KR20080061731A - Low temperature curable cr-free pretreatment solution for organic coated steels, method for preparing pretreatment layer using the pretreatment solution, pretreatment layer prepared by the method and steel sheet comprising the pretreatment layer - Google Patents

Abstract

A solution for treating a surface of steel is provided to contain no heavy metal, to be baked at low temperature of 160 °C or below, and to ensure excellent corrosion resistance, resin adhesion, and solution stability. A solution for treating a surface of steel includes 1.0-20.0wt% of a resin mixture obtained by mixing urethane-based resin with acrylic resin in a weight ratio of 1:3-3:1, 0.1-5.0wt% of an alkylated melamine hardener, 1-10.0wt% of at least one organometallic oxide selected from the group comprising amine-based organic titanate and amine-based organic zirconate, 1.0-25.0wt% of a silicate mixture of at least one selected from the group comprising colloidal silica and metal silicate compounds, and the balance of a solvent.

Description

Low Temperature Curable Cr-free Pretreatment Solution for Organic Coated Steels, Low Temperature Curable Cr-Free Pretreatment Solution Composition for Resin Coated Steel Sheet, Pretreatment Layer Manufacturing Method Using the Composition, Pretreatment Layer by the Preparation Method, and Pretreatment Layer Method for Preparing Pretreatment layer using the Pretreatment Solution, Pretreatment layer prepared by the Method and Steel Sheet comprising the Pretreatment layer}

1 is a side cross-sectional conceptual view of a resin coated steel sheet including a chromium-free pretreatment layer.

The present invention relates to a low-temperature small-type chromium-free pretreatment solution composition for a resin coated steel sheet, a method for preparing a pretreatment layer using the composition, a pretreatment layer by the preparation method, and a steel sheet including the pretreatment layer, and a mixture of a urethane-based resin and an acrylic resin. At least one silicate mixture selected from the group consisting of at least one organo-metal oxide selected from the group consisting of alkylated melamine curing agents, amine-based organic titanates and amine-based organic zirconates, colloidal silica and metal silicate compounds And a resin solution composition for surface treatment of a steel sheet comprising a solvent, a method for preparing a pretreatment layer using the composition, a pretreatment layer prepared by the method, and a resin coated steel sheet comprising the pretreatment layer.

In general, when the resin is directly coated on the steel sheet, corrosion resistance and resin adhesion decrease due to a decrease in the affinity between the steel sheet and the resin layer, so that the pretreatment layer is required to be coated on the plated steel sheet before the resin coating to closely adhere the steel sheet and the resin. The required properties of the pretreatment layer require physical properties such as corrosion resistance, resin adhesion, steel sheet adhesion, and weldability, and application of a chromium-free pretreatment layer according to current environmental regulations. Heavy metals such as chromium, lead, mercury, and cadmium are harmful to the human body, and regulations on heavy metals in automobile and household steel sheets are being regulated mainly in the European Union and Japan. Especially, hexavalent chromium is harmful to humans. Known as Therefore, there is a need for an environmentally friendly resin coated steel sheet that does not contain these harmful heavy metals.

At present, the pre-treatment solution for pre-shielded steel sheet developed in Europe, etc., is a low temperature rinse (no-rinse) of PMT 80 ° C. It is mostly an acid solution and is composed of two components due to chemical instability, and is mixed and used in a production line before manufacturing. In addition, the composition of the present inventors Korean application No. 2005-0067392 contains an acrylic or epoxy resin, bentonite-based nanoclay powder, melamine-based curing agent, silicate, organic Ti or Zr oxide, but the ring-opening reaction of the epoxy resin As necessary, drying is possible at a temperature of about 80 ° C. or less, but since the curing reaction of the resin is completed at a high temperature of 220 ° C. or higher, there is a problem in that it is difficult to use for steel materials requiring low temperature baking such as BH steel sheets.

