CN107109111B - Coating material for hot-dip galvanized steel sheet, method for treating steel sheet, method for producing surface-treated steel sheet, and surface-treated steel sheet - Google Patents

Abstract

The invention provides a coating for hot-dip galvanized steel sheets, which is used for endowing the hot-dip galvanized steel sheets with excellent appearance characteristics, excellent friction resistance and excellent corrosion resistance. The coating material for hot dip galvanized steel sheet of the present invention contains a cationic polyurethane resin (A) having at least one cationic functional group selected from a primary to tertiary amino group and a quaternary ammonium salt group, the cationic polyurethane resin (A) having a polycarbonate structural unit and a bisphenol structural unit, a temperature (Tg1) at which a maximum peak of a loss modulus E ' of the cationic polyurethane resin (A) is exhibited is in a range of-60 ℃ to-5 ℃, and a loss tangent tan, which is a ratio of the loss modulus E ' to a storage modulus E ' of the cationic polyurethane resin (A)δConsisting of one peak.

Description

Coatings for hot-dip galvanized steel sheets, methods for processing steel sheets, and surface-treated steels Sheet manufacturing method and surface-treated steel sheet

technical field

The present invention relates to a coating for hot-dip galvanized steel sheet, a method for processing a hot-dip galvanized steel sheet, a method for producing a surface-treated hot-dip galvanized steel sheet, and a surface-treated hot-dip galvanized steel sheet.

Background technique

Conventionally, zinc-based plated steel sheets including molten zinc plated steel sheets, molten zinc-5% aluminum alloy plated steel sheets, and molten zinc alloy plated steel sheets have been widely used in home appliances, building materials, and the like. In addition, as a method of producing a zinc-based plated steel sheet, for example, a steel sheet as a target object is immersed in a molten zinc bath, and a dipping method (so-called "hot-dip galvanizing") is used to perform plating. ”), a method of applying molten zinc plating to the entire surface, and the resulting steel sheet is also referred to as a hot-dip molten zinc-coated steel sheet. In addition, in the dipping method by hot-dip plating (hereinafter, also referred to as hot-dip plating method), zinc plating by air knife or the like, which is performed in CGL (Continuous Galvanizing Line), is not performed. adhesion control.

Among zinc-based plated steel sheets, for the purpose of improving corrosion resistance, steel sheets that have been chromated with a treatment solution containing chromic acid, dichromic acid, or salts thereof as a main component are widely used.

However, since a chromate-treated film generally contains hexavalent chromium having a high environmental load, there has been an increasing demand for hexavalent-chromium-free treatment of the treated film in recent years, and various techniques have been proposed.

For example, Patent Document 1 discloses a method of preventing corrosion on the surface of a steel material by bringing an aqueous solution containing a vanadate and a water-soluble acrylic resin into contact with the surface of a zinc-plated steel material.

prior art literature

Patent Literature

Patent Document 1: Japanese Patent Laid-Open No. 2002-146554.

SUMMARY OF THE INVENTION

The problem to be solved by the invention

On the other hand, in recent years, zinc-based plated steel sheets have been expanded to various applications, and not only further improvement in corrosion resistance but also improvement in other properties have been sought. For example, the improvement of the appearance characteristics of the zinc-based plated steel sheet, or the marking of the film (film placed on the zinc-based plated steel sheet) as a mark when wiping with a cloth dipped in alcohol or the like during assembly work, etc. The ease of peeling of the ink (magic ink) operation, that is, the improvement of the resistance of the film (hereinafter, referred to as rub resistance). In particular, improvement of the above-mentioned properties (corrosion resistance, appearance properties, and friction resistance) is strongly demanded for hot-dip hot-dip zinc-coated steel sheets.

The inventors of the present invention conducted evaluations of the above-mentioned various properties on a steel sheet obtained by applying the method described in Patent Document 1 to a hot-dip hot-dip galvanized steel sheet, and found that it was impossible to simultaneously satisfy the appearance properties, Friction resistance and corrosion resistance, thus requiring further improvement.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a hot-dip galvanized steel sheet (or a molten zinc plated steel sheet or a zinc-based plated steel sheet) with excellent appearance properties and excellent friction resistance. Coatings for hot-dip hot-dip galvanized steel sheets (or, molten zinc plated steel sheets or zinc-based plated steel sheets) with excellent corrosion resistance.

means of solving problems

As a result of earnestly examining the above-mentioned subject, the inventors of the present invention have found that the desired effects can be obtained by using a coating material containing a cationic urethane resin exhibiting predetermined properties.

More specifically, it was found that the above-mentioned object can be achieved by the following configuration.

(1) A coating material for hot-dip molten zinc plated steel sheet, which contains a cationic polyurethane resin (A) having at least one cationic functional group selected from primary to tertiary amino groups and quaternary ammonium salt groups, a cationic polyurethane resin (A) ) has a polycarbonate structural unit and a bisphenol structural unit, the temperature (Tg1) at which the maximum peak value of the loss modulus E'' of the cationic polyurethane resin (A) is exhibited is in the range of -60°C to -5°C, and the cationic The ratio of the loss modulus E'' to the storage modulus E' of the urethane resin (A), that is, the loss tangent tan δ , consists of one peak.

(2) The coating material for hot-dip zinc-coated steel sheets according to (1), wherein the peak temperature (Tg2) of the loss tangent tan δ is in the range of -50°C to -2°C.

(3) The coating material for hot-dip galvanized steel sheets according to (1) or (2), which further contains a phosphoric acid compound (B).

(4) The coating material for hot-dip galvanized steel sheets according to (3), wherein the phosphoric acid compound (B) contains at least one selected from the group consisting of orthophosphoric acid, condensed phosphoric acid, and salts thereof.

(5) The coating material for hot-dip galvanized steel sheet according to any one of (1) to (4), wherein the amine value (AV) of the cationic polyurethane resin (A) is 2.0 to 5.0 mgKOH/ g.

(6) The paint for hot-dip molten zinc plated steel sheet according to (5), wherein the content ratio (mass %) (BV) of the phosphoric acid compound (B) to the solid content of the cationic urethane resin and the amine value The ratio ((BV)/(AV)) is 0.1 to 9.5.

(7) The coating material for hot-dip galvanized steel sheets according to any one of (1) to (6), which further contains a trivalent chromium compound (C).

(8) A method of processing a hot-dip hot-dip galvanized steel sheet, wherein the hot-dip hot-dip galvanized steel sheet is subjected to hot-dip galvanization using the coating material for a hot-dip galvanized steel sheet according to any one of (1) to (7). Treatment of plated steel sheets.

(9) A method for producing a surface-treated hot-dip hot-dip galvanized steel sheet by combining the paint for a hot-dip galvanized steel sheet described in any one of (1) to (7) with a hot-dip galvanized steel sheet The plated steel sheets were contacted to produce a surface-treated hot-dip galvanized plated steel sheet having a hot-dip galvanized plated steel sheet and a film disposed on the surface.

(10) A surface-treated molten zinc plated steel sheet obtained by the production method described in (9).

Invention effect

According to the present invention, it is possible to provide a hot-dip galvanized steel sheet (or a molten zinc plated steel sheet or a zinc-based plated steel sheet) with excellent appearance properties, excellent friction resistance, and excellent corrosion resistance. Coatings for hot-dip hot-dip galvanized steel sheets (or, molten zinc plated steel sheets or zinc-based plated steel sheets).

Furthermore, it is possible to provide a hot-dip hot-dip galvanized steel sheet (or a molten zinc-coated steel sheet) in which a process of hot-dip hot-dip zinc-coated steel sheet (or a molten zinc-coated steel sheet or a zinc-based plated steel sheet) is performed using the paint. Coated steel sheet or zinc-based coated steel sheet); Hot-dip hot-dip hot-dip galvanized steel sheet (or, molten zinc-coated steel sheet or zinc-based coated steel sheet) and coating disposed on the surface or zinc-based plated steel sheets); and steel sheets thereof.

Moreover, although the coating material for hot-dip galvanized steel sheets of the present invention is a hexavalent chromium-free technology, the performance is greatly improved by including trivalent chromium. Moreover, even if it does not contain trivalent chromium, the desired effect is exhibited.

Detailed ways

Hereinafter, the paint for hot-dip galvanized steel sheets of the present invention (hereinafter, also simply referred to as "paint") will be described in detail. The reason why the desired effect is obtained by using the coating material of the present invention is presumed as follows.

First, as a reason for the improvement of external appearance characteristics, the point which shows the temperature (Tg1) which shows the maximum peak of the loss modulus E" of a cationic urethane resin is in the range of -60 degreeC - -5 degreeC. The inventors of the present invention have found that the above-mentioned temperature (Tg1) correlates with the appearance properties and abrasion resistance of the film. That is, the loss modulus E'' is an index indicating the viscosity of the object, and when the temperature at which the maximum peak of the loss modulus E'' is shown is too low, the resin exhibits good fluidity, and the flatness of the film is improved, thereby obtaining excellent However, the hardness of the formed film is poor, resulting in a decrease in friction resistance. On the other hand, when the above-mentioned temperature is too high, the formed film has excellent hardness and excellent friction resistance, but the fluidity of the resin decreases and the appearance properties are poor. In the present invention, it has been found that when the temperature (Tg1) of the cationic polyurethane resin is within the above-mentioned range, both appearance properties and friction resistance can be achieved. In addition, the said abrasion resistance means the resistance of a film|membrane to the operation|work of the magic ink (magic ink) marked as a mark at the time of wiping off with the cloth dipped in alcohol or the like during the assembly operation.

