KR102035591B1 - Composition for suface-treating of steel sheet comprising light to heat conversion material, the steel sheet using the same and the surface treatment method using the same - Google Patents

Abstract

The present invention relates to a composition for surface treatment of a steel sheet containing a photothermal conversion material, a steel sheet using the same and a method for surface treatment of a steel sheet accordingly.
The composition for surface treatment of a steel sheet according to the present invention contains the photothermal conversion material dispersed in a composite resin made of a urethane resin and an acrylic resin, thereby having the effect of radiating heat by itself at low temperature. Accordingly, there is an effect of producing a steel sheet having a surface treatment layer having excellent corrosion resistance, resin adhesion, processability and electrical conductivity.

Description

Composition for suface-treating of steel sheet comprising light to heat conversion material, the steel sheet using the same and the surface treatment method using the same}

The present invention relates to a composition for surface treatment of a steel sheet containing a photothermal conversion material, a steel sheet using the same and a method for surface treatment of a steel sheet accordingly.

In general, when the resin is directly coated on the steel sheet, the corrosion resistance resin adhesion decreases due to the lowering of the affinity between the steel sheet and the resin layer, so that the treatment of the pretreatment layer is required 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 the application of the chromium-free pretreatment layer according to the current environmental regulations.

Heavy metals such as chromium, lead, mercury, and cadmium are harmful to the human body, and heavy metals in automobiles and households are regulated mainly in the EU and Japan. Hexavalent chromium is harmful to humans. Known as a substance. Therefore, there is a need for an environmentally friendly resin coated steel sheet that does not contain these harmful heavy metals.

On the other hand, the pre-treatment solution for pre-shielded steel sheet currently developed in Europe, etc. is a low-temperature no-rinse (peak metal temperature) of 80 ℃ PMT, but most acidic solution is composed of two-component type due to chemical instability, It is mixed and used in all production lines.

In addition, the Republic of Korea Application No. 10-2006-0136776 of the present invention is a composition for surface treatment of a steel sheet containing an acrylic resin, urethane resin, bentonite-based nanoclay powder, melamine-based curing agent, silicate, organic Ti or Zr oxide, It discloses about the composition for surface treatment of the steel plate which can be baked at the temperature of 160 degrees C or less.

However, the patent has a problem that when the dry coating thickness is more than 1.5㎛ loss of electrical conductivity and it is difficult to ensure high corrosion resistance when the composition is coated on a steel sheet alone.

In addition, when the steel sheet coated with the resin in the wet state passes through a radiation heating curing apparatus such as near infrared (NIR) or infrared (IR) light source, such as near infrared or infrared light is reflected on the surface of the steel sheet or the resin layer. There is a problem in that optical energy is lost (see FIG. 1).

Therefore, in order to apply sufficient heat, it is necessary to slow down the passing speed of the strip or apply a large amount of light in the curing process, but in this case, production efficiency is reduced by production time and energy loss.

On the other hand, when the heating time is not enough or the amount of light to be injected is insufficient, the corrosion resistance of the steel sheet is deteriorated due to the uncured film and the film adhesion problem occurs.

Therefore, in order to solve this problem, high corrosion resistance can be ensured even when the dry coating film is more than a predetermined thickness, and a pretreatment solution that can increase production efficiency by preventing energy loss during low temperature quench type surface treatment curing process is required. .

Korea Patent Registration No. 10-0887094

In order to solve this problem,

An object of the present invention is to provide a composition for surface treatment of a steel sheet comprising a photothermal conversion material, a steel sheet using the same, and a method for surface treatment of the steel sheet accordingly.

Another object of the present invention is to ensure a high corrosion resistance even when the dry coating film is more than a predetermined thickness, and to prevent the loss of energy during the low temperature baking treatment surface treatment process of a steel sheet comprising a photothermal conversion material that can increase the production efficiency The present invention provides a composition for surface treatment, a steel sheet using the same, and a method for surface treatment of a steel sheet.

In order to achieve the above object,

The invention in one embodiment,

Composite resin containing urethane resin and acrylic resin; And

It includes a photothermal conversion material dispersed in the composite resin,

The composite resin is a resin mixture in which a urethane resin and an acrylic resin are mixed in a weight ratio of 1: 100 to 100: 1,

The photothermal conversion material provides a composition for surface treatment of a steel sheet including a water dispersible polymer and a metal oxide.

Further, in another embodiment of the present invention,

Provided is a steel sheet comprising a dry coating film of the composition for surface treatment of the steel sheet.

Further, in another embodiment of the present invention,

Applying the composition for surface treatment of the steel sheet to the steel sheet so as to have a dry coating thickness of 0.05 to 2.5 μm; And

It provides a method for surface treatment of the steel sheet comprising the step of baking the steel sheet coated with the composition at 60 to 140 ℃ and cooling.

The composition for surface treatment of a steel sheet according to the present invention contains the photothermal conversion material dispersed in a composite resin made of a urethane resin and an acrylic resin, thereby having the effect of radiating heat by itself at low temperature.

In particular, the composition for surface treatment of the steel sheet according to the present invention can be used as an anticorrosive treatment by coating on the steel sheet, it is possible to low-temperature baking can reduce the process cost.

Thereby, the steel plate which has the surface treatment layer which has the outstanding corrosion resistance, resin adhesiveness, workability, and electrical conductivity can be manufactured.

1 is a schematic diagram showing a curing process of a conventional organic coated steel sheet.
Figure 2 is a schematic diagram showing the curing process of the organic coated steel sheet according to an embodiment of the present invention.

As the invention allows for various changes and numerous embodiments, particular embodiments will be illustrated in the drawings and described in detail in the written description.

However, this is not intended to limit the present invention to specific embodiments, it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

In the present invention, the terms "comprise" or "have" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, components, or a combination thereof.

