JP2015124311A - Sliding resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sliding resin composition that improves in friction such as frictional property and wear resistance.SOLUTION: A sliding resin composition comprises 5-30 vol.% of an ultrahigh-molecular weight polymer with an average molecular weight of 500,000 or more and less than 3000,000, wherein the ultrahigh-molecular weight polymer is at least one selected from polytetrafluoroethylene, polyethylene and polyamide.

Description

  The present invention relates to a sliding resin composition and a sliding member having a sliding surface coated with the resin composition.

  In automobiles, sliding members are used in various devices such as engines and transmissions, and various developments have been made to improve the sliding characteristics of such sliding members. Reducing the coefficient of friction of the sliding member is particularly important because it leads to an improvement in the fuel consumption of the automobile. In recent years, the demand for smaller and lighter engines has increased, and the lubrication state of sliding members has been increasing, such as reducing the area of the piston skirt around the piston and reducing the clearance between the piston skirt surface and the cylinder bore. It's getting tough.

  As one means for reducing the friction coefficient of the sliding member, a resin composition is applied to the sliding member such as a piston skirt. In many cases, this resin composition contains a heat-resistant resin and an additive. As additives, it is known that alumina improves wear resistance, and molybdenum disulfide, graphite and PTFE (polytetrafluoroethylene) improve friction characteristics. A resin composition for a sliding member using an ultrahigh molecular weight polymer as an additive is also known.

  For example, Patent Document 1 includes (A) number average molecular weight of 10 to 20 million, polytetrafluoroethylene having an average particle size of 50 to 200 μm, 50 to 75% by mass, (B) number average molecular weight of 10,000 to 200,000, Polytetrafluoroethylene having an average particle diameter of 3 to 35 μm, 50 to 25% by mass, (C) From 95 to 60% by mass of the polyamide resin with respect to the total amount of components (A) and (B) of 5 to 40% by mass A thermoplastic resin composition for a sliding member is described.

  Patent Document 2 includes 50 to 80% by volume of thermosetting resin, 10 to 40% by volume of polytetrafluoroethylene having a molecular weight of 3 million or more, and 1 to 20% by volume of bismuth and / or bismuth alloy. A sliding composition characterized in that is described.

  However, even when such a resin composition is applied to a sliding member, it is a top dead center that is a boundary lubrication state in which there is almost no oil, and an intermediate state between fluid lubrication and boundary lubrication, and is relatively fluid. In the vicinity of the bottom dead center, which is a mixed state close to the lubrication state, the speed of the sliding member such as the piston becomes zero, and no oil film is formed, so that the friction is greatly increased.

  Therefore, it is required to reduce friction such as friction characteristics and wear resistance of the sliding member at the top dead center and the bottom dead center.

JP 2007-70537 A JP 2004-115577 A

  As described above, when the conventional resin composition is applied to the sliding member, the friction greatly increases in the vicinity of the top dead center and the bottom dead center, so there is room for improvement in friction such as friction characteristics and wear resistance. There is.

  Therefore, an object of the present invention is to provide a sliding resin composition having improved friction such as friction characteristics and wear resistance.

  As a result of various studies on means for solving the above problems, the inventors have blended a specific amount of a specific ultrahigh molecular weight polymer having an average molecular weight of 500,000 to less than 3 million into the sliding resin composition, The present inventors have found that the friction characteristics and wear characteristics are improved, thereby completing the present invention.

That is, the gist of the present invention is as follows.
(1) A sliding resin composition comprising 5 to 30% by volume of an ultrahigh molecular weight polymer having an average molecular weight of 500,000 to less than 3 million, wherein the ultrahigh molecular weight polymer is selected from polytetrafluoroethylene, polyethylene and polyamide A sliding resin composition which is at least one kind.
(2) The sliding resin composition according to (1), wherein the ultrahigh molecular weight polymer is polytetrafluoroethylene.
(3) The sliding resin composition according to (1) or (2), wherein the ultra-high molecular weight polymer has an average particle size of 0.1 μm to 10 μm.
(4) Any of (1) to (3), wherein the resin is at least one selected from polyimide resin, polyamideimide resin, polyethersulfone resin, polyphenylsulfide resin, polyamide resin, epoxy resin, and phenol resin Such a sliding resin composition.
(5) The sliding resin composition according to any one of (1) to (4), further comprising at least one solid lubricant selected from polytetrafluoroethylene, molybdenum disulfide, and graphite having an average molecular weight of less than 500,000 object.
(6) The sliding resin composition according to any one of (1) to (5), further comprising at least one kind of hard particles selected from alumina and silica.
(7) A sliding member that is used in a wet condition using a lubricating oil, and the sliding resin composition according to any one of (1) to (6) is coated on a sliding surface.

