KR100312121B1 - Method for manufacturing resin covered hot dipped galvanized iron using lubricating resin solution - Google Patents

Abstract

PURPOSE: A method is provided to manufacture a resin covered hot dipped galvanized iron by covering the surface of a hot dipped galvanized iron using a lubricating resin solution capable of improving stability of a lubricating resin solution, coating property with the steel sheet and formability. CONSTITUTION: The method for manufacturing a resin covered hot dipped galvanized iron using a lubricating resin solution comprises the processes of preparing a solution by putting 1 to 3 parts per hundred resin of imine-ester based resin as a curing agent and a wax solution in which polyethylene based wax having a melting point of 125 deg.C and nonpolar functional group substituted polyethylene based wax having a melting point of 62 deg.C are mixed to a mixing ratio of 1:1 into an ester-urethane resin solution; adjusting the solution by putting pure water into it so that a solid content of the solution is from 10 to 20%; putting ammonia water into the solution so that its pH is in the range of 9 to 10; preparing a lubricating resin solution by injecting 10 to 20 parts per hundred resin of the wax solution based on the base solid content into the resulting solution after injecting 10 to 15 wt.% of colloidal silica out of the solution amount into the adjusted solution; and baking the coated steel sheet at a temperature of the steel sheet ranging from 120 to 180 deg.C after coating the prepared lubricating resin solution on a coating type chromate treated hot dipped galvanized iron to a thickness of about 0.7 to 2.0 micrometers based on an adhesion amount of dried film.

Description

Manufacturing method of resin coated hot dip galvanized steel sheet using lubricant resin solution

The present invention relates to a method for producing a resin-coated hot dip galvanized steel sheet having excellent processability using a lubricating resin solution, and in particular, melting using a lubricating resin solution capable of improving the stability of the lubricating resin solution, coating property and processability with the steel sheet. To coat the surface of the galvanized steel sheet to produce a resin-coated hot dip galvanized steel sheet.

In general, hot-dip galvanized steel sheet has been developed for home appliance and construction materials for the purpose of improving corrosion resistance of steel plate by regeneration of thick film galvanized layer. Since 1991, the development of lubricated steel sheets, which can be omitted, has been carried out at five blast furnaces in Japan, and has been used for the surface coating of hot-dip galvanized steel sheets as well as electro-galvanized steel sheets.

Electro-galvanized lubricated coated steel sheet and hot-dip galvanized lubricated coated steel sheet are produced and supplied differently due to their properties such as processability and corrosion resistance.In addition to electroplating, hot-dip galvanized lubricated coated steel sheet is mainly used for indoor appliances. It is used for product vending machines.

In this way, the resin coated steel sheet is produced by subdividing according to its use and produced according to the delivery date of the customer, and thus is produced only a few days per month, and the remaining solution in the coater pan is disposed of.

This waste solution causes various problems such as environmental cost, as well as solution cost and waste solution treatment cost, so it is necessary to improve solution aging phenomenon over time.

The resin solution is mainly coated on the steel sheet through a coating method using a coater. In this case, the coating property of the steel sheet significantly affects the surface appearance and the adhesion of the coating film.

In addition, unlike electro-plated steel sheet, hot-dip galvanized steel sheet has a problem of deterioration of corrosion resistance at this part as well as surface defects of the processed part due to the damage of plating surface of the processed part due to the thick galvanized layer. The resin solution is used to improve these problems, but due to the addition of wax, the previous applicability and adhesion are reduced, and many studies for the control thereof have been conducted.

Therefore, the present invention seeks to invent a solution that can maintain solution processability, which is the original purpose of lubricated steel sheet, while improving solution stability in the lubricated steel sheet made of hot-dip galvanized steel sheet and improving the applicability and adhesion of the solution due to wax addition.

The present invention having the above object is characterized in that the surface of the hot-dip galvanized steel sheet is treated with a coated chromate solution having excellent corrosion resistance and thermally cured, and is produced by applying a resin containing clodal silica and a lubricant to the upper layer.

