KR100262495B1 - Polyurethane resin solution composition having good lubricating and workability and its uses for the preparation of surface treatment of steel plate - Google Patents

Abstract

PURPOSE: An aqueous polyurethane resin composition is provided for accomplishing excellent lubricating ability and workability of the steel sheet coated with the resin composition by containing polyol and a specific component selected from sulfonate diamine and diol, dihydroxy carboxylic acid and a,a'-diphenylol propionate. CONSTITUTION: The aqueous polyurethane resin composition having excellent lubricating ability and workability of the steel sheet as coated with the resin composition comprises aqueous polyurethane resin solution; 3-30 weight parts of the lubricating agent such as olefine wax or polyethylene wax; 10-50 weight parts of silica; 0.1-2.5 weight parts of silane coupling agent and 5-30 weight parts of hardening agent selected from polyfunctional aziridine, carbodiimide methoxymethylol substituted MMMF and urea formaldehyde resin in terms of the total weight of the resin composition. The steel sheet is surface treated by coating with the resin composition in a dry thickness of 0.5-4.0 micrometers, baking it at 80-140 deg.C. and cooling the resultant product.

Description

Aqueous polyurethane resin solution composition with excellent lubricity and workability and method for producing surface-treated steel sheet using the same

The present invention relates to a method for producing a surface-treated steel sheet using an aqueous polyurethane resin solution composition and a resin solution composition used in home appliances, building materials, or automotive surface-treated steel sheet, and more particularly, a urethane resin solution having excellent lubricity and workability. And it relates to a method for producing a surface-treated steel sheet by applying it.

Zinc or zinc-based alloy plated steel sheets used in applications requiring corrosion resistance, such as home appliances, building materials, and automobiles, are usually shipped with steel or coils coated with rust-preventive oil to prevent rust generation during flow and storage for a period of time. These steel sheets may be processed as they are or may be processed after coating with processing oil. However, there are problems such as contamination of the working environment due to scattering of processing oil during oiling, deterioration of image processing due to poor degreasing in the next degreasing treatment process, and poor coating.Therefore, organic solvents used in the degreasing process are used. It has been a cause of causing environmental problems such as ozone layer destruction as well as environmental pollution and fire hazard in the workplace.

In order to solve this problem, conventionally, methods for increasing the press formability by providing lubricity to the resin solution itself have been developed. For example, Japanese Patent Application Laid-Open No. 5-138120 suggests a method for producing a galvanized steel sheet treated with a lubricating solution based on a thermosetting solvent-based resin. As suggested in 3-71836 and 3-16726, a lubricating solution for lubricating a steel sheet has been proposed. However, the above methods have a disadvantage in that the use of solvent-based resins or general-purpose resins can not reduce the pollution problem due to fire risk, deterioration of working environment and solvent volatility as well as compatibility with additives. In addition, in the case of the domestic application No. 40099 and 40100 is made of a water-soluble resin to improve some of the above problems, there is a problem in that a small amount of the remaining solvent is volatilized when the resin is produced, the stability of the solution is degraded, the workability is deteriorated.

Accordingly, the present invention has been proposed to solve the above problems, and an object of the present invention is to provide a urethane resin solution having excellent lubricity as well as workability, such as workability of steel sheet and stability of solution, and a method of manufacturing a surface-treated steel sheet using the same. To provide.

In one aspect of the present invention, a lubricant comprising (a) an aqueous polyurethane resin solution; one or two selected from (b) paraffin wax, olefin wax and polyethylene wax based on 100 parts by weight of resin solid content 3-30 parts by weight; (c) 10-50 parts by weight of colloidal silica or fumed silica; (d) 0.1-2.5 parts by weight of a silane coupling agent selected from epoxy, amino and methacrylic silane coupling agents; and ( e) 5-30 parts by weight of a curing agent selected from polyfunctional aziridin-based, carbodiimide-based, melamine formaldehyde (MMMF) resins substituted with methoxymethylol and urea-formaldehyde resins There is provided a polyurethane resin solution composition.

Further, in another aspect of the present invention, the polyurethane resin solution composition of the present invention is applied to a steel sheet so that the dry film thickness is 0.5-4.0 μm, and after baking at a steel plate temperature of 80-140 ° C. Provided is a method for producing a cooled surface treated steel sheet.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

As used herein, the term "parts by weight" used as a term indicating the amount of each component is based on the solids content of each component, and each component is added based on 100 parts by weight of the resin solids.

The polyurethane resin solution is a sulfonate diamine and a diol, a dihydroxy carboxylic acid system and a, a'-diphenylolpropionyl acid which provide a hydrophilic group for the solubility of polyol and isocyanate and resin. It is prepared by accommodating a polyurethane resin prepared by polymerizing at least one kind of component selected from the group consisting of (DMPA) and adjusting the amount of resin solid by adding water thereto.

In this case, polyester or polyepoxy containing 5-30% by weight of an aromatic polyol having a molecular weight of 2000-5000 is used as the polyol, and 4,4'-diphenylmethane diisocyanate, 2,4-toluenediisocysia isocyanate. Aromatic isocyanates such as amides and aliphatic diisocyanates are used in a 1: 3-5 weight ratio based on the polyol.