  According to the present invention, it is possible to provide a sliding resin composition excellent in friction characteristics and wear resistance and a sliding member provided with the coating composition on a sliding surface.

FIG. 1 is a diagram showing an outline of a method for evaluating friction characteristics. FIG. 2 is a diagram showing an outline of a method for evaluating wear characteristics. FIG. 3 is a diagram showing the friction coefficients obtained in Examples 1 to 4 and Comparative Examples 1 to 4 in Examples of the present invention. FIG. 4 is a graph showing the amount of wear in Examples 1 to 4 and Comparative Examples 1 to 4 in Examples of the present invention. FIG. 5 is a diagram showing the friction coefficients obtained in Example 5 and Comparative Examples 5 to 10 in the examples of the present invention. FIG. 6 is a diagram showing the friction coefficients obtained in Examples 6 to 19 and Comparative Example 1 in Examples of the present invention. FIG. 7 is a diagram showing the seizure loads obtained in Examples 6 to 19 and Comparative Example 1 in the examples of the present invention. FIG. 8 is a diagram showing an outline of a method for evaluating seizure characteristics. FIG. 9 is a diagram showing an outline of a method for evaluating peeling characteristics. FIG. 10 is a graph showing the relationship between the average particle size of ultrahigh molecular weight polytetrafluoroethylene and the coefficient of friction in the examples of the present invention. FIG. 11 is a diagram showing the difference in FMEP of the resin compositions of Example 25 and Comparative Example 1 in the examples of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail.
1. Sliding resin composition TECHNICAL FIELD This invention relates to the sliding resin composition. The resin composition of the present invention is a resin composition for a sliding member used under wet conditions using a lubricating oil.

  The sliding resin composition of the present invention comprises a resin and an ultrahigh molecular weight polymer having an average molecular weight of 500,000 to less than 3 million. The ultra high molecular weight polymer is a lubricating oil retaining component, and can be refined by shearing by sliding to increase the viscosity of the lubricating oil on the outermost surface of the sliding member by affinity with the lubricating oil. For this reason, by adding an ultra-high molecular weight polymer to the resin composition, an oil film is actively formed near the top dead center / bottom dead center where the speed of the sliding member such as a piston becomes zero, and friction is applied. Can be reduced.

  The ultrahigh molecular weight polymer used in the sliding resin composition of the present invention is at least one selected from polytetrafluoroethylene (PTFE), polyethylene, and polyamide, and is preferably polytetrafluoroethylene.

  The ultra high molecular weight polymer used in the sliding resin composition of the present invention has an average molecular weight of 500,000 or more and less than 3 million. When the average molecular weight of the ultrahigh molecular weight polymer is less than 500,000, the effect of increasing the viscosity of the lubricating oil is low, so that a sufficient friction reducing effect cannot be obtained. On the other hand, when the average molecular weight of the ultrahigh molecular weight polymer is 3 million or more, the ultrahigh molecular weight polymer is difficult to be miniaturized due to shearing by sliding, so that a sufficient friction reducing effect cannot be obtained.

  The average particle size of the ultrahigh molecular weight polymer used in the sliding resin composition of the present invention can be appropriately selected according to the film thickness of the film formed by coating the resin composition. From the viewpoints of ease of miniaturization, coating properties of the resin composition, and good surface roughness of the film formed by coating, the thickness is preferably 0.1 μm to 10 μm. The average particle diameter can be determined by a laser diffraction scattering method.

