JP3204537B2 - Sliding member for plastic - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sliding member having excellent sliding properties. In particular, the present invention relates to a sliding member used when a mating material is a plastic member made of a film or other molded product under severe conditions in a high-temperature atmosphere.

[0002]

2. Description of the Related Art In recent years, many plastic products have been used as mechanical parts in order to reduce the weight of the machine and reduce the product cost, and the plastic products are often used for parts requiring slidability. . Conventionally, as a resin composition with good slidability, a resin such as polyamide, polyacetal, polyphenylene sulfide, polytetrafluoroethylene, etc. to which additives for improving the sliding properties such as solid lubricants and lubricating oils are added. Has been used. These can be used in a relatively low-temperature atmosphere without any particular problem. However, as they become hotter, they are more susceptible to wear, and frictional heat is added to cause seizure or melting, making them unusable.

[0003] For this purpose, it has been proposed to add a fibrous material such as glass fiber, carbon fiber and various whiskers for the purpose of improving abrasion resistance and heat resistance. Since the mating material is easily damaged during sliding, there is a problem that the mating material is easily worn at the same time as the mating material is worn. In particular, recently, a plastic member called super engineering plastic (super engineering plastic) having excellent heat resistance, strength and dimensional stability has been used instead of a metal member as a mating material of a sliding member. These are relatively soft as compared with conventional sliding members such as ceramics and metals. In the case of various plastic molded products such as plastic films made of such super engineering plastics, the above tendency is strongly exhibited.

For example, the glassy carbon proposed in Japanese Patent Application Laid-Open Nos. 4-4295 and 4-4296 is too hard, and when the super engineering plastic is a mating material, it wears the super engineering plastic. Therefore, it is not preferable. In the above publication, only a hard metal such as steel or stainless steel is disclosed as a counterpart material. Conversely, when a plastic material is used as a mating material for a resin composition filled with a filler having a low hardness, the resin composition is severely worn and cannot be used as a sliding member. As described above, when a relatively soft material is selected as the mating material, the selection of the filler must be performed carefully.

[0005] On the other hand, as is often seen in OA equipment and the like, the temperature inside the machine may increase significantly due to the high density of parts due to the compactness of the machine or the improvement of the processing capability of the machine. At a high temperature, a sliding material mainly composed of a so-called general purpose engineering plastic such as polyamide and polyacetal had insufficient heat resistance and was deformed and could not be used. Also, plastics with a large coefficient of linear expansion, even if deformation at high temperatures can be suppressed, change in dimensions due to expansion,
In some cases, the precision required for precision parts cannot be satisfied. In other words, the characteristics required for sliding parts used at high temperatures are different from those of conventional sliding parts, because they are physical properties such as heat resistance and dimensional stability rather than friction coefficient. Materials must be selected from completely different perspectives.

[0006]

The object of the present invention is to solve the above is to solve the problems that exist in the prior art and to provide particularly wear-resistant, the plastic sliding element which is excellent in heat resistance, etc. .

[0007]

Means for Solving the Problems] sliding member of the present invention that the plastic member to the mating member is a thermotropic liquid crystal polymer 100 is a polymer or copolymer comprising monomer units represented by the following general formula of 3 Of inorganic powder having a Mohs' hardness of 2 to 4 to 20 to 130 parts by weight.

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The details of the present invention will be described below. Thermotropic liquid crystal polymer is a polymer or copolymer comprising monomer units represented by the general formula of 3 in the present invention, first, shows optical anisotropy in molten, and a polymer having a thermoplastic. A polymer that exhibits optical anisotropy when melted exhibits the property that the polymer molecular chains take a regular parallel arrangement in the melted state. The properties of the optically anisotropic molten phase can be confirmed by a usual polarization inspection method using a crossed polarizer. Examples of the liquid crystal polymer include liquid crystalline polyester, liquid crystalline polycarbonate, liquid crystalline polyesterimide and the like, and specific examples thereof include (whole) aromatic polyester, polyesteramide, polyamideimide, polyestercarbonate and polyazomethine.
Thermotropic liquid crystal polymers generally have an elongated and flat molecular structure, and have high rigidity along the long chain of the molecule.
It has a plurality of chain extension bonds in either coaxial or parallel relationship. In the thermotropic liquid crystal polymer used in the present invention, a part of one polymer chain is composed of a polymer segment forming an anisotropic molten phase, and the remaining portion is a polymer segment not forming an anisotropic molten phase. Also included are polymers composed of Further, a composite of a plurality of thermotropic liquid crystal polymers is also included.

