TWI683869B - Coating material for zinc hot-dip galvanized steel sheet, method for treating zinc hot-dip galvanized steel sheet, method for producing surface-treated zinc hot-dip galvanized steel sheet and surface-treated zinc-galvanized steel sheet - Google Patents

Abstract

The present invention provides a coating material for hot-dip galvanized hot-dip galvanized steel sheet that imparts excellent appearance characteristics, excellent friction resistance, and excellent corrosion resistance to hot-dip galvanized hot-dip galvanized steel sheet. The coating material for hot-dip galvanized hot-dip galvanized steel sheet of the present invention contains a cationic polyurethane resin having at least one cationic functional group selected from the group consisting of primary to tertiary amine groups and quaternary ammonium salt groups (A), the cationic polyurethane resin (A) has a polycarbonate structural unit and a bisphenol structural unit, and the temperature (Tg1) showing the maximum peak value of the loss elastic modulus E" of the cationic polyurethane resin (A) is -60 In the range of ℃~-5℃, the ratio of the loss elastic modulus E" of the cationic polyurethane resin (A) to the storage elastic modulus E', that is, the loss tangent tan δ is composed of a peak.

Description

Coatings for hot-dip galvanized hot-dip galvanized steel sheet, hot-dip galvanized hot-dip galvanized steel sheet processing method, surface treatment hot-dip galvanized hot-dip galvanized steel sheet manufacturing method, and surface-treated hot-dip galvanized steel sheet

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

Since the past, zinc-based plated steel plates including molten zinc plated steel plates, molten zinc-5% aluminum alloy plated steel plates, and molten zinc alloy plated steel plates have been widely used in home appliances and building materials. In addition, as a method of producing a zinc-based plated steel sheet, for example, "the dipping method in which the steel sheet as the object to be treated is immersed in a molten zinc bath to perform plating (so-called "hot-dip galvanized plating"), The method of applying molten zinc plating on the entire surface is also called hot-dip zinc-plated steel sheet. Furthermore, in the dipping method by hot dip plating (hereinafter, also referred to as In the hot dip plating method), the control of the amount of zinc adhesion by means of an air knife or the like carried out in CGL (Continuous Galvanizing Line) is not implemented.

Among zinc-based plated steel sheets, for the purpose of improving corrosion resistance, steel sheets subjected to perchromate treatment using a treatment liquid containing chromic acid, dichromic acid or its salts as main components are widely used.

However, chromate-treated coatings usually contain hexavalent chromium, which has a high environmental load. Therefore, in recent years, there has been an increasing demand for hexavalent chromium-free treatment of coatings, and various technologies have been proposed.

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

[Patent Document 1] Japanese Unexamined Patent Publication No. 2002-146554

On the other hand, in recent years, zinc-based plated steel sheets have been expanded to various uses, not only to further improve corrosion resistance, but also to improve other characteristics. Examples include: improvement of the appearance characteristics of zinc-based plated steel plates; or coatings (films arranged on zinc-based plated steel plates) marked as "marked with a cloth soaked with alcohol etc. during assembly work, etc. The ease of peeling of the "magic ink" operation is the improvement of the film's resistance (hereinafter referred to as friction resistance). Especially with regard to hot dip galvanized hot-dip galvanized steel sheets, there is a strong demand for improvement of the above characteristics (corrosion resistance, appearance characteristics, friction resistance).

The present inventors evaluated the above-mentioned various characteristics of the steel sheet obtained by applying the method described in Patent Document 1 to the hot-dip galvanized hot-dip galvanized steel sheet, and found that it was impossible It meets the appearance characteristics, friction resistance and corrosion resistance at the same time, which requires further improvement.

In view of the above-mentioned actual situation, the present invention aims to provide a hot dip galvanized hot-dip galvanized steel sheet (or molten zinc-plated steel sheet or zinc-plated steel sheet) that provides excellent appearance characteristics and excellent friction resistance And excellent corrosion resistance of hot-dip galvanized hot-dip galvanized steel sheet (or molten zinc-plated steel sheet or zinc-plated steel sheet) coating.

The present inventors have made intensive studies on the above-mentioned problems, and as a result, have found that by using a coating containing a cationic polyurethane resin exhibiting specific characteristics, the desired effect can be obtained.

