JP2002012885A - Water-based lubricant and method for treating surface of metallic material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new water-based lubricant capable of forming a film having excellent sliding characteristics on a surface of a metallic material at a low cost with a low environmental pollution load, and to provide a method for treating the surface by using the lubricant. SOLUTION: This water-based lubricant contains molybdenum disulfide having an average particle diameter of 0.5-10 μm and a water-based resin having a tensile strength at break of >=300 kg/cm2, a tensile elongation at break of <=10% and an average molecular weight of 5,000-50,000. A polyester based-resin or an aqueous urethane resin is preferably used as the water-based resin. The method for treating the surface of the metallic material comprises contacting a clean surface of the metallic material with the lubricant to form a water-based lubricant film layer containing the molybdenum disulfide in an amount of 0.1-5.0 g/m2 as molybdenum and the resin in an amount of 1.0-5.0 g/m2 as carbon, then baking and drying the formed layer at 100-250 deg.C. The surface treatment is preferably applied to the surface of the metallic material which is covered with a crystalline manganese phosphate film having a film thickness of 1-15 μm, a crystal grain diameter of 0.5-30 μm, and a surface roughness (Rz) of 0.5-20 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aqueous lubricant used for forming a film having excellent sliding lubricity on the surface of a metal material, and a method for treating the surface of the lubricant. More specifically, the present invention relates to an aqueous lubricant composed of molybdenum disulfide and a resin having specific properties, and a method for treating a metal material using the same.

[0002]

2. Description of the Related Art Molybdenum disulfide has been used for a long time as a solid lubricant, and is still used for various applications including various automobile parts. From the past, generally, dissolving molybdenum disulfide as a lubricant and polyamideimide as a binder in an organic solvent, spraying and applying the same,
A baking process is employed. However, in recent years, from the viewpoint of global environmental protection, development of an aqueous lubricant that does not use an organic solvent has been strongly desired.

On the other hand, the manganese phosphate treatment was put into practical use in the 1940s as a rust preventive treatment for steel, and thereafter, the manganese phosphate coating was applied as a sliding coating. This is because the material is harder than the other chemical conversion coatings, has excellent abrasion resistance, has good initial conformability, and has a lubricating oil retaining property for retaining lubricating oil on the surface because of being porous. In addition, it is considered that metal contact occurs in a sliding portion that is not subjected to surface treatment, and it is said that the temperature is locally high and high. In such a state, remarkable wear occurs locally at the time of sliding, and the member deteriorates. Therefore, it is also important to prevent direct contact of metal, and it has been found that forming a manganese phosphate film on the surface is effective in preventing direct contact of metal. Has been applied to. However, in recent years, the use conditions (load, etc.) of the sliding member have been
There are increasing demands for stricter requirements and longer life of members is desired. For this reason, in many cases, the conventional manganese phosphate film alone cannot provide sufficient performance.

On the other hand, a method of overcoating manganese phosphate with molybdenum disulfide has been devised in order to improve the tribological properties of the film. For example, in Japanese Patent Publication No. Hei 7-113401 (gear transmission mechanism for vacuum environment), at least the meshing portion of the teeth is formed of alloy tool steel, and a manganese phosphate base treatment layer and a fixed lubricating film are formed on the meshing portion. A gear transmission mechanism for a vacuum environment characterized by having solid lubrication gears formed in order is disclosed, and it is described that the solid lubrication film is preferably formed of molybdenum disulfide. However, there is no description about a binder of a lubricant for forming a solid lubricating film.
Japanese Patent Application Laid-Open No. 9-184079 (wear member) discloses that a manganese phosphate layer is formed on at least the upper and lower surfaces of a base of a pressure ring and an average particle size of 1 to 2 μm is formed in a gap between crystal grains thereof.
A wear-resistant member provided with a lubricating layer in which m molybdenum disulfide is dispersed is disclosed. Although the disclosed method lists polyamideimide, epoxy, polyimide, polytetrafluoroethylene as preferred binders, it does not mention the mechanical properties of the resin. In the examples, polyamideimide is used as a binder, which is presumably using an organic solvent-based coating method.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve these problems of the prior art. Specifically, a film having extremely excellent sliding properties is formed on the surface of a metal material. It is an object of the present invention to provide a novel water-based lubricant formed at low cost and with a low environmental pollution load, and a surface treatment method thereof.

[0006]

Means for Solving the Problems The present inventors have intensively studied means for solving the problems of the prior art. As a result, an aqueous lubricant comprising molybdenum disulfide of a specific particle size and a resin having specific mechanical properties and a surface treatment method using this lubricant, and further from a specific manganese phosphate film layer and a lubricating layer A new method for forming a composite film has been found, and the present invention has been completed.

