JPH10120980A - Abrasion-resistant and nontacky coating agent and sliding member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a coating agent capable of making its abrasion resistance compatible with its nontackiness by a simple coating process, and useful in highly durable sliding members, by compounding a fluororesin, heat-resistant resin and iron oxide powder, etc. SOLUTION: First, 100 pts.wt. of a fluororesin (e.g. polytetrafluoroethylene resin) is compounded with 100-150 pts.wt. of a heat-resistant resin (e.g. polyamide-imide resin) and 5-20 pts.wt. of iron oxide powder (e.g. ferrous oxide) to form a homogeneous composition, which, in turn, is diluted with a mixed solvent composed of N-methyl-2-pyrrolidone(NMP), dimethylformamide(DMF), xylene and ethyl acetate so as to be about 23wt.% in solid content, thus obtaining the objective coating agent to be used in sliding members because of having advantages as mentioned above.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a coating agent and a sliding member, and more particularly to a coating agent excellent in abrasion resistance and non-adhesion and a sliding member using the same.

[0002]

2. Description of the Related Art For a sliding member in which it is difficult to produce a product or a part itself with a non-adhesive member, a non-adhesive coating agent is usually applied to the surface to form a non-adhesive coating layer. It has been practiced to form non-tacky products or parts. Conventionally, as such a non-adhesive coating agent, those in which a solid lubricant is blended with a binder resin or the like are known, and the solid lubricant includes molybdenum disulfide, a fluorine-based resin, graphite, and the like. Polyimide resin, polyamide imide resin, phenol resin, epoxy resin and the like are frequently used as the binder resin. Also,
When it is necessary to provide abrasion resistance together with non-stickiness,
There is also known a coating agent obtained by adding various needle-like or scaly fillers such as calicum whisker and wollastonite to a coating layer.

[0003]

However, the coating agent comprising a solid lubricant and a binder resin has insufficient abrasion resistance, and the coating layer formed by the coating agent is worn over a short period of time. However, there is a problem that the base of the base material is easily exposed. In addition, in the case of a coating agent to which various fillers in the form of needles or flakes are added, a simple application method is difficult, the surface roughness of the coating layer is extremely rough, and its own wear resistance is improved. However, there is a problem that a mating material is worn or non-adhesiveness is reduced. As described above, a coating agent which is practical and has both abrasion resistance and non-adhesiveness has not been obtained. Further, there is a problem that the sliding member formed by forming a non-adhesive coating layer by applying a coating agent has poor durability. The present invention has been made in order to cope with such a problem, and uses an abrasion-resistant / non-adhesive coating agent capable of achieving both abrasion resistance and non-adhesion by a simple application method, and using the same. An object of the present invention is to provide a sliding member having a wear-resistant and non-adhesive coating layer formed thereon.

[0004]

SUMMARY OF THE INVENTION According to the present invention, the wear resistance
The non-adhesive coating agent is characterized by containing at least a fluorine-based resin, a heat-resistant resin, and iron oxide powder.

Further, the heat-resistant resin is a polyimide resin, and furthermore, is a polyamide-imide resin. The fluorine-based resin is a polytetrafluoroethylene resin.

[0006] The compounding ratio of the wear-resistant and non-adhesive coating agent is 100 parts by weight of the fluororesin and 100 to 1 of the heat-resistant resin.
It is characterized by containing at least 50 parts by weight and 5 to 20 parts by weight of iron oxide powder.

A sliding member according to the present invention is a sliding member having a slidable coating layer on the surface of a substrate, wherein the slidable coating layer is the above-mentioned abrasion-resistant non-adhesive coating agent. Characterized in that it is a resin coating layer formed by using

According to the present invention, by combining iron oxide powder with a fluorine-based resin and a heat-resistant resin, it is possible to achieve both abrasion resistance and non-adhesion by a simple coating method such as spray coating, and to improve durability. It has been made based on the finding that a sliding member excellent in the above can be obtained.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Iron oxide powder used in the present invention,
The fluorine resin and the heat resistant resin will be described. The iron oxide powder that can be used in the present invention is iron oxide (I
I), diiron trioxide, triiron tetroxide and the like, all of which can be used. As the shape of these iron oxides, powders of all shapes such as a sphere, a scale, and a needle can be used. The average particle size of the iron oxide powder may be any particle size, for example, 0.1 μm to 10 μm, specifically 0.1 μm to 1 μm
And more preferably 0.2 μm to 0.5 μm. When the average particle size is less than 0.1 μm, the particles are agglomerated and the dispersibility deteriorates. When the average particle size exceeds 1 μm, the wear resistance of the coating layer becomes unstable. The average particle size of the iron oxide powder can be measured by the BET method, but is not particularly limited to this measurement method.