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

(1) A coating material for hot dip galvanized hot-dip galvanized steel sheet, which contains a cationic polyurethane resin having at least one cationic functional group selected from the group consisting of primary to tertiary amine groups and quaternary ammonium salt groups (A), the cationic polyurethane resin (A) has a polycarbonate structural unit and a bisphenol structural unit, and the temperature (Tg1) showing the maximum peak value of the loss elastic modulus E" of the cationic polyurethane resin (A) is -60 In the range of ℃~-5℃, the ratio of the loss elastic modulus E" of the cationic polyurethane resin (A) to the storage elastic modulus E', that is, the loss tangent tan δ is composed of a peak.

(2) The coating material for hot dip galvanized steel sheet as described in (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 sheet as described in (1) or (2), which further contains a phosphoric acid compound (B).

(4) The coating material for hot-dip galvanized hot-dip galvanized steel sheet as described in (3), in which phosphoric acid is combined The substance (B) contains at least one selected from the group consisting of orthophosphoric acid, condensed phosphoric acid and salts of these.

(5) The coating material for hot-dip galvanized hot-dip galvanized steel sheet as described in 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 coating material for hot dip galvanized steel sheet as described in (5), wherein the content ratio (mass %) of the phosphoric acid compound (B) to the solid content of the cationic polyurethane resin (A) (BV) The ratio with amine value ((BV)/(AV)) is 0.1~9.5.

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

(8) A treatment method for hot-dip galvanized hot-dip galvanized steel sheet, using the hot-dip galvanized hot-dip galvanized steel sheet coating described in any one of (1) to (7) to perform hot-dip hot-dip galvanized steel plating Treatment of steel plates.

(9) A method for manufacturing a surface-treated hot-dip galvanized hot-dip galvanized steel sheet, which uses the hot-dip galvanized hot-dip galvanized steel sheet coating described in any one of (1) to (7) and hot-dip galvanized hot-dip galvanized steel plating The plated steel sheets are contacted to manufacture a surface-treated hot-dip zinc-plated steel sheet having a hot-dip molten zinc-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).

According to the present invention, it is possible to provide a hot-dip galvanized hot-dip galvanized steel sheet (or molten zinc-plated steel sheet or zinc-plated steel sheet) that provides excellent appearance characteristics, excellent friction resistance, and excellent corrosion resistance Paint for hot-dip galvanized hot-dip galvanized steel sheet (or molten zinc-plated steel sheet or zinc-plated steel sheet).

Furthermore, a hot-dip hot-dip galvanized steel sheet (or molten system) that "uses the coating to perform hot-dip hot-dip galvanized steel sheet (or molten zinc-plated steel sheet or zinc-plated steel sheet)" can be provided Zinc-plated steel plate or zinc-based plated steel plate); and "make the coating in contact with hot-dip molten zinc-plated steel plate (or molten zinc-plated steel plate or zinc-based plated steel plate) to produce hot-dip Hot-dip galvanized hot-dip galvanized steel sheet (or galvanized zinc-plated steel sheet or zinc) of surface treatment of hot-dip galvanized steel sheet (or molten zinc-plated steel sheet or zinc-plated steel sheet) and the film disposed on the surface Is a plated steel plate)" method and the steel plate.

In addition, the coating material for hot dip galvanized steel plate of the present invention is a technology without hexavalent chromium, but the performance is greatly improved by containing trivalent chromium. Moreover, even if it is in a form that does not contain trivalent chromium, it also exerts the desired effect.

Hereinafter, the coating material for hot dip galvanized hot-dip galvanized steel sheet 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 paint of the present invention is presumed as follows.

First, as the reason for the improvement in appearance characteristics, the aspect "the temperature at which the maximum peak (Tg1) showing the loss elastic modulus E of the cationic polyurethane resin is in the range of -60°C to -5°C" can be cited. The inventors found that the above temperature (Tg1) is related to the appearance characteristics of the film and the friction resistance. That is, the loss elastic modulus E" is an index representing the viscosity of an object. When the temperature of the maximum peak of "E" is too low, the resin exhibits good fluidity and the flatness of the coating is improved, so that excellent appearance characteristics can be obtained, but the hardness of the formed coating is poor, causing friction resistance. On the other hand, in the case where the above temperature is too high, although the formed film is excellent in hardness and excellent in friction resistance, the fluidity of the resin is reduced and the appearance characteristics are poor. In the present invention, it is found that cationic polyurethane When the temperature of the resin (Tg1) is within the above range, the appearance characteristics and the friction resistance can be taken into consideration. Furthermore, the above friction resistance means that the coating film is used as a symbol when it is wiped by a cloth impregnated with alcohol or the like during assembly work. "Operation marked with oil-based universal ink".