Low temperature baking during resin coated steel sheet reduces the amount of heat supplied to the steel sheet during baking and increases the production efficiency under a certain drying furnace length during production, and not only reduces the manufacturing cost of the resin coated steel sheet but also results in physical properties, namely tensile strength and Since high strength and light weight may be caused in steel sheets having different elongation, there is a need for a low temperature sintered chromium-free pretreatment solution composition and a resin coated steel sheet prepared using the same.

Accordingly, an object of the present invention is at least one organic-metal oxide, colloidal silica and metal selected from the group consisting of a mixture of urethane-based and acrylic resins, alkylated melamine curing agents, amine-based organic titanates and amine-based organic zirconates It is to provide a resin solution composition for surface treatment of a steel sheet comprising at least one silicate mixture and a solvent selected from the group consisting of silicate compounds.

Another object of the present invention is to provide a method for producing a pretreatment layer using the composition.

Another object of the present invention is to provide a pretreatment layer prepared by the above production method.

Another object of the present invention is to provide a resin coated steel sheet including the pretreatment layer.

According to one aspect of the invention, at least one organic-metal oxide selected from the group consisting of a mixture of a urethane resin and an acrylic resin, an alkylated melamine curing agent, an amine organic titanate and an amine organic zirconate, colloidal silica and Provided is a resin solution composition for surface treatment of a steel sheet comprising at least one silicate mixture selected from the group consisting of metal silicate compounds and a solvent.

According to another aspect of the invention, the solution composition is applied to a cold rolled steel sheet, zinc or zinc alloy plated steel sheet so that the dry coating thickness is 0.05 ~ 1.5 μm, baked at 60 ~ 160 ℃, then air-cooled or water-cooled resin coating Provided is a method for producing a steel sheet pretreatment layer.

According to another aspect of the present invention, a pretreatment layer produced by the above method is provided.

According to another aspect of the present invention, a resin coated steel sheet including the pretreatment layer is provided.

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

Physical properties of the resin coated steel sheet are mainly affected by the pretreatment layer and the resin layer. The pretreatment layer coating constituting the lower layer of the resin coated steel sheet has the effect of shielding against corrosion factors to secure the corrosion resistance of the resin coated steel sheet, to secure the adhesion to the steel sheet, and to secure the adhesion to the upper resin layer. Since the pretreatment layer does not secure such required characteristics, it does not achieve the intended corrosion resistance and workability of the resin coated steel sheet. In addition, the resin layer in the upper part of the steel plate ensures the corrosion resistance of the resin coated steel sheet and gives the required quality or color of the steel sheet due to the primary shielding effect against corrosion factors and the shielding effect to prevent sudden dissolution or loss of the lower pretreatment layer. It plays a role.

In order for the pretreatment layer coating to have an advantageous structure to secure the above-mentioned adhesion, the water-dispersible acrylic resin and the urethane resin were added to 1 to 20% by weight of the total solution in a weight ratio of 1: 3 to 3: 1, respectively. do. These resins have a hydrophilic group such as hydroxyl (-OH) constituting the coating film is advantageous for painting the resin layer on the top and serves as a binder that combines other additives.

The acrylic resin may be a resin having a number average molecular weight of 20,000 ~ 50,000. When the number average molecular weight of the acrylic resin is less than 20,000, it is more likely to react with the methylated amine titanate or the like than to react with the melamine resin, which is a curing agent, to cause sedimentation of the resin or to make the coating film too dense and easily to be removed, and the number average molecular weight is 50,000 or more. As the viscosity of the composition rises, it is difficult to form a uniform film and the drying temperature rises, resulting in poor workability during production, increasing the cleaning cost of the production equipment, and hardening at a temperature below 160 ° C. It is also economically advantageous to have a molecular weight to have a suitable viscosity. In addition, the acrylic resin may be made of a kind of monomer selected from the group consisting of n-butyl acrylate, methyl methacrylate, n-butyl methacrylate, and ethylene acrylate monomers.

