JP2012144591A - Sliding member and sliding part - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sliding member which shows a small friction coefficient and has excellent abrasion resistance in a lubricant-existing service condition, and to provide a sliding part in which the sliding member is disposed at least at a portion of a sliding surface.SOLUTION: The sliding member is characterized as follows. A sliding surface sliding with at least a mating member includes a crosslinked polyrotaxane composed by crosslinking a cyclic molecule in a polyrotaxane including: the cyclic molecule; a linear molecule including the cyclic molecule in a skewer shape; and a blocking group arranged at both terminals of the linear molecule and preventing the elimination of the cyclic molecule. The sliding part is such that the sliding member is disposed at least at a portion of a sliding surface.

Description

  The present invention relates to a sliding member and a sliding component in which the sliding member is provided on at least a part of a sliding surface.

  Many sliding members are used in automobile units having sliding portions and other mechanical units. Conventionally, as a resin-based sliding material effective for reducing friction of a sliding member, for example, Patent Document 1 discloses polytetrafluoroethylene (PTFE) or molybdenum disulfide as a solid lubricant in polyamideimide resin or polyimide resin. The resin composite material which mix | blended is mentioned. However, automobile units such as an engine and a drive system unit are required to further reduce friction loss, and a material exhibiting lower friction characteristics is desired as a sliding member used for these units. In order to reduce energy consumption such as electric power not only in automobile units but also in various machine units having sliding parts such as industrial equipment such as machine tools and household equipment such as air conditioners. There is a need for sliding members that exhibit low friction characteristics.

  In addition to reducing friction loss, it is also important to prevent the occurrence of abnormal noise and vibration caused by friction, such as stick-slip phenomenon and shudder phenomenon, in order to increase the quietness of each unit. It has become. In order to prevent these frictional vibrations, it is effective to reduce the friction coefficient (μ). From such a viewpoint, a material exhibiting low friction characteristics is desired. More specifically, the dependence of the coefficient of friction (μ) on the sliding speed (v), that is, the so-called μ-v characteristic, tends to have a positive gradient (the tendency that μ increases as v increases) to prevent frictional vibration. It has been shown to be effective. The demand for quietness has been increasing in recent years, and the desired vibration-preventing performance cannot be obtained with conventional materials, and materials exhibiting more positive-gradient μ-v characteristics are desired.

  On the other hand, as a new polymer material, for example, as shown in Patent Documents 2 to 7, a polymer material having a movable crosslinked structure by having a cyclic molecule, a linear molecule, and a blocking group has been found. . However, examples of the application include paints and fibers, but application to sliding members for machinery and the like is not found. In a sliding member for a machine, it is desired not only to have low friction characteristics but also to have little wear over a long period of time. However, the existing movable cross-linked polymer material does not have sufficient material strength to resist shearing force when used as a sliding member, and it has not been possible to ensure wear resistance.

Japanese Patent Laid-Open No. 7-097517 International Publication No. 01/083566 Pamphlet JP 2007-099993 A JP 2007-063398 A JP 2007-091938 A JP 2008-001997 A International Publication No. 05/080469 Pamphlet

  An object of the present invention is to provide a sliding member having a small coefficient of friction and good wear resistance under use conditions where a lubricant is present, and the sliding member is provided on at least a part of the sliding surface. It is to provide a sliding part.

  In the present invention, at least a sliding surface that slides with a counterpart member is arranged at both ends of a cyclic molecule, a linear molecule that includes the cyclic molecule in a skewered manner, and the cyclic molecule, It is a sliding member containing the bridge | crosslinking polyrotaxane comprised by the bridge | crosslinking of the said cyclic molecule in the polyrotaxane which has a blocking group which prevents the detachment | leave.

  In the sliding member, the cyclic molecule is preferably at least one selected from the group consisting of α-cyclodextrin, β-cyclodextrin, and γ-cyclodextrin.

In the sliding member, at least one selected from the substituents represented by the following formulas (I-1) to (I-3) in which some or all of the hydroxyl groups of the cyclic molecule are hydroxyl groups. It is preferably substituted by a modifying group.

(Wherein R ₁₁ , R ₁₂ and R ₁₃ are each independently a linear or branched alkyl group having 1 to 12 carbon atoms, or the R _{11 to} R ₁₃ are a hydroxyl group, It may be substituted with at least one selected from the group consisting of a carboxyl group, an acyl group, a phenyl group, a halogen atom, and (R ₁₄ O) ₃ —Si—, and each R ₁₄ independently has 1 carbon atom. ˜3 alkyl or branched alkyl groups, wherein each of R ₁₄ may be the same or different.

  In the sliding member, the cyclic molecule is α-cyclodextrin, and hydrogen atoms of a part or all of the hydroxyl groups of the cyclic molecule are a hydroxypropyl group, a butylcarbamoyl group, an acetyl group, 3- (triethoxy It is preferably substituted with at least one modifying group selected from the group consisting of (silyl) propylcarbamoyl groups.

  In the sliding member, the linear molecule is preferably polyethylene glycol.

  In the sliding member, it is preferable that the crosslinked polyrotaxane does not substantially contain a solvent component.

  In the sliding member, it is preferable that the crosslinking is performed by at least one crosslinking agent selected from the group consisting of an isocyanate compound, a glycidyl ether compound, an alkoxysilane compound, and an imidazole compound.

In the sliding member, the cross-linked polyrotaxane preferably has a Martens hardness HM of 3 N / mm ² or more.

  In the present invention, the sliding member is provided on at least a part of the sliding surface in an intermittent contact state in which a load with a surface pressure of 0.1 MPa or more and a release thereof are repeated. It is a moving part.

  In addition, the present invention provides a sliding bearing, an oil seal, a sliding guide, a guide rail, and a piston for an internal combustion engine, which are used under operating conditions in which the sliding member is provided on at least a part of the sliding surface and a lubricant is present. , Piston ring, cylinder, slider, washer, valve system parts, friction power transmission device (clutch), and sliding that is one of laminated rings and elements used for power transmission belts of belt-type continuously variable transmissions It is a part.

  The sliding member and the sliding component of the present invention exhibit a small coefficient of friction and good wear resistance under use conditions where a lubricant is present.

It is a schematic diagram which shows an example of the molecular structure of the bridge | crosslinking polyrotaxane in the sliding member which concerns on embodiment of this invention. It is a figure which shows the outline of the friction and wear characteristic evaluation method (plate on-ring friction test) in the continuous contact conditions in the Example of this invention. It is a figure which shows the outline of the friction and wear characteristic evaluation method (plate on bar friction test) in the intermittent contact conditions in the Example of this invention. In the Example of this invention, it is a figure which shows the evaluation result of the friction characteristic of various bridge | crosslinking polyrotaxane on the surface pressure of 0.24 MPa conditions in the plate-on-ring friction test in a continuous contact condition. It is a figure which shows the evaluation result of the friction characteristic of the various bridge | crosslinking polyrotaxane on the surface pressure of 0.49 Mpa conditions in the plate-on-ring friction test in a continuous contact condition in the Example of this invention. In the Example of this invention, it is a figure which shows the evaluation result of the friction characteristic of various bridge | crosslinking polyrotaxane on the surface pressure of 0.98 MPa conditions in the plate-on-ring friction test in a continuous contact condition. It is a figure which shows the evaluation result of the load bearing performance of various bridge | crosslinking polyrotaxane in the plate-on-ring friction test in a continuous contact condition in the Example of this invention. It is a figure which shows the result of having measured the roughness shape of the bridge | crosslinking polyrotaxane sliding surface of Film1,4,5 after a series of friction tests using the non-contact three-dimensional surface shape measuring machine in the Example of this invention. It is a figure which shows the evaluation result of the friction characteristic of Film5 and a polyamidoimide type-resin composite material in the intermittent contact conditions evaluated by the plate-on-bar friction test in the Example of this invention. In the Example of this invention, it is a figure which shows the result of having measured the surface roughness shape of Film5 after a plate-on-bar friction test on intermittent contact conditions, and a polyamide-imide-type resin composite material with a non-contact three-dimensional surface shape measuring machine. . In the Example of this invention, it is a figure which shows the result of having measured the surface shape of Film5 after the test on each condition of continuous contact and intermittent contact with the stylus type surface shape measuring instrument. It is a figure which shows the result of having measured the surface shape of Film5 after a plate-on-bar friction test on the intermittent contact conditions in the Example of this invention, and the polyamideimide-type resin composite material with the stylus type surface shape measuring device.

