KR100910511B1 - Low Temperature Curable Cr-free Pretreatment Solution Containing Conductive Polymer for Organic Coated Steels, Method for Perparing Pretreatment layer using the Pretreatment Solution, Pretreatment layer prepared by the Method and Steel Sheet comprising the Pretreatment layer - Google Patents

Abstract

The present invention is capable of baking at temperatures up to 160 ° C. using a conductive polymer having excellent electrical conductivity and having a good corrosion resistance, resin adhesion, and solution stability. The pretreatment layer manufactured by the manufacturing method, and the resin coating steel plate containing this pretreatment layer, 1.0-20.0 weight% of the resin mixture which mixed urethane resin and acrylic resin in the weight ratio of 1: 3-3: 1, 0.1-10.0 weight of at least one organic-metal oxide selected from the group consisting of 0.5-20.0 parts by weight of a water-soluble conductive polymer, 0.1-10.0% by weight of an alkylated melamine curing agent, organic titanate and organic zirconate per 100 parts by weight of the resin mixture % selected from the group consisting of colloidal silica and metal silicate compounds with a pH of 7.0 to 10.0 1.0 to 25.0 wt% of one or more silicate mixtures, 0.05 to 5.0 wt% of at least one nanoclay selected from the group consisting of bentonite and montmonite and a solvent composition for surface treatment of a steel sheet, wherein The composition is applied to a steel sheet so as to have a dry coating thickness of 0.05 to 1.5 μm, and baked at 60 to 160 ° C., followed by air cooling or water cooling of the resin coated steel sheet pretreatment layer, the pretreatment layer prepared by the preparation method, and the pretreatment. A resin coated steel sheet comprising a layer is provided.

The solution composition is environmentally friendly and does not contain heavy metals such as chromium, which is harmful to the human body, and has excellent solution stability. Since the resin adhesiveness, weldability and workability are exhibited, it is suitable for use as a pretreatment layer for resin coated steel sheets for various applications such as pre-shielded steel sheets and fuel tank steel sheets.

Water Soluble Conductive Polymer, Chrome Free, Polypyrrole, Polyaniline, PEDOT, Urethane Resin, Acrylic Resin

Description

Low temperature curable chromium-free pretreatment solution composition for resin coated steel sheet containing conductive polymer, method for preparing pretreatment layer using the composition, steel sheet including pretreatment layer and pretreatment layer by the preparation method {Low Temperature Curable Cr-free Pretreatment Solution Containing Conductive Polymer for Organic Coated Steels, Method for Perparing Pretreatment layer using the Pretreatment Solution, Pretreatment layer prepared by the Method and Steel Sheet comprising the Pretreatment layer}

The present invention uses a conductive polymer having an effect of improving conductivity and corrosion resistance, and is a low-temperature small-type chromium-free pretreatment solution composition for a resin coated steel sheet to which a conductive polymer is added, a pretreatment layer manufacturing method using the composition, a pretreatment layer by the preparation method, and A steel sheet comprising the pretreatment layer, and in particular, at least one organic-metal selected from the group consisting of a water-soluble conductive polymer, a mixture of a urethane resin and an acrylic resin, an alkylated melamine curing agent, an organic titanate and an organic zirconate A resin solution composition for surface treatment of a steel sheet, a method for producing a pretreatment layer using the composition, comprising at least one silicate mixture and a solvent selected from the group consisting of oxides, colloidal silica, and metal silicate compounds. due to The present invention relates to a prepared pretreatment layer and a resin coated steel sheet including 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 at a temperature of about 80 ° C. or less is possible, 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 in steel materials requiring low-temperature baking such as BH steel sheets.

In addition, the composition of the present inventors Korean application No. 2006-136776 contains an acrylic resin and urethane resin, bentonite-based nanoclay powder, melamine-based curing agent, silicate, organic Ti or Zr oxide and at a temperature of 160 ℃ or less Although baking is possible, when the dry coating thickness is 1.5 μm or more, there is a problem in that electrical conductivity is lost and high corrosion resistance is difficult to secure when the composition is coated on a steel sheet alone.