Moreover, as a reason for the improvement of corrosion resistance, the point which the loss tangent tan δ of the cationic urethane resin consists of one peak is mentioned. In general, the urethane resin tends to form a sea-island structure having two or more domains of a soft segment and a hard segment in a film form due to its resin skeleton. Therefore, when the dynamic viscoelasticity measurement is performed, two or more peaks are observed in the loss tangent tan δ . On the other hand, in the cationic urethane resin used in the present invention, the loss tangent tan δ is composed of one peak, the above-mentioned sea-island structure is not easily formed in the film, a uniform film is formed, and corrosion resistance is improved as a result.

Furthermore, in order to ensure good surface coating adhesion and impact resistance, the peak temperature (Tg2) of the loss tangent tan δ of the cationic urethane resin is preferably in the range of -50°C to -2°C. Depending on the use environment of the product to which the coating material of the present invention is applied, processing may be performed in a cold region. If it is a coating material containing a component with a high peak temperature of loss tangent tan δ used for surface treatment, the coating film is hard, and therefore, when the coating is processed at low temperature in winter, the coating adhesion of the surface coating is insufficient. The coating film peels easily. In addition, if the coating material used for surface treatment contains a component with a low peak temperature of loss tangent tan δ , the film is relatively soft, and therefore, the impact resistance is insufficient especially when processing at high temperature in summer, and it is easy to produce The coating film is peeled off. On the other hand, when the peak temperature (Tg2) of the loss tangent tan δ is in the range of -50°C to -2°C, the film has sufficient flexibility and hardness at both low temperature and high temperature, and exhibits sufficient flexibility. Surface coating adhesion and impact resistance.

Furthermore, in order to ensure favorable storage stability, it is preferable that the amine value of the cationic polyurethane resin is in the range of 2.0 to 5.0 mgKOH/g. The cationic functional group in the cationic polyurethane resin contributes to making the cationic polyurethane resin water-soluble or water-dispersible. Therefore, when there are few cationic functional groups, in other words, when the amine value is low, the stability of the cationic polyurethane resin is insufficient, and redispersion in the coating material may occur, but precipitation of the resin is likely to occur. Therefore, in order to improve the stability of the cationic polyurethane resin, it is desirable to increase the number of cationic functional groups, in other words, to increase the amine value. However, when the hydrophilic group in the resin is excessively increased, that is, the amine value is too high, the opposite is true. Since the cationic urethane resin is water-solubilized, the viscosity is increased, the coating material is thickened, and the redispersibility of the coating material may be affected. In addition, there are cases where the coating workability is affected due to the thickening. Therefore, it is presumed that good storage stability can be obtained by controlling the amine value of the cationic polyurethane resin to be in the range of 2.0 to 5.0 mgKOH/g.

Moreover, as another effect of the coating material of this invention, the point which is excellent in phosphate treatment property can also be mentioned. As a reason for the excellent phosphate treatability, the aspect of using a cationic urethane resin having a predetermined functional group can be mentioned. It is presumed that the cationic functional group in the cationic urethane resin in the film formed on the hot-dip galvanized steel sheet interacts with the phosphoric acid present in the phosphoric acid compound, resulting in the formation reaction of phosphates such as zinc phosphate in the phosphate treatment. The starting point, the phosphate treatability is improved. The content ratio (mass %) (BV) of the phosphoric acid compound to the solid content of the cationic urethane resin and the ratio of the amine value (BV)/(AV) are not particularly limited, and examples thereof include 0.05 to 20, among which, the preferred 0.1 to 9.5, more preferably 0.5 to 9.0, still more preferably 0.5 to 6.0. By setting (BV)/(AV) in the above-mentioned range (0.1 to 9.5), it is presumed that the starting point of the formation reaction of phosphate is more favorably generated on the film, and more excellent phosphate treatment properties can be obtained. In this case, when there are relatively many phosphoric acid compounds, that is, when (BV)/(AV) is large, a relatively large amount of phosphoric acid compounds are eluted in the phosphate treatment solution, so that the formation of the phosphate film tends to be delayed in many cases. Conversely, when the phosphoric acid compound is relatively small, that is, when (BV)/(AV) is small, the interaction between the phosphoric acid compound and the cationic functional group of the cationic urethane resin is relatively small, so that the phosphate treatment solution causes a problem. The swelling or dissolution of the cationic urethane resin is reduced, and the formation of the phosphate film tends to be delayed.

In addition, the phosphate treatment refers to a treatment using a phosphate treatment liquid mainly composed of zinc phosphate, manganese phosphate, magnesium phosphate, etc., which are suitable for coating primers and the like. Coating-type phosphate treatment has become one form of phosphate treatment. The coating-type phosphate treatment refers to the formation of fine and dense particles by applying a coating-type phosphate treatment solution to the surface of the object to be treated (for example, a zinc-coated steel sheet such as a hot-dip galvanized steel sheet). Crystallization of zinc phosphate, treatment to improve the sliding resistance of the friction joint surface with the strong bolt, etc.

It should be noted that the coating material of the present invention can be suitably applied to hot-dip hot-dip galvanized steel sheets, and can also be suitably applied to hot-dip galvanized steel sheets, molten galvanized steel sheets manufactured by CGL (continuous Zinc-based plated steel sheets such as zinc-5% aluminum alloy plated steel sheets, molten zinc-55% molten aluminum alloy plated steel sheets, alloyed molten zinc plated steel sheets, electro-galvanized steel sheets produced by EGL (electro-galvanizing line), etc. , can improve the above-mentioned various characteristics (appearance characteristics, friction resistance, corrosion resistance, surface coating adhesion, impact resistance, phosphate treatment, etc.). In other words, the paint of the present invention can be suitably applied to a zinc-based plated steel sheet, and can also be used as a paint for a zinc-based plated steel sheet. In particular, it can be suitably applied to hot-dip hot-dip galvanized steel sheets, hot-dip galvanized steel sheets produced by CGL (Continuous Molten Galvanized Sheet Line), etc., molten zinc-5% aluminum alloy plated steel sheets, and molten zinc-55 % A molten aluminum alloy plated steel sheet, an alloyed molten zinc plated steel sheet, etc., a molten zinc plated steel sheet obtained by performing a plating treatment with molten zinc can also be used as a coating material for a molten zinc plated steel sheet.

The coating material of the present invention contains at least the cationic urethane resin (A).

Hereinafter, various components contained in the paint will be described in detail, and then, a method of processing a hot-dip galvanized steel sheet using a paint (in other words, manufacturing a hot-dip galvanized steel sheet having a The surface treatment of the cortex on the surface treats thermal dipping and melting zinc plating steel plate, and the surface treatment of hot -dip thermal melting zinc -plating steel plate manufacturing method) is made in detail.

<Cationic polyurethane resin (A)>

The coating material of the present invention contains a cationic polyurethane resin (A) having at least one cationic functional group selected from primary to tertiary amino groups and quaternary ammonium salt groups.

The anionic resins used in the prior art generally tend to be poor in alkali resistance and excellent in acid resistance. When the alkali resistance is poor, the film is easily dissolved and peeled off by the alkali degreasing step after film formation, etc., and therefore, the corrosion resistance decreases. In addition, since it is excellent in acid resistance, it is difficult to perform phosphate treatment in many cases. On the other hand, since the cationic polyurethane resin (A) is excellent in alkali resistance, it is also excellent in corrosion resistance after the alkali degreasing step. In addition, the urethane resin film becomes tough due to the hydrogen bond derived from the urethane bond in the molecule, and the corrosion resistance is improved. In addition, in contrast, there are cases where it has a cationic functional group, and since acid resistance is low, it is easy to perform phosphate treatment as a property of the resin.

(cationic functional group)

Examples of the cationic functional group contained in the cationic polyurethane resin (A) include amino groups, methylamino groups, ethylamino groups, dimethylamino groups, diethylamino groups, trimethylamino groups, and triethylamino groups. etc., but is not particularly limited as long as it is a primary to tertiary amino group or a quaternary ammonium salt group.

In addition, the cationic functional group in cationic urethane resin (A) contributes to making cationic urethane resin (A) water-soluble or water-dispersible. It should be noted that the dissolution or dispersion of the cationic urethane resin (A) in water can be achieved based on the self-solubility or self-dispersibility of the cationic urethane resin (A) in water, and can also be achieved by means of a cationic surfactant (eg, alkyl quaternary ammonium salts) and/or nonionic surfactants (eg, alkyl phenyl ethers).

(Temperature (Tg1) at which the maximum peak value of loss modulus E'' is exhibited)

The temperature (Tg1) at which the maximum peak value of the loss modulus E'' of the cationic urethane resin (A) is exhibited is in the range of -60°C to -5°C. In terms of at least one of excellent properties, surface coating adhesion, impact resistance, and storage stability (hereinafter, also simply referred to as "the aspect in which the effects of the present invention are more excellent"), it is preferably -55°C to -10°C, more preferably -50°C to -15°C.

When the temperature (Tg1) is less than -60°C, the friction resistance is poor, and when the temperature exceeds -5°C, the appearance of the film is poor.

It should be noted that the above-mentioned maximum peak refers to a loss modulus curve obtained by a dynamic viscoelasticity measurement to be described later (the loss modulus in the graph in which the horizontal axis is the temperature and the vertical axis is the loss modulus). The largest peak among the peaks observed in the temperature dependence curve of . The peak value can also be referred to as the so-called maximum value.