As the fluororesin which can be used in the present invention, any resin can be used as long as it has low friction, can impart non-adhesiveness to the coating layer, and has heat resistance enough to withstand the operating temperature atmosphere of the sliding member. Can be. Specifically, polytetrafluoroethylene (melting point 327 ° C, continuous use temperature 260 ° C, hereinafter abbreviated as PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (melting point 270 ° C, continuous use temperature 200 ° C), Tetrafluoroethylene-perfluoroalkylvinyl ether copolymer (melting point 310 ° C, continuous operating temperature 260 ° C), ethylene-tetrafluoroethylene copolymer (melting point 270 ° C, continuous operating temperature 150 ° C), polychlorotrifluoroethylene (melting point 210 ° C, continuous operating temperature
120 ° C.) and ethylene-chlorotrifluoroethylene copolymer (melting point 240 ° C., continuous use temperature 150 ° C.). These may be each alone or two or more copolymers or terpolymers.

Among them, PTFE is composed of a repeating unit of -CF ₂ CF _2- , and has a high melt viscosity of about 10 ¹⁰ to 10 ¹¹ Pa · s at about 340 to 380 ° C., and is hard to flow even if it exceeds the melting point. It has the highest heat resistance among fluoroplastics, has excellent properties even at low temperatures, and has excellent slidability and non-adhesiveness (contact angle of 104 ° (water)). It is suitable for the invention. For this reason, the parts to be used in the present invention are not only used in an atmosphere of -273 ° C. to 260 ° C., but also at room temperature (for example,
(0 ° C to 25 ° C) or more, especially for parts used continuously in an atmosphere of 60 ° C to 260 ° C. PTFE
Among them, when used, it is particularly preferable to use lubricant-grade powdered PTFE. Commercially available lubricant-grade powdered PTFE includes Fluon L169, 170 and 171 (all trade names of ICI, UK), and Polyflon M
15, Lubron L-2, L-5, LD-1 (or more,
Daikin Industries, Ltd.), Teflon 7J, TLP-
10, TLP-10F-1 (trade name, manufactured by DuPont), Fluon G163 (trade name, manufactured by Asahi Glass Co., Ltd.) and the like. Here, the lubricant-grade powder PTFE refers to recycled PTFE obtained by pulverizing PTFE that has been calcined once, or PTFE powder obtained by subjecting PTFE to gamma irradiation treatment to reduce the molecular weight. As a commercially available PTFE for a lubricant which has been subjected to γ-ray irradiation, KT400H (trade name, manufactured by Kitamura Co., Ltd.) can be exemplified.

The form of PTFE may be a molding powder or a fine powder of a so-called solid lubricant. Its average particle size is 0.1-20 μm, preferably 0.2-10
It is in the range of μm. When the average particle size is within this range, no agglomeration or the like occurs in the coating agent, and the smoothness of the coating layer after application, drying and baking is maintained.

The heat-resistant resin that can be used in the present invention has heat resistance that does not deteriorate due to heat during use of the sliding member, binds a fluororesin powder, and firmly adheres the coating layer to the base. Any resin that can be used can be used. Specifically, a polyimide resin, an epoxy resin, a phenol resin, a silicone resin, and the like can be given. Among these, polyimide resins are preferable because of their excellent heat resistance and adhesion to the base.

The polyimide resin that can be used in the present invention is a resin having at least an imide bond in a molecule, and does not thermally degrade when a sliding member is used.
Any resin can be used as long as it binds the fluororesin and the iron oxide powder and has excellent adhesion to the base. For example, polyimide resin, polyamide imide resin,
Examples thereof include polyester imide resins and polyester amide imide resins. Among these polyimide resins, a polyimide resin and a polyamideimide resin are preferable. Further, an aromatic polyimide resin or an aromatic polyamideimide resin in which an imide bond or an amide bond is bonded via an aromatic group is particularly preferable. When the resin is an aromatic resin, the binding property between the fluorine resin and the iron oxide powder is excellent, and the obtained coating layer has excellent heat resistance.