Therefore, development of a pretreatment solution composition for resin coated steel sheets having high electrical conductivity is required as a means to solve these problems, and a pretreatment solution having improved corrosion resistance is also required by use alone.

Accordingly, an aspect of the present invention is to provide a solution composition for surface treatment of a steel sheet including a conductive polymer having excellent electrical conductivity and having excellent solution stability, corrosion resistance, and conductivity.

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

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

Another aspect of the invention to provide a resin coated steel sheet comprising the pretreatment layer.

According to one aspect of the invention, 1.0 to 20.0% by weight of a resin mixture of a urethane resin and acrylic resin in a weight ratio of 1: 3 to 3: 1, 0.5 to 20.0 parts by weight of a water-soluble conductive polymer per 100 parts by weight of the resin mixture, Consisting of colloidal silica and metal silicate compounds having from 0.1 to 10.0% by weight of alkylated melamine curing agent, from 0.1 to 10.0% by weight of at least one organo-metal oxide selected from the group consisting of organic titanates and organic zirconates, pH 7.0 to 10.0 1.0-25.0 wt% of at least one silicate mixture selected from the group, 0.05-5.0 wt% of at least one nanoclay selected from the group consisting of bentonite and montmonite and solvents for surface treatment of a steel sheet Solution compositions are provided.

According to another aspect of the present invention, there is provided a method for producing a resin coated steel sheet pretreatment layer in which a solution composition is applied to a steel sheet so as to have a dry coating thickness of 0.05 to 1.5 μm, baked at 60 to 160 ° C., and then air-cooled or water-cooled.

According to still another aspect of the present invention, a resin coated steel plate pretreatment layer prepared by applying the solution composition to a steel sheet so as to have a dry coating thickness of 0.05 to 1.5 μm, baking at 60 to 160 ° C., and then air-cooling or water-cooling is provided. do.

According to still another aspect of the present invention, a resin coating comprising a pretreatment layer prepared by applying the solution composition to a steel sheet so as to have a dry coating thickness of 0.05 to 1.5 μm, baking at 60 to 160 ° C., and then air-cooling or water-cooling. Steel sheet is provided.

The pretreatment coating film for resin coated steel sheets coated on alloy steel sheets, cold rolled steel sheets, plated steel sheets, hot rolled steel sheets, and the like by using a solution composition and a manufacturing method comprising a conductive polymer having excellent electrical conductivity of the present invention has excellent solution stability, corrosion resistance, and conductivity. It has a resin coating treatment on the upper part and shows excellent weldability, resin adhesiveness and workability. It is coated on a steel sheet and used as an anticorrosive treatment, or a phosphate coating or electrodeposition coating film such as a rear part of a car or a heme part. It is suitable for use in pre-treated layers of pre-shielded steel sheets and other resin-coated steel sheets to be used in areas where it is difficult to form.

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 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 formation of the layer, if the pretreatment layer does not secure such required characteristics, 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 layer pretreatment layer to secure corrosion resistance of the resin coated steel sheet and to impart the required quality or color of the steel sheet. It plays a role.

In order to have a structure in which the pretreatment layer has a favorable structure to secure adhesion, a water-dispersible acrylic resin and a urethane resin mixture are added to 1 to 20% by weight of the total surface treatment solution composition. Preferably, the acrylic resin and the urethane resin are in the range of 1: 3 to 3: 1 by weight, and when the acrylic resin is added in an amount exceeding the above range, the resistance to external corrosion factors or chemicals is lowered and thus the corrosion resistance is reduced. There exists a tendency for this to fall, and when urethane resin is added in the quantity exceeding the said range, it becomes difficult to lower hardening temperature to 160 degrees or less. When the resin mixture is less than 1% by weight of the total solution composition, it tends to not sufficiently serve as a binder for connecting various additives to the composition, and when it exceeds 20% by weight, the viscosity of the composition is greatly increased. It can be difficult to control the adhesion amount. These resins have a hydrophilic group such as a hydroxyl group (-OH) constituting the coating film is advantageous when painting the resin layer on the top and serves as a binder that binds other additives. 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.

