JP2022139101A - Liquid composition and sliding member - Google Patents

Abstract

To provide a liquid composition which is excellent in dispersion stability and coating property, enables formation of a sliding film that has high slidability in addition to low friction and heat resistance as an obtained molded article (burned article) and is excellent in adhesion to a member and abrasion durability, and contains particles of a tetrafluoroethylene-based polymer.SOLUTION: A liquid composition for sliding film formation contains particles of a tetrafluoroethylene-based polymer containing particles of a heat-fusible tetrafluoroethylene-based polymer, particles of an abrasion modifier, an imide-based resin, and a liquid dispersion medium, wherein an average particle diameter of the particles of the heat-fusible tetrafluoroethylene-based polymer is smaller than an average particle diameter of the particles of the abrasion modifier, a ratio of the tetrafluoroethylene-based polymer to the total amount of the imide-based resin and the tetrafluoroethylene-based polymer is more than 50 mass%, and viscosity is 10,000 mPa s or less.SELECTED DRAWING: None

Description

The present invention relates to a liquid composition useful for forming a sliding coating, comprising particles of a predetermined tetrafluoroethylene-based polymer, particles of a wear modifier, and an imide-based resin.

Wind power generators are often installed near the coast because they can easily obtain wind direction and wind force stably. High weather resistance against sea breeze is required. In addition, the total length of the tower that supports the nacelle may be 30 m or more, making normal maintenance difficult. Therefore, a yaw bearing with excellent weather resistance and long life is required.
Polytetrafluoroethylene (PTFE) is known as a material with excellent weather resistance, low friction properties, and slidability. PTFE has a low coefficient of friction and is excellent in slipperiness, but it is easily worn due to its low strength, and its adhesion to metal is weak. Therefore, various proposals have been made from the viewpoint of improving the adhesion of PTFE to the substrate and the wear resistance.

Patent Document 1 discloses a sliding member having a resin composition layer containing polyamideimide and PTFE on the surface of a porous sintered substrate. Patent Document 2 discloses a yaw bearing that rotatably supports a nacelle of a wind power generator, having a resin layer containing PTFE, a friction modifier, and a binder resin. In Patent Document 3, a base layer containing a heat-resistant resin and a fluorine primer resin is applied to the surface of a metal substrate, and a non-thermally fusible PTFE is applied to the surface of the base layer to form a crosslinked layer. A sliding member for a compressor having a sliding layer is disclosed.

WO2008/047561 JP 2008-303914 A JP 2020-056330 A

The sliding layers in Patent Documents 1 and 2 are still insufficient in slidability, and when the amount of PTFE added is increased in order to lower the coefficient of friction and improve the slidability, the adhesion to the substrate is reduced. There was a problem of putting it away. Since the sliding layer in Patent Document 3 is made of non-thermally fusible PTFE, it has low adhesion to the base material and is still insufficient in abrasion resistance even after cross-linking.

As a result of intensive studies, the present inventors have found that a tetrafluoroethylene-based polymer particle containing hot-melt tetrafluoroethylene-based polymer particles, a wear modifier particle, and an imide-based resin are contained, It has been found that a liquid composition in which the particle size of the particles, the content of the tetrafluoroethylene-based polymer, and the content of the imide-based resin are within specific ranges is excellent in dispersion stability and coatability. In addition, the inventors have found that a molded article obtained from such a liquid composition is dense, has high slidability, is excellent in abrasion resistance, and has improved adhesion to a substrate.
An object of the present invention is to provide a liquid composition that is excellent in dispersion stability and coatability, has low friction properties, heat resistance, and high slidability, and can form a sliding coating that is excellent in adhesion to members and abrasion resistance. A composition is provided.

The present invention has the following aspects.
[1] The heat-fusible tetrafluoroethylene-based polymer particles containing particles of a heat-fusible tetrafluoroethylene-based polymer, particles of a wear modifier, an imide-based resin, and a liquid dispersion medium, The average particle diameter of the fluoroethylene-based polymer particles is smaller than the average particle diameter of the wear modifier particles, and the ratio of the tetrafluoroethylene-based polymer to the total amount of the imide-based resin and the tetrafluoroethylene-based polymer. is more than 50% by mass, and the viscosity is 10,000 mPa·s or less, for forming a sliding coating.
[2] The liquid composition of [1], wherein the hot-melt tetrafluoroethylene-based polymer has a melting temperature of 200 to 320°C.
[3] The liquid composition of [1] or [2], wherein the hot-melt tetrafluoroethylene-based polymer is a tetrafluoroethylene-based polymer having an oxygen-containing polar group.
[4] The liquid composition according to any one of [1] to [3], wherein the hot-melt tetrafluoroethylene polymer particles have an average particle size of 0.1 to 25 μm.
[5] The liquid composition according to any one of [1] to [4], wherein the imide resin is an aromatic polyimide, an aromatic polyamideimide, or a precursor thereof.
[6] The liquid composition according to any one of [1] to [5], wherein the imide resin is dissolved in the liquid dispersion medium.
[7] The particles of the wear modifier are glass particles, glass fiber pulverized particles, alumina particles, silica particles, talc particles, graphite particles, coke particles, carbon black particles, carbon fiber pulverized particles, bronze (bronze) particles, The liquid composition according to any one of [1] to [6], which is at least one selected from the group consisting of molybdenum sulfide particles, polyimide particles, and polyphenylene sulfide particles.
[8] The liquid composition according to any one of [1] to [7], wherein the liquid dispersion medium is water.
[9] [1] to [8], wherein the ratio of the average particle size of the particles of the wear modifier to the average particle size of the particles of the hot-melt tetrafluoroethylene-based polymer is in the range of 2 to 40; The liquid composition of any of
[10] The liquid composition according to any one of [1] to [9], wherein the weight ratio of the tetrafluoroethylene-based polymer to the total weight of the imide-based resin and the tetrafluoroethylene-based polymer is 80% by mass or less. thing.
[11] Any one of [1] to [10], wherein the total content of the tetrafluoroethylene-based polymer particles and the imide-based resin is 20% by mass or more relative to the total mass of the liquid composition. Liquid composition.
[12] of [1] to [11], wherein the content of the particles of the wear modifier is in the range of 0.05 to 1 with respect to the total content of the imide-based resin and the tetrafluoroethylene-based polymer; Any liquid composition.
[13] The liquid composition of any one of [1] to [12], further comprising a nonionic surfactant.
[14] A sliding member comprising a substrate and a coating formed on the surface of the substrate and formed from the liquid composition according to any one of [1] to [13].
[15] The sliding member of [14], which is a bearing.

ADVANTAGE OF THE INVENTION According to this invention, the liquid composition of a tetrafluoroethylene-type polymer excellent in dispersion stability and coatability can be provided. Further, from the liquid composition of the present invention, it is possible to form a sliding coating having low friction, heat resistance, and high slidability, as well as excellent adhesion to members and wear resistance. Therefore, the liquid composition of the present invention is useful as a film-forming material for various sliding members such as bearings.