In addition, it is to be understood that the accompanying drawings in the present invention are shown to be enlarged or reduced for convenience of description.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings, and the same or corresponding components will be given the same reference numerals regardless of the reference numerals, and redundant description thereof will be omitted.

The present invention provides a composition for surface treatment of a steel sheet containing a photothermal conversion material, a steel sheet using the same, and a method for surface treatment of a steel sheet accordingly.

1 is a schematic diagram showing a curing process of a conventional organic coated steel sheet.

Conventionally, when the dry coating thickness is 1.5 µm or more, there is a problem in that it is difficult to secure high corrosion resistance when coating the steel sheet with the composition alone. In addition, referring to the curing process of the organic coated steel sheet with reference to Figure 1, when the steel sheet coated with a wet resin is passed through a radiation heating type curing facility, such as near infrared (NIR) or infrared (IR), the near infrared or The light source 300, such as infrared rays, is reflected on the surface of the steel sheet 110 or the resin layer 120, so that light energy is lost.

In order to overcome this problem, the present invention provides a composition for surface treatment of a steel sheet comprising a photothermal conversion material according to the present invention, a steel sheet using the same and a method for surface treatment of the steel sheet accordingly.

Figure 2 is a schematic diagram showing the curing process of the organic coated steel sheet according to an embodiment of the present invention.

Referring to FIG. 2, the surface treatment composition forming the resin layer 120 of the steel sheet 110 including the photothermal conversion material 200 according to the present invention is photothermal conversion dispersed in a composite resin made of a urethane resin and an acrylic resin. By containing the material 200, specifically, the water dispersible polymer 210 and the metal oxide 220, the photothermal conversion material 200 itself can radiate heat at low temperature.

In particular, when passing through a radiation heating curing facility such as near infrared (NIR) or infrared (IR), the light source 300 such as the near infrared or infrared light is reflected on the surface of the steel sheet 110 or the resin layer 120 The problem that light energy is lost can be prevented.

Accordingly, there is an effect that the low-temperature baking can reduce the process cost, there is an advantage that can produce a steel sheet having a surface treatment layer having excellent corrosion resistance, resin adhesion, processability and electrical conductivity.

In the present invention, the "photothermal conversion material" means a material having a photothermal characteristic, that is, a property of generating heat according to light absorption, and may be configured in a form dispersed in a composite resin.

In particular, the photo-thermal conversion material is dispersed in the composite resin, it can absorb the light source during the infrared or near-infrared curing to radiate heat, thereby increasing the absorption rate of the radiant heat in the resin film.

In the present invention, the "composition for surface treatment of steel sheet" may be a composition constituting a resin layer constituting the upper layer portion of the steel sheet, for example, a composition of the pretreatment layer constituting the upper layer portion of the steel sheet, constituting the lower layer of the resin coating layer. can do.

On the other hand, the physical properties of the resin coated steel sheet are largely affected by the pretreatment layer and the resin layer. The pretreatment layer coating constituting the lower layer of the resin coated steel sheet has a shielding effect against corrosion factors, thereby ensuring corrosion resistance of the resin coated steel sheet, and improving corrosion resistance due to the effect of securing adhesion between the steel sheet and the upper resin layer. Since it serves to prevent the film of the resin layer, if the pretreatment layer does not secure these required characteristics, physical properties such as intended corrosion resistance and workability in the resin coated steel sheet are not achieved. In addition, the resin layer in the upper part of the steel plate has a primary shielding effect against corrosion factors and a shielding effect to prevent sudden elution or loss of the lower pretreatment layer to secure corrosion resistance of the resin coated steel sheet, and to obtain required quality and color of the steel sheet. Play a role.

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

The invention in one embodiment,

Composite resin containing urethane resin and acrylic resin; And

It includes a photothermal conversion material dispersed in the composite resin,

The composite resin is a resin mixture in which a urethane resin and an acrylic resin are mixed in a weight ratio of 1: 100 to 100: 1,

The photothermal conversion material provides a composition for surface treatment of a steel sheet including a water dispersible polymer and a metal oxide.

The term "parts by weight" used in the present invention means a weight ratio.

In one embodiment, the composite resin is a composite resin comprising a water-dispersible urethane-based resin and a water-dispersible acrylic resin, the urethane resin and the acrylic resin may be 1: 100 to 100: 1 by weight, 1:75 To 75: 1, 1:50 to 50: 1, 1:25 to 25: 1, 1:10 to 10: 1, 1: 5 to 5: 1 or 1: 2 to 2: 1. When the amount is added in an amount exceeding the above range, the resistance to external corrosion factors or chemicals is lowered and the corrosion resistance tends to be lowered. When the urethane resin is added in an amount exceeding the above range, the curing temperature is 140 ° C. It can be difficult to lower it below.

In addition, a resin having a number average molecular weight of 20,000 to 50,000 may be used as the acrylic resin. When the number average molecular weight of the acrylic resin is less than 20,000, it reacts with titanate or the like rather than reacting with the melamine resin, which is a curing agent, causing the resin to settle, or the coating film becomes too dense, and easily peeled off, and the number average molecular weight is 50,000 or more As the viscosity rises, it is difficult to form a uniform film, and the drying temperature rises, which lowers workability during production, increases the cleaning cost of the production equipment, and may be difficult to cure at a temperature below 140 ° C.

In addition, the acrylic resin may be made of a kind of monomer selected from the group consisting of n-butyl acrylate, methyl methacrylate, and ethylene acrylate monomers.

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

In addition, the composite resin including the urethane-based resin and the acrylic resin described above is characterized in that it comprises a light-to-heat conversion material that can radiate heat itself at low temperature.