As the acrylic resin, a resin having a number average molecular weight of 20,000 to 50,000 may be used. When the number average molecular weight of the acrylic resin is less than 20,000, it is more likely to settle the resin by reacting with titanate or the like rather than reacting with the melamine resin, which is a curing agent, or the coating film becomes too dense and easily peeled off, and the viscosity of the composition when the number average molecular weight is 50,000 or more It is difficult to form a uniform film due to the rise, the drying temperature is increased, the workability during production decreases, the cleaning cost of the production equipment increases, and it is difficult to cure at a temperature below 160 ℃. 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 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 addition, the addition of a water-soluble conductive polymer to the pretreatment layer lowers the potential difference while lowering the potential difference and slows the penetration rate of corrosion factors such as chlorine ions. Therefore, when the resin is applied on the pretreated film, the electrical conductivity and weldability of the resin coated steel sheet can be improved. Since the water-soluble conductive polymer is inferior in dispersibility to the solution composition, it is preferable to use a dispersion of 20 to 50 wt% in water or alcohol.

Water-soluble conductive polymers that may be added to the pretreatment layer include, but are not limited to, Polypyrrol, Polyaniline and PEDOT [(poly, 3,4-ethylenedioxythiophene)]. It is not limited. Polyaniline can be imparted with conductivity through protonated or oxidized doping, which can be conveniently synthesized in relatively high yields from relatively inexpensive monomers, and the conductive form has good chemical stability and high electrical conductivity. In addition to polyaniline, polypyrrole also has excellent thermal and atmospheric stability, easy electrical and chemical synthesis, and high electrical conductivity. PEDOT is a conductive polymer which is converted by electrochemical or chemical polymerization of a monomer of 3,4-ethylenedioxythiophene (EDOT) structure introduced by Bayer, Germany.

The water-soluble conductive polymer is preferably included in the solution composition for surface treatment of a steel sheet at 0.5 to 20.0 parts by weight per 100 parts by weight of the resin mixture, based on the amount of the resin mixture, the amount of the water-soluble conductive polymer is 100 If it is less than 0.5 parts by weight, it is not effective to improve the electrical conductivity and corrosion resistance, and if it exceeds 20.0 parts by weight, it is difficult to disperse uniformly in the resin composition, and the price will be increased, and the effect of further improving the electrical conductivity and corrosion resistance will be great. There is no.

Melamine resin or formaldehyde resin may be used as a curing agent for the acrylic or urethane 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 10.0% by weight based on the solution composition for surface treatment of the steel sheet. 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 is more than 10.0% 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 an amount of 10 to 20 parts by weight per 100 parts by weight of the resin mixture.

The solution composition for surface treatment of the steel sheet further includes at least 1 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. More than one silicate mixture is added in an amount of 1.0 to 25.0 wt% based on the solution 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. The amount of the added silicate mixture is less than 1.0% by weight, the effect of improving the adhesion and corrosion resistance is reduced and the effect of lowering the drying temperature is decreased, and when the amount of the silicate mixture exceeds 25.0% by weight, the effect of improving the corrosion resistance and adhesion by the addition of silica is reduced. This is because it is difficult to prepare a pretreatment layer for the desired resin coated steel sheet by burying in the roll surface or the like during the work. It is preferable in view of dispersibility that these silicate mixtures use about 10-30 weight% in water or alcohol.

At least one organic-metal oxide selected from the group consisting of organic titanate and organic zirconate may be added to the solution composition for surface treatment of the steel sheet in an amount of 0.1 to 10.0 wt% based on the solution 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-ethylhexoxide, 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 0.1 wt% or less, and even when added at 10.0 wt% or more, there is no increase in the action of the silica bonding catalyst. Therefore, there is no significant effect on improving corrosion resistance and solution gelation may occur. Greatly rises. It is preferable to use these compounds dispersed in water or alcohol at about 40 to 60% by weight.

