JP2006063279A - In-liquid sliding material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an in-liquid sliding material exhibiting excellent abrasion resistance in a liquid, which easily forms a liquid lubricating membrane even on a surface having a shape where a liquid lubricating membrane is hard to form and which exhibits excellent abrasion resistance even when the liquid lubricating membrane is not formed. <P>SOLUTION: The in-liquid sliding material for forming a sliding member used in the liquid comprises a resin porous body having a communicated hole ratio of at least 30%. The resin porous body contains communicated holes obtained by molding a resin having a pore-forming material incorporated therewith to give a molded body and subsequently extracting the pore-forming material from the molded body using a solvent which dissolves the pore-forming material but not the resin. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a submerged sliding material for forming a sliding member used in a liquid such as oil or water.

A sliding member used in a liquid such as oil or water exhibits lubrication characteristics by holding the liquid on the sliding surface and forming a liquid lubricating film.
Examples of the sliding member used in oil include a metal bearing of an automobile engine part that slides in engine oil. In the bearing, in order to improve sliding characteristics, engine oil is held on the sliding surface, and grooves and dimples are formed on the surface of the bearing that becomes the sliding surface so that an oil film can be easily formed. In addition, sintered metal or the like is often used as a sliding material in oil because the oil film is easily formed on the surface by the same principle.
Resin is mainly used as a sliding material used in water because it is excellent in corrosion resistance and chemical resistance. Such a resin exhibits high sliding properties by blending with water or the like having high affinity with water to retain water on the sliding surface and use it as a lubricant.
Conventionally, as a sliding material that can be used even in water, polytetrafluoroethylene blended with mica or talc and polyimide powder to improve wear resistance compared to conventional resin materials blended with graphite (patent Reference 1).

However, metal sliding materials such as metal bearings and sintered metal, when the product shape is difficult to form an oil film such as flat surfaces, or in the state where the oil film is not formed such as at the start, There is a problem that the metal wears due to strong adhesion and damages the sliding material.
Moreover, since the base material is polytetrafluoroethylene, the sliding material of Patent Document 1 used in water has a problem that it has low strength and cannot be used under high surface pressure conditions. Further, since injection molding cannot be performed, there is a problem that a complicated product shape is expensive because it requires cutting.
Japanese Patent Laid-Open No. 9-71704

  The present invention has been made in order to cope with such problems, and is a liquid sliding material having excellent wear resistance in liquid, and can be easily liquid lubricated even in a surface shape on which a liquid lubricating film is difficult to be formed. An object of the present invention is to provide a submerged sliding material that can form a film and has excellent wear resistance even when a liquid lubricating film is not formed.

The submerged sliding material of the present invention is a submerged sliding material for forming a sliding member used in the liquid, and is made of a porous resin body having a communication porosity of 30% or more. And
The porous resin body is formed by molding a resin containing a pore forming material into a molded body, and then dissolving the pore forming material and using the solvent that does not dissolve the resin from the molded body to the pores. It has the communicating hole obtained by extracting a forming material, It is characterized by the above-mentioned.

  The sliding member formed of the sliding material in liquid has a liquid lubricating film such as an oil film that is easily retained on the surface even if the sliding surface has a planar shape or the like. Can be formed, and its peeling is less likely to occur.

Since the sliding material in liquid of the present invention is composed of a resin porous body having a communication porosity of 30% or more, even if the sliding surface shape is difficult to form a liquid lubricating film such as a planar shape. The liquid lubricating film can be easily formed, and the film can be hardly peeled off and can exhibit excellent sliding characteristics.
Since the resin porous body forming the in-liquid sliding material of the present invention can be used by selecting any resin and filler according to the application and specifications, it has excellent strength, heat resistance, low friction coefficient, Abrasion and the like can also be given. In addition, a sliding member that satisfies the required characteristics can be formed using only the sliding material in liquid without using a reinforcing member such as a back metal.
Further, by using an injection moldable resin, even a sliding member having a complicated shape can be manufactured at low cost.