1 is a graph showing the relationship between the coefficient of friction according to the amount of low-melting wax in the mixing of low-melting wax and high-melting wax

In the resin solution of the present invention, the applicability to the steel sheet is mainly affected by the wettability of the solution, and when the solution is not uniformly applied to the steel sheet, it adversely affects the adhesion of the coating film along with surface defects and deterioration of corrosion resistance.

The increase in adhesion due to the increase in wettability is based on the adsorption theory. When two materials are approached very closely, they generate van der Waals forces or hydrogen bonds, which leads to an increase in adhesion strength. The degree of wetting is maximum when the surface energy of the two materials is the same or similar in polarity from a thermodynamic point of view.

In the present invention, the chromate layer forming the interface with the resin and the ester-urethane resin solution having the smallest difference in polarity were administered with about 10-15% of chlorinated silica having a large polarity. Excellent application property was ensured by adjusting the dosage of to 10-20 phr.

In addition, in order to secure processability, which is the original purpose of the lubricating resin, a mixture of two waxes of low melting point and polyethylene adjusted to high melting point was administered without increasing the amount of wax. It is possible to maintain the surface friction characteristics of the coating film.

In order to improve the solution stability, the reactivity of the resin should be reduced after mixing with the curing agent. If the reactivity is reduced, the coating strength and chemical resistance may be adversely affected. Therefore, an imine ester-based resin having appropriate reactivity with the ester-urethane resin is used as the curing agent. The dosage was 1-3 phr to control the reactivity with the resin to have excellent solution stability.

Hereinafter, the present invention will be described in more detail.

The resin solution is largely composed of a main body, a curing agent, and an additive, and the main solution is prepared by adding an additive to make the ester-urethane resin 10 to 20% solids.

If the solid content is less than 10%, it is difficult to form the coating film. On the contrary, if the solid content is higher than 20%, the surface appearance is deteriorated with the increase of the film thickness.

The curing agent used in the resin solution is prepared by using an imine ester resin in an amount of 1 to 3 phr relative to the main solid, and mixed with the main solution.

The amount of curing agent is closely related to the curing reaction rate of the resin, and the solution stability becomes poor due to the gelation and sludge generation of the solution due to the increase of incompatibility in the solution due to the curing reaction of the resin.

If the amount of the imine tester, which is a curing agent, is less than 1 phr, the curing reaction does not occur sufficiently, so that the hardness of the coating film is weakened, and thus the chemical resistance is lowered.

In addition, in order to prevent solution gelation coming from the difference between wastes, the wastes are adjusted to 9 to 10 using ammonia water.

In order to control the majesty, chlorinated silica administered for the purpose of improving corrosion resistance has a solution stability such as an increase in the viscosity of the solution or the formation of sludge, as the charges between the particles are disrupted according to the maze of the solution and the particles are entangled with each other. Because of the degradation, the majesty with the solution must be similarly adjusted.

The amount of chlorinated silica added is about 10 to 15% based on the total amount of the solution. However, in the case of a small amount, the effect of improving the corrosion resistance is small.

Since the wax added as a lubricant has little effect of improving the surface friction characteristics by adding a small amount of general polyethylene wax alone, in the present invention, the melting point substituted with a polyethylene wax having a melting point of 125 ° C. and a nonionic functional group is 62 ° C. Phosphorous polyethylene wax was mixed in a ratio of 1: 1 to prevent processability deterioration due to a decrease in the amount of wax for the purpose of improving solution stability and applicability.