The following terms have the following meanings.
"Average particle diameter (D50)" is the volume-based cumulative 50% diameter of the object (particles) determined by the laser diffraction/scattering method. That is, the particle size distribution is measured by a laser diffraction/scattering method, and the cumulative curve is obtained with the total volume of the group of particles being 100%.
The D50 of the object is obtained by dispersing particles in water and analyzing them by a laser diffraction/scattering method using a laser diffraction/scattering particle size distribution analyzer (LA-920 measuring instrument manufactured by Horiba, Ltd.).
"Melting temperature (melting point)" is the temperature corresponding to the maximum melting peak of the polymer as measured by differential scanning calorimetry (DSC).
“Viscosity” is determined by measuring a liquid composition using a Brookfield viscometer at 25° C. and a rotation speed of 30 rpm. The measurement is repeated 3 times, and the average value of the 3 measurements is taken.
The “thixotropic ratio” is a value calculated by dividing the viscosity η ₁ of a liquid composition measured at a rotation speed of 30 rpm by the viscosity η ₂ measured at a rotation speed of 60 rpm. . Each viscosity measurement is repeated three times, and the average value of the three measurements is taken.
A "unit" in a polymer means an atomic group based on the monomer formed by polymerization of the monomer. The units may be units directly formed by a polymerization reaction, or may be units in which some of said units have been converted to another structure by treatment of the polymer. Hereinafter, units based on monomer a are also simply referred to as "monomer a units".

The liquid composition of the present invention (hereinafter also referred to as "this composition") comprises particles (hereinafter referred to as "melting F particles") of a heat-melting tetrafluoroethylene-based polymer (hereinafter also referred to as "melting F polymer"). ”) containing particles of a tetrafluoroethylene polymer (hereinafter also referred to as “F polymer”) (hereinafter also referred to as “F particles”), particles of a wear modifier, an imide resin, and a liquid dispersion medium, the average particle size of the molten F particles is smaller than the average particle size of the particles of the wear modifier, and the ratio of the F polymer to the total amount of the imide resin and the F polymer is A liquid composition for forming a sliding coating, which is more than 50% by mass and has a viscosity of 10,000 mPa·s or less.

The composition has excellent dispersion stability and coatability. In addition, the polymer layer (baked product) formed from the present composition and used as a sliding coating has excellent physical properties such as low friction and heat resistance based on the tetrafluoroethylene-based polymer and has high slidability. In addition, it is excellent in adhesion to members and abrasion resistance, and can be suitably used as a sliding film constituting a sliding member. The reason why these properties are exhibited and the mechanism of action are not necessarily clear, but are presumed, for example, as follows.

A tetrafluoroethylene-based polymer tends to aggregate in a liquid dispersion medium due to its low surface tension. Therefore, it is difficult to adjust liquid physical properties such as viscosity and thixotropic ratio of a liquid composition containing F particles, and it is difficult to balance dispersion stability and coatability. In the case of forming a sliding film in which F particles and a wear modifier are held in a binder resin on the surface of a substrate to form a sliding member, increasing the amount of F particles in order to improve slidability improves the sliding film. While the adhesion to the substrate is lowered, if the amount of F particles is reduced to ensure the adhesion, the slidability is lowered. Therefore, it is difficult to obtain a liquid composition that is excellent in liquid physical properties such as dispersion stability and coatability and that can form a sliding coating with well-balanced physical properties such as high slidability, high adhesion, and abrasion resistance. It was difficult.

In this composition, the molten F polymer is essential as the F polymer, and the amount of the imide resin blended is small relative to the molten F polymer, so the imide resin acts both as a binder resin and as a dispersant for the F particles. It is believed that this enhances the dispersion stability and coatability of the present composition. Furthermore, in the present composition, the average particle size of the molten F particles is adjusted to be smaller than the average particle size of the particles of the wear modifier, and the content of the imide resin is adjusted to be smaller than the content of the F polymer. , promoting interactions such as adsorption among the particles of the molten F particles, the imide resin, and the wear modifier, buffering the shearing force applied to the F particles during preparation of the present composition, and suppressing the aggregation of the F particles. presumed to be
It is presumed that when a slide coating is formed from this composition, which has excellent dispersion stability and coatability, the tetrafluoroethylene-based polymer, the imide-based resin, and the wear modifier are likely to be distributed densely and uniformly in the slide coating. be done. As a result, it is presumed that a sliding film having excellent slidability, high adhesion and abrasion resistance was formed.

The F particles in the present composition include particles of molten F polymer (fused F particles). The F particles may consist only of molten F particles, and particles of molten F polymer and non-thermally fusible tetrafluoroethylene-based polymer (hereinafter also referred to as "non-melting F polymer") (hereinafter referred to as "non-melting F polymer"). Also referred to as "meltable F particles").
In the latter case, the content of non-melting F particles in the total amount of F particles is preferably less than 50% by mass.
The non-melting F polymer is a polymer that does not have a melting temperature, or has a melting temperature and a load of 49 N at a temperature that is 20° C. or more higher than the melting temperature of the polymer, and the melt flow rate is 1 g/g. It means that the polymer does not have a temperature of 10 minutes or more. Preferably, the non-melting F-polymer is a non-thermal melting polytetrafluoroethylene.
Also, D50 of the non-melting F particles is preferably 0.1 to 1 μm.

The melt F polymer in the present composition is a hot melt polymer containing units based on tetrafluoroethylene (TFE) (TFE units). By being heat-meltable, a sliding coating (hereinafter also referred to as a “sliding coating”), which is a molded product (baked product) such as a polymer layer formed from the composition, has flexibility and a base material. It is easy to have excellent adhesiveness and adhesion with. The term "thermally fusible" means a melt-fluid polymer having a melt flow rate of 1 to 1000 g/10 minutes at a temperature higher than the melting temperature of the polymer by 20°C or more under a load of 49 N. .
The melting temperature of the molten F polymer is preferably 200-320°C, more preferably 260-320°C. In such a case, the sliding coating formed from the present composition tends to have excellent heat resistance.

The fluorine atom content in the molten F polymer is preferably 70% by mass or more, more preferably 70 to 76% by mass.
The glass transition point of the molten F polymer is preferably 75 to 125°C, more preferably 80 to 100°C.

As molten F polymers, polymers containing TFE units and units based on ethylene (ETFE), polymers containing TFE units and units based on perfluoro(alkyl vinyl ether) (PAVE) (PAVE units) (PFA), TFE units and hexafluoro Polymers (FEP) containing units based on propene (HFP) are mentioned. Each of ETFE, PFA and FEP may further contain other units. Preferably, the molten F-polymer is PFA or FEP, more preferably PFA. PAVE is preferably CF ₂ =CFOCF ₃ , CF ₂ =CFOCF ₂ CF ₃ and CF ₂ =CFOCF ₂ CF ₂ CF ₃ (PPVE), more preferably PPVE.