As a solvent of the solution composition for surface treatment of the steel sheet, alcohol or water may be added in an amount of 1 to 20 wt% based on water as a main solvent for dispersion and quick drying. The alcohol causes the solution to dry quickly and acts as a solvent in the solution with 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 the alcohol is added in excess of 20% by weight, the solid content of the solution rapidly increases due to the evaporation of the alcohol, thereby improving the coating workability. It is lowered and the evaporation rate of the solvent is increased, which adversely affects the formation of craters in the coating film. The alcohol may be used by mixing at least one alcohol selected from the group consisting of ethanol, isopropanol and butyl alcohol.

Optionally, at least one water-dispersible nanoclay selected from the group consisting of bentonite and monteronite may be added to the solution composition for surface treatment of the steel sheet to improve corrosion resistance of the pretreatment layer. 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 used in the 0.05 ~ 5.0% by weight based on the solution composition for the surface treatment of the steel sheet, when the content of the nanoclay is used in less than 0.05% by weight due to the lack of shielding effect is not a large effect on improving the corrosion resistance 5.0% by weight When used above, the viscosity of the whole solution is greatly increased, the hardness of the pretreatment film is increased after baking, which causes the film to swell, and the film becomes uneven and incompletely coated spots are formed, and the adhesion to the upper resin is reduced to remove the film. Not desirable However, when the nanoclay itself is mixed with the solution, it is difficult to disperse, so 0.5-15 parts by weight of nanoclay per 100 parts by weight of a solvent selected from the group consisting of water, alcohol, and a mixture of water and alcohol is dispersed in water for effective dispersion. Can be. That is, if nanoclay is added directly into the solution, the nanoclay absorbs the liquid component, the viscosity may increase rapidly, and solution coagulation may occur. Thus, the solution is pre-dispersed in a solvent selected from the group consisting of water, alcohol, and a mixture of water and alcohol. It is preferable to add. The nanoclay is dispersed in the solvent alone, or 0.5 to 2.0 parts by weight of 2-amino-2-methyl-1-propanol per 100 parts by weight of the solvent, if the amount in terms of nanoclays 3.3 ~ compared to the content of nanoclays A solution peeled off with 400% 2-amino-2-methyl-1-propanol can be added. When 2-amino-2-methyl-1-propanol is less than 0.5 part by weight, it penetrates into the interlayer of nanoclay to separate the powder. The role of improving acidity cannot be expected, and when it exceeds 2.0 parts by weight, the improvement of dispersibility does not increase significantly. The 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 the nanoclay in water.

Also optionally, at least one dispersing agent selected from the group consisting of polyether-modified polydimethylsiloxane and hydroxide carboxylic acid ester, or agitation of a solution, in order to improve the wetting of the solution composition for surface treatment of the steel sheet To remove bubbles formed by stirring in a heavy or cotter pan, a siloxane antifoaming agent including, for example, polyoxyethylenated siloxane, dimethylsiloxane, amino modified siloxane, epoxy modified siloxane and the like can be optionally added. These additives may be at least one or more selected from the group consisting of a dispersant and an antifoaming agent, 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 that the bubbles are transferred to the roll or the like during operation and unpainted on the surface of the steel sheet, and more than 3.0 wt% When added, the wettability of the solution is excessively increased, so that 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.

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

The plated steel sheet to which the present invention can be applied may be silicon alloy, copper, magnesium, iron, manganese, titanium, zinc or an aluminum alloy plate added with a mixture thereof, cold rolled steel, galvanized steel, zinc-based electroplated steel, hot dip galvanized As a dissimilar metal or impurity, for example, cobalt, molybdenum, tungsten, nickel, titanium, aluminum, manganese, iron, magnesium, tin, copper, or mixtures thereof in steel sheets, aluminum-plated steel sheets, plating layers, Coated galvanized steel sheet, hot rolled steel sheet and the like can be used. Various methods, such as electroplating, hot-dip plating, and vacuum deposition, may be used to plate zinc alloys containing zinc on a steel sheet or zinc and other metals such as iron, nickel, and cobalt.

