KR20060088285A - Cr-free anti-fingerprinting resin component and steel sheet coated therewith having excellent formability and a high corrosion resistance, with high lubricating property and conductivity - Google Patents

Abstract

The present invention is characterized in that the chromium-free characterized by the surface electrical conductivity and high corrosion resistance while ensuring the processability obtained by performing the conventional three-coating treatment with only one micrometer polymer coating, omitting chromate treatment and phosphate coating on the surface of the galvanized steel sheet ( The present invention relates to a method of manufacturing Cr-free anti-fingerprint steel sheet, and its purpose is to provide surface lubricity for improving environmentally friendly conductive one-component chromium-free anti-fingerprint steel plate due to its poor workability in deep processing parts. The present invention provides a method for producing a one-component home appliance chromium-free fingerprint steel plate having excellent workability and high corrosion resistance and conductive properties.

Description

Cr-free anti-fingerprinting resin component and steel sheet coated therewith having excellent formability and a high corrosion resistance, with high lubricating property and conductivity}

Figure 1. Schematic explanatory drawing about the layer structure of this invention anti-fingerprint steel plate structure

Figure 2 (a) is a conventional one-component chromium-free fingerprint steel plate, Figure 2 (b) is a state after drawing the one-component chromium-free fingerprint steel plate of the present invention, respectively, as a comparative explanatory view of the processability improvement effect of the present invention. It is shown.

The present invention is conventionally chromate treatment, phosphate treatment, polymer resin treatment by coating on the surface of the plated steel plate using the anti-fingerprint resin coating composition using chromium-free resin and the solution composition without performing chromate treatment and phosphate treatment on the galvanized steel sheet. It relates to a method for producing a one-component chromium-free fingerprint steel plate having a workability equal to or higher than that of a product made by performing the step.

In the case of conventional anti-fingerprint steel plate, chromate treatment is used to improve adhesion between zinc plated layer and resin and complement corrosion resistance. Phosphate treatment is performed to secure surface appearance, adhesion and processability.

However, in recent years, the use of chromium has been banned in accordance with international heavy metal regulations, and the use of chromate has been banned. In addition, as electrical products change from analog to digital in the home appliance field, the electrical conductivity of steel sheets is newly required. In particular, various problems such as noise or paper jams when using existing internal fingerprint steel sheets in home appliances such as copiers, computers, and DVDs have been identified as defects of our products, and many design changes and efforts have been made to reduce them. As the cause is revealed as a problem caused by the consumer electronics customers have been asked for additional conductivity in addition to the existing physical properties of the steel sheet.

In anti-fingerprint steel sheet, phosphate is an oxide of phosphoric acid and zinc, and is usually coated about 2 g / m ² , thereby acting as a non-conductor, thereby degrading the conductivity of the steel sheet. In addition, since the anti-fingerprint resin has insulator properties, the coating amount is limited in order to impart conductivity. Therefore, in order to secure the conductivity of the anti-fingerprint steel sheet, the phosphate treatment cannot be performed and the application amount of the anti-fingerprint resin is also limited.

Therefore, in order to develop environmentally friendly chromium-free fingerprint steel sheet, it is possible to secure fingerprint resistance, chemical resistance, processability, corrosion resistance, etc. by applying an appropriate amount of anti-fingerprint resin directly on the galvanized steel sheet without chromate treatment and phosphate treatment. It is very important. At this time, in order to coat all the properties of the fingerprint on the galvanized layer to make all the above properties the same as the existing fingerprint-proof properties of the fingerprint is very important.

As disclosed in Korean Patent Application No. 03-90467, a one-component chromium-free fingerprint paper has been developed, but blackening occurs in deep processing, and complaints have been raised. In addition, during the press process, frictional heat is generated between the resin surface and the mold in the deep processing part, and the mold temperature is increased. Therefore, the temperature of the steel plate surface is increased to 100 ^o C or more, so that the resin is detached between the processing die and the mold, resulting in small fragments in the mold. The problem of adsorption and fixation has not been solved. In the subsequent process, the resin fragments are transferred to the steel sheet, causing surface defects on the steel sheet, thereby reducing productivity and appearance quality.

