KR100428839B1 - Manufacturing method for anti-finger steel plate - Google Patents

Abstract

The present invention is used to produce a steel plate by performing a baking process and cooling after forming a resin film by a roll coating method after the reaction chromate treatment to improve the corrosion resistance and fingerprint resistance of the galvanized steel sheet Regarding the manufacturing method of anti-fingerprint steel sheet,

After the reactive chromate treatment on the galvanized steel sheet, 25 to 40 % by weight of silica alone is added to a resin solution in which 3 to 5% by weight of ether-epoxy resin is added as a curing agent to the ethylene-acrylic resin content. Resin prepared by mixing and adding 10 to 20 wt% silica and 1 to 3 wt% titanium dioxide metal powder or by mixing and adding 10 to 20 wt% silica and 20 to 40 wt% acryl-urethane resin solution The solution is applied and baked in a temperature range of 70 to 180 ° C. to improve tacky resistance.

Description

Manufacturing method for anti-finger steel plate

The present invention is used to produce a steel plate by performing a baking process and cooling after forming a resin film by a roll coating method after the reaction chromate treatment to improve the corrosion resistance and fingerprint resistance of the galvanized steel sheet It relates to a method for producing a fingerprint steel sheet.

Anti-finger steel plate has been developed to prevent contamination due to the operator's finger prints when it enters the customer's process and to supplement corrosion resistance, but it is widely used as a part and case of home appliances. Therefore, the surface appearance of the steel sheet is a quality item that must be managed more importantly than anything else.

In general, the process of forming the resin film for the fingerprint treatment proceeds as follows using the equipment as shown in FIG. First, a reactive chromate treatment is performed on the surface of the galvanized steel sheet, and then a resin coating is formed using a coating roll facility. The resin film is formed by applying the resin solution transferred from the drip pan 1 to the applicator roll 3 through the pick-up roll as the steel sheet 5 proceeds. I'm using the way.

However, the steel sheet 5 is baked after the resin solution is applied, and then the surface is hardly cooled, that is, fine dust or surface irregularities in the process of being transferred from the tacky state to the various transfer rolls as the next process. Scratches are generated on the surface due to the like, and these scratches have a significant adverse effect on the appearance of the product surface. In order to prevent this phenomenon, it is important to keep various rolls and the like clean, but it is very difficult to always keep the rubbing equipment working for about 4-5 days a month.

That is, in the current method of manufacturing the anti-fingerprint steel sheet, due to the problems of the equipment itself, there is no suitable method to prevent the softened resin on the surface of the steel sheet from being scarred by fine irregularities on various rolls. In view of the current resin solution composition and the anti-fingerprint steel sheet manufacturing process, it is difficult to improve the tackiness of the resin film.

The present invention has been invented to solve the problems of the prior art as described above, the resin layer is coated on the surface of the steel sheet to prevent the occurrence of scratches on the surface of the steel sheet generated in the tacky state according to the resin solution coating of the galvanized steel sheet It is an object of the present invention to provide a method for producing an anti-fingerprint steel sheet to improve the product surface appearance by increasing the hardness of the product.

1 is a schematic diagram of a facility for coating a resin on a steel sheet using a coating roll,

2 is a graph showing the occurrence of tacky mark according to baking temperature.

<Description of Symbols for Major Parts of Drawings>

1: drip pan 2: pickup roll

3: applicator roll 4: backup roll

5: steel sheet

In order to achieve the above object, the method for manufacturing a to-fin steel sheet according to the present invention is a method for producing a to-fin steel sheet, which is subjected to reactive chromate treatment on an electrogalvanized steel sheet, and then 3 to 5% by weight of ethylene-acrylic resin content. To the resin solution in which% ether-epoxy resin is added as a curing agent, 25 to 40 wt% of silica is added alone, or 10 to 20 wt% of silica and 1 to 3 wt% of titanium dioxide metal powder are mixed or added. , 10 to 20% by weight of the silica and 20 to 40% by weight of the acrylic-urethane resin solution is applied to the resin solution prepared by mixing, baking at 70 ~ 180 ℃ temperature range to improve the tacky resistance do.

