KR20010084852A - Method for Anti-rusting of metals - Google Patents

Abstract

PURPOSE: A method for forming a rust preventing film on metals using a far infrared ray heating apparatus is provided to prevent metal or non-iron metals such as automobile, home appliances and building materials from being corroded, thereby preventing deterioration of performance of the product articles and substantially increasing durability thereof. CONSTITUTION: The high density rust preventing film forming method comprises the processes of coating a metallic film composition on the material of metal or non-iron metal; and heating the metallic film composition coated material of metal or non-iron metal using a far infrared ray heating apparatus so as to obtain superior corrosion resistance and cohesion, wherein a heating source by the far infrared ray heating apparatus has a high absorption activity of the metallic film composition which is in the wavelength range of 0.75 to 1.000 microns, and wherein the method comprises the process of heating the film to a temperature of 260 to 400 deg.C for 15 minutes without preheating in case of a thin film having a coating thickness of the metallic film composition of 6 to 8 microns while the method comprises the process of heating the film at a preheating temperature of 60 deg.C and at a base heating temperature of 260 deg.C in case of a thick film having a coating thickness of the metallic film composition of 8 to 13 microns. The method for forming a film having temporary rust preventing power on metals comprises the process of forming a ferric oxide, iron trioxide or iron tetraoxide having a thickness of 40 to 500 micrometers on a non-coated iron base metal by the reaction of the iron base metal and a wavelength of 0.75 to 1.000 microns emitted to the non-coated iron base metal from a far infrared ray emitting body when partially coating a metallic film composition on a metallic or non-iron metallic material.

Description

Method of forming antirust coating of metals {Method for Anti-rusting of metals}

The present invention relates to a method for forming antirust coatings of metals. More specifically, the present invention relates to a novel anti-corrosion coating method using a far-infrared heating device for preventing corrosion of metals or nonferrous metals due to electrical factors.

Conventionally, as a method of rust prevention of various products based on metals and nonferrous metals, electroplating, hot-dip plating, and powder or liquid coating methods have been employed, but these methods have disadvantages in that they are vulnerable to corrosion resistance or pollutants. However, as a method for improving the corrosion resistance and at the same time solving the environmental pollution, the antirust metal coating composition is known as Japanese Patent Publication No. 60-50228 (EPO Publication 468883A1) under the trademark "DACRO-DIP". It is performed and is performed openly. This component is composed of oxohydroxy ethers such as chromic anhydride (CrO ₃ , Cr ₂ O ₃ ), dispersants, thickeners, dipropylene glycol, zinc flakes (Zn) and zinc oxide (ZnO), aluminum pans and their oxides (Al, Al ₂ O ₃ ), deionized water (H ₂ O), etc., which is applied to the coating material, and then formed into an appropriate coating film by sprinkling, draining, spraying, etc. The present invention relates to a method of forming a dry film having a thickness of 7 to 12 μm by preheating to 150 ° C. based on equipment such as a box type or a hanger type, followed by high temperature heating (300 ° C.).

The known method generates hot air using a heat source such as LPG, LNG, electric heater, and takes 10 to 20 minutes and 20 to 100 minutes, respectively, at temperatures ranging from 50 to 150 ° C. and 260 to 380 ° C. As heat treatment was performed twice for 30 to 120 minutes, there were serious problems in both sides such as economics and efficiency.

In addition, by adopting such a heating method, the object to be heated must be heated to 300 to 380 ° C by convection and conduction. Therefore, a long period of about 60 to 80 minutes is required depending on the heat capacity of the object. In addition, the appearance of the coating was damaged by the combustion gases such as N ₂ , CO, CO ₂ , SO ₄ , and C. As a result, the performance of the rust-preventing coating was deteriorated, resulting in the appearance of defective products due to uneven heating.

In addition, the above known method deteriorates the working environment due to the noise generated by the combustor installed at the top of the facility and the dust generated by the vibration and noise caused by the circulation and the vibration in order to supply hot air uniformly. Has been.

