JP2018150528A - Dry lubricant film composition and slide member comprising slide layer constituted by the dry lubricant film composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dry lubricant film composition capable of further improving a slide characteristic of a slide layer formed by the dry lubricant film, and a slide member having the slide layer.SOLUTION: The dry lubricant film composition according to the present invention comprises binder resin and a solid lubricant, wherein the binder resin contains polyamide-imide resin having diphenyl ether as a residue. Further, the slide member according to the present invention comprises a slide layer on a surface of a base material, wherein the slide layer is constituted of the dry lubricant film containing the polyamide-imide resin having the diphenyl ether as the residue and the solid lubricant.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a dry lubricating coating composition and a sliding member having a sliding layer made of the dry lubricating coating composition.

  Conventionally, in sliding members such as bearings for automobile engines, a sliding layer containing a solid lubricant is formed on a metal layer to provide wear resistance, non-seizure properties, and initial conformability. Improvements are being made.

  For example, as shown in Patent Document 1, Patent Document 2, etc., a polyamide-imide resin (PAI resin), a polyimide resin (PI resin), an epoxy resin (EP resin) are formed on the surface of a base material having a cylindrical inner peripheral surface. In order to improve wear resistance, non-seizure property, and initial conformability, a thermosetting resin such as) is coated with a sliding layer containing a solid lubricant or the like. In addition, as shown in Patent Document 3, the protective layer is composed of a solid lubricant and a binder resin made of a thermoplastic resin and a thermosetting resin that is soluble in a polar solvent, while maintaining compatibility. In order to improve the wear resistance at an early stage.

  Further, when using a sliding bearing, a cavity (bubble) is generated in the lubricating oil, and as a result, there is a phenomenon that erosion occurs on the bearing surface. This is a phenomenon in which the cavity generated in the lubricating oil collapses under high pressure, and the energy at the time of collapse causes the bearing surface to be eroded. As a countermeasure, a proposal has been made to improve the cavitation resistance by increasing the material strength of the sliding layer. For example, Patent Document 4 includes a polybenzimidazole resin (PBI resin) containing a solid lubricant or the like. By providing a sliding layer, it is attempted to improve wear resistance, non-seizure property, and cavitation resistance. Further, Patent Document 5 proposes to improve the sliding characteristics by using a solid lubricant containing lead and a resin binder made of at least one of PAI resin, PI resin, EP resin, and PBI resin. .

  In recent years, demands for high performance and high load due to high output and high rotation of an internal combustion engine are increasing, and it is desired to further improve the bearing performance of sliding members such as slide bearings in response to the demand. Yes.

JP-A-4-83914 JP-A-9-79262 JP 2001-343022 A JP 2004-19758 A JP 2003-56566 A

  The present invention has been proposed in view of the above-described conventional situation, and in a sliding member in which a sliding layer is formed by a dry lubricating film, the dryness which can further improve the sliding characteristics of the sliding layer. An object is to provide a lubricating coating composition and a sliding member thereof.

  The inventors of the present invention have made extensive studies in order to solve the above-described problems. As a result, it has been found that the sliding characteristics can be further improved by configuring the sliding layer with a dry lubricating film containing a polyamideimide resin having a specific structure and a solid lubricant, and the present invention is completed. It came to. That is, the present invention provides the following.

  (1) A first invention of the present invention is a dry lubricating coating composition comprising a polyamideimide resin having diphenyl ether as a residue as a binder resin, the binder resin and a solid lubricant.

  (2) The second invention of the present invention is the dry lubricating film composition according to the first invention, wherein the content of the solid lubricant is 15% by mass to 75% by mass with respect to the total solid content. .

  (3) According to a third aspect of the present invention, in the first or second aspect, the solid lubricant is selected from molybdenum disulfide, polytetrafluoroethylene, graphite, tungsten disulfide, boron nitride, and graphene. It is a dry lubricating coating composition that is one or more.

  (4) A fourth invention of the present invention is a sliding member comprising a sliding layer on the surface of a substrate, wherein the sliding layer comprises a polyamideimide resin having a residue of diphenyl ether, a solid lubricant, It is a sliding member comprised by the dry lubricating film containing this.

  (5) The fifth invention of the present invention is the sliding member according to the fourth invention, wherein the sliding layer has a sliding layer surface roughness of Ra 1.5 μm or less.

