CN113853421B

CN113853421B - Antifriction coating formulation composition

Info

Publication number: CN113853421B
Application number: CN202080034163.5A
Authority: CN
Inventors: M·穆什拉什; R·摩根; M·夏尔马; G·韦伯
Original assignee: DDP Specialty Electronic Materials US 9 LLC
Current assignee: DDP Specialty Electronic Materials US 9 LLC
Priority date: 2019-05-08
Filing date: 2020-05-07
Publication date: 2023-03-14
Anticipated expiration: 2040-05-07
Also published as: WO2020227496A1; US20220177800A1; KR20220006530A; CN113853421A; EP3966300A1; JP2022532146A

Abstract

An antifriction coating formulation composition is disclosed. The antifriction coating formulation composition comprises (a) a resin and (b) a metal sulfide comprising molybdenum and cobalt, and optionally (c) a solid lubricant other than the metal sulfide and (d) a solvent. The coating film formed from the antifriction coating formulation composition provides better abrasion resistance and a good coefficient of friction.

Description

Antifriction coating formulation composition

Technical Field

The present invention relates to an antifriction coating formulation composition, an antifriction coating formed from the composition, and a sliding member having the antifriction coating.

Background

Antifriction coatings for improving the sliding properties of components for industrial machinery, construction machinery and automobiles are known in the art. Typical antifriction coating compositions comprise a resin binder, a solid lubricant, and a solvent. The role of the solid lubricant is to reduce friction and wear of the contacting surfaces in relative motion and to provide protection from damage. Well-known solid lubricants include molybdenum disulfide (MoS) ₂ ) Graphite and Polytetrafluoroethylene (PTFE).

Although antifriction coatings comprising molybdenum disulphide show excellent sliding properties, there is always a desire to continue to improve wear properties. WO 2016/073341A discloses connecting rods comprising a wear resistant coating. The wear resistant coating comprises a polymer matrix, a solid lubricant and hard particles, wherein the solid lubricant is selected from the group consisting of molybdenum disulfide, graphite, tungsten sulfide, hexagonal boron nitride, polytetrafluoroethylene and metal sulfides. It may contain one or more solid lubricants. US 7,368,182B discloses multiple coatings to improve wear resistance.

Mixed metal sulphides are known in the catalytic art, e.g. WO 2011/008513A and US 4,752,623B. These prior art references disclose cobalt-molybdenum disulfides in which a small amount of cobalt metal is incorporated into the parent MoS ₂ In the structure. In the use of the catalyst, moS is incorporated ₂ The second metal (i.e., cobalt) in the structure acts as a catalyst promoter. However, these prior art references do not mention the use of mixed metal sulfides as solid lubricants in antifriction coatings.

Disclosure of Invention

Disclosed herein is an antifriction coating formulation composition comprising: a resin and (b) a metal sulfide comprising molybdenum and cobalt, and optionally (c) a solid lubricant other than the metal sulfide and (d) a solvent. Such antifriction coating formulation compositions can provide antifriction coatings that exhibit relatively high wear resistance.

Also disclosed herein is a coated film formed from the antifriction coating formulation composition.

Further disclosed herein is a sliding member having a lubricating film formed from the antifriction coating formulation composition.

Drawings

Fig. 1 shows the geometry of the test apparatus for the ball plate wear test.

FIG. 2 shows the geometry of the LFW-1 (ring block) test.

Detailed Description

The antifriction coating (AFC) formulated compositions disclosed herein comprise at least two ingredients: (a) A resin and (b) a metal sulfide comprising molybdenum and cobalt, wherein the molar ratio of molybdenum to cobalt in the metal sulfide is from 99 to 1 to 99.

Resin (a)

The resin (a) used in the friction reducing coating formulation composition is used as a matrix polymer for a coating film described later. Examples of resins include polyamideimide, polyimide, polyamide, epoxy, phenolic, polybenzimidazole, polyphenylsulfonate, polyetheretherketone, polyurethane, poly-butyl titanate, polyacrylic-alkyd, polyetherketoneketone (PEKK), polyoxymethylene (POM), polybutylene terephthalate (PBT), fluoropolymer, and mixtures thereof. Preferred resins include polyamideimides, (polyimides) and (polyamides), with polyamideimides being most preferred.

Preferably, the resin is present in the antifriction coating formulation composition in the range of 10 to 90 parts by weight relative to 100 parts by weight of the solids content of the antifriction coating formulation composition. More preferably, the resin content is 20 to 80 parts by weight, and even more preferably 30 to 70 parts by weight, relative to 100 parts by weight of the solids content of the antifriction coating formulation composition. In this specification, the weight of the solids content of the antifriction coating formulation composition refers to the total weight of the solids content of the AFC formulation composition (i.e., resin, metal sulfide, solid lubricant, and additional ingredients in solid form).

