JP2007046143A - Chromium-free surface treated steel sheet having excellent performance balance - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface treated steel sheet having an excellent balance in fingerprint resistance, electric conductivity, coating adhesion, slidability (workability), heat resistance or the like in addition to corrosion resistance in a flat part, after alkali degreasing and in a worked part. <P>SOLUTION: Using an aqueous surface treatment liquid comprising: (A) a cationic polyurethane resin; (B) a cationic phenol resin; (C) a silane coupling agent; (D) a manganese compound; (E) a zirconium compound; (F) a vanadium compound; and a lubricant with a particle diameter of 0.1 to 0.5 μm in the following solid content mass ratios (D to F are contents expressed in terms of metals), a surface treatment film with a coating weight of 0.1 to 3 g/m<SP>2</SP>is formed on the surface of a galvanized steel sheet: A/B=7 to 120, C/(A+B)=0.2 to 0.75, D/(A+B)=0.005 to 0.025, E/(A+B)=0.01 to 0.075, F/(A+B)=0.001 to 0.025, and G/(A+B)=0.03 to 0.4. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a non-chromium surface-treated steel sheet using a zinc-based plated steel sheet as a base material. The surface-treated steel sheet of the present invention is excellent in corrosion resistance of the flat part, after alkaline degreasing and in the processed part, and also excellent in fingerprint resistance, conductivity, paint adhesion, workability (sliding property), and heat resistance. ing.

  Conventionally, zinc-based plated steel sheets including galvanized steel sheets and zinc alloy-plated steel sheets have been widely used for home appliances and building materials. Since the zinc-based plated steel sheet has insufficient corrosion resistance and paint adhesion as it is, products subjected to chemical conversion treatment such as chromate and zinc phosphate are manufactured. Among these products, chromate-treated products may be used without coating depending on the application. In that case, since fingerprints adhere to the surface of the steel sheet and the appearance is impaired, a product called an anti-fingerprint steel sheet coated with an organic resin has been put to practical use.

  This fingerprint-resistant steel sheet, that is, a surface-treated steel sheet obtained by subjecting a zinc-based plated steel sheet to chromate treatment and coating an organic resin on the formed chromate film, is flat surface corrosion resistance, corrosion resistance after alkaline degreasing, processed part corrosion resistance, Excellent balance of required characteristics such as fingerprint, electrical conductivity, paint adhesion, processability, heat resistance, etc., painted or unpainted for various uses of home appliances and building materials It can be used as it is.

However, with the recent regulation of hexavalent chromium, there has been an increasing demand for chromium-free fingerprint-resistant steel plates that do not use chromate treatment, and several proposals have been made so far.
For example, in Patent Document 1 below, a zinc-based or aluminum-based plated steel sheet is prepared using a surface treatment solution containing a specific phenol resin, a cationic urethane resin, a silane coupling agent, a Ti compound, and a specific acid or salt thereof. A surface-treated steel sheet having a surface treated is disclosed. However, this surface-treated steel sheet does not necessarily have a good balance of properties such as flat part corrosion resistance, corrosion resistance after alkaline degreasing, processed part corrosion resistance, fingerprint resistance, conductivity, paint adhesion, workability, and heat resistance.

Patent Document 2 below discloses a technique using a water-soluble resin or water-based emulsion resin, a specific phenol resin, a specific metal compound, and optionally a metal surface treatment liquid containing an acid and a silane coupling agent. . Although the surface-treated steel sheet using this technique has a relatively good balance of performance, it may not always satisfy the user's request in terms of corrosion resistance (particularly corrosion resistance after alkaline degreasing) and workability.
JP 2003-105562 A JP 2003-13252 A

  Previously proposed chromium-free fingerprint-resistant steel plates have a flat surface corrosion resistance, corrosion resistance after alkaline degreasing, processed portion corrosion resistance, and fingerprint resistance compared to conventional fingerprint-resistant steel plates coated with an organic resin on a chromate film. , Because the performance balance regarding properties such as conductivity, paint adhesion, workability, and heat resistance is insufficient, it cannot be applied to some applications such as home appliances and building materials. It was necessary to make fine adjustments and fine adjustments of the coating amount.

  The present invention is a surface-treated steel sheet that does not contain chromium, and has excellent performance balance such as flat surface corrosion resistance, corrosion resistance after alkaline degreasing, processed portion corrosion resistance, fingerprint resistance, conductivity, paint adhesion, workability, and heat resistance. The purpose is to provide.

