Resin composition and sliding member

Abstract

The present invention relates to a resin composition and a sliding member, the resin composition consisting of a binder resin made using a thermosetting resin and an additive dispersed in the binder resin. The additive is prepared from polytetrafluoroethylene (PTFE), graphite and optional MoS2. The average particle size of each additive is less than 10 [mu] m. The average particle size of the PTFE is larger than that of the graphite and the MoS2, and the volume content of the PTFE is higher than that of the MoS2.

Description

[0001] This application is a divisional application of PCT international application PCT / JP2017 / 041336, whose application date is November 16, 2017. The original application is an invention patent application. The application number entering the Chinese national phase is 201780069675.3, and the name is "Resin composition and sliding parts". Technical Field

[0002] The present invention relates to sliding components. Background Art

[0003] In order to improve the characteristics of the sliding surface, a sliding material having a resin coating is known in which PTFE, graphite, and MoS 2 are used as additives in a binder resin (refer to Patent Documents 1 and 2).

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2002-310345

[0007] Patent Document 2: Japanese Patent Application Publication No. 2008-56750 Summary of the invention

[0008] Technical issues

[0009] In the technology disclosed in Patent Document 1 or 2, there is a problem that the solid lubricant falls off or cracks under a high load state, and as a result, the sliding surface becomes rougher. When the sliding surface becomes rough, the formation of the oil film is hindered, especially in a low amount of oil or dry environment due to insufficient supply of lubricating oil. In this case, the seizure resistance and wear resistance are reduced.

[0010] The present invention provides a technique for improving anti-seizure and anti-wear properties under high load conditions in an environment where lubricating oil supply is insufficient.

[0011] Technical Solution

[0012] The present invention provides a resin composition, which comprises: a binder resin made of a thermosetting resin; an additive dispersed in the binder resin, wherein the additive comprises PTFE (polytetrafluoroethylene), and at least one of graphite and MoS2, wherein the average particle size of each of the additives is less than 10 μm, and the average particle size of PTFE is larger than the average particle size of graphite and MoS2.

[0013] The binder resin may include at least one of polyamide-imide and polyimide.

[0014] The binder resin may be polyamide-imide.

[0015] The binder resin may be included in an amount of 50 volume % to 80 volume %.

[0016] The content of PTFE is higher than that of MoS2.

[0017] The content of MoS2 is 0 volume % to 10 volume %.

[0018] The additive may comprise hard particles.

[0019] The present invention also provides a sliding component, comprising: a substrate; and a coating layer made of the resin composition.

[0020] Beneficial effects

[0021] According to the present invention, it is possible to improve anti-seizure and anti-wear properties under high load conditions in an environment where lubricating oil supply is insufficient. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 1 is a schematic cross-sectional view showing the structure of a compressor 1 according to one embodiment.

[0023] Figure 2 An example of the positional relationship between the swash plate 3 and the slider 5 is described.

[0024] Figure 3 An exemplary cross-sectional structure of the swash plate 3 is described.

[0025] Figure 4 Shown is the surface pressure measured in the contact resistance test.

[0026] Figure 5 The status of the sliding surface before and after the sliding test is shown.

[0027] Reference numerals list

[0028] 1: compressor, 2: shaft, 3: swash plate, 31: base material, 32: coating, 33: coating, 4: piston DETAILED DESCRIPTION

[0029] 1. Construction

[0030] Figure 1: is a schematic cross-sectional view showing the structure of a compressor 1 of one embodiment of the present invention. The compressor 1 is a so-called swash plate type compressor. The compressor 1 includes a shaft 2, a swash plate 3, a piston 4, and a slider 5. The shaft 2 is supported in a rotatable manner relative to a housing (not shown in the figure). The swash plate 3 is fixed at a certain inclination angle relative to the rotation axis of the shaft 2. The swash plate 3 is an example of a sliding component of the present invention. The piston 4 reciprocates in a cylinder bore (not shown in the figure) provided in the housing. The slider 5 is provided between the swash plate 3 and the piston 4, and slides with the swash plate 3 and the piston 4, respectively. In the slider 5, the surface sliding with the swash plate 3 is substantially flat, while the surface sliding with the piston 4 has a dome-like (hemispherical) shape. The slider 5 is an example of a mating component sliding on the sliding component of the present invention. The swash plate 3 converts the rotation of the shaft 2 into the reciprocating motion of the piston 4.