  The resin used in the sliding resin composition of the present invention is not particularly limited, and is a heat resistant resin having a heat distortion temperature of 100 ° C. or higher, preferably 150 ° C. or higher. Examples of the heat-resistant resin are not particularly limited, but are not limited to polyimide resin, polyamideimide resin, polyetherimide resin, polyethersulfone resin, polyphenylsulfide resin, polyamide resin, alkyd resin, epoxy resin, amino resin, polyamino Amide resin, unsaturated polyester resin, phenol resin, xylene resin, vinyl ester resin, furan resin, silicone resin and wholly aromatic polyester resin can be mentioned, but from the viewpoint of adhesiveness, chemical resistance, strength, etc. Polyimide resin, polyamideimide resin, polyethersulfone resin, polyphenylsulfide resin, polyamide resin, epoxy resin and phenol resin are preferable. Polyamide resin is used from the viewpoint of workability during film formation and heat resistance against heat generated by friction. Resin is more preferable. These heat resistant resins may be used alone or in combination of two or more.

  The content of the resin in the composition is preferably 40% by volume to 97% by volume, more preferably 60% by volume to 90% by volume, particularly preferably from the viewpoint of maintaining the strength of the resin composition. Is 70% to 85% by volume.

The sliding resin composition of the present invention can further contain one or more solid lubricants in order to improve the friction characteristics. The solid lubricant that can be used in the composition of the present invention is not particularly limited. For example, polytetrafluorothiethylene (PTFE) (average molecular weight less than 500,000), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer Polymers, fluorine compounds such as tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-ethylene copolymer, polyvinylidene fluoride and polychlorotrifluoroethylene, molybdenum disulfide (MoS ₂ ) and tungsten disulfide (WS) ₂ ) sulfides, graphite (graphite), fluorinated graphite, boron nitride, mica and other lamellar substances, soft metals such as lead, zinc and copper, melamine cyanurate, etc. From the viewpoint of maintaining high self-sliding properties, polytetrafluoroethylene, Molybdenum and graphite are preferred. These may be used alone or in combination of two or more.

  The content of one or more solid lubricants in the composition is not particularly limited and can be selected according to the type of solid lubricant used, for example, polytetrafluoroethylene is in an amount of 20% by volume or less. Molybdenum disulfide is contained in the composition in an amount of 30% by volume or less, and graphite is contained in an amount of 20% by volume or less. When a solid lubricant is used in an amount within this range, a sufficient friction reducing effect can be obtained without affecting the seizure resistance, and the coating formed by coating the base of the sliding member with a resin composition. Can maintain sufficient strength without peeling from the substrate.

In addition, the sliding resin composition of the present invention can further contain one or more kinds of hard particles in order to improve wear resistance and seizure resistance. The hard particles that can be used in the composition of the present invention are not particularly limited, but alumina (aluminum oxide) (Al ₂ O ₃ ), aluminum hydroxide, alumina white, silica alumina, zirconia, tungsten carbide, titanium carbide , Silicon carbide, titanium dioxide, iron oxide, feldspar, pumice, orthoclase, iridium, quartz, silica, beryllium oxide, zirconium oxide, chromium, boron carbide, tungsten carbide, silicone carbide, diamond, etc. Alumina and silica are preferred. Only one hard particle may be used alone, or two or more hard particles may be used in combination.

  The content of the one or more hard particles in the composition is not particularly limited as long as the strength of the film formed by coating the resin composition can be maintained. For example, alumina is 10% by volume or less. In the composition.

  The sliding resin composition of the present invention can also contain other general additives other than the above-mentioned components. Additives include solid lubricants and dispersants for dispersing hard particles, silane coupling agents that help improve affinity and adhesion to hard particles, leveling agents and surfactants that control surface tension And thickeners and pigments for controlling thixotropic properties. Examples of the pigment include color pigments typified by carbon black, titanium oxide, and iron oxide, rust preventive pigments that suppress the generation of rust, and extender pigments that control the properties of the film.