After applying the solution composition for surface treatment of the present invention to the plated steel sheet so that the thickness of the dry coating film is 0.05 ~ 1.5㎛, after baking to steel plate temperature of 60 ~ 160 ℃ and air-cooled or water-cooled. When the thickness of the dry coating film is less than 0.05 μm, corrosion resistance, resin adhesion, and the like are lowered. When it exceeds 1.5 μm, the weldability is reduced and the production cost is increased. In addition, when baking at a temperature of less than 60 ℃ inadequate drying may be washed away by water during the cooling process or transferred to the surface of the roll may be lost, when baking at a temperature exceeding 160 ℃ a great effect on the curing reaction No increase in production costs.

The total solid content of the solution composition for surface treatment of the steel sheet composed of the above components is preferably maintained at 5 to 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.

According to the present invention, a resin coated steel sheet pretreatment layer using the resin solution composition and the resin coated steel sheet pretreatment layer manufacturing method and a resin coated steel sheet including the same are provided.

By applying the resin composition of this invention on a steel plate, the pre-processed coating layer for resin coated steel sheets which is excellent in corrosion resistance, adhesiveness, and weldability is manufactured. More specifically, after applying the solution composition for surface treatment of the present invention to the steel sheet so that the thickness of the dry coating film is 0.05 ~ 1.5㎛, after baking at a steel sheet temperature of 60 ~ 160 ℃ and air-cooled or water-cooled to pretreatment layer of the resin-coated steel sheet And to prepare a resin coated steel sheet comprising the same. When the thickness of the dry coating film is less than 0.05 μm, corrosion resistance, resin adhesion, and the like are lowered. When it exceeds 1.5 μm, the weldability is reduced and the production cost is increased. In addition, when baking at a temperature of less than 60 ℃ is insufficient drying, there is a risk of being washed away by water in the cooling process, or transferred to the surface of the roll and lost, and when baked at temperatures exceeding 160 ℃, large curing reaction It is ineffective and rises in production costs.

The solution composition of the present invention is used to prepare a pretreatment layer for a pre-shielded 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. The corrosion resistance and adhesion are improved by silica, the corrosion resistance and solution stability are secured by the blocking effect of the nanoclay, and the organic Ti component improves the corrosion resistance and weldability, and the 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. In particular, the addition of a conductive polymer improves conductivity and corrosion resistance.

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 the present embodiment, the solution stability of the resin solution according to the content and curing agent content of polypyrrol, polyaniline (Polyaniline) and PEDOT [Poly (3,4-ethylenedioxythiophene)], acrylic resin, urethane resin The physical properties of the resin coating were evaluated.

At this time, the quality characteristics were evaluated by controlling the content of acrylic resin, urethane resin, curing agent and other additives. In the present Example 1, the content of urethane, acryl, and curing agent represents the weight% of the resin solid except water and alcohol, and the content of the conductive polymer is the weight part of the conductive polymer added per 100 parts by weight of resin (PHR, Parts per hundred). resin).

The urethane-based resin of the present invention prepared a urethane-based resin having a number average molecular weight of 70,000 consisting of isophorene diisocyanate, adipic acid, and a polyalcohol monomer as a urethane-based monomer. As the acrylic monomer, an acrylic resin having a number average molecular weight of 30,000 was prepared from n-butyl acrylate, methyl methacrylate, n-butyl methacrylate, and ethylene acrylate monomers. The water-soluble conductive polymer is Germany H.C. Bayck P from Starck, Cymel 303 from Cytec, USA was used, 10% by weight colloidal silica (Snowtex-40 from Nissan Chemical), 5% by weight organic titanate (Dupont Tyzor TE®). 0.1 wt% of bentonite-based nanoclay powder (Kunipia-F) and 0.5 wt% of siloxane-based dispersant (Ciba EFKA 3580) were added, respectively.The solid content concentration of the surface treatment composition was about 15 wt%. Water was used as the remaining main component, and 5 wt% of ethanol relative to water was added as an alcohol solvent to prepare solution compositions of Inventive Examples 1-13 and Comparative Examples 1-10. , Corrosion resistance, weldability, adhesiveness and workability after resin coating 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. ? When the precipitate did not occur and no gel was formed,? When the precipitate was formed at 2 vol% or more or?, And the case where the precipitate was at least 5 vol% and the gel was formed was represented by X.