(loss tangent tan δ )

The ratio of the loss modulus E'' to the storage modulus E' of the cationic polyurethane resin (A) (loss modulus E''/storage modulus E'), that is, the loss tangent tan δ , consists of one peak (only with one peak). That is, the loss tangent tan δ curve obtained by the dynamic viscoelasticity measurement described later (temperature dependence of loss tangent tan δ in the graph in which the horizontal axis is the temperature and the vertical axis is the loss tangent tan δ curve), consists of one peak (has only one peak). In other words, it means that two or more peaks do not exist. As described above, when two or more peaks are observed, the formed film is microscopically uneven and has poor corrosion resistance.

(peak temperature of loss tangent tan δ (Tg2))

The range of the peak temperature (Tg2) of the loss tangent tan δ is not particularly limited, but -50°C is preferable because the effects of the present invention (especially, the surface coating adhesion and impact resistance) are more excellent. ~-2°C, more preferably -48°C to -5°C, further preferably -45°C to -10°C.

As a method for measuring dynamic viscoelasticity, a dynamic viscoelasticity measuring device "RSAG2" manufactured by TA Instruments was used to measure the lateral direction ( TD), at a vibration frequency of 10 Hz and a strain of 0.1%, measured from -100 °C to 200 °C at a heating rate of 5 °C/min, and calculated the storage modulus E', loss modulus E'' and loss tangent tan δ .

The above-mentioned properties (loss modulus E″, loss tangent tan δ ) of the cationic urethane resin (A) contained in the coating material of the present invention can be appropriately adjusted by controlling the structure or synthesis method.

For example, the temperature (Tg1) can be controlled by the amount and molecular weight of the polyol that forms part of the soft segment of the cationic urethane resin (A), or the temperature during polymerization. When the amount of polyol is large, the temperature (Tg1) tends to be low, and when the amount is small, the temperature (Tg1) tends to be high.

In order not to observe two or more loss tangent tan δ peaks, for example, there is a method of controlling the molecular weight of the polyol constituting the soft segment of the cationic urethane resin (A) or the temperature during polymerization.

(Structure of Urethane Resin)

The cationic polyurethane resin (A) has a polycarbonate structural unit and a bisphenol structural unit. In other words, the cationic polyurethane resin (A) has a repeating unit of a polycarbonate structure and a repeating unit of a bisphenol structure as repeating units constituting the resin.

Although the carbonate structural unit is excellent in flexibility and adhesiveness, the hydrolysis resistance of the film tends to be poor when wetted with water or the like. Although the bisphenol structural unit is excellent in hydrolysis resistance, it is hard and inferior in flexibility, and tends to be easily damaged by friction or the like.

That is, if it does not have a polycarbonate structural unit and a bisphenol structural unit, corrosion resistance and friction resistance are inferior to those which have a polycarbonate structural unit and a bisphenol structural unit.

In the present invention, by combining the two and controlling the temperature (Tg1) at which the maximum peak value of the loss modulus E″ is shown to be in the range of -60°C to -5°C, both excellent corrosion resistance and friction resistance can be obtained. properties and excellent appearance properties.

A polycarbonate structural unit is a repeating unit having a plurality of carbonate bonds (-O-C(=O)-O-) in its structure. Generally, a polyurethane resin is produced by the reaction of a polyol and a polyisocyanate. Therefore, as a method of introducing a carbonate structural unit into a cationic urethane resin (A), the method of manufacturing a cationic urethane resin (A) using a polycarbonate polyol is mentioned.

As the polycarbonate polyol, ethylene glycol, propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3- Methyl-1,5-pentanediol, 1,9-nonanediol, 1,8-nonanediol, neopentyl glycol, diethylene glycol, dipropylene glycol, 1,4-cyclohexanediol, 1 , Polycarbonate with hydroxyl at the end obtained by reacting polyols such as 4-cyclohexanedimethanol, bisphenol A or hydrogenated bisphenol A with dimethyl carbonate, diphenyl carbonate, ethylene carbonate or phosgene, etc. Ester polyols, etc.

As a bisphenol structural unit, the structural unit derived from bisphenol A, bisphenol F, or bisphenol S is mentioned, for example. As a method of introducing a bisphenol structural unit into a cationic urethane resin (A), the method of producing a cationic urethane resin (A) using a polyol having a bisphenol structure is exemplified.

Examples of polyols having a bisphenol structure include polyols obtained by adding alkylene oxide to p-bisphenol A type, bisphenol F type, bisphenol E type, and bisphenol A type; Polyol obtained by adding phenol F type to alkylene oxide; polyol obtained by adding alkylene oxide to bisphenol E type; adding alkylene oxide to hydrogenated bisphenol A type, hydrogenated bisphenol F type and hydrogenated bisphenol A type The polyol obtained by adding hydrogenated bisphenol F type to alkylene oxide, etc.; the polyol obtained by adding hydrogenated bisphenol E type to alkylene oxide.

The cationic polyurethane resin (A) may have structural units other than the above-mentioned polycarbonate structural unit and bisphenol structural unit.

For example, other polyols other than polycarbonate polyols, such as polyether polyols and polyester polyols, can be used together in the production of the cationic polyurethane resin (A).

Furthermore, when producing the cationic polyurethane resin (A), an alcohol compound having a cationic functional group such as a (substituted) amino group (preferably a polyol compound having a cationic functional group such as a (substituted) amino group) (for example, N- methyldiethanolamine, N,N-dimethylaminodimethylolpropane, etc.), or an amine compound having a predetermined cationic functional group, to introduce a desired cationic functional group into the polyurethane resin.

And as mentioned above, when manufacturing a cationic polyurethane resin (A), it is obtained by making the said polyol react with a polyisocyanate (for example, aliphatic, alicyclic, or aromatic polyisocyanate).

As the polyether polyol, polyethylene glycol such as diethylene glycol and triethylene glycol, polyethylene/propylene glycol, and the like can be exemplified.

Examples of polyester polyols include alkylene glycol (eg, carbon number 1 to 6) glycols (ethylene glycol, propylene glycol, butylene glycol, neopentyl glycol, hexylene glycol, etc.), polyether polyols , bisphenol A, hydrogenated bisphenol A, trimethylolpropane or glycerol and other polyols with succinic acid, glutaric acid, adipic acid, sebacic acid, phthalic acid, isophthalic acid, terephthalic acid Polyester polyol etc. which have a hydroxyl group at the terminal obtained by polycondensation of polybasic acid, such as formic acid and trimellitic acid.

As aliphatic, alicyclic or aromatic polyisocyanate, there may be exemplified: toluene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, dicyclohexylmethane diisocyanate, cyclohexylidene diisocyanate, hexamethylene diisocyanate Methyl diisocyanate, lysine diisocyanate, etc.

(Amine value)

The amine value of the cationic polyurethane resin (A) is not particularly limited, but is preferably 2.0 to 5.0 mgKOH/g, more preferably 2.3 to 4.5 mgKOH/g, and still more preferably 2.5 to 2.5 mgKOH/g in terms of more excellent storage stability of the coating material. 4.0 mgKOH/g.

The said amine value is the value measured by the following measuring method, and is defined as a total amine value.

The cationic polyurethane resin (A) of about 3 g in terms of solid content was collected and accurately weighed. Then, dimethylformamide was added and dissolved. Next, several drops of bromocresol green indicator were added, and titration was performed with a 0.1 mol/L hydrochloric acid titration solution, and the amount of the titration solution was read at the point where the change from blue to yellow was used as the end point. The total amine value (mgKOH/g) was calculated according to the following calculation formula.

Total amine value=[(F1-F2)×f×5.611/S]

where:

F1: The amount of 0.1mol/L hydrochloric acid titration solution required for this test (mL);

F2: The amount of 0.1mol/L hydrochloric acid titration solution required for the blank test (mL);

f: titer of 0.1mol/L hydrochloric acid titration solution;

S: Sample collection amount (g).

In addition, the said blank test means the test which measured using deionized water rather than a cationic polyurethane resin.

<Other optional ingredients>

The coating material of this invention may contain other components other than the said cationic urethane resin (A). Hereinafter, optional components will be described in detail.

(phosphoric acid compound (B))

The phosphoric acid compound (B) may be contained in the coating material of the present invention. By including the phosphoric acid compound (B), the corrosion resistance is further improved.

As a phosphoric acid compound (B), at least 1 sort(s) chosen from inorganic phosphoric acid, an inorganic phosphate, an organic phosphoric acid, and an organic phosphate is mentioned, for example.

Examples of inorganic phosphoric acid and salts thereof include monophosphoric acids such as phosphoric acid (orthophosphoric acid), phosphorous acid, triphosphoric acid, hypophosphorous acid, and hypophosphorous acid, derivatives and salts of monophosphoric acid, metaphosphoric acid, tripolyphosphoric acid, tetraphosphoric acid, etc. Condensed phosphoric acid such as phosphoric acid and hexaphosphoric acid, derivatives and salts of condensed phosphoric acid, etc.

Examples of organic phosphoric acid and salts thereof include phosphoric acid monoesters (for example, dihydrogen monododecyl phosphate, dihydrogen monotridecyl phosphate, etc.) and salts thereof, phosphoric acid diesters (for example, hydrogen phosphate Di-dodecyl ester, di-tridecyl hydrogen phosphate, etc.) and salts thereof, etc. Specific examples of organic phosphoric acid include compounds represented by R ₁₀ OP(=O)(OR ₁₁ )(OR ₁₂ ), for example. In addition, R ₁₀ represents an organic group, and R ₁₁ and R ₁₂ each independently represent a hydrogen atom or an organic group. As an organic group, a hydrocarbon group (for example, an alkyl group, an aryl group, or the group which combined these) is mentioned, for example.

