LUBRICATING COATING COMPOSITION AND COMPRESSOR INCLUDING THE SAME

Abstract

A lubricating coating composition and a compressor including a sliding member coated with the lubricating coating composition. The lubricating coating composition includes a thermosetting or thermoplastic polyimide-based resin as a binder, a solid lubricant, various solvents, and other additives at a controlled ratio. The compressor includes a first member including a first sliding surface and a second member moving relative to the first member including a second sliding surface. The lubricating coating composition is applied to the first sliding surface or the second sliding surface.

Claims

1. A compressor comprising: a first sliding surface of a first member; a second sliding surface of a second member, the first sliding surface and the second sliding surface move relative to each other; and a lubricating coating composition coated on any one of the first sliding surface and the second sliding surface to form a lubricating layer, wherein the lubricating coating composition further comprises: a polyimide-based resin; a solid lubricant; a filler; a silane coupling agent; and a solvent, wherein based on a total weight of the lubricating coating composition, 10-24 wt % of the polyimide-based resin, 6-10 wt % of the solid lubricant, 1-2.5 wt % of the filler, 0.1-2.4 wt % of the silane coupling agent, and 60-80 wt % of the solvent, wherein the polyimide-based resin is polyamide imide, wherein the solid lubricant is polytetrafluoroethylene (PTFE), wherein the filler is alumina (Al.sub.2O.sub.3), and wherein the solvent is consisting of N-methyl-2-pyrrolidone (NMP), xylene, dimethylacetamide (DMAC), and methyl ethyl ketone (MEK), wherein the lubricating coating composition has a viscosity of 30-40 cP.

2. The compressor of claim 1, wherein the polyimide-based resin and the solid lubricant are present at a weight ratio of 1.6:1 to 3:1.

3. The compressor of claim 1, wherein the polytetrafluoroethylene (PTFE) has an average particle diameter of 0.1-1 m.

4. The compressor of claim 1, wherein the filler has an average particle diameter of more than 0 and 2 m or less.

5. The compressor of claim 1, wherein the silane coupling agent is selected from a group consisting of aminophenyltrimethoxysilane (C.sub.9H.sub.15NO.sub.3Si), N-(2-aminoethyl)-3-aminopropyl trimethoxysilane (C.sub.8H.sub.22N.sub.2O.sub.3Si), bis(triethoxypropyl)amine (C.sub.18H.sub.43NO.sub.6Si.sub.2), (chloromethyl)phenylethyl trimethoxysilane (C.sub.12H.sub.19ClO.sub.3Si), and Pt(0)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane.

6. The compressor of claim 1, wherein the solvent comprises N-methyl-2-pyrrolidone (NMP) and dimethylacetamide (DMAC) at a weight ratio of 2.5:1 to 4:1.

Description

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS OF THE INVENTION

[0020] Hereinafter, the present invention will be described in further detail with reference to examples. It will be obvious to those skilled in the art that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention.

Example 1: Preparation of Lubricating Coating Composition

Preparation Example 1

[0021] A lubricating coating composition comprising, based on the total weight of the composition, 16 wt % of PAI, 10 wt % of PTFE, 0.5 wt % of a silane coupling agent, 1.5 wt % of carbon black, 1.0 wt % of alumina (Al.sub.2O.sub.3) and 71 wt % of a solvent, was prepared. The solvent comprises, based on the total weight of the composition, 27 wt % of NMP, 9 wt % of xylene, 20 wt % of MEK and 15 wt % of DMAC. The lubricating coating composition was coated on a surface of a swash plate having a high surface roughness to a thickness of 8-25 m, after which it was dried at 80 C. to 120 for 1 hour or more, and then calcined at 200 C. to 300 C. for 40-120 minutes, and the calcined substrate was cooled at a temperature between 20 C. and 30 C. for 3 hours or more.

Preparation Example 2

[0022] A lubricating coating composition was prepared in the same manner as described in Preparation Example 1, except that the composition comprises, based on the total weight of the composition, 19 wt % of PAI, 7 wt % of PTFE, 1 wt % of carbon black, 1.5 wt % of alumina (Al.sub.2O.sub.3) and 66 wt % of a solvent, and the solvent comprises 10 wt % of DMAC.

Preparation Example 3

[0023] A lubricating coating composition was prepared in the same manner as described in Preparation Example 1, except that the composition comprises, based on the total weight of the composition, 6 wt % of PTFE, 0.5 wt % of carbon black and 81 wt % of a solvent, and the solvent comprises 37 wt % of NMP and 10 wt % of DMAC.

Preparation Example 4

[0024] A lubricating coating composition was prepared in the same manner as described in Preparation Example 1, except that the composition comprises, based on the total weight of the composition, 8 wt % of PTFE, 0.5 wt % of carbon black, 0.5 wt % of alumina (Al.sub.2O.sub.3) and 81.5 wt % of a solvent, and the solvent comprises 37.5 wt % of NMP and 10 wt % of DMAC.

Comparative Example 1

[0025] A lubricating coating composition was prepared in the same manner as described in Preparation Example 1, except that the composition comprises, based on the total weight of the composition, 25 wt % of PAI, 15 wt % of PTFE, 2.5 wt % of a silane coupling agent, 2.5 wt % of carbon black, 2.0 wt % of alumina (Al.sub.2O.sub.3) and 53 wt % of a solvent, and the solvent comprises 24 wt % of NMP, 5 wt % of xylene, 17 wt % of MEK and 7 wt % of DMAC.