In the present invention, "photothermal conversion resin" means a material having a property of generating heat in accordance with light absorption, it is characterized in that it is configured in a form dispersed in a composite resin.

More specifically, the photothermal conversion material may include a water dispersible polymer and a metal oxide, and the content of the photothermal conversion material may be in a range of 0.5 to 10 parts by weight based on 100 parts by weight of the composite resin.

In another embodiment, the content of the photothermal conversion material may be 0.5 to 7 parts by weight, 0.5 to 5 parts by weight, 1 to 4 or 1 to 2.5 with respect to 100 parts by weight of the composite resin. Here, when the light-heat conversion material is less than the above range, the amount of light-heat conversion material dispersed in the composite resin is too small, it may not exhibit the light-heat effect, if it exceeds the above range, the light-heat conversion material contained in the composite resin It is difficult to easily disperse it in the resin because the amount is too large, and the price is increased, and there is no great effect such as further improving corrosion resistance.

In addition, the photo-thermal conversion material of the present invention is composed of a water dispersible polymer and a metal oxide, the ratio of the water dispersible polymer and the metal oxide is in the range of 1: 2 to 10: 1 weight ratio, 1: 2 to 8: 1 weight ratio, 1: 2 to 6: 1 weight ratio range, 1: 2 to 4: 1 weight ratio range, 1: 2 to 2: 1 weight ratio range, or 1.5: 1 to 1: 1.5. On the other hand, when the water-dispersible polymer is less than the above range, the ratio of the metal oxide is relatively high compared to the water-dispersible polymer may cause a problem of poor dispersibility, if the water-dispersible polymer exceeds the above range, the ratio of the metal oxide This lowers the problem may be difficult to implement the excellent photo-thermal conversion effect of the metal oxide.

In addition, when the ratio of the metal oxide is less than the above range, as described above, the ratio of the metal oxide is lower than the water-dispersible polymer may be difficult to implement the excellent photo-thermal conversion effect of the metal oxide, the ratio of the metal oxide is in the above range When exceeding, the problem that the dispersibility falls in a composite resin may arise.

The ratio of the water-dispersible polymer and the metal oxide is to be easily dispersed in the composite resin to exhibit an excellent photothermal effect, as long as these conditions are satisfied, any ratio may be used.

1 is a schematic diagram showing a curing process of a conventional organic coated steel sheet, Figure 2 is a schematic diagram showing a curing process of an organic coated steel sheet according to the present invention.

Compared with FIG. 1, when the steel sheet is surface treated with the surface treatment composition according to the present invention, when irradiated with infrared rays or near infrared rays than the water-dispersible polymer alone, it absorbs more light than in the prior art. It can be converted into heat, and thus radiant heat in the resin layer can be obtained during the surface treatment of the steel sheet.

In addition, the photothermal conversion material according to the present invention is a water dispersible polymer and a metal oxide, and specifically, may be a thiophene polymer and a particulate metal oxide.

More specifically, thiophene-based polymers include poly (3,4-ethylenedioxythiophene): polystyrenesulfonic acid (poly (3,4-ethylenedioxythiophene sulfonate, PEDOT: PSS) and polythiophene (PT), poly (3-hex) Silthiophene) (poly (3-hexylthiophene, P3HT) may be at least one polythiophene derivative selected from the group consisting of.

The water dispersible polymer may be a conductive polymer in addition to a thiophene polymer, and may be, for example, polypyrrol or polyaniline.

However, for easy absorption, thiophene-based polymers are preferably used. For example, poly (3,4-ethylenedioxythiophene): polystyrene sulfone may be used.

In addition, the particulate metal oxide may be at least one selected from the group consisting of tungsten oxide (WO ₃ ), molybdenum mockside (MoO ₃ ) and vanadium oxide (V ₂ O ₅ ), for example, tungsten oxide (WO ₃ ) yl Can be.

In the composition of the present invention, the average particle diameter of the particulate metal oxide is not particularly limited, but may be preferably 5 μm or less and 3 μm or less. When the average particle diameter of the metal oxide exceeds 5 μm, solution stability may be lowered by rapid precipitation of the metal oxide, and the physical properties of the surface treatment composition may be deteriorated. The lower limit of the average particle diameter of the metal oxide is not particularly limited, but may preferably be 0.02 μm or more and 0.1 μm or more.

In addition, the present invention in one embodiment,

1.0 to 25.0 parts by weight of the composite resin;

0.1 to 5.0 parts by weight of a curing agent;

0.1 to 5.0 parts by weight of at least one organo-metal oxide selected from the group consisting of organic titanate and organic zirconate;

1.0 to 25 parts by weight of silicate; And

0.1 to 5 parts by weight of a triazole compound;

It provides a composition for surface treatment of a steel sheet comprising a.

In the composition for surface treatment of a steel sheet according to the present invention, when the content of the composite resin is less than 1 part by weight, there is a tendency that the binder does not sufficiently exhibit the role of connecting various additives to the composition, and exceeds 25 parts by weight. In the case of a large increase in the degree of composition of the composition may be difficult to control the adhesion amount. These resins have a hydrophilic group such as hydroxyl (-OH) constituting the coating film is advantageous when painting the resin layer on the top and serves as a binder that combines other additives. In order to ensure smooth workability, the resin may be dispersed in water or alcohol at 10 to 40% by weight rather than being used alone.

In addition, the curing agent may be used as a curing agent for the acrylic resin or urethane resin, melamine resin or formaldehyde resin. As the preferred melamine resin, in particular, an alkylated melamine curing agent may be used. For example, a methylated melamine curing agent or a butylated melamine curing agent substituted with a methyl group may be used.