The molten F polymer preferably has oxygen-containing polar groups. In this case, since the affinity between the molten F polymer and the imide resin is improved, the present composition tends to be excellent in dispersion stability. In this case, it is thought that the molten F polymer reacts with the imide resin to form a crosslinked structure when the present composition is heated. It is thought that physical properties such as adhesiveness and adhesion to the substrate are even more excellent.
The oxygen-containing polar group may be contained in a unit in the molten F polymer, or may be contained in a terminal group of the main chain of the molten F polymer. In the latter mode, a molten F polymer having an oxygen-containing polar group as a terminal group derived from a polymerization initiator, a chain transfer agent, or the like, or an oxygen-containing polar group obtained by plasma treatment or ionizing radiation treatment of the molten F polymer. A molten F polymer having The oxygen-containing polar group is preferably a hydroxyl group-containing group, a carbonyl group-containing group and a phosphono group-containing group, more preferably a hydroxyl group-containing group and a carbonyl group-containing group from the viewpoint of the dispersion stability of the present composition, and a carbonyl group-containing group. More preferred.

The hydroxyl group-containing group is preferably a group containing an alcoholic hydroxyl group, more preferably -CF ₂ CH ₂ OH, -C(CF ₃ ) ₂ OH and 1,2-glycol group (-CH(OH)CH ₂ OH). .
A carbonyl group-containing group is a group containing a carbonyl group (>C(O)), and includes a carboxyl group, an alkoxycarbonyl group, an amide group, an isocyanate group, a carbamate group (-OC(O)NH ₂ ), an acid anhydride residue, Groups (-C(O)OC(O)-), imide residues (-C(O)NHC(O)-, etc.) and carbonate groups (-OC(O)O-) are preferred, and acid anhydride residues is more preferred.
When the molten F polymer has a carbonyl group-containing group, the number of carbonyl group-containing groups in the molten F polymer is preferably 10 to 5000, more preferably 100 to 3000, per 1×10 ⁶ carbon atoms in the main chain. , more preferably 800 to 1500. The number of carbonyl group-containing groups in the molten F polymer can be quantified by the composition of the polymer or the method described in WO2020/145133.

The molten F polymer is preferably a polymer having an oxygen-containing polar group containing TFE units and PAVE units, more preferably a polymer containing units based on a monomer having a TFE unit, a PAVE unit and an oxygen-containing polar group. Polymers containing 90 to 99 mol %, 0.5 to 9.97 mol % and 0.01 to 3 mol % of these units in this order with respect to all units are more preferable.
The monomer having an oxygen-containing polar group is preferably itaconic anhydride, citraconic anhydride or 5-norbornene-2,3-dicarboxylic anhydride (hereinafter also referred to as "NAH").
Specific examples of such polymers include those described in WO2018/16644.
The particles of these molten F polymers not only have excellent dispersion stability, but also tend to be densely and homogeneously distributed in the sliding coating formed from the present composition. Furthermore, microspherulites are likely to be formed in the sliding coating, and adhesion to other components is likely to be enhanced. As a result, it is easier to obtain a sliding coating excellent in various physical properties such as high slidability, abrasion resistance, and adhesion to members.

In the composition, the D50 of the fused F particles is preferably 0.1 to 25 μm. D50 of the molten F particles is preferably 20 μm or less, more preferably 10 μm or less, and even more preferably 8 μm or less. D50 of the molten F particles is preferably 0.1 μm or more, more preferably 1 μm or more, and even more preferably 2 μm or more. In this range of D50, the molten F particles tend to have good fluidity and dispersion stability.

From the viewpoint of the dispersion stability of the present composition, the bulk density of the fused F particles is preferably 0.15 g/m ² or more, more preferably 0.20 g/m ² or more. The bulk density of the molten F particles is preferably 0.50 g/m ² or less, more preferably 0.35 g/m ² or less.
Further, the specific surface area of the fused F particles is preferably 1 to 8 m ² /g, more preferably 1 to 3 m ² /g.

The molten F particles may contain a resin or an inorganic filler other than the molten F polymer, but preferably contain the molten F polymer as a main component. The content of the molten F polymer in the molten F particles is preferably 80% by mass or more, more preferably 100% by mass.
Examples of the resin include heat-resistant resins such as aromatic polyesters, polyamideimides, (thermoplastic) polyimides, polyphenylene ethers, polyphenylene oxides, and maleimides. Examples of inorganic fillers include silicon oxide (silica), metal oxides (beryllium oxide, cerium oxide, alumina, soda alumina, magnesium oxide, zinc oxide, titanium oxide, etc.), boron nitride, and magnesium metasilicate (steatite). . At least part of the surface of the inorganic filler may be surface-treated.
The molten F particles containing a resin other than the molten F polymer or an inorganic filler have a core-shell structure in which the core is the molten F polymer and the shell is a resin other than the molten F polymer or the inorganic filler, or the molten F polymer is used as the shell. , it may have a core-shell structure having a resin other than the molten F polymer or an inorganic filler in the core. Such molten F particles are obtained, for example, by coalescing (colliding, aggregating, etc.) particles of molten F polymer and particles of resin or inorganic filler other than molten F polymer.

In the present composition, the particles of the wear modifier have the role of improving the wear resistance of the sliding coating formed from the composition and improving the friction characteristics by imparting a frictional force to the sliding coating. .
Particles of the wear modifier include glass particles, ground glass fiber particles, alumina particles, silica particles, zinc oxide particles, titanium oxide particles, iron oxide particles, talc particles, potassium titanate particles, magnesium borate particles, and calcium sulfate particles. , magnesium sulfate particles, wollastonite particles, graphite particles, coke particles, carbon black particles, carbon fiber crushed particles, graphite fluoride particles, silicon carbide particles, boron nitride particles, mica particles, bronze (bronze) particles, lead particles, Inorganic particles such as zinc particles, copper particles, molybdenum disulfide particles, tungsten disulfide particles; crosslinked ultra high molecular weight polyethylene particles, crosslinked high density polyethylene particles, polyimide particles, polyphenylene sulfide particles, PTFE particles, melamine sia Examples include organic particles such as nurate particles. These may be used individually by 1 type, and may use 2 or more types together.

In the present composition, from the viewpoint of the slidability and wear resistance of the sliding coating formed from the present composition, the particles of the wear modifier are glass particles, ground glass fiber particles, alumina particles, silica particles, talc. It is preferably at least one selected from the group consisting of particles, graphite particles, coke particles, carbon black particles, ground carbon fiber particles, bronze (bronze) particles, molybdenum disulfide particles, polyimide particles, and polyphenylene sulfide particles.

At least a portion of the surface of the particles of the wear modifier contains a silane coupling agent (3-aminopropyltriethoxysilane, vinyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane). silane, 3-methacryloxypropyltriethoxysilane, 3-isocyanatopropyltriethoxysilane, etc.).

In the composition, the D50 of the wear modifier particles is preferably between 0.1 and 100 μm. The D50 of the particles of the wear modifier is preferably 90 μm or less, more preferably 80 μm or less, and even more preferably 50 μm or less. The D50 of the particles of the wear modifier is preferably 0.5 μm or more, more preferably 1 μm or more, and even more preferably 2 μm or more. In this range of D50, the fluidity and dispersibility of the particles of the wear modifier tend to be good.
The shape of the particles of the wear modifier may be granular, needle-like (fibrous), or plate-like. Specific shapes of the particles of the wear modifier include spherical, scale-like, layer-like, leaf-like, apricot kernel-like, columnar, crest-like, equiaxed, leaf-like, mica-like, block-like, tabular, wedge-like, and rosette-like. shape, mesh shape, and prismatic shape.