In addition, as a cause of improvement in corrosion resistance, the aspect "the loss tangent tan δ of the cationic polyurethane resin is composed of one peak" can be cited. Generally, the polyurethane resin easily forms a sea island structure having two or more regions of a soft segment and a hard segment in the film form due to its resin skeleton. Therefore, if dynamic viscoelasticity measurement is performed, two or more peaks are observed in the loss tangent tan δ. On the other hand, it is presumed that in the cationic polyurethane resin used in the present invention, the loss tangent tan δ is composed of one peak, and it is not easy to form the sea island structure in the film and form a uniform film. As a result, the corrosion resistance is improved.

In addition, in order to ensure good coating adhesion and impact resistance of the surface coating, the peak temperature (Tg2) of the loss tangent tan δ of the cationic polyurethane resin is preferably in the range of -50°C to -2°C. Depending on the environment in which the coating product of the present invention is used, processing may be carried out in cold areas. If it is a coating containing a component with a high peak temperature of loss tangent tan δ used in surface treatment, the film is hard, so especially when processing is carried out at low temperatures in winter, the coating of the surface coating is insufficient in adhesion and easy The coating film peeled off. In addition, if it is a paint containing a component with a lower peak temperature of the loss tangent tan δ used in surface treatment, the film is relatively soft, Therefore, especially when processing is carried out at a high temperature in summer, the impact resistance is insufficient, and the coating film is likely to peel off. In this regard, it is speculated that if the peak temperature (Tg2) of the loss tangent tan δ is in the range of -50°C to -2°C, the coating will have sufficient flexibility and hardness at low temperatures and at high temperatures, giving full play to the surface coating Layer coating adhesion and impact resistance.

In addition, in order to ensure good 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 helps to make the cationic polyurethane resin water-soluble or water-dispersible. Therefore, if there are fewer cationic functional groups, in other words, if the amine value is low, the stability of the cationic polyurethane resin is insufficient, and may be redispersed in the coating, but the resin is likely to precipitate. Therefore, in order to improve the stability of the cationic polyurethane resin, it is desirable to have more cationic functional groups, in other words, to make the amine value higher, but if the hydrophilic group in the resin is excessively increased, that is, the amine value is too high, there is a converse The cationic urethane resin melts in water, so the viscosity increases and the paint thickens, which affects the redispersibility of the paint. In addition, there are also cases where coating workability is affected due to viscosity increase. Therefore, it is presumed that by controlling the amine value of the cationic polyurethane resin to the range of 2.0 to 5.0 mgKOH/g, good storage stability can be obtained.

Furthermore, as other effects of the coating material of the present invention, it is also possible to mention that the phosphate treatment is excellent. The reason for the excellent phosphate handling property includes the aspect of "using a cationic polyurethane resin having a specific functional group". It is speculated that the cationic functional group in the cationic polyurethane resin formed in the coating on the hot dip galvanized hot-dip galvanized steel sheet interacts with the phosphoric acid present in the phosphoric acid compound to form phosphate such as zinc phosphate in the phosphate treatment The starting point of the reaction improves the phosphate treatment. The content ratio (mass %) (BV) of the phosphoric acid compound to the solid content of the cationic polyurethane resin (BV) and the ratio of the amine value (BV)/(AV) are not particularly limited The system may include 0.05 to 20, etc. Among them, preferably 0.1 to 9.5, more preferably 0.5 to 9.0, and still more preferably 0.5 to 6.0. It is presumed that if (BV)/(AV) is within the above range (0.1 to 9.5), the starting point of the formation reaction of phosphate is generated more favorably on the film, and more excellent phosphate handling property can be obtained. It is presumed that in this case, when there are relatively many phosphoric acid compounds, that is, (BV)/(AV) is relatively large, relatively many phosphoric acid compounds are eluted in the phosphate treatment solution, so in most cases, the formation of the phosphate film is likely to be delayed And, conversely, when there are relatively few phosphoric acid compounds, that is, (BV)/(AV) is relatively small, the interaction of the phosphoric acid compound with the cationic functional group of the cationic polyurethane resin is relatively less, so it is caused by the phosphate treatment solution. The resulting swelling or dissolution of the cationic polyurethane resin becomes low, and the formation of the phosphate film is likely to be delayed.