In addition, since the indirect hot air heating method is first heat-cured from the surface layer of the dark dip applied to the object to be treated, the moisture and volatile organic vapors in the lower layer are released, thereby destroying the film, thereby degrading the density and adhesion of the film. There was a closure where quality could be compromised if attention was not paid to temperature control.

As such, Japanese Patent Application Publication No. 60-50228 is proposed to prevent non-uniform coating film formation due to low density, pinhole generation, and flow of the coating liquid during preheating. However, this does not alleviate the above problems, and to solve this problem, A patent that adopts a heating method is known as Japanese Patent No. 60-10109, but there are products that are expensive and cannot be processed depending on the shape of the object to be processed. This method is applicable to small parts such as bolts, nuts, springs, washers, etc. Is not practical because it has an impossible disadvantage.

The present invention has been devised in view of the problems of the known methods described above, which is installed in a narrow space, and has a low cost of equipment, and thus, a new anti-corrosion coating film forming method without environmental pollution incorporating a far-infrared heating method capable of saving production costs. To provide that purpose.

The above object of the present invention has been achieved by providing a method of forming a high-quality antirust coating film having a beautiful appearance and high density and high corrosion resistance using the infrared wavelength band of 0.75 to 1,000 µm in consideration of the fact that the dark dip is an absorber of far infrared rays.

Hereinafter, the specific configuration and operation of the present invention will be described with reference to Examples, but the scope of the present invention is not limited only to these Examples.

1 is a schematic system of a far-infrared heating apparatus which is preferred for practicing the present invention.

Figure 2 is a diagram showing the principle of infrared absorption and radiation according to the present invention.

Figure 3a and 3b is a view showing a cross-sectional view of the dry rustproof film according to the conventional method and the method of the present invention, respectively.

Figure 4 is a diagram showing the heat drying process of the rust preventive film according to the present invention, the infrared absorption and radiation principle.

5 is a view showing the temporary rust-proof film formation of the partial coating treatment,

6 is a graph comparing the curing operation of the workpiece according to the conventional method and the method of the present invention.

In the present invention, unlike the conventional LPG and LNG heating methods, the main heating process is only 10 to 20 minutes for a short time without a preheating process, so that the components constituting the dark dip are directly absorbed the special wavelengths of far infrared rays by using the far infrared active material. It is also a method that can form an efficient dry rustproof film.

1 is a schematic system of a far-infrared heating apparatus preferred for practicing the present invention,

Figure 2 is a diagram showing the principle of infrared absorption and radiation according to the present invention.

In addition, Figure 3a is a cross-sectional view of the dry rustproof film formed by the indirect hot air heating method through the conventional LPG drying furnace, Figure 3b is a cross-sectional view of the dry rustproof film formed on the basis of the far infrared absorption and radiation principle according to the present invention.

Figure 4 is a diagram showing the heating and drying process of the rust preventive film according to the present invention, far infrared absorption and radiation principle,

5 is a temporary film of ultrathin films of Fe ₂ O ₄ and Fe ₂ O ₃ having anti-rusting properties by reaction between far-infrared rays irradiated on uncoated parts and iron as a material when partial coating is performed, such as a brake disc of an automobile. The figure shows the formation of antirust film.

In addition, Figure 6 is a graph comparing the curing action of the workpiece according to the conventional heating method and the present invention far infrared heating method.

According to the present invention has the following significant advantages.

First, the essential preheating process of the conventional LPG, LNG heating method is vitalized and eventually shortens the antirust coating treatment time (see FIGS. 1 and 2).

Second, by directly absorbing the special wavelength of far infrared rays and heat generation can form a high-density dry rustproof film in a short time (see Fig. 2).

Third, there is no need for large-scale equipment, no expensive fuel, and no blower, so there is no dust generated by vibration, and no dust is attached to the wet film. Can be formed (see FIG. 3B).

Fourth, in the conventional LPG and LNG indirect hot air heating method, the surface layer of the rust-preventive coating applied to the object to be treated is heated and cured, and the film is destroyed while releasing moisture and volatile organic vapors from the lower layer. The method of the present invention solves this problem (Figure 4).