The submerged sliding material of this invention is a material for forming the submerged sliding member used in arbitrary liquids. Examples of the liquid include oils such as lubricating oil, processing oil, and food oil, water, seawater, various aqueous solutions, chemicals such as hydrochloric acid, sulfuric acid, and nitric acid, and organic solvents such as petroleum benzine, acetone, and ethanol.
The submerged sliding material can be used as a material for an arbitrary submerged sliding member by selecting a resin that forms the resin porous body according to the application and specifications. Examples of the submerged sliding member include a bearing, a gear, a seal ring, and a roller.
Use in advance when the environment where the sliding material in the liquid is used is thin, when the liquid lubrication film is difficult to be formed due to low pressure and high surface pressure, or when the sliding characteristics at the beginning of sliding are important. It is preferable to impregnate the porous resin body with the same liquid as the environment or a liquid that can be mutually dissolved with the liquid. As an impregnation method, any method such as reduced pressure impregnation or pressure impregnation can be used.
Hereinafter, the communication porosity, the resin, the pore forming material, the molding method, and the extraction method that constitute the submerged sliding material of the present invention will be described.

Face-centered cubic lattice and hexagonal close-packed packing are the most densely packed spheres by point contact, and their filling ratio is (volume of sphere ÷ volume of circumscribed cube) ÷ (height of equilateral triangle ÷ base) ÷ (Height of regular tetrahedron ÷ one side) and both are 74%. The porosity defined as (100-filling factor) is 26%.
The above calculation is a case where spheres of the same size are considered. However, when spheres of a plurality of sizes are filled, the filling rate becomes larger than the hexagonal close-packed filling, and the porosity becomes smaller.
Further, when the powdered spherical resin particles are sintered after compression molding, there is no point contact, and the spherical resin particles are deformed and brought into surface contact. For this reason, a filling rate becomes larger than a hexagonal close-packing, and a porosity becomes smaller. For this reason, the porosity of conventional sintered resin moldings is limited to about 20%.

上記、数１において、各符号の意味を以下に示す。
Ｖ；加熱圧縮成形法にて成形された洗浄前成形体の体積
ρ；加熱圧縮成形法にて成形された洗浄前成形体の密度
Ｗ；加熱圧縮成形法にて成形された洗浄前成形体の重量
Ｖ₁；樹脂粉末の体積
ρ₁；樹脂粉末の密度
Ｗ₁；樹脂粉末の重量
Ｖ₂；気孔形成材の体積
ρ₂；気孔形成材の密度
Ｗ₂；気孔形成材の重量
Ｖ₃；洗浄後の多孔体の体積
Ｗ₃；洗浄後の多孔体の重量
Ｖ’₂；洗浄後に多孔体に残存する気孔形成材の体積 The communication porosity in the present invention is the same definition as the above porosity, and refers to the porosity in a state where the pores are continuous. That is, it refers to the ratio of the total volume of pores that are continuous to the resin molded body.
Specifically, the communication porosity was calculated by the method shown in Equation (1) in Equation 1.

In the above Equation 1, the meaning of each symbol is shown below.
V: Volume ρ of the pre-cleaning molded body formed by the heat compression molding method; density W of the pre-cleaning molded body molded by the heat compression molding method; Weight V ₁ ; Volume ρ _{1 of} resin powder; Density W _{1 of} resin powder; Weight V _{2 of} resin powder; Volume ρ _{2 of} pore forming material; Density W _{2 of} pore forming material; Weight V _{3 of} pore forming material; Washing The volume W ₃ of the porous body after; the weight V ′ ₂ of the porous body after cleaning; the volume of the pore forming material remaining in the porous body after cleaning

  In the present invention, a resin porous body having a communication porosity of 30% or more, preferably 30% to 90%, more preferably 30 to 70% is obtained by the production method described below.

The resin porous body that can be used in the present invention is obtained by molding a resin containing a pore-forming material into a molded body, then dissolving the pore-forming material and using a solvent that does not dissolve the resin from the molded body. It is obtained by extracting the forming material. For example, a water-soluble powder B having a melting point Y ° C. higher than X ° C. is blended with a resin A having a molding temperature X ° C., and molded at X ° C. to form a molded body. Is extracted with water to obtain a porous body.
In addition, the manufacturing method of a resin porous body is not restricted to this, The arbitrary methods used as the communicating porosity of 30% or more are employable.