In addition, the molecular weight of the urethane-based resin is preferably 50,000 to 100,000. If the molecular weight of the urethane-based resin is 50,000 or less, there is no effect of improving the workability, and if it is 100,000 or more, there is a problem that the stability of the solution decreases. In addition, the urethane-based resin may be prepared in one kind selected from the group consisting of isophorene diisocyanate, adipic acid, polyhydric alcohol.

In order to ensure smooth workability, it is preferable to use a resin dispersed in water or alcohol at 10 to 40% by weight rather than being used alone.

Melamine resin may be used as a curing agent for the acrylic or urethane resin. The melamine resin is particularly preferably a melamine-formaldehyde resin whose terminal is substituted with a methyl group, and is added at 0.1 to 5.0% by weight. If the content of the curing agent is less than 0.1% by weight, the curing reaction of the coating film may not be sufficient to secure the desired physical properties. If the content of the curing agent exceeds 5.0% by weight, there is no effect of increasing the curing reaction by additional addition. Rather, there exists a possibility of reducing solution stability and the physical property of a resin film. In particular, the curing agent is preferably added in 10 to 20% by weight relative to the resin content.

At least one silicate selected from the group consisting of colloidal silica and metal silicate compounds having a pH of 7.0 or more, preferably pH 7.0-10.0, is added in an amount of 1.0 to 25.0% by weight to improve the corrosion resistance and adhesion to the steel sheet. The metal silicate compound is preferably Li or Na, and the prepared resin is weakly alkaline at pH 8, and thus solution gelling occurs due to salt formation when colloidal silica having a pH of 5 or less is used. Thus, colloidal silica having a pH of 7 to 10 It is preferable to use because it is stable without sedimentation occurring. If it is 1.0 wt% or less, there is no improvement of adhesion and corrosion resistance, there is no effect of lowering the drying temperature, and even if it exceeds 25.0 wt%, there is no effect of improving corrosion resistance and adhesion due to silica addition, and it is buried in the roll surface during work, and the desired pretreatment layer for resin coated steel sheet This is because it is difficult to manufacture. It is preferable to use these silicate compounds dispersed in water or alcohol at about 10 to 30% by weight in terms of dispersibility.

At least one organo-metal oxide selected from the group consisting of amine organic titanate and amine organic zirconate added to the solution composition in an amount of 0.1 to 10.0% by weight serves as a catalyst for improving the binding force of colloidal silica. It also contributes to improved corrosion resistance and weldability. Preferably the amine organic titanate is methylated amine titanate and the amine organic zirconate is methylated amine zirconate. The organo-metallic compound may not be expected to act as a silica bonding catalyst at 0.1 wt% or less, and even when added at 10.0 wt% or more, it does not affect the role of the catalyst and the improvement of corrosion resistance, solution gelation may occur, and the cost is greatly increased. It is preferable to use these compounds disperse | distributed about 40 to 60 weight% in water.

Preferably, at least one water dispersible nanoclay selected from the group consisting of bentonite and monteronite may be added to improve the corrosion resistance of the pretreatment layer. The nanoclay has high alkalinity, expands to more than several times its volume by inhalation of water, exhibits strong viscosity, has no precipitation even when left for a long time, and is used as a paint or coating agent because it has a property of making a smooth film. Since the nanoclay aqueous dispersion has a triple plate-like structure of silicate-aluminum-silicate, it is possible to achieve excellent corrosion resistance by improving the blocking function of materials against gases such as oxygen, carbon dioxide, chlorine compounds or organic solvents. The hygroscopicity also improves the dispersibility of the entire solution.