  The sliding resin composition of the present invention can also contain an organic solvent for dissolving the heat resistant resin. The organic solvent that can be used in the present invention is not particularly limited and is selected according to the type of the heat-resistant resin. For example, when a polyamideimide resin is used as the heat resistant resin, N-methyl-2-pyrrolidone (NMP), N-ethylpyrrolidone (NEP), 1,3-dimethyl-2-imidazolidinone (DMI) and γ -Butyrolactone can be used. Moreover, when using an epoxy resin, methyl ethyl ketone, toluene, etc. can be used.

  The resin composition of the present invention is prepared, for example, by preparing a solution obtained by dissolving the above heat-resistant resin in an organic solvent, ultrahigh molecular weight polymer, and solid lubricant, hard particles, and other general additions as required. It can be prepared by mixing the agent into this solution.

2. Sliding member The present invention also relates to a sliding member which is used under wet conditions using a lubricating oil and whose sliding surface is coated with the sliding resin composition. The sliding member of the present invention is characterized in that the coated resin composition contains a specific amount of an ultrahigh molecular weight polymer having a specific molecular weight. Thereby, the sliding member exhibits excellent friction characteristics and wear characteristics.

  The sliding member of the present invention can be obtained by coating the sliding resin composition on the sliding surface of the base member of the sliding member.

  In the present invention, the sliding member means a mechanical part having a sliding part, and specifically includes a wet clutch, an engine piston, a gear, a spline, a bearing, a washer, and a valve operating system part. The sliding member of the present invention is intended to slide under wet conditions using lubricating oil.

  The base material of the sliding member of the present invention is not particularly limited in shape as long as it is a sliding part of various apparatuses, and may be any of a metal base material, a ceramic base material, a resin base material, etc. It is preferably made of metal. The metal constituting the substrate is preferably an aluminum alloy containing Cμ, Mg, Zn and the like in addition to cast iron, steel and aluminum, and a copper alloy containing Zn, Al, Sn and the like in addition to copper.

  The method for coating the base of the sliding resin composition is not particularly limited, and a known coating method such as spray coating can be used, and then the heat-resistant resin can be dried and cured. By baking, a resin composition can be obtained. The firing conditions are not particularly limited, and are, for example, 30 minutes to 3 hours at a temperature of 100 ° C. to 370 ° C.

The lubricating oil used for the sliding member of the present invention is not particularly limited. For example, ATF (automatic transmission oil), CVTF (continuously variable transmission oil), drive oil such as gear oil, gasoline, light oil, etc. Fuel oil, engine oil and the like.
The sliding member of the present invention can be a piston, a bearing, a washer or the like.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the technical scope of the present invention is not limited to these examples.

Example 1: Creating a test piece
80% by volume of polyamideimide resin (PAI resin) was dissolved in N-methyl-2-pyrrolidone (NMP). 5% by volume of polytetrafluoroethylene (PTFE) having an average molecular weight of 2 million was added to the obtained solution of polyamideimide resin and kneaded for 1 hour to obtain a resin composition.

  The obtained resin composition is spray-coated on the surface of a plate-shaped substrate made of cast aluminum AC8A, and baked at 180 ° C. for 90 minutes to volatilize N-methyl-2-pyrrolidone, thereby having a film thickness of about 10 μm. A coating was formed to produce a test piece for evaluation of friction characteristics.

  The resulting resin composition is spray coated on the surface of a block-shaped substrate made of cast aluminum AC8A, and baked at 180 ° C for 90 minutes to evaporate the organic solvent, thereby forming a film with a thickness of about 10 µm. A block test piece for evaluating wear characteristics was formed.

1. Evaluation of friction characteristics As shown in Fig. 1, the friction characteristics were evaluated by pressing a bearing ball of SUJ2 with a diameter of 10 mm against the upper surface of a flat test piece. The test conditions were as follows: 1 mg of engine oil was uniformly dropped onto the plate (58 x 38 mm), and the average friction coefficient was evaluated in a 50 reciprocating rocking test at a load of 10 N and a sliding speed of 2 Hz (maximum 0.1 m / s). . Since the amount of oil is very small and the test is under poor lubrication conditions, it can be said that the test reproduces the lubrication state near the top and bottom dead center in the piston behavior.