The melamine resin is added in an amount of 0.1 to 5.0 parts by weight based on the composition for surface treatment of the steel sheet. If the content of the curing agent is less than 0.1 parts by weight, the curing reaction of the coating film is not sufficient to secure the desired physical properties. If the content of the curing agent is more than 5.0 parts by weight, there is no effect of increasing the curing reaction by additional addition. There exists a possibility of reducing the solution stability and the physical property of a resin film.

In particular, the curing agent is preferably added in an amount of 10 to 20 parts by weight per 100 parts by weight of the composite resin.

The composition for surface treatment of the steel sheet also has a minimum selected from the group consisting of colloidal silica and metal silicate compounds having a pH of 7.0 or higher, preferably pH 7.0-10.0, in order to improve the corrosion resistance of the pretreatment layer and the adhesion with the resin steel sheet. One or more silicate mixtures may be added in an amount of 1.0 to 25.0 parts by weight based on the composition for surface treatment of the steel sheet.

The metal silicate is preferably Li or Na, and the prepared resin is weakly alkaline at pH 8, and thus solution gelation 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 is used. It is preferable to use because it is stable without sedimentation occurring.

When the amount of the silicate mixture added is less than 1.0 part by weight, the effect of improving adhesion and corrosion resistance is reduced, and the effect of lowering the drying temperature is decreased. When the amount of the silicate mixture is greater than 25.0 parts by weight, the effect of improving the corrosion resistance and adhesion by silica addition is reduced. This is because it is difficult to produce a desired surface treatment layer for a resin coated steel sheet by burying in a roll surface or the like during the operation. It is preferable in view of dispersibility that these silicate mixtures use about 10-30 weight% in water or alcohol.

0.1 to 5.0 parts by weight of at least one organic-metal oxide selected from the group consisting of organic titanate and organic zirconate may be added to the composition for surface treatment of the steel sheet.

Preferred examples of the organotitanate include titanium diisopropoxide bis (acetylacetonate), titanium ortho ester, titanium (IV) butoxide, titanium (IV) (triethanol aminato) isopropoxide, titanium ( IV) 2-ethylhex oxide, titanium (IV) isopropoxide, and the like may be used. Preferred examples of the organic zirconate include tetrakis (triethanol aminato) zirconium (IV) and zirconium (IV) bis ( Diethyl citrato) -dipropoxide and the like can be used.

However, the organic titanate and organic zirconate are not limited thereto. The organo-metal oxide acts as a catalyst to improve the bonding strength of colloidal silica and contributes to the improvement of corrosion resistance and weldability by itself. The organo-metallic compound may not be expected to act as a silica bonding catalyst at less than 0.1 parts by weight, and even if it is added at an amount exceeding 5.0 parts by weight, there is no increase in the function of silica bonding catalyst. Therefore, there is no significant effect on improving corrosion resistance and solution gelation may occur. Rises significantly. These compounds can use about 40-60 weight% dispersed in water or alcohol.

On the other hand, the triazole compound may be used as a corrosion inhibitor in the surface treatment composition, and may include 0.1 to 5.0 parts by weight.

Although it does not specifically limit as a triazole compound, For example, 1,2,3-triazole, 1,2,4-triazole, 3-mercapto-1,2,4-triazole, 3-hydroxy -1,2,4-triazole, 3-methyl-1,2,4-triazole, 1-methyl- 1,2,4-triazole, 1-methyl-3-mercapto-1,2,4 One or more selected from the group consisting of -triazole, 4-methyl-1,2,3-triazole, benzotriazole and 1-hydroxybenzotriazole can be used, preferably 1,2,3- Selected from the group consisting of triazoles, 1,2,4-triazoles, 3-mercapto-1,2,4-triazoles, 3-hydroxy-1,2,4-triazoles and benzotriazoles One or more kinds may be used, and more preferably 1,2,3-triazole, 1,2,4-triazole or a mixture thereof may be used.

And optionally, at least one dispersant selected from the group consisting of polyether-modified polydimethylsiloxane and hydroxide carboxylic acid ester, or solution, in order to improve the wetting of the surface treatment composition of the steel sheet. Alternatively, a siloxane antifoaming agent including, for example, polyoxyethylenated siloxane, dimethylsiloxane, amino modified siloxane, epoxy modified siloxane, and the like may be optionally added to remove bubbles formed by stirring in a coater pan.

These additives may be at least one or more selected from the group consisting of a dispersant and an antifoaming agent, and may be added at 0.1 to 3.0 parts by weight based on the total solution, respectively.

When the dispersant or the antifoaming agent is 0.1 parts by weight or less, the dispersing effect of the solution is inadequate, the wettability and the defoaming effect are insufficient, and the bubble is easily transferred to the roll or the like during the operation, and the unpainted surface of the steel sheet is likely to occur. If excessively added, the wettability of the solution is excessively increased, so that it is difficult to control the adhesion amount during coating of the pretreatment solution, and the solution stability due to the excessive antifoaming agent is lowered.

On the other hand, when the composition for the surface treatment of the steel sheet based on weight%,

1.0 to 25.0 wt% composite resin;

0.1-2.5% by weight of photothermal conversion material;

0.1 to 5.0 weight percent of hardener;

0.1 to 5.0 wt% of at least one organo-metal oxide selected from the group consisting of organic titanate and organic zirconate;

Silicate 1.0-25%;

0.1 to 5.0 weight percent of a triazole compound; And

Solvent; may include.

Here, the solvent may be added 1 to 20% by weight of water or alcohol based on dispersion and quick-drying with respect to water as the main solvent. The alcohol causes the solvent to dry quickly and solvents with the water to aid dispersion. When the alcohol is added to the water less than 1% by weight, the effect of improving dispersibility is insignificant, and when more than 20% by weight of alcohol is added, the solid content of the solution rapidly increases due to evaporation of the alcohol, thereby decreasing the coating workability. The evaporation rate of the solvent is increased, which may adversely affect the formation of craters in the coating film.