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 corrosion state was measured by measuring the occurrence time of more than 5% of white blue and red blue depending on 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

×: White rust outbreak: 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 number of RBIs was evaluated as the number of consecutive RBIs and the evaluation criteria are as follows.

◎: More than 1,500 consecutive RBIs

○: 1,200 ~ 1,500 consecutive RBIs

□: 800 ~ 1,200 consecutive RBIs

△: 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, the water-cooled and dried specimens were baked at 150 to 280 ° C., and collected in a size of 30 mm X 50 mm, immersed in boiling water for 30 minutes, and dried, and then peeled off 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 the 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

×: All surfaces peeled off the tape surface

Table 1

division Resin composition (% by weight) Resin Content (wt%) Curing agent (% by weight) Conductive Polymer (PHR) Quality characteristic urethane acryl Solution stability Corrosion resistance Weldability Resin adhesion Machinability Comparative Example 1 100 0 One 5 0 ◎ △ ○ □ ◎ Comparative Example 2 80 20 5 10 0 ○ ○ △ □ Inventive Example 1 63 37 10 10 Polypyrrole 5 ◎ ◎ ◎ ◎ ◎ Inventive Example 2 60 40 10 10 Polyaniline 5 ◎ ◎ ◎ ◎ ◎ Inventive Example 3 56 44 10 10 PEDOT 5 ◎ ◎ ◎ ◎ ◎ Inventive Example 4 50 50 10 10 Polypyrrole 5 ◎ ◎ ◎ ◎ ◎ Inventive Example 5 50 50 15 10 Polyaniline 5 ◎ ◎ ◎ ◎ ◎ Inventive Example 6 44 56 15 10 PEDOT 5 ◎ ◎ ◎ ◎ ◎ Inventive Example 7 40 60 10 7 Polypyrrole 5 ◎ ◎ ◎ ◎ ◎ Inventive Example 8 35 65 15 10 Polyaniline 5 ◎ ◎ ◎ ◎ ◎ Inventive Example 9 30 70 15 10 PEDOT 5 ◎ ◎ ◎ ◎ ◎ Inventive Example 10 25 75 10 10 Polypyrrole 5 ◎ ◎ ◎ ◎ ◎ Comparative Example 3 3 97 30 10 Polyaniline 5 ○ △ ◎ ◎ x Comparative Example 4 0 100 5 10 Polyaniline 25 ○ △ ◎ □ x Inventive Example 11 43 57 10 5 PEDOT 5 ◎ ◎ ◎ ◎ ◎ Inventive Example 12 40 60 16 10 Polypyrrole 10 ◎ ◎ ◎ ◎ ◎ Comparative Example 5 50 50 30 30 0 x ○ ○ x ◎ Comparative Example 6 50 50 2 0 0 ◎ x x △ △ Comparative Example 7 50 50 One 3 0 x ◎ △ ◎ □ Inventive Example 13 57 43 15 8 Polyaniline 2 ◎ ◎ ◎ ◎ ◎ Comparative Example 8 80 20 30 2 0 ○ x △ ◎ □ Comparative Example 9 60 40 5 8 0 x △ ○ □ □ Comparative Example 10 55 45 5 8 0 ◎ △ ◎ x □

<Example 2>

10 wt% of a water-soluble conductive polymer (polypyrrole: ConQuest XP1000, Aldrich, ConQuest XP1000, polyaniline: ADS650WP, PEDOT: Baytron P, HC Starck, Germany) was added to the acrylic resin, urethane resin, and melamine curing agent shown in Inventive Example 1. Electrical conductivity was evaluated. Electrical conductivity was evaluated using Mitsubishi Chemical's Loresta GP.