The wax compounding ratio was determined as the compounding ratio that showed the best frictional property as a result of the surface friction coefficient measurement. When the compounding ratio was 1: 1, the friction coefficient value was the lowest. Thus, the solution prepared by administering the main agent, the hardener and the additive wax and the chlorinated silica was chromated with a plating amount of 60/60 to 120/120 g / m ² (front / rear) and a chromium amount of 30 to 100 mg / m ² . A dry film thickness was applied to the surface of the hot-dip galvanized steel sheet using a bar coder with a thickness of 0.7 to 2.0 micrometers, then baked at a steel plate temperature of 120 to 180 ° C., followed by water cooling to prepare a coated resin coated steel sheet.

The amount of chromium deposition is closely related to the corrosion resistance of the lubricated resin coated steel plate. If the amount of chromium deposition is less than 30 mg / m ² , sufficient corrosion resistance cannot be expected. If the amount of chromium deposition is more than 100 mg / m ² , the film adhesion and workability are softened.

The dry film thickness of the resin is 0.7 to 2.0 micrometers because it is difficult to secure sufficient film properties when the film thickness is 0.7 or less, and when the film thickness is 2.0 or more, the film peeling phenomenon during processing adversely affects the corrosion resistance.

In addition, the temperature of the steel sheet is 120-180 ° C because the curing reaction of the resin does not sufficiently occur when the baking temperature is 120 ° C or lower, and at 180 ° C or higher, the properties of the baked hardened steel sheet cannot be preserved together with the material change of the steel sheet. .

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

Example 1

The imine ester resin is administered to the ester-urethane resin solution in the amount of 1 to 3 phr as a curing agent, and the pure water is adjusted so that the solution solid content is 10-20%.

To the solution prepared as described above was prepared a resin solution in which the clodal silica was added in about 10 to 15% of the solution amount as shown in Table 1. As a comparative material, each of the main solutions was changed into an acrylic urethane, an ether urethane, a polycarbonate diol, and a linear polyethylene resin, and a solution in which the above curing agents and additives were administered in the same manner was prepared.

In order to measure the surface contact angle of the prepared solution, the surface of the glass plate was completely degreased with acetone and sufficiently dried, and then each solution was taken with a syringe and dropped onto the glass plate surface to measure the angle between the droplet and the glass plate.

Contact angle measurements were measured five times for each solution using a contact angle gonimeter, and then averaged.

As shown in Table 1 below, the ester-urethane resin exhibits the smallest surface contact angle and the linear polyethylene resin exhibits the largest surface contact angle, but the polyethylene resin has a long molecular chain and a linear structure. Due to this strength, the contact angle is large because the polarity of the glass substrate is large.

According to the results of Table 1, in the case of steel plate coating having a large polarity property, the ester-urethane resin, which is an inventive material, has the best wettability to the steel plate and also shows excellent performance in actual coating properties, which is consistent with the results of surface contact angle measurement. .

Solution Classification Surface contact angle (°) Applicability Primary Secondary 3rd 4th 5th Average Invention Ester Urethane Resin ◎ 70 69 69.8 68 69.4 69.2 Comparative Material A Acrylic Urethane Resin △ 83 80 79.2 79.2 78.6 80 Comparative material B Ether Urethane Resin 74.4 76.4 76.2 76.4 77 76.1 ○ Comparative Material C Polycarbonate diol resin 81 80 80.8 81.2 80.4 80.7 △ Comparative Material D Linear polyethylene resin 90.6 92.4 90 93 92 91.9 ×

◎: Excellent ○: Good △: Normal ×: deterioration

Example 2

Melting point of the polyethylene-based wax with a melting point of 120 ℃ and non-polar functional group polyethylene wax with a melting point of 62 ℃ mixed in a ratio of 1: 1, and administered to the invention and comparative materials of Table 1 in the amount of 10 ~ 20phr relative to the main solids, respectively A solution was prepared, and the solution was dried on the surface of the hot-dip galvanized steel plate with the plating amount of 60/60 to 120/120 g / m ² (front / rear) and the chromium amount to be chromated to 30 to 70 mg / m ² . Was coated with a bar coater to a thickness of 0.7 ~ 2.0 micrometers and then baked at a steel plate temperature of 120 ~ 180 ℃ and then cooled by water to prepare a coated resin coated steel sheet.

