JP4783124B2 - A method for forming a lubricating film. - Google Patents

Description

The present invention relates to a method of forming a coating having excellent lubricating properties to an aluminum alloy or magnesium alloy surface, in particular, it relates to a method for reducing the sliding frictional resistance of the alloy surface.

  As a method for imparting lubricity to the anodized film of an aluminum alloy, the following method has been conventionally proposed.

  There is a method of impregnating the anodic oxide film with a liquid or wax-like lubricating oil, but it is easily affected by other solvents and oils that come into contact with it, and there is a concern about contamination on the periphery. Further, as a solid lubricant, there is molybdenum disulfide (Japanese Patent Laid-Open No. 56-130489) on an anodized film, but the initial sliding friction coefficient (0.2 to 0.3) is high, and durability. It is scarce. The method of impregnating polytetrafluoroethylene into the pores of a hard oxide film taking advantage of the properties of polytetrafluoroethylene (Japanese Patent Publication No. 52-39059) is sufficient for the penetration of polytetrafluoroethylene particles into the pores. is not. As a method for improving the adhesion, there has been proposed a method for forming a lubricating film by electrochemically or chemically adsorbing polytetrafluoroethylene or drying and then sliding it with a counterpart material (Japanese Patent Laid-Open No. 5-51794). However, the adhesion to the anodized surface is not sufficient, and consideration is required for handling until the heat of sliding friction is generated. Further, the treatment liquid needs to be heated at 40 to 80 ° C., and there is a concern about dispersion stability of polytetrafluoroethylene in the treatment liquid, and further, an apparatus and energy for heating the bath liquid are necessary.

JP-A-56-130489 Japanese Patent Publication No.52-39059 JP-A-5-51794

  Sophistication, high performance, and functionalization of the technology are required, and the conventional method of impregnating or adsorbing fine particles of polytetrafluoroethylene into the anodic oxide film is the adhesion between the anodic oxide film and polytetrafluoroethylene. It is not sufficient, and accordingly, the durability is not sufficient, the use is limited, and the improvement is demanded.

The present invention, on the surface of aluminum alloy or magnesium alloy anodized film, firmly to and uniformly fix the fine particles of polytetrafluoroethylene by a reactive surfactant, excellent sliding lubricity, durability It is an object of the present invention to provide a method for forming a film. This also provides a lightweight, wear-resistant article and chemical-resistant article.

The present invention is a method of forming a film having excellent lubricity aluminum alloy or and magnesium alloy surfaces.
That is, a first aspect of the invention, after forming an anodized film on an aluminum alloy or magnesium alloy surface, the aqueous dispersion of polytetrafluoroethylene containing reactive surfactant, electrochemical or chemical The method according to claim 2 uses any one or more of a silane coupling agent and an organic titanium compound as a reactive surfactant. The method for forming a lubricating film according to claim 1, wherein the invention according to claim 3 is characterized in that the object to be treated is an anode and is electrochemically treated at a DC voltage of 5 to 200 volts. The method for forming a lubricating film according to claim 1 or 2, wherein the invention according to claim 4 is in contact with the dispersion at 5 to 40 ° C. and chemically treated. Contract The method for forming a lubricating film according to any one of Items 1, 2, or 3, wherein the invention according to Claim 5 is characterized by washing with water after the treatment according to any one of Items 1 to 4. The method for forming a lubricating film according to any one of 2, 3, and 4.

Further More specifically, after forming an anodized film on an aluminum alloy or magnesium alloy surface in the normal manner, without the sealing treatment, polytetrafluoroethylene particles containing reactive surfactant In this method, polytetrafluoroethylene particles are adsorbed to form a film by dipping, pouring, and in contact with a suspended aqueous solution, by showering or coating.

  Furthermore, a method for forming a uniform and strong film is a method in which a metal to be treated is used as an anode and electrochemically deposited.

  In the present invention, fine particles of polytetrafluoroethylene can be uniformly attached to the anodized film by the action of a surfactant that is adsorbed and reactive on the metal surface.