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

In order to improve the tacky resistance of the steel sheet, it is necessary to first add an inorganic additive to increase the hardness of the resin coating, and silica, metal salt, etc. may be representatively added as the inorganic additive. This is important above all. Second, there is a method to increase the hardness of the entire resin by physically mixing the resin with high hardness in order to make the resin component harder in the resin solution composition. Finally, after applying the resin solution and baking There is a method of quenching a softened resin film by receiving heat, and the present invention proposes a method of manufacturing a steel plate in consideration of such methods.

In a series of manufacturing processes for roll coating, baking, and cooling a resin on the surface of a steel sheet, a method of increasing the hardness of the resin surface will first be described in terms of resin solution composition. After chromate treatment on the galvanized steel sheet, a resin solution prepared by using an ether-modified epoxy resin as a curing agent in a main resin solution containing ethylene-acrylic resin and silica or metal powder as an additive. Is applied to the steel sheet.

In order to improve the corrosion resistance and tacky resistance of the resin solution in which the ether-modified epoxy resin, which is a curing agent, is added in an amount of 3 to 5% by weight based on the content of the main resin solution in the ethylene-acrylic resin (hereinafter referred to as "main resin solution"). 25 to 40% by weight to prepare a resin solution. At this time, when the content of the added silica is less than 25% by weight, the tacky resistance of the resin film is not secured, and when the content of the silica is more than 40% by weight, the adhesion to the base steel sheet is lowered.

In addition to silica, the metal powder also improves the tacky resistance. In this case, the metal powder to be added should have a particle diameter of 0.5 micrometer or less . If the particle diameter of the metal powder is larger than 0.5 micrometer, the particle diameter of the metal powder is larger than that of the resin film, so that the metal particles embedded in the resin film are larger than the resin thickness and are exposed to the outside. It is not desirable because it is imported. The metal powder as described above may be a special metal powder coated with titanium dioxide on the surface of the mica (Mica) having a plate-like structure. In addition, the addition amount of the metal powder which can improve the tacky resistance of the resin film as described above is preferably added in the range of 1 to 3% by weight when the silica is added in the range of 10 to 20% by weight. If the content of the metal powder is less than 1% by weight can not be expected to improve the tacky resistance. On the contrary, when the content is more than 3% by weight, the viscosity of the solution is increased, so that a surface defect such as resin streaks occurs after the coating. In addition, in the case of the metal powder, not only the tacky resistance is improved, but also the remaining property in the resin film improves the conductivity, and thus the conductive amount is sufficient for the above-mentioned dosage, and the granulation of the metal powder also plays an important role. Do it. It is best for the metal powder granular form to have a plate-like structure, and the plate-like structure has a property of facilitating the flow of current by having an overlapping form in the resin film. On the contrary, when the granules are spherical, the overlapping between particles at the same content is smaller than that of the plate, and the granular form is limited to the plate because the sludge is more likely to settle in the solution than the plate structure.

Next, the influence on the tacky resistance according to the change of the resin type in the resin solution will be described. The resins have their own inherent properties, but when the film is formed, the film hardness may be high or low, but the resin having favorable tacky resistance is preferably the resin having the higher film hardness at the ambient temperature at that time. That is, the resin having a high glass transition temperature corresponds to this.

It is possible to improve the tacky resistance of the entire resin to some extent by physically adding a resin having a high hardness of the coating to the main resin solution used in the present invention and changing the ratio thereof. Resin that can improve the hardness of the coating is typical of the acrylic-urethane, epoxy-based, phenoxy-based resin, the acrylic modified urethane-based resin modified with acrylic is preferable among the urethane-based resin, more preferably the acrylic resin modified urethane resin Among them, methyl methacrylate resin is more advantageous than ethyl and butyl acrylate resin because methyl methacrylate resin has high glass transition temperature. However, epoxy resins and phenoxy resins have a high glass transition temperature, but since the solution state is synthesized in an emulsified form, there is a disadvantage of lowering the glossiness of the resin film even when a small amount is added.