In addition, salts, such as inorganic phosphate (salt of inorganic phosphoric acid), organic phosphate (salt of organic phosphoric acid), are not specifically limited, For example, an alkali metal salt, an ammonium salt, and an amine salt are mentioned.

Among them, it is preferable that the phosphoric acid compound (B) contains at least one selected from the group consisting of orthophosphoric acid, condensed phosphoric acid, and salts thereof, from the viewpoint that the effects of the present invention are more excellent.

(Trivalent chromium compound (C))

A trivalent chromium compound (C) may be contained in the coating material of the present invention. By including the trivalent chromium compound (C), the corrosion resistance is further improved.

The trivalent chromium compound (C) refers to a compound capable of supplying trivalent chromium ions, and examples thereof include trivalent chromium salts. Examples of salts include inorganic acid salts such as nitrates, sulfates, and hydrochlorides, and organic acid salts such as acetates, oxalates, and succinates.

Specific examples of the trivalent chromium compound (C) include chromium (III) fluoride, chromium (III) chloride, chromium (III) nitrate, chromium (III) sulfate, chromium (III) acetate, and the like.

(solvent)

A solvent may be included in the coating material of the present invention. As a solvent, water or an organic solvent (for example, alcohol) is mentioned.

(other additives)

The coating material of the present invention may contain a thickener, a leveling agent, a wettability enhancer, an antifoaming agent, a surfactant, a water-soluble alcohol, a cellosolve-based solvent, and the like for the purpose of adjusting coatability.

In addition, a preservative, an antibacterial agent, a coloring agent, an anti-damage agent, a lubricant, etc. may be contained.

In addition, benzotriazoles, guanidine-based compounds, hindered amines, and the like may be contained.

<Coatings for hot-dip galvanized steel sheets>

The above-mentioned various components are contained in the coating material of this invention.

The content of the cationic urethane resin (A) in the coating material is not particularly limited, but is preferably 1 to 40% by mass relative to the total mass of the coating material, and more preferably, from the viewpoint of more excellent effects and handleability of the present invention. 5 to 30 mass %.

When the phosphoric acid compound (B) is contained in the paint, the content of the phosphoric acid compound (B) is not particularly limited, but is preferably 0.1 to 0.1 to 100 parts by mass of the cationic urethane resin (A) from the viewpoint that the effect of the present invention is more excellent. 30 parts by mass, more preferably 0.3 to 25 parts by mass, still more preferably 1 to 10 parts by mass.

When the trivalent chromium compound (C) is contained in the coating material, the content of the trivalent chromium compound (C) is not particularly limited, but it is 100 parts by mass relative to the cationic polyurethane resin (A) from the viewpoint that the effect of the present invention is more excellent. , preferably 0.5 to 20 parts by mass, more preferably 1 to 10 parts by mass.

The preparation method of a coating material is not specifically limited, For example, it can prepare by adding a cationic urethane resin (A) and other optional components to a solvent, such as water, and mixing.

<Manufacturing method of surface-treated hot-dip hot-dip galvanized steel sheet>

The coating material of the present invention can be suitably applied to a hot-dip galvanized steel sheet, and by bringing the coating material of the present invention into contact with a hot-dip galvanized steel sheet, a steel sheet having a hot-dip hot-dip galvanized plated steel sheet and a hot-dip galvanized plated steel sheet can be produced. The surface treatment of the film on the surface is hot-dip hot-dip galvanized steel sheet.

In addition, as mentioned above, the coating material of this invention can also be suitably applied to the zinc-coated steel sheet (or molten zinc-coated steel sheet) containing a hot-dip molten zinc-coated steel sheet.

Hereinafter, the mode of using the hot-dip hot-dip hot-dip hot-dip galvanized steel sheet as the to-be-processed object will typically be described, but it can be applied to a zinc-coated steel sheet other than the hot-dip hot-dip hot-dip hot-dip galvanized steel sheet under the conditions described later. A predetermined coating film is formed, and a surface-treated zinc-based plated steel sheet excellent in various properties is produced. In addition, when the above-mentioned molten zinc plated steel sheet is used, a surface treated molten zinc plated steel sheet having a molten zinc plated steel sheet and a film disposed thereon can also be produced.

The method for producing a surface-treated hot-dip hot-dip galvanized steel sheet using the above-mentioned paint is not particularly limited, but generally includes the following steps: bringing the above-mentioned paint into contact with the hot-dip hot-dip galvanized steel sheet, and heating and drying if necessary. , forming a film on the hot-dip hot-dip galvanized steel sheet to obtain a surface-treated hot-dip hot-dip galvanized steel sheet.

Hereinafter, first, the hot-dip hot-dip galvanized steel sheet as the object to be processed will be described in detail, and then the order of the steps will be described in detail.

(Hot dip galvanized steel sheet)

Hot-dip molten zinc-coated steel sheet refers to a steel sheet obtained by a dipping method in which the steel sheet as the object to be treated is immersed in a molten zinc tank, and the object to be treated is directly and slowly pulled from the plating tank, This implements plating. It should be noted that, as described above, in the hot-dip plating method, the control of the adhesion amount of zinc by an air knife or the like performed in the CGL is not performed, but the object to be treated is pulled from the plating tank and left as it is (cooled). ).

There is no particular limitation on the type of steel sheet to be hot-dip galvanized, and examples thereof include H-beams, guard rails, corrugated pipes, pillars and beams for buildings, pillars for sound insulation walls, sign pillars, lighting pillars, large Zinc plating is applied to bridges such as truss bridges and flyover bridges, iron bars, wire harnesses of power towers, etc., small parts such as bolts and nuts, mounts for solar cells or small wind power generators, outdoor exposed iron frames, etc. All construction materials processed can also be cut-to-plate or coil-shaped steel.

It should be noted that when oil, dirt, etc. adhere to the surface of the hot-dip molten zinc-coated steel sheet, it is preferable to wash with an alkali degreaser, neutral degreaser, or acid degreaser, etc., and then perform hot water washing or water washing to improve the surface state. clean.

(Contact method of paint)

The method of contacting the coating material with the hot-dip hot-dip galvanized steel sheet is not particularly limited, and examples thereof include dipping, spraying, brush coating, electrostatic coating, and the like in the cooling step after plating. In addition, when the hot-dip molten zinc-coated steel sheet is in the form of a coil, a conventionally used method can be applied, for example, roll coating, shower wringer roll, spray treatment, dipping treatment, curtain Coating, flow coating, spin coating, etc.

(Drying method of paint)

As a drying method of the paint, the most economical method is a method using preheating after the plating process, and the hot-dip molten zinc plated steel sheet can be dipped in the paint and left as it is to dry. In addition, at the time of drying, the wind for blowing off the water|moisture content adhering to the surface of a hot-dip hot-dip galvanized steel sheet efficiently may be blown.

In the processing step, when it is difficult to use the preheating after the zinc plating process, it is preferable to use a drying device that can evaporate the water contained in the paint. The type of drying equipment in this case is not particularly limited, and examples thereof include hot air drying equipment, induction heating drying equipment, infrared heating drying equipment, near-infrared heating drying equipment, and the like. The drying temperature when these drying facilities are used is not particularly limited, but the limit temperature of the surface of the hot-dip hot-dip galvanized steel sheet is preferably 60°C to 200°C, and more preferably 80°C to 180°C.

(coating film adhesion amount)

By carrying out the said process, the surface-treated hot-dip hot-dip hot-dip zinc-coated steel sheet which has a hot-dip hot-dip hot-dip hot-dip zinc-coated steel sheet and a film arranged on the surface is produced.

The adhesion amount of the film is not particularly limited, but is preferably 0.3 to 5.0 g/m ² , and more preferably 0.5 to 3.0 g/m ² , because the effect of the present invention is more excellent.

The produced surface-treated hot-dip hot-dip molten zinc-coated steel sheet can be suitably used for various applications, and examples thereof include parts for household appliances and building materials.

Moreover, you may apply coating to the surface-treated hot-dip molten zinc-coated steel sheet of the present invention. In this case, some kind of processing may be further performed on the painted plate.

Example

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples of the present invention, but the present invention is not limited to these Examples.

1. Test material

The test materials (raw materials) used are described below. Usually, the hot-dip galvanized product is a shaped object in many cases, but in this test, a plate was used as a raw material. It should be noted that even if the shape of the raw material is changed, the effect exhibited by the present invention will not be affected at all.

The molten zinc-coated steel sheet represented by M1 below corresponds to the hot-dip molten zinc-coated steel sheet produced by the above-described hot-dip plating. In addition, M1 - M3 correspond to molten zinc-coated steel sheets (in addition, M2 and M3 do not correspond to hot-dip molten zinc-coated steel sheets).

M1: Hot-dip galvanized steel sheet (according to JIS H 8641 HDZ35), small spangle, size: 700mm×150mm×1.6mm (plate thickness), double-sided plating adhesion amount: 360g/m ²

M2: Hot-dip galvanized steel sheet (according to JIS G 3302 SGCC Z06), size: 700mm x 150mm x 0.8mm (plate thickness), double-sided plating adhesion amount: 60g/m ²

M3: molten zinc-5% aluminum alloy plated steel sheet (according to JIS G 3317 SZACCY08), size: 700mm×150mm×0.8mm (plate thickness), double-sided plating adhesion amount: 80g/m ²

2. Pretreatment (degreasing treatment)

Using Fine Cleaner E6406 (manufactured by Japan Parkerizing Co., Ltd.) of a silicate-based alkaline degreasing agent, the above-mentioned test material was sprayed for 10 seconds under the conditions of a concentration of 20 g/L and a temperature of 60° C., and further purified water was used. After washing with water for 30 seconds, the obtained dried product was used for the following test.