Representative examples of the monomers constituting the thermotropic liquid crystal polymer include (A) at least one kind of aromatic dicarboxylic acid, (B) at least one kind of aromatic hydroxycarboxylic acid type compound, and (C) aromatic diol type compound. (D) (D1) aromatic dithiol, (D2) aromatic thiophenol, (D3) at least one aromatic thiol carboxylic acid compound, (E) aromatic hydroxyamine, aromatic diamine Aromatic compounds such as at least one of the compounds are exemplified. These may be used alone, but most are (A) and (C);
(A) and (D); (A), (B) and (C); (A),
(B) and (E); or a combination such as (A), (B) and (C) and (E).

The aromatic dicarboxylic acid compound (A) includes terephthalic acid, 4,4'-diphenyldicarboxylic acid, 4,4'-triphenyldicarboxylic acid, 2,6-naphthalenedicarboxylic acid, and 1,4- Naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, diphenylether-4,4'-dicarboxylic acid, diphenoxyethane-
4,4'-dicarboxylic acid, diphenoxybutane-4,4'-
Dicarboxylic acid, diphenylethane-4,4′-dicarboxylic acid, isophthalic acid, diphenylether-3,3′-dicarboxylic acid, diphenoxyethane-3,3′-dicarboxylic acid, diphenylethane-3,3′-dicarboxylic acid, 1,6
-Aromatic dicarboxylic acids such as naphthalenedicarboxylic acid,
Or chloroterephthalic acid, dichloroterephthalic acid,
Alkyl, alkoxy or halogen substituents of the above aromatic dicarboxylic acids represented by bromoterephthalic acid, methylterephthalic acid, dimethylterephthalic acid, ethylterephthalic acid, methoxyterephthalic acid, ethoxyterephthalic acid and the like.

(B) The aromatic hydroxycarboxylic acid compounds include aromatic hydroxycarboxylic acids such as 4-hydroxybenzoic acid, 3-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid and 6-hydroxy-1-naphthoic acid. Carboxylic acid, or 3-methyl-4-hydroxybenzoic acid, 3,
5-dimethyl-4-hydroxybenzoic acid, 2,6-dimethyl-4-hydroxybenzoic acid, 3-methoxy-4-
Hydroxybenzoic acid, 3,5-dimethoxy-4-hydroxybenzoic acid, 6-hydroxy-5-methyl-2-naphthoic acid, 6-hydroxy-5-methoxy-2-naphthoic acid, 2-chloro-4-hydroxybenzoic acid Acid, 3-chloro-4-hydroxybenzoic acid, 2,3-dichloro-4-hydroxybenzoic acid, 3,5-dichloro-4-hydroxybenzoic acid, 2,5-dichloro-4-hydroxybenzoic acid, 3- Bromo-4-hydroxybenzoic acid, 6-hydroxy-5-chloro-2-naphthoic acid, 6-hydroxy-
7-chloro-2-naphthoic acid, 6-hydroxy-5,7
And alkyl-, alkoxy-, or halogen-substituted aromatic hydroxycarboxylic acids such as -dichloro-2-naphthoic acid.

