material hardness JIS-A70) (12) Polyimide molding (Vespel SP21 manufactured by DuPont) First, the fluororubber (1) is wound around a roll mixer having a roll interval of about 5 to 10 mm, and shown in Table 1. MT carbon, sodium stearate, Mg
O and Ca (OH) ₂ were added and kneaded. Then, the roll interval was adjusted to 1 mm, and mastication was performed about 10 times. For the purpose of preventing frictional heat at this time, cooling water was constantly passed through the roll to keep the roll temperature at 60 ° C or lower. Next, cooling water is stopped, steam is passed through the rolls, the rubber temperature is adjusted to 70 ° C or higher and 90 ° C or lower, and then the roll interval is returned to about 5 to 10 mm to obtain a low molecular weight fluoropolymer. Was added little by little and kneaded at the compounding ratio of each example shown in Table 1. After that, set the roll interval to 1 again.
It narrowed to mm and masticated 10 times.

[0054]

[Table 1]

In the compound obtained in the above steps, 150 × 150 × 1t sheet was subjected to primary vulcanization (170
It was manufactured by carrying out secondary vulcanization (230 ° C., 16 hours, free) at 10 ° C. for 10 minutes at a pressing pressure of 7 kgf / cm ² .
For each test piece, a friction test, an abrasion test, a non-stick property and an elastic body property were obtained. The method of each test is as follows.

(1) Test method-friction and wear test The obtained test piece was processed into an inner diameter of φ17 and an outer diameter of φ21, and φ
A ring test piece was obtained by adhering it to a 17 × φ21 × 10 SPCC ring piece. Mating material is SUJ2 (bearing steel) φ6 × φ
A 33 × 6 disc-shaped test piece was prepared and evaluated using a thrust type friction wear tester. The condition is a sliding speed of 128 m / min,
The surface pressure was 3.5 kgf / cm ² . Table 2 shows the friction coefficient and wear coefficient after 500 hours.

(2) Non-adhesion In the obtained test piece, the contact angle to water was measured by a goniometer-type contact angle measuring device, and the larger the contact angle, the better the non-adhesiveness. The results are shown in Table 2.

(3) Elastic body property The obtained test piece is compliant with JIS-K6301,
The tensile strength, elongation, and hardness (JIS-A) were investigated. The results are shown in Table 2.

(4) Impact resistance characteristics The test pieces obtained were tested according to ASTM D256,
The Izod impact strength was investigated. The results are shown in Table 2.

[0060]

[Table 2]

Comparative Example In the comparative example, the raw materials were mixed in the proportions shown in Table 1, and kneading, molding and vulcanization were performed in the same manner as in the examples. In addition, the test pieces were adjusted and tested in exactly the same manner as in the examples. The results are shown in Table 2.

Claims (7)

[Claims] 1. A thrust washer material used in a thrust bearing that bears an axial load, wherein a part or the whole of a sliding portion is formed of a lubricating rubber composition, and the lubricating rubber composition comprises: A thermoplastic fluororesin which is one essential component, a fluororubber which is a second essential component, and a low molecular weight fluoropolymer which is a third essential component,
Thrust washer material. 2. The thrust washer material according to claim 1, wherein a cured powder of a thermosetting resin or a heat resistant resin powder having a glass transition point of 300 ° C. or higher is added to the lubricating rubber composition. 3. The thermoplastic fluororesin as the first essential component is a tetrafluoroethylene / ethylene copolymer,
The thrust washer material according to claim 1, which is one or more selected from the group consisting of a tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer and a tetrafluoroethylene / hexafluoropropylene copolymer. 4. The second essential component has a molecular weight of 100,0.
A fluororubber of from 00 to 250,000.
Thrust washer material. 5. The fluororubber which is the second essential component,
Group consisting of tetrafluoroethylene / propylene copolymer, vinylidene fluoride / hexafluoropropylene copolymer, vinylidene fluoride / hexafluoropropylene / tetrafluoroethylene copolymer, fluorosilicone copolymer and perfluoro-based copolymer The thrust washer material according to claim 1, which is one or more polymers selected from the group consisting of: 6. The low molecular weight fluoropolymer as the third essential component is selected from the group consisting of tetrafluoroethylene polymers having an average molecular weight of 50,000 or less, fluoropolyethers and polyfluoroalkyl group-containing compounds.
The thrust washer material of claim 1, which is one or more polymers. 7. The thrust washer material according to claim 1, wherein the low molecular weight fluoropolymer which is the third essential component is a tetrafluoroethylene polymer having an average particle size of 5 μm or less.