Therefore, in the present invention, in order to give the resin additionally contributes to the processability of the phosphate, the glass transition temperature is high even if the temperature of the resin is changed to a thermosetting resin rather than thermoplastic and the surface temperature of the steel sheet is increased above 100 ^o C. It was noted that the denaturation of the resin should not be caused.

Accordingly, in the present invention, by adding a suitable amount of wax to ensure processability based on the epoxy resin having a high glass transition temperature, and coating the resin composition containing various additives such as lubricant for rapid crosslink formation and processability improvement by coating the galvanized steel sheet The aim was to enable the development of this excellent high lubrication conductive chromium free fingerprint.

In order to achieve the above object, the present inventors give lubricity by adding wax to the chromium-free fingerprint resin developed in advance to improve processability, which is a fundamental problem of the previously developed one-component chromium-free fingerprint product. In addition to improving the process blackening and surface lubrication, it was also considered to meet the conditions to prevent corrosion and conductivity and chemical resistance properties from being reduced.

In the present invention thus obtained, in order to obtain a chromium-free anti-fingerprint resin composition for an electro-galvanized steel sheet of 1 coating 1 baking type, an epoxy resin is used as a binder and 10 to 30 parts by weight of the amine resin based on the weight of the resin solid content. At least one silica selected from colloidal silica or fumed silica and at least one silane selected from glycidoxy propyl ethoxysilane, aminopropyl ethoxysilane and methoxyoxypropyl drimethoxysilane. 1 to 10 parts by weight of 10 to 50 parts by weight of 0.8 parts, zirconia sol, alumina sol, and titanium sol are added and mixed, followed by polyethylene wax, synthetic paraffin, microwax, and polyfluoroethylene It is prepared by adding 0.5 to 10% by weight of one, two or more of resins, fatty acid amide compounds, and fluororesin lubricants and then using pure water. The anti-fingerprint coating solution composition and the fingerprint resin solution composition, which are obtained by diluting the final solid content of the anti-fingerprint solution to 15 to 25% by weight, are coated in a 1-coating 1 bake type using a roll on an electrogalvanized steel sheet. It consists of a method of producing high corrosion-resistant chromium-free fingerprint steel plate with excellent chemical resistance and conductivity, characterized in that the baking and cooling at a coated steel sheet temperature of 160 ~ 220 ^° C so that the adhesion amount 0.8 ~ 1.3 g / m ² .

The optimum amount of resin to satisfy both electrical conductivity and high corrosion resistance was 0.8 ~ 1.3 g / m ² . In the case of processability, there is a tendency to be relatively good as the amount of resin attached increases more than 0.8 g / m ² , but the conductivity decreases as the amount of adhesion increases, the conductivity can not be secured if it exceeds 1.3g / m ² . Therefore, the present inventors have excellent surface lubricity within the adhesion amount range that satisfies corrosion resistance, conductivity, and chemical resistance, thereby improving processing blackening and resin peeling of deep-processed parts, and securing existing characteristics and surface resistance values of 0.1 mOhm or less. The focus was on the production of chromium-free anti-finger steel sheet to ensure excellent conductivity and high corrosion resistance of less than 5% of white rust generated 120 hours of salt spray test.

The present invention is a method for producing a chromium-free fingerprint steel sheet excellent in the high corrosion resistance, conductivity, chemical resistance, and external workability of the steel sheet as a solution of water-soluble chromium-free type that is harmless to the human body and environmentally friendly as described above. It is the point. In order to exhibit the various properties described above, polyethylene wax and fluorine wax are added to various polymers of organic or organic type, and as shown in Table 1, the properties vary depending on the main resin type and the wax composite.

