JPS6234360B2 - - Google Patents

Description

[Detailed description of the invention]

This invention applies to rolling, forging or drawing of iron,
The present invention relates to a film-forming high-temperature lubricant composition used in hot working of various metals and alloys, such as extrusion of aluminum and copper, drawing of tungsten and molybdenum, etc. Conventionally, lubricant compositions of this type include lubricating oils, greases, or mixtures thereof with solid lubricants such as graphite powder or tungsten dioxide, or alkali metal sulfates, borates, potassium chloride, and sodium triacetate. An aqueous dispersion of a fine powder mixture consisting of graphite powder and an auxiliary agent added as necessary is known. However, the former is thermally unstable and decomposes during use, which has a negative impact on tools and workpieces, and the oil and oil decomposition products can seriously contaminate the working environment. Although the latter method does not have the same problems as the former method, it cannot be said that it exhibits satisfactory lubrication performance, especially in the production of seamless steel pipes. Therefore, the present inventors first developed a high-temperature lubricant mainly consisting of graphite powder and a plant-based polymer that can be dissolved or dispersed in water, as a solution to the problems with conventional lubricant compositions. (Japanese Patent Application No. 56-147297). Although this lubricant composition has achieved some success in that it does not contaminate the working environment and exhibits excellent lubrication performance at high temperatures, the water resistance of the lubricant film formed on metal surfaces has been limited. Unfortunately, for this reason, it is necessary to prevent water such as roll cooling water from leaking onto the lubricating coating at the work site, and if water leaks by mistake, the lubricating coating can easily wash off, peel off, or cause damage to the lubricating coating. There was a problem that the coating film thickness became uneven and its lubricating performance deteriorated, making it extremely difficult to use. The present invention was invented in view of this point of view, and aims to integrate graphite, resin, and water by using a plant-based polymer as a main ingredient, and improves the formability of a coating film.
A high-temperature lubricant that maintains workability, improves compatibility with the coated material by using synthetic polymers, and exhibits better performance, and forms a coating film with excellent water resistance. A composition is provided. That is, the present invention uses graphite powder of 50 to 94% by weight.
and 9 to 40% by weight of water-soluble or water-based plant-based polymer.
A film-forming high-temperature lubricant composition which further contains 1 to 20% by weight of a water-soluble or water-based plant-based polymer, and which is used as an aqueous lubricant dispersion by dispersing it in water. be. The graphite powder used in this invention may be natural or synthetic.
In addition, the particle size of this graphite powder is usually
Those with an average particle size of 100μ or less and a purity of at least 75% are used, of which an average particle size of 0.3 to 30
μ is preferable. Examples of water-soluble or water-dispersible plant polymers include starch and starch derivatives such as methyl starch, ethyl starch, acetyl starch, allyl starch, carboxymethyl starch, dialdehyde starch, oxidized starch, and modified starch, and amylose. and amylopectin and its derivatives such as amylose triacetate, dextrin and its derivatives, agar, cellulose derivatives such as cellulose ether, carboxymethyl cellulose, and cellulose xanthate, polysaccharides, polysaccharides such as gum arabic, guar gum, and gum substances, etc. can be mentioned. Starch systems consisting of starch, amylose, amylopectin, dextrin, and derivatives thereof are particularly preferred from the viewpoint of film-forming ability. These plant-based polymers are
They may be used alone or in combination of two or more. Furthermore, examples of water-soluble or water-dispersible synthetic polymers used in the present invention include liquid epoxy resins, liquid phenolic resins, liquid silicone resins, liquid alkyd resins, polyethylene glycol, polyethylene oxide, polypropylene oxide, and water-soluble modified polymers. Polyester resins, acrylic resins such as acrylic acid-butyl acrylate copolymers and acrylic acid-ethylene copolymers, styrene resins such as styrene-methyl methacrylate copolymers, and ethylene-vinyl acetate copolymers. Examples include vinyl acetate resin, liquid polyisobutylene, and the like. Among these, preferred are liquid epoxy resin, liquid phenol resin, polyethylene glycol, and ethylene glycol.