As resin which can be used for this invention, resin powder and pellets, such as a thermoplastic resin, a thermosetting resin, an elastomer, or rubber | gum, can be used. The particle size and shape of the resin powder and pellets are not particularly limited when melt molding because they are kneaded with the pore forming material at the time of melting. In the case of dry blending and compression molding as it is, an average particle diameter of 1 to 500 μm is preferable.
Examples of the thermoplastic resin or thermosetting resin include polyethylene resins such as low density polyethylene, high density polyethylene, and ultrahigh molecular weight polyethylene, modified polyethylene resins, water-crosslinked polyolefin resins, polyamide resins, aromatic polyamide resins, polystyrene resins, Polypropylene resin, silicone resin, urethane resin, polytetrafluoroethylene resin, chlorotrifluoroethylene resin, tetrafluoroethylene / hexafluoropropylene copolymer resin, tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer resin, vinylidene fluoride resin , Ethylene / tetrafluoroethylene copolymer resin, polyacetal resin, polyethylene terephthalate resin, polybutylene terephthalate resin, polyphenylene ether resin, Recarbonate resin, aliphatic polyketone resin, polyvinylpyrrolidone resin, polyoxazoline resin, polyphenylene sulfide resin, polyethersulfone resin, polyetherimide resin, polyamideimide resin, polyetheretherketone resin, thermoplastic polyimide resin, thermosetting Examples thereof include a functional polyimide resin, an epoxy resin, a phenol resin, an unsaturated polyester resin, and a vinyl ester resin. Moreover, the mixture of 2 or more types of materials chosen from the said synthetic resin, ie, a polymer alloy, etc. can be illustrated.

  Examples of the elastomer or rubber include acrylonitrile butadiene rubber, isoprene rubber, styrene rubber, butadiene rubber, nitrile rubber, chloroprene rubber, butyl rubber, acrylic rubber, silicone rubber, fluorine rubber, ethylene propylene rubber, chlorosulfonated polyethylene rubber, chlorinated Examples thereof include vulcanized rubbers such as polyethylene rubber and epichlorohydrin rubber; and thermoplastic elastomers such as polyurethane elastomer, polyester elastomer, polyamide elastomer, polybutadiene elastomer, and soft nylon elastomer.

The pore-forming material is a substance that has a melting point higher than the molding temperature of the resin and can be extracted by being dissolved from the molded body using a solvent that does not dissolve the resin after being blended with the resin to form a molded body. If you can use it.
The pore-forming material is preferably an inorganic salt compound, an organic salt compound, or a mixture thereof, and particularly preferably a water-soluble substance that facilitates the washing and extraction process. Further, an alkaline substance, preferably a weak alkaline substance that can be used as a rust preventive is preferred. Examples of the weak alkali salt include organic alkali metal salts, organic alkaline earth metal salts, inorganic alkali metal salts, inorganic alkaline earth metal salts, and the like. It is preferable to use an organic alkali metal salt or an organic alkaline earth metal salt because even when the unextracted component falls off, it is relatively soft and hardly damages the rolling surface and the sliding surface. In addition, you may use these metal salts 1 type or in mixture of 2 or more types. In addition, it is preferable to use a water-soluble weak alkali salt because inexpensive water can be used as a cleaning solvent, and waste liquid treatment at the time of pore formation is facilitated.
In order to prevent dissolution of the pore forming material during molding, the pore forming material uses a substance having a melting point higher than the molding temperature of the resin used.
Examples of water-soluble organic alkali metal salts that can be suitably used in the present invention include sodium benzoate (melting point: 430 ° C.), sodium acetate (melting point: 320 ° C.) or sodium sebacate (melting point: 340 ° C.), sodium succinate, and stearic acid. Sodium etc. are mentioned. Sodium benzoate, sodium acetate, or sodium sebacate is particularly preferred because of its high melting point, compatibility with various resins, and high water solubility.
Examples of the inorganic alkali metal salt include potassium carbonate, sodium molybdate, potassium molybdate, and sodium tungstate.

The pore forming material manages the average particle size according to the use of the sliding material in liquid.
The ratio of the pore forming material is 30% by volume to 90% by volume, preferably 40% by volume to 90% by volume, with respect to the total amount including other materials such as resin powder, porous body forming material and filler. If the volume is 30% by volume or less, the pores of the porous body are hardly formed into continuous pores.
Moreover, you may mix | blend the filler insoluble in the solvent used for extraction of a pore formation material at the time of a mixing | blending.