That is, according to the present invention, the average particle size is 0.5 to
10 μm molybdenum disulfide and breaking strength 300 kg /
cm ² or more, elongation at break of 10% or less and an average molecular weight of 500
A water-based lubricant containing 0 to 50,000 water-based resin. The aqueous resin is preferably a polyester resin or an aqueous urethane resin.
Further, the present invention provides a method in which the lubricant is brought into contact with the surface of a clean metal material so that molybdenum disulfide is converted to molybdenum by 0.1%.
0.1 to 5.0 g / m ² , using carbon as the resin.
A water-based lubricant film layer containing 0 g / m ² was formed.
A surface treatment method for a metal material, wherein baking and drying are performed at 00 to 250 ° C. Further, the present invention provides a method for manufacturing a lubricant, comprising the steps of: applying a lubricant to a metal material surface coated with a crystalline manganese phosphate film having a film thickness of 1 to 15 μm, a crystal grain size of 0.5 to 30 μm, and a surface roughness (Rz) of 0.5 to 20 μm. Contact
0.1-5.0 g of molybdenum disulfide as molybdenum
/ M ² , after forming an aqueous lubricant film layer containing 0.1 to 5.0 g / m ^{2 of} resin as carbon, 100 to 250 ° C.
Baking and drying to form a composite film composed of a manganese phosphate film layer and a lubricating film layer.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. The metal material to which the present invention is applied is not particularly limited, but is mainly applied to steel materials such as carbon steel, chromium steel, chromium molybdenum steel, high carbon chromium steel, aluminum, and aluminum alloy.

The aqueous lubricant of the present invention can be produced by dispersing molybdenum disulfide and an aqueous resin in water. The average particle size of molybdenum disulfide used in the water-based lubricant of the present invention needs to be in the range of 0.5 to 10 μm. By using a material in this range, excellent sliding characteristics can be obtained. If the thickness is less than 0.5 μm, there is no problem in performance, but the cost is undesirably high. On the other hand, if it exceeds 10 μm, dispersion in the lubricant becomes poor, which is not preferable. The water-based resin used in the water-based lubricant of the present invention is a resin that can be used by being dissolved or dispersed in water, for example,
Examples include polyester resin, polyurethane resin, and polyphenol resin. Particularly, a polyester resin or an aqueous urethane resin (dispersion) is preferable. Examples of the polyester-based resin include a polyester resin using a sulfonated product of terephthalic acid or isophthalic acid as a copolymerization component. An aqueous polyurethane resin based on a polyisocyanate such as an isocyanate is exemplified. It is necessary to use a resin having a breaking strength of 300 kg / cm ² or more, a breaking elongation of 10% or less, and an average molecular weight of 5,000 to 50,000. This is because a material having high breaking strength and low elongation has excellent wear resistance. The average molecular weight must be within this range in order to affect the dispersibility of the treating agent.

Next, using the above-mentioned water-based lubricant, a metal material
A method for treating the surface of the above will be described. This metal material
In the surface treatment method, first, the aqueous metal
Molybdenum disulfide is converted to molybdenum by contacting lubricant
0.1-5.0 g / m^Two, Using carbon as the resin.
1 to 5.0 g / m^TwoWater-based lubricant film layer containing
You. Thereafter, baking and drying are performed at 100 to 250 ° C.
As a result of this baking, the molybdenum content is 0.1 to 5.
0 g / m^Two0.1 to 5.0 g / m as carbon^TwoIncluding
A lubricating film is formed on the surface of the metal material. This burning
The amount of each of the molybdenum and carbon after drying is 0.
1g / m^TwoIf it is less than 30, sufficient sliding characteristics cannot be obtained. Ma
In addition, the amount of each of the molybdenum and carbon was 5.
0 g / m ^TwoThere is no problem even if it exceeds, but it is economically preferable
I don't.

The method of bringing the aqueous lubricant into contact with the metal material is not particularly limited, but a dipping method, a spray coating method, or the like can be used. The aqueous lubricant is brought into contact with a stock solution or a diluted processing solution. Further, a surfactant may be used in combination to uniformly apply molybdenum disulfide. The concentration of the molybdenum disulfide and the resin in the treatment liquid is not particularly limited,
Usually, each is preferably about 0.1 to 1%. Concentration 0.1
%, The concentration is low, and unless the number of times of application is increased, a predetermined adhesion amount cannot be obtained. For this reason, the process becomes longer, which is not economically preferable. On the other hand, if it exceeds 1%, the stability of the processing solution becomes poor, which is not preferable.