  (6) 6th invention of this invention is a sliding member whose sliding layer film thickness is 1 micrometer-30 micrometers in 4th or 5th invention.

  ADVANTAGE OF THE INVENTION According to this invention, the dry lubricating film composition which can form the sliding layer which the sliding characteristic improved more can be provided. In addition, according to the sliding member in which the sliding layer is formed on the surface of the base material by the dry lubricating film formed using the dry lubricating film composition, it is possible to stably exhibit more excellent sliding characteristics. Can do.

It is sectional drawing which shows the structure of a slide bearing. It is a graph which shows the torque measurement result about the dry lubricating film formed with the dry lubricating film composition of Examples 1-3 and Comparative Examples 1-5.

  Hereinafter, a specific embodiment of the present invention (hereinafter referred to as “the present embodiment”) will be described in detail. The present invention can be variously modified without changing the gist thereof. In addition, this invention is not limited to the following embodiment, In the range which does not change the summary of this invention, it can change suitably. In addition, in this specification, the notation “x to y” (x and y are arbitrary numerical values) means “x or more and y or less” unless otherwise specified.

<< 1. Dry lubricating coating composition >>
The dry lubricating film composition according to the present embodiment is, for example, for forming a dry lubricating film that constitutes a sliding layer in a sliding member having a sliding layer on the surface of a substrate. It is a paint for forming a dry lubricating film. In addition, as a base material which forms a sliding layer on the surface, a steel base material is mentioned, for example.

  Specifically, this dry lubricating coating composition contains a polyamideimide resin having diphenyl ether as a residue as a binder resin, and contains the binder resin and a solid lubricant. In the dry lubricating coating composition, components such as a binder resin and a solid lubricant are diluted with an organic solvent.

<1-1. Constituents>
[Binder resin]
The dry lubricating coating composition contains a polyamide resin as a binder resin. This polyamide resin is a polyamideimide resin having a residue of diphenyl ether as shown in the following chemical formula (1).

  The polyamideimide resin is a resin in which an amide bond is introduced into the main chain of the polyimide resin, and has excellent sliding characteristics. It also has excellent heat resistance, can be thermoformed, and exhibits good mechanical strength, chemical resistance, and electrical properties.

  Among these polyamide-imide resins, as shown in chemical formula (1), a polyamide-imide resin having a residue of diphenyl ether is used as a binder resin, and a solid lubricant described later is dispersed, so that torque is effective during sliding. It can be reduced to a low coefficient of friction, and more excellent sliding characteristics can be exhibited.

  Heretofore, various dry lubricating coating compositions in which a solid lubricant is dispersed using a polyamideimide resin as a binder resin have been proposed. However, compared with a composition containing such a polyamideimide resin, the present inventors have a friction coefficient of a dry lubricating film obtained by using a polyamideimide resin having a residue of diphenyl ether as a binder resin. It has been found that the torque can be effectively reduced when a sliding layer of a sliding member such as a sliding bearing is configured.

  Thus, although the mechanism which expresses the effect of the excellent low friction property by using the polyamideimide resin which makes a diphenyl ether residue as a binder resin is not certain, it estimates as follows. That is, in the polyamideimide resin having diphenyl ether as a residue, the ether bond (—C—O—C—) in the molecule of the diphenyl ether is a bond in which no adjacent hydrogen exists in the oxygen atom, so the rotational energy is small and the free rotation Therefore, it is easily elastically deformed and has flexibility. Thereby, it is estimated that the lubricating film containing this polyamideimide resin as a binder resin relieves stress due to sliding, and as a result, a low friction coefficient can be stably obtained.

  In addition, it does not specifically limit as a polyamidoimide resin which uses diphenyl ether as a residue, What is marketed can be applied effectively.

  Although it does not specifically limit as content of a polyamideimide resin, It is preferable that it is about 10 mass%-60 mass% with respect to the total solid contained in the said dry lubricating film composition, and 20 mass%-50 mass. More preferably, it is about mass%. If the content of the polyamideimide resin is less than 10% by mass relative to the total solid content, the effect of improving the slidability may not be sufficiently obtained, and the wear amount may increase. On the other hand, if it exceeds 60% by mass, the ratio (P / B) with a solid lubricant described later is relatively decreased, and the friction reduction effect may not be obtained.