  As a result of studying to ensure various properties required for fingerprint-resistant steel sheets without performing chromate treatment, the present inventors have obtained a surface treatment liquid comprising a cationic phenol resin, a cationic urethane resin, and a silane coupling agent. In addition, by including three kinds of metal compounds of manganese, zirconium, and vanadium and a lubricant, the corrosion resistance of the flat surface portion, corrosion resistance after alkaline degreasing, corrosion resistance of the processed portion, fingerprint resistance, electrical conductivity, paint adhesion, A film with good workability and heat resistance can be formed, and the present invention has been achieved.

The present invention relates to a cationic phenol resin comprising a cationic polyurethane resin (A) and polymer molecules having an average polymerization degree of 2 to 50 having a repeating unit represented by the following general formula (1) on the surface of a zinc-based plated steel sheet. (B), a silane coupling agent (C), a manganese compound (D), a zirconium compound (E), a vanadium compound (F), and a lubricant (G) having a particle size of 0.1 to 0.5 μm. The solid content (components A, B, C, G) of each component in the surface treatment liquid or the solid content in metal conversion The blending ratio of (components D, E, F) is a mass ratio,
A / B = 7-120,
C / (A + B) = 0.2-0.75
D / (A + B) = 0.005 to 0.025,
E / (A + B) = 0.01-0.075,
F / (A + B) = 0.001 to 0.025,
G / (A + B) = 0.03-0.4,
It is the surface treatment steel plate characterized by being.

式中、Ｙ₁およびＹ₂は、それぞれ独立して水素または下記一般式(２）もしくは(３)で示されるＺ基を表し、各ベンゼン環当たりのＺ基の平均置換数は０.２〜１.０である。

In the formula, Y ₁ and Y ₂ each independently represent hydrogen or a Z group represented by the following general formula (2) or (3), and the average number of substitutions of Z groups per benzene ring is 0.2 to 1.0.

式(２)および(３)中、Ｒ₁、Ｒ₂、Ｒ₃、Ｒ₄およびＲ₅は、それぞれ独立して水素原子、炭素数１〜１０のアルキル基または炭素数１〜１０のヒドロキシアルキル基を表し、Ａ^-は水酸イオン又は酸イオンを表す。

In the formulas (2) and (3), R ₁ , R ₂ , R ₃ , R ₄ and R ₅ are each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms or a hydroxyalkyl having 1 to 10 carbon atoms. Represents a group, and A ⁻ represents a hydroxide ion or an acid ion.

The adhesion amount of the surface treatment film is preferably in the range of 0.1 to 3 g / m ² .
According to the present invention, there is also provided a method for producing a surface-treated steel sheet, which comprises applying the surface-treated liquid and the surface-treated liquid to a zinc-based plated steel sheet and then drying by heating.

  The surface-treated steel sheet of the present invention does not contain chromium, and is excellent with respect to characteristics such as flat surface corrosion resistance, corrosion resistance after alkaline degreasing, processed portion corrosion resistance, fingerprint resistance, conductivity, paint adhesion, workability, and heat resistance. Indicates the performance balance. Therefore, this surface-treated steel sheet can be used as it is for every application of home appliances and building materials, and fine-tuning of coating components and adhesion amount according to the application, like the known chromium-free fingerprint-resistant surface-treated steel sheet. do not need. This steel plate can be used without painting or with painting.

  The surface-treated steel sheet of the present invention does not contain any chromium, including hexavalent chromium harmful to the human body, and is manufactured using an aqueous surface treatment solution. Since it does not evaporate, the working environment is well maintained and waste liquid treatment is easy.

  As the base material of the surface-treated steel sheet of the present invention, a zinc-based plated steel sheet is used because of its excellent corrosion resistance. The zinc-based plated steel sheet includes a galvanized steel sheet and a zinc alloy plated steel sheet. Examples of zinc-based plating include zinc plating, Zn—Ni alloy plating, Zn—Fe alloy plating (electroplating, alloyed hot dip galvanizing), Zn—Co alloy plating, Zn—Al alloy plating (eg, Zn-5). % Al alloy plating, Zn-55% Al alloy plating), Zn-Mn alloy plating, Zn-Mg alloy plating, Zn-Al-Mg alloy plating, Zn-Sn alloy plating, and the like. These plated steel sheets are used in nickel plating, iron, aluminum, magnesium, tin, cobalt, molybdenum, tungsten, titanium, manganese, lead, antimony, copper, cadmium, arsenic, phosphorus, etc. 1 type or 2 or more types of elements may be contained. Further, it may contain an organic compound or an inorganic compound such as alumina, silica, and titania that can be co-deposited with plating. Further, it may be a multi-layer plated steel sheet in which two or more layers of plating are combined.