The alcohol may be used by mixing one or more alcohols selected from the group prepared with ethanol, isopropanol, and butyl alcohol.

On the other hand, the steel sheet according to the present invention

Provided is a steel sheet comprising a dry coating film of the composition for surface treatment of the steel sheet.

At this time, the thickness of the dry coating film may be an average of 0.05 to 2.5㎛.

In particular, in the above-described composition for surface treatment of steel sheet, the water-dispersible polymer and the metal oxide, which are light-heat conversion materials, are dispersed in the composite resin, and the dry coating film is thicker than the conventional one because the light-heat conversion material itself can radiate heat at low temperature. It may also have excellent corrosion resistance, processability and resin adhesion.

In addition, the surface treatment method of the steel sheet according to the present invention

Applying the composition for surface treatment of the steel sheet to the steel sheet so as to have a dry coating thickness of 0.05 to 2.5 μm; And

It provides a method for surface treatment of the steel sheet comprising the step of baking the steel sheet coated with the composition at 60 to 140 ℃ and cooling.

At this time, the plated steel sheet, such as silicon, copper, magnesium, iron, manganese, titanium, zinc or a mixture of aluminum alloy plate, cold rolled steel sheet, galvanized steel sheet, zinc-based electroplating steel sheet, hot dip galvanized steel sheet, aluminum plating Steel sheet, galvanized steel plate coated with phosphate, as a dissimilar metal or impurity, for example, cobalt, molybdenum, tungsten, nickel, titanium, aluminum, manganese, iron, magnesium, tin, copper or a mixture thereof Steel sheet, hot rolled steel sheet, etc. may be used. Various methods such as electroplating, hot-dip plating, and vacuum deposition may be used as a method of plating zinc alloys containing zinc on a steel sheet or zinc and other metals such as iron, nickel, and cobalt.

On the other hand, the thickness of the dry coating film may be from 0.05 to 2.5 ㎛, when less than 0.05 ㎛ corrosion resistance, resin adhesion, etc. are lowered, if it exceeds 2.5 ㎛ may reduce the weldability and increase the production cost.

In another embodiment, it may have a dry coating film of 0.1 to 2.5 μm, 0.5 to 2.3 μm, 1 to 2.2 μm, 1.5 to 2.0 μm or 2.1 to 2.5 μm.

In addition, the baking temperature may be 60 to 140 ℃, when baking at a temperature of less than 60 ℃ insufficient drying, there is a risk of being washed away by water in the cooling process or transferred to the roll surface and lost, exceeding 140 ℃ In the case of baking at a temperature that does not have a large effect on the curing reaction, an increase in production cost may occur.

For example, the baking temperature may be 90 to 130 ℃.

The composition for surface treatment of the steel sheet of the present invention can be used to prepare a pretreatment layer for a preshielded steel sheet composed of an organic-inorganic composite component, and the pretreatment layer prepared by the surface treatment composition of the present invention has a corrosion resistance and resin adhesion of the resin component. It can improve and have a drying temperature reduction effect.

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

However, the following Examples and Experimental Examples are only illustrative of the present invention, and the content of the present invention is not limited to the following Examples and Experimental Examples.

<Example>

Example 1

(1) Preparation of Resin Composition for Surface Treatment

10 parts by weight of urethane resin, 10 parts by weight of acrylic resin, 0.25 parts by weight of photothermal conversion material, 10 parts by weight of colloidal silica (Snowtex-40 from Nissan Chemical), 10 parts by weight of alkylated melamine curing agent (Cytec 303 from Cytec), organic A resin composition for surface treatment was prepared by mixing 5 parts by weight of titanate (Tyzor TE® 5 manufactured by Dupont), 5 parts by weight of benzotriazole dispersed in water, and 0.5 parts by weight of siloxane-based dispersant (Ciba EFKA 3580).

In this case, the photothermal conversion material was prepared by mixing PEDOT: PSS [poly (3,4-ethylenedioxythiophene) polystyrene sulfonate) and tungsten oxide (WO ₃ ) in a 1.5: 1 weight ratio.

Solid content concentration of the surface treatment composition was set to about 15% by weight. For reference, water was used as the main ingredient except the solids, and the composition of Example 1 was prepared by adding 5% by weight of ethanol relative to water as an alcohol solvent.

(2) Coating of resin composition for surface treatment on material steel sheet

The above-mentioned resin composition for surface treatment was applied to a hot dip galvanized steel sheet (steel plate thickness: 0.6 mm) manufactured with a coating weight of 120 m ² / m using a bar coater to have a dry film thickness of 1 μm. And coated.

(3) Formation of Surface Treatment Layer

The steel sheet coated with the composition was passed through an infrared heating furnace. Specifically, the resin composition for surface treatment coated on the hot dip galvanized steel sheet was baked at a temperature of baking temperature of 90 ° C., followed by air cooling to have a thickness of 1 μm. A surface treatment layer was formed. This completed the surface-treated steel plate in which the surface treatment layer was formed.

Example 2

A surface-treated steel sheet was completed in the same manner as in Example 1 except that the baking temperature was changed to 110 ° C.

Example 3

A surface-treated steel sheet was completed in the same manner as in Example 1 except that the baking temperature was changed to 130 ° C.