For example, glass fiber, pitch-based carbon fiber, PAN-based carbon fiber, aramid fiber, alumina fiber, boron fiber, silicon carbide fiber, for the purpose of improving various mechanical properties by improving the friction and wear characteristics of the sliding material in liquid. Fibers such as silicon nitride fiber, boron nitride fiber, quartz wool, metal fiber, or those knitted into cloth, calcium carbonate, lithium phosphate, lithium carbonate, calcium sulfate, lithium sulfate, talc, silica, clay, mica Minerals such as titanium oxide whisker, potassium titanate whisker, aluminum borate whisker, calcium sulfate whisker, etc., various thermosetting resins such as carbon black, graphite, polyester fiber, polyimide resin and polybenzimidazole resin Etc. can be blended.
For the purpose of improving slidability, amino acid compounds, polyoxybenzoyl polyester resin, polybenzimidazole resin, liquid crystal resin, aramid resin pulp, polytetrafluoroethylene, boron nitride, molybdenum disulfide, tungsten disulfide, etc. Can be blended.

Moreover, for the purpose of improving thermal conductivity, carbon fiber, metal fiber, graphite powder, zinc oxide, aluminum nitride powder or the like may be blended. It is also possible to use a combination of a plurality of the above fillers.
In addition, you may use together the additive which can be widely applied to general synthetic resin with the compounding quantity which does not inhibit the effect of this invention. For example, industrial lubricants such as mold release agents, flame retardants, antistatic agents, weather resistance improvers, antioxidants, colorants, and conductivity-imparting agents may be added as appropriate, and the method of adding these is also particularly limited. Not what

The mixing method of the resin material and the pore forming material is not particularly limited, and a kneading method generally used for mixing the resin such as dry blending and melt kneading can be applied.
Alternatively, a method may be used in which the pore-forming material is dissolved in a liquid solvent to form a transparent solution, and then resin powder is dispersed and mixed in the solution, and then the solvent is removed.
The method of dispersing and mixing is not particularly limited as long as it can be mixed in a liquid, and examples thereof include a ball mill, an ultrasonic disperser, a homogenizer, a juicer mixer, and a Henschel mixer. It is also effective to add a small amount of a surfactant in order to suppress separation of the dispersion. At the time of mixing, the amount of solvent is secured so that the pore forming material is completely dissolved by mixing.
As a method for removing the solvent, methods such as heat evaporation, vacuum evaporation, bubbling with nitrogen gas, dialysis, and freeze-drying can be used. Since the method is easy and the equipment is inexpensive, it is preferable to remove the liquid solvent by heat evaporation.

  Regarding molding of a mixture in which a pore molding material is blended with a resin, any molding method such as compression molding, injection molding, extrusion molding, blow molding, vacuum molding, transfer molding or the like can be adopted depending on the intended sliding member. . Injection molding is preferred because it is easy to form complex shapes. Moreover, in order to improve workability | operativity before shaping | molding, you may process into a pellet, a prepreg, etc.

Extraction of the pore-forming material from the obtained molded body is performed by washing the molded body with a solvent that dissolves the pore-forming material and does not dissolve the resin.
As the solvent, for example, water and alcohol solvents, ester solvents, ketone solvents, and the like can be used as solvents compatible with water. Among these, it is appropriately selected according to the above conditions depending on the type of resin and pore forming material. These solvents may be used alone or in combination of two or more. It is preferable to use water because of its advantages such as easy waste liquid treatment and low cost.
By performing the extraction treatment, the portion filled with the pore forming material is dissolved, and a porous resin body having pores formed in the dissolved portion is obtained.

  In the submerged sliding material of the present invention, since the resin porous body forming the submerged sliding material is produced by the above production method, a polyethylene resin having a molding temperature of 200 ° C. or less as the resin material as listed above, From polyacetal resin, polytetrafluoroethylene resin exceeding 300 ° C., polyether ether ketone resin, etc. can be freely selected in a wide range, and fillers can be blended without the influence of lubricating oil. For example, if the porous resin body is reinforced with fibers, a high-strength sliding material in liquid can be obtained, and if a heat-resistant resin and lubricating oil are used, a sliding material in heat-resistant liquid can be obtained. Further, by using an injection moldable resin, even a complicated shape can be manufactured at low cost.

Example 1
Polyether ether ketone resin powder (150 PF manufactured by Victrex), carbon fiber (MLD100 manufactured by Toray Industries, Inc.) and sodium benzoate powder (reagent manufactured by Wako Pure Chemical Industries, Ltd.) in a volume ratio of 50:10:40 And mixed with a mixer for 5 minutes to obtain a mixed powder. The mixed powder was heat compression molded (380 ° C. × 30 minutes), and then cut into a predetermined molded body (test piece of φ17 mm × φ21 mm × 10 mm). The molded body was washed with warm water at 80 ° C. for 10 hours with an ultrasonic cleaner to elute the sodium benzoate powder. Thereafter, it was dried at 100 ° C. for 8 hours to obtain a porous body having a communication porosity of 38%.