  The type of plating is not limited, and electroplating, hot dipping, vapor deposition plating, or the like may be applied depending on the plating type, and these plating methods may be combined. Usually, it is hot dipping or electroplating.

  Preferred as the substrate-plated steel sheet is a hot dip galvanized steel sheet, an electrogalvanized steel sheet, an electro Zn-Ni plated steel sheet, an alloyed hot dip galvanized steel sheet, a molten Zn-5% Al plated steel sheet, and a molten Zn-55% Al plated steel. It is a steel plate.

  The surface treatment liquid used for the surface treatment of the substrate-plated steel sheet is a cationic polyurethane resin (A), a cationic phenol resin (B) having a repeating unit represented by the general formula (1), and a silane coupling agent (C). , A manganese compound (D), a zirconium compound (E), a vanadium compound (F), and a lubricant (G) having a particle size of 0.1 to 0.5 μm. Each of the components (A) to (G) can be used alone or in combination of two or more, and when two or more are used, the total amount is the amount of that component. Each component will be described in more detail below.

(A) Cationic Polyurethane Resin Cationic polyurethane resin (A), which is a water-based resin, has a good adhesion and can form a dense film, and therefore has an effect of improving corrosion resistance due to an outside air blocking effect, and has alkali resistance and heat resistance. From the viewpoint of being a good resin, it is used as a main component of the surface treatment liquid and the surface treatment film in the present invention.

  The cationic polyurethane resin (A) means a polyurethane resin having at least one cationic functional group selected from primary to tertiary amino groups and quaternary ammonium groups. This cationic functional group is the same group as the Z group represented by the formulas (2) and (3) with respect to the phenol resin (B). Examples of the cationic functional group include an amino group, a methylamino group, an ethylamino group, a dimethylamino group, a diethylamino group, a trimethylammonium group, and a triethylammonium group.

  As long as it has at least one cationic functional group, the constituent monomer components (polyol and polyisocyanate) and the polymerization method are not particularly limited. The skeleton of the polyurethane resin is classified into a polyether type, a polyester type, a polycarbonate type, a polycaprolactone type, and the like depending on the polyol component to be used.

  The cationic polyurethane resin (A) is a polyol (which may be any of polyether polyol, polyester polyol, polycarbonate polyol, polycaprolactone polyol) and aliphatic, at least partially substituted with the amino group or ammonium group. It can be obtained by polycondensation with an alicyclic or aromatic polyisocyanate.

  Examples of polyether polyols include polyethylene glycols such as diethylene glycol and triethylene glycol, and polyethylene / propylene glycol. Examples of polyester polyols include alkylene glycols having 1 to 6 carbon atoms (ethylene glycol, propylene glycol, etc.), polyether polyols, polyols such as bisphenol A, hydrogenated bisphenol A, trimethylolpropane, glycerin, and succinic acid. And polyester polyols having a hydroxyl group at the terminal obtained by polycondensation with polybasic acids such as glutaric acid, adipic acid, sebacic acid, phthalic acid, isophthalic acid, terephthalic acid and trimellitic acid. Examples of polyisocyanates include tolylene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, dicyclohexylmethane diisocyanate, cyclohexylene diisocyanate, hexamethylene diisocyanate, lysine diisocyanate and the like.

(B) Cationic phenol resin The cationic phenol resin (B) is blended in the surface treatment liquid in order to improve the corrosion resistance and solvent resistance of the film and improve the liquid stability of the surface treatment liquid. If the resin is only the above-mentioned cationic polyurethane resin (A), even if all the remaining components (C) to (G) are blended in a predetermined ratio, the corrosion resistance and solvent resistance of the film cannot be satisfied.