Example 4-6

Except for changing the content and baking temperature of PEDOT: PSS and WO3 as shown in Table 1 was carried out in the same manner as in Example 1 to complete the surface-treated steel sheet.

acryl
(Parts by weight) urethane
(Parts by weight) PEDOT: PSS
(Parts by weight) WO ₃
(Parts by weight) Heating temperature (℃) Example 1 10 10 0.15 0.1 90 Example 2 10 10 0.15 0.1 110 Example 3 10 10 0.15 0.1 130 Example 4 10 10 0.5 0.5 90 Example 5 10 10 0.5 0.5 110 Example 6 10 10 0.5 0.5 130

Comparative Example

Comparative Examples 1 to 9

The surface-treated steel sheet was completed in the same manner as in Example 1 except that the components, the content and the baking temperature of the photothermal conversion material were changed as shown in Table 2 below.

acryl
(Parts by weight) urethane
(Parts by weight) PEDOT: PSS
(Parts by weight) WO ₃
(Parts by weight) Heating temperature (℃) Comparative Example 1-1 10 10 0 0 90 Comparative Example 1-2 10 10 0 0 110 Comparative Example 1-3 10 10 0 0 130 Comparative Example 2-1 10 10 0.15 0 90 Comparative Example 2-2 10 10 0.15 0 110 Comparative Example 2-3 10 10 0.15 0 130 Comparative Example 3-1 10 10 0.3 0 90 Comparative Example 3-2 10 10 0.3 0 110 Comparative Example 3-3 10 10 0.3 0 130 Comparative Example 4-1 10 10 0.5 0 90 Comparative Example 4-2 10 10 0.5 0 110 Comparative Example 4-3 10 10 0.5 0 130 Comparative Example 5-1 10 10 One 0 90 Comparative Example 5-2 10 10 One 0 110 Comparative Example 5-3 10 10 One 0 130 Comparative Example 6-1 10 10 0 0.1 90 Comparative Example 6-2 10 10 0 0.1 110 Comparative Example 6-3 10 10 0 0.1 130 Comparative Example 7-1 10 10 0 0.5 90 Comparative Example 7-2 10 10 0 0.5 110 Comparative Example 7-3 10 10 0 0.5 130 Comparative Example 8-1 10 10 0 One 90 Comparative Example 8-2 10 10 0 One 110 Comparative Example 8-3 10 10 0 One 130

Examples 7-15

(1) Preparation of Resin Composition for Surface Treatment

A resin composition for surface treatment was prepared in the same manner as in Example 1.

(2) Coating of resin composition for surface treatment on material steel sheet

Except having changed the thickness range of the surface treatment layer after drying as shown in Table 3 below, it carried out by the same method as Example 1 to coat the resin composition for surface treatment on the raw material steel sheet.

(3) surface treatment layer formation

Except for changing the curing temperature of the resin composition for surface treatment as shown in Table 3 below was carried out in the same manner as in Example 1 to complete a steel sheet on which a surface treatment layer was formed.

The thickness and the baking temperature of the surface treatment layer of the surface treatment steel sheets prepared in Examples 7 to 15 are collectively described in Table 3 below.

Thickness of Surface Treatment Layer (㎛) Baking temperature (℃) Example 7 1.0 90 Example 8 2.0 90 Example 9 2.5 90 Example 10 1.0 110 Example 11 2.0 110 Example 12 2.5 110 Example 13 1.0 130 Example 14 2.0 130 Example 15 2.5 130

Comparative Examples 9 to 17

(1) Preparation of Resin Composition for Surface Treatment

A resin composition for surface treatment was prepared in the same manner as in Comparative Example 5 (1 part by weight of PEDOT: PSS).

(2) Coating of resin composition for surface treatment on material steel sheet

Except having changed the thickness range of the surface treatment layer after drying as shown in following Table 4, it carried out by the same method as the comparative example 5, and coated the resin composition for surface treatment on the raw material steel plate.

(3) surface treatment layer formation

Except for changing the curing temperature of the resin composition for surface treatment as shown in Table 4 below was carried out in the same manner as in Comparative Example 5 to complete a steel sheet on which a surface treatment layer was formed.

The thickness and baking temperature of the surface-treated layer of the surface-treated steel sheets prepared in Comparative Examples 9 to 17 were collectively described in Table 4 below.

Thickness of Surface Treatment Layer (㎛) Baking temperature (℃) Comparative Example 9 1.0 90 Comparative Example 10 2.0 90 Comparative Example 11 2.5 90 Comparative Example 12 1.0 110 Comparative Example 13 2.0 110 Comparative Example 14 2.5 110 Comparative Example 15 1.0 130 Comparative Example 16 2.0 130 Comparative Example 17 2.5 130

Comparative Examples 18 to 26

(1) Preparation of Resin Composition for Surface Treatment

A resin composition for surface treatment was prepared in the same manner as in Comparative Example 9 (1 part by weight of WO ₃ ).

(2) Coating of resin composition for surface treatment on material steel sheet

Except having changed the thickness range of the surface treatment layer after drying as it described in Table 5, it carried out by the same method as the comparative example 8, and coated the resin composition for surface treatment on the raw material steel plate.

(3) surface treatment layer formation

Except for changing the curing temperature of the resin composition for surface treatment as shown in Table 5 below was carried out in the same manner as in Comparative Example 8 to complete a steel sheet on which a surface treatment layer was formed.

The thickness and the baking temperature of the surface treatment layer of the surface treatment steel sheets prepared in Comparative Examples 18 to 26 were collectively described in Table 5 below.

Thickness of Surface Treatment Layer (㎛) Baking temperature (℃) Comparative Example 18 1.0 90 Comparative Example 19 2.0 90 Comparative Example 20 2.5 90 Comparative Example 21 1.0 110 Comparative Example 22 2.0 110 Comparative Example 23 2.5 110 Comparative Example 24 1.0 130 Comparative Example 25 2.0 130 Comparative Example 26 2.5 130

Experimental Example

Experimental Example 1.

(1) corrosion resistance evaluation

In this experimental example, the change of the content of the photothermal conversion material and the physical properties according to the baking temperature were evaluated. Specifically, Experimental Example 1-6 Comparative Example 1-8 to evaluate the corrosion resistance for the composition.