In this composition, the D50 of the fused F particles is less than the D50 of the wear modifier. The ratio of the D50 of the wear modifier particles to the D50 of the fused F particles is preferably in the range of 2-40. The ratio is preferably 3 or more, more preferably 5 or more, from the viewpoints of the dispersion stability of the present composition and the adhesiveness, slidability and wear resistance of the sliding coating formed from the present composition. On the other hand, such a ratio is preferably 35 or less, more preferably 30 or less.

The imide resin constituting the present composition contributes to improving the dispersion stability of the present composition and improving the flexibility such as flex resistance of the sliding coating formed from the present composition. In addition, when the present composition is applied to the surface of a substrate to form a sliding coating containing molten F polymer, it contributes to the improvement of properties such as adhesiveness and adhesiveness between the sliding coating and the substrate.

Examples of imide-based resins include aromatic polyimides, aromatic polyimide precursors (polyamic acids or salts thereof), aromatic polyamideimides, aromatic polyamideimide precursors, modified aromatic polyimides having polar functional groups such as carboxylic acid groups, Examples include modified aromatic polyimide precursors, modified aromatic polyamideimides or modified aromatic polyamideimide precursors, aromatic polyetherimides and aromatic polyetherimide precursors.
Among them, aromatic polyimide or its precursor (polyamic acid or its salt), aromatic polyamideimide or its precursor are preferable.
In the present composition, the imide-based resin may be dispersed or dissolved in the liquid dispersion medium. is preferred. As will be described later, when water is used as a suitable liquid dispersion medium, the imide resin is preferably a water-soluble aromatic polyimide precursor or a water-soluble aromatic polyamideimide precursor. Group polyamideimide precursors are more preferred.

Examples of water-soluble aromatic polyimide precursors include polyamic acid obtained by polymerizing tetracarboxylic dianhydride and diamine in a solvent, and polyamic acid salt obtained by reacting the polyamic acid with aqueous ammonia or organic amine. . An aqueous solution of polyamic acid can be prepared by dissolving polyamic acid salt in water.
Tetracarboxylic dianhydrides include, for example, pyromellitic anhydride and biphenyltetracarboxylic anhydride. Examples of diamines include N,N'-diaminodiphenyl ether and p-diaminobenzene. Solvents include, for example, N-methylpyrrolidone and N,N-dimethylformamide.
Examples of organic amines include primary amines such as methylamine, ethylamine, n-propylamine, 2-ethanolamine, 2-amino-2-methyl-1-propanol; dimethylamine, 2-(methylamino)ethanol, 2 - secondary amines such as (ethylamino) ethanol; tertiary amines such as 2-dimethylaminoethanol, 2-diethylaminoethanol and 1-dimethylamino-2-propanol; 4 such as tetramethylammonium hydroxide and tetraethylammonium hydroxide and secondary ammonium salts.

The water-soluble aromatic polyamideimide resin or its precursor includes a polyamideimide resin obtained by reacting a diisocyanate and/or a diamine with a tribasic acid anhydride (or tribasic acid chloride) as an acid component, or its precursor. Precursors are included.
Examples of diisocyanates include 4,4′-diphenylmethane diisocyanate, xylylene diisocyanate, 3,3′-dimethylbiphenyl-4,4′-diisocyanate, 3,3′-diphenylmethane diisocyanate, 3,3′-dimethoxybiphenyl-4, 4′-diisocyanate, paraphenylene diisocyanate, hexamethylene diisocyanate, tolylene diisocyanate, naphthalene diisocyanate, tolylene diisocyanate, and isophorone diisocyanate. These diisocyanates may be used singly or in combination of two or more.
From the viewpoint of improving the stability of the aromatic polyamide-imide resin, a blocked isocyanate in which the isocyanate group is stabilized with a blocking agent may be used as the diisocyanate. Blocking agents include alcohols, phenols, oximes, and the like.

Examples of diamines include 3,3′-dimethylbiphenyl-4,4′-diamine, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenyl ether, 4,4′-diaminodiphenylsulfone, 3,3′- Diaminodiphenylsulfone, xylylenediamine, phenylenediamine, isophoronediamine. These diamines may be used singly or in combination of two or more.

Examples of tribasic acid anhydrides include trimellitic anhydride, and examples of tribasic acid chlorides include trimellitic anhydride chloride. As the tribasic anhydride, trimellitic anhydride is preferable from the viewpoint of reducing the load on the environment.

When producing an aromatic polyamideimide resin, in addition to the above tribasic acid anhydride (or tribasic acid chloride), dicarboxylic acid, tetracarboxylic dianhydride, etc. are added as an acid component to obtain the characteristics of the polyamideimide resin. may be used as long as it does not impair the
Dicarboxylic acids include, for example, terephthalic acid, isophthalic acid, adipic acid and sebacic acid. Tetracarboxylic dianhydrides include, for example, pyromellitic dianhydride, benzophenonetetracarboxylic dianhydride, and biphenyltetracarboxylic dianhydride. These may be used individually by 1 type, or may be used in combination of 2 or more types.

A water-soluble aromatic polyamide-imide resin or its precursor is obtained by copolymerizing the above diisocyanate and/or diamine and the above acid component in a polar solvent. Polar solvents include N-methyl-2-pyrrolidone, N-formylmorpholine, N-acetylmorpholine, N,N'-dimethylethyleneurea, N,N-dimethylacetamide, N,N-dimethylformamide, γ-butyrolactone and the like. is mentioned.

A water-soluble aromatic polyamideimide resin or its precursor is, for example, (1) an acid component and a diisocyanate component and/or a diamine component used at once and reacted; (2) an acid component and a diisocyanate component and/or Alternatively, a method of reacting with an excess amount of a diamine component to synthesize an amideimide oligomer having terminal isocyanate groups or amino groups, and then adding an acid component to react with terminal isocyanate groups and/or amino groups; 3) reacting an excess amount of an acid component with a diisocyanate component and/or a diamine component to synthesize an amideimide oligomer having an acid or acid anhydride group at its end, and then adding a diisocyanate component and/or a diamine component; It can be produced by a method of reacting with a terminal acid or acid anhydride group.

The number average molecular weight (Mn) of the water-soluble aromatic polyamideimide resin or its precursor is preferably 5,000 to 50,000, more preferably 25,000 or less. In this case, it is possible to secure the mechanical properties such as flex resistance of the sliding coating formed from the present composition.

Aromatic polyetherimides include amorphous polymers having imide bonds and ether bonds in the main chain, 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane and m- Polycondensates with phenylenediamine are preferred. Commercially available aromatic polyetherimides include, for example, "Ultem 1000F3SP" (manufactured by SABIC).

The acid value of the imide resin improves the dispersion stability of the F particles and wear modifier particles, improves the storage stability of the composition, and improves the adhesion of the sliding coating formed from the composition to the substrate. From the viewpoint of making it easier, it is preferably in the range of 20 to 100 mgKOH/g, more preferably 35 to 70 mgKOH/g. When the imide-based resin has an acid anhydride group, the acid value obtained when the acid anhydride group is ring-opened is defined as the acid value of the imide-based resin.