  Embodiments of the present invention will be described below. This embodiment is an example for carrying out the present invention, and the present invention is not limited to this embodiment.

<Cross-linked polyrotaxane>
FIG. 1 shows a schematic molecular structure of the crosslinked polyrotaxane used in the sliding member according to this embodiment. The cross-linked polyrotaxane is a polyrotaxane in which a linear molecule 10 having a linear molecular structure is included in an opening portion of the cyclic molecule 12 having a cyclic molecular structure in a skewered manner. A blocking group 14 is added to both end portions of the linear molecule 10 so that it cannot be detached, and a crosslinking molecule or a crosslinking agent is added to the cyclic molecule 12 portion of the polyrotaxane compound, so that a plurality of polyrotaxane compounds can be crosslinked. 18 is a polymer compound bonded with 18 (hereinafter sometimes abbreviated as a crosslinked polyrotaxane). The cyclic molecule 12 may have a modifying group 16.

  The sliding member according to the embodiment of the present invention includes a cyclic molecule 12, a linear molecule 10 that includes the cyclic molecule 12 in a skewered manner, and both ends of the linear molecule 10. A sliding member using a cross-linked polyrotaxane having a movable cross-linking structure in which a cross-linking point is movable by cross-linking of a cyclic molecule 12 of a polymer component having a polyrotaxane having a basic skeleton having a blocking group 14 that prevents desorption of Yes, at least the sliding surface that slides with the mating member contains the crosslinked polyrotaxane. Since the included cross-linked polyrotaxane has a movable cross-linking structure (hereinafter, may be abbreviated as “cyclic cross-linking”) at least on the sliding surface on which the sliding member according to this embodiment slides with the counterpart member, the same hardness It is considered that elastic deformation and plastic flow are likely to occur compared to other members, the surface is smoothed in a sliding state where a load is applied, and a small friction coefficient is expressed through promotion of formation of a lubricating liquid film by the lubricant. Furthermore, it is considered that even under intermittent contact conditions, it exhibits self-restoration and good wear resistance.

  Unlike materials in which basic skeletal molecules are cross-linked by intermolecular forces or chemical bonds, such as conventional polymer and rubber-based sliding materials such as resins and rubbers, the molecular structure of the It is considered that the degree of freedom of deformation increases and self-restorability can be imparted to ensure good wear resistance. Also, under sliding conditions in which local high surface pressure is generated, uniform surface pressure distribution, that is, maximum surface pressure can be reduced due to the ease of elastic deformation, which is considered to be a factor in obtaining good wear resistance. It is done.

[Polyrotaxane or Polyrotaxane molecule]
In the present embodiment, “polyrotaxane” or “polyrotaxane molecule” refers to a pseudo-molecule in which the opening of the cyclic molecule 12 is skewered by the linear molecule 10, and the cyclic molecule 12 includes the linear molecule 10. A molecule in which blocking groups 14 are arranged at both ends of the polyrotaxane (both ends of the linear molecule 10) so that the cyclic molecule 12 is not detached.

[Cyclic molecules in polyrotaxane]
The cyclic molecule in the polyrotaxane is not particularly limited as long as it is included in the linear molecule as described above and exhibits a pulley effect, and various cyclic substances can be exemplified. Many cyclic molecules have a hydroxyl group. In addition, it is sufficient that the cyclic molecule is substantially cyclic, and it is not necessarily required to be completely closed like “C” shape.

  Examples of cyclic molecules include various cyclodextrins (for example, α-cyclodextrin, β-cyclodextrin, γ-cyclodextrin, dimethylcyclodextrin and glucosylcyclodextrin, derivatives or modified products thereof), crown ethers, benzo Examples include crowns, dibenzocrowns, and dicyclohexanocrowns, and derivatives or modified products thereof. Of the various cyclic molecules, α-cyclodextrin, β-cyclodextrin, and γ-cyclodextrin are particularly preferable from the viewpoints that many hydroxyl groups exist and modification of the hydroxyl groups is easy. From the viewpoint of adhesion and the like, α-cyclodextrin is more preferable.

  The above-mentioned cyclic molecules such as cyclodextrin can be used alone or in combination of two or more.

  In the present embodiment, the number (inclusion amount) of the cyclic molecule included in the linear molecule is 0.06 to 0 when the maximum inclusion amount is 1 when the cyclic molecule is cyclodextrin. .61 is preferred. If it is less than 0.06, the pulley effect may not be exhibited, and if it exceeds 0.61, cyclodextrin, which is a cyclic molecule, may be arranged too densely and the mobility of cyclodextrin may be lowered.

[Modifying group of cyclic molecule in polyrotaxane]
In the polyrotaxane of the present embodiment, at least some of the hydroxyl groups of the cyclodextrin as a cyclic molecule are selected from substituents represented by the following formulas (I-1) to (I-3). It may be substituted by one type of modifying group.

(Wherein R ₁₁ , R ₁₂ and R ₁₃ are each independently a linear or branched alkyl group having 1 to 12 carbon atoms, or the R _{11 to} R ₁₃ are a hydroxyl group, It may be substituted with at least one selected from the group consisting of a carboxyl group, an acyl group, a phenyl group, a halogen atom, and (R ₁₄ O) ₃ —Si—, and each R ₁₄ independently has 1 carbon atom. ˜3 alkyl or branched alkyl groups, wherein each of R ₁₄ may be the same or different.

  Specific examples of the substituents represented by the above formulas (I-1) to (I-3) include alkyl groups such as a methyl group, an ethyl group, an isopropyl group, a propyl group, and a hexyl group; a hydroxypropyl group Substituted alkyl groups such as acetyl groups, propionyl groups, hexanoyl groups, etc .; alkyl carbamoyl groups such as ethyl carbamoyl group, propyl carbamoyl group, isopropyl carbamoyl group, butyl carbamoyl group, hexyl carbamoyl group; Groups having an alkoxysilyl group such as ethoxymethylsilyl group, trimethoxysilyl group, dimethoxymethylsilyl group; groups having an alkylsilyl group such as trimethylsilyl group, dimethylethylsilyl group, dimethylisopropylsilyl group, etc. It is not limited to.