Examples include vinyl acetate copolymers, liquid alkyd resins, and modified polyester resins. Resins such as liquid epoxy resins, which cannot be dispersed in water alone, but which can be uniformly dispersed in a graphite suspension solution such as the present system, also fall within the category of water-dispersible synthetic polymers in the present invention. Furthermore, in the present invention, some plant-based polymers rot if left for a long period of time, so it is preferable to incorporate a preservative such as formaldehyde or ethyl paraoxybenzoate. The blending ratio of the film-forming high-temperature lubricant composition of the present invention is usually 50 to 90% by weight of graphite powder, 9 to 40% by weight of vegetable polymer, and 1 to 20% by weight of synthetic polymer, preferably , 60 to 85% by weight of graphite powder, 10 to 30% by weight of vegetable polymer, and 3 to 10% by weight of synthetic polymer. If the graphite powder content is less than 50% by weight, the desired lubrication performance cannot be obtained, and if it is more than 90% by weight, the film strength is insufficient and the desired lubrication performance cannot be obtained. Furthermore, if the amount of the plant-based polymer is less than 9% by weight, the uniformity of the film will be poor, and if it is more than 40% by weight, the strength of the film will be poor and the lubricating performance will deteriorate. Furthermore, if the synthetic polymer content is less than 1% by weight, the water resistance will be poor, and if it is more than 20% by weight, although the coating strength will be strong, the desired lubrication performance will not be obtained. The high temperature lubricant composition of the present invention is used as an aqueous lubricant dispersion by dispersing it in water, and the solid content concentration during use is usually 5 to 35% by weight, preferably 10 to 30% by weight. Adjust within the range of %. In addition, the solid content concentration may be adjusted, for example, once to a solid content concentration of 35 to 50% by weight, and then diluted at the time of use to a solid content concentration of 5 to 35% by weight. If the solid content concentration is too low, the drying time becomes long or the thickness of the formed coating film becomes thin, making it impossible to obtain good lubrication performance, and if the solid content concentration is too high, it becomes difficult to coat. The method for using the aqueous lubricant dispersion prepared in this way is to apply the aqueous lubricant dispersion to the surface of the metal to be hot-worked or to the surface of tools such as mandrels, dies, rolls, etc. by normal means. After drying this and forming a film on the surface of these metals and tools, hot working is performed. In addition, in the film-forming high-temperature lubricant composition of the present invention, conventionally known third components such as film stabilizers and rust inhibitors may be added to the composition in advance or when preparing the aqueous lubricant dispersion. It is also possible to add additives such as additives, antioxidants, surfactants, emulsifiers, extreme pressure agents, etc., and provide each characteristic with these additives. According to the present invention, by using a synthetic polymer in addition to a vegetable polymer, it is possible to enhance the lubricating performance of the lubricating film formed on the metal surface, and also to improve its water resistance. Extremely easy to handle. Hereinafter, the present invention will be specifically described based on Examples and Comparative Examples. Examples 1 to 8 and Comparative Examples 1 to 3 A lubricant composition was prepared by blending graphite powder, a vegetable polymer, and a synthetic polymer in the proportions shown in the table. A lubricant aqueous dispersion was prepared by dispersing the lubricant compositions of each example and each comparative example in water to a solid content concentration of 23% by weight, and this aqueous lubricant dispersion was heated to 200°C. It was spray coated onto a test piece (material: SKD-61) to form a lubricating film with a thickness of 60 μm on the surface of the test piece. This test piece was fixed in a friction and wear tester, and the temperature of the rolled rotating test piece was measured while being pressed against the test piece with lubricated surface pressure (sliding surface pressure) of 0.2 Kgf/mm ² and 19.5 Kgf/ ^mm 2. Relative sliding speed at 1000℃
The friction coefficient under the condition of 1.5 m/s was determined. In addition, a method of spraying the lubricant aqueous dispersion prepared for the lubricant compositions of each Example and each Comparative Example onto a 50 mmφ x 150 mm SUS round bar heated to 200°C, and then pouring tap water after 10 seconds. The water resistance of the lubricating coating film formed was investigated. The results are shown in the table, and in each example, not only the coefficient of friction was small and the lubrication performance was excellent, but the water resistance of the coating film was also good.

【table】

Claims (1)

[Scope of Claims] 1 Mainly composed of 50 to 90% by weight of graphite powder and 9 to 40% by weight of a water-soluble or water-dispersible vegetable polymer, and further 1 to 4% by weight of a water-soluble or water-dispersible synthetic polymer. A film-forming high-temperature lubricant composition containing 20% by weight and characterized in that it is used as an aqueous lubricant dispersion by dispersing it in water. 2. The film-forming high-temperature product according to claim 1, wherein the plant-based polymer is one or a combination of two or more selected from the group consisting of starch, amylose, amylopectin, dextrin, derivatives thereof, and guar gum. Lubricant composition. 3. Claim No. 3 in which the synthetic polymer is one or a combination of two or more selected from the group consisting of epoxy resin, phenolic resin, alkyd resin, polyethylene glycol, ethylene-vinyl acetate copolymer, and modified polyester resin. The film-forming high-temperature lubricant composition according to item 1.