The nanoclay is 0.05 ~ 5.0% by weight based on the total solution, but when the nanoclay itself is mixed with the solution is difficult to disperse 0.5-15 parts by weight of nanoclay per 100 parts by weight of water for effective dispersion It can be used by dispersing. That is, if the nanoclay is added directly to the solution, the nanoclay absorbs the liquid component, the viscosity may be rapidly increased, and solution coagulation may occur. Therefore, it is preferable to add a solution previously dispersed in water or alcohol. If the content of nanoclay is less than 0.05% by weight, there is no significant effect on the improvement of corrosion resistance due to insufficient shielding effect. If the content is more than 5.0% by weight, the viscosity of the whole solution is greatly increased, and the hardness of the pretreatment film is increased after baking. It is not preferable because it causes coating swelling, uneven coating, incompletely coated spots, and desquamation by lowering adhesion to the upper resin. It is preferable to disperse | distribute the said nanoclay independently, or to inject the solution which peeled off with 0.5-2.0 weight part of 2-amino-2-methyl-1- propanols per 100 weight part of solvents, and 2-amino-2-methyl -1-propanol exhibits the dispersion catalyst effect of the nanoclay aqueous solution and improves the stability of the dispersion solution when dispersing 1.0 wt% or more of nanoclay in water.

Optionally at least one dispersant selected from the group consisting of polyether modified polydimethylsiloxanes and hydroxylated carboxylic acid esters, or agitation of the solution or in a coater pan to improve the wetting of the resin solution composition A siloxane antifoaming agent for removing the bubbles formed by the can be optionally added. These additives may be at least one kind selected from the group consisting of dispersants and vesicles, and are preferably added in an amount of 0.1 to 3.0% by weight based on the total solution. When the dispersing agent or the antifoaming agent is 0.1 wt% or less, the dispersion effect of the solution is inadequate, so that there is no wettability and the defoaming effect is insufficient, so bubbles are easily transferred to the roll or the like during the operation and unpainted on the surface of the steel sheet. When the wettability of the solution is excessively increased, it is difficult to control the amount of adhesion during coating of the pretreatment solution, and the solution stability due to the excessive antifoaming agent is lowered.

In addition, in order to disperse and quick-dry the resin solution, alcohol may be added in an amount of 1 to 20 wt% based on water, which is the main solvent. The alcohol causes the solution to dry quickly and acts as a solvent in the solution with water to aid dispersion. However, when more than 20% by weight is added, the solid content of the solution is rapidly increased due to the evaporation of alcohol, thereby decreasing the coating workability and increasing the evaporation rate of the solvent, thereby adversely affecting the formation of craters in the coating film. The alcohol may be used by mixing one or more alcohols selected from ethanol, isopropanol, butyl alcohol, and the like.

According to the present invention, a method for producing a resin coated steel sheet pretreatment layer using the resin composition is provided.

By applying the resin composition of this invention on a cold rolled steel plate or a galvanized steel sheet, the pre-processed film layer for resin coated steel sheets which is excellent in corrosion resistance, adhesiveness, and weldability is manufactured.

As the plated steel sheet, a galvanized steel sheet or a zinc alloy plated steel sheet may be used. Various methods such as electroplating, hot-dip plating, and vacuum deposition may be used as a method of plating a zinc alloy mixed with zinc on a steel sheet or zinc and other metals such as iron, nickel, and cobalt.

The resin composition of the present invention is coated on the plated steel sheet so that the dry coating film has a thickness of 0.05 to 1.5 µm, and then fired or cooled by baking at a steel sheet temperature of 60 to 160 ° C. If the thickness of the dry coating film is less than 0.05 µm, corrosion resistance, resin adhesiveness, and the like are lowered. If it exceeds 1.5 µm, the weldability is reduced and the production cost is increased.

The total solids content of the solution consisting of the above components is preferably maintained at 5-20%. If the solid content is 5% or less, the thickness of the humidity film for obtaining the desired dry film thickness is increased, so that smooth drying is not achieved during the drying process, so that it is difficult to obtain a uniform surface and the drying temperature must be increased. In this case, the sedimentation rate of the solution increases, so that the stability of the solution may decrease, and the phenomenon of over-attachment may occur, making it difficult to control the amount of adhesion.