Metal sulfide (b)

The metal sulfide used in the friction reducing coating formulation composition comprises molybdenum and cobalt. Since the metal sulfide contains at least two metals, it is also referred to as a mixed metal sulfide. When the metal element of the metal sulfide is cobalt and molybdenum, the metal sulfide may also be referred to as cobalt-molybdenum disulfide, and may be represented by the formula (Co, mo) S ₂ Or Co _x Mo _(1-x) S ₂ A description is given. In the formula, x is a number less than 1.

The molar ratio of molybdenum to cobalt in the metal sulfide is in the range of 99 to 1 to 99. The molar ratio may be selected based on the desired characteristics of the friction reducing coating formulation composition comprising the metal sulfide. When the antifriction coating formulation composition comprising a metal sulfide is used in an antifriction coating having higher wear resistance, the preferred molar ratio of molybdenum to cobalt is in the range of Mo: co 85 to Mo: co 98. Within this molar ratio range, it is believed that a small amount of cobalt metal replaces the parent MoS ₂ The wear resistance of the structured molybdenum metal, and hence the film comprising the metal sulphide, is improved whilst the basic anti-friction properties are maintained. More preferably, the ratio of molybdenum to cobalt in the metal sulfide is Mo: co 85 to 5, still more preferably, the ratio is Mo: co 90.

The metal sulfides can be obtained by the methods described in the following publications: 1) Cobalt-molybdenum sulfide catalyst prepared by in situ activating a bimetallic (Cobalt-molybdenum) alkylthiomolybdate, nava et al, catalysis Letters 2003, vol.86, no. 4, p.257; and 2) The roll of Structural Carbon in Transition Metal catalysts hydro-treating catalysts, belhault, et al, journal of Catalysis [ Role of Structural Carbon in Transition Metal sulfide Hydrotreating catalyst, berhault et al, proceedings of Catalysis ]2001, vol.198 (1), pp.9-19.

The metal sulfides synthesized by this method produce very dark solids with a lamellar structure, and MoS ₂ Similar in appearance. The primary particle size of the metal sulfide tends to agglomerate in clusters of preferably 0.1 to 10 microns, more preferably 1 to 6 microns. The size can be measured by a particle analyzer such as laser diffraction scattering, or it can be estimated from Scanning Electron Microscope (SEM) images.

The amount of the metal sulfide in the resin composition ranges from 10 to 60 parts by weight, preferably from 20 to 40 parts by weight, relative to 100 parts by weight of the solid content of the antifriction coating formulation.

Solid lubricant (c)

The antifriction coating formulation composition may optionally comprise a solid lubricant (c). The solid lubricant is different from the metal sulfide (b) disclosed above. Non-limiting examples of solid lubricants include graphite, polytetrafluoroethylene (PTFE), polyethylene (PE), and mixtures thereof. Graphite is preferred.

The solid lubricants in the antifriction coating formulation compositions described herein are typically lamellar structures in which the "plates" slide relatively easily over one another. These materials naturally aggregate into larger agglomerates, which are easily broken down into smaller particles during the preparation and mixing of the antifriction coating. The average primary particle diameter of the solid lubricant is preferably 0.1 to 10 micrometers, more preferably 1 to 6 micrometers.

When the antifriction coating formulation composition contains the solid lubricant, the amount of the solid lubricant ranges from 1 to 100 parts by weight, preferably from 5 to 50 parts by weight, and more preferably from 10 to 30 parts by weight, relative to 100 parts by weight of the solid content of the antifriction coating formulation composition.

Solvent (d)

The antifriction coating formulation composition may optionally comprise a solvent (d) for the purpose of improving the coating properties. The solvent may be selected according to the type of the binder resin. Useful solvents include, for example, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; esters, such as methyl acetate and ethyl acetate; aromatic hydrocarbons such as toluene and xylene; alcohols, such as ethanol, 2-propanol, diacetone alcohol (DAA); organic halogen compounds such as methyl chloroform, trichloroethylene and trichlorotrifluoroethane; n-methyl-2-pyrrolidone (NMP), N-ethyl-2-pyrrolidone (NEP), 1, 3-dimethyl-2-imidazolidinone (DMI), 3-methoxy-N, N-dimethylpropionamide, methylisopyrrolidone (MIP), dimethylformaldehyde (DMF), dimethylacetal (DMAC), and mixtures thereof. Preferred solvents are DMI, NEP and xylene.

Additional Components (e)

The antifriction coating formulation compositions described herein may optionally contain additional ingredients such as UV absorbers, stabilizers, antioxidants, leveling agents, deforming agents, thickeners, pigments, dyes and dispersants, as long as the objects of the present invention are not impaired. When present, the amount of additional ingredients will preferably range from 0.1 to 5 parts by weight relative to 100 parts by weight of the solids content of the antifriction coating formulation composition.