  Further, as the binder resin, a polyamide resin may be further included. Polyamide resin, also called nylon, is a general term for polymers formed by amide bonds, and is synthesized mainly from various monomers including a linear aliphatic polyamide structure. In addition to linear aliphatic polyamides obtained by polymerization of lactam or aminocarboxylic acid, or polymerization of diamine and dicarboxylic acid, amorphous aromatic-containing transparent polyamides, mixtures of modified polyolefins, graft-polymerized polyamides, polyethers or Examples include polyamide elastomers having polyester as a soft segment.

  Here, in the binder resin constituting the dry lubricating coating composition, the content ratio of the structure of diphenyl ether which is a residue derived from the polyamideimide resin in the structure is such that all acid groups and residues in the structure of the binder resin. Is preferably 20% or more, more preferably 40% or more, and still more preferably 50% or more. Thus, when the content ratio of the structure of diphenyl ether derived from the polyamideimide resin in the structure of the binder resin is 20% or more, the effect of reducing torque can be exhibited more effectively, and at the time of sliding Improve the sliding characteristics in

  Regarding the content ratio of such a structure of diphenyl ether, the dry lubricant film formed using the dry lubricant film composition is sampled, and the peak area of the decomposition product obtained by thermal decomposition is determined by pyrolysis gas chromatography mass spectrometry. It can be calculated from the ratio.

  In addition, it is preferable that the upper limit of the content ratio of the structure of diphenyl ether in the structure of binder resin is 70% or less.

  Although it does not specifically limit as content of a polyamide resin, It is preferable to set it as about 1 mass%-30 mass% with respect to the total solid contained in the said dry lubricating film composition.

[Solid lubricant]
The dry lubricating coating composition contains a solid lubricant. Thus, the inclusion of the solid lubricant can reduce the coefficient of friction of the dry lubricating film to be formed, and exhibits excellent sliding characteristics. Further, non-seizure property can be improved.

The solid lubricant is not particularly limited, and examples thereof include molybdenum disulfide (MoS ₂ ), polytetrafluoroethylene (PTFE), graphite, tungsten disulfide (WS ₂ ), boron nitride (BN), and graphene. It is done. Among them, using a solid lubricant selected from molybdenum disulfide, polytetrafluoroethylene, graphite, and tungsten disulfide exhibits superior low friction properties and is excellent in chemical stability. Particularly preferred. These solid lubricants can be used alone or in combination of two or more.

  Although it does not specifically limit as content of a solid lubricant, It is preferable that it is about 15 mass%-75 mass% with respect to the total solid contained in the said dry lubricating film composition, 25 mass%-65 More preferably, it is about mass%. If the content of the solid lubricant is less than 15% by mass with respect to the total solid content, the friction reducing effect may not be sufficiently exhibited. On the other hand, if it exceeds 75% by mass, the amount of wear of the dry lubricating film to be formed increases, and there is a possibility that excellent wear resistance may not be exhibited.

  The content ratio (P / B) of the binder resin (B) and the solid lubricant (P) described above is preferably in the range of 0.5 to 5.0, and preferably 1.0 to 4.5. Is more preferable, and the range of 1.5 to 3.5 is particularly preferable. In addition, a content ratio means the value of mass ratio of binder resin (B) and solid lubricant (P).

[Organic solvent]
The organic solvent is, for example, for dissolving the binder resin. Although it does not specifically limit as an organic solvent, It is preferable to select in consideration of the solubility with respect to the binder resin to be used, drying property, etc. Specific examples include organic solvents such as N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, and cyclopentanone. An organic solvent can be used individually by 1 type or in combination of 2 or more types.

[Others]
In addition, in a dry lubricating film composition, various additive components can be contained as needed. Specifically, for example, additives such as a filler, an anti-settling agent, a wetting and dispersing agent, an antifoaming agent, and a surface conditioner can be used.

  Examples of fillers include calcium fluoride, calcium carbonate, talc, mica, mullite, calcium phosphate, iron oxide, aluminum oxide, chromium oxide, cerium oxide, zirconium oxide, titanium oxide, silicon oxide, magnesium oxide and other oxides, molybdenum Examples thereof include carbides, carbides such as silicon carbide, aluminum nitride, silicon nitride, boron nitride (cubic boron nitride), and diamond. These fillers can be used alone or in combination of two or more.