The resin solution composition of the present invention is used to prepare a pretreatment layer for a preshielded steel sheet composed of an organic-inorganic composite component. The pretreatment layer prepared by the resin solution composition of the present invention improves the corrosion resistance and resin adhesion of the resin component and reduces the drying temperature. It has an effect, and corrosion resistance and adhesiveness improve by silica, corrosion resistance improvement and solution stability are ensured by the nanoclay blocking effect, corrosion resistance and weldability are improved by organic Ti component, and adhesion amount analysis is easy. In addition, the coupling agent ensures adhesion to the base steel sheet, the dispersing agent facilitates the coating operation and resin coating properties.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the following Examples do not limit the present invention.

<Example 1>

In this example, the solution stability of the resin solution and the physical properties of the resin coating were evaluated according to the content and molecular weight of the acrylic resin and urethane resin, and the content of the curing agent.

An acrylic resin having a number average molecular weight of 30,000 was prepared from a kind of monomer selected from the group consisting of n-butyl acrylate, methyl methacrylate, n-butyl methacrylate and ethylene acrylate monomers. A urethane-based resin having a number average molecular weight of 80,000 was prepared as a kind of monomer selected from the group consisting of urethane-based isophorene diisocyanate, adipic acid, and polyhydric alcohol. The curing agent used an alkylated melamine formaldehyde curing agent (Cytek Corporation Cymel 308). At this time, the quality characteristics were evaluated by adjusting the ratio and content of the acrylic resin and urethane resin, and the content of the curing agent. The content of Example 1 represents the total weight percentage in the solution of solids except water and alcohol.

Examples of the additive of Example 1 were 10% by weight of colloidal silica (Snowtex-40 from Nissan Chemical), 5% by weight of amine organic titanate (Tyzor TE® from Dupont). 0.1 wt% of bentonite-based nanoclay powder dispersed in water and 0.5 wt% of siloxane-based dispersant (Ciba EFKA 3580) were added, respectively. Solid content concentration of the surface treatment composition was about 15% by weight. For reference, water was used as the main ingredient except solids, and 5 wt% of ethanol relative to water was added as an alcohol solvent to prepare solution compositions of Inventive Examples 1-11 and Comparative Examples 1-12.

Thereafter, solution stability, corrosion resistance, weldability, post-adhesion adhesion and processability to the solution composition were evaluated.

Solution stability was evaluated according to the volume fraction of the precipitate after 7 days at room temperature and the presence of gel formation in the solution composition after 30 days at room temperature in consideration of sufficient time to be actually used.

◎ a case where no precipitate is formed and no gel is formed, △ when a precipitate is generated at 2 vol% or more, or △, a precipitate is generated at 5 vol% and a gel is formed.

Corrosion resistance and weldability of the bar coater to the dry coating thickness of 0.2㎛ each of the resin composition on the electro-galvanized and zinc-alloy plated steel sheet having a thickness of 0.65 ~ 0.75mm prepared with a coating weight of 40 ~ 60g / m ² ), And then baked at 90 ° C steel plate temperature and then cooled to prepare a specimen.

Corrosion resistance was investigated by using a salt water spray tester (SST) at 35 ° C and the occurrence time of corrosion of more than 5% of white blue and red blue according to the elapsed time was investigated.

◎: Red blue color: Over 96 hours, White blue color over 48 hours

○: Red Blue: 72 ~ 96 hours, White Blue 24 ~ 48 hours

□: Red blue: 48 ~ 72 hours, White blue 12 ~ 24 hours

△: Red blue occurrence: 24 ~ 48 hours, White blue occurrence within 12 hours

×: Red blue: within 24 hours

In order to evaluate the weldability, each specimen was welded using an AC pneumatic spot welding machine under a pressurization of 250 kgf and an energization time of 16 cycles at a welding current of 8 kA. RWMA Class II of Cu—Cr alloy was used as the welding electrode. Weldability was evaluated by continuous RBI. The test specimens were overlapped to the point of 20mm from the end of the two specimens cut to 80mm in length, 20mm in width, one point welding in the middle of the overlapping area and then the number of spots of the weld drop by the tensile tester was investigated. The RBI was evaluated as the number of consecutive RBIs and the evaluation criteria are as follows.