3. Paint

In Table 1, the details of the cationic urethane resin (A) used are shown. In addition, the manufacturing method is demonstrated in detail in the latter stage.

The loss modulus E″ and loss tangent tan δ of the cationic urethane resin (A) were measured in the following procedure. First, the film (thickness: 300 to 500 μm) of the cationic polyurethane resin (A) was left at room temperature for 15 hours, then dried at 80° C. for 6 hours, and further dried at 120° C. for 20 minutes.

Next, using the dynamic viscoelasticity measuring apparatus "RSAG2" manufactured by TA Instruments, the transverse direction (TD) of the obtained film (sample area: grip length × width = 20 mm × 5 mm) was subjected to vibration frequency of 10 Hz and strain of 0.1%. , measured from -100°C to 200°C at a heating rate of 5°C/min, and calculated storage modulus E', loss modulus E'', and loss tangent tan δ . In addition, the distance between jigs (chucks) was set to 10 mm.

The measuring method of the amine value is as follows.

In Table 1, Tg1 represents the temperature of the maximum peak of the loss modulus E″ obtained by the above measurement, and Tg2 represents the peak temperature of the loss tangent tan δ obtained by the above measurement.

In addition, the number of peaks refers to the number of peaks in the temperature dependence curve of loss tangent tan δ , which is the ratio of loss modulus E'' to storage modulus E'.

[Table 1]

(Production Example 1: Cationic Polyurethane Resin (A1))

Into a four-necked flask equipped with a stirrer, a reflux cooling tube, a thermometer, and a nitrogen gas injection tube, 1,000 parts by mass of polycarbonate polyol (Nippollan 981R, manufactured by Tosoh Corporation, Mw=2,000), bisphenol A-bis( Hydroxyethyl ether) (BPE20T, manufactured by Sanyo Chemical Co., Ltd., hydroxyl value 346 mg/g) 100 parts by mass, 100 parts by mass of N-methyldiethanolamine, 400 parts by mass of hexamethylene diisocyanate, methyl ethyl ketone 800 mass parts were made to react at 75 degreeC for 4 hours, and the methyl ethyl ketone solution of the urethane prepolymer whose content of the free isocyanate group with respect to a nonvolatile matter was 3.0 mass % was obtained. The solution was cooled to 40° C., 103 parts by mass of dimethyl sulfate was added, and then 2,700 parts by mass of deionized water was gradually added to emulsify and disperse the solution. Then, an aqueous solution obtained by dissolving 45 parts by mass of ethylenediamine in 100 g of water was added, and stirring was continued for 1 hour. This was desolvated at 50 degreeC under reduced pressure, and the polyurethane water dispersion 1 containing the cationic polyurethane resin (A1) of about 35 mass % of nonvolatile components was obtained.

(Production Example 2: Cationic Polyurethane Resin (A2))

Into a four-necked flask equipped with a stirrer, a reflux cooling tube, a thermometer, and a nitrogen gas injection tube, 1500 parts by mass of polycarbonate polyol (Nippollan 981R, manufactured by Tosoh Corporation, Mw=2,000), bisphenol A-bis( Hydroxyethyl ether) (BPE20T, manufactured by Sanyo Chemical Co., Ltd., hydroxyl value 346 mg/g) 50 parts by mass, 50 parts by mass of N-methyldiethanolamine, 325 parts by mass of hexamethylene diisocyanate, methyl ethyl ketone 800 mass parts were made to react at 75 degreeC for 4 hours, and the methyl ethyl ketone solution of the urethane prepolymer whose content of the free isocyanate group with respect to a nonvolatile matter was 3.0 mass % was obtained. The solution was cooled to 40° C., and 47 parts by mass of dimethyl sulfate was added, and then 2,700 parts by mass of deionized water was gradually added and emulsified and dispersed. Then, an aqueous solution obtained by dissolving 45 parts by mass of ethylenediamine in 100 g of water was added, and stirring was continued for 1 hour. This was desolvated at 50 degreeC under reduced pressure, and the polyurethane water dispersion 2 containing the cationic polyurethane resin (A2) of about 35 mass % of nonvolatile components was obtained.

(Production Example 3: Cationic Polyurethane Resin (A3))

To a four-necked flask equipped with a stirrer, a reflux cooling tube, a thermometer, and a nitrogen gas injection tube, 1,000 parts by mass of polycarbonate polyol (Nippollan 980, manufactured by Tosoh Corporation, Mw=1,000), bisphenol A-bis(hydroxyl) Ethyl ether) (BPE20T, manufactured by Sanyo Chemical Co., Ltd., hydroxyl value 346 mg/g) 300 parts by mass, 100 parts by mass of N-methyldiethanolamine, 535 parts by mass of hexamethylene diisocyanate, dicyclohexylmethane diisocyanate 250 parts by mass and 800 parts by mass of methyl ethyl ketone were reacted at 75° C. for 4 hours to obtain a methyl methacrylate of a urethane prepolymer having a content of free isocyanate groups relative to nonvolatile components of 3.0% by mass. ethyl ketone solution. The solution was cooled to 40° C., and 95 parts by mass of dimethyl sulfate was added, and then 2,700 parts by mass of deionized water was gradually added and emulsified and dispersed. Then, an aqueous solution obtained by dissolving 45 parts by mass of ethylenediamine in 100 g of water was added, and stirring was continued for 1 hour. This was desolvated at 50 degreeC under reduced pressure, and the polyurethane water dispersion 3 containing the cationic polyurethane resin (A3) of about 35 mass % of nonvolatile components was obtained.

(Production Example 4: Cationic Polyurethane Resin (A4))

Into a four-necked flask equipped with a stirrer, a reflux cooling tube, a thermometer, and a nitrogen gas injection tube, 1,000 parts by mass of polycarbonate polyol (Nippollan 981R, manufactured by Tosoh Corporation, Mw=2,000), bisphenol A-bis( Hydroxyethyl ether) (BPE20T, manufactured by Sanyo Chemical Co., Ltd., hydroxyl value 346 mg/g) 200 parts by mass, 100 parts by mass of N-methyldiethanolamine, 480 parts by mass of hexamethylene diisocyanate, methyl ethyl ketone 800 mass parts were made to react at 75 degreeC for 4 hours, and the methyl ethyl ketone solution of the urethane prepolymer whose content of the free isocyanate group with respect to a nonvolatile matter was 3.0 mass % was obtained. The solution was cooled to 40° C., and 101 parts by mass of dimethyl sulfate was added, and then 2,700 parts by mass of deionized water was gradually added and emulsified and dispersed. Then, an aqueous solution obtained by dissolving 45 parts by mass of ethylenediamine in 100 g of water was added, and stirring was continued for 1 hour. This was desolvated at 50 degreeC under reduced pressure, and the polyurethane water dispersion 4 containing the cationic polyurethane resin (A4) of about 35 mass % of nonvolatile components was obtained.

(Production Example 5: Cationic Polyurethane Resin (A5))

Into a four-necked flask equipped with a stirrer, a reflux cooling tube, a thermometer, and a nitrogen gas injection tube, 1500 parts by mass of polycarbonate polyol (Nippollan 981R, manufactured by Tosoh Corporation, Mw=2,000), bisphenol A-bis( Hydroxyethyl ether) (BPE20T, manufactured by Sanyo Chemical Co., Ltd., hydroxyl value 346 mg/g) 100 parts by mass, 50 parts by mass of N-methyldiethanolamine, 370 parts by mass of hexamethylene diisocyanate, methyl ethyl ketone 800 mass parts were made to react at 75 degreeC for 4 hours, and the methyl ethyl ketone solution of the urethane prepolymer whose content of the free isocyanate group with respect to a nonvolatile matter was 3.0 mass % was obtained. The solution was cooled to 40° C., and 48 parts by mass of dimethyl sulfate was added, and then 2,700 parts by mass of deionized water was gradually added and emulsified and dispersed. Then, an aqueous solution obtained by dissolving 45 parts by mass of ethylenediamine in 100 g of water was added, and stirring was continued for 1 hour. This was desolvated at 50 degreeC under reduced pressure, and the polyurethane water dispersion 5 containing the cationic polyurethane resin (A5) of about 35 mass % of nonvolatile components was obtained.

(Production Example 6: Cationic Polyurethane Resin (A6))

To a four-necked flask equipped with a stirrer, a reflux cooling tube, a thermometer, and a nitrogen gas injection tube, 1,000 parts by mass of polycarbonate polyol (Nippollan 980, manufactured by Tosoh Corporation, Mw=1,000), bisphenol A-bis(hydroxyl) Ethyl ether) (BPE20T, manufactured by Sanyo Chemical Co., Ltd., hydroxyl value 346 mg/g) 200 parts by mass, 100 parts by mass of N-methyldiethanolamine, 450 parts by mass of hexamethylene diisocyanate, dicyclohexylmethane diisocyanate 220 parts by mass and 800 parts by mass of methyl ethyl ketone were reacted at 75° C. for 4 hours to obtain a methyl methacrylate of a urethane prepolymer with a content of free isocyanate groups relative to nonvolatile components of 3.0% by mass. ethyl ketone solution. The solution was cooled to 40° C., and 87 parts by mass of dimethyl sulfate was added, and then 2,700 parts by mass of deionized water was gradually added and emulsified and dispersed. Then, an aqueous solution obtained by dissolving 45 parts by mass of ethylenediamine in 100 g of water was added, and stirring was continued for 1 hour. This was desolvated at 50 degreeC under reduced pressure, and the polyurethane water dispersion 6 containing the cationic polyurethane resin (A6) of about 35 mass % of nonvolatile components was obtained.