2. Evaluation of wear characteristics As shown in Fig. 2, the wear characteristics were evaluated by pressing the block test piece against the side of a mating cylindrical test piece made of gray cast iron FC250. The test condition was that the wear characteristics were evaluated by measuring the wear depth of the coating layer after performing a wear test for a fixed time at a test surface pressure of 30 MPa after running-in operation in engine oil (80 ° C.).

Examples 2-4
The same procedure as in Example 1 was conducted except that the polytetrafluoroethylene content was changed to 10, 20, and 30% by volume, and the amount of the polyamideimide resin was changed accordingly. Table 1 shows the compositions of the resin compositions of Examples 2 to 4.

Comparative Example 1
As a conventional resin composition, using N-methyl-2-pyrrolidone (NMP) as an organic solvent, 86 volume% polyamideimide resin, 7 volume% molybdenum disulfide (MoS ₂ ), 2 volume% graphite and 5% A composition containing% by volume of Teflon (polytetrafluoroethylene) was used. This composition was prepared as described in JP-A-7-97517. Table 1 shows the composition of the resin composition of Comparative Example 1.

Comparative Examples 2-4
The same procedure as in Example 1 was conducted, except that the polytetrafluoroethylene content was changed to 1, 3, and 50% by volume, and the amount of the polyamideimide resin was changed accordingly. Table 1 shows the compositions of the resin compositions of Comparative Examples 2 to 4.

  The evaluation of the coefficient of friction obtained in Examples 1 to 4 and Comparative Examples 1 to 4 is shown in FIG. In Examples 1 to 4, the friction coefficient was significantly reduced compared to Comparative Examples 1 to 4. When Examples 1 to 4 were compared with Comparative Example 1, it was shown that the coefficient of friction was greatly reduced by adding polytetrafluoroethylene having an average molecular weight of 2 million. In addition, a decrease in the friction coefficient is observed as the polytetrafluoroethylene content increases, but when the polytetrafluoroethylene content exceeds 30% by volume, the value of the friction coefficient gradually approaches a constant value. (Example 4, Comparative Example 4).

  Further, FIG. 4 shows graphs of the wear amounts of Examples 1 to 4 and Comparative Examples 1 to 4. As the polytetrafluoroethylene content increases, the amount of wear increases, and when polytetrafluoroethylene is 50% by volume (Comparative Example 4), the amount of wear is about 12.5 μm, the lower limit for obtaining material reliability. The amount of wear was greater than about 10 μm.

  3 and 4, the content of the ultrahigh molecular weight polymer in the resin composition is preferably 5 to 30% by volume, and more preferably 10 to 20% by volume.

Example 5
Example 3 was repeated except that the polyamideimide resin was changed to an epoxy resin. Table 2 shows the composition of the resin composition of Example 5.

Comparative Examples 5-10
In Comparative Example 5, a resin composition was prepared in the same manner as Example 1 without using polytetrafluoroethylene having an average molecular weight of 2 million. In Comparative Examples 6 to 8, resin compositions were prepared in the same manner as in Example 3, except that the molecular weight of polytetrafluoroethylene was changed from the molecular weight of Example 3 to the molecular weight described in Table 2. Comparative Examples 9 and 10 were the same as Example 3 except that molybdenum disulfide (MoS ₂ ) (Comparative Example 9) and graphite (Comparative Example 10) were used instead of polytetrafluoroethylene. Table 2 shows the compositions of the resin compositions of Comparative Examples 5 to 10.

The evaluation of the friction coefficient obtained in Example 5 and Comparative Examples 5 to 10 is shown in FIG. Example 5 showed the same coefficient of friction as Example 3, and an epoxy resin (however, an amino resin was used as a curing agent) could be used as the heat-resistant resin in the same manner as the polyamide-imide resin. Further, when polytetrafluoroethylene having an average molecular weight of 2 million was not used (Comparative Example 5), or when polytetrafluoroethylene having a molecular weight different from that of Example 3 was used, it was compared with Example 3. The friction reducing effect was small. Also implemented in the case of using molybdenum disulfide (MoS ₂ ) (Comparative Example 9) and graphite (Comparative Example 10), which are solid lubricants with extremely low oil absorption characteristics instead of polytetrafluoroethylene with an average molecular weight of 2 million. Compared with Example 3, the friction reducing effect was small.