The polyimide resin is a polyimide precursor obtained by a ring-opening polyaddition reaction between an acid dianhydride and a diamine in an aprotic polar solvent such as N-methyl-2-pyrrolidone (NMP) or dimethylacetamide (DMAC). It can be obtained by, for example, heating and dehydrating and ring-closing the polyamide carboxylic acid. As the resin component in the abrasion-resistant / non-adhesive coating agent, use it even in the state of polyamide carboxylic acid, in the state of polyimide, or even in the state where these are mixed. Can be.

The polyamide imide resin is a resin having an imide bond and an amide bond in the molecule. The imide bond of the aromatic polyamide-imide resin may be a precursor such as polyamic acid, a closed imide ring, or a mixture of these. Such an aromatic polyamide-imide resin,
Aromatic primary diamines such as polyamide imides prepared from diphenylmethane diamine and aromatic tribasic anhydrides such as mono- or diacyl halide derivatives of trimellitic anhydride, aromatic tribasic anhydrides and aromatic diisocyanate compounds For example, there are polyamide imides produced from diphenylmethane diisocyanate, and polyamide imides having a higher ratio of imide bonds than amide bonds, such as aromatic, aliphatic or alicyclic diisocyanate compounds and aromatic tetrabasic acid. There are polyamide imides produced from dianhydrides and aromatic tribasic acid anhydrides, and any polyamide imide resin can be used.

The mixing ratio of each component in the resin coating layer formed by the abrasion-resistant and non-adhesive coating agent according to the present invention is 100 to 150 parts by weight of the polyimide resin and 100 to 150 parts by weight of the polyimide resin. 5-20 parts by weight of iron oxide powder. By blending each component in this range, the functions can be exhibited by using a polyimide resin as a binder and a fluorine resin as an abrasion resistance improver. If the amount of the polyimide resin is less than 100 parts by weight with respect to 100 parts by weight of the fluorine-based resin, the adhesion of the coating layer is impaired and causes peeling. On the other hand, if it exceeds 150 parts by weight, the sliding characteristics and the non-adhesiveness are unfavorably deteriorated. If the iron oxide powder is less than 5 parts by weight based on 100 parts by weight of the fluororesin, the abrasion resistance is not improved, and if it exceeds 20 parts by weight, the adhesion between the base and the coating layer is reduced.

In the case of dipping or spray coating, the coating agent according to the present invention is obtained by dispersing or dissolving a fluorine resin, a polyimide resin and iron oxide powder in a solvent. Solvents include ketones such as acetone and methyl ethyl ketone, esters such as methyl acetate and ethyl acetate, aromatic hydrocarbons such as toluene and xylene, and organic halogenated compounds such as methyl chloroform, trichloroethylene and trichlorotrifluoroethane. , N-methyl-2-pyrrolidone (NMP),
Non-protonic polar solvents such as methylisopyrrolidone (MIP), dimethylformamide (DMF), and dimethylacetamide (DMAC) can be used.
These solvents can be used alone or as a mixture.

When the coating agent used for dipping or spray coating is used, the solid content of the fluororesin, the polyimide resin and the iron oxide powder is 5 to 100 parts by weight (solids concentration: 4.76 ~
50% by weight), preferably with a solid content of 2%.
It is 5 to 50 parts by weight (solids concentration: 20 to 50% by weight). If the solid content is less than 5 parts by weight, sufficient resin will not adhere to the surface of the underlayer. Further, the number of processing steps for the excess solvent increases, which is disadvantageous in the processing. 1 solids
If it exceeds 00 parts by weight, the solid content will be too large,
It becomes easy to cause liquid clogging of nozzles of atomizing means such as a spray gun. In addition, a leveling agent, a dispersant, and the like that are usually used for a coating agent can be added.

Various methods such as a dipping method (dip coating method), a spray coating method (atomizing coating method), and a brush coating method can be adopted as a method of applying the above-mentioned coating agent on the base surface. In the coating method by the spray coating method (atomization coating method), the coating liquid is attached to the object to be coated in the form of fine particles, so that the thickness of the coating film can be accurately formed. The coating layer can be formed by powder coating or the like. In that case, solventless coating is performed.

The coating layer applied by these methods is:
A layer thickness of 5 to 40 μm after firing is preferred. Layer thickness
If the thickness is less than 5 μm, local abrasion may occur when the coating layer has one-sided contact, etc. If the thickness exceeds 40 μm, peeling of the coating layer tends to occur, which is not preferable. The preferable thickness range of the coating layer is 10 to 30.
μm.