Although the metal sulfide (b) of the composition comprises cobalt and molybdenum (Co) _x Mo _(1-x) S ₂ ) However, other metal sulfides (M) may be used _x Mo _(1-x) S ₂ And M is tungsten, tantalum or nickel).

The antifriction coating formulation compositions described herein may be prepared using methods known to those skilled in the art, for example, by mixing the described ingredients in any suitable order using conventional equipment. For example, the resin is dissolved and the metal sulfide and other ingredients (if present) are introduced.

Coating film

The second aspect of the present invention relates to a coating film formed from the above antifriction coating formulation composition. A film is formed by applying the above composition on the surface of a substrate and then heating it to cure the applied composition. The substrate may be metal, plastic, wood, elastomer, composite, and the like. The coating may be applied to the surface by any conventional method such as brushing, dipping and spraying. The coating thickness is determined by the desired characteristics and the lifetime of the film, but is typically 5 to 20 microns. Once the antifriction coating formulation composition is applied to the surface of the substrate, it is dried to evaporate the solvent (if applicable) and cured to form a coated film. The curing method depends on the nature of the substrate and the type of resin. For example, curing may be performed in an oven at a temperature of 100 to 280 degrees celsius for 30 to 90 minutes.

Sliding member

A third aspect of the invention relates to a sliding member having a lubricating film formed from the antifriction coating formulated composition described above. The sliding member may be selected from a swash plate of a compressor, an engine tappet, a camshaft, a crankshaft, engine metal, an engine piston, an engine fastener, a sliding bearing, a piston ring, a gear, a door lock, a brake pad, or a brake clip.

Examples of the invention

Example series I: abrasion resistance test

The compositions of the examples were prepared using the raw materials shown in table 1.

TABLE 1

Co _x Mo _(1-x) S ₂ Preparation of

Stoichiometric amount of ammonium sulfide [ (NH) ₄ ) ₂ S]And ammonium heptamolybdate [ (NH) ₄ ) ₂ Mo ₇ O ₂₄ -4H ₂ O]Combine in aqueous solution and stir at 60 ℃ for 1 hour (during which time the solid will completely dissolve). The resulting aqueous solution was mixed with a stoichiometric amount of cobalt acetate [ Co (C) at 60 deg.C ₂ H ₃ O ₂ ) ₂ ]Was added dropwise to the acetic acid solution from an addition funnel and allowed to stir for one hour. The obtained solid material { (NH) ₄ ) ₄ [Co(MoS ₄ ) ₃ ]Filter and dry at 80 ℃. The dried material was then placed in a nitrogen purged furnace, ramped up to 500 ℃, and held for about one hour to reduce the solids to the final sulfide product. After heating, the furnace was allowed to cool autothermally while being kept under a nitrogen atmosphere.

Co _x Mo _(1-x) S ₂ Is characterized by

As synthesized, co by powder X-ray diffraction _x Mo _(1-x) S ₂ Shows the presence of the precursor MoS ₂ Those same phases in the structure; however, the peaks are weaker and broader due to the nanocrystalline structure. By scanning electron microscope/electron dispersion spectroscopy (SEM-EDS), cobalt is relatively uniformly distributed in the grains, and the particle size is estimated to be about 2 microns or less. These appear to be clusters of smaller primary particle sizes on the order of hundreds of nm, and there are also some large agglomerates. Large agglomerates in the friction reducing coating formulation are likely to break up during the milling process.

The mixed metal sulfides were analyzed by X-ray fluorescence to obtain the true stoichiometric ratio of Co to Mo. For simplicity, the data in the examples are shown in rounded ratios.

Test method

Test 1: ball and plate wear test

The ball panel abrasion test was performed according to ASTM G-133. A1/2' diameter steel ball (11) is brought into contact with a friction reducing coating (21) which has been applied to a steel (or other material) sample using a force of 10N. This load was maintained throughout the test for a total of 10,000 times (or 5000 cycles) as the test specimen was reciprocated back and forth with a stroke length of 4 mm. The geometry of the test device (1) from ASTM G-133 is shown in FIG. 1 for reference.

Test 2: LFW-1 test

The LFW-1 test is another wear test typically performed on antifriction coatings in accordance with ASTM-D2714. This dry test was performed on a coated test ring (Rockwell hardness 60) at 72rpm under a relatively high load (2860N); the geometry is such that the upper mass applies a load to the ring rotating on the shaft below. See figure 2 for a schematic diagram of the wear test geometry.