Furthermore, the phosphate treatment means the treatment using "a phosphate treatment solution with zinc phosphate, manganese phosphate, magnesium phosphate, etc. as the main component applied to the coating base layer." The coated phosphate treatment becomes one form of phosphate treatment. Coated phosphate treatment means "the formation of fine and dense zinc phosphate on the surface of the object to be processed (such as hot dip galvanized hot-dip galvanized steel plate and other zinc-plated steel plates) by the application of coated phosphate treatment liquid Crystallization, improving the sliding resistance on the friction joint surface with strong bolts", etc.

Furthermore, the coating material of the present invention can be suitably applied to hot-dip galvanized hot-dip galvanized steel sheets, and can also be suitably applied to hot-dip galvanized steel sheets manufactured by CGL (continuous molten zinc-plated board production line), etc. Zinc-plating of zinc-5% aluminum alloy plated steel sheet, molten zinc-55% molten aluminum alloy plated steel sheet, alloyed molten zinc plated steel sheet, electrogalvanized steel sheet manufactured by EGL (electrogalvanizing production line), etc. Clad steel plate can improve the above-mentioned various characteristics (appearance characteristics, friction resistance, corrosion resistance, surface coating coating adhesion, impact resistance, phosphate treatment, etc.). In other words, the coating of the present invention can be suitably applied to zinc-based plated steel sheets, and can also be used as zinc-based plating Coatings for steel plates. Especially suitable for hot dip galvanized hot-dip galvanized steel plate, hot-dip galvanized steel plate produced by CGL (continuous hot-dip galvanized plate production line), etc., molten zinc-5% aluminum alloy plated steel plate, molten zinc- 55% molten aluminum alloy plated steel plates, alloyed molten zinc plated steel plates, and the like, which are molten zinc plated steel plates obtained by performing plating treatment with molten zinc, can also be used as coatings for molten zinc plated steel plates.

The coating of the present invention contains at least a cationic polyurethane resin (A).

Hereinafter, the various components contained in the paint will be described in detail, and then, the treatment method of the hot-dip galvanized steel sheet using the paint (in other words, manufacturing the hot-dip galvanized steel sheet and disposing it thereon) The surface treatment of the coating on the surface of the hot-dip galvanized hot-dip galvanized steel sheet is described 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 the group consisting of primary to tertiary amine groups and quaternary ammonium salt groups.

The anionic resins used in the conventional technology generally have poor alkali resistance and excellent acid resistance. In the case where the alkali resistance is poor, the film is easily dissolved and peeled due to the alkaline degreasing step after the film formation, etc., which causes a decrease in corrosion resistance. In addition, since it is excellent in acid resistance, it is difficult to perform phosphate treatment in many cases. On the other hand, the cationic polyurethane resin (A) has excellent alkali resistance, and therefore has excellent corrosion resistance after the alkaline degreasing step. In addition, the polyurethane resin is toughened due to the hydrogen bond derived from the amine ester bond in the molecule, thereby improving the corrosion resistance. Furthermore, relatively, there are also cases where there are cationic functional groups, and the acid resistance is low, so the characteristics as a resin are also easy to perform phosphate treatment.

(Cationic functional group)

Examples of the cationic functional group contained in the cationic polyurethane resin (A) include amine groups, methylamino groups, ethylamino groups, dimethylamino groups, diethylamino groups, and trimethylamine. The group, the triethylamine group and the like are not particularly limited as long as they are a primary to tertiary amine group or a quaternary ammonium salt group.

Furthermore, the cationic functional group in the cationic polyurethane resin (A) helps to make the cationic polyurethane resin (A) water-soluble or water-dispersible. Furthermore, the dissolution or dispersion of the cationic polyurethane resin (A) in water can be achieved based on the self-solubility or self-dispersibility of the cationic polyurethane resin (A) in water, or by means of a cationic surfactant (e.g. Alkyl quaternary ammonium salt) and/or nonionic surfactant (for example, alkyl phenyl ether).