[Effects of blending amount of solid lubricant and hard particles on friction coefficient, seizure characteristics, and peeling characteristics]
In Examples 6 to 19, the influence of the blending amount of the solid lubricant and the hard particles on the friction coefficient was evaluated. Examples 6 to 8 were the same as Example 3 except that molybdenum disulfide (MoS ₂ ) was used in a predetermined amount as a solid lubricant, and the amount of polyamideimide resin was changed accordingly. Examples 9 to 11 were the same as Example 3 except that graphite was used in a predetermined amount as a solid lubricant, and the amount of polyamideimide resin was changed accordingly. In Examples 12 to 14, except that Teflon (registered trademark) (polytetrafluoroethylene) having an average molecular weight of 20,000 to 30,000 was used as a solid lubricant in predetermined amounts, and the amount of polyamideimide resin was changed accordingly. Was the same as in Example 3. In Examples 15 and 16, molybdenum disulfide (MoS ₂ ), graphite, and Teflon (registered trademark) having an average molecular weight of 20,000 to 30,000 were used as solid lubricants in predetermined amounts, respectively, and the amount of polyamideimide resin corresponding thereto Example 3 was repeated except that In Examples 17 to 19, molybdenum disulfide (MoS ₂ ), graphite, and Teflon (registered trademark) having an average molecular weight of 20,000 to 30,000 are used as solid lubricants in predetermined amounts, respectively, and alumina (Al ₂ O ₃ ) is used as hard particles. ) Was used in a predetermined amount, and the same procedure as in Example 3 was performed except that the amount of polyamideimide resin was changed accordingly. Table 3 shows the compositions of the resin compositions of Examples 6 to 19.

  The friction coefficients and seizure characteristics obtained in Examples 6 to 19 are shown in FIGS. 6 and 7, respectively, and the evaluation results of the peeling characteristics are shown in Table 3. Evaluation of seizure characteristics and peeling characteristics was performed as follows.

<Evaluation of seizure characteristics>
(1) As a test piece for evaluating seizure characteristics, a test piece for evaluating friction characteristics was used.
(2) As shown in FIG. 8, the rotating flat plate test piece was pressed against the end face of the mating cylindrical test piece made of gray cast iron FC250 to evaluate the seizure characteristics.
(3) The test conditions were as follows: after the leveling operation in engine oil (80 ° C), evaluate the friction characteristics with the coefficient of friction at the test surface pressure of 20MPa when the test load is stepped up, and step the test load When the coating film of the resin composition of the flat plate test piece was worn away or peeled off, the counter agent and the substrate were in direct contact with each other, and the seizure characteristics were evaluated with a load (seizure load) at which the torque increased rapidly.

<Evaluation of peeling properties>
(1) A test piece for evaluating the peeling characteristics was produced in the same manner as the test piece for evaluating the friction characteristics.
(2) As shown in FIG. 9, a bearing ball made of SUJ2 having a diameter of 1/8 inch was pressed against the upper surface of a flat plate test piece to evaluate the peeling characteristics.
(3) The test conditions were as follows: engine oil was evenly applied on a flat plate, the test load was gradually increased to 0.5 to 10N (fluctuated during one stroke), and slid 200 times at a speed of 15mm / sec. The maximum load at which the coating film remained after the test was measured as a peel load and subjected to comparative evaluation.

  In any of Examples 6 to 19, since polytetrafluoroethylene having an average molecular weight of 2 million was blended in the resin composition, the coefficient of friction was significantly reduced as compared with Comparative Example 1. Further, regarding the seizure characteristics of Examples 6 to 19, the seizure surface pressure is 20 MPa or more, and it is considered that there is no problem in use as a sliding member. However, as a result of the release characteristics, when the blending amount of the solid lubricant and the hard particles is increased, the coating formed by coating the resin composition is increasingly weakened, and the coating is more easily peeled off. Based on the above results, polytetrafluoroethylene having an average molecular weight of less than 500,000 as a solid lubricant is 20 volume% or less, molybdenum disulfide is 30 volume% or less, and graphite is 20 volume% or less. It is preferable to be contained in the composition, and alumina as hard particles is preferably contained in the composition in an amount of 10% by volume or less.