  The cationic phenol resin (B) is a water-soluble resin composed of a polymer molecule having a repeating unit represented by the general formula (1), and has an average degree of polymerization of 2 to 50. As can be seen from the general formula (1), this resin has hydrogen on the benzene ring with a Z group, that is, a primary to tertiary amino group or a quaternary ammonium group represented by the formula (2) or the formula (3). Can be said to be substituted bisphenol A-formaldehyde resins. This resin is water-soluble, but water resistance improves when dried.

  When the average degree of polymerization of the cationic phenol resin (B) is lower than 2, the effect of imparting solvent resistance becomes insufficient. On the other hand, when the average degree of polymerization exceeds 50, surface treatment treatment may occur due to a decrease in water solubility of the resin or increase in the viscosity of the liquid. The stability of the agent is reduced.

The Z group represented by the formula (2) is a primary to tertiary alkyl and / or hydroxyalkylamino group, and the Z group represented by the formula (3) is a quaternary alkyl and / or hydroxyalkylammonium group. is there. This alkyl group or hydroxyalkyl group (indicated by R _{1 to} R ₅ ) has 1 to 10 carbon atoms. When the carbon number of the alkyl or hydroxyalkyl group is 11 or more, the water solubility of the resin (B) is remarkably lowered, the surface treatment liquid becomes unstable, and the film formability is lowered. This alkyl group or hydroxyalkyl group preferably has 1 to 6 carbon atoms, more preferably 1 to 4 carbon atoms. Specific examples include methyl, ethyl, propyl, butyl, hydroxyethyl, 2-hydroxypropyl, hydroxyisobutyl and the like. Particularly preferred is an alkyl group having 1 to 2 carbon atoms or a hydroxyalkyl group.

When the Z group is an ammonium group represented by the formula (3), the counter ion A ⁻ is a hydroxide ion or an acid ion, and specific examples of the acid ion include sulfate ion, nitrate ion, acetate ion, phosphorus An acid ion, a fluoride ion, etc. can be mentioned.

  The average number of substitution per benzene ring of the Z group is in the range of 0.2 to 1.0. Here, the average number of substitution of Z groups is a numerical value obtained by dividing the total number of introduced Z groups by the total number of benzene rings (that is, average degree of polymerization × 2). When this average substitution number is lower than 0.2, the adhesion of the resin to the substrate surface becomes insufficient and the corrosion resistance is lowered. If this average number of substitutions exceeds 1.0 (that is, on average, more than one Z group is substituted on each benzene ring), the hydrophilicity of the resin becomes too large, and the corrosion resistance also decreases. The average number of substitutions of the Z group is preferably 0.3 to 0.7. When the Z group is only the ammonium group represented by the formula (3), the hydrophilicity-imparting effect is great, and therefore the average substitution number of the Z group is preferably less than 0.5.

  This cationic phenol resin is synthesized by reacting bisphenol A with an amine (or ammonia) that generates formaldehyde and a Z group in the presence of an alkali catalyst in accordance with a general method for synthesizing a phenol-formaldehyde resin. can do. The amine can be allowed to act on bisphenol A in advance before the condensation polymerization, or conversely on the polymer after the condensation polymerization.

(C) Silane coupling agent The silane coupling agent (C) is effective in improving the solvent resistance, corrosion resistance and adhesion of the coating.

  A commercially available product can be used as the silane coupling agent (C). Preferred silane coupling agents are those having at least one functional group selected from an amino group containing active hydrogen, an epoxy group, a vinyl group, a mercapto group, and a methacryloxy group. Specific examples include N- (aminoethyl) -3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2 -(3,4 Epoxycyclohexyl) ethyltrimethoxysilane, vinyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane and the like can be used.

(D) Manganese Compound The manganese compound (D) is effective in improving adhesion to the substrate and improving corrosion resistance.
Examples of the manganese compound (D) include inorganic compounds such as manganese nitrate, manganese sulfate, manganese phosphate, manganese oxide, manganese carbonate, manganese fluoride, manganese chloride; and manganese acetate, manganese lactate, manganese propionate, manganese acetyl. Organic compounds such as acetonate, tetrapropoxy manganese, tetrabutoxy manganese and the like can be mentioned. Preferred manganese compounds are manganese nitrate, manganese phosphate, manganese acetate, manganese lactate, and manganese acetylacetonate.