In particular, since the thermal energy transfer of infrared rays according to the present invention is a radiation type (see FIG. 4), an anti-rust coating composition (dark dip) in which thermal energy is directly and instantaneously applied to an object to be treated, unlike a hot air circulation type that heats air, which is an intermediate heat medium. ), The heating effect is increased, so the energy saving effect can be achieved.

The absorbance of infrared rays varies depending on the type or surface roughness of the workpiece, but when the workpiece is iron (Fe), it is directly emitted from the infrared wavelength and far infrared heat source emitted when iron atoms or molecules become unstable due to temperature rise. It helps to cure the workpiece assembled up and down and left and right by the radiated heat energy (see Fig. 4).

According to the method of the present invention, secondary radiation is generated by re-reflection on the surface of iron (iron) having a large reflectance of far-infrared wavelength absorbed by the rust-preventive coating composition due to the absorption, transmission, and reflection of infrared rays, and is laminated with a heat promoting effect. It has a hardening effect on the lower workpiece, and since only the rust-preventive coating composition reaches the curing temperature by self-heating and is hardly affected by the heat capacity, a uniform dry coating can be obtained even in a short time of 10 to 15 minutes. (See FIG. 6).

On the other hand, zinc flakes (Zn) oxidized by an aqueous solution of chromic anhydride (CrO ₃ ), which is the main component of the rust-preventive coating composition according to the present invention, and ZnO, Al ₂ O ₃ , H ₂ O, and low molecular weight oxohydroxyether, which are pH adjusting agents Insoluble Cr ₂ O ₃ produced by reduction by DPG, TEG, cellulose derivatives and organics is a far-infrared activator, which generates large energy due to self-heating in the molecule due to penetration, absorption and resonance by far-infrared rays. Energy is converted into activating energy, which induces molecular motion, vibration cloud, improvement motion, stretching motion, and angular motion to promote hardening reaction of metal film composition, thereby improving hardening time compared to conventional forced blowing convection method using LPG and LNG as heat sources. There is a significant shortening effect. In addition, Fe ₂ O ₃ and Cr ₂ O ₃ produced by an interfacial reaction between an aqueous solution of chromic anhydride (CrO ₃ ) and iron (Fe) as described in [1] emit some of the absorbed electromagnetic waves back to the electromagnetic waves. Due to its characteristics, it radiates electromagnetic waves emitted to the workpieces around and above and below, and thus has a synergistic effect on thermal efficiency. Even when a large amount of workpieces are produced in a stacked form, a constant temperature balance can be maintained.

_{2Fe + 2CrO 3 -> Fe 2} O 3 · Cr 2 O 3 ‥‥ [1]

The main component of the far-infrared emitter is ceramic composed of SiO ₂ , Al ₂ O ₃ , Fe ₂ O ₃ , Cr ₂ O ₃ , and according to Kirchoff's law, the dark-dip component is also Al ₂ O according to the principle of absorber. ₃ , Fe ₂ O ₃ , Cr ₂ O ₃ contains a large amount of far infrared radiation absorbs well, heating efficiency is high. Infrared light, which is an important component of rust preventive coating composition, is a thickening agent of DPG or TEG cellulose derivative, which causes resonant motion of organic molecules due to its good absorption. It causes the eccentric movement and accelerates the curing reaction of the dip.

In addition, the infrared ray has a characteristic of actively absorbing chromic acid compounds (CrO ₃ , Cr ₂ O ₃ ), which is a dark dip component, and emits secondary radiation wavelengths to promote the reaction.

On the other hand, when far-infrared rays are absorbed in water (H ₂ O), which is a component of the dark dip, the water molecules are activated by the resonance absorption phenomenon and uniformly evaporate from the inside, so that a high-density dry film can be obtained. It is not necessary.

As described above, far-infrared ray is a metal coating composition, which is composed of chromic anhydride, water, boric acid, zinc powder, aluminum powder, dipropylene glycol, and ethyl cellulose, which are components of dark dip. It shortens the curing time and has the characteristics of producing and processing products of excellent quality in a short time.