  As an application target of the sliding member according to the present embodiment, a machine part that is slid using an oil-based or water-based lubricant is suitable. In order to make it easy to form a lubricant film, it is desirable that the sliding member has a high lipophilicity when applied to a sliding portion of an automobile engine or transmission in which a hydrocarbon-based lubricating oil is used. As a member to be applied to sliding conditions in which such a lubricant is used, a hydroxypropyl group, a butylcarbamoyl group, and a terminal of a cyclic molecule in a polyrotaxane are higher in lipophilicity with a lubricant than those having a hydroxyl group. It is preferably modified with at least one selected from the group consisting of an acetyl group and a 3- (triethoxysilyl) propylcarbamoyl group. By ensuring the affinity with the lubricant, it is possible to further impart oil retention without inhibiting the formation of the lubricating liquid film, and to ensure stable low friction characteristics and wear resistance.

  In the present embodiment, the degree of modification of a cyclic molecule with a chemical modification group is preferably 0.02 or more, assuming that the maximum number of hydroxyl groups of the cyclic molecule that can be modified is 1. If it is less than 0.02, the solubility in an organic solvent may not be sufficient, and an insoluble material may be generated. In addition, the maximum number that the hydroxyl groups of cyclodextrin can be modified is, in other words, the total number of hydroxyl groups that cyclodextrin had before modification. Further, the degree of modification is, in other words, the ratio of the number of modified hydroxyl groups to the total number of hydroxyl groups.

  In addition, when it has many cyclodextrins, in all the cyclodextrins to have, the hydroxyl group of all or one part does not need to be modified by the modification group.

[Linear molecules in polyrotaxane]
The linear molecule may be substantially linear, and may have a branched chain as long as the cyclic molecule as a rotor can be rotated and can be included so as to exert a pulley effect. Further, although it is affected by the size of the cyclic molecule, its length is not particularly limited as long as the cyclic molecule can exert a pulley effect.

  In addition, as a linear molecule, what has a reactive group in the both ends is preferable, and this enables it to react with a blocking group easily. Such a reactive group can be appropriately changed according to the type of blocking group employed, and examples thereof include a hydroxyl group, an amino group, a carboxyl group, and a thiol group.

  Such a linear molecule is not particularly limited, and is a polyester having a polyalkylene, polycaprolactone, or the like, a polyether such as polyethylene glycol, a polyamide, a polyacryl, or a linear chain having a benzene ring. And the like. In particular, polyethylene glycol is preferable from the viewpoint of easy inclusion in a cyclic molecule.

  Further, the molecular weight of the linear molecule is preferably 1,000 to 1,000,000. If the molecular weight of the linear molecule is less than 1,000, the pulley effect due to the cyclic molecule cannot be obtained sufficiently, the amount of elastic deformation of the member is reduced, and the shape self-restoration and effective wear resistance can be obtained. It may disappear. When the molecular weight exceeds 1,000,000, the viscosity of the raw material becomes too high, and it becomes difficult to perform uniform stirring at the time of synthesis, making it difficult to obtain a stable compound.

[Blocking group in polyrotaxane]
As the blocking group, any group can be used as long as it is arranged at both ends of the linear molecule and can maintain a state in which the cyclic molecule is pierced by the linear molecule. Absent. Examples of such a group include a group having “bulkyness”. Here, the “group” means various groups including a molecular group and a polymer group.

  Examples of the group having “bulkyness” include a spherical shape and a side wall-shaped group.

  Specific examples of such “bulky” blocking groups include adamantane groups, dinitrophenyl groups, cyclodextrins, trityl groups, fluoresceins and pyrenes, substituted benzenes, and optionally substituted. And polynuclear aromatics. Among these, an adamantane group is preferable from the viewpoints of the safety of the compound and the non-coloring property.

[Crosslinking molecules and crosslinking agents that bind polyrotaxane]
It is preferable that the polyrotaxane cyclic molecule and another polyrotaxane or polymer are bonded by a chemical bond with a crosslinking agent. Although it does not specifically limit as a crosslinking agent, What is necessary is just a crosslinking agent which can react with functional groups, such as a hydroxyl group on a cyclic molecule, an amino group, and a carboxyl group. Examples thereof include alkoxysilanes, isocyanates, oxetanes, oxiranes, acid anhydrides, imidazoles and the like. Specifically, hexamethylene diisocyanate, hexamethylene diisocyanate biuret type, isocyanurate type, adduct type, tolylene-2, 4-diisocyanate, isophorone diisocyanate, cyanuric chloride, trimesoyl chloride, terephthaloyl chloride, epichlorohydride Phosphorus, dibromobenzene, glutaraldehyde, phenylene diisocyanate, divinyl sulfone, 1,1,1′-carbonyldiimidazole, and the like can be used, and these can be used alone or in combination of two or more. Moreover, you may bridge | crosslink the group which has the said alkoxy silyl group which is a modification group of a cyclic molecule. Among these, from the viewpoint of compatibility with the solvent and polyrotaxane at the time of material preparation, crosslinking is performed with at least one crosslinking agent selected from the group of isocyanate compounds, glycidyl ether compounds, alkoxysilane compounds, and imidazole compounds. It is preferable that

[Method for producing crosslinked polyrotaxane]
Here, the crosslinked polyrotaxane used in the present embodiment can be obtained by, for example, processing according to the following steps.
(1) A cyclic molecule and a linear molecule are mixed, and the opening of the cyclic molecule is inserted in a skewered manner with the linear molecule, and the cyclic molecule is included in the linear molecule. Both ends of the polyrotaxane (both ends of the linear molecule) are blocked with a blocking group to form a molecular structure in which the cyclic molecule is not detached from the skewered state. (3) If necessary, the cyclic molecule of the obtained polyrotaxane (4) The obtained polyrotaxane is crosslinked to obtain a crosslinked polyrotaxane.

  The steps (1) to (4) may be performed according to the method described in, for example, International Publication No. 05/080469.

  In the step (4), polyrotaxane, components other than polyrotaxane, a crosslinking agent, and the like may be dissolved in a solvent in advance. Examples of the solvent include, but are not limited to, organic solvents such as toluene, xylene, butyl acetate, methyl ethyl ketone, cyclohexanone, dimethyl sulfoxide, dimethylformaldehyde, and dimethylacetamide. Further, in the crosslinking step, it may be performed under conditions such as normal pressure, reduced pressure, room temperature, and heating, although it varies depending on the solvent and the crosslinking agent used.

[Containing components other than polyrotaxane]
As a sliding member using the crosslinked polyrotaxane of the present embodiment, a resin component, a solid lubricant, an additive, a pigment, a catalyst, a mold release, a filler, a solvent, and the like are optionally added to the crosslinked polyrotaxane. A combination of the above is blended according to a conventional method and mixed to form, for example, a molded body or the like. Two or more resin components may be mixed and used.

  Further, the resin component may be a homopolymer or a copolymer. In the case of the copolymer, it may be composed of two or more monomers, and may be any of a block copolymer, an alternating copolymer, a random copolymer, or a graft copolymer.

  Specific examples of the resin component include, for example, polystyrene, polyvinyl alcohol, acrylonitrile-butadiene-styrene copolymer (ABS resin), polyethylene, polypropylene, polyvinyl chloride, vinyl acetate resin, polyamide (nylon), polyamideimide, polyimide, Examples include polyacetal, polycarbonate, polyethylene terephthalate, poly (meth) acrylic acid, silicon resin, fluorine resin, phenol resin, epoxy resin, polyurethane, unsaturated polyester, furan resin, aniline resin, and derivatives thereof.