[Effect of average particle size of ultrahigh molecular weight polymer on friction coefficient]
The influence of the average particle size of the ultrahigh molecular weight polytetrafluoroethylene on the friction coefficient in the resin composition of the present invention was examined. For the resin composition of Example 3, prepared an ultra high molecular weight polytetrafluoroethylene having an average particle size of 0.1, 1, 5, 10, 20 μm (Examples 20 to 24, respectively), and a coating with a film thickness of 10 μm A test piece for evaluation of frictional characteristics formed with was produced and evaluated. The obtained results are shown in Table 4 and FIG.

  From Table 4 and FIG. 10, when the average particle size of the ultrahigh molecular weight polytetrafluoroethylene is 0.1 μm to 10 μm, an excellent friction reducing effect is obtained, and the coating properties of the resin composition and coating The surface roughness of the formed film was also good.

[Friction evaluation using floating liner type friction measurement engine]
For the resin composition of Example 25 and the resin composition of Comparative Example 1 in which the composition of the resin composition of the present invention was optimized, the effect of reducing friction was confirmed using a floating liner type friction measurement engine.

The composition of the resin composition of Example 25 is shown in Table 5.

The test was conducted by the following method.
(1) The coating composition is screen printed on the skirt surface of a piston made of cast aluminum AC8A using a screen of mesh size No. 100 and baked at 180 ° C for 90 minutes to volatilize N-methyl-2-pyrrolidone. As a result, a piston having a coating thickness of about 10 μm was produced.

(2) A piston ring, etc., is attached to the manufactured piston and incorporated in a floating liner type friction measurement engine, and friction loss is calculated as friction mean effective pressure (FMEP) (value obtained by dividing friction work generated by piston motion by engine stroke volume). ). A cast iron cylinder liner having a surface roughness of 2 to 4 μm in terms of 10-point average roughness (Rz) was used as the counterpart material that slides with the piston. In this apparatus, a frictional force applied to a cylinder liner is measured when a piston slides in a vertical direction by a load measuring sensor coupled by a cylinder liner.

(3) Test conditions for measuring friction with a floating liner type friction measuring engine are an engine speed of 800 to 2400 rpm, a load of 300 to 900 kPa, and a lubricating oil temperature of 80 ° C.

  FIG. 11 shows the difference in FMEP when the resin compositions of Example 25 and Comparative Example 1 are used. In this figure, when the value on the vertical axis is positive, there is no friction reduction effect, and when the value is negative, it means that there is a friction reduction effect. From FIG. 11, it was shown that the resin composition of Example 25 showed an excellent friction reducing effect with respect to the resin composition of Comparative Example 1.

  By using the resin composition of the present invention, it is possible to provide a sliding resin composition having improved friction characteristics and wear resistance.

Claims (7)

  A sliding resin composition comprising 5 to 30% by volume of an ultrahigh molecular weight polymer having an average molecular weight of 500,000 to less than 3 million, wherein the ultrahigh molecular weight polymer is selected from at least polytetrafluoroethylene, polyethylene and polyamide One type of sliding resin composition.   2. The sliding resin composition according to claim 1, wherein the ultrahigh molecular weight polymer is polytetrafluoroethylene.   3. The sliding resin composition according to claim 1 or 2, wherein the ultra high molecular weight polymer has an average particle size of 0.1 μm to 10 μm.   The resin according to any one of claims 1 to 3, wherein the resin is at least one selected from a polyimide resin, a polyamideimide resin, a polyether sulfone resin, a polyphenyl sulfide resin, a polyamide resin, an epoxy resin, and a phenol resin. Kinetic resin composition.   The sliding resin composition according to any one of claims 1 to 4, further comprising at least one solid lubricant selected from polytetrafluoroethylene, molybdenum disulfide, and graphite having an average molecular weight of less than 500,000.   6. The sliding resin composition according to claim 1, further comprising at least one hard particle selected from alumina and silica.   A sliding member, which is used under wet conditions using a lubricating oil, wherein the sliding resin composition according to any one of claims 1 to 6 is coated on a sliding surface.

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