(C) As the aromatic diol, 4,4'-
Dihydroxydiphenyl, 3,3′-dihydroxydiphenyl, 4,4′-dihydroxytriphenyl, hydroquinone, resorcinol, 2,6-naphthalenediol,
4,4'-dihydroxydiphenyl ether, bis (4-
(Hydroxyphenoxy) ethane, 3,3′-dihydroxydiphenyl ether, 1,6-naphthalenediol,
2,2-bis (4-hydroxyphenyl) propane, bis
Aromatic diols such as (4-hydroxyphenyl) methane,
Or chlorohydroquinone, methylhydroquinone,
Alkyl, alkoxy or halogen-substituted aromatic diols such as tert-butylhydroquinone, phenylhydroquinone, methoxyhydroquinone, phenoxyhydroquinone, 4-chlororesorcin and 4-methylresorcin are exemplified.

(D1) Examples of the aromatic dithiol include benzene-1,4-dithiol, benzene-1,3-dithiol, 2,6-naphthalene-dithiol, and 2,7-naphthalene-dithiol. (D2) Examples of the aromatic thiophenol include 4-mercaptophenol, 3-mercaptophenol, and 6-mercaptophenol. (D3) Examples of the aromatic thiol carboxylic acid include 4-mercaptobenzoic acid, 3-mercaptobenzoic acid, 6-mercapto-2-naphthoic acid, and 7-mercapto-2-naphthoic acid.

(E) As aromatic hydroxyamine and aromatic diamine compounds, 4-aminophenol, N-
Methyl-4-aminophenol, 1,4-phenylenediamine, N-methyl-1,4-phenylenediamine, N,
N'-dimethyl-1,4-phenylenediamine, 3-aminophenol, 3-methyl-4-aminophenol, 2
-Chloro-4-aminophenol, 4-amino-1-naphthol, 4-amino-4'-hydroxydiphenyl,
4-amino-4'-hydroxydiphenyl ether, 4
-Amino-4'-hydroxydiphenylmethane, 4-amino-4'-hydroxydiphenylsulfide, 4,4 '
-Diaminophenyl sulfide (thiodianiline),
4,4'-diaminodiphenylsulfone, 2,5-diaminotoluene, 4,4'-ethylenedianiline, 4,4'-diaminodiphenoxyethane, 4,4'-diaminodiphenylmethane (methylenedianiline), 4'-diaminodiphenyl ether (oxydianiline) and the like.

The thermotropic liquid crystal polymer used in the present invention can be produced from the above monomers by various ester forming methods such as a melt acidilysis method and a slurry polymerization method. Of thermotropic liquid crystal polymers obtained from these monomers, the aromatic polyester is preferably a monomer unit represented by the general formula of 4 a polymer or copolymer comprising as essential components.

[0016]

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Particularly preferred wholly aromatic polyesters of the present invention, p- hydroxybenzoic acid, polyesters represented by having Formula 5 repeating units derived from each of three compounds of phthalic acid and biphenol or, p-
Of having repeating units derived from each of two compounds of hydroxybenzoic acid and hydroxynaphthoic acid
The polyester represented by No. 6 .

[0018]

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The inorganic powder used in the present invention includes:
Mohs hardness used for hardness testing of minerals and the like must be in the range of 2 to 4. Specific examples of inorganic substances having a Mohs hardness of 2 to 4 include metals such as zinc, gold, silver, aluminum, copper, brass, antimony, and phosphor bronze, kaolinite, rock salt, silvin, mica (silica mica, kin mica), and shinsha. , Pyrolusite, polybasite,
Brucite, borax, carnallite, cryolite, amberite, galena, scotch ore, veneerite, calcite, marble, gypsum, celestite, harinickelite, rhododrite, sphalerite, peacock stone, dolomite, Natural products such as kihuite, rhodochroite, fluorite, gyrite, jammonite, clay, sericite, aluminum hydroxide, molybdenum disulfide, zinc oxide, calcium sulfate,
Examples include calcium carbonate and potassium titanate. Of these, calcium sulfate and calcium carbonate are preferably used. When a material that does not fall within the range of Mohs hardness of 2 to 4 is used, for example, when talc having a Mohs hardness of 1 is used, even if a soft material is selected as the mating material, the resin composition is worn. Conversely, when wollastonite (calcium metasilicate) having a Mohs hardness of 4.5 is used, there is a problem that the plastic as a mating material is worn.