[Crosslinked polyrotaxane containing no solvent component]
By making the crosslinked polyrotaxane substantially free of a solvent component, the Martens hardness described later can be 3 N / mm ² or more.

In the present embodiment, the crosslinked polyrotaxane “substantially free of solvent component” does not contain a high-molecular polyethylene glycol component that does not easily volatilize as a solvent, and is at least 6.7 × 10 ⁻³ MPa in the final drying treatment. A drying treatment is performed at 80 ° C. or higher for 2 hours under the following reduced pressure conditions. As described above, by performing the drying treatment for 2 hours, the weight change is hardly recognized (0.5 wt% or less) even when the drying treatment is performed for 1 h under the same reduced pressure heating condition.

That is, the “substantially solvent-free” crosslinked polyrotaxane in the sliding member according to the present embodiment is a case where heating is performed at 80 ° C. under a reduced pressure condition of 7 × 10 ⁻³ MPa or less and a drying treatment is performed for 1 h. It is a crosslinked polyrotaxane having a weight change of 0.5 wt% or less.

[Effective hardness]
The crosslinked polyrotaxane in the present embodiment is a compound having a Martens hardness (HM) measured in accordance with ISO14577 of 3 N / mm ² or more from the viewpoint of ensuring wear resistance when applied to a sliding member. Preferably, it is a compound having 10 N / mm ² or more, and particularly preferably a compound having 80 N / mm ² or more. By adjusting the degree of cross-linking of the cross-linked polyrotaxane so that the Martens hardness (HM) is 3 N / mm ² or more, sufficient material strength can be imparted to the shearing force caused by friction, and good wear resistance is achieved. It can be secured.

<Lubricant used in sliding parts for machines to which sliding members are applied>
Examples of the lubricant used in combination with the sliding member according to the present embodiment include engine oils, transmission oils, machining lubricating oils and hydraulic oils mainly composed of paraffinic and olefinic hydrocarbon oils. Can be mentioned. Furthermore, oil for jet engines mainly composed of ester oils or bearing oils for precision machinery parts, fluid for brake systems mainly composed of glycol oils, refrigeration oils and vacuum pump oils mainly composed of ether oils, silicones And high-temperature lubricating oil mainly composed of a base oil or a fluorine-based oil. Further, there may be mentioned electronic component contact lubricants mainly composed of alcohol solvents such as water-based and emulsion-based lubricants for cutting and processing lubricants.

<Sliding parts>
The sliding member according to the present embodiment is suitably applied to a machine part that is slid using an oil-based or water-based lubricant. For example, the sliding member according to the present embodiment is provided on a part of the sliding surface, a sliding bearing used under use conditions where a lubricant is present, an oil seal, a sliding guide, a guide rail, a piston for an internal combustion engine, Examples thereof include sliding parts such as piston rings, cylinders, sliders, washers, valve system parts, frictional power transmission devices (clutches), and laminated rings and elements used for power transmission belts of belt-type continuously variable transmissions.

  In the sliding component according to the present embodiment, the sliding member is at least a part of a sliding surface in an intermittent contact state in which a load with a surface pressure of 0.1 MPa or more is repeatedly applied and released. It is a sliding part provided in. In such an intermittent contact state, the sliding component according to the present embodiment exhibits a small coefficient of friction and particularly good wear resistance.

  The sliding member and the sliding component according to the present embodiment exhibit a small friction coefficient and good wear resistance under use conditions where a lubricant is present, thereby reducing the friction loss of the mechanical unit or preventing stick slip. Etc. are possible.

  Hereinafter, although an example and a comparative example are given and the present invention is explained more concretely in detail, the present invention is not limited to the following examples.

<Production of polyrotaxane>
In the polyrotaxane in which polyethylene glycol having a linear molecular structure is clasped into the opening of an α-cyclodextrin molecule having a cyclic molecular structure, polyethylene is used so that the α-cyclodextrin cannot be detached from the polyethylene glycol molecule. A polyrotaxane compound in which blocking groups were added to both ends of the glycol molecule was produced. A polymer compound (crosslinked polyrotaxane) in which a plurality of polyrotaxane compounds were bonded was prepared by adding a crosslinking molecule or a crosslinking agent to the cyclic molecular portion of the polyrotaxane compound.

  Α-cyclodextrin or a modified polyrotaxane in which hydrogen atoms of a part or all of hydroxyl groups of α-cyclodextrin are substituted with other modifying groups as a cyclic molecule, and polyethylene glycol having a weight average molecular weight of 35,000 as a linear molecule. Using. An adamantyl group was added as a blocking group.

  For the cross-linking molecule, a plurality of types of compounds were prepared by combining glycidyl ether, alkoxysilane, isocyanate or polyisocyanate and isocyanate alkoxysilane compounds. In addition, in the compound production process, water or polyethylene glycol was used as a reaction solvent, and a crosslinked polyrotaxane in which a solvent component was contained in the finally obtained compound body was also produced.

About the used polyrotaxane, it produced with the following method.
[Synthesis Example 1]
An adamantane polyrotaxane composed of a linear molecular polyethylene glycol (weight average molecular weight 35,000) and a blocking group adamantyl group was prepared in the same manner as described in International Publication No. 05/080469. .

<Preparation of PEG-carboxylic acid by TEMPO oxidation of PEG>
10 g of PEG (weight average molecular weight 35,000), 100 mg of TEMPO (2,2,6,6-tetramethyl-1-piperidinyloxy radical), and 1 g of sodium bromide were dissolved in 100 mL of water. 5 mL of a commercially available sodium hypochlorite aqueous solution (effective chlorine concentration: about 5%) was added to the resulting solution, and the mixture was allowed to react at room temperature (about 22 ° C.) with stirring. As the reaction progressed, the pH of the system rapidly decreased immediately after the addition, but was prepared by adding 1N NaOH so as to keep the pH: 10-11 as much as possible. The decrease in pH disappeared within about 3 minutes, but the mixture was further stirred for 10 minutes. Ethanol was added in a range up to 5 mL to terminate the reaction. Extraction with 50 mL of methylene chloride was repeated three times to extract components other than inorganic salts, and then methylene chloride was distilled off with an evaporator. After dissolving in 250 mL of warm ethanol, the PEG-carboxylic acid, that is, the one in which both ends of PEG were replaced with carboxylic acid (—COOH) was deposited overnight in a freezer at −4 ° C. The precipitated PEG-carboxylic acid was collected by centrifugation. This warm ethanol dissolution-precipitation-centrifugation cycle was repeated several times, and finally dried by vacuum drying to obtain PEG-carboxylic acid. The yield was 95% or more, and the carboxylation rate was 95% or more.

<Preparation of inclusion complex using PEG-carboxylic acid and α-CD>
After dissolving 3 g of PEG-carboxylic acid prepared above and 12 g of α-CD in 50 mL of warm water of 70 ° C. separately prepared, both were mixed, and then allowed to stand overnight in a refrigerator (4 ° C.). The inclusion complex deposited in the form of cream was lyophilized and recovered. The yield was 90% or more (yield: about 14 g).

