CN101543814A - Method for preparing composite organic protective film on surface of steel - Google Patents

Abstract

The invention discloses a method for preparing a composite organic protective film on the steel surface, which belongs to the technical field of steel surface protection. First, mix and stir the water-based epoxy resin emulsion, water or water-based color paste evenly to make a water-based epoxy resin film-forming liquid for later use; add dispersants and anti-friction, corrosion-resistant, and heat-resistant materials, and then perform film formation with residual heat of the workpiece , heat the steel workpiece, keep it warm to heat the workpiece thoroughly, take out the workpiece and immerse it in the water-based epoxy resin film-forming liquid pool, stay for 5-30 seconds, take it out and heat it to dry, or reheat the steel workpiece that has been formed with a layer of protective film , heat preservation, take out the workpiece to cool in the air or water, and form a composite organic protective film on the surface of the steel workpiece. The composite organic protective film prepared by the invention has high heat resistance and corrosion resistance, and the friction coefficient is greatly reduced. The protective film has the characteristics of not sticking to water, which improves the various properties of the protective film. It has a strong bonding force with steel materials and does not peel off the protective film, so it is widely used.

Description

Preparation method of composite organic protective film on steel surface

technical field

The invention belongs to the technical field of steel surface protection, in particular to a method for preparing a composite organic protective film on the steel surface capable of heat resistance, corrosion resistance and low friction coefficient.

Background technique

In order to prevent corrosion and rust of steel parts and increase the beauty of parts, the traditional methods have been using alkaline blackening process, painting, spraying and other processes.

There are many methods and types of protection and decoration on the surface of steel materials, and they are widely used. There are electroplating using electrochemical reactions; there are blackening and phosphating using oxidation reactions. There are also hot-dip metallization (such as hot-dip zinc, hot-dip aluminum, etc.) and dip coating and spraying of various paints using physical metallurgical methods. The iron and steel materials used in some special working conditions can also use physical and chemical methods of vapor deposition, cold and thermal spraying of metals and metal compounds and plastics. High-temperature chemical infiltration and ion implantation of certain elements such as nitrogen, silicon, aluminum, etc. are also used in some tools, molds and some parts that require wear resistance and corrosion resistance. These processes generally have the disadvantages of cumbersome operation, high labor intensity, high production cost, serious environmental pollution, and high cost of three wastes treatment.

Iron and steel antirust (macromolecule) blackening (Chinese scientific and technological achievements) that uses the waste heat of the steel workpiece itself to form an organic protective film has been studied, such as: JH-300, JH-200 steel blackening agent is used for iron and steel surface blackening above 200 ° C. black. According to the thermal reaction polymerization mechanism, a layer of black polymer protective film is deposited on the surface, which has strong antirust ability. 2-3 drops of 3% copper sulfate solution, no rose-colored erythema in 10 minutes; 3% sodium chloride solution for 30 minutes, no rust spots; 5% oxalic acid solution, 2-3 drops, 8 minutes, no corrosion spots instead of alkaline blackening . The organic protective film prepared by this method is thin, single and loose. Although it has a certain anti-corrosion effect, it is generally only used to replace high-temperature alkaline blackening or normal temperature blackening, and is used for workpiece inventory protection. Although the heat resistance and corrosion resistance are improved by the two times of film formation using residual heat, the friction reduction property is not high.

Therefore, before the present invention, since the waste heat of the iron and steel workpiece itself cannot be used to obtain a dense, heat-resistant, friction-reducing, and water-free protective film, the performance of the organic protective film is greatly affected, resulting in its lack of heat resistance, corrosion resistance, and requirements. The basis for practical applications with low coefficients of friction.

Contents of the invention

The object of the present invention is to provide a kind of preparation method of the composite organic protective film on iron and steel surface, it is characterized in that, comprises the steps:

1) Mix and stir the water-based epoxy resin emulsion, water or water-based color paste evenly to make a water-based epoxy resin film-forming liquid for later use.

2) add dispersant and anti-friction, corrosion resistance, heat-resistant material in water-based epoxy resin film-forming liquid, wherein, the consumption of dispersant is selected as water-based epoxy resin film-forming liquid by weight and number ratio: dispersant=10 :0.05—10:0.5.