[0031] Figure 2 An example of the positional relationship between the swash plate 3 and the slider 5 is described. Figure 2 is a view perpendicular to the direction of the sliding surface. The swash plate 3 is in the shape of a circular disk as a whole, with a hole in the center of the disk. When viewed from the swash plate 3, the slider 5 performs a rotational motion on the sliding surface. Here, "rotational motion" refers to a motion in which the slider 5 defines a circular trajectory relative to the swash plate 3.

[0032] Figure 3 A schematic cross-sectional structure of the swash plate 3 is described. Figure 3 3 is a schematic diagram showing a structure in a cross section perpendicular to the surface that slides with the slider 5. The swash plate 3 has a substrate 31, a coating 32, and a coating 33. Both the coating 32 and the coating 33 slide on the slider 5. Both the coating 32 and the coating 33 are examples of the coating of the present invention. The substrate 31 is formed into a disk shape having a hole in the center. The substrate is made of an alloy that satisfies the required characteristics, for example, the material is an iron-based alloy, a copper-based alloy, or an aluminum-based alloy. From the viewpoint of preventing adhesion to the slider 5, the swash plate 3 is preferably made of a material different from that of the slider 5.

[0033] The coating 32 is formed to improve the characteristics of the sliding surface of the swash plate 3. The coating 32 is made of a resin composition. The resin composition includes a binder resin and an additive dispersed in the binder resin. The binder resin is, for example, made of a thermosetting resin. For example, at least one of polyamideimide (PAI), polyamide (PA) and polyimide (PI), epoxy resin and phenol can be used as the thermosetting resin. Among them, the binder resin preferably includes at least one of PAI and PI. For example, the content of the binder resin in the resin composition is preferably 50 volume % to 80 volume %. More preferably, the content of the binder resin is greater than 60 volume %. More preferably, the upper limit of the content of the binder resin is 75 volume %.

[0034] Solid lubricant is used as additive.Solid lubricant is added to improve lubrication properties, in other words, to reduce friction coefficient.For example, resin combination comprises a total of 20 volume % to 50 volume % of solid lubricant.PTFE (polytetrafluoroethylene) is used as solid lubricant.In addition, in addition to PTFE, the resin combination also comprises graphite (Gr) and MoS2 at least one.The content of MoS2 is preferably less than the content of PTFE.For example, the content of PTFE is 10 volume % to 30 volume %, more preferably 15 volume % to 25 volume %.The content of MoS2 is 0 volume % to 10 volume %, preferably 0 volume % to 4 volume % (that is, MoS2 may not be included).The content of graphite is preferably 0 volume % to 20 volume %, more preferably 10 volume % to 20 volume %.In addition, it is preferred that MoS2 content is less than the content of graphite.

[0035] In order to improve the smoothness of the sliding surface and assist in the formation of the oil film, the average particle size of the additive added to the binder resin is preferably less than 10 μm, more preferably equal to or less than 5 μm. Here, the average particle size refers to the 50% diameter (median diameter) in the distribution of spherical equivalent diameters obtained by laser diffraction method in the state of the raw material before mixing with the binder resin. When the average particle size of the additive is less than 10 μm, the sliding surface can be kept smooth, and the formation of the oil film is thereby promoted, in contrast to the case where the average particle size of the additive is equal to or less than 10 μm. Therefore, the transition from boundary lubrication to mixed lubrication or fluid lubrication is promoted, and enhanced lubrication is easily obtained even under harsh conditions such as low oil content and high load.

[0036] The average particle size of PTFE is preferably larger than that of graphite or that of MoS2. The inventors of the present invention assume that by using PTFE having an average particle size larger than that of graphite and MoS2, PTFE is stretched on the sliding surface to cover graphite or MoS2, thereby making it easy to maintain the smoothness of the sliding surface.

[0037] The resin composition may further contain hard particles as an additive. As the hard particles, for example, at least one of oxides, nitrides, carbides and sulfides is used. The average particle size of the hard particles is preferably less than 10 μm, more preferably less than the average particle size of PTFE.

[0038] The coating layer 33 is also formed using the same resin composition as the coating layer 32. In the substrate 31, the surface serving as the sliding surface, that is, the surface on which the coating layer 32 is formed and the surface on which the coating layer 33 is formed, are substantially flat. The surface of the substrate 31 may be roughened to enhance adhesion with the coating layer 32. In addition, an intermediate layer may be formed between the substrate 31 and the coating layer 32.