◎: More than 1,200 consecutive RBIs

○: Number of consecutive RBI 1,000 ~ 1,200

□: Number of consecutive RBI 800 ~ 1,000

△: 800 or less consecutive RBIs

×: No welding

Using a bar coater, a pre-shielded resin solution (Bumwoo Chemical POS-sealed product, hereinafter referred to as 'pre-shielded resin') was placed on top of the pretreatment layer prepared to evaluate resin adhesion. After coating so as to be baked at 150 ~ 280 ℃, the water-cooled and dried specimens were taken in a size of 30mm X 50mm, immersed in boiling water for 30 minutes and dried to measure the degree of peeling using a Scotch Tape. The evaluation was performed according to the degree of resin buried in the tape, the evaluation criteria are as follows.

◎: No stripping on tape surface

□: Peeling within 5% of area ratio

△: 박리 5% or more peeling occurred on the surface of tape

×: All surfaces peeled off the tape surface

Machinability was evaluated by peeling a circular specimen with a diameter of 95mm, forming a cup with a height of 25mm, and then using a scotch tape on the side of the side with the most severe processing. The evaluation criteria are as follows.

◎: No stripping on tape surface

□: Peeling within 5% of area ratio

△: 박리 5% or more peeling occurred on the surface of tape

Table 1

division Resin composition (% by weight) Resin Content (wt%) Curing agent content (% by weight)  Quality characteristic urethane acryl Solution stability Corrosion resistance Weldability Resin adhesion Machinability Comparative Example 1 0 0 0.5 5 ◎ △ ○ □ x Comparative Example 2 80 20 5 5 ○ ○ △ □ □ Inventive Example 1 75 25 10 5 ◎ ◎ ◎ ◎ ◎ Inventive Example 2 70 30 10 5 ◎ ◎ ◎ ◎ ◎ Inventive Example 3 65 35 10 5 ◎ ◎ ◎ ◎ ◎ Inventive Example 4 60 40 10 5 ◎ ◎ ◎ ◎ ◎ Inventive Example 5 50 50 10 5 ◎ ◎ ◎ ◎ ◎ Inventive Example 6 45 55 10 5 ◎ ◎ ◎ ◎ ◎ Inventive Example 7 40 60 7 3 ◎ ◎ ◎ ◎ ◎ Inventive Example 8 25 75 10 5 ◎ ◎ ◎ ◎ ◎ Comparative Example 3 20 80 10 5 ○ △ ◎ ◎ x Comparative Example 4 10 90 10 5 ○ △ ◎ □ x Inventive Example 9 50 50 15 5 ◎ ◎ ◎ ◎ ◎ Inventive Example 10 50 50 10 3 ◎ ◎ ◎ ◎ ◎ Comparative Example 5 50 50 3 0 x ○ ○ x ◎ Comparative Example 6 50 50 0 5 ◎ x x △ △ Comparative Example 7 50 50 5 8 x ◎ △ ◎ □ Inventive Example 11 60 40 8 2 ◎ ◎ ◎ ◎ ◎ Comparative Example 8 70 30 25 5 ○ x △ ◎ □ Comparative Example 9 50 50 25 0 x △ ○ □ □ Comparative Example 10 50 50 0.5 5 ◎ △ ◎ x □ Comparative Example 11 50 50 5 10 ◎ △ ○ ◎ ◎ Comparative Example 12 50 50 50 10 ◎ △ ◎ □ x

<Example 2>

Acrylic resin and urethane resin shown in Inventive Example 4 of Example 1. To the composition of the melamine curing agent, the content of colloidal silica, methylated amine titanate, dispersant, and bentonite-based nanoclays were changed and blended in the amounts shown in Table 2, respectively. After preparing the composition, the solution stability according to the change of the content of these additives was evaluated. After that, the adhesion, resin adhesion and weldability were evaluated.

Solution stability, corrosion resistance, weldability, resin adhesiveness and workability were evaluated in the same manner as in Example 1.