In other words, chromic anhydride, which is a component of Dark Crop, is an infrared activating material that increases the temperature and accelerates the interfacial reaction between Cr ₂ O ₃ produced by decomposition of DPG and TEG mixed at 260 ° C and Fe. Fe ₂ O ₃ is produced as a far-infrared radiator to act as a secondary radiation action to shorten the curing time by generating and emitting electromagnetic waves.

In addition, deionized water (H ₂ O), which corresponds to 60% of the dark dip, is a material that plays an important role in film formation, and uniform evaporation is impossible in a conventional LPG oven, resulting in poor adhesion or poor pinhole. Although the long-term preheating was necessary due to the present invention, according to the far-infrared heating method of the present invention, water molecules are activated by radiation, penetrating action, and especially resonance absorption, so that water molecules migrate from the inside to the surface and evaporate, resulting in a uniform reaction reaction effect and uniformity. Due to evaporation, the adhesion amount or pinhole defect of the product does not occur as in the prior art (see FIGS. 2 to 3).

In addition, according to the method of the present invention, the cellulose derivative, DPG, and TEG are organic substances having a high absorption ability of infrared rays and infrared rays having a wavelength of 12 to 14 µm emitted from a FIR oven (see FIGS. 1 and 6). It penetrates into the material and turns into heat inside, which promotes the curing reaction with uniform temperature and thermal efficiency.

In addition, in the case of products that require partial coating, such as brake disks of automobiles, Fe ₂ O ₄ , Fe having anti-rusting properties by reacting with far-infrared rays irradiated on uncoated parts and iron as a material There is also an effect of preventing the occurrence of red rust before the formation by forming a temporary rustproof film of ultra-thin film of ₂ O ₃ (see Fig. 5). Temporary hearing ability has the advantage of controlling the thickness of the antifoam film in consideration of the atmospheric humidity of each region handling the material, the oxidation degree by sulfur dioxide (SO ₄ ). The interference color due to the thickness of the rust preventive film changes with curing time. For example, it is slightly different depending on the type of carbon steel, but when the thickness of film 40mm (0.04㎛) is heated for 1 minute, it appears colorless or light yellow, and when 70mm (0.07㎛) is heated for 3 minutes, it appears light blue, 210mm (0.21 μm) is light yellow or colorless when heated for 10 minutes, and 350 mm (0.35 μm) is light yellow or colorless to partially yellow when heated for 15 minutes.

Therefore, the thickness of the antirust coating can be arbitrarily changed in consideration of the corrosive environment and the mechanical performance of the coating material.

In addition, the conventional hot air forced circulation system using LPG and LNG as a heat source is a combustion material having a low melting point of N ₂ , CO ₂ , CO, SO ₂ , and halogen compounds (V ₂ O ₅ , Na ₂ SO ₄ ) Although there was a disadvantage in that corrosion is promoted when released into the atmosphere because it is attached to the uncoated portion, according to the method of the present invention, since the combustion gas as described above is not generated fundamentally, the instantaneous rust preventive power and the subsequent corrosion factor are removed. There is an excellent advantage.

As a preferred embodiment of the present invention, the far-infrared heating apparatus is applied with a metal film composition to a material and forms a dry film of a thin film of 6 to 8 탆, without preheating, at 260 to 400 캜, preferably at 300 캜 and of 8 to 13 탆 thick film. When the dry film is formed, the dry film is formed in a preheated atmosphere of 60 ° C. and a main heat atmosphere of 260 ° C.

Experimental Example 1 Comparison of Treatment Time between Conventional LPG Drying Furnace and Far Infrared Drying Furnace of the Present Invention

In this experiment, the treatment time of the conventional LPG heat treatment heating method and the heat treatment heating method by the far infrared drying furnace according to the present invention were compared.

The test material was randomly sampled 20 hexagonal bolts (M10 × 45L Hexa Bolts) of 10mm diameter × 50mm length by rustproof coating composition (DACRO-DIP; Japanese Patent No. 60-50228 / European Patent EPO 468-883 -A1 product).