Adding wax to the acrylic resin improves surface lubricity and improves workability, but there is a problem in that the corrosion resistance is relatively lowered. In the case of the acrylic / urethane composite system, the corrosion resistance can be improved, but the alkali property is inferior. As a result of experiments with various types of resins and conditions of additives several times, epoxy type shows more stable properties of corrosion resistance and alkali property than acrylic or urethane resin when wax is added.

In the case of epoxy resins, 50 parts by weight to 90% by weight of the coating film is suitable, and the amount of resin used in combination is preferably not more than 10 parts by weight to 30 parts by weight. That is, in order to obtain the chromium-free fingerprint resin composition for an electro-galvanized steel sheet of 1 coating and 1 baking type, an epoxy resin is used as a binder, and the amine resin is 10 to 30 parts by weight based on the weight of the resin. desirable. When it is less than 10% by weight, the adhesive strength due to crosslinking is insufficient, and when it exceeds 30% by weight, workability is deteriorated. In the production of epoxy resin, it is designed to have many OH groups to crosslink at high temperature, and they are crosslinked at high temperature to thermoset and denature the resin to an appropriate temperature to obtain newly required physical properties.

There is a water solubility and crosslinking through OH structure, but in the production of epoxy-based compounds and amine-based compounds of epoxy resin, the use ratio is usually 0.5 to 2.0, preferably 1 to 1.8, in an equivalent ratio (epoxy / amine). The concentration in the organic solvent of the epoxy compound may be set by the solvent and the epoxy compound type and the concentration of the amine compound to be reacted, but is usually 5 to 100% by weight in terms of solid content, but preferably 30 to 80% by weight. It is enough. If the concentration is higher than 80% by weight, irreversible curing reaction may occur and water-soluble resin may not be obtained. If the concentration is lower than 30% by weight, the production efficiency is lowered, respectively, which is not preferable.

The organic solvent for dissolving the amine compound may be selected from compounds capable of dissolving amine compounds other than ketone organic solvents, aldehyde organic solvents, ester organic solvents and halogen organic solvents, preferably methanol, Alcohols, such as ethanol, and tetrahydrofuran are used. Examples of the curing agent include diethylenetriamine, triethylenetetramine, isophoronediamine, diaminodiphenyl methane, diaminophenylsulonephone, polyamide, dicyandiamide, hexahydrophthalic anhydride, methyltetrahydroanhydride anhydride and methyl anhydride. Direct acid, novolak-type phenolic resin, tertiary amines, imidazoles, amine complexes of boron trifluoride, melamine, metyrolmelamine, resol type compounds and the like are used. As the curing accelerator, tertiary amines such as tri-n-butylamine, benzylmethylamine, 2,4,6-tris (dimethylaminomethyl) phenol, 2-methylimidazole, 2-ethylimidazole, And imidazoles such as 2-ethyl-4-methylimidazole and 2-phenylimidazole.

Although it hardens enough according to the addition of a hardening | curing agent to the organic resin as mentioned above, in order to obtain a more firm film | membrane, a hardening accelerator is used. The epoxy resin aqueous solution is obtained by reacting or polymerizing an epoxy compound and an amine compound by mixing an epoxy compound or an organic solvent solution with an amine compound, an aqueous solution, an organic solvent solution, or a mixed solution of water and an organic solvent. It can obtain by adding water to the mixed solution of water and an organic solvent, or an epoxy resin solution, heating, and distilling off an organic solvent and an unreacted amine compound.