  Further, as the binder resin, the above-described polyamide-imide resin may contain other resins such as a thermoplastic resin such as a polyamide resin or a polyimide resin.

<1-2. Method for producing dry lubricating coating composition>
It does not specifically limit as a manufacturing method of the dry lubricating film composition which concerns on this Embodiment, It can manufacture by a conventionally well-known method.

  Specifically, it is produced by blending and kneading a binder resin (containing a polyamide-imide resin) that is a solid component, a solid lubricant, and an organic solvent that is a volatile component in a predetermined ratio. Can do. At this time, it is important that the solid lubricant is uniformly dispersed in the binder resin uniformly dissolved in the organic solvent.

  For example, as a method for producing this dry lubricating film composition, first, a predetermined amount of each component is weighed, then, an organic solvent is charged into a stirring vessel, and then a binder resin and a solid lubricant are charged, Stir with a stirrer such as a dissolver type stirrer or a ball mill until these materials are uniformly dissolved. Then, the dispersion process which disperse | distributes a solid lubricant uniformly in binder resin is implemented using dispersers, such as a sand mill type and a three roll type. In addition, it is good also as a composition by diluting by adding an organic solvent after dispersion | distribution.

≪2. Sliding member >>
FIG. 1 is a cross-sectional view showing a configuration of a slide bearing which is a sliding member according to the present embodiment. As shown in FIG. 1, the plain bearing 1 has a configuration in which a sliding layer 12 is provided on the surface of a base material 11 made of, for example, a copper-based alloy or an aluminum-based alloy joined to the surface of a back metal 13. have.

  For example, a substrate having a Vickers hardness of 30 or more as measured with a micro Vickers hardness meter can be used as the substrate 11 made of a copper alloy, an aluminum alloy, or the like.

  The sliding bearing 1 is characterized in that the sliding layer 12 is composed of a dry lubricating film containing a polyamideimide resin having diphenyl ether as a residue and a solid lubricant. In such a sliding bearing 1, the torque is effectively reduced as compared with the conventional one, showing low frictional properties, and exhibiting excellent sliding characteristics in the sliding layer 12.

  Here, in the sliding layer 12, when the surface roughness of the sliding layer is rough, the oil film is easily cut, and the surface of the sliding layer and the mating shaft are easily in contact with each other, and seizure occurs due to heat generated by friction. It becomes easy. For this reason, the surface roughness of the sliding layer is preferably Ra 1.5 μm or less. When the surface roughness of the sliding layer is Ra 1.5 μm or less, oil is easily supplied to the surface of the sliding layer to form an oil film, and seizure hardly occurs. Further, the sliding layer surface roughness is more preferably Ra 1.0 μm or less, and further preferably Ra 0.5 μm or less.

  Moreover, in the sliding layer 12, it is preferable that the sliding layer film thickness is 1 micrometer-30 micrometers. For example, a local contact between the sliding layer and the mating shaft is likely to occur under conditions where the sliding mating shaft is bent or vibrated, such as a bearing for an internal combustion engine. At this time, the sliding layer is plastically deformed, elastically deformed, or worn at the contact point, so that the local load increase is alleviated, and the material of the sliding layer is not lowered by heat generation, and seizure occurs. It becomes difficult to do. From the viewpoint of alleviating such a local load increase, the thickness of the sliding layer 12 is preferably 1 μm to 30 μm.

Moreover, in the sliding layer 12, a hard particle, a soft metal particle, etc. can be further contained as needed. Examples of the hard particles include nitrides such as silicon nitride (Si ₃ N ₄ ), oxides such as aluminum oxide (Al ₂ O ₃ ), silicon oxide (SiO ₂ ), and titanium oxide (TiO ₂ ), silicon carbide (SiC) ) And the like can be used. Moreover, copper, silver, gold | metal | money, aluminum, tin, zinc, bismuth etc., these alloys etc. can be used as a soft metal particle.

  The sliding layer 12 can be configured by applying the above-described dry lubricating coating composition on the surface of the substrate 11 to form a dry lubricating coating. The method for applying the dry lubricating coating composition is not particularly limited, and for example, it can be performed by air spray application. Moreover, you may make it carry out by methods, such as dip (dipping) application | coating, brush coating, tumbling by spraying, and screen printing. Selection of these coating methods can be appropriately determined according to the surface shape of the substrate 11 and the like.