The sliding member coated with the coating agent is fired after drying. Drying should be carried out at a temperature between 50 ° C and 100 ° C for 30 minutes.
It is preferable that the holding time be between 1 minute and 120 minutes. Thereby, foaming of the coating film and the like can be suppressed.

The sintering temperature of the coating layer depends on the type of heat-resistant resin.
0 ° C is appropriate. If the temperature is lower than 180 ° C., the curing reaction of the polyamide-imide resin does not proceed, and it is presumed that the adhesion of the coating layer to the base surface cannot be expected. If the temperature exceeds 280 ° C., especially the melting point of the fluororesin, the decomposition of the fluororesin starts to progress, which is not preferable. In addition, since the adhesion of the coating layer to the base surface becomes equilibrium at around 280 ° C., it is preferable to bake at 280 ° C. or less in consideration of the power consumption required for temperature rise.

The firing of the polyamide-imide resin is performed, for example,
80 ℃ ~ 130 ℃ ~ 180 ℃ divided into several stages, 3
It is preferable to gradually raise the temperature every 30 minutes to 120 minutes within the range of 0 minutes to 240 minutes. Thereby, the curing reaction of the binder resin and the like progresses gradually and reliably, and a coating layer having uniform adhesion strength can be formed. In addition, it is also possible to prevent the formation of wrinkles, wrinkles, cracks and the like in the coating layer.

The retention time of the maximum temperature during firing depends on the maximum temperature during firing, but it is about 12 hours when the maximum temperature is 180 ° C., and about 60 minutes when the maximum temperature is 240 ° C. At 280 ° C, about 30 minutes is preferable. When the holding time at each maximum temperature is extremely shorter than the predetermined time, the curing of the polyamideimide resin is insufficient, and it becomes difficult to obtain desired adhesion and hardness. On the other hand, if the holding time is extremely longer than the predetermined time, it is not preferable because the power consumption required for raising the temperature and the manufacturing time are long.

In the case of a polyimide resin, the firing temperature of the coating layer is suitably from 200 to 350 ° C. If the temperature is lower than 200 ° C., the imidization reaction of the precursor polyamic acid may not be sufficient. If the temperature exceeds 350 ° C., especially if the melting point of the fluororesin is exceeded, the decomposition of the fluororesin starts undesirably.

The firing temperature is also affected by the base material. For example, when the base material is a lightweight cast metal-based alloy such as an aluminum alloy, etc., if the firing temperature exceeds 250 ° C., the thermal effect on the base material ( For example, baking is preferably performed at 250 ° C. or less because warpage may occur.

The cooling after the sintering step may be carried out through the reverse of the step of the sintering step, or may be carried out slowly over a period of about 60 to 180 minutes. By slow cooling in this way, the coating layer and the base material shrink uniformly and accurately with each other, and a highly accurate sliding member can be obtained. The total firing time is preferably adjusted to about 2 to 10 hours.

The sliding member according to the present invention is excellent in abrasion resistance and non-adhesiveness and is durable. Therefore, the sliding member such as a washer, a vane, a slide guide, a guide pin, a curtain wall member, and a sliding portion of a seismic isolation device is used. It can be suitably used for sliding parts.

[0030]

EXAMPLES Materials used in Examples and Comparative Examples of a wear-resistant and non-adhesive coating agent are shown below. (1) Iron oxide powder: Todacolor 160ED (average particle size)
(0.27 μm) (trade name, manufactured by Toda Kogyo Co., Ltd.) (2) Fluorinated resin: Fluon L169 (ICC
(3) Polyamideimide resin: Torlon AI-10 (trade name, manufactured by Teijin Amoco Engineering Plastics) (4) Molybdenum disulfide: Molycoat Z (trade name, manufactured by Dow Corning) (5) ) Bronze powder: At-35 (trade name, manufactured by Fukuda Metal Foil & Powder Co., Ltd.) (6) Graphite powder: Lonza KS10 (trade name, manufactured by Lonza)

Examples 1 to 3 and Comparative Examples 1 to 7 Abrasion-resistant and non-adhesive coating agents were prepared as follows. Polyamideimide resin (Toron AI-10)
The resin solution is dissolved in N-methyl-2-pyrrolidone (NMP), and a fluorine-based resin (Fluon L169) and iron oxide powder (Todacolor 160ED) are blended into this resin solution to form a uniform composition. % So that N-methyl
-2-pyrrolidone (NMP), dimethylformamide (D
A coating agent was obtained by diluting with a mixed solvent of MF), xylene and ethyl acetate. Table 1 shows the composition of the coating agent.
Shown in For Comparative Examples 5 to 7, coating agents using molybdenum disulfide, bronze powder, or graphite powder instead of iron oxide powder were prepared.