<Sealing of inclusion complex using adamantaneamine and BOP reagent reaction system>
At room temperature (about 22 ° C.), 0.13 g of adamantaneamine was dissolved in 50 mL of dimethylformamide (DMF), added to 14 g of the inclusion complex obtained above, and then quickly and well mixed. Subsequently, 0.38 g of BOP reagent (benzotriazol-1-yl-oxy-tris (dimethylamino) phosphonium hexafluorophosphate) dissolved in 25 mL of DMF was added and shaken well in the same manner. Further, 0.14 mL of diisopropylethylamine was added to a solution of 25 mL of DMF, and the mixture was shaken well in the same manner. The resulting mixture was left in the refrigerator overnight. Thereafter, 100 mL of a DMF / methanol = 1: 1 mixed solution was added and mixed well, centrifuged, and the supernatant was discarded. This washing with the DMF / methanol mixed solution was repeated twice, and further washing with 100 mL of methanol was repeated twice by the same centrifugation. The obtained precipitate was vacuum-dried and then dissolved in 50 mL of dimethyl sulfoxide (DMSO), and the obtained transparent solution was dropped into 700 mL of water to precipitate polyrotaxane. The precipitated polyrotaxane was collected by centrifugation and vacuum-dried or freeze-dried. This DMSO dissolution-precipitation-recovery-drying cycle in water was repeated twice to finally obtain a purified polyrotaxane. The yield based on the added inclusion complex was about 68% (the yield from 14 g of the inclusion complex was 9.6 g).

^{By 1} H-NMR analysis (manufactured by JOEL, JNM-AL400), it was confirmed that about 99 α-cyclodextrins were included in the polyrotaxane. On the other hand, when α-cyclodextrin is densely packed in the used polyethylene glycol, it can be calculated by calculation that the maximum inclusion amount is 398. From this calculated value and the measured value of NMR, it was found that the inclusion rate of α-cyclodextrin in the obtained polyrotaxane was 0.25. Moreover, the weight average molecular weight Mw was 12,000 by GPC analysis (the Tosoh make, TOSOH HLC-8220GPC). The prepared polyrotaxane is designated as PR-1.

[Synthesis Example 2]
A compound obtained by further hydroxypropylating the polyrotaxane of Synthesis Example 1 was prepared as follows in the same manner as described in International Publication No. 05/080469.

3.0 g of the polyrotaxane obtained above was dissolved in 40 mL of 1N NaOH aqueous solution, and 25 g of a large excess of propylene oxide was added. The mixture was stirred at room temperature (about 22 ° C.) for 24 hours and then neutralized with hydrochloric acid. This solution was dialyzed in a dialysis tube (fraction molecular weight: 12,000) for 48 hours under running tap water. Further, dialysis was performed twice in 500 mL purified water for 3 hours. Lyophilization was performed and the yield of the product obtained was 3.1 g. The weight average molecular weight Mw was 150,000 by GPC analysis, and the hydroxypropylation rate was 48% by ¹ H-NMR analysis. The prepared modified polyrotaxane is designated as PR-2.

[Synthesis Example 3]
10 g of the polyrotaxane prepared in Synthesis Example 2 is dissolved in 100 mL of dimethylacetamide, and while stirring, 4.3 g of n-butyl isocyanate (manufactured by Tokyo Chemical Industry), 1.2 g of 3- (triethoxysilyl) propyl isocyanate (manufactured by Tokyo Chemical Industry) Was slowly added dropwise and allowed to react for 6 hours. The reaction solution was poured into hexane, the precipitate was collected, washed several times with hexane, hexane was distilled off, and the residue was dissolved in 30 mL of methanol. ^{According to 1} H-NMR analysis, the modification rate of the butylcarbamoyl group was 45%, the modification rate of the 3- (triethoxysilyl) propylcarbamoyl group was 5%, and the weight average molecular weight Mw was 210,000 according to GPC analysis. The molecular weight distribution Mw / Mn was 2.1. The obtained modified polyrotaxane solution (about 25 wt% methanol solution) is designated as PR-3.

[Synthesis Example 4]
3 g of polyrotaxane (PR-2) produced in Synthesis Example 2 was dissolved in 30 mL of dimethylacetamide, and 3.0 mL of triethylamine and 1.4 mL of acetic anhydride were added dropwise with stirring to react for 5 hours. Thereafter, the solution was dropped into 360 mL of hexane, and the precipitate was dialyzed with a dialysis tube (fraction molecular weight 12,000) for 24 hours under running tap water. Furthermore, it was performed twice for 3 hours in purified water. The product obtained by lyophilization was subjected to GPC analysis to have a weight average molecular weight Mw of 160,000 and a molecular weight distribution Mw / Mn of 1.3. ^{From 1} H-NMR, the acetylation rate relative to the total number of hydroxyl groups was 48%. The obtained modified polyrotaxane is referred to as PR-4.

[Synthesis Example 5]
A polyrotaxane was produced in the same manner as in Synthesis Example 4, except that 1.2 mL of triethylamine and 0.56 mL of acetic anhydride were used instead of 3.0 mL of triethylamine and 1.4 mL of acetic anhydride used in Synthesis Example 4. According to GPC analysis, the obtained product had a weight average molecular weight Mw of 140,000 and a molecular weight distribution Mw / Mn of 1.3. ^{From 1} H-NMR, the acetylation rate relative to the total number of hydroxyl groups was 20%. The obtained modified polyrotaxane is referred to as PR-5.

[Synthesis Example 6]
10 g of the polyrotaxane (PR-1) produced in Synthesis Example 1 was dissolved in 200 mL of a 4% lithium chloride solution of dehydrated dimethylformamide (DMF). After dissolving 1.7 g of 4-dimethylaminopyridine (DMAP) in the obtained solution, 4.3 mL of triethylamine and 2.6 mL of acetic anhydride were added in order, and the mixture was reacted at room temperature (about 22 ° C.) for 5 hours. The reaction solution was dialyzed in a dialysis tube (fraction molecular weight 12,000) for 24 hours under running tap water. Furthermore, it was performed twice for 3 hours in purified water. After filtration, lyophilization was performed to obtain a product in which the —OH group of α-CD was partially substituted with an acetyl group. ^{From 1} H-NMR, the acetylation rate relative to the total number of hydroxyl groups was 20%. By GPC analysis, the weight average molecular weight Mw was 100,000 and the molecular weight distribution Mw / Mn was 1.4. The obtained modified polyrotaxane is referred to as PR-6.

<Production of crosslinked polyrotaxane>
[Example 1]
1.0 g of PR-1 of Synthesis Example 1 was dissolved in 4 mL of 1.0 N NaOH aqueous solution, and 0.12 mL of 1,4-butanediol diglycidyl ether (manufactured by Tokyo Chemical Industry) was added and stirred uniformly. This solution is poured into a 50 × 50 × 0.5 mm thick mold, reacted at room temperature (about 22 ° C.) for 20 hours, then taken out of the mold, solvent-replaced with pure water until neutral, and sample water -B was obtained.

[Example 2]
1.2 g of PR-2 of Synthesis Example 2 was dissolved in 3 mL of a 1.0 N NaOH aqueous solution, and 0.12 mL of 1,4-butanediol diglycidyl ether (manufactured by Tokyo Chemical Industry) was added and stirred uniformly. This solution was poured into a 70 × 70 × 1.0 mm thick mold and allowed to react at room temperature (about 22 ° C.) for 20 hours, and then the gel was taken out of the mold and replaced with pure water until neutral. Subsequently, the gel was immersed in polyethylene glycol (PEG) (weight average molecular weight 300) to change the solvent from water to PEG. This operation was performed three times to obtain sample PEG-B in which water was replaced with PEG.