Incidentally, the above acid value is obtained, for example, by collecting about 0.5 g of an imide resin, adding about 0.15 g of 1,4-diazabicyclo[2.2.2]octane, and adding about 0.15 g of N-methyl-2-pyrrolidone. 60 g and about 1 ml of deionized water are added and stirred until the imide resin is completely dissolved. This can be measured by titration with a potentiometric titrator using a 0.05 mol/L ethanolic potassium hydroxide solution.

Preferred specific examples of imide-based resins include "HPC-1000" and "HPC-2100D" (both manufactured by Showa Denko Materials).

The ratio of the F polymer to the total amount of the imide resin and the F polymer in the present composition is more than 50% by mass. More preferably, the proportion is 60% by mass or more. Such a ratio is preferably 80% by mass or less, more preferably 70% by mass or less.
In this case, the dispersion stability of the present composition is improved, and physical properties such as slidability and friction durability of the sliding coating formed from the present composition are particularly likely to be improved. The reason for this is not necessarily clear, but the imide resin is highly likely to function as a dispersant and binder for the low hydrophilic F particles. This is believed to be due to the fact that the particles adhere to each other, and as a result, a dense sliding coating with excellent uniformity can be formed.

The total content of the F particles and the imide resin in the composition is preferably 20% by mass or more, more preferably 30% by mass or more, relative to the total mass of the composition. The total content is preferably 80% by mass or less, more preferably 60% by mass or less. A specific example of the preferred range of the total content is 30 to 80% by mass.
In this case, a sliding coating can be formed from the present composition with high uniformity, and the physical properties of the F polymer and the imide resin can be highly exhibited. That is, even if the content of the polymer component is in such a high range, the present composition has excellent dispersion stability and the slidability, adhesiveness, etc. of the formed sliding coating due to the mechanism of action described above. can improve the physical properties of

The content of the F particles in the composition is preferably 10% by mass or more, more preferably 20% by mass or more, relative to the total mass of the composition. The content of the F particles is preferably 80% by mass or less, more preferably 70% by mass or less, relative to the total mass of the present composition.
The content of the imide resin in the composition is preferably 1% by mass or more, more preferably 5% by mass or more, relative to the total mass of the composition. The content of the imide resin is preferably 30% by mass or less, more preferably 20% by mass or less.

The content of the wear modifier particles in the present composition is preferably in the range of 0.05 to 1, more preferably in the range of 0.08 to 0.5 with respect to the total content of the imide resin and the F polymer. and more preferably in the range of 0.1 to 0.3.
In this case, the dispersion stability and storage stability of the present composition are improved, and the polymer layer (baked product) formed from the present composition has high slidability, and furthermore, adhesion to members and abrasion resistance are improved. can be effectively used as a sliding coating for sliding members.

Liquid dispersion media in the present composition include compounds that are liquid at 25° C. under atmospheric pressure, such as aliphatic hydrocarbons, aromatic hydrocarbons, water, alcohols, ketones, amides and esters. , ketones, amides and esters are preferred. The boiling point of the liquid dispersion medium is preferably in the range of 50 to 240°C. Moreover, one type of the liquid dispersion medium may be used alone, or two or more types may be used in combination.

Alcohols include methanol, ethanol, isopropanol, glycol.
Ketones include acetone, methyl ethyl ketone, methyl isopropyl ketone, methyl isobutyl ketone, methyl n-pentyl ketone, methyl isopentyl ketone, 2-heptanone, cyclopentanone, cyclohexanone, cycloheptanone.
Amides include N-methyl-2-pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, N,N-dimethylpropanamide, 3-methoxy-N,N-dimethylpropanamide, 3-butoxy- N,N-dimethylpropanamide, N,N-diethylformamide, hexamethylphosphorictriamide, 1,3-dimethyl-2-imidazolidinone and the like.

Esters include methyl acetate, ethyl acetate, butyl acetate, methyl lactate, ethyl lactate, methyl pyruvate, ethyl pyruvate, methyl methoxypropionate, ethyl ethoxypropionate, ethyl 3-ethoxypropionate, γ-butyrolactone, γ- Valerolactone can be mentioned.

The content of the liquid dispersion medium in the composition is preferably 30 to 90% by mass, more preferably 50 to 80% by mass. Within this range, the dispersion stability and coatability of the present dispersion are likely to be improved.
Among them, it is preferable to use water as the liquid dispersion medium in the present composition. In this case, the present composition may further contain a water-soluble dispersion medium other than water as a dispersion medium. As such a water-soluble dispersion medium, water-soluble compounds that are classified as polar and liquid at 25° C. under atmospheric pressure are preferred. N-dimethylpropanamide, 3-butoxy-N,N-dimethylpropanamide, N-methyl-2-pyrrolidone.
The content of water in the present composition is preferably 40% by mass or more, more preferably 50% by mass or more. The water content is preferably 90% by mass or less, more preferably 80% by mass or less.
Within this range, the dispersion stability of the present composition is likely to be improved due to the mechanism of action described above.

The composition may further contain a surfactant from the viewpoint of improving dispersion stability and handleability. When the present composition contains a surfactant, it is preferred that the surfactant is nonionic and the hydrophilic portion of the surfactant has an oxyalkylene group or an alcoholic hydroxyl group. The oxyalkylene group may be composed of one type, or may be composed of two or more types. The oxyalkylene group is preferably an oxyethylene group.

The hydrophobic portion of the surfactant preferably has an alkyl group, acetylene group, polysiloxane group, perfluoroalkyl group or perfluoroalkenyl group.
The surfactant is preferably a glycol monoalkyl ether, an acetylenic surfactant, a silicone surfactant or a fluorosurfactant, more preferably a glycol monoalkyl ether or a silicone surfactant. The composition may contain a silicone surfactant and a glycol monoalkyl ether.
Specific examples of such surfactants include the "Ftergent" series (manufactured by Neos Co., Ltd. Ftergent is a registered trademark), the "Surflon" series (manufactured by AGC Seimi Chemical Co., Ltd. Surflon is a registered trademark), and the "Megafac" series ( Megafac manufactured by DIC Corporation is a registered trademark), "Unidyne" series (Unidyne manufactured by Daikin Industries, Ltd. is a registered trademark), "BYK-347", "BYK-349", "BYK-378", "BYK-3450" , “BYK-3451”, “BYK-3455”, “BYK-3456” (manufactured by BYK-Chemie Japan Co., Ltd.), “KF-6011”, “KF-6043” (manufactured by Shin-Etsu Chemical Co., Ltd.), “New Coal 1308" (manufactured by Nippon Nyukazai Co., Ltd.) and "Tergitol" series (manufactured by Dow Chemical Co., Ltd.).

When the dispersion further contains a surfactant, the amount thereof is preferably 1 to 15% by weight based on the total weight of the dispersion. In this case, the affinity between the components is enhanced, and the dispersion stability of the present dispersion is likely to be improved.

The composition in which the liquid dispersion medium is water may further contain an amine or ammonia. Amine or ammonia also has a role as a pH adjuster, and is considered to contribute to improving the dispersion stability and storage stability of the present composition. When the composition further comprises an amine or ammonia, its amount is preferably such that the pH of the composition is between 5 and 10.