On the other hand, the components selected from sulfonate diamine and diol, dihydroxy carboxylic acid system and a, a'-diphenyl olpropionyl acid (DMPA) which provide a hydrophilic group necessary for solubilization are polymerized resins. It is used so that 5-30 weight part with respect to 100 weight part. The polyurethane resin thus polymerized is solubilized by adding a neutralizing agent selected from the group consisting of dimethylethanolamine, triethylamine and ammonia water to neutralize, and adjusting the amount of the solid resin by adding water after neutralization. Urethane resin solution is prepared.

In order to improve the lubricity and workability of the polyurethane resin solution, a lubricant, silica, a silane coupling agent and a curing agent are added to the resin solution.

By adding a lubricant to the polyurethane resin solution, the self-lubrication of the resin solution is improved. Examples of the lubricant include paraffin wax (melting point 55-75 ° C), olefin wax (melting point 75-110 ° C), polyethylene wax (melting point 100-125 ° C), and one or two or more of them are mixed. Can be added. The amount of lubricant added is preferably added 3-30 parts by weight based on 100 parts by weight of the resin solid content.

If the amount of lubricant added is less than 3 parts by weight relative to the resin solids, the lubrication effect is not sufficient, and when more than 30 parts by weight is added, the lubrication effect is not exerted, and the required performance and solution stability of the lubricant coated steel sheet are lowered. .

Moreover, corrosion resistance improves by adding a silica to a polyurethane resin solution. Colloidal silica or fumed silica is used as silica, and the addition amount is preferably 10-50 parts by weight based on 100 parts by weight of the resin solids.

When silica is added less than 10 parts by weight, the effect of improving corrosion resistance does not appear remarkably, and when it is added more than 50 parts by weight, no further improvement of corrosion resistance is shown. Rather, the film is scratched by silica during processing, which is disadvantageous to corrosion resistance. Works.

A silane coupling agent is also added to fix the polyurethane resin and silica to improve workability and corrosion resistance. Epoxy-based, amino-based and methacryl-based silane coupling agents are used as the silane coupling agent, and examples thereof include γ-glycerideoxypropyl ethoxysilane, γ-aminopropyl triethoxysilane, and γ-methoxyoxypropyl tri. Methoxysilane etc. are mentioned. The silane coupling agent is preferably added at 0.1-2.5 parts by weight based on 100 parts by weight of the resin solids. When added at less than 0.1 part by weight, the effect of the silane coupling agent does not appear, and when added at 2.5 parts by weight or more, the stability of the solution decreases rapidly.

On the other hand, by adding a curing agent to the polyurethane resin solution can be crosslinked to an appropriate level to obtain the required physical properties. In this case, a curing agent such as a polyfunctional aziridine system, a carbodiimide system, a melamine formaldehyde (MMMF) resin system substituted with methoxymethylol, or an urea formaldehyde resin system is used. The type and amount of the curing agent may be changed depending on the properties of the lubricated coated steel sheet required, but it is preferable to add 5-30 parts by weight of the curing agent based on 100 parts by weight of the resin solid content. If the amount of the curing agent is less than 5 parts by weight, it is difficult to obtain the required physical properties because it is not sufficiently cured.In the case of more than 30 parts by weight, the excessive hardening reaction not only lowers the workability and adhesion to the steel sheet but also gels the solution, resulting in rapid solution stability. Degrades.

Hereinafter, a method for manufacturing a surface-treated steel sheet using the polyurethane resin solution composition of the present invention will be described in detail.

The polyurethane resin solution composition prepared as described above may be commonly applied to a steel plate treated with chromate to prepare a surface treated steel sheet. After the resin solution is coated on the steel sheet with a dry coating thickness of 0.5-4.0 µm, the resin solution is baked at a steel sheet temperature of 80-140 ° C., and then dried by air cooling or water cooling to prepare a surface treated steel sheet.

When baking the resin solution composition on a steel sheet and baking at 80 ° C. or less, the curing reaction of the resin is not properly performed, so it is difficult to expect the effect of the coating film. When the baking is performed at 140 ° C. or more, the film may be peeled off. It is preferable to bake so that the temperature of the baked steel sheet is 80-140 ° C.

In addition, when the thickness of the dry coating film after baking is 0.5 μm or less, the workability is poor, and the galvanized steel sheet tends to turn black. It is preferable to coat so that it is 0.5-4.0 micrometers.

EMBODIMENT OF THE INVENTION Hereinafter, the Example of this invention is described.

EXAMPLE

To the aqueous polyurethane resin solution having a solid content of 15% by weight, a lubricant (addition of olefin wax and polyethylene wax in the same amount) was added in the amount shown in Table 1 below, followed by sufficient stirring, followed by melamine substituted with methoxymethylol as a curing agent. The polyurethane coating solution composition of Example 1-9 and Comparative Example 1-9 was added by adding 20 parts by weight of formaldehyde resin and colloidal silica and γ- glycidoxy propyl triepoxy silane coupling agent in the amounts shown in Table 1 below. Was prepared. As the base steel sheet, chromium-plated 40 mg / m ² , zinc-plated 20/20 g / m ² and 0.8 mm thick chromate-treated electrogalvanized steel sheets were used. The polyurethane resin solution was applied to the steel sheet using a roll coater, and then baked in a heating drying furnace at the baking temperature shown in Table 1, and immediately taken out and water-cooled.