[0039] The present invention is not limited to the above embodiment, and various modifications can be applied to the embodiment. For example, the sliding part having a coating formed using the resin composition of the present embodiment is not limited to a swash plate for a compressor. The sliding part may be a slider for a compressor, or a half bearing, a bushing, or a thrust washer used in an engine.

[0040] 2. Experimental Examples

[0041] The inventors manufactured test pieces of sliding parts under various conditions. The inventors evaluated their characteristics. Cast iron was used as the base material of the sliding part. The base material was processed into Figure 1 The slanted disc shape shown in . A coating layer was formed on the prepared substrate, the coating layer being made of the resin composition described in Table 1. PAI was used as a binder resin. In addition, Experimental Example 3 is an example in which the average particle size of MoS2 is larger than the average particle size of PTFE.

[0042] [Table 1]

[0043]

[0044] First, the wear resistance test was performed on the test pieces of the above three experimental examples. The test conditions of the wear resistance test are as follows.

[0045] Test device: High pressure atmospheric friction and wear tester

[0046] Speed: 40m / s

[0047] Surface pressure: 4 to 12 MPa (increase: 2 MPa / 3 minutes)

[0048] Time: 1 hour at maximum surface pressure

[0049] Atmosphere: Refrigerant and poor lubrication

[0050] Corresponding material: bearing steel

[0051] The inventors observed the sliding surface of the test piece after the test and determined whether the coating was worn. Although wear occurred in Experimental Example 3, no wear was found in Experimental Examples 1 and 2. That is, Experimental Examples 1 and 2 had improved wear resistance compared to Experimental Example 3.

[0052] Furthermore, the present inventors conducted a seizure resistance test on the test pieces of Experimental Examples 1 and 2. The test conditions of the seizure resistance test were as follows.

[0053] Test device: Oil injection poor lubrication test machine

[0054] Speed: 6.3m / s

[0055] Surface pressure: 2 to 20 MPa (increase: 2 MPa / min)

[0056] Time: Up to 10 minutes

[0057] Lubrication method: spray

[0058] Lubricating oil: Refrigeration oil

[0059] Corresponding material: bearing steel

[0060] Figure 4 The surface pressure measured in the contact resistance test is shown. Although the test piece of Experimental Example 3 seizures at a surface pressure of 10 MPa, the test pieces of Experimental Examples 1 and 2 do not seizure even at the maximum surface pressure of the test device of 20 MPa. Therefore, Experimental Examples 1 and 2 have improved seizure resistance compared to Experimental Example 3.

[0061] In addition, the inventors conducted a sliding test on the test pieces of Experimental Examples 1 and 2, and measured the surface roughness of the sliding surface using a surface roughness meter (SP81B manufactured by Kosaka Laboratory) before and after the test. In addition, the surface was observed with an electron microscope. The test conditions of the sliding test were the same as those of the above-mentioned anti-seizure test.

[0062] Figure 5 The status of the sliding surface before and after the sliding test is shown. Figure 5 (A) shows Experimental Example 1, Figure 5 (B) shows Experimental Example 2, Figure 5 (C) shows Experimental Example 3. It should be noted that the surface roughness is measured as the ten-point average roughness RzJIS defined in JIS B 0601:2001. Although the surface roughness increased in Experimental Example 3 during the sliding test, the surface roughness decreased in Experimental Examples 1 and 2 during the sliding test. In other words, although the surface of Experimental Example 3 became rougher after use, the surfaces of Experimental Examples 1 and 2 became smoother after use.

Claims

1. A resin composition, comprising the following components: 50% to 80% by volume of a binder resin made of a thermosetting resin, the binder resin comprising polyamide-imide; additives dispersed in the binder resin, in, The additive consists of the following ingredients: 10% to 30% by volume of PTFE (polytetrafluoroethylene), 10 to 20 volume % of graphite, and 0 vol% to 4 vol% MoS2, The average particle size of each of the additives is less than 10 μm, The average particle size of PTFE is larger than that of graphite and MoS2, and The volume content of PTFE is higher than that of MoS2.

2. The resin composition according to claim 1, wherein The binder resin further includes polyimide.

3. The resin composition according to claim 1, wherein The binder resin is polyamide-imide.

4. A sliding component, comprising: Base material; and A coating layer, wherein the coating layer is made of the resin composition according to any one of claims 1 to 3.

Images