In case of epoxy resin, it forms dense barrier film by reaction between epoxy resin and crosslinking agent, and it is strong against corrosion factors such as salt and oxygen, and it has excellent corrosion resistance and chemical resistance because hydroxyl group in molecule has excellent adhesion with base material. . In order to improve the corrosion resistance and electrical conductivity of the epoxy resin solution, colloidal silica, silane coupling agent and curing agent are added to the resin solution. The particle size of silica should be less than 10 nanometers to improve the density of the resin film, and by adding silica in a certain order to the epoxy resin solution, storage stability, adhesion and corrosion resistance are improved. Colloidal silica or fumed silica is used as silica, and the addition amount is preferably 10 to 50 parts by weight based on 100% by weight of the resin solids. If it is less than 10 parts by weight, the conductivity is deteriorated, and if it exceeds 50 parts by weight, the workability is deteriorated. In addition, in order to further improve adhesion and corrosion resistance, one or more of zirconia sol, alumina sol, and titanium sol is selected in a total of 1 to 10 parts by weight. The reason for selecting 1 to 10 parts by weight here is to facilitate the film formation, and because of the effects of conductivity and workability as described above.

In order to fix the epoxy resin and silica to improve processability and corrosion resistance, a silane coupling agent mixed with the silica may be used. In this case, glycidoxy propyl ethoxysilane, aminopropyl ethoxysilane, and methoxyoxypropyltrimethock The reason for selecting one or two of the silanes and mixing them with the silica (silica: silane) in a range of 1: 0.2 to 0.8 is that the crosslinkability is not improved when the ratio is less than 1: 0.2, and when the ratio exceeds 1: 0.8, workability is poor. Because there is a risk of falling out. The mixed silica mixture is added in an amount of 10 to 50 parts by weight based on 100% by weight of the resin solid content, thereby lowering the baking temperature and forming an excellent crosslinkable film. In addition, the epoxy resin solution composition prepared by adding 0.5 to 10% by weight of polyethylene wax, synthetic paraffin, microwax, polyfluoroethylene resin, fatty acid amide compound, and fluororesin lubricant for the improvement of processability, It can be applied to a galvanized steel sheet to produce a chrome-free fingerprint steel sheet. When the amount of the lubricant added is less than 0.5% by weight, corrosion resistance and weather resistance are not guaranteed, and the effect is not effective on workability, and when it exceeds 10% by weight, chemical resistance is deteriorated.

The coating solution is generally coated by a roll coating method to apply a resin solution so that the dry film thickness of the steel sheet is 0.8 to 1.3 g / m ^2, followed by baking at a steel plate temperature of 160 to 220 ^° C., followed by air cooling or water cooling, followed by drying. To prepare a steel sheet. As a device for heat treatment, a hot stove, dry heating, high frequency induction furnace, infrared furnace, etc. may be used, and the treatment is preferably performed at 160 to 220 ^° C. When baking the resin solution composition was applied to the steel sheet to below 160 ^o C is not supported, the curing reaction of the resin is performed correctly, it is difficult to expect the effect of the corrosion resistance and other physical properties of the coating film corresponding to the under-section is in excess of 220 ^o C This is likely to cause cracking or yellowing of the film.

Generally, when the steel sheet is heated to dry the resin film to form a dry coating film, air cooling or water cooling is performed, and the cooling method itself employs a conventional method.

Hereinafter, the present invention will be described in detail with reference to Examples.

(Example)

In the present invention, the coating weight of 20 g / m ² produced by the home appliance is adjusted to a solid content of 15 to 25% by weight using an anti-fingerprint resin solution of the composition shown in Table 1 and then coated and baked Drying and water cooling were performed to evaluate their properties.

Machinability

In the case of workability, a cup drawing was carried out at 15 mm at a puncher speed of 172 mm / min to a blank force of 5 tons by using a molding simulator, and the process blackness and resin peelability of the appearance were evaluated as follows.

◎: very good

○: excellent

△: incomplete

Ⅹ: low

Corrosion resistance

Corrosion resistance was evaluated by using the salt spray test equipment based on the percentage of white rust generated in 120 hours of continuous time according to ASTM B117 standard.

◎: 0-2%

○: less than 5%

△: 5-20% or less

Ⅹ: 20%

Chemical resistance

In the case of chemical resistance, three items, namely cold resistance, strong alkali resistance and corrosion resistance, were divided into acidic alkali and volatile solvents as part of durability, and three physical properties were evaluated as follows.