TABLE 2

Conductive Polymer Type Electrical Conductivity (S / cm) Comparative Example 11 - 1.157X10 ⁵ Inventive Example 14 Polypyrrole 1.193X10 ⁵ Inventive Example 15 Polyaniline 1.230 X 10 ⁵ Inventive Example 16 PEDOT 1.230 X 10 ⁵

<Example 3>

In the present embodiment, the resin composition is formed on the base steel sheet, which is a zinc alloy plated or electroplated steel plate with a coating thickness 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 to evaluate the corrosion resistance, weldability, resin adhesion and workability.

TABLE 3

division Manufacture conditions Quality evaluation Baking temperature (℃) Coating thickness (μm) 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 ◎ ○ ○ ◎

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

Figure 2 compares the corrosion resistance characteristics of Inventive Examples 2 and 3 and Comparative Example 2 evaluated by the salt spray tester.

Claims (14)

1.0-20.0 wt% of a resin mixture obtained by mixing a urethane resin and an acrylic resin in a weight ratio of 1: 3 to 3: 1, 0.5-20.0 parts by weight of a water-soluble conductive polymer, 0.1-10.0 wt% of a curing agent, and organic per 100 parts by weight of the resin mixture. At least one silicate mixture selected from the group consisting of colloidal silica and metal silicate compounds having from 1 to 10.0% by weight of at least one organic-metal oxide selected from the group consisting of titanate and organic zirconate 1.0 ~ 25.0% by weight, 0.05 to 5.0% by weight of at least one nanoclay selected from the group consisting of bentonite-based and montmonite-based, and a solution composition for surface treatment of a steel sheet. The solution composition of claim 1, wherein the water-soluble conductive polymer is selected from the group consisting of polypyrrol, polyaniline, and PEDOT [Poly (3,4-ethylenedioxythiophene)]. The solution composition for surface treatment of a steel sheet according to claim 1, wherein the resin mixture, the silicate mixture, the organo-metal oxide or the water-soluble conductive polymer 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 in which 1 to 20% by weight of alcohol is added. The solution composition for surface treatment of a steel sheet according to claim 1, wherein the curing agent is an alkylated melamine curing agent or a formaldehyde resin. delete The method of claim 1, further comprising 0.5 to 2.0 parts by weight of 2-amino-2-methyl-1propanol per 100 parts by weight of a solvent selected from the group consisting of water, alcohol, and a mixture of water and alcohol together with the nanoclay. A solution composition for surface treatment of a steel sheet. The method according to claim 1, wherein at least one or more nanoclays selected from the group consisting of bentonite and montmonite, or the nanoclay to which 2-amino-2-methyl-1propanol is added is water, alcohol, or water and alcohol The solution composition for surface treatment of a steel sheet, which is added in a dispersed form in a mixture of the. The solution composition of claim 1, wherein the solution composition further comprises 0.1 to 3.0 wt% of at least one additive selected from the group consisting of a dispersant and an antifoaming agent. The solution composition for surface treatment of a steel sheet according to claim 9, wherein the dispersant is at least one selected from the group consisting of polyether-modified polydimethylsiloxane and hydroxide carboxylic acid ester, and the antifoaming agent is a siloxane antifoaming agent. . The method of claim 1, wherein the steel sheet is an aluminum alloy plate, a cold rolled steel sheet, a galvanized steel sheet, a zinc-based electroplating steel sheet, hot-dip galvanized, to which silicon, copper, magnesium, iron, manganese, titanium, zinc or a mixture thereof is added. Steel plate, aluminum plated steel plate, galvanized steel plate coated with phosphate A solution composition for surface treatment of a steel sheet, which is selected from the group consisting of a steel sheet and a hot rolled steel sheet. The solution composition of any one of claims 1 to 5 and 7 to 10 is applied to a steel sheet so as to have a dry coating thickness of 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. delete The solution composition of any one of claims 1 to 5 and 7 to 10 is applied to a steel sheet so as to have a dry coating thickness of 0.05 to 1.5 μm, and 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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