TABLE 2

 division Additive content (% by weight) Quality evaluation Silica Organometallic oxide Dispersant Nanoclay Dispersion Solution stability Corrosion resistance Weldability Resin adhesion Machinability Comparative Example 13 0 0.1 0 0 ◎ x ◎ x x Comparative Example 14 One 0 0.1 0.2 ◎ □ ○ △ △ Inventive Example 12 5 0.2 0.5 0.5 ◎ ◎ ◎ ◎ ◎ Comparative Example 15 5 3.5 2.0 0 ○ ◎ ◎ □ x Inventive Example 13 5 0.5 3.0 20 ◎ ◎ ◎ ◎ ◎ Comparative Example 16 10 4.0 5.0 55 x ○ □ ◎ ◎ Comparative Example 17 10 1.0 10.0 2.0 △ ○ □ ◎ ◎ Comparative Example 18 10 5.0 0 3.0 △ ◎ □ □ △ Inventive Example 14 10 0.5 1.0 45 ◎ ◎ ◎ ◎ ◎ Inventive Example 15 10 1.0 2.0 5 ◎ ◎ ◎ ◎ ◎ Inventive Example 16 10 3.0 3.0 20 ◎ ◎ ◎ ◎ ◎ Comparative Example 19 15 1.5 4.0 5.0 ◎ ◎ ◎ △ x Comparative Example 20 15 5.0 5.0 0.2 □ ○ ◎ ◎ ◎ Comparative Example 21 15 2.0 8.0 0.5 ◎ ◎ ◎ □ △ Comparative Example 22 20 7.0 10.0 0 △ ◎ ◎ △ x Inventive Example 17 20 0.5 0.5 2.0 ◎ ◎ ◎ ◎ ◎ Comparative Example 23 20 15.0 2.0 60 x ◎ ◎ □ x Comparative Example 24 25 3.0 5.0 2.0 △ ◎ ◎ ◎ ◎ Comparative Example 25 25 10.0 8.0 3.0 △ ◎ ◎ △ x Comparative Example 26 25 0.1 10.0 55 x ◎ ○ △ x Comparative Example 27 30 0 0.5 5 x ◎ □ ◎ ◎ Comparative Example 28 30 0.2 2.0 0.5 △ △ □ ◎ ◎ Comparative Example 29 30 3.5 5.0 0 □ △ △ □ x

<Example 3>

In the present embodiment, the resin composition is prepared on the base steel sheet, which is a zinc alloy plated or electroplated steel plate with a coating weight of 40 to 60 g / m ² having a thickness of 0.7 mm. After the resin coating at the baking temperature and dry coating film thickness shown in Table 3, using the comparative material and the invention material, the corrosion resistance, weldability, resin adhesion and workability were evaluated.

TABLE 3

 division  Manufacture conditions  Quality evaluation Baking temperature (℃) Coating thickness (㎛) Corrosion resistance Adhesion Adhesion after processing Weldability Comparative material 50 0.2 △ x x ◎ Comparative material 80 0.01 x △ ◎ ◎ Invention 80 0.23 ◎ ◎ ◎ ◎ Invention 100 0.5 ◎ ◎ ◎ ◎ Comparative material 120 0.03 x ◎ ○ ◎ Comparative material 140 1.8 ◎ ○ □ x Invention 120 1.0 ◎ ◎ ◎ ◎ Invention 140 0.8 ◎ ◎ ◎ ◎ Invention 160 0.1 ◎ ◎ ◎ ◎ Comparative material 180 1.2 ◎ ○ □ △ Comparative material 200 0.2 ◎ ○ ○ ◎

The pretreatment coating film for the resin coated steel sheet of the cold rolled steel sheet, galvanized steel sheet or zinc alloy plated steel sheet produced by the solution composition and the pretreatment layer manufacturing method of the present invention has excellent solution stability and corrosion resistance by mixing acrylic resin and urethane resin, It shows excellent weldability, resin adhesiveness and workability after resin coating on the upper part, and is a pre-shielded steel plate used for the part where it is difficult to form phosphate coating or electrodeposition coating film such as the rear part of automobile body or the heme It is suitable for use in the pretreatment layer of resin coated steel sheets.