(The temperature showing the maximum peak of the loss elastic modulus E" (Tg1))

The temperature (Tg1) showing the maximum peak value of the loss elastic modulus E" of the cationic polyurethane resin (A) is in the range of -60 ℃ ~ -5 ℃, in terms of appearance characteristics, friction resistance, corrosion resistance, phosphate treatment , At least one of the surface coating coating adhesion, impact resistance, and storage stability is more excellent (hereinafter, also referred to as "the aspect of the present invention is more excellent"), preferably -55 ℃~-10℃, more preferably -50℃~-15℃.

When the temperature (Tg1) does not reach -60°C, the friction resistance is poor, and when it exceeds -5°C, the appearance characteristics of the coating are poor.

In addition, the above-mentioned maximum peak value means the loss elastic modulus curve obtained by the following dynamic viscoelasticity measurement (the horizontal axis is temperature, and the vertical axis is loss elastic modulus). The largest of the peaks observed in the temperature dependence curve of the number. The peak value can also be called the so-called maximum value.

(Loss tangent tan δ)

Ratio of loss elastic modulus E" of cationic polyurethane resin (A) to storage elastic modulus E'(loss The loss elastic modulus E"/storage elastic modulus E') is the loss tangent tan δ is composed of a peak (only one peak). That is, it means the loss tangent tan obtained by the following dynamic viscoelasticity measurement The delta curve (the temperature dependence of the horizontal axis is the temperature and the vertical axis is the temperature dependence of the loss tangent tan δ in the graph of the loss tangent tan δ) consists of one peak (only one peak). In other words, it means There is no more than two peaks. As mentioned above, when more than two 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, and in terms of more excellent effects of the present invention (especially the adhesion and impact resistance of the surface coating), it is preferably -50°C ~-2°C, more preferably -48°C~-5°C, still more preferably -45°C~-10°C.

As a method of dynamic viscoelasticity measurement, using the dynamic viscoelasticity measuring device "RSAG2" manufactured by TA Instruments, the transverse direction of the film (sample area: clamping length x width = 20 mm x 5 mm) of the cationic polyurethane resin (A) ( TD), under the condition of vibration frequency of 10 Hz and strain of 0.1%, measured at a heating rate of 5 °C/min from -100 °C to 200 °C to calculate the storage elastic modulus E', loss elastic modulus E" and loss tangent tan δ.

The above characteristics (loss elastic modulus E", loss tangent tan δ) of the cationic polyurethane resin (A) contained in the coating material of the present invention can be appropriately adjusted by controlling its 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 polyurethane resin (A), or the temperature at the time of polymerization. When the amount of polyol is large, the temperature (Tg1) becomes low, and when the amount is small, the temperature (Tg1) tends to be high.

In addition, in order not to observe more than two peaks of loss tangent tan δ, for example, there is a control It is a method of the molecular weight of the polyol constituting the soft segment of the cationic polyurethane resin (A) or the temperature at the time of 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 polycarbonate structural repeating unit and a bisphenol structural repeating unit as repeating units constituting the resin.

Although the carbonate structural unit has flexibility and excellent adhesion, it tends to have poor hydrolysis resistance when the film is wetted in water or the like. Although the bisphenol structural unit is excellent in hydrolysis resistance, it has a tendency to be hard and poor in flexibility, and is liable to be damaged due to friction or the like.

That is, if the polycarbonate structural unit and the bisphenol structural unit are not included, the corrosion resistance and the friction resistance are inferior to those having the polycarbonate structural unit and the bisphenol structural unit.

In the present invention, the combination of the two is controlled so that the temperature (Tg1) showing the maximum peak value of the loss elastic modulus E" becomes the range of -60°C to -5°C, whereby excellent corrosion resistance and friction resistance can be obtained at the same time And excellent appearance characteristics.

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

Examples of polycarbonate polyols include ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, and 3 -Methyl-1,5-pentanediol, 1,9-nonanediol, 1,8-nonanediol, neopentyl glycol, diethylene glycol, dipropylene glycol, 1,4-cyclohexanediol, 1,4 -Polycarbonate polyols with hydroxyl groups at the ends obtained by reacting polyols such as cyclohexanedimethanol, bisphenol A, or hydrogenated bisphenol A with dimethyl carbonate, diphenyl carbonate, ethyl carbonate, or phosgene Alcohol etc.

Examples of the bisphenol structural unit include structural units derived from bisphenol A, bisphenol F, or bisphenol S. As a method of introducing a bisphenol structural unit into the cationic polyurethane resin (A), a method of producing a cationic polyurethane resin (A) using a polyol having a bisphenol structure can be mentioned.