Example 2
Volume ratio of polyphenylene sulfide resin powder (T4AG manufactured by Dainippon Ink Co., Ltd.), carbon fiber (MLD100 manufactured by Toray Industries, Inc.) and sodium benzoate powder (reagent manufactured by Wako Pure Chemical Industries, Ltd.) 50:10:40 Was mixed with a mixer for 5 minutes to obtain a mixed powder. The mixed powder was heat compression molded (330 ° C. × 30 minutes), and then cut into a predetermined molded body (test piece of φ17 mm × φ21 mm × 10 mm). The molded body was washed with warm water at 80 ° C. for 10 hours with an ultrasonic cleaner to elute the sodium benzoate powder. Thereafter, it was dried at 100 ° C. for 8 hours to obtain a porous body having a communication porosity of 38%.

Comparative Example 1
Polyetheretherketone resin powder (150PF manufactured by Victrex) and carbon fiber (MLD100 manufactured by Toray Industries, Inc.) were mixed at a volume ratio of 85:15 with a mixer for 5 minutes, and then heat compression molded (380 ° C. × 30 minutes), and a predetermined test piece (φ17 mm × φ21 mm × 10 mm) was obtained by cutting.

Comparative Example 2
Sintered metal (communication porosity 30%, Cu—Sn system) was cut into predetermined test pieces (φ17 mm × φ21 mm × 10 mm).

Comparative Example 3
Polytetrafluoroethylene resin powder (Mitsui DuPont Fluoro Chemical 7J) and graphite (Nippon Graphite Co., Ltd. ACP) were mixed at a volume ratio of 85:15 for 5 minutes with a mixer, and then heat compression molded (380 And predetermined test pieces (φ17 mm × φ21 mm × 10 mm) were obtained by cutting.

The test pieces prepared in Example 1, Example 2, and Comparative Examples 1 to 3 were subjected to the following oil-in-oil sliding test and underwater sliding test using a ring-on-disk tester. The results are shown in Table 1.
Sliding test in oil:
In order to investigate the friction and wear characteristics in oil, a ring-on-disk test was performed under the following test conditions, and the specific wear amount was measured. Also, the damage of the counterpart material was examined. The case where the counterpart material was not damaged was marked with ◯, and the case where the counterpart material was damaged was marked with X.
Liquid: Automatic transmission oil (Dexylon 2 from Showa Shell Sekiyu KK)
Surface pressure: 5.5 MPa
Speed: 64m / min Time: 5 hours Specimen: φ17mm × φ21mm × 10mm
Mating material: φ33mm × 6mm, SUJ2 (Hardness: HRC62, Surface roughness: Ra = 0.5μm)

Underwater sliding test:
In order to investigate the friction and wear characteristics in water, a ring-on-disk test was performed under the following test conditions, and the specific wear amount was measured. Also, the damage of the counterpart material was examined. The case where the counterpart material was not damaged was marked with ◯, and the case where the counterpart material was damaged was marked with X.
Liquid: Pure water Surface pressure: 0.4 MPa
Speed: 110m / min Time: 50 hours Test piece: φ17mm × φ21mm × 10mm
Mating material: φ33mm × 6mm, SUS304 (Surface roughness: Ra = 0.5μm)

In each example, the specific wear amount is 10 × 10 ^-8 mm ³ / (N · m) or less in oil and 30 × 10 ^-8 mm ³ / (N · m) or less in water, providing excellent wear resistance. It was. Also, no damage to the mating material was seen.

  Since the submerged sliding material of the present invention has excellent wear resistance in the submerged liquid, it is a material for submerged sliding members such as bearings, gears, seal rings, and rollers used in submerged sliding parts. It can be used suitably.

Claims (2)

A sliding material in liquid for forming a sliding member used in liquid,
The in-liquid sliding material is composed of a porous resin body having a communicating porosity of 30% or more.   The porous resin body is formed by molding a resin containing a pore forming material into a molded body, and then dissolving the pore forming material and using the solvent that does not dissolve the resin from the molded body to the pore forming material. The in-liquid sliding material according to claim 1, further comprising a communication hole obtained by extracting the water.