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

◎: 120 hours or more of white rust

○: 96-119 hours of white rust outbreak

□: 72 ~ 95 hours

△: white rust occurrence 24-71 hours

Ⅹ: Within 24 hours

acryl
(Parts by weight) urethane
(Parts by weight) PEDOT: PSS
(Parts by weight) WO ₃
(Parts by weight) Baking temperature (℃) Corrosion resistance Comparative Example 1-1 10 10 0 0 90 □ Comparative Example 1-2 10 10 0 0 110 ○ Comparative Example 1-3 10 10 0 0 130 ◎ Comparative Example 2-1 10 10 0.15 0 90 ○ Comparative Example 2-2 10 10 0.15 0 110 ○ Comparative Example 2-3 10 10 0.15 0 130 ◎ Comparative Example 3-1 10 10 0.3 0 90 ◎ Comparative Example 3-2 10 10 0.3 0 110 ◎ Comparative Example 3-3 10 10 0.3 0 130 ◎ Comparative Example 4-1 10 10 0.5 0 90 ◎ Comparative Example 4-2 10 10 0.5 0 110 ◎ Comparative Example 4-3 10 10 0.5 0 130 ◎ Comparative Example 5-1 10 10 One 0 90 ○ Comparative Example 5-2 10 10 One 0 110 ○ Comparative Example 5-3 10 10 One 0 130 ◎ Comparative Example 6-1 10 10 0 0.1 90 □ Comparative Example 6-2 10 10 0 0.1 110 ◎ Comparative Example 6-3 10 10 0 0.1 130 ◎ Comparative Example 7-1 10 10 0 0.5 90 □ Comparative Example 7-2 10 10 0 0.5 110 ◎ Comparative Example 7-3 10 10 0 0.5 130 ◎ Comparative Example 8-1 10 10 0 One 90 ◎ Comparative Example 8-2 10 10 0 One 110 ◎ Comparative Example 8-3 10 10 0 One 130 ◎ Example 1 10 10 0.15 0.1 90 ◎ Example 2 10 10 0.15 0.1 110 ◎ Example 3 10 10 0.15 0.1 130 ◎ Example 4 10 10 0.5 0.5 90 ◎ Example 5 10 10 0.5 0.5 110 ◎ Example 6 10 10 0.5 0.5 130 ◎

Table 4 is a table evaluating the corrosion resistance of the compositions of Examples 1-3 and Comparative Examples 1-11.

First, Comparative Example 1 does not include the photothermal conversion material, the corrosion resistance was excellent when the baking temperature is 130 ℃ (Comparative Example 1-1), it was confirmed that the white blue generation time was reduced when the baking temperature is lowered.

Comparative Example 2 included a small amount of water-dispersible polymer PEDOT: PSS as a light-to-heat conversion material. In addition, similarly to Comparative Example 1, only when the baking temperature is 130 ℃ excellent corrosion resistance, it was confirmed that when the baking temperature was lowered white blue generation time was reduced.

On the other hand, when a large amount (0.3-0.5 parts by weight) of PEDOT: PSS was added as in Comparative Examples 3 and 4, it was confirmed that all had excellent corrosion resistance. However, when PEDOT: PSS is 1 part by weight, as in Comparative Example 5, it can be confirmed that the corrosion resistance is lower than that of Comparative Examples 3 and 4 at baking temperatures of 110 ° C and 130 ° C.

PEDOT: PSS was not uniformly dispersed in the composition, it was determined that the corrosion resistance was lowered.

In addition, referring to Comparative Examples 6 and 7, when only the metal oxide (WO ₃ ) as a light-to-heat conversion material, the corrosion resistance was not bad, but when the baking temperature is 110 ℃ it was confirmed that the white blue occurrence time was reduced than 130 ℃ .

Next, Comparative Example 8 and Examples 1 to 6 can confirm that the corrosion resistance is excellent.

However, Examples 1 to 3 contain a small amount of PEDOT: PSS and WO ₃ compared to Comparative Example 8.

On the other hand, it can be seen that Examples 1 to 3 and 4 to 6 all have excellent corrosion resistance, but Examples 1 to 3 contain smaller amounts of PEDOT: PSS and WO ₃ than Examples 4 to 6. have.

From these results, when the resin composition for surface treatment contains both a small amount of water dispersible polymer and a metal oxide, it is possible to form a surface treatment layer having excellent baking resistance even at a low baking temperature (90 to 130 ° C.), particularly at 90 ° C. Able to know.

Experimental Example 2

(1) Resin Adhesion Measurement

The thickness of the dry film was 2.5 ~ 4.5㎛ thick using a bar coater using a pre-shielded resin solution (Bumwoo Chemical POS-sealed product, hereinafter referred to as 'pre-shielded resin') on the pretreatment layer prepared to evaluate resin adhesion. After the coating, the water-cooled and dried specimens were baked at 150 to 280 ° C., and collected in a size of 30 mm × 50 mm, and then 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 peeling on the tape surface

□: Peeling within 5% of area of tape

△: peeling of 5% or more of the area of the tape surface

Χ: front surface peeling on the tape surface

(2) Machinability Measurement

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

◎: No peeling on the tape surface

□: Peeling within 5% of area of tape

△: peeling of 5% or more of the area of the tape surface

Χ: front surface peeling on the tape surface

(3) electrical conductivity measurement

The surface resistance of the steel sheets prepared in Examples and Comparative Examples was measured using a surface resistance meter (Loresta GP, manufactured by Mitsubishi Chemical Co., Ltd.), and the surface electrical conductivity was evaluated according to the following evaluation criteria.