  Thus, after apply | coating a dry lubricating film composition to the surface of the base material 11, after giving a drying process and baking at the temperature of about 150 to 300 degreeC, the sliding layer 12 comprised with a dry lubricating film is formed. Can be formed. Prior to applying the dry lubricating coating composition to the substrate 11, a degreasing treatment, a surface treatment for improving the adhesion of the dry lubricating coating, a cleaning treatment, or the like can be performed.

  EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples.

<< Examples and Comparative Examples >>
[Example 1]
(Preparation of dry lubricating coating composition)
Polyamideimide resin (PAI) (described as “PAI [1]” for distinction) and polyamide resin (PA) having a residue of diphenyl ether as a binder resin and molybdenum disulfide as a solid lubricant Using calcium carbonate as a pigment, each is weighed as shown in Table 1 below, put into a ball mill together with an organic solvent, and mixed and stirred, whereby a dry lubricating coating composition in which a solid lubricant is dispersed in a binder resin (dry lubricating) A coating-forming coating material) was prepared. As the organic solvent, N-methyl-2-pyrrolidone and a solvent (xylol, Sankyo Chemical Co., Ltd.) containing xylene and ethylbenzene in a ratio of 40:60 were used.

(Production of slide bearing)
Next, a copper-based bearing metal layer was joined onto a steel plate serving as a back metal, and after processing this into a cylindrical shape, a degreasing treatment was performed, and then the surface of the bearing metal layer was roughened by blasting. Further, after pickling, hot water washing and drying, the prepared coating material for forming a dry lubricating film was sprayed onto the surface of the bearing metal layer by air spraying. Then, the organic solvent contained in the composition was removed by drying and baked at 240 ° C. for 30 minutes. As a result, a sliding layer composed of a dry lubricating film was formed on the surface of the bearing metal layer. The thickness of the sliding layer (sliding layer thickness) was set to 10 μm.

[Example 2]
In Example 2, as shown in Table 1 below, the dry lubricating film was the same as Example 1 except that the ratio (P / B) of the binder resin (B) and the solid lubricant (P) was changed. A composition was prepared. Similarly, a plain bearing having a sliding layer formed by applying the dry lubricating coating composition was produced.

[Example 3]
In Example 3, as shown in Table 1 below, the same procedure as in Example 1 was used except that the binder resin was composed only of a polyamideimide resin (PAI [1]) having diphenyl ether as a residue. Thus, a dry lubricating coating composition was prepared. Similarly, a plain bearing having a sliding layer formed by applying the dry lubricating coating composition was produced.

[Comparative Example 1]
In Comparative Example 1, as shown in Table 1 below, the binder resin is composed of a polyamideimide resin having a residue of diphenylmethane (described as “PAI [2]” for distinction) and a polyamide resin. A dry lubricating coating composition was prepared in the same manner as in Example 1 except that it was used. Similarly, a plain bearing having a sliding layer formed by applying the dry lubricating coating composition was produced.

[Comparative Example 2]
In Comparative Example 2, as shown in Table 1 below, Examples were used except that a binder resin composed of a polyamideimide resin having a residue of diphenylmethane and a polyamide resin (PAI [2]) was used. In the same manner as in No. 2, a dry lubricating coating composition was prepared. Similarly, a plain bearing having a sliding layer formed by applying the dry lubricating coating composition was produced.

[Comparative Example 3]
In Comparative Example 3, as shown in Table 1 below, the binder resin is composed of a polyamideimide resin having a residue of diphenylmethane and a polyamide resin (described as “PAI [3]” for distinction). A dry lubricating coating composition was prepared in the same manner as in Example 2 except that it was used. Similarly, a plain bearing having a sliding layer formed by applying the dry lubricating coating composition was produced.

[Comparative Example 4]
In Comparative Example 4, as shown in Table 1 below, the binder resin is the same as Example 3 except that the binder resin is composed only of polyamideimide resin (PAI [2]) having diphenylmethane as a residue. Thus, a dry lubricating coating composition was prepared. Similarly, a plain bearing having a sliding layer formed by applying the dry lubricating coating composition was produced.