Also, as a comparative material, a polyethylene wax having a melting point of about 100 ° C. was administered in the same amount as the contents of the invention material and the comparative material in Table 1 above to prepare a solution, and coated under the same conditions to prepare a coated resin coated steel sheet.

A friction coefficient measurement test using a draw bead tester was performed on the lubricated resin coated hot dip galvanized steel sheet prepared as described above.

As shown in the results of Table 2, when the two types of waxes were mixed, the surface friction coefficient was lower than that of the wax alone.

This is because the two waxes with different melting points have their respective properties in terms of molecular weight and physical properties, and when the two waxes are mixed with each other, they can exhibit excellent surface friction characteristics compared to the addition of wax alone. As shown, when the low melting point wax and the high wax were mixed in a ratio of 1: 1, the surface friction coefficient showed the lowest value, indicating that the workability was excellent.

Solution Classification Friction Count (μ) Comparative material Invention Invention Ester Urethane Resin 0.172 0.090 Comparative Material A Acrylic Urethane Resin 0.187 0.107 Comparative material B Ether Urethane Resin 0.190 0.104 Comparative Material C Polycarbonate diol resin 0.180 0.106 Comparative Material D Linear polyethylene resin 0.194 0.100

Example 3

Table 3 below shows the solution stability and chemical resistance of the ester-urethane resin as the main solution and the additives of cloidal silica and wax as shown in Tables 1 and 2, while varying the type and content of the curing agent. will be.

The solution stability was measured by measuring the viscosity change with time and the solution viscosity was rapidly increased, and the sludge was visually observed.

In addition, the chemical resistance was applied to the prepared solution under the same conditions as in Table 2 to prepare a lubricant resin coated steel sheet and after rubbing the methyl ethyl ketone solution about 10 times to evaluate the degree of surface peeling.

As shown in the results of Table 3 below, when 1-3phr of the imine-ester resin was added, excellent solution stability and chemical resistance were secured, whereas isocyanate resin and epoxy resin were found to have poor solution stability. When the amount of the imine ester was small, sufficient hardening did not occur, resulting in poor chemical resistance, while in many cases, solution stability was inferior due to an increase in reaction rate.

Purifier Solution stability Chemical resistance Invention Imine ester (1-3phr) More than 80 days ◎ Comparative Material A Isocynate (1 to 3 phr) 60 days ◎ Comparative material B Epoxy (1 to 3 phr) 50 days ◎ Comparative Material C Imine ester (0.5 phr) More than 80 days △ Comparative Material D Imine ester (4phr) 60 days ◎

◎: Excellent ○: Good △: Normal ×: deterioration

The present invention as described above is an excellent solution in the case of manufacturing a hot-dip galvanized steel sheet using a lubrication resin solution administered by administering the imine ester as a curing agent to the ester-urethane resin, a mixture of two waxes different from colloidal silica and melting point There is an effect of improving the quality by securing stability, processability and coating properties.

Claims (1)

A wax solution containing a polyethylene wax having a melting point of 125 ° C. and a non-polar functional group-substituted polyethylene wax having a melting point of 62 ° C. at a mixing ratio of 1: 1 is mixed with an ester-urethane resin solution with 1-3 phr of an imine ester resin as a curing agent. After adjusting by adding pure water so that the solution solid content is 10-20%, and then administering ammonia water so that the majesty is 9-10, and adding the cloidadal silica to the prepared solution about 10-15% of the solution amount After the wax solution was added to the solution administered in a content of 10-20 phr compared to the main solids, the thickness of the film was about 0.7-2.0 micrometers based on the dry coating weight on the coated chromate-treated hot dip galvanized steel sheet. Method of producing a resin-coated hot dip galvanized steel sheet using a lubricating resin solution, characterized in that by baking at a steel plate temperature of 120 ~ 180 ℃ after coating.

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