Examples of polyhydric alcohols having a bisphenol structure include polyhydric alcohols obtained by adding alkylene oxide to bisphenol A type, bisphenol F type, bisphenol E type, and bisphenol A type; Polyol obtained by adding alkylene oxide to phenol F type; polyol obtained by adding alkylene oxide to bisphenol E type; addition to hydrogenated bisphenol A type, hydrogenated bisphenol F type, and hydrogenated bisphenol A type Polyols made from alkylene oxide; polyols made from hydrogenated bisphenol F type alkylene oxide; etc.; polyols made from hydrogenated bisphenol E type alkylene oxide.

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

For example, when manufacturing the cationic polyurethane resin (A), other polyols than polycarbonate polyols such as polyether polyols and polyester polyols may be used together.

In addition, when manufacturing the cationic polyurethane resin (A), an alcohol compound having a cationic functional group such as (substituted) amine group (preferably a multicomponent having a cationic functional group such as (substituted) amine group) may be used together Alcohol compounds) (such as N-methyldiethanolamine, N,N-dimethylaminodimethylolpropane, etc.), or amine compounds with specific cationic functional groups, and the desired cationic functional groups Introduced into polyurethane resin.

In addition, as described above, when producing the cationic polyurethane resin (A), the above polyol and Polyisocyanate (for example, aliphatic, alicyclic or aromatic polyisocyanate) is obtained by reaction.

Examples of polyether polyols include polyethylene glycols such as diethylene glycol and triethylene glycol, and polyethylene/propylene glycol.

Examples of polyester polyols include alkylene (e.g. carbon number 1 to 6) glycols (ethylene glycol, propylene glycol, butylene glycol, neopentyl glycol, hexamethylene glycol, etc.), Polyols such as ether polyols, bisphenol A, hydrogenated bisphenol A, trimethylolpropane or glycerol and succinic acid, glutaric acid, adipic acid, sebacic acid, phthalic acid, isophthalic acid, Polyester polyols with hydroxyl groups at the ends obtained by polycondensation of polyacids such as terephthalic acid or 1,2,4-benzenetricarboxylic acid.

As the aliphatic, alicyclic or aromatic polyisocyanate, tolylene diisocyanate (tolylene diisocyanate), diphenylmethane diisocyanate, xylylene diisocyanate (xylylene diisocyanate), dicyclohexylmethane diisocyanate, cyclic Hexane diisocyanate (cyclohexylene diisocyanate), hexamethylene diisocyanate, amine diisocyanate, etc.

(Amine value)

The amine value of the cationic polyurethane resin (A) is not particularly limited. As far as the storage stability of the coating is more excellent, it is preferably 2.0 to 5.0 mgKOH/g, more preferably 2.3 to 4.5 mgKOH/g, and further Preferably it is 2.5~4.0mgKOH/g.

In the above amine value, the value measured by the following measuring method is defined as the total amine value.

Approximately 3 g of cationic polyurethane resin (A) converted into solid content is taken and accurately weighed. Thereafter, dimethylformamide is added and dissolved. Then, add a few drops of bromocresol green indicator, titrate with 0.1 mol/L hydrochloric acid titration solution, and read the amount of titrant with the point that changes from blue to yellow 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]

In the formula:

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

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

f: Power value of 0.1mol/L hydrochloric acid titration solution

S: Amount of sample taken (g).

In addition, the above-mentioned blank test means a test using deionized water instead of a cationic polyurethane resin.

<any other ingredients>

The coating material of the present invention may contain other components than the above-mentioned cationic polyurethane resin (A). Hereinafter, the arbitrary components will be described in detail.

(Phosphoric acid compound (B))

The paint of the present invention may also contain a phosphoric acid compound (B). By containing the phosphoric acid compound (B), the corrosion resistance is further improved.

Examples of the phosphoric acid compound (B) include at least one selected from the group consisting of inorganic phosphoric acid, inorganic phosphate, organic phosphoric acid, and organic phosphate.

Examples of inorganic phosphoric acid and its salts include phosphoric acid (orthophosphoric acid), phosphorous acid, triphosphoric acid, hypophosphorous acid, hypophosphorous acid and other monophosphoric acid, derivatives of monophosphoric acid and salts, metaphosphoric acid, tripolyphosphoric acid, tetraphosphoric acid , Hexaphosphoric acid and other condensed phosphoric acid, derivatives and salts of condensed phosphoric acid, etc.