Thereafter, baking and drying are performed at a temperature of 100 to 250 ° C. to form a lubricating film layer. The purpose of this baking and drying is to blow off the water, to flow the resin used, that is, to soften the resin to make it smoother, and to obtain higher adhesion. It is necessary to More preferably, 150 to
It is in the range of 200 ° C.

When the above metal material surface treatment method is applied to a steel material, it is preferable to form a manganese phosphate film on the surface in advance from the viewpoint of sliding lubricity, adhesion and corrosion resistance. The manganese phosphate film to be formed is preferably controlled to have a film thickness of 1 to 15 μm, a crystal grain size of 0.5 to 30 μm, and a surface roughness (Rz) of 0.5 to 20 μm. When the film thickness is less than 1 μm, the baking resistance becomes low, which is not preferable. Even if the film thickness exceeds 15 μm, there is no difference in performance and it is not economically preferable. If the crystal grain size is less than 0.5 μm, the withstand load is not sufficient,
If it exceeds, the coefficient of friction is undesirably high. If the surface roughness (Rz) is less than 0.5 μm, the adhesion becomes poor, which is not preferable. If it exceeds 20 μm, the surface roughness is large, and the coatability of the lubricating film is poor.

The method of measuring the film thickness, crystal grain size, surface roughness, molybdenum adhesion amount and carbon adhesion amount specified in the present invention will be described. That is, the thickness of the manganese phosphate film is measured by cutting the member after the chemical conversion treatment and observing the cross section with a metallographic microscope. The crystal grain size is measured by observing the surface with a commercially available scanning electron microscope (SEM). The surface roughness is measured using a commercially available surface roughness meter.

Further, the amount of molybdenum adhered is determined by using commercially available fluorescent X
It is quantified by a line analyzer (XRF). A plurality of samples having a known amount of molybdenum and having different amounts of adhesion are measured, and a calibration curve of intensity-adhesion amount is created based on the intensity at this time. Under the same conditions, a sample treated by the surface treatment method of the present invention is cut into an appropriate size (about 3 cm) and measured.
This measured intensity is converted to molybdenum adhesion amount based on the above-mentioned calibration curve. The amount of carbon deposition is measured using a commercially available surface carbon analyzer (TOC). The sample treated by the surface treatment method of the present invention is appropriately sized (20 to
(About 50 cm ² ) to make a sample. The surface carbon analyzer is based on the principle that the temperature of a sample is raised, carbon present on the surface is oxidized and gasified, and this gas is quantified by infrared absorption analysis (IR). The measurement conditions may be any conditions as long as the surface carbon is oxidized and gasified.
It is preferable to measure under the condition of about -5 minutes.

[0016]

EXAMPLES The present invention is described below with reference to several examples, and the usefulness thereof is shown in comparison with comparative examples. [Materials] The following steel materials were treated. Flat plate: S45C dimensions; 30 mm x 80 mm, thickness 1 m
m Sliding lubrication test piece (SRV): SUJ2 φ24 × 8 mm [Pretreatment] Cleaning treatment: 60 ° C. using a 2% aqueous solution of a commercially available detergent (registered trademark Fine Cleaner 4360: manufactured by Nippon Pa-Calizing Co., Ltd.) Soaked for -3 minutes, then rinsed with tap water for 30 seconds to clean. Manganese phosphate treatment: After washing treatment, 0.3 of commercially available surface conditioner [registered trademark Preparen 55 (Example 3) or Preparen VM (Example 4 and Comparative Example 2): both manufactured by Nippon Parkerizing Co., Ltd.] % Aqueous solution of manganese phosphate (registered trademark, Parphos M1A: manufactured by Nippon Parkerizing Co., Ltd.), followed by immersion treatment at 95 ° C. for 5 minutes. afterwards,
Wash-dry.

Example 1 The following surface treatment liquid 1 was applied to the above-mentioned washed steel material, followed by baking at 160 ° C. for 10 minutes. Surface treatment liquid 1 Molybdenum disulfide: Average particle size 2.0 μm Water-based resin: Polyester resin Resin breaking strength: 350 kg / cm ² Resin elongation: 2% Average molecular weight of resin: 10,000 It was prepared by dispersing molybdenum disulfide powder in a dispersion.

Example 2 The following surface treatment liquid 2 was applied to the steel material subjected to the cleaning treatment, and then baked at 200 ° C. for 10 minutes. Surface treatment liquid 2 Molybdenum disulfide (average particle size): 4.0 μm Water-based resin: Polyester resin Resin breaking strength: 320 kg / cm ² Resin elongation: 1% Average molecular weight of resin: 12000 This treatment liquid 2 is a polyester resin. Was prepared by dispersing molybdenum disulfide powder in an aqueous dispersion of

Example 3 The manganese phosphate treatment was applied to the washed steel material, and then a surface treatment liquid 3 was applied.
Baking was performed at 5 ° C. for 5 minutes. Surface treatment liquid 3 Molybdenum disulfide (average particle size): 20 μm Aqueous resin: aqueous urethane resin Resin breaking strength: 310 kg / cm ² Resin elongation: 5% Average molecular weight of resin: 8000 This treatment liquid 3 is an aqueous solution of urethane resin. It was prepared by dispersing molybdenum disulfide powder in a dispersion.