3) Execution of film formation by waste heat of the workpiece

Heat the iron and steel workpiece in the heating furnace 1 to 150°C-600°C, keep warm to heat the workpiece thoroughly, take out the workpiece and immerse it in the water-based epoxy resin film-forming liquid pool containing 1%--10%, stay for 5-30 seconds and take it out , heat and dry at 60-100°C in the heating furnace 2, or reheat the steel workpiece with a layer of protective film to 150°C-350°C, keep it warm for 20-60 minutes, take out the workpiece and cool it in air or water, A composite organic protective film is formed on the surface of steel workpieces.

The dispersant is trisodium phosphate.

The friction-reducing, corrosion-resistant and heat-resistant materials are water-based polytetrafluoroethylene and organic bentonite.

The polytetrafluoroethylene addition is controlled in water-based epoxy resin film-forming solution by weight and number of parts: water-based polytetrafluoroethylene=10:1-10:5; the organic bentonite addition is controlled in water-based epoxy resin by weight and number of ratio Oxygen resin film-forming solution: organic bentonite powder = 10:0.1—10:2.

The water-based color paste is an inorganic colorant, the particle size of the inorganic powder is in the range of 1000-2000 mesh, and the inorganic colorant includes carbon black, iron oxide black, and titanium dioxide;

The added amount of the inorganic colorant is controlled in the water-based epoxy resin film-forming liquid by weight and number: inorganic colorant=10:0.2-10:0.3, and the inorganic colorant is uniform in the water-based epoxy resin film-forming liquid distributed.

The beneficial effect of the present invention is that the composite organic protective film prepared by the present invention is due to the addition of heat-resistant, corrosion-resistant, and friction-reducing materials "bentonite" and "polytetrafluoroethylene resin" in the water-soluble epoxy resin, so that the formed film layer The heat resistance and corrosion resistance are greatly improved, and the friction coefficient is greatly reduced. By heating and drying after film formation, that is

It can improve the combination of various components in the protective film, and can also improve the compactness of the film. Due to the addition of polytetrafluoroethylene resin, the protective film has the characteristics of not sticking to water, which greatly improves the various properties of the protective film. It has strong bonding force and high corrosion resistance with steel materials, and the protective film will not peel off.

Experiments show that the film layer will not be damaged if kept at 360°C for 2 hours, soaked in 5% hydrochloric acid solution for 3 days without peeling, and its corrosion point is less than 1/square centimeter, soaked in 5% sodium hydroxide solution for 5 days No abnormality. The steel organic protective film of the present invention can be applied to the protection and decoration of various steel parts such as various fasteners, spring parts, various mechanical parts and other engineering steel components, thereby greatly expanding the scope of the steel organic protective film. scope of application.

Description of drawings

Figure 1 is a schematic diagram of the structure of a steel surface covered with a composite organic protective film.

Figure 2 is a flow chart of the preparation process of the steel surface coated with a composite organic protective film.

Detailed ways

Below with reference to the structural representation of the steel surface covered with a composite organic protective film shown in Figure 1 and the preparation process flow chart of the steel surface shown in Figure 2 covered with a composite organic protective film, further describe in detail several embodiments for realizing the method .

Example 1

Contrast Fig. 2, add 40 grams of 1500 order organic bentonites in 100 milliliters of water, stir well and place it for later use after 1 hour; Add 2 grams of water-based carbon black slurry (according to the color) in 100 grams of water-based epoxy resin emulsion with a solid content of 50%. requirements, can add other colors of color paste), 1 gram of trisodium phosphate, 20 grams of prepared organic bentonite liquid, 50 grams of 50% water-based polytetrafluoroethylene emulsion, stir evenly to make epoxy resin film-forming liquid for subsequent use . Adjust the concentration of the film-forming liquid according to the size of the workpiece and the heating temperature. Film-forming liquid: tap water = 1:5. Example 1 workpiece is a Φ20 nut. Heating temperature 400°C±10°C, keep warm for 20 minutes, take out the workpiece and immerse it in the film-forming solution whose concentration has been adjusted for 10 seconds, then take it out, and put the film-formed workpiece back into the Heating in a heating furnace at a heating temperature of 200°C±10°C, keeping it warm for 30 minutes, taking out the workpiece and cooling it in air or immersing it in water to obtain an organic protective film with a film thickness of about 15um (as shown in Figure 1).

The organic protective film of this embodiment is soaked in 5% hydrochloric acid solution for 3 days without peeling, and the corrosion point is less than 1/square centimeter. Soaked in 5% sodium hydroxide aqueous solution for 7 days, there is no abnormality, the friction coefficient is reduced and it does not stick to water.

Example 2

The steel workpiece is a Φ40 nut, the heating temperature is 400°C±10°C, and the temperature is kept for 20 minutes. The film-forming liquid:tap water=1:7.