(E) Zirconium Compound Zirconium compound (E) is effective in improving the corrosion resistance of the film, and is particularly effective in improving alkali resistance. In Patent Document 1 described above, a titanium compound is used as the metal compound. However, since the titanium compound develops color when it coexists with the cationic phenol resin (B), the coating is discolored. On the other hand, zirconium is an element belonging to the same group as titanium. However, it has been found that when a zirconium compound is used, color development when coexisting with the cationic phenol resin (B) can be suppressed.

  Examples of the zirconium compound (E) include inorganic compounds such as zirconium nitrate, zirconium sulfate, zirconium oxide, zircon hydrofluoric acid, zircon sodium fluoride, zircon ammonium fluoride, zirconium ammonium carbonate; and zirconium acetate, zirconium lactate, zirconium stearate. And organic compounds such as zirconium octylate, zircon acetylacetonate, tetrapropoxyzirconium, tetrabutoxyzirconium, zirconium tributoxy systemate. Preferred zirconium compounds are zirconium sulfate, zircon hydrofluoric acid, sodium zircon fluoride, ammonium zircon fluoride, zirconium lactate and zirconium stearate.

(F) Vanadium compound The vanadium compound (F) is effective in improving the corrosion resistance of the film, and is particularly effective in improving the corrosion resistance of the processed part.

  Examples of vanadium compounds (F) are inorganic such as vanadium pentoxide, metavanadate, ammonium metavanadate, sodium metavanadate, vanadium oxytrichloride, vanadium trioxide, vanadium dioxide, vanadium trichloride, vanadyl phosphate, vanadyl sulfate, etc. Compounds; and organic compounds such as vanadium oxyacetylacetonate, vanadium acetylacetonate, tetrapropoxyvanadium, tetrabutoxyvanadium, vanadium tributoxy systemate. Preferred vanadium compounds are vanadium pentoxide, metavanadate, ammonium metavanadate, sodium metavanadate, vanadyl sulfate, vanadium acetylacetonate, and tetrabutoxy vanadium.

  Even if one of the above-mentioned manganese compound (D), zirconium compound (E) and vanadium compound (F) is missing, the corrosion resistance of the film is lowered. Therefore, in the present invention, in order to ensure a good performance balance of the surface-treated steel sheet, it is necessary to contain at least one of these three kinds of metal compounds in the film.

(G) Lubricant:
A lubricant is added to the surface treatment liquid in order to improve the lubricity and workability (slidability) of the film (which can be evaluated by resistance to mold galling). As the lubricant, since the surface treatment liquid is aqueous, it is preferable to use an aqueous wax having excellent dispersibility in the aqueous treatment liquid. The water-based wax may be any of polyolefin-based wax, ester-based wax, and hydrocarbon-based wax. A lubricant having a particle size in the range of 0.1 to 0.5 μm is used. Lubricants with a particle size of less than 0.1 μm have poor processability, and lubricants with a particle size of more than 0.5 μm are difficult to coexist because of insufficient dispersion in the surface treatment solution. However, if the amount is small, a lubricant having a particle size in the above range can coexist, but the amount of such a lubricant is not considered as the amount of the component (G).

The blending ratio of each component in the surface treatment solution should satisfy the following formula:
A / B = 7-120
C / (A + B) = 0.2-0.75
D / (A + B) = 0.005 to 0.025,
E / (A + B) = 0.01-0.075,
F / (A + B) = 0.001 to 0.025,
G / (A + B) = 0.03-0.4.

In said formula, AG is the mass as a solid content of component (A)-(G), respectively. However, metal compounds (D), (E), and (F) are solid contents in terms of metals of each compound.
When the mass ratio of A / B is smaller than 7, the cationic phenol resin (B) is too much, and the heat resistance and water resistance of the film are lowered. On the other hand, when the mass ratio of A / B is larger than 120, the amount of the cationic phenol resin (B) is too small, and the general corrosion resistance and solvent resistance are lowered.

  About component (C)-(G), a compounding quantity is prescribed | regulated as mass ratio with respect to the total amount of resin component (A) and (B), ie, (A + B). If each of the components (C) to (G) is less than the specified amount, the effect of each component described above will be insufficient. On the other hand, if the amount is too large, the silane coupling agent (C) decreases the corrosion resistance of the processed part, the manganese compound (D) and the zirconium compound (E) decrease in liquid stability, and the vanadium compound (F) exhibits heat resistance. In the case of reduction and lubricant (G), problems such as coil collapse due to reduction in the static friction coefficient arise.