  In addition, using various polyrotaxanes prepared in Synthesis Examples, an attempt was made to produce a film having a crosslinked polyrotaxane and containing no solvent.

[Comparative Example 1]
The gel of Example 1 (Water-B) was allowed to stand at room temperature (about 22 ° C.) for 2 days and then vacuum-dried at 60 ° C. for 3 hours to produce a sample Water-C film. As a result, a sample suitable as a sliding material could not be produced.

[Example 3]
The PR-3 methanol solution of Synthesis Example 3 was poured into a test plate (iron mold) having a diameter of 40 mm and a depth of 2 mm and left to stand at room temperature (about 22 ° C.) for 1 day. The film was dried by heating at 80 ° C. for 2 hours under reduced pressure conditions of 70 ° C. for 1 h and about 6.7 × 10 ⁻³ MPa to obtain a smooth thin film on the mold. Let the obtained sample be Film1.

[Example 4]
After dissolving 0.8 g of PR-4 prepared in Synthesis Example 4 in a mixed solvent of 2.0 mL of methyl ethyl ketone and 0.8 mL of dimethyl sulfoxide, 0.21 g of hexamethylene diisocyanate (manufactured by Tokyo Chemical Industry) was added and stirred uniformly. Pour into a test plate (iron mold) with a diameter of 40 mm and a depth of 2 mm and leave it at room temperature (about 22 ° C.) for 4 h, then continue at normal pressure 50 ° C. for 1 h, normal pressure 80 ° C. for 1 h, about 6.7 × 10 ⁻³ Heat drying at 80 ° C. for 2 h under a reduced pressure condition of MPa to obtain a smooth thin film on the mold. The obtained sample is referred to as Film2.

[Example 5]
0.88 g of PR-4 produced in Synthesis Example 4 was dissolved in 5.0 mL of dimethylformaldehyde, and 8.8 μL of dibutyltin dilaurate (IV) was added and stirred well. After adding 0.074 g of Duranate TPA-100 (isocyanate type curing agent, manufactured by Asahi Kasei) and 0.044 g of 3-isocyanatopropyltriethoxysilane (KBE-9007, manufactured by Shin-Etsu Chemical Co., Ltd.) and stirring, diameter 40 mm, depth 2 mm And was allowed to stand at 60 ° C. for 2 hours for crosslinking. Thereafter, the solvent was removed by heating and drying at 80 ° C. for 2 hours under a reduced pressure condition of about 6.7 × 10 ⁻³ MPa. The obtained sample is referred to as Film4.

[Example 6]
1.0 g of PR-5 prepared in Synthesis Example 5 was dissolved in 5.6 mL of dimethylformaldehyde, and 5.0 μL of dibutyltin dilaurate (IV) was added and stirred well. After adding 0.29 g of Duranate TPA-100 (isocyanate type curing agent, manufactured by Asahi Kasei) and 0.15 g of 3-isocyanatopropyltriethoxysilane (KBE-9007, manufactured by Shin-Etsu Chemical Co., Ltd.) and stirring, diameter 40 mm, depth 2 mm Then, the mixture was allowed to stand at 40 ° C. for 6 hours and cross-linked, and then dried by heating at 80 ° C. for 2 hours under reduced pressure of about 6.7 × 10 ⁻³ MPa to remove the solvent. The obtained sample is named Film5.

  The composition of the produced crosslinked polyrotaxane is shown in Table 1. (1) and (2) are crosslinked polyrotaxanes of a type containing a solvent using glycidyl ether as a crosslinking molecule. (1) uses α-cyclodextrin in which a cyclic molecule is not chemically modified. (2) is a crosslinked polyrotaxane containing a linear polyethylene glycol having a weight average molecular weight of 300 as a solvent using a modified cyclodextrin modified with a hydroxypropyl group as a cyclic molecule. (3) was an attempt to eliminate the solvent based on (1), but cracking occurred during curing, and a sample suitable for the sliding member could not be produced. (4) is a modified cyclodextrin in which a part of the hydroxyl groups of α-cyclodextrin is substituted with a hydroxypropyl group, a butylcarbamoyl group and an alkoxysilane, and the alkoxysilane is crosslinked. (5) is a modified cyclodextrin. As a dextrin, α-cyclodextrin is substituted with a hydroxypropyl group and an acetyl group, and is crosslinked using isocyanate as a crosslinking agent. (6) A hydrogen atom of a part of hydroxyl groups is substituted with a hydroxypropyl group and an acetyl group and crosslinked using a polyisocyanate and an isocyanate alkoxysilane compound as a crosslinking agent. Department of water A hydrogen atom of the group is substituted only with an acetyl group, it is obtained by crosslinking with polyisocyanates and isocyanate alkoxysilane compound as the crosslinking agent, a solvent-free type crosslinked polyrotaxane.

  In Table 1, as a physical property value of the prototype crosslinked polyrotaxane, Martens hardness measured according to ISO14577 using an ultra micro hardness tester (Fischer Instruments, FISCHERSCOPE (registered trademark) HM2000). (Martenshardness, HM) and indentation Young's modulus are noted. Plate test pieces in which these prototype crosslinked polyrotaxanes were bonded to a SUS plate substrate were prepared and subjected to a friction test described later.

[Comparative Example 2]
For comparison, Exgel Corporation's Hypergel Sheet 3030 was used as a urethane gel for evaluation of frictional wear characteristics described below. The hardness of this urethane gel is 13 in durometer A hardness. When this value is estimated from the relationship between durometer A hardness and Martens hardness measured for other materials, the Martens hardness is about 1.9 N / mm ^2. Become.

[Comparative Example 3]
In addition, a plate test piece in which a composite resin material used as a low friction coating material for an engine piston skirt was coated on an aluminum plate with a thickness of 10 μm was also prepared and subjected to a frictional wear test. This composite resin material is obtained by dispersing molybdenum disulfide powder as a solid lubricant in a polyamideimide resin. The Martens hardness HM measured using a microhardness tester is 284 N / mm ² and the indentation Young's modulus is 6.4 GPa.

<Method for evaluating friction and wear characteristics>
[Evaluation under continuous contact conditions]
By the plate-on-ring friction test shown in FIG. 2, the friction and wear characteristics under continuous contact sliding conditions were evaluated for (1) Water-B and (2) PEG-B in Table 1 which are solvent-containing type trially crosslinked polyrotaxanes. For comparison, the urethane gel of Comparative Example 2 was also subjected to the test. A ring specimen made of SUJ-2 steel material that was quenched and tempered to Vickers hardness HV740 was used as the counterpart material. The apparent contact area of the friction surface is 200 mm ² . The specimen was used after being polished with # 600 emery paper. As the lubricant, (1) Water-B (Example 1) was evaluated using water, and (2) PEG-B (Example 2) and comparative urethane gel (Comparative Example 2) had a weight average molecular weight. 300 polyethylene glycols were used. Lubricant temperature was set to room temperature (about 22 ° C.).

  In this test, the coefficient of friction under a plurality of surface pressure conditions was measured by gradually increasing the load load to 20, 49, 98, 147, 196, 294, 392, and 490N. In each surface pressure condition, the friction coefficient was measured while gradually changing the sliding speed to 100, 220, 460 and 1,000 mm / s every 3 minutes.