The shape of the inorganic substance having a Mohs hardness of 2 to 4 used in the present invention must be a powder. In the present invention, the term “granule” refers to a powder that does not spread in a specific direction, unlike a fiber, plate, or strip shape, and has a ratio of major axis / minor axis (hereinafter, referred to as aspect ratio). It is a powder of about 4 or less, preferably 1 to 3. The average particle size is 0.01 μm to 1 mm, preferably 0.1 to 100.
μm, more preferably 1 to 50 μm. Even inorganic materials having a Mohs' hardness of 2 to 4 can be used, for example, in a fibrous or flat shape and not in the form of powder or granules but having an aspect ratio of more than 4. When the movement involves eccentric rotation, reciprocating vibration, or other complicated movement, the effects of the present invention cannot be sufficiently obtained, which is not preferable.

The amount of the inorganic powder having a Mohs hardness of 2 to 4 used in the present invention is determined by the amount of the thermotropic liquid crystal polymer 1
It must be in the range of 20 to 130 parts by weight with respect to 00 parts by weight. When the amount is less than 20 parts by weight with respect to 100 parts by weight of the thermotropic liquid crystal polymer, the abrasion resistance is not sufficient, and when the amount exceeds 130 parts by weight, the wear resistance is not significantly improved. It is not preferable because the mechanical strength of the obtained resin composition is reduced.

As long as the effects of the present invention are not impaired, a filler other than the inorganic powder having a Mohs' hardness of 2 to 4 can be added. Examples of these fillers include inorganic fillers other than the inorganic powder having a Mohs hardness of 2 to 4, organic fillers, stabilizers, ultraviolet absorbers, pigments, dyes, modifiers, and the like.

Of these, inorganic fillers are particularly important, and are often used for improving workability, mechanical strength, heat resistance, etc. in addition to wear characteristics. Examples of the inorganic filler other than the inorganic powder having a Mohs hardness of 2 to 4 include an inorganic powder having a Mohs hardness outside the above range or a fibrous or plate-like inorganic filler having no powder-particle shape. Specific examples include glass fibers (Mohs hardness: 6.5), fibrous materials such as carbon fibers and aramid fibers, various whiskers such as zinc oxide and potassium titanate, and graphite (Mohs hardness: 1-2). ), Glassy carbon, talc (Mohs hardness:
1), calcium silicate (Mohs hardness: 4.5), silica (Mohs hardness: 7), alumina (Mohs hardness: 9), fluorinated graphite and the like.

Further, examples of the organic filler include various thermoplastic resins and thermosetting resins. In particular, a fluororesin is effective in improving abrasion characteristics such as a reduction in friction coefficient, and when added, 5 to 50 parts by weight per 100 parts by weight of the thermotropic liquid crystal polymer is preferable. Examples of such a fluororesin include a homopolymer of tetrafluoroethylene (hereinafter abbreviated as “PTFE”).

The method of mixing the thermotropic liquid crystal polymer, the inorganic powder having a Mohs hardness of 2 to 4, and the other fillers is not particularly limited, and various known mixing means can be applied. it can. For example, they may be separately supplied to an extruder and melt-mixed, or may be preliminarily mixed by a mixer such as a Henschel mixer or a tumbler and then supplied to the extruder. The member of the present invention thus obtained is molded by a method such as injection, compression, or extrusion. In the case of compression molding, each may be dry-blended and molded in powder form.