  The surface treatment liquid used in the present invention is aqueous. An aqueous system means that the solvent is mainly composed of water. The solvent may be water alone, but one or more water-soluble organic solvents such as monohydric or polyhydric alcohols, ketones and cellosolves are used for the purpose of adjusting the drying property of the film and the viscosity of the treatment agent. You may use together.

  The surface treatment liquid may contain components other than the above components as desired. Such components include pH adjusters (acids or bases), fillers, surfactants, antifoaming agents, leveling agents, antibacterial agents, colorants, etc., and should be added within a range that does not impair the performance of the film. Can do.

The surface-treated steel sheet of the present invention has a surface-treated film formed on the surface of a galvanized steel sheet as a base material by applying the above-described surface treatment liquid and drying.
The surface treatment liquid can be applied using, for example, a roll coater (3-roll method, 2-roll method, etc.), a squeeze coater, a die coater, or the like. Alternatively, a method of adjusting the coating amount by an air knife or roll squeezing after dip coating or spray coating can be employed.

  Prior to this coating, the surface of the plated steel plate can be adjusted by one or more of degreasing, pickling, hot water washing, detergent washing, etc., and in either case, the surface can be thoroughly washed with water at the end. preferable. The liquid temperature of the treatment agent at the time of application may be room temperature, but it may be cooled or heated as desired.

  It is appropriate that the drying after applying the surface treatment liquid is performed at a maximum plate temperature (PMT) in the range of 50 to 250 ° C., preferably 60 to 220 ° C. If this heating temperature is less than 50 ° C., drying takes a long time, and corrosion resistance may be insufficient due to residual moisture in the film or insufficient curing. On the other hand, a drying temperature exceeding 250 ° C. is not only uneconomical but also may cause defects in the film and reduce the corrosion resistance. As the heating means, for example, a dryer, a hot air furnace, a high frequency induction heating furnace, an infrared furnace, or the like can be used.

  During this coating and drying, it is estimated that the cationic urethane resin (A) and the phenol resin (B) form a film on the base material to form a surface treatment film having an excellent shielding effect against the outside air. The Furthermore, the silane coupling agent (C) reacts with the metal surface of the base material to build a dense three-dimensional cross-linked structure, and three kinds of metal compounds (D) to (F) are also added to improve corrosion resistance and water resistance. Excellent film.

The adhesion amount of the surface treatment film thus formed is preferably in the range of 0.1 to 3 g / m ² . When the coating amount is thinner than 0.1 g / m ² , the corrosion resistance becomes insufficient. When corrosion resistance is required, 0.5 g / m ² or more is preferable. On the other hand, when the adhesion amount exceeds 3 g / m ² , conductivity and workability deteriorate. More preferably, it is 2.5 g / m ² or less.

  On the surface treatment film thus formed, an organic resin film can be formed as the second layer film. The organic resin film of the second layer is, for example, epoxy resin, polyhydroxy polyether resin, acrylic copolymer resin, ethylene-acrylic acid copolymer resin, alkyd resin, polybutadiene resin, phenol resin, polyurethane resin, polyamine resin, A resin film selected from polyphenylene resins, a mixture of two or more of these resins, or an addition polymer can be used.

The adhesion amount of the second layer film may be the same as the adhesion amount of the surface treatment film as the first layer. However, the total adhesion amount of the first layer and the second layer is preferably 5 g / m ² or less, more preferably 3 g / m ² or less.

  In addition, you may form the surface treatment film | membrane mentioned above on either the single side | surface of a base-plated steel plate, or both surfaces. When forming on one side, the back surface of the plated steel sheet may be left untreated or another surface treatment film may be formed.

[Adjustment of surface treatment solution]
A surface treatment solution having the composition shown in Table 1 was prepared by mixing materials selected from the following for each of the components (A) to (G). For the silane coupling agent (C), two kinds of materials were used in combination in some cases. For other components, it is possible to use two or more materials. For comparison, a surface treatment solution not using some components was also prepared. Table 1 shows the types of components used in the preparation of the surface treatment liquid, the amounts of components (A) and (B) (parts = parts by mass), A / B mass ratios, and components (C) to (G). The mass ratio with respect to (A + B) is shown.