  The anodic oxide film used in the present invention is not particularly limited, but is preferably a film satisfying the mechanical friction strength required by the article to be treated. The film thickness is 5 to 100 μm, and a hard anodic oxide film is suitable.

  After the anodic oxide film treatment, in order to remove excess treatment liquid, it is usually washed with water and then treated with the dispersion solution of the present invention.

  Dyeing, secondary electrolytic treatment, etc. can be performed after the anodizing treatment.

  Furthermore, the anodized film treatment and the film after the post-treatment are preferably unsealed or electrically conductive, and particularly when deposited electrochemically from the dispersion solution of the present invention, without sealing treatment, Immersed directly and processed electrochemically.

  However, it does not prevent chemical adsorption by the immersion, shower or spray treatment with the dispersion of the present invention after the sealing treatment.

  As the reactive activator, a silane coupling agent or an organic titanium compound can be used.

  The silane coupling agent that can be used in the present invention has a reactive functional group X chemically bonded to an organic resin and a reactive group Y chemically bonded to an inorganic material in the same molecule as follows. 1 is an organosilicon compound represented by the general formula 1 and is also called carbon functional silane.

(However, X is a functional group having reactivity such as vinyl group, acryloyl group, methacryloyl group, amino group, isocyanato group, mercapto group, epoxy group, sulfide group, and alkyl group and fluorine-containing alkyl group, and R is propyl. : —CH ₂ CH ₂ CH ₂ —, and R without X is a vinyltrialkoxysilane bonded directly to Si, Y is a hydrolyzable alkoxy group, chlorine, and a typical one is a methoxy group: -OCH _3, an ethoxy group: _-OC 2 _{H 5,} isopropoxy:. -OCH _{(CH 3) 2,} etc. Further, m is a positive integer of 1 or more, n represents an 4 or more positive integer. )

  The film made of the fine particles of polytetrafluoroethylene obtained by the method of the present invention is firmly attached to the anodized film, maintains a low initial frictional resistance up to a long sliding distance, and has a durable film. Can be provided.

The organic titanium compound that can be used in the present invention is tetraalkoxytitanium: Ti (OR) _4, which is an ester of orthotitanic acid: Ti (OH) ₄ , and derivatives thereof.

  The particle diameter of polytetrafluoroethylene that can be used in the present invention is preferably 1 μm or less. Although particles having a particle size of 0.1 μm or more are commercially available, in order to put polytetrafluoroethylene on the surface of the aluminum anodic oxide film by electrophoresis, etc. The particle diameter is preferably 1 μm or less.

  The composition of the dispersion treatment liquid used in the present invention is preferably 1 to 20% by weight of polytetrafluoroethylene fine particles and 0.01 to 2% by weight of a reactive surfactant. If the polytetrafluoroethylene fine particles are less than 1% by weight, the lubricating performance is insufficient. If the polytetrafluoroethylene fine particles are more than 20% by weight, the polytetrafluoroethylene fine particles are excessively adhered to the surface, and the lubricity is reduced. If the reactive surfactant is less than 0.01% by weight, the particles are easy to peel off even if attached, and if it exceeds 2% by weight, it is difficult to adhere.

  As an aid for dispersion of polytetrafluoroethylene fine particles, anionic, cationic, zwitterionic and nonionic surfactants, and thermoplastics such as vinyl alcohol, acrylic acid, acrylamide resins and copolymers with other monomers and cellulose A polymer resin can also be used.

  The pH of the dispersion treatment liquid is preferably in the range of 4 to 10, and the stability of the dispersion liquid is poor in other regions. Adjust pH with inorganic acids such as sulfuric acid, phosphoric acid, nitric acid, boric acid and hydrofluoric acid, organic acids such as oxalic acid, citric acid, tartaric acid and malic acid, as well as ammonia, caustic soda and caustic potash. Can do.