Amines include dimethylamine, diethylamine, diisopropylamine, diethanolamine, triethanolamine, tripropanolamine, triethylamine, triamylamine, pyridine, N-methylmorpholine.
The composition in which the liquid dispersion medium is water may further contain a pH buffer. In this case, the pH stability of the present composition is improved, and the present composition tends to have excellent storage stability. Examples of pH buffers include tris(hydroxymethyl)aminomethane, ethylenediaminetetraacetic acid, ammonium hydrogencarbonate, ammonium carbonate and ammonium acetate.

The present composition may further contain a resin material other than the F polymer and the imide resin from the viewpoint of improving the adhesiveness and low linear expansion properties of the sliding coating formed from the present composition. Such resinous materials may be thermoset or thermoplastic, modified, dissolved in the composition, or dispersed without dissolution.
Examples of such resin materials include acrylic resins, phenol resins, liquid crystalline polyesters, liquid crystalline polyester amides, polyolefin resins, modified polyphenylene ethers, polyfunctional cyanate ester resins, polyfunctional maleimide-cyanate ester resins, polyfunctional maleimides, styrene aromatic elastomers such as elastomers, vinyl ester resins, urea resins, diallyl phthalate resins, melamine resins, guanamine resins, melamine-urea cocondensation resins, polycarbonates, polyarylates, polysulfones, polyallylsulfones, aromatic polyamides, aromatic poly Ether amide, polyphenylene sulfide, polyallyl ether ketone, polyphenylene ether, epoxy resin and the like.
When the composition further contains a resin material, the content thereof is preferably 40% by mass or less with respect to the mass of the entire composition.

A preferred embodiment of the resin material is an aromatic polymer. Preferably, the aromatic polymer is a polyphenylene ether or an aromatic elastomer (such as a styrene elastomer). In this case, not only is the adhesiveness and low linear expansion property of the sliding coating formed from the present composition further improved, but also the liquid physical properties (viscosity, thixotropic ratio, etc.) of the present composition are well balanced. easily improved.
Examples of styrene elastomers include copolymers of styrene and conjugated dienes or (meth)acrylic acid esters (styrene-butadiene rubbers, styrene core-shell copolymers, styrene block copolymers, etc.). A styrene elastomer that has both properties and is plasticized by heating to exhibit flexibility is preferred.

The composition may further comprise an inorganic filler different from the wear modifier particles. In this case, the sliding coating formed from the present composition tends to have excellent low linear expansion properties. Examples of the inorganic filler include those similar to the inorganic filler that may be contained in the F particles.

In addition to the above components, the present composition may contain a thixotropic agent, a viscosity modifier, an antifoaming agent, a silane coupling agent, a dehydrating agent, a plasticizer, a weathering agent, and an antioxidant within a range that does not impair the effects of the present invention. Other ingredients such as agents, heat stabilizers, lubricants, antistatic agents, brighteners, colorants, conductive agents, release agents, surface treatment agents, flame retardants, and various fillers may be further included.

The viscosity of the present composition is 10000 mPa·s or less, preferably 5000 mPa·s or less, more preferably 3000 mPa·s or less. The viscosity of the present composition is preferably 10 mPa·s or more, more preferably 50 mPa·s or more, and even more preferably 100 mPa·s or more. When the viscosity of the present composition is 10,000 mPa·s or less, it is excellent in coatability to the base material constituting the sliding member, and easily forms a homogeneous and dense sliding coating.

The thixotropic ratio of the present composition is preferably 1.0 or more. The thixotropic ratio of the present composition is preferably 3.0 or less, more preferably 2.0 or less. In this case, the present composition is excellent in coatability and uniformity, and easily forms a denser sliding coating.
When the present composition contains water as a liquid dispersion medium, the pH is preferably 5 to 10 from the viewpoint that the hue and long-term storage stability of the present composition tend to be excellent.

In the present composition, the dispersed layer ratio is preferably 60% or more, preferably 70% or more, and more preferably 80% or more. Here, the dispersed layer ratio is the composition (18 mL) placed in a screw tube (inner volume: 30 mL) and allowed to stand at 25 ° C. for 14 days. It is a value calculated by the following formula from the height and the height of the sedimentation layer (dispersion layer). If no sedimentation layer is observed after standing and there is no change in the state of the composition, it is assumed that there is no change in the height of the composition as a whole, and the dispersed layer ratio is 100%.
Dispersed layer ratio (%) = (height of sedimentation layer) / (height of entire composition) x 100

The composition can be prepared by mixing the F particles, the particles of the wear modifier, the imide resin, and the liquid dispersion medium. As a mixing method, the F particles, the wear modifier particles and the imide resin are added to the liquid dispersion medium all at once or sequentially, and mixed; the F particles, the wear modifier particles, the liquid dispersion medium, and the imide resin. A method of premixing each liquid dispersion medium and further mixing the obtained two kinds of mixtures; and the like. After pre-dispersing the F particles and the particles of the wear modifier in the liquid dispersion medium, the present composition is prepared by adding and mixing the imide resin as it is (directly) or in a state of being mixed with the liquid dispersion medium. Alternatively, after pre-mixing the imide resin with the liquid dispersion medium, the F particles and the particles of the wear modifier are added as they are (directly) or mixed with the liquid dispersion medium and mixed. Preparation of a composition is preferable from the viewpoint of more uniformly dispersing the F particles. When the present composition further contains a surfactant, other resin material, or inorganic filler, it may be added at the same time as the F particles and the wear modifier particles are pre-dispersed in the liquid dispersion medium, or the F It is preferably added in advance to the liquid dispersion medium before dispersing the particles and the particles of the wear modifier.

Mixing methods for preparing the present composition include, for example, propeller blades, turbine blades, paddle blades, shell-shaped blades and other blades (stirring blades) uniaxially or multiaxially provided with a stirring device, a Henschel mixer, pressurized Stirring by kneader, Banbury mixer or planetary mixer; ball mill, attritor, basket mill, sand mill, sand grinder, dyno mill (bead mill using grinding media such as glass beads or zirconium oxide beads), dispermat, SC mill, spike mill Alternatively, mixing with a dispersing machine that uses media such as an agitator mill; use a dispersing machine that does not use media, such as a high-pressure homogenizer such as a microfluidizer, nanomizer, or ultimizer, an ultrasonic homogenizer, a dissolver, a disper, or a high-speed impeller dispersing machine. mixed.

As a preferred embodiment of the method for producing the present composition, a composition containing F particles, wear modifier particles, an imide resin, and a liquid dispersion medium is kneaded to obtain a kneaded product, and the kneaded product is obtained. An embodiment in which the liquid dispersion medium is further mixed is included.
Kneading can be carried out by the mixing method described above, preferably using a Henschel mixer, a pressure kneader, a Banbury mixer or a planetary mixer, more preferably using a planetary mixer.
The planetary mixer has two stirring blades that rotate and revolve mutually, and has a structure for stirring and kneading the kneaded material in the stirring vessel. Therefore, there is little dead space that the stirring blades do not reach in the stirring vessel, and the load on the blades is reduced, so that the composition can be kneaded to a high degree. In other words, the F particles and the imide resin can be kneaded while suppressing the aggregation of the F particles and wetting the F particles and the wear modifier particles with the liquid dispersion medium, and the F particles and the imide resin can be kneaded while highly interacting with each other. When mixed with a dispersion medium, the present composition having excellent dispersion stability can be easily obtained. In addition, it is easy to adjust the component concentration of the present composition, and it is easy to form a thick sliding coating excellent in surface smoothness and uniformity from the present composition.