(A) Cationic polyurethane resin A1: Polyester cationic polyurethane resin (Adekabon titer HUX-680 manufactured by Asahi Denka),
A2: polyether-based cationic polyurethane resin (Daiichi Kogyo Seiyaku Superflex 600),
A3: Polycarbonate-based cationic polyurethane resin (Daiichi Kogyo Seiyaku Superflex 650).

(B) Cationic phenol resin B1: n = 5, Y ₁ = —CH ₂ N (CH ₃ ) _2, Y ₂ = H, Z substitution degree = 0.5,
_{B2: n = 10, Y 1} = -CH 2 N (CH 3) (C 2 H 4 OH), Y 2 = H, Z substitution degree = 1.0.

(C) Silane coupling agent C1: 3-aminopropyltriethoxysilane,
C2: 3-glycidoxypropyltrimethoxysilane,
C3: 3-mercaptopropyltrimethoxysilane,
C4: vinyltriethoxysilane,
C5: 3-methacryloxypropyltrimethoxysilane.

(D) Manganese compound D1: Manganese acetate
D2: Manganese nitrate
D3: Manganese lactate,
D4: Manganese acetylacetonate
D5: Manganese phosphate.

(E) zirconium compound E1: zirconium nitrate,
E2: zircon hydrofluoric acid,
E3: zirconium stearate,
E4: zirconium lactate,
E5: Zirconium sulfate.

(F) vanadium compound F1: vanadium pentoxide,
F2: tetrabutoxyvanadium,
F3: vanadium acetylacetonate,
F4: ammonium metavanadate
F5: vanadyl sulfate.

(G) Lubricant G1: Nonionic polyethylene wax / particle diameter of 0.1 μm or more, less than 0.25 μm,
G2: Nonionic polyethylene wax / grain size of 0.25 μm or more and 0.5 μm or less.

[Production of surface-treated steel sheet]
An electrogalvanized steel sheet having a thickness of 0.8 mm (adhesion amount per side of 20 g / m ² ) was used as a base material, and this was subjected to alkaline degreasing and water washing. It was applied on one side by a bar coater and dried by heating (baking) to form a surface treatment film. Table 1 shows the film thickness and the heating temperature (PMT, maximum ultimate plate temperature) of the formed film.

  The surface treatment film of the surface-treated steel sheet thus produced was evaluated for performance as follows. For reference, performance evaluation was also performed on a surface-treated steel sheet in which a zirconium compound was replaced with a titanium compound as a metal compound. The test results are also shown in Table 1.

[Evaluation methods]
(1) Corrosion resistance (Flat part)-Using a test piece of a non-processed surface-treated steel sheet, it was evaluated as follows according to the white rust occurrence surface rate after 120 hours of salt spraying based on JIS-Z-2371:
A: Less than 5%, O: 5% or more, less than 10%, Δ: 10% or more, less than 30%, X: 30% or more, less than 50%, XX: 50% or more.

(Alkali = Corrosion resistance after alkali degreasing)-Using an unprocessed surface-treated steel sheet test piece, an alkali degreasing agent CL-364S (20 g / L, 60 ° C, 10 seconds spray, spray pressure 0.5 kg / cm ² ). After degreasing, spray water washing was performed for 10 seconds, and then the white rust generation area ratio after 120 hours of salt water spraying based on JIS-Z-2371 was evaluated as follows:
A: Less than 5%, O: 5% or more, less than 10%, Δ: 10% or more, less than 30%, X: 30% or more, less than 50%, XX: 50% or more.

(Processed part)-Using an Erichsen 7 mm extruded surface-treated steel sheet test piece, the following evaluation was made based on the white rust generation surface rate after 120 hours of salt spraying based on JIS-Z-2371:
A: Less than 5%, O: 5% or more, less than 10%, Δ: 10% or more, less than 30%, X: 30% or more, less than 50%, XX: 50% or more.

(2) Ethanol resistance (solvent resistance)
The surface treatment film of the test piece of the surface-treated steel sheet was evaluated as follows by the appearance after rubbing 5 times with gauze soaked with ethanol:
A: The rubbing trace is inconspicuous, O: The rubbing trace is slightly conspicuous, Δ: The rubbing trace is conspicuous, x: The rubbing trace is very conspicuous.

(3) Mold galling resistance (workability or slidability)
A test piece of an appropriate size is molded into a U shape using a crank press (die and punch shoulder R = 5 mm, clearance: −10% of the plate thickness), and the molded product (sliding with a mold) is performed. According to the appearance of the received part), it was evaluated as follows:
○: No discoloration, Δ: Discolored partially black, ×: Discolored entirely black.