First, the test material was ultrasonically immersed for 1 minute at 50 ° C. with Trychloro Ethylene, rinsed for 1 minute in water at 30 ° C., and then washed for 1 minute using 87 ° C. steam.

The 0.3 mm steel shot was degreased using Apron Blaster for 3 minutes and immersed for 20 seconds using the metal coating composition DACRO-DIP, followed by centrifugal dehydration with a dewatering blister 350 rpm in a dehydrator having a diameter of 550 mm.

Next, 10 pieces of material (Group A, Group B) treated with the metal film composition were subjected to conventional LPG hot air heating furnace (400,000 kW / n; total length 12 m Net Conveyor Type) (Group A) and the present invention shown in FIG. One far-infrared furnace (120 KWH; total length 8 m) was placed (group B) and heat treated according to the protocol shown in Table 1 below.

By the time of heat treatment, the economic efficiency improved by 330% when considering LNG and LPG at 100.

Heat treatment condition (protocol) Set temperature (℃) Processing time (minutes) Total (minutes) productivity(%) Preheat heating Preheat heating Group A 150 320 10 40 50 100 Group B 300 15 15 330

Salt spray test and adhesion test results after the heat treatment according to Table 1 are shown in Table 2 below.

Heat treatment result Test Items Group A Group B Salt Spray Test ¹⁾ 600 hours (no blue red) 800 hours (no blue red) Adhesion Test ²⁾ ○ ◎ 1) The salt spray test is based on KSD9501 ASTM B-117. 2) The adhesion test is based on ASTEM F1136 6.4 adnesion. 3) Test result × = defective, △ = normal, ○ = good, ◎ = very good

As a result of the salt spray test, the product produced according to the method of the present invention did not generate red blue color even after 800 hours, and the adhesion test result was extremely good.

Experimental Example 2: Change over time of the temperature of the object to be treated according to the present invention

Material SPC 75 × 150 × 1.0tm / m is completely dried after immersion of methylene chloride solution, and then heated in a far-infrared furnace equipped with 600W / h × 2 far infrared heaters for 10 minutes until the furnace temperature is 300 ℃. The temperature change of the treatment was measured over time. The temperature measuring instrument used is a non-contact thermometer and the test results are shown in Table 3 below. The distance between the test panel and the heater was 150 mm.

Measurement result of the change of the temperature of the workpiece in the far infrared heating furnace of the present invention (Unit: ℃) Group 1 ¹⁾ Group 2 ²⁾ Group 3 ³⁾ Group 4 ⁴⁾ Group 5 ⁵⁾ 5 165 170 60 180 130 10 330 385 180 450 315 1) DACRO-DIP coating 2) PB153 black (SiO ₂ , Fe ₂ O ₃ , Al ₂ O ₃ , Cr ₂ O ₃ , CrO ₃ ) treatment 3) Untreated 4) Organic rustproof coating with CMC as its main component Treatment 5) DPG and Glycol compound mixed coating treatment

As described through the detailed description and experimental examples of the present invention, the present invention has an excellent effect of providing an economical and novel anti-rust coating film formation method of environmentally friendly metals or non-ferrous metals using a far-infrared heating device. It is a very useful invention in the prevention industry.

Claims (4)

A method of forming a high-density rust preventive film having excellent corrosion resistance and adhesion by applying a metal film composition to a metal or non-ferrous metal material and heating it by a far infrared heating device. The method of claim 1, wherein the heat source by the far-infrared heating apparatus is characterized in that the wavelength band of 0.75 ~ 1.000㎛ high absorption activity of the metal film composition. The thin film having a coating thickness of 6 to 8 µm is heated for 15 minutes at 260 to 400 ° C without preheating, and in the case of 8 to 13 µm thick film, the thickness is 60 ° C. Preheating, and carried out in a heat atmosphere of 260 ° C. When the metal coating composition is partially applied to a material of metal or nonferrous metal, ferric oxide having a thickness of 40 to 500 mm based on the reaction of the iron substrate with a wavelength of 0.75 to 1.000 μm emitted from a far infrared emitter to the uncoated iron substrate, Formation method having a temporary anti-rusting power by forming iron trioxide.