The plastic of the mating material on the sliding surface of the sliding member of the present invention is not particularly limited, and known thermoplastic and thermosetting plastics are used. Examples of these plastics include polyethylene, polyolefins such as polypropylene, polyacetal, polystyrene, polyvinyl chloride, polyacrylate,
Examples thereof include polyester, polyamide, polycarbonate, and polyphenylene oxide. Among them, phenolic resins having relatively high heat resistance; thermoplastic polyamide imides and polyether imides, etc .; and wholly aromatics obtained by a condensation polymerization reaction of non-thermoplastic aromatic diamine and aromatic tetracarboxylic acid. Polyimide such as polyimide; for example, polyphenylene sulfide produced by reacting p-dichlorobenzene with sodium sulfide; polysulfone; polyether sulfone; fluororesin; a thermotropic liquid crystal polymer such as wholly aromatic polyester is used as a mating material. In some cases, the heat resistance, which is one of the features of the member of the present invention, is synergistically exhibited. Further, among these, polyimide, particularly wholly aromatic polyimide, is preferably used. As a sliding member as a mating member, any of various shapes obtained by a known molding method such as injection molding can be used. However, the effect of the present invention is particularly large in the case of a film shape such as a polyimide film. As these plastics as mating materials, those in which the above-mentioned various fillers are appropriately blended can also be used.

Since the member of the present invention has excellent slidability and abrasion resistance, (1) shafts, bearings, gears, cams, bearings, etc. of electric appliances, office equipment and power equipment, (2) video Guide rolls for tapes and cassette tapes, (3) Heater holders for printers and copiers, separation claws, etc. (4) End face materials for mechanical seals, tip seals for scroll compressors, valve seats for valves, V-rings, rod packing, (5) It can be used for a rotating shaft, a rotating sleeve, a piston, an impeller, a vane, a rotor, a roller, etc. of a compressor.

[0028]

The present invention will be described in more detail with reference to the following examples. First, raw materials used in Examples and Comparative Examples are collectively shown below. (1) Thermotropic liquid crystal polymer (A) A powder of a thermotropic liquid crystal polymer which is a quaternary copolyester of terephthalic acid, isophthalic acid, 4-hydroxybenzoic acid and 4,4′-dihydroxydiphenyl. 350 ° C by DSC. (B) A powder of a thermotropic liquid crystal polymer which is a ternary copolyester of terephthalic acid, 4-hydroxybenzoic acid and 4,4′-dihydroxydiphenyl. DSC
420 ° C. (2) Calcium sulfate (trade name: CAS-20, U.S.A.)
Mohs hardness: 2-3 Granular powder (average particle size: 1.5-3.0 μm, aspect ratio: 1-3) (3) Calcium carbonate (trade name: KS-500, Dowa Cal) Mohs hardness: 3 to 4 Granular powder (average particle size: 5 μm, aspect ratio: 1 to 2) (4) Wollastonite (trade name: NYAD G, NYCO, USA) Mohs hardness: 4. 5 Fibrous (aspect ratio: 10) (5) Glass fiber (trade name: Milled glass fiber MFA, manufactured by Asahi Fiber Glass Co., Ltd.) Mohs hardness: 6.5 Fibrous (diameter: 10 to 15 μm, length: 30 to 100 μm) (6) Talc (trade name: Mistron 850FC, manufactured by Nippon Mistron Co., Ltd.) Mohs hardness: 1 plate-like powder (average particle size: 45 μm, aspect ratio: 1 to 1)
3) (7) Fluororesin (PTFE; trade name: KT-400)
M, manufactured by Kitamura Co., Ltd.)

<Example 1> The above-mentioned materials were blended in the proportions shown in Table 1, mixed with a Henschel mixer, and then melted using a twin-screw extruder (PCM-30, manufactured by Ikegai Iron Works Co., Ltd.). The mixture was kneaded (cylinder temperature 420 ° C., screw rotation speed 200 rpm) and granulated into pellets. Next, using an injection molding machine (Nestal SG25 type, manufactured by Sumitomo Heavy Industries, Ltd.) from the pellets, under the conditions of a cylinder temperature of 400 ° C., an injection pressure of 1,000 kgf / cm ² and a mold temperature of 150 ° C.
A cylinder having an outer diameter of 25.6 mm and an inner diameter of 20 mm was formed. The obtained cylinder was subjected to a pressure of 2 kgf / c using a Suzuki friction and wear tester.
Using a wholly aromatic polyimide film as a mating member under conditions of m ² and a speed of 20 m / min, the abrasion amount and friction coefficient of the cylinder and the polyimide film were measured. On the other hand, a bending test piece was molded under the same conditions using the injection molding machine described above, and the obtained test piece was used to determine the bending strength according to ASTM D 790 and the load 18.5 kgf / cm ^{2 according} to ASTM D 648.
The heat distortion temperature was measured under the following conditions. Table 1 shows the results.