◎: When both are ○ or more

○: ○ If there are two or more and no △

△: when there are two or more △ and no X

       Ⅹ: when there is more than one X

The evaluation of the detailed items is as follows.

First, in the case of cold resistance, artificial sweat of pH 4.5 was prepared and 0.05ml was taken on the surface, and then maintained for 48 hours at high temperature and high humidity.

◎: No trace

○: No corrosion and fine trace

△: discoloration but no corrosion

Ⅹ: white rust and corrosion products

In the case of strong alkaline, alkaline degreasing agent for pH 12 and higher was evaluated as follows according to the degree of surface rust after 48 hours of saline spraying after washing for 2 minutes at 60 ^° C degreasing solution at a concentration of 2 ~ 3%.

◎: less than 5% of white blue

○: 5-10% of white blue

△: more than 10% of white blue

Ⅹ: Red blue

Solvent resistance was evaluated as follows according to the degree of surface rust after 48 hours of salt spraying after 10 times of surface rubbing using methyl ethyl ketone in volatile solvents. Was evaluated as follows.

◎: less than 5% of white blue

○: 5-10% of white blue

△: more than 10% of white blue

Ⅹ: Red blue

According to Table 1, the range to be presented in the present invention was able to obtain a good result as in the invention examples 1 to 11 and the other ranges when the lubricant is too low as in the comparative examples 1 to 3 as shown in the comparative example Showed no effect on processability. When the lubricant was exceeded as in the case of Comparative Examples 4 to 6, it was investigated that the chemical resistance was particularly deteriorated. In addition, even in the case of too much lubricant as in Comparative Example 6 it can be seen that the film formation is irregular and the overall physical properties are inferior.

According to the method of the present invention as described above, as shown in the drawing (1), the molded article requiring high processability is conventionally used to improve processing blackening by using a phosphate base, but in the case of a one-component type, the demand is increased in the press process. Although blackening phenomenon occurs, when processing the resin solution according to the present invention by providing a surface lubricity can improve the process blackening portion.

In the case of the drawing (2), it was observed that the flange part which is severely affected by the processing friction and the mold by cup drawing showed that the degree of blackening and resin peeling was superior to that of the chromium-free anti-fingerprint steel plate without the wax. have. In addition, it is possible to apply the core processing portion as a high-lubrication chromium-free fingerprint steel plate of high quality, excellent workability without problems during degreasing and cleaning after processing while ensuring the corrosion resistance and chemical resistance at the same level.

Claims (2)

1 Coating 1 In order to obtain a chromium-free fingerprint resin composition for an electrogalvanized steel sheet of baking type, 10 to 30 parts by weight of an amine resin based on the weight of the resin solids and a colloidal silica or 10 to 50 parts by weight of one kind of silica selected from fumed silica, or at least one silane selected from among these silicas and clycidoxy propyl ethoxysilane, aminopropyl ethoxysilane, and methoxyoxypropyldrimethoxysilane : 10 to 50 parts by weight of a silica mixture mixed at a ratio of 0.2 to 0.8, at least one selected from zirconia sol, alumina sol, and titanium sol is mixed by 1 to 10 parts by weight, respectively, and then polyethylene wax, synthetic paraffin, Prepared by adding 0.5 to 10% by weight of one or two or more of microwax, polyfluoroethylene resin, fatty acid amide compound and fluororesin lubricant To munsuji coating solution composition using a number of to, it characterized in that the final solids content of the obtained munsuji solution is diluted to 15 to 25% by weight. Using the anti-fingerprint resin composition, the baking and drying at a coated steel sheet temperature of 160 to 220 ^o C so as to have an adhesion amount of 0.8 to 1.3 g / m ² as a coating 1 bake type using a roll on an electrogalvanized steel sheet. A high corrosion resistance chromium-free fingerprint steel plate manufacturing method excellent in chemical resistance and conductivity.

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