  The temperature of the treatment liquid of the present invention is 5 to 40 ° C., preferably room temperature (15 to 25 ° C.) in the electrochemical treatment. In dipping, showering, spraying, and coating treatment, room temperature to 40 ° C. is preferable.

  In the electrochemical treatment, a current is applied at a direct current of 5 to 200 V for 0.5 to 5 minutes. Depending on the thickness of the anodized film, it is processed according to the appropriate conditions.

  In the dipping method or the like, there is no time limit, but the treatment is preferably performed for 0.5 to 30 minutes.

  After the treatment with the dispersion treatment liquid, the excess treatment liquid can be removed by washing with water after draining, if necessary. Washing with water can be performed by dipping or mist spraying, and hot water washing at 40 to 60 ° C. can be used from the viewpoint of drying workability.

  Treated with a dispersion treatment liquid, drained or washed with water, and then drained and dried. Although there is no restriction | limiting of a drying temperature, 40-130 degreeC warm hot-air drying is preferable.

Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples of the anodized film.
[Method of treating anodized film]

The surface of the aluminum 5052 alloy is degreased / cleaned, etched, pickled / desmutted by conventional means to remove the oxide film and fine scratches on the surface of the metal to be processed, and the surface is made uniform. It is immersed in a mixed acid electrolyte solution of 20% by weight and 2% by weight of oxalic acid at 15 ° C., electrolyzed with a direct current of 3 A / dm ² for about 10 minutes and 30 minutes, washed with water, and 10 μm and 30 μm hard anodic oxide films are formed. Obtained.

The surface of magnesium AZ91D alloy is degreased, washed, etched with 5% citric acid / oxalic acid mixed solution, washed with 10% nitric acid, 30% acid ammonium fluoride, 10% sodium dichromate, 85% phosphorus It was immersed in an electrolyte solution of 9% by volume of acid at 80 ° C., and electrolysis was performed at a current density of 2.5 A / dm ² with direct current for 30 minutes.
[Method for Adjusting Dispersion Treatment Liquid of the Present Invention]

  Treatment liquid Dispersion treatment liquid 1 used in the present invention comprises 50 g of polytetrafluoroethylene fine particles of about 0.5 μm or less, deionized water containing 0.5 g of nonionic surfactant (5 mol of ethylene oxide) and 0.5 g of anionic surfactant. After kneading with 50 g, suspended and dispersed in about 400 ml of deionized water, and separately adding 2.5 g of 3-glycidoxypropyltrimethoxysilane to a solution of 1 g of oxalic acid dissolved in 500 ml of deionized water The solution pH was adjusted to 6-7 using aqueous ammonia and oxalic acid.

1. Treatment liquid Further, as the dispersion treatment liquid 2 used in the present invention, 3 g of di-n-butoxy bis (triethanolaminato) titanium: Ti (OCH ₂ ) prepared in advance with 50 g of polytetrafluoroethylene fine particles of about 0.5 μm or less. Deionized water containing CH ₂ CH ₂ CH ₃ ) ₂ [OC ₂ H ₄ N (C ₂ H ₄ OH) ₂ ], 0.5 g nonionic surfactant (5 mol ethylene oxide) and 0.5 g anionic surfactant After kneading with 20 g, the solution was poured, suspended and dispersed in about 900 ml of an aqueous solution with deionized water, and the solution pH was adjusted to 9 using aqueous ammonia.
[Performance evaluation method]

The performance evaluation method uses a ball-on-desk type wear tester based on JIS R 1613-1993, and uses friction load 30g, 50g, 100g, 150g, mating material 5mmφ SUJ2 steel ball, and expresses it by sliding distance and friction coefficient did. An evaluation on the examples and an evaluation on the comparative examples when the anodized film of aluminum or magnesium alloy was subjected to a predetermined treatment and a friction test was performed.
[Examples 1, 2 and 3]