Examples of the invention

The antifriction coatings disclosed in tables 2 and 3 were prepared and tested. Mixing the components (resin, moS) ₂ Or Co _x Mo _(1-x) S ₂ Solid lubricant, solvent and additives) were mixed by milling and subsequent filtration and then sprayed onto the substrate to produce test films. The test film was heated at 80 degrees celsius for 10 minutes, followed by 230 degrees celsius for 1 hour to cure the resin.

TABLE 2

Sample (I)	1	2	3	4	5	6	7
								A-1	100.00	100.00	100.00	100.00	100.00	100.00	100.00
A-2	0	0	0	0	0	0	0
								C-1	8.01	8.01	8.01	8.01	8.01	8.01	12.67
C-2	0	0	0	0	0	0	0
								B-1	0	0	51.28	0	0	0	0
B-2	0	0	0	51.28	0	0	0
								B-3	51.28	0	0	0	0	0	0
B-4	0	51.28	0	0	0	0	0
								B-5	0	0	0	0	51.28	0	0
B-6	0	0	0	0	0	51.28	0
								B-7	0	0	0	0	0	0	81.60
D-1	0	0	0	0	0	0	0
								D-2	316.67	316.67	316.67	316.67	316.67	316.67	733.18
D-3	0	0	0	0	0	0	0
								E-1	0.62	0.62	0.62	0.62	0.62	0.62	0.93
In total	476.58	476.58	476.58	476.58	476.58	476.58	928.38
								Average CoF	0.16	0.138	0.214	0.153	0.208	0.184	0.16
Depth of grinding mark (%)	28	18	36	100	77	37	52

TABLE 3

Example series II: wear life test

Long term ball panel testing was performed using the formulations of samples 8 and 11. The film thickness of samples 8 and 11 was 13.7 and 11.0 microns, respectively. The formulation of sample 8 lasted longer than sample 11 before failure. The control sample of sample 11 was tested in winter and summer to ensure that large changes in relative humidity did not have a significant effect.

TABLE 4

Mo ratio is also shown in Table 4. Using X-ray photoelectron spectroscopy, the ratio of sulfur to molybdenum was calculated from the peaks corresponding to the relevant valence states and corrected for relative sensitivity. These estimates are reasonable as indicated by the values on the film surface of 1.94 (sample 11) and 1.93 (sample 8). Including standard MoS ₂ Sample 11 of (a) indicates that sulfur is present as sulfate rather than sulfide for all samples with high wear times or failures. This is a key difference from sample 8 with mixed metal sulfides, although the sulfide to Mo ratio is still very similar to the original film surface value. Although not fully understood, this difference does support the view that MoS is ₂ The presence of cobalt in the structure may be delayed or inhibitedOxidation associated with wear.

Claims

1. An antifriction coating formulation composition comprising:

(a) Resin and

(b) A metal sulfide comprising molybdenum and cobalt,

wherein the molar ratio of molybdenum to cobalt in the metal sulfide is 99 to 1 to 99; and is

Wherein the metal sulfide is of the formula Co _x Mo _(1-x) S ₂ Cobalt-molybdenum disulfide described; where x is a number less than 1.

2. An antifriction coating formulation composition in accordance with claim 1 wherein the amount of metal sulfide is 10 to 60 parts by weight relative to 100 parts by weight of the solids content of the antifriction coating formulation composition.

3. The antifriction coating formulation composition of claim 1 wherein the average particle size of the metal sulfide is 0.1 to 10 microns as observed by scanning electron microscopy.

4. The antifriction coating formulation composition of claim 1 further comprising at least one of (c) a solid lubricant other than the metal sulfide, wherein the solid lubricant is selected from the group consisting of graphite, polytetrafluoroethylene, and polyethylene, and (d) a solvent.

5. The antifriction coating formulation composition of claim 1 wherein the resin is selected from the group consisting of polyamideimide, polyimide, polyamide, epoxy, phenolic, polybenzimidazole, polyphenylsulfonate, polyetheretherketone, polyurethane, poly-butyl titanate, polyacrylic-alkyd, polyetherketoneketone, polyoxymethylene, polybutylene terephthalate, and fluoropolymer.

6. An antifriction coating formulation composition in accordance with claim 1 wherein the ratio of molybdenum to cobalt in the metal sulfide is from 85 to 15 to 95 to 5.

7. A coated film formed from the antifriction coating formulation composition of claim 1.

8. A coated film according to claim 7, wherein the film is formed on a metal surface of a part.

9. A sliding member having a lubricating film formed from the antifriction coating formulation composition of claim 1.

10. A sliding member as claimed in claim 9 wherein the sliding member is selected from the group consisting of a compressor swash plate, an engine tappet, a camshaft, a crankshaft, engine metal, an engine piston, an engine fastener, a sliding bearing, a piston ring, a gear, a door lock, a brake pad and a brake clip.