  When changing the surface pressure condition, the state of occurrence of wear and damage on the sliding surface of the specimen was visually observed, and the test was interrupted if there was significant wear or damage. The test was also interrupted when a sudden increase in the coefficient of friction occurred during the test. In this series of tests, the maximum surface pressure condition that did not cause significant increase in wear and friction coefficient was used as an evaluation scale for load bearing performance. Further, the wear resistance of various test materials was evaluated based on the wear depth of the test plate specimen after the test was completed.

  Similarly, (4) (Example 3) to (7) (Example 6) of Table 1, which is a prototype crosslinked polyrotaxane of a type not containing a solvent, was continuously contacted by a plate-on-ring friction test. The friction and wear characteristics under the conditions were evaluated. As a lubricating oil, a commercial diesel engine oil of DL-1 standard and viscosity grade 5W-30 was used.

[Evaluation under intermittent contact conditions]
By the plate-on-bar friction test shown in FIG. 3, the friction and wear characteristics of the specimens under intermittent contact sliding conditions under engine oil lubrication were evaluated. This evaluation condition simulates intermittent contact conditions such as when the cylinder liner surface of the internal combustion engine slides with the piston ring of the counterpart material. As a counterpart material, a bar specimen made of SUJ-2 steel material which was quenched and tempered to Vickers hardness HV740 was used. The tip radius of curvature is 15 mm, and the surface roughness is 0.8 μm Rzjis. As the lubricating oil, a commercial gasoline engine oil of SM standard and viscosity grade 5W-30 was used. The lubricating oil temperature was set to room temperature (about 22 ° C.) as in the plate-on-ring friction test described above.

  The test conditions were also similar to the plate-on-ring friction test, while changing the sliding speed in steps of 100, 220, 460 and 1000 mm / s every 3 min under the respective surface pressure conditions, The coefficient of friction was measured for each condition, increasing in steps of 49, 98, 147, 196, 294, 392 and 588N. Similarly to the plate-on-ring test, when the load was increased, the state of wear or damage on the sliding surface was visually observed, and the test was interrupted if significant wear or damage occurred. The test was also interrupted when a sudden increase in the coefficient of friction occurred during the test. The maximum surface pressure condition that did not cause significant increase in wear and friction coefficient was used as an evaluation scale for the load bearing performance of the specimen.

  Further, the wear resistance of various test materials was evaluated based on the wear depth of the test plate specimen after the test was completed.

<Evaluation results of friction and wear characteristics>
[Friction and wear characteristics under continuous contact conditions]
FIG. 4 shows the results of evaluating the friction coefficient of the solvent-containing type prototype crosslinked polyrotaxane under continuous contact conditions at a surface pressure of 0.24 MPa (= load 49 N). It can be seen that the test crosslinked polyrotaxane has a lower coefficient of friction than the urethane gel used for comparison and exhibits excellent low friction characteristics under any sliding conditions. However, when the surface was observed immediately after the test under a surface pressure of 0.24 MPa, both Water-B and PEG-B had cracks. Therefore, the surface pressure was 0.49 MPa (= 98 N) or more. The test was interrupted.

FIG. 5 shows the results of evaluating the coefficient of friction under engine oil lubrication and continuous contact conditions at a surface pressure of 0.49 MPa for the prototype crosslinked polyrotaxane of the solvent-containing type and the solvent-free type. The sliding speed 100 mm / s conditions, in all the solvent-free type of crosslinked polyrotaxane having a Martens hardness HM9N / mm ² or more hardness, and wear resistance is obtained can be evaluated friction properties, the friction coefficient can be measured Met. On the other hand, in the case of water and PPG of the solvent-containing type of crosslinked polyrotaxane containing water or polyethylene glycol having HM of 0.3 and 2.3 N / mm ² respectively, a significant increase in friction immediately after the start of the test and the SUS of the plate specimen Because the crosslinked polyrotaxane was worn until the substrate was exposed, the coefficient of friction could not be measured. Therefore, from the viewpoint of ensuring wear resistance, it is judged that it is preferable that the solvent-free type and the Martens hardness be HM3N / mm ² or more.

  In addition, all of the non-solvent-containing crosslinked polyrotaxanes exhibiting superior wear resistance compared to the solvent-containing type have hydrogen atoms of some hydroxyl groups of the cyclic molecule as hydroxypropyl groups, butylcarbamoyl groups, and acetyl groups. It is considered that the lipophilicity is improved. Therefore, it is presumed that not only the absence of the solvent but also the improvement of the lipophilicity is one factor that makes it easy to retain the lubricating oil film and that provides good wear resistance. Further, the solvent-free type crosslinked polyrotaxane is provided as a crosslinked molecule by combining alkoxysilane, isocyanate, or polyisocyanate with an isocyanate alkoxysilane compound. Compared to the glycidyl ether, the solvent-free type Film1-A, Film2, Film4 and Film5 showed superior wear resistance compared to the solvent-containing type crosslinked polyrotaxane provided with glycidyl ether as a crosslinking molecule. It is also considered that molecules that have been crosslinked with alkoxysilane, isocyanate or a combination of polyisocyanate and isocyanate alkoxysilane compounds have higher molecular binding strength and are less likely to cause breakage or detachment of the crosslinking point due to shear. It is done.

Under the conditions of a surface pressure of 0.49 MPa and a sliding speed of 220 mm / s or more, Film ² , Film 4 and Film 5 having a Martens hardness of HM 26 N / mm ² or more showed sufficient wear resistance, and the coefficient of friction was measurable. On the other hand, with respect to the crosslinked polyrotaxane of the solvent-free type, HM is 9 N / mm ² and soft Film 1-A, since the friction speed and excessive wear were significantly increased immediately after setting the sliding speed to 220 mm / s. The test was interrupted. Therefore, it is judged that the Martens hardness is HM10 N / mm ² or more from the viewpoint of ensuring the wear resistance.

Focusing on the friction coefficient, Film4 and Film5 Martens hardness HM, respectively ^{71N / mm 2, 110N / mm} 2 , the friction coefficient in comparison with the polyamide-imide resin composites is smaller, as a low friction sliding material It shows desirable characteristics. In particular, Film4 and Film5 are dependent on the sliding speed (v) of the coefficient of friction (μ), that is, the μ-v characteristic has a positive gradient tendency, and abnormal noise caused by friction such as stick-slip phenomenon and shudder phenomenon. It has become clear that it has excellent characteristics in preventing the occurrence of vibrations.

The evaluation result of the friction characteristic in the continuous contact condition on the surface pressure of 0.98 MPa is shown in FIG. It is confirmed that the solvent-free types Film2, Film4, and Film5 having a Martens hardness HM of 26 N / mm ² or more have desirable wear resistance without causing excessive wear even under a surface pressure of 0.98 MPa. It was done. However, with respect to Film 4 having a Martens hardness HM of 71 N / mm ² , the friction coefficient is increased under the surface pressure condition of 0.98 MPa shown in FIG. 6 as compared with the surface pressure condition of 0.49 MPa shown in FIG. . On the other hand, Film 5 having a hardness of HM110 N / mm ² exhibits a smaller coefficient of friction than the conventional polyamide-imide resin composite material even under a surface pressure of 0.98 MPa, and its μ-v characteristic has a positive slope. It has been found that it has been found to have particularly desirable low friction properties as well as anti-shudder properties.

The load bearing performance of various crosslinked polyrotaxanes in a friction test under continuous contact conditions is shown in FIG. In general, it can be seen that the load bearing performance improves as the Martens hardness HM increases. It can be seen that in Film 5 having HM110 N / mm ² , excellent load bearing performance up to a surface pressure of 2.4 MPa is obtained.