The kneaded product is a semi-solid or solid kneaded product, preferably a kneaded paste or dough. The kneaded paste means a hardened product in a fluid and viscous state, and the kneaded powder means a hardened product in a lumpy and clay-like state.
The kneaded paste preferably has a viscosity of 800 to 100000 mPa·s, more preferably 1000 to 10000 mPa·s or more.
The content of the liquid dispersion medium in the dough is preferably 50% by mass or less, more preferably 40% by mass or less. The content of the liquid dispersion medium is preferably 20% by mass or more, more preferably 25% by mass or more.

Further, in this aspect, when the present composition further contains a surfactant, other resin material or inorganic filler, these may be added to the composition, and when the kneaded product and the liquid dispersion medium are mixed, may be added.
That is, the present composition containing other resin materials and inorganic fillers is obtained by kneading and kneading a composition containing F particles, particles of a wear modifier, other resin materials or inorganic fillers, and a liquid dispersion medium. It may also be obtained by obtaining a product and mixing the kneaded product with a mixture containing an imide-based resin and a liquid dispersion medium. In this case, the dispersion stability and long-term storage stability of the present composition are likely to be improved.

The present composition is applied to the surface of a substrate to form a liquid coating, the liquid coating is heated to remove the liquid dispersion medium to form a dry coating, and the dry coating is heated to bake the F polymer. For example, a laminate having on the surface of a base material a sliding coating containing an F polymer, a wear modifier and an imide resin (hereinafter also referred to as "F layer") can be obtained.
From this composition, it has excellent dispersion stability and long-term storage stability, and also has excellent physical properties based on F polymer such as low friction and heat resistance, and has high slidability. A sliding film (F layer) having excellent durability can be formed.
In particular, the composition is useful for forming a sliding member having a base material and an F layer provided on the surface of the base material.

Substrate materials include metals such as iron, copper, nickel, aluminum, titanium, chromium, molybdenum, niobium, and alloys thereof, tetrafluoroethylene-based polymers, polyimides, polyarylates, polysulfones, polyallylsulfones, and polyamides. , polyetheramide, polyphenylene sulfide, polyaryletherketone, polyamideimide, liquid crystalline polyester, and liquid crystalline polyesteramide.
The composition is applied to the surface of a substrate and dried to form an F layer as a sliding coating.

The method of applying the present composition to the surface of the substrate may be any method as long as a stable liquid film (wet film) composed of the present composition is formed on the surface of the substrate. , immersion method, and coating method is preferred. By using the coating method, a liquid coating can be efficiently formed on the surface of the base material with simple equipment.
Coating methods include spray method, roll coating method, spin coating method, gravure coating method, micro gravure coating method, gravure offset method, knife coating method, kiss coating method, bar coating method, die coating method, fountain-meyer bar method, and slot die coating. law.

When drying the liquid coating, the liquid coating is heated at a temperature at which the liquid dispersion medium volatilizes to form a dry coating on the surface of the resin film. The heating temperature for such drying is preferably 100°C to 200°C. Air may be blown in the step of removing the liquid dispersion medium.
During drying, the liquid dispersion medium does not necessarily have to be completely volatilized, and may be volatilized to such an extent that the layer shape after retention is stable and a self-supporting film can be maintained.

When calcining the F polymer, it is preferable to heat the dry film at a temperature equal to or higher than the melting temperature of the F polymer. The temperature for such heating is preferably 380° C. or lower.
Examples of heating methods include a method using an oven, a method using a ventilation drying oven, and a method of irradiating heat rays such as infrared rays. Heating may be performed under normal pressure or under reduced pressure. The heating atmosphere may be any of an oxidizing gas atmosphere (oxygen gas, etc.), a reducing gas atmosphere (hydrogen gas, etc.), and an inert gas atmosphere (helium gas, neon gas, argon gas, nitrogen gas, etc.). .
The heating time is preferably 0.1 to 30 minutes, more preferably 0.5 to 20 minutes.
By heating under the above conditions, the F layer can be suitably formed while maintaining high productivity.

The thickness of the F layer is preferably 1-1000 μm. The thickness of the F layer is more preferably 10 μm or more, more preferably 50 μm or more. The thickness of the F layer is more preferably 500 μm or less.
The peel strength between the F layer and the substrate layer is preferably 10 N/cm or more, more preferably 15 N/cm or more. The peel strength is preferably 100 N/cm or less. By using this composition, the F layer can be easily formed without impairing the physical properties of the F polymer in the F layer.

Here, the outermost surface of the base material may be further surface-treated in order to further improve the adhesiveness with the F layer.
Examples of surface treatment methods include annealing treatment, corona treatment, plasma treatment, ozone treatment, excimer treatment, and silane coupling treatment.
The annealing conditions are preferably a temperature of 120 to 180° C., a pressure of 0.005 to 0.015 MPa, and a time of 30 to 120 minutes.
Gases used for plasma treatment include oxygen gas, nitrogen gas, rare gas (such as argon), hydrogen gas, ammonia gas, and vinyl acetate. These gases may be used singly or in combination of two or more.

Sliding members having a substrate and a sliding coating (F layer) formed from the present composition provided on the surface of the substrate are valves, bearings, bushes, seals, thrust washers, wear rings, and pistons. , slide switches, gears, cams, belt conveyors, food conveying belts, load bearings, rolling bearings and slide bearings in scroll compressors of home or vehicle air conditioners, load bearings, yaws that support the nacelles of wind power generators so that they can turn freely It can be effectively applied to various sliding parts such as bearings.

Although the present liquid composition has been described above, the present invention is not limited to the configurations of the above-described embodiments. For example, the present liquid composition may be added to any other configuration in the configurations of the above-described embodiments, or may be replaced with any configuration that exhibits similar functions.

EXAMPLES The present invention will be described in detail below with reference to Examples, but the present invention is not limited to these.
1. Details of each component [F particles]
Molten F particle 1: containing 97.9 mol%, 0.1 mol% and 2.0 mol% of TFE units, NAH units and PPVE units in this order, and a carbonyl group-containing group having a main chain carbon number of 1 × 10 ⁶ Particles (D50: 2.0 μm) made of polymer (melting temperature: 300 ° C.) with 1000 particles per
Molten F particle 2: Particles (D50: 6 μm) made of a polymer having no functional group (melting temperature: 300° C.) containing 98.0 mol % and 2.0 mol % of TFE units and PPVE units in this order
Non-melting F particles 3: particles made of non-thermally melting PTFE (D50: 6 μm)
[Wear modifier]
Wear modifier 1: spheroidized graphite (D50: 40 μm)
[Imide resin]
Varnish 1: varnish containing water-soluble aromatic polyamideimide resin precursor (PAI1), N-methyl-2-pyrrolidone (NMP) and water [surfactant]
Surfactant 1: polyoxyethylene glycol monoalkyl ether

2. Production Example of Liquid Composition [Example 1-1]
Surfactant 1 and varnish 1 were added to water, mixed, and stirred to prepare a composition. Fused F particles 1 and wear modifier 1 were added to the composition and stirred at 5000 rpm for 10 minutes with a homodisper to obtain molten F particles 1 (40 parts by mass), wear modifier 1 (10 parts by mass) and PAI1. (20 parts by mass), surfactant 1 (2 parts by mass), NMP (25 parts by mass), and water (125 parts by mass) to obtain a liquid composition 1 (viscosity: 2000 mPa·s).