(Production Example 7: Cationic Polyurethane Resin (A7))

Into a four-necked flask equipped with a stirrer, a reflux cooling tube, a thermometer, and a nitrogen gas injection tube, 1500 parts by mass of polycarbonate polyol (Nippollan 981R, manufactured by Tosoh Corporation, Mw=2,000), bisphenol A-bis( Hydroxyethyl ether) (BPE20T, manufactured by Sanyo Chemical Co., Ltd., hydroxyl value 346 mg/g) 100 parts by mass, 50 parts by mass of N-methyldiethanolamine, 260 parts by mass of hexamethylene diisocyanate, dicyclohexylmethanedi 150 parts by mass of isocyanate and 800 parts by mass of methyl ethyl ketone were reacted at 75° C. for 4 hours to obtain a urethane prepolymer having a content of free isocyanate groups of 3.0 mass % relative to the nonvolatile matter. Methyl ethyl ketone solution. The solution was cooled to 40° C., and 49 parts by mass of dimethyl sulfate was added, and then 2,700 parts by mass of deionized water was gradually added and emulsified and dispersed. Then, an aqueous solution obtained by dissolving 45 parts by mass of ethylenediamine in 100 g of water was added, and stirring was continued for 1 hour. This was desolvated at 50 degreeC under reduced pressure, and the polyurethane water dispersion 7 containing the cationic polyurethane resin (A7) of about 35 mass % of nonvolatile components was obtained.

(Production Example 8: Cationic Polyurethane Resin (A8))

Into a four-necked flask equipped with a stirrer, a reflux cooling tube, a thermometer, and a nitrogen gas injection tube, 1500 parts by mass of polycarbonate polyol (Nippollan 981R, manufactured by Tosoh Corporation, Mw=2,000), bisphenol A-bis( Hydroxyethyl ether) (BPE20T, manufactured by Sanyo Chemical Co., Ltd., hydroxyl value 346 mg/g) 100 parts by mass, 50 parts by mass of N-methyldiethanolamine, 315 parts by mass of hexamethylene diisocyanate, dicyclohexylmethanedi 80 parts by mass of isocyanate and 800 parts by mass of methyl ethyl ketone were reacted at 75° C. for 4 hours to obtain a urethane prepolymer having a content of free isocyanate groups of 3.0% by mass relative to the nonvolatile content. Methyl ethyl ketone solution. The solution was cooled to 40° C., and 49 parts by mass of dimethyl sulfate was added, and then 2,700 parts by mass of deionized water was gradually added and emulsified and dispersed. Then, an aqueous solution obtained by dissolving 45 parts by mass of ethylenediamine in 100 g of water was added, and stirring was continued for 1 hour. This was desolvated at 50 degreeC under reduced pressure, and the polyurethane water dispersion 8 containing the cationic polyurethane resin (A8) of about 35 mass % of nonvolatile components was obtained.

(Production Example 9: Cationic Polyurethane Resin (A9))

Into a four-necked flask equipped with a stirrer, a reflux cooling tube, a thermometer, and a nitrogen gas injection tube, 1500 parts by mass of polycarbonate polyol (Nippollan 981R, manufactured by Tosoh Corporation, Mw=2,000), bisphenol A-bis( Hydroxyethyl ether) (BPE20T, manufactured by Sanyo Chemical Co., Ltd., hydroxyl value 346 mg/g) 50 parts by mass, 50 parts by mass of N-methyldiethanolamine, 310 parts by mass of hexamethylene diisocyanate, dicyclohexylmethanedi 35 parts by mass of isocyanate and 800 parts by mass of methyl ethyl ketone were reacted at 75° C. for 4 hours to obtain a urethane prepolymer having a content of free isocyanate groups of 3.0% by mass relative to the nonvolatile content. Methyl ethyl ketone solution. The solution was cooled to 40° C., and 49 parts by mass of dimethyl sulfate was added, and then 2,700 parts by mass of deionized water was gradually added and emulsified and dispersed. Then, an aqueous solution obtained by dissolving 45 parts by mass of ethylenediamine in 100 g of water was added, and stirring was continued for 1 hour. This was desolvated at 50 degreeC under reduced pressure, and the polyurethane water dispersion 9 containing the cationic polyurethane resin (A9) of about 35 mass % of nonvolatile components was obtained.

(Production Example 10: Cationic Polyurethane Resin (A10))

750 parts by mass of polycarbonate polyol (Nippollan 981R, manufactured by Tosoh Co., Ltd., Mw=2,000), bisphenol A-bis( Hydroxyethyl ether) (BPE20T, manufactured by Sanyo Chemical Co., Ltd., hydroxyl value 346 mg/g) 125 parts by mass, 50 parts by mass of N-methyldiethanolamine, 290 parts by mass of hexamethylene diisocyanate, dicyclohexylmethanedi 35 parts by mass of isocyanate and 800 parts by mass of methyl ethyl ketone were reacted at 75° C. for 4 hours to obtain a urethane prepolymer having a content of free isocyanate groups of 3.0% by mass relative to the nonvolatile content. Methyl ethyl ketone solution. The solution was cooled to 40° C., and 51 parts by mass of dimethyl sulfate was added, and then 2,700 parts by mass of deionized water was gradually added and emulsified and dispersed. Then, an aqueous solution obtained by dissolving 45 parts by mass of ethylenediamine in 100 g of water was added, and stirring was continued for 1 hour. This was desolvated at 50 degreeC under reduced pressure, and the polyurethane water dispersion 10 containing the cationic polyurethane resin (A10) of about 35 mass % of nonvolatile components was obtained.

(Production Example 11: Cationic Polyurethane Resin (A11))

750 parts by mass of polycarbonate polyol (Nippollan 981R, manufactured by Tosoh Co., Ltd., Mw=2,000), bisphenol A-bis( Hydroxyethyl ether) (BPE20T, manufactured by Sanyo Chemical Co., Ltd., hydroxyl value 346 mg/g) 125 parts by mass, 50 parts by mass of N-methyldiethanolamine, 220 parts by mass of hexamethylene diisocyanate, dicyclohexylmethanedi 110 parts by mass of isocyanate and 800 parts by mass of methyl ethyl ketone were reacted at 75° C. for 4 hours to obtain a urethane prepolymer having a content of free isocyanate groups of 3.0 mass % relative to the nonvolatile matter. Methyl ethyl ketone solution. The solution was cooled to 40° C., 50 parts by mass of dimethyl sulfate was added, and then 2,700 parts by mass of deionized water was gradually added to emulsify and disperse the solution. Then, an aqueous solution obtained by dissolving 45 parts by mass of ethylenediamine in 100 g of water was added, and stirring was continued for 1 hour. This was desolvated at 50 degreeC under reduced pressure, and the polyurethane water dispersion 11 containing the cationic polyurethane resin (A11) of about 35 mass % of nonvolatile components was obtained.

(Production Example 12: Cationic Polyurethane Resin (A12))

Into a four-necked flask equipped with a stirrer, a reflux cooling tube, a thermometer, and a nitrogen gas injection tube, 500 parts by mass of polycarbonate polyol (Nippollan 980, manufactured by Tosoh Co., Ltd., Mw=1,000), polycarbonate polyol (Nippollan 981R) , manufactured by Tosoh Co., Ltd., Mw=2,000) 250 parts by mass, bisphenol A-bis(hydroxyethyl ether) (BPE20T, manufactured by Sanyo Chemical Co., Ltd., hydroxyl value 346 mg/g) 150 parts by mass, N-methyl 50 parts by mass of diethanolamine, 275 parts by mass of hexamethylene diisocyanate, 150 parts by mass of dicyclohexylmethane diisocyanate, and 800 parts by mass of methyl ethyl ketone were reacted at 75° C. for 4 hours to obtain free A methyl ethyl ketone solution of a urethane prepolymer having an isocyanate group content of 3.0 mass % with respect to the nonvolatile content. The solution was cooled to 40° C., and 44 parts by mass of dimethyl sulfate was added, and then 2,700 parts by mass of deionized water was gradually added and emulsified and dispersed. Then, an aqueous solution obtained by dissolving 45 parts by mass of ethylenediamine in 100 g of water was added, and stirring was continued for 1 hour. This was desolvated at 50 degreeC under reduced pressure, and the polyurethane water dispersion 12 containing the cationic polyurethane resin (A12) of about 35 mass % of nonvolatile components was obtained.

(Production Example 13: Cationic Polyurethane Resin (A13))

Into a four-necked flask equipped with a stirrer, a reflux cooling tube, a thermometer, and a nitrogen gas injection tube, 1500 parts by mass of polycarbonate polyol (Nippollan 980, manufactured by Tosoh Corporation, Mw=1,000), bisphenol A-bis(hydroxyl) Ethyl ether) (BPE20T, manufactured by Sanyo Chemical Co., Ltd., hydroxyl value 346 mg/g) 25 parts by mass, 50 parts by mass of N-methyldiethanolamine, 500 parts by mass of hexamethylene diisocyanate, 800 parts by mass of methyl ethyl ketone part by mass, it was made to react at 75 degreeC for 4 hours, and the methyl ethyl ketone solution of the urethane prepolymer whose content of the free isocyanate group with respect to a nonvolatile matter was 3.0 mass % was obtained. The solution was cooled to 40° C., and 49 parts by mass of dimethyl sulfate was added, and then 2,700 parts by mass of deionized water was gradually added and emulsified and dispersed. Then, an aqueous solution obtained by dissolving 45 parts by mass of ethylenediamine in 100 g of water was added, and stirring was continued for 1 hour. This was desolventized at 50 degreeC under reduced pressure, and the polyurethane water dispersion 13 containing the cationic polyurethane resin (A13) of about 35 mass % of nonvolatile components was obtained.