[Comparative Example 5]
In Comparative Example 5, as shown in Table 1 below, the binder resin is the same as Example 3 except that the binder resin is composed only of polyamideimide resin (PAI [3]) having diphenylmethane as a residue. Thus, a dry lubricating coating composition was prepared. Similarly, a plain bearing having a sliding layer formed by applying the dry lubricating coating composition was produced.

[Evaluation]
(Torque measurement)
A torque measurement test using a torque tester was performed on each of the slide bearings of Examples 1 to 3 and Comparative Examples 1 to 5. The test conditions are as follows.
Rotation speed: 70rpm, 700rpm
Test surface pressure: 10 MPa
Test time: 6 hours Lubricating oil type: VG22
Lubricating oil flow rate: 200cc / min
Lubricating oil temperature: 80 ° C
Shaft material: S55C

(Hardness measurement)
The hardness of the dry lubricating film by the dry lubricating film composition prepared in each of Examples 1 to 3 and Comparative Examples 1 to 5 was measured using a dynamic ultra-micro hardness meter (DUH-211S, manufactured by Shimadzu Corporation). . The test conditions are as follows.
Test mode: Load / unloading test Maximum load: 1.5mN
Load holding time: 10 seconds Unloading holding time: 5 seconds

[result]
In the following Table 1, the composition of the dry lubricating coating composition prepared in each of Examples 1 to 3 and Comparative Examples 1 to 5, and the results of torque measurement and hardness measurement of the formed dry lubricating coating are shown together. FIG. 2 is a graph showing the results of torque measurement at rotation speeds of 70 rpm and 700 rpm in each example and comparative example. The torque measurement at a rotation speed of 700 rpm is performed on the dry lubricating coatings of Examples 1 to 3 and Comparative Example 1, and is not performed (−) in Comparative Examples 2 to 5.

  As shown in the results of Table 1 and FIG. 2, in the torque measurement at a rotation speed of 700 rpm and 70 rpm, in the sliding layers of Examples 1 to 3 using a binder resin containing a polyamideimide resin having diphenyl ether as a residue, Torque value was effectively reduced and low friction was exhibited.

  According to the results of hardness measurement, it was found that the hardness of the sliding layers of Examples 1 to 3 using a binder resin containing a polyamideimide resin having diphenyl ether as a residue was relatively low.

≪Evaluation by pyrolysis gas chromatography mass spectrometry≫
Mass spectrometry was performed by pyrolysis gas chromatograph on the coatings of the dry lubricating coating compositions prepared in Examples 2 and 3 and Comparative Examples 2 and 3 described above.

  Specifically, a dry lubricating coating composition is air sprayed onto a cold-rolled steel sheet (SPCC-SB) of 150 mm × 100 mm × 0.8 mm as a base material so that the dry film thickness is about 10 μm. And sprayed on. Thereafter, the organic solvent contained in the composition was removed by drying and baked at 240 ° C. for 30 minutes to form a dry lubricating film on the substrate.

  Next, the dry lubricant film was scraped with a spoon and sampled, and the film piece (0.5 mg) was wrapped in a pile foil, set in a Curie point injector, and rapidly heated to 670 ° C. to collect decomposition gas. . Then, the decomposition gas was introduced into a gas chromatograph (gas chromatograph mass spectrometer: GC-MS) equipped with a mass spectrometer (MS). As temperature conditions, the temperature was raised to 50 ° C. to 320 ° C. (10 ° C./min) and held at 320 ° C. for 13 minutes for component detection. As a gas chromatograph apparatus, 6890A manufactured by Agilent Technologies is used for the GC oven, 5973N manufactured by Agilent Technologies is used for the mass spectrometer, and JCI-22 manufactured by Nippon Analytical Industries, Ltd. is used for the thermal decomposition apparatus. It was used.

  As a result of analysis, the peaks of the decomposition products obtained differed depending on the type of the skeleton structure of the polyamideimide resin contained as the binder resin (diphenyl ether, diphenylmethane). Therefore, from the results of thermal analysis of each example and comparative example, residues (diphenyl ether, diphenylethane) and acid groups (N-phenylphthalimide, N- (4-methylphenyl) phthalimide) in the skeleton structure of the polyamideimide resin The peak area of each degradation product was determined, and the peak area ratio (ratio of the residue and acid group to all peak areas) of the residue of the polyamideimide resin (residue degradation product: diisocyanate degradation product) was calculated. Table 2 below shows the structural formulas of the decomposition products and the measurement results of the respective peak areas in each Example and Comparative Example. Table 2 also shows the results of torque measurement (70 rpm) of the dry lubricating coating.