The physical properties of the surface treated steel sheet were measured by the following method, and the test results are shown in Table 1 below.

[Friction coefficient]

Friction coefficient was measured by the Drawbead Tester (Drawbead Tester) at room temperature, the coefficient of dynamic friction, the smaller the coefficient of friction shows that the better the lubricity. The characteristics were compared based on the following numerical values.

Friction Coefficient Evaluation (μ) ◎: Less than 0.080 O: 0.080-0.089

△: 0.090-0.099 ×: 0.1 or more

(Processability-Blank Holding Force)

Workability evaluation was performed by measuring the maximum blank holding force (BHK-Blank Holding Force) of each specimen during cup forming with a drawing ratio of 1.96 using a thin plate comprehensive tester.

Machinability Evaluation (Ton) ◎: Over 35 O: 25-34

△: 10-24 ×: less than 10

(Fingerprint resistance)

Anti-fingerprint was measured with a CIE Lab type color difference meter (TOKYO DENSHOKU CO.) And the change in color difference (ΔE) before and after the application of petrolatum on the steel sheet was measured.

Anti-fingerprint (ΔE) ◎: Less than 1.0 O: 1.0-2.0

△: 2.1-3.0 ×: 3.0 or more

(Stone resistance)

Corrosion resistance was evaluated by using the salt spray tester until the time when the white area was less than 5%.

White rust occurrence time (hrs) ◎: Over 420 O: 360-420

△: 300-360 ×: 300 or less

TABLE 1

Evaluation result of quality characteristics by solution composition

However, each said additive is added so that solid content of each component may be weight part of each described amount based on 100 weight part of solid content of aqueous polyurethane resin solution.

As shown in Table 1, when the addition amount and treatment conditions of the various additives to the polyurethane resin system is treated within the scope of the present invention, it exhibits excellent physical properties while sufficient when the baking temperature is low, as in Comparative Examples 1 and 2. As purification did not occur, workability and corrosion resistance were lowered, and fingerprint resistance was deteriorated, and in the case of fine particles, the resin film was partially peeled off during processing. In Comparative Examples 3 and 4, when the amount of the wax added as a lubricant was low, the workability was inferior, and in the case of a large amount, the solution stability was lowered. In the case of Comparative Materials 5 and 6, when a small amount of silica was added, the corrosion resistance was significantly decreased. When a large amount was added, scratches occurred on the film itself during processing. In addition, in the case of Comparative Materials 7, 8, when a small amount of the silane coupling agent was added, the corrosion resistance and the workability were lowered, and when a large amount was added, the solution stability was lowered. When only resin was applied as in Comparative Example 9, it was evaluated that workability and corrosion resistance were very poor.

Claims (4)

(a) aqueous polyurethane resin solution; (B) 3-30 parts by weight of one or two selected from paraffin waxes, olefin waxes and polyethylene waxes, based on 100 parts by weight of the resin solid; (c) colloidal silica or fumed silica. 50 parts by weight; (d) 0.1-2.5 parts by weight of a silane coupling agent selected from epoxy, amino and methacrylic silane coupling agents; and (e) polyfunctional aziridine-based, carbodilmide 5-30 parts by weight of a curing agent selected from a melamine formaldehyde (MMMF) resin system and a urea formaldehyde resin system charged with methoxymethylol); an aqueous polyurethane resin solution composition. The 4,4'-diphenylmethane according to claim 1, wherein the aqueous polyurethane resin solution is a polyester containing 5-30% of an aromatic polyol having a molecular weight of 2000-5000 as a polyol or an aromatic diisocyanate as a polyepoxy and an isocyanate. Diisocyanate and 2,2-toluenediisocyanade and aliphatic diisocyanate in a 1: 3-5 weight ratio; and based on 100 parts by weight of resin solids, sulfonatediamine, sulfonatediol, dihydride, which provides the hydrophilic groups required for solubilization It is prepared by dissolving a polyurethane resin prepared by hydroxycarboxylic acid type or a, a'-diphenylolpropionic acid by polymerizing at least one component selected from 5 to 30 parts by weight based on 100 parts by weight of the polymerization resin. Modified polyurethane resin solution composition, characterized in that. The aqueous polyurethane resin solution composition according to claim 1, wherein the silane coupling agent is γ- glycidoxy propyl triethoxysilane, γ-aminopropyl triethoxysilane, and γ-methoxyoxypropyl trimethoxysilane. A method for producing a surface-treated steel sheet which is coated on a steel sheet with the aqueous polyurethane resin solution composition of claim 1 so as to have a dry film thickness of 0.5-4.0 μm, and baked after baking at a steel plate temperature of 80-140 ° C.