Claims (14)

At least one organo-metal oxide selected from the group consisting of urethane-based and acrylic resin mixtures, alkylated melamine curing agents, amine-based organic titanates and amine-based organic zirconates, colloidal silica and metal silicate compounds A solution composition for surface treatment of a steel sheet, comprising at least one silicate mixture and a remainder of solvent. According to claim 1, 1.0 to 20.0% by weight of a resin mixture of a urethane-based resin and acrylic resin in a weight ratio of 1: 3 to 3: 1, 0.1 to 5.0% by weight of an alkylated melamine curing agent, amine organic titanate and amine organic 1 to 10.0 wt% of at least one organo-metal oxide selected from the group consisting of zirconates, 1.0 to 25.0 wt% of at least one silicate mixture selected from the group consisting of colloidal silica and metal silicate compounds having a pH of 7.0 to 10.0 Solution composition for surface treatment of the steel sheet comprising a. The acrylic resin of claim 1, wherein the acrylic resin has a number average molecular weight of 20,000 to 50,000, and is prepared from a monomer selected from the group consisting of n-butyl acrylate, methyl methacrylate, n-butyl methacrylate, and ethylene acrylate monomers. A solution composition for surface treatment of a steel sheet. The solution composition for surface treatment of a steel sheet according to claim 1, wherein the urethane-based resin has a number average molecular weight of 50,000 to 100,000, and is prepared from one selected from the group consisting of isophorene diisocyanate, adipic acid and polyhydric alcohol. The solution composition for surface treatment of a steel sheet according to claim 1, wherein the resin, silicate mixture or organo-metal oxide is added in a dispersed form in water or alcohol. The solution composition for surface treatment of a steel sheet according to claim 1, wherein the solvent is water or water added with 10 to 20% by weight of alcohol. The solution composition for surface treatment of a steel sheet according to claim 1, further comprising 0.05 to 5.0 wt% of at least one nanoclay selected from the group consisting of bentonite and montmonite. 8. The solution composition for surface treatment of a steel sheet according to claim 7, further comprising 0.5 to 2.0 parts by weight of 2-amino-2-methyl-1propanol per 100 parts by weight of the solvent together with the nanoclay. The method according to claim 7 or 8, wherein at least one nanoclay selected from the group consisting of bentonite and montmonite, or the nanoclay added with 2-amino-2-methyl-1propanol is added to water or alcohol. A solution composition for surface treatment of a steel sheet, which is added in a dispersed form. The solution composition for treating a surface of a steel sheet according to claim 1, wherein the resin solution further comprises 0.1 to 3.0% by weight of at least one selected from the group consisting of a dispersant and an antifoaming agent. The solution for surface treatment of a steel sheet according to claim 10, wherein the dispersant is at least one selected from the group consisting of polyether-modified polydimethylsiloxane and hydroxylated carboxylic acid ester, and the endoplasmic reticulum is a silane based vesicle. Composition. The solution composition of any one of claims 1 to 11 is applied to a cold rolled steel sheet, a zinc or zinc alloy plated steel sheet such that the dry coating thickness is 0.05 to 1.5 μm, and baked at 60 to 160 ° C., followed by air cooling or water cooling. Resin coated steel sheet pre-treatment layer manufacturing method. The solution composition of any one of claims 1 to 11 is applied to a cold rolled steel sheet, a zinc or zinc alloy plated steel sheet such that the dry coating film thickness is 0.05 to 1.5 μm, and then baked at 60 to 160 ° C., followed by air cooling or water cooling. Resin-coated steel sheet pretreatment layer prepared by. The solution composition of any one of claims 1 to 11 is applied to a cold rolled steel sheet, a zinc or zinc alloy plated steel sheet such that the dry coating film thickness is 0.05 to 1.5 μm, and then baked at 60 to 160 ° C., followed by air cooling or water cooling. Resin coated steel sheet comprising a pretreatment layer prepared by.

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