  As Reference Examples 1 to 4, a dry lubricating coating composition was prepared using a binder resin in which the content ratio of the diphenyl ether structure as a residue was adjusted, and the dry lubricating coating by the composition was similarly subjected to pyrolysis gas chromatograph. A graph mass analysis was performed to calculate a peak area ratio of the decomposition product, and a torque measurement (70 rpm) of the dry lubricating coating was performed.

  As a result of GC-MS analysis, from the dry lubricating coatings of Examples 2 and 3, diphenyl ether as a residue constituting polyamideimide resin as a binder resin and N-phenylphthalimide as an acid group were detected as decomposition products. It was done. On the other hand, from the dry lubricating film of Comparative Examples 2 and 3, as decomposition products, diphenylmethane which is a residue constituting polyamideimide resin which is a binder resin, N-phenylphthalimide and N- (4- Methylphenyl) phthalimide was detected.

  From the results regarding this GC-MS analysis and the results shown in Table 1, it is presumed that the expression of the torque reduction effect of the sliding layer on which the dry lubricating film is formed is derived from the difference in the structure of the binder resin residue. be able to. That is, it has been found that the structure of diphenyl ether derived from the binder resin expresses a low torque value and effectively reduces the friction coefficient.

  In addition, from the results of Reference Examples 1 to 4, preferably, the dry lubricating film composition using a binder resin having a diphenyl ether structure content ratio of approximately 20% or more has a more effective torque value of the dry lubricating film. It has been found that the sliding properties are further reduced and exhibit even better sliding characteristics.

≪Evaluation of contact angle≫
Using the dry lubricating coating composition prepared in each of Examples 2 and 3 and Comparative Examples 2 and 3 described above, on a cold rolled steel sheet (SPCC-SB) of 150 mm × 100 mm × 0.8 mm as a base material, Application was performed by spraying with air spray so that the film thickness in the dry state was about 10 μm. Thereafter, the organic solvent contained in the composition was removed by drying and baked at 240 ° C. for 30 minutes to form a dry lubricating film on the substrate to prepare a test piece.

  Using the prepared test piece, the static contact angle with mineral oil (Super Oil B-100, manufactured by JXTG Energy) was measured by the droplet method. The contact angle was measured using a contact angle meter (DMs-401, manufactured by Kyowa Interface Science Co., Ltd.). Table 3 below shows the measurement results (average of five measurement values (n = 5)).

  As shown in Table 3, the dry lubricating film according to Examples 2 and 3 using a binder resin containing a polyamideimide resin having diphenyl ether as a residue has a smaller contact angle to oil than Comparative Examples 2 and 3. It was recognized that In other words, it was found that the dry lubricating coatings produced in Examples 2 and 3 have high compatibility with oil. From the results regarding this contact angle evaluation and the results shown in Table 1, the coating with a dry lubricating coating composition using a binder resin containing a polyamideimide resin having diphenyl ether as a residue is highly compatible with oil. It can be inferred that low torque could be developed.

11 Substrate 12 Sliding layer 13 Back metal

Claims (6)

A dry lubricating coating composition comprising a polyamideimide resin having a residue of diphenyl ether as a binder resin, the binder resin and a solid lubricant. The dry lubricant film composition according to claim 1, wherein a content of the solid lubricant is 15% by mass to 75% by mass with respect to a total solid content. The dry lubricating coating composition according to claim 1 or 2, wherein the solid lubricant is at least one selected from molybdenum disulfide, polytetrafluoroethylene, graphite, tungsten disulfide, boron nitride, and graphene. A sliding member comprising a sliding layer on the surface of the substrate,
The sliding layer is composed of a dry lubricating film containing a polyamideimide resin having diphenyl ether as a residue and a solid lubricant. The sliding member according to claim 4, wherein the sliding layer has a sliding layer surface roughness of Ra 1.5 μm or less. The sliding member according to claim 4, wherein the sliding layer has a sliding layer thickness of 1 μm to 30 μm.

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