At this time, the content of the acrylic modified urethane resin added with 10 to 20% by weight of silica is suitable for 20 to 40% by weight. If it is less than 20 wt%, there is no tacky resistance effect, and if it is more than 40 wt%, the chemical resistance and corrosion resistance of the resin solution, ethylene-acrylic resin and ether-modified epoxy resin film, are deteriorated.

And the content of the molecular weight of the ether-modified epoxy resin used as a curing agent of the main resin solution is suitable 3 to 5phr. The reason is that if the content is smaller than 3 phr, the curing reaction is not sufficiently made, so it is difficult to secure chemical resistance. If the content is more than 5 phr, the unreacted epoxy resin overinjected more than necessary inhibits the physical properties of the film.

Next, a description will be given of a tacky prevention method according to the cooling method after the anti-fingerprint resin coating and baking treatment corresponding to the end of the anti-fingerprint steel sheet manufacturing process. Conventional resin coating after baking temperature is preferred a temperature range of 70~180 ℃, when the baking temperature is less than 70 ℃ and the mothayeo of the curing reaction of the resin is insufficient coating properties decrease, whereas if larger than 180 ℃ resin column of Since the deformation is accelerated, the physical properties of the steel plate are changed. Therefore, when manufacturing the anti-finger steel sheet, the resin selects a resin which is baked in the above temperature range. Usually, a low-temperature baking resin aimed at a baking temperature of 70 to 80 ° C. and a high temperature baking resin aimed at 110 to 120 ° C. Can be divided into In general, high temperature baking is generally performed by coating and baking after cooling because there is no space and time for cooling after baking, but low temperature baking is usually performed by coating and baking after cooling. However, as shown in FIG. 2, in the case of air-cooling treatment time of 15 seconds or less in the low temperature calcined resin, the occurrence of tacky according to the baking temperature is caused by the softening of the resin layer due to the lack of cooling after the baking when the baking temperature is 70 ° C. or more. It can be seen that, to prevent this, the baking temperature should be reduced to a level below 65 ℃, which has the disadvantage of deteriorating the film properties. Therefore, when the air cooling treatment time is 15 seconds or less when the low temperature calcined resin is applied, the tacky phenomenon can be prevented by improving the hardness of the resin layer by water cooling.

In addition, since the physical properties greatly depend on the thickness of the coating film during the production of the resin steel sheet, the drying thickness of the resin film to be applied is preferably 0.5 to 1.5 micrometers (µm). This is because when the film thickness is smaller than 0.5 占 퐉, the film thickness is thin, making it difficult to secure sufficient chemical resistance and the like, and when the film thickness is larger than 1.5 占 퐉, the weldability deteriorates with the increase in the film thickness.

Hereinafter, the present invention will be described in more detail with reference to specific invention examples and comparative examples.

A main resin solution prepared by adding 15% by weight of colloidal silica having a particle size of 20 nanometers (nm) to an ethylene-acrylic copolymer resin having a solid content of 15% was dispersed therein, and an epoxy resin having a molecular weight of 900 was dispersed in water. 5 wt% is added to prepare a resin solution.

After coating the cold-rolled steel sheet with zinc plating amount of 20 g / m 2, chromate treatment of 50 g / m 2, applying the resin solution prepared in the above composition by the roll coating method, and then heating the steel sheet at 80 ° C. Next, by air-cooling to produce a steel sheet having a dry resin film thickness of 1 micrometer (µm).

At this time, to measure tacky phenomenon, the cotton colored with black ink (wet the cotton with ink and dried and used, soaked with ink is to improve the marking of the steel sheet and cotton when the cotton on the steel sheet), After pressing and squeezing on the steel sheet cooled for 5 seconds, the area of cotton soaked on the steel sheet was divided into five stages, and the evaluation criteria were as follows.

◎: No cotton on the steel plate.