(4) Heat resistance The test piece of the surface-treated steel plate was heated at 150 ° C. for 20 minutes, and the color difference Δb (b value difference in the Hunter color system) before and after heating was measured and evaluated according to the following criteria:
○: Δb is 1 or less, Δ: 1 <Δb <2, X: Δb is 2 or more.

(5) Water resistance The specimen of the surface-treated steel sheet immediately after baking (heat drying) was water-cooled, and the eluate from the film was measured by XRF (fluorescence X-ray analysis) and evaluated according to the following criteria:
○: No elution, x: Elution.

(6) Film color tone The b value (b value in the Hunter color system) of the test piece of the surface-treated steel sheet was measured and evaluated according to the following criteria:
○: b is 0.5 or less, x: b exceeds 0.5.

(7) Fingerprint resistance After measuring the color tone (L1, a1, b1) of the hunter color system of the specified part of the test piece film, apply petrolatum to it and wipe it off with Kimwipe (Tech Jam). Then, the color tone (L2, a2, b2) of the same part was measured again. The color difference (ΔE = √ {(L2−L1) ² + (a2−a1) ² + (b2−b1) ² } of the ^two measurements was evaluated as follows:
○: ΔE is 2 or less, x: ΔE exceeds 2.

表１からわかるように、本発明にしたがった表面処理液から皮膜を形成した実施例１〜９３では、平面部、アルカリ（アルカリ脱脂後）および加工部のすべての耐食性が良好であり、さらに耐溶剤性（耐エタノール性）、加工性（耐型かじり性）、耐熱性、皮膜密着性（耐水性）、耐指紋性もすべて良好であった。すなわち、本発明の表面処理鋼板は性能バランスに優れ、表面処理鋼板に要求される各種の特性がいずれも良好である。

As can be seen from Table 1, in Examples 1 to 93 in which a film was formed from the surface treatment solution according to the present invention, all of the corrosion resistance of the flat portion, the alkali (after alkali degreasing) and the processed portion were good, Solvent resistance (ethanol resistance), workability (mold galling resistance), heat resistance, film adhesion (water resistance), and fingerprint resistance were all good. That is, the surface-treated steel sheet of the present invention is excellent in performance balance, and various properties required for the surface-treated steel sheet are all good.

  On the other hand, if any one of the components (B) to (G) is not present in the comparative example, or the amount thereof is too small, the components (B) to (F) may be further resistant to corrosion and depending on the case. However, the processability of the component (G) decreased. On the other hand, when the component (B) is too much, the heat resistance and water resistance are remarkably lowered. When the component (C) is too much, the corrosion resistance of the processed part is lowered. When the component (F) is too much, the heat resistance is lowered.

Claims (2)

On the surface of the zinc-based plated steel sheet, a cationic polyurethane resin (A) and a cationic phenol resin (B) comprising polymer molecules having an average degree of polymerization of 2 to 50 having a repeating unit represented by the following general formula (1): A silane coupling agent (C), a manganese compound (D), a zirconium compound (E), a vanadium compound (F), and a lubricant (G) having a particle size of 0.1 to 0.5 μm. It has a surface treatment film formed by applying and drying an aqueous surface treatment liquid, and the solid content (components A, B, C, G) of each component in the surface treatment liquid or the solid content (component D, E, F) is a mass ratio,
A / B = 7-120,
C / (A + B) = 0.2-0.75
D / (A + B) = 0.005 to 0.025,
E / (A + B) = 0.01-0.075,
F / (A + B) = 0.001 to 0.025,
G / (A + B) = 0.03-0.4,
A surface-treated steel sheet, characterized in that

In the formula, Y ₁ and Y ₂ each independently represent hydrogen or a Z group represented by the following general formula (2) or (3), and the average number of substitutions of Z groups per benzene ring is 0.2 to 1.0.

In the formulas (2) and (3), R ₁ , R ₂ , R ₃ , R ₄ and R ₅ are each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms or a hydroxyalkyl having 1 to 10 carbon atoms. Represents a group, and A ⁻ represents a hydroxide ion or an acid ion. The surface-treated steel sheet according to claim 1, wherein the surface treatment film has an adhesion amount of 0.1 to 3 g / m ² .