Using these coating agents, disk-shaped sliding members having a resin coating layer were prepared. First, a coating agent was sprayed on the surface of a disk-shaped aluminum alloy (AC8C) sliding member by spray coating so that the thickness of the resin coating layer after firing became about 20 μm. The sliding member is dried at 80 ° C for 15 minutes,
The temperature was raised to 160 ° C. over 30 minutes and kept at 160 ° C. for 30 minutes. Then, the temperature was raised to 160 to 240 ° C over 30 minutes,
Hold for 60 minutes. Thereafter, the disc was naturally cooled to room temperature over 60 minutes to obtain a disk-shaped sliding member having a resin coating layer.

The obtained disk-shaped sliding member was subjected to a wear resistance test using a ball-on-disk tester under the conditions shown in Table 2. Table 1 shows the results.

[0034]

[Table 1]

[0035]

[Table 2]

As shown in Table 1, iron oxide 5 to 20 parts by weight, polyimide resin 1
The examples containing 00 to 150 parts by weight had a very small amount of wear of the resin coating layer, a small coefficient of friction, and were excellent in both abrasion resistance and non-adhesion as compared with the comparative examples.

Next, the characteristics of the coating layer were evaluated by the following methods using the above-mentioned samples. Table 3 shows the results. (1) Adhesion Strength The adhesion strength was evaluated by a cross-cut test using a disk-shaped sliding member having a resin coating layer formed thereon as a test piece. The cross-cut test is to cut 100 perpendicular grids by cutting 11 perpendicular and horizontal lines at 1 mm intervals that reach the base almost at the center of the test piece with a cutter knife, and after attaching cellophane tape from above, This is a method in which the adhesive strength is evaluated based on the number of grids in which the cellophane tape is peeled off and the coating material remains on the substrate. (2) Surface Hardness The surface hardness is evaluated by pencil hardness according to JIS-K6894 (tetrafluoroethylene resin-coated film). (3) Adhesive force Adhesive force is evaluated by a line drawing test according to JIS-K6894 (tetrafluoroethylene resin treated film). (4) Non-adhesive property For the non-adhesive property, the contact angle is measured using an automatic contact angle meter (manufactured by Kyowa Interface Science Co., Ltd.), and after washing the surface of the test piece with acetone, the contact angle with ion-exchange water is measured.

[0038]

[Table 3]

From the results shown in Tables 1 and 3, Examples 1 and 2
It can be seen that those coated with the coating agents of Nos. 3 and 3 have both abrasion resistance and non-adhesion. Comparative Example 1, in which the amount of iron oxide powder was small, had insufficient wear resistance.
Comparative Example 2 containing a large amount of iron oxide powder has insufficient adhesion strength. Comparative Example 3 in which the amount of the heat-resistant resin is small has insufficient adhesion strength, and Comparative Example 4 in which the amount of the heat-resistant resin is large has low non-adhesiveness.

[0040]

The coating agent according to the present invention can achieve both abrasion resistance and non-adhesiveness, and the surface of the coating layer is extremely smooth. Further, it is an excellent coating agent that can employ a simple application method such as spray coating. Since the sliding member according to the present invention has the surface coating layer obtained by the above-described coating agent, the sliding portion has a small wear amount and is excellent in durability.

Claims (6)

[Claims] 1. A wear-resistant, non-adhesive coating agent comprising at least a fluorine-based resin, a heat-resistant resin, and iron oxide powder. 2. The wear-resistant and non-adhesive coating agent according to claim 1, wherein the heat-resistant resin is a polyimide resin. 3. The abrasion-resistant non-adhesive coating agent according to claim 2, wherein the polyimide resin is a polyamide-imide resin. 4. The abrasion-resistant and non-adhesive coating agent according to claim 1, wherein the fluorine-based resin is a polytetrafluoroethylene resin. 5. The method according to claim 1, further comprising at least 100 parts by weight of the fluororesin, 100 to 150 parts by weight of the heat-resistant resin, and 5 to 20 parts by weight of iron oxide powder. The wear-resistant and non-adhesive coating agent according to claim 1. 6. A sliding member having a slidable coating layer on a surface of a base material, wherein the slidable coating layer is abrasion resistant according to any one of claims 1 to 5. -A sliding member characterized by being a resin coating layer formed using a non-adhesive coating agent.