(Production Example 14: Cationic Polyurethane Resin (A14))

Into a four-necked flask equipped with a stirrer, a reflux cooling tube, a thermometer, and a nitrogen gas injection tube, 1500 parts by mass of polycarbonate polyol (Nippollan 980, manufactured by Tosoh Corporation, Mw=1,000), bisphenol A-bis(hydroxyl) Ethyl ether) (BPE20T, manufactured by Sanyo Chemical Co., Ltd., hydroxyl value 346 mg/g) 25 parts by mass, 50 parts by mass of N-methyldiethanolamine, 500 parts by mass of hexamethylene diisocyanate, 800 parts by mass of methyl ethyl ketone part by mass, it was made to react at 75 degreeC for 4 hours, and the methyl ethyl ketone solution of the urethane prepolymer whose content of the free isocyanate group with respect to a nonvolatile matter was 3.0 mass % was obtained. The solution was cooled to 40° C., 25 parts by mass of dimethyl sulfate was added, and then 2,700 parts by mass of deionized water was gradually added and emulsified and dispersed. Then, an aqueous solution obtained by dissolving 45 parts by mass of ethylenediamine in 100 g of water was added, and stirring was continued for 1 hour. This was desolvated at 50 degreeC under reduced pressure, and the polyurethane water dispersion 14 containing the cationic polyurethane resin (A14) of about 35 mass % of nonvolatile components was obtained.

(Production Example 15: Cationic Polyurethane Resin (A15))

Into a four-necked flask equipped with a stirrer, a reflux cooling tube, a thermometer, and a nitrogen gas injection tube, 1,600 parts by mass of polycarbonate polyol (Nippollan 981R, manufactured by Tosoh Corporation, Mw=2,000), bisphenol A-bis( Hydroxyethyl ether) (BPE20T, manufactured by Sanyo Chemical Co., Ltd., hydroxyl value 346 mg/g) 150 parts by mass, 50 parts by mass of N-methyldiethanolamine, 245 parts by mass of hexamethylene diisocyanate, dicyclohexylmethanedi 275 parts by mass of isocyanate and 800 parts by mass of methyl ethyl ketone were reacted at 75° C. for 4 hours to obtain a urethane prepolymer having a content of free isocyanate groups relative to nonvolatile components of 3.0% by mass. Methyl ethyl ketone solution. The solution was cooled to 40° C., and 48 parts by mass of dimethyl sulfate was added, and then 2,700 parts by mass of deionized water was gradually added and emulsified and dispersed. Then, an aqueous solution obtained by dissolving 45 parts by mass of ethylenediamine in 100 g of water was added, and stirring was continued for 1 hour. This was desolvated at 50 degreeC under reduced pressure, and the polyurethane water dispersion 15 containing the cationic polyurethane resin (A15) of about 35 mass % of nonvolatile components was obtained.

(Production Example 16: Cationic Polyurethane Resin (A16))

To a four-necked flask equipped with a stirrer, a reflux cooling tube, a thermometer, and a nitrogen gas injection tube, 600 parts by mass of polycarbonate polyol (Nippollan 981R, manufactured by Tosoh Co., Ltd., Mw=2,000), bisphenol A-bis( Hydroxyethyl ether) (BPE20T, manufactured by Sanyo Chemical Co., Ltd., hydroxyl value 346 mg/g) 50 parts by mass, 175 parts by mass of N-methyldiethanolamine, 550 parts by mass of hexamethylene diisocyanate, methyl ethyl ketone 800 mass parts were made to react at 75 degreeC for 4 hours, and the methyl ethyl ketone solution of the urethane prepolymer whose content of the free isocyanate group with respect to a nonvolatile matter was 3.0 mass % was obtained. The solution was cooled to 40° C., and 179 parts by mass of dimethyl sulfate was added, and then 2,700 parts by mass of deionized water was gradually added and emulsified and dispersed. Then, an aqueous solution obtained by dissolving 45 parts by mass of ethylenediamine in 100 g of water was added, and stirring was continued for 1 hour. This was desolvated at 50 degreeC under reduced pressure, and the polyurethane water dispersion 16 containing the cationic polyurethane resin (A16) of about 35 mass % of nonvolatile components was obtained.

(Production Example 17: Cationic Polyurethane Resin (A17))

To a four-necked flask equipped with a stirrer, a reflux cooling tube, a thermometer, and a nitrogen gas injection tube, 1,000 parts by mass of polycarbonate polyol (Kuraray Polyol C-3090, manufactured by Kuraray Co., Ltd., Mw=3,000), bisphenol A-bis(hydroxyethyl ether) (BPE20T, manufactured by Sanyo Chemical Co., Ltd., hydroxyl value 346 mg/g) 20 parts by mass, 30 parts by mass of N-methyldiethanolamine, 160 parts by mass of hexamethylene diisocyanate, methyl 800 parts by mass of methyl ethyl ketone was reacted at 75° C. for 4 hours to obtain a methyl ethyl ketone solution of a urethane prepolymer having a content of free isocyanate groups with respect to non-volatile components of 3.0% by mass . The solution was cooled to 40° C., 30 parts by mass of dimethyl sulfate was added, and then 2,700 parts by mass of deionized water was gradually added to emulsify and disperse the solution. Then, an aqueous solution obtained by dissolving 45 parts by mass of ethylenediamine in 100 g of water was added, and stirring was continued for 1 hour. This was desolvated at 50 degreeC under reduced pressure, and the polyurethane water dispersion 17 containing the cationic polyurethane resin (A17) of about 35 mass % of nonvolatile components was obtained.

(Production Example 18: Cationic Polyurethane Resin (A18))

Into a four-necked flask equipped with a stirrer, a reflux cooling tube, a thermometer, and a nitrogen gas injection tube, 600 parts by mass of polyethylene glycol (PEG2000, manufactured by Sanyo Chemical Co., Ltd., Mw=2,000) and 30 mass parts of N-methyldiethanolamine were added parts, 80 parts by mass of hexamethylene diisocyanate, and 800 parts by mass of methyl ethyl ketone, and reacted at 75° C. for 4 hours to obtain an amino group having a free isocyanate group content of 3.0 mass % with respect to the nonvolatile content. A solution of formate prepolymer in methyl ethyl ketone. The solution was cooled to 40° C., 30.2 parts by mass of dimethyl sulfate was added, and then 2,700 parts by mass of deionized water was gradually added to emulsify and disperse the solution. Then, an aqueous solution obtained by dissolving 45 parts by mass of ethylenediamine in 100 g of water was added, and stirring was continued for 1 hour. This was desolvated at 50 degreeC under reduced pressure, and the polyurethane water dispersion 18 containing the cationic polyurethane resin (A18) of about 35 mass % of nonvolatile components was obtained.

The phosphoric acid compound (B) used is shown in Table 2, and the trivalent chromium compound (C) used is shown in Table 3.

[Table 2]

Table 2 label Element B1 Phosphoric acid B2 metaphosphoric acid

[table 3]

table 3 label Element C1 Chromium Fluoride

4. Preparation of paint

The cationic polyurethane resin (A), the phosphoric acid compound (B), and the trivalent chromium compound (C) were sequentially mixed in the combinations and ratios shown in Table 4, and the solid content concentration was adjusted to 20% by mass with deionized water. Paint is prepared. In addition, the content ratio of the phosphoric acid compound (B) and the trivalent chromium compound (C) is the mass % with respect to the solid content of the cationic urethane resin (A) (in other words, it refers to the content of each component with respect to the cationic urethane resin). (A) 100 parts by mass of content (parts by mass)).

In addition, in Table 4, "BV/AV" represents the ratio of the content ratio (mass %) (BV) of the phosphoric acid compound (B) to the solid content of the cationic urethane resin (A) and the amine value.

[Table 4]

5. How to make the test board

The coating material of this invention was apply|coated to each test material by a bar coater, and it heat-processed at the limit board temperature shown in Table 5, and formed a film on each test material, and produced the test panel. In addition, the film amount in each example is as shown in Table 5, and adjustment of the film amount was implemented by the concentration adjustment (deionized water dilution) of a coating material, and the serial number of a bar coater.

[table 5]

[Table 6]

[Table 7]

[Table 8]

6. Evaluation method

(1) Appearance characteristics (film appearance)

The appearance of the obtained test panel was visually evaluated. ○Above is the practical level.

◎+: Appearance is roughly the same as that of plating, and there is little change after coating treatment;

◎: Appearance is approximately the same as that of plating, but there may be very little unevenness in color tone depending on the viewing angle;

○: Almost the same as the plating appearance, but there is a very small degree of uneven color tone;

△: There is a part different from the plating appearance, and the part is light white or yellow;

×: There are many parts different from the plating appearance, and it is clearly white or yellow.

(2) Friction resistance (solvent resistance)

Ethanol was impregnated into the gauze, and the surface of the coating film of the obtained test plate was subjected to a rubbing test of reciprocating 20 times, and the surface was observed. △The above is the practical level.