  FIG. 8 shows the result of measuring the roughness shape in the vicinity of a typical crosslinked polyrotaxane sliding surface after a series of friction tests using a non-contact three-dimensional surface shape measuring instrument (Zygo, New View 5022). In Film 5, which showed a small friction coefficient compared to the polyamide-imide resin composite up to a surface pressure condition of 0.98 MPa, although scratches are locally generated, the film is generally smoother than other crosslinked polyrotaxanes. It can be seen that it has a sliding surface. In Film 5, it is considered that the formation of an oil film by lubricating oil was promoted by such smoothing of the surface as a factor that particularly excellent low friction characteristics were obtained.

[Friction and wear characteristics under intermittent contact conditions]
FIG. 9 shows the friction characteristics of Film 5 and polyamide-imide resin composite material under intermittent contact conditions evaluated by a plate-on-bar test. In this plate-on-bar friction test, the contact form is a line contact form, and the maximum Hertz pressure under the present evaluation condition with a load of 588 N is 272 MPa in terms of a conversion value when a steel specimen is used. Even under such a high surface pressure condition, it was found that Film 5 exhibits excellent low friction characteristics as compared with the conventional polyamideimide resin composite material.

  FIG. 10 shows the roughness of the sliding surface after the friction test measured by a non-contact three-dimensional surface shape measuring machine. Film 5 has a smoother surface than the polyamide-imide resin composite. This is presumably due to the fact that in Film 5 having a cross-linked structure with cyclic molecules, plastic flow of the material due to the shear force of friction occurs, and the surface is thereby smoothed. In addition, such smoothing of the surface is considered to contribute to the reduction of friction through the promotion of oil film formation, similar to the discussion on the results under the continuous contact conditions described in the previous section.

  The result of having measured the surface shape of Film5 after the test on each condition of a continuous contact and an intermittent contact with the stylus type surface shape measuring device is shown in FIG. The amount of decrease in height of the sliding portion relative to the non-sliding portion means the amount of wear or plastic deformation. In FIG. 11 b), the actual maximum Hertz pressure in a plate-on-bar test at a load of 588 N calculated using the Young's modulus of Film 5 is added. It can be seen that in the intermittent contact condition of b), the wear depth or the amount of plastic deformation is small although the maximum surface pressure is higher by one digit or more than in the continuous contact condition of a). In the surface under the continuous contact condition shown in FIG. 11a), although the height reduction of the sliding part from the non-sliding part is large, the boundary between both parts is raised, It is judged that the amount of height reduction is not only due to wear but also due to plastic flow. On the other hand, in the intermittent contact state, such plastic flow marks of the entire contact portion are not recognized. In the contact state in which the load and the load of the shearing force are intermittent, it is considered that the overall plastic flow is reduced by repeating deformation and restoration within a range where the crosslinked polyrotaxane is within the elastic deformation amount. In a sliding member, although the slight plastic flow that smoothes the surface described above has little effect on the overall shape change and does not pose a problem, it is an excessive component that the entire sliding surface is recessed by plastic flow. This creates a problem because of the clearance. Therefore, it can be said that the application of the crosslinked polyrotaxane, which is likely to cause plastic flow, as a sliding member is preferably applied to parts and parts that have intermittent contact conditions.

  FIG. 12 shows the surface shapes of Film 5 and the polyamideimide resin composite material after the intermittent contact test measured using a stylus type surface shape measuring instrument. It has been found that Film 5 has less wear or plastic deformation than the conventional polyamide-imide resin composite and has excellent wear resistance.

FIG. 12 also shows the actual maximum Hertz pressure under the condition of a load of 588 N calculated using the actual Young's modulus of the member used as the plate test piece. When Film 5 is used, the maximum Hertz pressure is 27 MPa, and the value is smaller than 50 MPa of the polyamide-imide resin composite and 272 MPa when the steel material shown in FIG. 9 is used. That is, when a cross-linked polyrotaxane having a small elastic modulus is used on the sliding surface, it can be said that the actual maximum surface pressure can be reduced as compared with conventional resin materials and metal materials. Although the reduction of the actual maximum surface pressure under the same load condition is also softer than that of the polyamide-imide resin composite material having HM284 N / mm ² , Film 5 showed excellent wear resistance. It is assumed that this is a factor.

  10 linear molecule, 12 cyclic molecule, 14 blocking group, 16 modifying group, 18 crosslinking group.

Claims (10)

  At least a sliding surface that slides with the mating member is disposed at both ends of the cyclic molecule, the linear molecule that includes the cyclic molecule in a skewered manner, and the detachment of the cyclic molecule. A sliding member comprising a crosslinked polyrotaxane constituted by crosslinking of the cyclic molecules in a polyrotaxane having a blocking group to be prevented. The sliding member according to claim 1,
The sliding member, wherein the cyclic molecule is at least one selected from the group consisting of α-cyclodextrin, β-cyclodextrin, and γ-cyclodextrin. The sliding member according to claim 2,
Hydrogen atoms of some or all of the hydroxyl groups of the cyclic molecule are substituted with at least one modification group selected from substituents represented by the following formulas (I-1) to (I-3). A sliding member characterized by that.

(Wherein R ₁₁ , R ₁₂ and R ₁₃ are each independently a linear or branched alkyl group having 1 to 12 carbon atoms, or the R _{11 to} R ₁₃ are a hydroxyl group, It may be substituted with at least one selected from the group consisting of a carboxyl group, an acyl group, a phenyl group, a halogen atom, and (R ₁₄ O) ₃ —Si—, and each R ₁₄ independently has 1 carbon atom. ˜3 alkyl or branched alkyl groups, wherein each of R ₁₄ may be the same or different. The sliding member according to claim 3,
The cyclic molecule is α-cyclodextrin, and the hydrogen atoms of some or all of the hydroxyl groups of the cyclic molecule are a hydroxypropyl group, a butylcarbamoyl group, an acetyl group, and a 3- (triethoxysilyl) propylcarbamoyl group. A sliding member substituted with at least one modification group selected from The sliding member according to any one of claims 1 to 4,
The sliding member, wherein the linear molecule is polyethylene glycol. The sliding member according to any one of claims 1 to 5,
The sliding member, wherein the crosslinked polyrotaxane is substantially free of a solvent component. The sliding member according to any one of claims 1 to 6,
A sliding member, wherein the crosslinking is performed with at least one crosslinking agent selected from the group consisting of an isocyanate compound, a glycidyl ether compound, an alkoxysilane compound, and an imidazole compound. The sliding member according to any one of claims 1 to 7,
A sliding member, wherein the cross-linked polyrotaxane has a Martens hardness HM of 3 N / mm ² or more.   The sliding member according to any one of claims 1 to 8, wherein the sliding member is in an intermittent contact state in which a load with a surface pressure of 0.1 MPa or more and a release thereof are repeated. A sliding component characterized in that it is provided.   A sliding bearing, an oil seal, a sliding guide, and a guide rail, wherein the sliding member according to any one of claims 1 to 8 is provided on at least a part of the sliding surface and is used in a usage condition in which a lubricant is present. , Pistons, piston rings for internal combustion engines, cylinders, sliders, washers, valve-operated parts, friction power transmission devices (clutches) and laminated rings and elements used for power transmission belts of belt-type continuously variable transmissions A sliding component characterized by being one.