Using the aluminum alloy (Examples 1 and 2) and the magnesium alloy (Example 3) of about 30 μm anodized film and the prepared dispersion treatment liquid 1, an anodized film is arranged on the anode side, and a stainless steel plate Table 1 shows the results of performance evaluation after electrolysis at 30 V direct current for 3 minutes to form a polytetrafluoroethylene film with a dryer at about 60 ° C.
[Example 4]

About 30 μm of the anodized film of the aluminum alloy is immersed in the dispersion treatment liquid 2 prepared at 25 ° C., the anodized film is arranged on the anode side, and the stainless steel plate is used as a cathode, and electrolysis is performed at 90 V DC for 3 minutes. Table 1 shows the results of performance evaluation after forming a polytetrafluoroethylene film and drying with a dryer at about 60 ° C. Table 1 also describes specific details of anodic oxidation.
[Example 5]

Table 1 shows the results of performance evaluation of an anodized film of about 30 μm of the aluminum alloy immersed in the prepared dispersion treatment liquid 1 at 40 ° C. for 5 minutes and dried with warm air.
[Example 6]

About 30 μm of the anodized film of the aluminum alloy is immersed in the dispersion treatment liquid 1 prepared at 25 ° C., the anodized film is arranged on the anode side, and the stainless steel plate is used as a cathode, and electrolysis is performed at 90 V DC for 3 minutes. Table 1 shows the results of performance evaluation after forming a polytetrafluoroethylene film, dipping in deionized water, removing excess treatment liquid, and drying with a warm air dryer at about 60 ° C. Indicated.
[Example 7]

About 30 μm of the anodic oxide film of the aluminum alloy was immersed in the prepared dispersion treatment liquid 1 at 40 ° C. for 5 minutes, and then the excess dispersion treatment liquid 1 was removed by mist spraying. The results of drying and performance evaluation are shown in Table 1.
[Comparative example]

As a comparative example, only an anodized film of 10 μm aluminum alloy in comparative example 1, 30 μm aluminum alloy in comparative example 2, 20 μm magnesium alloy in comparative example 3, and dispersion of polytetrafluoroethylene containing no reactive surfactant The results when using the liquid are shown in Table 1.
[Method for adjusting dispersion processing liquid of comparative example]

As a dispersion treatment liquid containing no reactive surfactant of Comparative Example, 50 g of polytetrafluoroethylene fine particles of about 0.5 μm or less, 0.5 g of nonionic surfactant (5 mol of ethylene oxide) and anionic surfactant 0. After kneading with 50 g of deionized water containing 5 g, suspended in and dispersed in about 400 ml of deionized water, and separately, a solution in which 1 g of oxalic acid was dissolved in 500 ml of deionized water was adjusted to a solution pH of 8 using ammonia water. .
[Comparative Examples 1, 2, and 3]

After forming the anodized film, the performance of the film immersed in the dispersion treatment liquid of the comparative example and electrolyzed for 3 minutes at a direct current of 30 V is, as shown in Table 1, rapidly increased as the sliding distance increases. An increase is observed.
[Comparative Example 4]

  Further, when the excess treatment liquid was washed, the polytetrafluoroethylene peeled off, and it was difficult to obtain a uniform film, and the sliding friction coefficient varied depending on the position of the article to be treated.

Claims (5)

After forming the anodic oxide film on an aluminum alloy or magnesium alloy surface, it features from an aqueous dispersion of polytetrafluoroethylene containing reactive surfactant, electrochemical or chemically adsorbed, by drying A method for forming a lubricating film.   The method for forming a lubricating film according to claim 1, wherein any one or more of a silane coupling agent and an organic titanium compound is used as the reactive surfactant.   3. The method of forming a lubricating film according to claim 1, wherein the object to be treated is an anode and is electrochemically treated at a DC voltage of 5 to 200 volts.   The method for forming a lubricating film according to any one of claims 1, 2, and 3, wherein the dispersion is in contact with the dispersion at 5 to 40 ° C and chemically treated.   The method for forming a lubricating film according to any one of claims 1, 2, 3 and 4, wherein the treatment is carried out according to any one of claims 1 to 4 and then washed with water.