Examples of the organic phosphoric acid and its salts include: phosphoric acid monoesters (e.g., monododecyl dihydrogen phosphate, monotridecyl dihydrogen phosphate, etc.) and their salts, and phosphoric acid diesters (e.g., di-dodecyl hydrogen phosphate, phosphoric acid) Hydrogen tri-tridecyl ester, etc.) and its salts. Specific examples of the organic phosphoric acid include compounds represented by R ₁₀ OP(=O)(OR ₁₁ )(OR ₁₂ ). 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 the organic group, for example, a hydrocarbon group (for example, an alkyl group, an aryl group, or a group obtained by combining these) can be mentioned.

In addition, the salts such as inorganic phosphate (salt of inorganic phosphate) and organic phosphate (salt of organic phosphate) are not particularly limited, and examples thereof include alkali metal salts, ammonium salts, and amine salts.

Among them, in terms of more excellent effects of the present invention, 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 of these.

(Trivalent chromium compound (C))

The paint of the present invention may also contain a trivalent chromium compound (C). By containing the trivalent chromium compound (C), the corrosion resistance is further improved.

The trivalent chromium compound (C) is a compound that can supply trivalent chromium ions, and examples thereof include trivalent chromium salts. Examples of the types of salts include inorganic acid salts such as nitrate, sulfate, and hydrochloride; organic acid salts such as acetate, oxalate, and succinate.

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

(Solvent)

The paint of the present invention may also contain a solvent. Examples of the solvent include water and organic solvents (for example, alcohol).

(Other additives)

For the purpose of adjusting the applicability, the coating of the present invention may also contain a tackifier, leveling agent, wettability enhancer, defoaming agent, surfactant, water-soluble alcohols, Celusus-based solvents, and the like.

In addition, it may contain preservatives, antibacterial agents, colorants, anti-damage agents, lubricants, and the like.

In addition, it may contain benzotriazole, a guanidine-based compound, a hindered amine, and the like.

<Paint for hot dip galvanized molten zinc plating steel plate>

The above-mentioned various components are contained in the paint of the present invention.

The content of the cationic polyurethane resin (A) in the paint is not particularly limited, as far as the effect of the present invention is more excellent and the operability is 1 to 40% by mass relative to the total mass of the paint. It is more preferably 5 to 30% by mass.

When the phosphoric acid compound (B) is contained in the paint, the content of the phosphoric acid compound (B) is not particularly limited, as far as the effect of the present invention is more excellent, relative to 100 parts by mass of the cationic polyurethane resin (A), It is preferably 0.1 to 30 parts by mass, more preferably 0.3 to 25 parts by mass, and still more preferably 1 to 10 parts by mass.

When the trivalent chromium compound (C) is contained in the paint, the content of the trivalent chromium compound (C) is not particularly limited, as far as the effect of the present invention is more excellent, compared to the cationic polyurethane resin (A) 100 parts by mass, preferably 0.5 to 20 parts by mass, more preferably 1 to 10 parts by mass.

The method for preparing the paint is not particularly limited, and for example, it can be prepared by adding the cationic polyurethane resin (A) and other arbitrary components to a solvent such as water and mixing them.

<Manufacturing method of hot dip galvanized steel plate with surface treatment>

The coating of the present invention can be suitably applied to hot dip galvanized hot-dip galvanized steel sheet. By making the coating of the present invention contact with the hot-dip hot-dip galvanized steel sheet, the hot-dip galvanized hot-dip galvanized steel sheet can be manufactured and arranged in The surface treatment of the film on the surface is hot-dip galvanized hot-dip galvanized steel sheet.

In addition, as described above, the coating material of the present invention can also be suitably applied to zinc-plated steel sheets (or molten zinc-plated steel sheets) including hot-dip molten zinc-plated steel sheets.

Hereinafter, the state of using the hot-dip galvanized hot-dip galvanized steel sheet as a to-be-processed object will be described typically, but zinc plating other than the hot-dip galvanized hot-dip galvanized steel sheet may be performed under the following conditions A specific coating is formed on the steel plate to produce surface-treated zinc-based plated steel plates with various excellent characteristics. In addition, in the case of using the above-mentioned molten zinc-plated steel sheet, a surface-treated molten zinc-plated steel sheet having a molten zinc-plated steel sheet and a film disposed thereon can also be manufactured.