Example 4 The above-mentioned washed steel material was heated to 65 ° C. and immersed in the following surface treatment liquid 4 for 10 minutes. Then, it was washed with water and dried. Thereafter, the surface treatment liquid 3 used in Example 3 was applied and baked at 180 ° C. for 10 minutes. Surface treatment liquid 4 Molybdenum disulfide (average particle size): 15 μm Aqueous resin: aqueous urethane resin Resin breaking strength: 350 kg / cm ² Resin elongation: 3% Average molecular weight of resin: 15000 This treatment liquid 4 is an aqueous urethane resin. It was prepared by dispersing molybdenum disulfide powder in a dispersion.

Comparative Example 1 The surface treatment was not performed after the above-described cleaning treatment. Comparative Example 2 The surface treatment was not performed after the cleaning treatment and the manganese phosphate treatment.

In Examples 1 to 4 and Comparative Examples 1 and 2, the coating thickness, particle size and roughness of the manganese phosphate layer, the amount of molybdenum and carbon in the lubricating coating layer formed by the surface treatment, and the sliding The lubrication evaluation is shown in Table 1. The sliding lubrication test was performed by the following method. [Sliding lubrication test] Evaluation was performed using a commercially available SRV tester. Treated test specimen and untreated steel ball (SUJ2, diameter 1
0 mm), and slid with no load with a load of 100 N, a frequency of 50 Hz, and an amplitude of 2 mm. The coefficient of friction was measured and the time to reach a coefficient of friction of 0.6 was measured. The longer this time, the better the lubricity. As shown in Table 1, it can be seen that excellent lubricity was obtained by the present invention.

[0023]

[Table 1]

[0024]

According to the present invention, an extremely excellent sliding lubrication is provided on the surface of a metal material by preparing an aqueous lubricant using a specific aqueous resin and using the aqueous lubricant for the surface treatment of the metal material. An excellent effect is obtained that a film having characteristics can be formed at low cost and with a low environmental pollution load.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C23C 22/83 C23C 22/83 26/00 26/00 A 28/00 28/00 Z // C10N 10: 12 C10N 10:12 20:00 20:00 Z 20:04 20:04 20:06 20:06 Z 40:20 40:20 Z 50:02 50:02 (72) Inventor Masayuki Yoshida Nihonbashi, Chuo-ku, Tokyo 1-15-1 F-Term in Nippon Parkerizing Co., Ltd. (Reference) 4H104 AA01C AA19A CB13A CE13A EA01A EA03A EA08A EA17A FA06 PA21 QA01 QA08 4K026 AA02 AA09 BA05 BB04 CA11 DA03 EA08 EB05 EB11 CA05 BC03 BA02 BA02 BA03

Claims (4)

[Claims] 1. Molybdenum disulfide having an average particle size of 0.5 to 10 μm, a breaking strength of 300 kg / cm ² or more, and a breaking elongation of 1
An aqueous lubricant containing an aqueous resin having an average molecular weight of 5,000 to 50,000 at 0% or less. 2. The aqueous lubricant according to claim 1, wherein the aqueous resin is a polyester resin or an aqueous urethane resin. 3. An aqueous lubricant according to claim 1 or 2 is brought into contact with the surface of a clean metal material to obtain 0.1 to 5.0 g / m ^{2 of} molybdenum disulfide as molybdenum and 0.1 to 5.0 g / m ² of resin as carbon. A surface treatment method for a metal material, comprising forming a water-based lubricant film layer containing 1 to 5.0 g / m ² , followed by baking and drying at 100 to 250 ° C. 4. A film thickness of 1 to 15 μm and a crystal grain size of 0.5 to 3
A water-based lubricant according to claim 1 or 2 is brought into contact with a metal surface coated with a crystalline manganese phosphate film having a thickness of 0 μm and a surface roughness (Rz) of 0.5 to 20 μm to convert molybdenum disulfide into molybdenum. 0.1 to 5.0 g / m ^2, after forming a water-based lubricant coating layer comprising 0.1 to 5.0 g / m ² resin as carbon, perform baking and drying at 100 to 250 ° C., manganese phosphate A surface treatment method for a metal material, comprising forming a composite film comprising a film layer and a lubricating film layer.