Referring to Figure 2, first, heat the workpiece nut at a heating temperature of 400°C±10°C, keep it warm for 20 minutes, then take out the workpiece and immerse it in the film-forming liquid pool whose concentration has been adjusted for 10 seconds, and wait until the surface of the workpiece evaporates. , put the workpiece after the first film formation into the heating furnace for heating at a temperature of 150°C±10°C, keep it warm for 30 minutes, take out the workpiece and air-cool, and obtain an organic protective film with a film thickness of about 20um.

The organic protective film of this embodiment is soaked in 5% hydrochloric acid solution for 3 days without peeling, and the corrosion point is less than 1/square centimeter. Soaked in 5% sodium hydroxide aqueous solution for 7 days, there is no abnormality, the friction coefficient is reduced and it does not stick to water.

Example 3

The steel workpiece is a Φ40 nut, the heating temperature is 500°C±10°C, and the temperature is kept for 20 minutes. The film-forming liquid: tap water = 1:8;

Referring to Figure 2, first, heat the workpiece nut at a heating temperature of 400°C±10°C, keep it warm for 20 minutes, then take out the workpiece and immerse it in the film-forming liquid pool whose concentration has been adjusted for 10 seconds, and wait until the surface of the workpiece evaporates. , put the workpiece after the first film formation into the heating furnace 1 for heating, the heating temperature is 300°C±10°C, keep it warm for 15 minutes, take out the workpiece and cool it in air or immerse it in water, and then take it out to get a film thickness of about 20um organic protective film.

The organic protective film of this embodiment is soaked in 5% sodium chloride solution for 20 days without peeling, and the corrosion point is less than 1/square centimeter. Soaked in 5% sodium hydroxide aqueous solution for 10 days, there is no abnormality, the coefficient of friction is reduced and it does not stick to water.

Claims (6)

1. the preparation method of the composite organic protective film of a steel surface is characterized in that, comprises the steps:

1) aqueous epoxy resin emulsion, water or aqueous color paste are mixed and stir, it is standby to make aqueous epoxy resins film forming liquid;

2) in aqueous epoxy resins film forming liquid, add dispersant and antifriction, anti-corrosion, heat proof material, wherein, elect aqueous epoxy resins film forming liquid by ratio of weight and the number of copies as: dispersant=10:0.05-10:0.5;

3) carry out workpiece waste heat film forming

Iron and steel parts is heated to 150 ℃-600 ℃ in heating furnace 1; insulation makes the workpiece heat penetration; take out workpiece and immerse and contain in the aqueous epoxy resins film forming liquid pool of wt%--10wt%; stop taking-up in 5-30 seconds; in heating furnace 2, heat 60-100 ℃ of dryings, or the iron and steel parts that will make layer protecting film reheats 150 ℃-350 ℃, be incubated 20-60 minutes; cool off in cooling or the water in the taking-up workpiece air, make one deck composite organic protective film at surface of steel workpiece.

2. according to the preparation method of the composite organic protective film of the described steel surface of claim 1, it is characterized in that described dispersant is a tertiary sodium phosphate.

3. according to the preparation method of the composite organic protective film of the described steel surface of claim 1, it is characterized in that described antifriction, anti-corrosion, heat proof material are water-based polytetrafluoroethylene (PTFE) and organobentonite.

4. according to the preparation method of the composite organic protective film of the described steel surface of claim 1, it is characterized in that described polytetrafluoroethylene (PTFE) addition is controlled at aqueous epoxy resins film forming liquid by ratio of weight and the number of copies: water-based polytetrafluoroethylene (PTFE)=10:1-10:5; The organobentonite addition is controlled at aqueous epoxy resins film forming liquid by ratio of weight and the number of copies: organobentonite powder=10:0.1-10:2.

5. according to the preparation method of the composite organic protective film of the described steel surface of claim 1; it is characterized in that; described aqueous color paste is the inorganic matter colouring agent, and the inorganic material powders granularity is in 1000-2000 order scope, and its inorganic matter colouring agent is carbon black, iron oxide black or titanium dioxide.

6. according to the preparation method of the composite organic protective film of the described steel surface of claim 5; it is characterized in that; described inorganic matter colouring agent addition is controlled at aqueous epoxy resins film forming liquid by ratio of weight and the number of copies: inorganic matter colouring agent=10:0.2-10:0.3, inorganic matter colouring agent evenly distribute in aqueous epoxy resins film forming liquid.

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