(Double-circle): When the surface resistance of a surface-treated steel plate is 0.1 m (ohm) or less

□: Surface resistance of surface treated steel sheet is more than 0.1 mΩ and less than 1.0 mΩ

Χ: surface resistance of surface treated steel sheet exceeds 1.0 mΩ

Thickness of Surface Treatment Layer (㎛) Baking temperature (℃) Quality evaluation Adhesion Machinability conductivity Example 7 1.0 90 ◎ ◎ ◎ Example 8 2.0 90 ◎ ◎ □ Example 9 2.5 90 ◎ ◎ X Example 10 1.0 110 ◎ ◎ ◎ Example 11 2.0 110 ◎ ◎ □ Example 12 2.5 110 ◎ ◎ X Example 13 1.0 130 ◎ ◎ □ Example 14 2.0 130 ◎ ◎ ◎ Example 15 2.5 130 ◎ ◎ X

Thickness of Surface Treatment Layer (㎛) Baking temperature (℃) Quality evaluation Adhesion Machinability conductivity Comparative Example 9 1.0 90 ◎ ◎ ◎ Comparative Example 10 2.0 90 ◎ ◎ X Comparative Example 11 2.5 90 ◎ ◎ X Comparative Example 12 1.0 110 ◎ ◎ ◎ Comparative Example 13 2.0 110 ◎ ◎ X Comparative Example 14 2.5 110 ◎ ◎ X Comparative Example 15 1.0 130 ◎ ◎ ◎ Comparative Example 16 2.0 130 ◎ ◎ X Comparative Example 17 2.5 130 ◎ ◎ X Comparative Example 18 1.0 90 ◎ ◎ ◎ Comparative Example 19 2.0 90 ◎ ◎ X Comparative Example 20 2.5 90 ◎ ◎ X Comparative Example 21 1.0 110 ◎ ◎ ◎ Comparative Example 22 2.0 110 ◎ ◎ X Comparative Example 23 2.5 110 ◎ ◎ X Comparative Example 24 1.0 130 ◎ ◎ ◎ Comparative Example 25 2.0 130 ◎ ◎ X Comparative Example 26 2.5 130 ◎ ◎ X

As shown in Tables 7 and 8, in Examples 7 to 15 according to the present invention, the coating film thickness and the baking temperature after drying of the surface-treated layer during the manufacturing of the surface-treated steel sheet were 1.0 to 2.5 µm and 90 to 130, respectively. Being in the temperature range of ℃, it was confirmed that the adhesion, processability and electrical conductivity is excellent.

On the other hand, in Comparative Examples 9 to 26 not according to the present invention, the adhesion and workability was excellent, but as the baking temperature is lowered from 130 ℃ to 90 ℃, the thickness of the surface treatment layer is thicker from 1.0 ㎛ to 2.5 ㎛ It was confirmed that the conductivity is poor.

Specifically, the resin composition for surface treatment according to the embodiment of the present invention is excellent in the surface treatment layer of 1.0 ㎛ to 2.5 ㎛ thickness and baking temperature of 90 to 130 ℃ when containing both a small amount of water dispersible polymer and metal oxide It was found to have adhesion, processability and electrical conductivity.

From these results, in the surface treatment composition of the present invention, WO _{3 which} is a metal oxide is dispersed in PEDOT: PSS, which is a water dispersible polymer, and thus the water dispersible polymer and the metal oxide have their own photothermal conversion efficiency. It can be seen that an excellent surface treated steel sheet can be produced by increasing the radiant heat absorption rate of.

110: steel sheet 120: resin layer
200: photothermal conversion material
210: water dispersible polymer 220: metal oxide
300: light source

Claims (11)

Composite resin containing urethane resin and acrylic resin; And
It includes a photothermal conversion material dispersed in the composite resin,
The composite resin is a resin mixture in which a urethane resin and an acrylic resin are mixed in a weight ratio of 1: 100 to 100: 1,
The photothermal conversion material includes a combination of a thiophene-based polymer and a metal oxide,
The metal oxide is at least one selected from the group consisting of tungsten oxide (WO ₃ ), molybdenum mockside (MoO ₃ ) and vanadium oxide (V ₂ O ₅ ),
The ratio of the thiophene-based polymer and the metal oxide is in the range of 1: 2 to 10: 1 weight ratio composition for surface treatment of the steel sheet. The method of claim 1,
The content of the light-to-heat conversion material is 0.5 to 10 parts by weight based on 100 parts by weight of the composite resin, the composition for surface treatment of a steel sheet.
delete The method of claim 1,
The thiophene-based polymer is poly (3,4-ethylenedioxythiophene): polystyrenesulfonic acid (poly (3,4-ethylenedioxythiophene sulfonate, PEDOT: PSS) and polythiophene (PT), poly (3-hexylthiophene) (Poly (3-hexylthiophene, P3HT) is a composition for surface treatment of a steel sheet, characterized in that at least one member selected from the group consisting of. delete The method of claim 1,
The average particle diameter of a metal oxide is 5 micrometers or less, The composition for surface treatment of the steel plate.
delete The method of claim 1,
1.0 to 25.0 parts by weight of the composite resin;
0.1 to 5.0 parts by weight of a curing agent;
0.1 to 5.0 parts by weight of at least one organo-metal oxide selected from the group consisting of organic titanate and organic zirconate;
1.0 to 25 parts by weight of silicate; And
0.1 to 5 parts by weight of a triazole compound; Composition for surface treatment of steel sheet comprising a.
A steel sheet comprising a dry coating film of the composition for surface treatment of a steel sheet according to claim 1. The method of claim 9,
The dry film thickness is an average of 0.05 to 2.5 ㎛ steel sheet.
Applying the composition for surface treatment of the steel sheet according to claim 1 to a steel sheet such that a dry coating thickness is 0.05 to 2.5 μm; And
And baking the steel sheet coated with the composition at 60 to 140 ° C., followed by cooling.

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