Comparative Example 2

[0026] A lubricating coating composition was prepared in the same manner as described in Preparation Example 1, except that the composition comprises, based on the total weight of the composition, 30 wt % of PAI, 13 wt % of PTFE, 2.5 wt % of a silane coupling agent, 2.5 wt % of carbon black, 2.0 wt % of alumina (Al.sub.2O.sub.3) and 50 wt % of a solvent, and the solvent comprises 20 wt % of NMP, 7 wt % of xylene, 15 wt % of MEK and 8 wt % of DMAC.

Comparative Example 3

[0027] A lubricating coating composition was prepared in the same manner as described in Preparation Example 1, except that the composition comprises, based on the total weight of the composition, 35 wt % of PAI, 10 wt % of PTFE, 2.5 wt % of a silane coupling agent, 2.5 wt % of carbon black, 2.0 wt % of alumina (Al.sub.2O.sub.3) and 48 wt % of a solvent, and the solvent comprises 18 wt % of NMP, 8 wt % of xylene, 12 wt % of MEK and 10 wt % of DMAC.

Example 2: Comparison of Properties of Lubricating Coating Compositions

[0028] The properties of the lubricating coating compositions, prepared in Preparation Examples 1 to 4 and Comparative Examples 1 to 3, and compressors comprising the lubricating coating compositions, were compared.

TABLE-US-00001 TABLE 1 (solid content: 20-30 wt %; viscosity: 30-40 cP at 25 C.) Solid lubricant + other additives Binder Pt- Solvent Friction ML RL PAI PTFE sil C Al.sub.2O.sub.3 NMP Xylene MEK DMAC coefficient (min) (kgf) Preparation 16 10 0.5 1.5 1.0 27 9 20 15 0.05 10 1,300 Example 1 Preparation 19 7 0.5 1 1.5 27 9 20 10 0.03 11 1,800 Example 2 Preparation 16 6 0.5 0.5 1.0 37 9 20 10 0.03 15 1,800 Example 3 Preparation 16 8 0.5 0.5 0.5 37.5 9 20 10 0.03 12 1,850 Example 4 Comparative 25 15 2.5 2.5 2.0 24 5 17 7 0.02 6 1,300 Example 1 Comparative 30 13 2.5 2.5 2.0 20 7 15 8 0.02 6 1,200 Example 2 Comparative 35 10 2.5 2.5 2.0 18 8 12 10 0.02 3 1,250 Example 3

[0029] An ML test is an abrasion durability test in which the swash plate is optionally operated from a normal state in which lubricating oil is fed to the swash plate to an abnormal state in which lubricating oil is absent, and the extent to which the swash plate resists this state is measured. In the ML test, when the swash plate is operated for 7 minutes or more under the conditions of stage 6 (2,300 rpm, 200 kgf load, and lubrication-free state) of a seizure test ML standard table of Table 2 below, which are the worst expected conditions that can occur during the use of the swash plate, the swash plate is determined to satisfy the standard.

[0030] An RL test is a load test in which an abnormal load expected to be caused by an external impact or other factors in a normal operating state is applied to a test sample, and the maximum load that the test sample can resist is measured. In the seizure test RL standard table of Table 3 below, stages 1 to 3 correspond to a normal operating state, and stage 4 is a test in which a load is increased gradually from 45 kgf while a normal operating state (1000 rpm, feeding of lubricating oil) is maintained. When the test sample resists a load of 1,300 kgf or more, it is determined to satisfy the standard.

TABLE-US-00002 TABLE 2 Test conditions in each step Feeding of Cumulative Stage rpm Load (kgf) Time (sec) lubricating oil time (sec) 1 100 45 30 30 2 1,300 45 60 60 3 1,300 200 90 150 4 1,300 200 480 630 5 2,300 200 150 780 6 2,300 200 1,200 X

TABLE-US-00003 TABLE 3 Test conditions in each step Feeding of lubricating Stage rpm Loading (kgf) Time (sec) oil 1 100 45 30 2 1,000 45 60 3 1,000 45 480 4 1,000 1850 1,200

[0031] As can be seen in Table 1, the conditions of the Preparation Examples 1 to 4 passed both the ML and RL test standards. In other words, it can be seen that the liquid lubricating coating composition having a solid content of 20-26 wt % and a viscosity of 30-40 cP satisfied all the test standards. However, it can be seen that, when the solid content and the viscosity were out of the above ranges, the composition did not satisfy the test standards. Thus, it can be seen that, when the contents of a binder, a solid lubricant, other additives and a solvent in a lubricating coating composition for coating the surface of an iron or aluminum-based swash plate are controlled within a very narrow range, the composition can provide a product that satisfies the standards.

[0032] As described above, according to the present invention, changes in the solid content and viscosity of a lubricating coating composition for coating the surface of an iron or aluminum-based swash plate have a great effect on the adhesion of the composition to the surface in drying and calcining processes, and the lubricating ability of the composition.

[0033] Although the preferred embodiments of the present invention have been disclosed for illustrative purposes only, those skilled in the art will appreciate that various modifications and alterations are possible, without departing from the essential features of the present invention. Therefore, the disclosed embodiments are considered to be illustrative in all respects and not restrictive, and the scope of the technical idea of the present invention is not limited to these embodiments. The scope of protection of the present invention should be defined by the appended claims, and all equivalents that fall within the technical idea of the present invention are intended to be embraced by the scope of the claims of the present invention.