[Example 1-2] to [Example 1-5]
Liquid compositions 2 to 5 were obtained in the same manner as in Example 1-1 except that the types or amounts of F particles, wear modifier and varnish were changed as shown in Table 1. Table 1 shows the viscosity of each liquid composition.

3. Evaluation of Liquid Composition Each liquid composition was evaluated as follows.
3-1. Sedimentation After each liquid composition was allowed to stand for 24 hours, sedimentation of the contents was visually observed, and sedimentation was evaluated according to the following criteria.
[Evaluation criteria]
◯: No sedimentation of particles was observed.
x: Sedimentation of particles is observed.
3-2. Cohesiveness Each liquid composition was passed through a 100-mesh stainless steel mesh, and cohesiveness was evaluated according to the following criteria.
[Evaluation criteria]
◯: Liquid passes through without clogging the mesh.
x: The mesh is clogged and the liquid does not pass.

4. Evaluation of sliding coating 4-1. Appearance A stainless steel plate (width: 30 mm, length: 10 mm, thickness: 1 mm) was immersed in the liquid composition 1 and pulled up at a rate of 1 mm/min to form a wet film on the surface of the stainless steel plate. Then, the stainless plate on which the wet film was formed was dried by heating in an oven at 100° C. for 5 minutes under atmospheric pressure to form a dry film. After that, it was heated in an oven at 350° C. for 10 minutes under atmospheric pressure. As a result, a test piece 1 having a stainless steel plate and a sliding coating (thickness: 100 μm) containing the fused F particles 1, the fired product of PAI 1, and the wear modifier 1 on the surface thereof was obtained.
Test pieces 2-5 were obtained in the same manner as test piece 1, except that liquid composition 1 was changed to liquid compositions 2-5.
The surface of the sliding coating on each test piece was visually observed, and the appearance was evaluated according to the following criteria.
[Evaluation criteria]
◯: No unevenness, peeling, or aggregation was observed in the sliding coating.
Δ: Either unevenness, peeling, or aggregation is observed in part of the sliding coating.
x: Either unevenness, peeling, or agglomeration is observed on the entire sliding coating.

4-2. Adhesion Each test piece was subjected to a 100-square cross-cut test in accordance with JIS K 5600-5-6:1999 (ISO2409:1992), and adhesion was evaluated according to the following criteria.
[Evaluation criteria]
◯: No peeling of the sliding film.
Δ: Peeling of the sliding coating is present at 1 or more and 4 or less locations.
x: Peeling of the sliding coating is present at 5 or more locations.
Each evaluation result is summarized in Table 2 and shown.

[Example 1-6]
Surfactant 1, varnish 1, molten F particles 1 and wear modifier 1 were added to an aqueous dispersion of non-thermally fusible polytetrafluoroethylene particles (D50: 0.3 μm), and the polytetrafluoroethylene Ethylene particles (15 parts by mass), molten F particles 1 (25 parts by mass), wear modifier 1 (10 parts by mass), PAI 1 (20 parts by mass), surfactant 1 (2 parts by mass), NMP (25 parts by mass) parts) and water (125 parts by mass) to obtain a liquid composition 6 (viscosity: 3000 mPa·s). The physical properties (sedimentation, aggregation) of Liquid Composition 6 were equivalent to those of Liquid Composition 1. The physical properties (appearance, adhesion) of the sliding coating formed from liquid composition 6 were also equivalent to those of the sliding coating formed from liquid composition 1.

The liquid composition of the present invention is excellent in dispersion stability and coatability, has excellent physical properties such as low friction and heat resistance, and has high slidability. A film can be formed. Therefore, the liquid composition of the present invention is useful as a constituent material for forming sliding coatings of various sliding members such as bearings.

Claims (15)

The heat-melting tetrafluoroethylene-based polymer comprises particles of a tetrafluoroethylene-based polymer containing particles of a heat-melting tetrafluoroethylene-based polymer, particles of a wear modifier, an imide-based resin, and a liquid dispersion medium. The average particle size of the polymer particles is smaller than the average particle size of the wear modifier particles, and the ratio of the tetrafluoroethylene-based polymer to the total amount of the imide-based resin and the tetrafluoroethylene-based polymer is 50 mass. %, and has a viscosity of 10,000 mPa·s or less, for forming a sliding coating. The liquid composition according to claim 1, wherein the melting temperature of said hot-melt tetrafluoroethylene-based polymer is 200 to 320°C. 3. The liquid composition according to claim 1, wherein the heat-meltable tetrafluoroethylene-based polymer is a tetrafluoroethylene-based polymer having an oxygen-containing polar group. The liquid composition according to any one of claims 1 to 3, wherein the heat-meltable tetrafluoroethylene polymer particles have an average particle size of 0.1 to 25 µm. The liquid composition according to any one of claims 1 to 4, wherein the imide-based resin is an aromatic polyimide, an aromatic polyamideimide, or a precursor thereof. The liquid composition according to any one of claims 1 to 5, wherein the imide-based resin is dissolved in the liquid dispersion medium. The particles of the wear modifier are glass particles, glass fiber pulverized particles, alumina particles, silica particles, talc particles, graphite particles, coke particles, carbon black particles, carbon fiber pulverized particles, bronze (bronze) particles, and molybdenum disulfide particles. , polyimide particles, and polyphenylene sulfide particles, the liquid composition according to any one of claims 1 to 6. The liquid composition according to any one of claims 1 to 7, wherein the liquid dispersion medium is water. 9. The ratio of the average particle size of the particles of the wear modifier to the average particle size of the particles of the hot-melt tetrafluoroethylene polymer is in the range of 2-40. The liquid composition according to . The liquid composition according to any one of claims 1 to 9, wherein the ratio of the mass of the tetrafluoroethylene-based polymer to the total mass of the imide-based resin and the tetrafluoroethylene-based polymer is 80% by mass or less. . The liquid according to any one of claims 1 to 10, wherein the total content of the tetrafluoroethylene-based polymer particles and the imide-based resin is 20% by mass or more with respect to the total mass of the liquid composition. Composition. The content of the particles of the wear modifier is in the range of 0.05 to 1 with respect to the total content of the imide-based resin and the tetrafluoroethylene-based polymer, according to any one of claims 1 to 11. A liquid composition as described. The liquid composition according to any one of claims 1 to 12, further comprising a nonionic surfactant. A sliding member comprising a substrate and a coating formed on the surface of the substrate and formed from the liquid composition according to any one of claims 1 to 13. 15. The sliding member according to claim 14, which is a bearing.