◎+: No change in appearance at all;

◎: No change in appearance (no change from frontal observation), slight change from oblique observation;

○: slightly changed from frontal observation;

△: There is a slight change from the front view (about half peeled off);

×: There is a change (substantially the entire surface is peeled off).

(3) Corrosion resistance

Using the obtained test plate, a salt spray test was performed based on JIS-Z-2371, the area ratio of white rust generation after 24 hours was determined, and the evaluation was performed according to the following criteria. △The above is the practical level. Of these, regarding the examples and comparative examples using the test material M3, the area ratio of white rust generation after 48 hours of the salt spray test was determined, and the evaluation was performed according to the following criteria.

◎+: less than 5%;

◎: 5% or more and less than 10%;

○+: 10% or more and less than 20%;

○: 20% or more and less than 30%;

△+: more than 30% and less than 40%;

△: 40% or more and less than 50%;

×: 50% or more.

(4) Phosphating property (coating type phosphate treating property)

The obtained test panel was treated with Palbond L 15C (A agent 250 g/L + B agent 250 g/L, 25°C, brush coating), a chemical synthesis agent for phosphate treatment manufactured by Parkerizing Co., Ltd., Japan, and then left for 5 minutes. , the surface state of the brush-coated portion was observed, the gray discoloration area ratio of the brush-coated portion was obtained, and the evaluation was performed according to the following criteria. In addition, the higher the gray discoloration area ratio, the more the formed film is partially dissolved by the phosphate treatment, and the more the phosphate film is formed, the more gray tone appears. △The above is the practical level.

◎+: 100%;

◎: 95% or more and less than 100%;

○: 85% or more and less than 95%;

△: 70% or more and less than 85%;

×: Less than 70%.

(5) Surface coating adhesion

On the film of the obtained test panel, a melamine alkyd resin coating material was applied using a bar coater so that the dry film thickness would be 25 μm, and the coating film was produced by baking at an oven temperature of 130° C. for 20 minutes. Next, for the coating film, 100 pieces of grids with a width of 1 mm were formed by a cutting machine, and were allowed to stand for more than 5 hours in a constant temperature chamber at -20°C. Immediately after taking out from the constant temperature chamber, the parts of the grids were extruded by 7 mm. Erichsen processing. The tape peeling test of the processed part was implemented, and the peeling number of the grid was evaluated as follows. △The above is the practical level.

◎+: no peeling;

◎: The number of peelings is 1 or more and less than 5;

○: The number of peelings is 6 or more and less than 10;

△: The number of peelings is 11 or more and less than 20;

×: The number of peeled objects is 20 or more.

(6) Impact resistance

On the film of the obtained test panel, a melamine alkyd resin coating material was applied using a bar coater so that the dry film thickness would be 25 μm, and the coating film was produced by baking at an oven temperature of 130° C. for 20 minutes. Next, the test panel with the coating film was placed in a constant temperature chamber at 40°C for more than 5 hours, and immediately after taking out the test panel, a DuPont impact tester was used to make a 1/2 inch diameter, 1 kg After the plumb bob (vertical weight) was dropped from a height of 50 cm, the impact portion was tape-peeled. The determination is to obtain the remaining area ratio of the coating film. △The above is the practical level.

◎+: 100%;

◎: 95% or more and less than 100%;

○: 80% or more and less than 95%;

△: 50% or more and less than 80%;

×: Less than 50%.

(7) Storage stability of coatings

When the paints used in the respective Examples and Comparative Examples were allowed to stand in an environment of 40°C, the storage stability was evaluated as follows until gelation and precipitation occurred. △The above is the practical level.

◎+: more than 3 months;

◎: More than 2 months and less than 3 months;

○: More than 1 month and less than 2 months;

△: More than 2 weeks and less than 1 month;

×: Less than 2 weeks.

[Table 9]

[Table 10]

[Table 11]

[Table 12]

As shown in Table 6, it was confirmed that the desired effect can be obtained by using the coating material of the present invention.

Among them, from the comparison of Examples 2, 5, 12 and 21 with other Examples, it was confirmed that when a phosphoric acid compound was used, the effect was more excellent (in particular, the phosphate treatment property was excellent).

In addition, from the comparison of Example 26 with other examples (for example, Example 25, etc.), it was confirmed that when the peak temperature (Tg2) of the loss tangent tan δ is within the predetermined range (-50°C to -2°C), the surface coating The layer coating adhesion is more excellent.

In addition, from the comparison of Examples 7 to 8 and Examples 12 to 19, it was confirmed that when the ratio ((BV)/(AV)) is within the predetermined range (0.1 to 9.5), the effect is more excellent.

In addition, from the comparison of Example 20 and Examples 27 to 29, it was confirmed that when the amine value (AV) is within the predetermined range (2 to 5 mgKOH/g), the effect is more excellent (in particular, the storage stability is excellent).

In addition, from the comparison of Example 25 and Examples 30 to 32, it was confirmed that by further using the trivalent chromium compound (C), the effect is more excellent (in particular, the corrosion resistance is excellent).

Claims (20)

1. A coating for hot-dip molten zinc-coated steel sheets, comprising a cationic polyurethane resin (A) having at least one cationic functional group selected from primary to tertiary amino groups and quaternary ammonium salt groups, The aforementioned cationic polyurethane resin (A) has a polycarbonate structural unit and a bisphenol structural unit, The temperature (Tg1) at which the maximum peak value of the loss modulus E" of the cationic urethane resin (A) is shown is in the range of -60°C to -5°C, The ratio of the loss modulus E" to the storage modulus E' of the cationic urethane resin (A), that is, the loss tangent tanδ, consists of one peak. 2 . The coating material for hot dip galvanized steel sheet according to claim 1 , wherein the peak temperature (Tg2 ) of the loss tangent tanδ is in the range of -50°C to -2°C. 3 . 3. The coating material for hot-dip galvanized steel sheets according to claim 1, which further contains a phosphoric acid compound (B). 4 . The coating material for hot-dip molten zinc plated steel sheets according to claim 2 , further comprising a phosphoric acid compound (B). 5 . The coating material for hot-dip molten zinc plated steel sheets according to claim 3, wherein the phosphoric acid compound (B) contains at least one selected from the group consisting of orthophosphoric acid, condensed phosphoric acid, and salts thereof. 6 . The coating material for hot-dip molten zinc plated steel sheet according to claim 4 , wherein the phosphoric acid compound (B) contains at least one selected from the group consisting of orthophosphoric acid, condensed phosphoric acid, and salts thereof. 7 . 7 . The coating material for hot-dip molten zinc plated steel sheet according to claim 1 , wherein the amine value (AV) of the cationic urethane resin (A) is 2.0 to 5.0 mgKOH/g. 8 . 8 . The coating material for hot-dip molten zinc plated steel sheet according to claim 2 , wherein the amine value (AV) of the cationic urethane resin (A) is 2.0 to 5.0 mgKOH/g. 9 . 9 . The coating material for hot-dip molten zinc plated steel sheet according to claim 3 , wherein the amine value (AV) of the cationic polyurethane resin (A) is 2.0 to 5.0 mgKOH/g. 10 . 10 . The coating material for hot dip galvanized steel sheet according to claim 4 , wherein the amine value (AV) of the cationic polyurethane resin (A) is 2.0 to 5.0 mgKOH/g. 11 . The amine value (AV) of the said cationic urethane resin (A) is 2.0-5.0 mgKOH/g, The coating material for hot-dip molten zinc-coated steel sheets of Claim 5. 12 . The coating material for hot dip galvanized steel sheet according to claim 6 , wherein the amine value (AV) of the cationic urethane resin (A) is 2.0 to 5.0 mgKOH/g. 13 . 13. The coating material for hot-dip molten zinc-coated steel sheet according to claim 9, wherein the content ratio (mass %) (BV) of the phosphoric acid compound (B) to the solid content of the cationic urethane resin and the amine The value ratio ((BV)/(AV)) is 0.1 to 9.5. 14. The coating material for hot-dip molten zinc plated steel sheet according to claim 10, wherein the content ratio (mass %) (BV) of the phosphoric acid compound (B) to the solid content of the cationic urethane resin and the amine The value ratio ((BV)/(AV)) is 0.1 to 9.5. 15. The coating material for hot-dip molten zinc plated steel sheet according to claim 11, wherein the content ratio (mass %) (BV) of the phosphoric acid compound (B) to the solid content of the cationic urethane resin and the amine The value ratio ((BV)/(AV)) is 0.1 to 9.5. 16. The coating material for hot-dip molten zinc plated steel sheet according to claim 12, wherein the content ratio (mass %) (BV) of the phosphoric acid compound (B) to the solid content of the cationic urethane resin and the amine The value ratio ((BV)/(AV)) is 0.1 to 9.5. 17. The coating material for hot-dip molten zinc plated steel sheet according to any one of claims 1 to 16, which further contains a trivalent chromium compound (C). 18. A method of processing a hot-dip galvanized steel sheet, which uses the coating material for a hot-dip galvanized steel sheet according to any one of claims 1 to 17 to process a hot-dip galvanized steel sheet. deal with. 19. A method for producing a surface-treated hot-dip hot-dip galvanized steel sheet, comprising the coating for a hot-dip galvanized steel sheet described in any one of claims 1 to 17 and a hot-dip hot-dip galvanized steel sheet A surface-treated hot-dip hot-dip hot-dip hot-dip hot-dip zinc-coated steel sheet having the above-mentioned hot-dip hot-dip hot-dip hot-dip hot-dip hot-dip zinc-coated steel sheet and a film disposed on the surface was produced. The surface-treated molten zinc-coated steel sheet obtained by the manufacturing method of Claim 19.