<Examples 2 and 3> The above-mentioned materials were blended in the ratios shown in Table 1, mixed with a Henschel mixer, and then used with a twin-screw extruder (PCM-30, manufactured by Ikegai Iron Works Co., Ltd.). The mixture was melt-kneaded (cylinder temperature: 350 ° C., screw rotation speed: 200 rpm) and granulated into pellets. Next, using an injection molding machine (Nestal SG 25 type, manufactured by Sumitomo Heavy Industries, Ltd.), the pellet temperature was 350
° C., injection pressure 1,000 kgf / cm ^2, at a mold temperature of 80 ° C., and molding the cylinder as in Example 1, was measured wear characteristics. Further, a bending test piece was molded under the same conditions using the above-described injection molding machine, and the bending strength and the heat distortion temperature were measured using the obtained test piece. Table 1 shows the results.

[0031]

[Table 1]

<Comparative Example 1> The above-mentioned materials were blended in the proportions shown in Table 2, pellets were granulated in the same manner as in Example 1, and cylindrical and bending test pieces were formed and evaluated. Table 2 shows the results.

<Comparative Examples 2 to 5> The above-mentioned materials were blended in the proportions shown in Table 2, pellets were granulated in the same manner as in Example 2, and cylinders and bending test pieces were formed and evaluated. Table 2 shows the results.

[0034]

[Table 2]

As can be seen from the results in Tables 1 and 2,
In Examples 1 to 3, since the ratios of the thermotropic liquid crystal polymer and the inorganic particles having a Mohs' hardness of 2 to 4 are all within the desired ranges, both the abrasion characteristics and the mechanical strength are excellent. On the other hand, in Comparative Examples 1 to 3, since the Mohs hardness of the filler is out of the range of 2 to 4, the results show that the amount of self wear or the amount of wear of the mating material is large. In Comparative Example 4, since the amount of the inorganic powder was too large relative to the thermotropic liquid crystal polymer, the bending strength and the heat distortion temperature were low. In Comparative Example 5, the amount of the inorganic powder was too small.
Insufficient wear resistance.

[0036]

Member of the present invention exhibits, in order to have the following characteristics, plus used in sliding parts used at high temperatures
Most suitable as a sliding member for tics . (1) Since a polymer having a particularly high melting point is used among conventional plastics, melting, seizure, and the like due to frictional heat during sliding hardly occur. (2) Since one of the components is an inorganic powder having a Mohs' hardness of 2 to 4 and is relatively soft, even if a plastic member such as a plastic film is used as a sliding partner, these components are hardly damaged. (3) Since the thermotropic liquid crystal polymer is used, although it has a high melting point, it has good fluidity at the time of melting, so that injection molding of the composition is easy.

Continued on the front page (51) Int.Cl. ⁷ Identification code FI C10M 103: 06 107: 38) C10N 10:04 10:14 20:00 20:06 30:06 30:08 40:02 50:08

Claims (3)

(57) [Claims] An inorganic powder of calcium sulfate and / or calcium carbonate having 100 parts by weight of a thermotropic liquid crystal polymer which is a polymer or a copolymer containing a monomer unit represented by the following general formula 1 and a Mohs' hardness of 2 to 4. A sliding member for plastics comprising 20 to 130 parts by weight of granules. Embedded image 2. An inorganic powder of calcium sulfate and / or calcium carbonate having a Mohs hardness of 2 to 4 and 100 parts by weight of a thermotropic liquid crystal polymer which is a polymer or a copolymer containing a monomer unit represented by the following general formula 2. Injection molding a resin composition consisting of 20 to 130 parts by weight of granules
Plastic sliding member made. Embedded image 3. The thermotropic liquid crystal polymer,
The sliding member for plastic according to claim 1, which is a wholly aromatic polyester.