(Circle): Area of the cotton which stuck to the steel plate: 0-20%

□: Area of cotton on steel sheet: 20-50%

(Triangle | delta): Area of the cotton stuck to the steel plate: 50 to 80%

× area of cotton on steel sheet: 100%

In chemical resistance evaluation, the degree of peeling and discoloration of the resin coating film was evaluated by dividing the film in 10 round trips with MEK in 5 stages.

◎: No peeling of resin coating film, color difference (difference in whiteness before and after treatment) ΔΕ1 or less

(Circle): Color difference (whiteness difference before and after a process) without peeling of resin coating film (DELTA)

□: No peeling of resin coating film and color difference (difference in whiteness before and after treatment) ΔΕ5 or more

(Triangle | delta): Partial peeling of resin coating film (The peeling part is 30% or less of resin conductive cloth surface.)

X: partial peeling of resin coating film (more than 50% of resin conductive cloth surface)

Conductivity evaluation was replaced by weldability evaluation. The detailed evaluation method is as follows. The welding machine was a pneumatic welding machine (Daihen RPA-33A), which was evaluated at a welding pressure of 7.8kA with a press force of 250kgf and a welding time of 15 cycles, and then measured by tensile strength after welding with two specimens attached.

Table 1 shows the results of evaluating tackiness, chemical resistance, weldability, and the like according to the resin type, various additives, and cooling method differences for improving tackyness in the ethylene-acryl copolymer.

division Resin solution (% by weight) Additive (% by weight) Cooling method (water / air cooling) Quality evaluation chief ingredient Hardener Suzy Silica Metal powder Tacky Prevention Chemical resistance Weldability (kg / spot) Ethylene-Acrylic Resin Ether-epoxy resins Acrylic Urethane Resin Colloidal Titanium Dioxide (TiO ₂ ) Processing time (seconds) Comparative Example 1 100 One - 15 - Air-cooled 5 - △ - Comparative Example 2 〃 10 - 15 - 〃 - ◎ - Comparative Example 3 100 3 10 15 - 〃 △ ◎ - Inventive Example 1 〃 〃 20 15 - 〃 ○ ○ - Inventive Example 2 〃 〃 40 15 - 〃 ◎ ○ - Comparative Example 4 〃 〃 50 15 - 〃 ◎ △ - Comparative Example 5 100 3 - 20 - 〃 △ ◎ - Inventive Example 3 〃 〃 - 25 - 〃 ○ ◎ - Inventive Example 4 〃 〃 - 40 - 〃 ◎ ◎ - Comparative Example 6 〃 〃 - 50 - 〃 ◎ □ - Inventive Example 5 100 3 - 15 One 〃 ○ ◎ 238 Inventive Example 6 〃 〃 - 15 3 〃 ◎ ◎ 245 Comparative Example 7 〃 〃 - 15 5 〃 ◎ ◎ 260 Comparative Example 8 100 3 - 15 - Air-cooled 5 × ◎ - Comparative Example 9 〃 〃 - 15 - Air-cooled 10 △ ◎ - Inventive Example 7 〃 〃 - 15 - Air-cooled 15 ○ ◎ - Inventive Example 8 〃 〃 - 15 - Water cooling ◎ ◎ -

As described in detail above, using the method of manufacturing a to-final steel sheet of the present invention, there is a remarkable effect of preventing the occurrence of surface defects of the steel sheet due to the tacky state of the resin film to improve the appearance quality of the to-steel plate.

Claims (1)

In the manufacturing method of the anti-finger steel sheet, After the reactive chromate treatment on the galvanized steel sheet, To the resin solution in which 3 to 5% by weight of ether-epoxy resin as a curing agent is added to the ethylene-acrylic resin content, 25 to 40 % by weight of silica is added alone, or 10 to 20% by weight of silica and 1 to 3% by weight. A resin solution prepared by mixing and adding% titanium dioxide metal powder or by mixing and adding 10-20% by weight of silica and 20-40% by weight of acryl-urethane resin solution, A method of manufacturing a to steel plate, characterized in that to improve the tack resistance by baking in the temperature range of 70 ~ 180 ℃.