The method for manufacturing the surface-treated hot-dip galvanized hot-dip galvanized steel sheet using the above coating is not particularly limited, and generally has the following steps: the above-mentioned coating is brought into contact with the hot-dip galvanized hot-dip galvanized steel sheet, heat-dried if necessary, and then hot-dipped A film was formed on the molten zinc-plated steel sheet to obtain a surface-treated hot-dip molten zinc-plated steel sheet.

In the following, first, the hot-dip galvanized steel sheet to be processed will be described in detail, and then, the sequence of steps will be described in detail.

(Hot dip galvanized steel sheet)

The hot-dip galvanized hot-dip galvanized steel sheet is a steel sheet obtained by a dipping method in which a steel sheet to be treated is immersed in a molten zinc bath, and the treated body is slowly and directly pulled from the plating bath, thereby Perform plating. In addition, as described above, in the hot dip plating method, the amount of zinc adhesion controlled by an air knife or the like is not implemented in CGL, but the object to be treated is pulled from the plating tank and placed directly (cooling ).

There are no particular restrictions on the type of steel plate that is hot-dip galvanized. For example, it can be used for H-beams, guard rails, corrugated pipes, columns or beams in buildings, sound-proof wall pillars, sign posts, lighting columns, and large bridge truss bridges. , All kinds of construction materials for zinc plating, such as bridges, steel bridges, steel towers, power towers and other wire metal appliances, bolts and nuts, small solar cells or small wind power generators, outdoor exposed steel frames, etc. It can also be cut steel or coiled steel.

Furthermore, when oil content, dirt, etc. adhere to the surface of the hot dip galvanized hot-dip galvanized steel plate, it is preferably cleaned with an alkaline degreasing agent, neutral degreasing agent, acid degreasing agent, etc., Thereafter, hot water washing or water washing is performed to make the surface condition clean.

(Contact method of paint)

The coating method is not particularly limited to the method of contacting the hot dip galvanized hot-dip galvanized steel sheet, and examples include dipping treatment, spray treatment, brush painting treatment, and electrostatic painting treatment performed in the cooling step after the plating process. In addition, when the hot-dip galvanized hot-dip galvanized steel plate is coiled, conventional methods can be applied, for example, roll coating, shower wringer roll twisting, spray treatment, dipping treatment , Curtain coat, flow coat, spin coat, etc.

(Drying method of paint)

As the drying method of the paint, the most economical method is to use the preheating method after the plating process. The hot-dip galvanized molten zinc-plated steel plate can be dipped in the paint and placed directly for drying. In addition, during drying, the wind for efficiently blowing off the moisture attached to the surface of the hot-dip galvanized hot-dip galvanized steel sheet can also be blown.

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

(Coating amount of paint)

By performing the above treatment, a surface-treated hot-dip galvanized steel sheet having a hot-dip galvanized zinc-plated steel sheet and a film disposed on the surface thereof is manufactured.

The adhesion amount of the film is not particularly limited, and in terms of more excellent effects of the present invention, it is preferably 0.3 to 5.0 g/m ² , and more preferably 0.5 to 3.0 g/m ² .

The manufactured surface-treated hot-dip galvanized hot-dip galvanized steel sheet can be suitably used for various applications, for example, components for home appliances and building materials.

In addition, the surface-treated hot-dip galvanized hot-dip galvanized steel sheet may be coated. In this case, there are also cases where certain processing is further performed on the coated board.

[Example]

Hereinafter, examples and comparative examples of the present invention will be listed to specifically explain the present invention, but the present invention is not limited to these examples.

1. Test materials

The test materials (raw materials) used are described below. In general, hot-dip galvanized products are shaped in many cases, but in this test, the board is used as the raw material. Furthermore, even if the shape of the raw material is changed, it will not have any effect on the effect exhibited by the present invention.

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

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

M2: Molten zinc plated steel plate (according to JIS G 3302 SGCC Z06), size: 700mm×150mm×0.8mm (plate thickness), double-sided plating adhesion: 60g/m ²

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

2. Pre-treatment (degreasing treatment)

Fine Cleaner E6406 (manufactured by Nihon Parkerizing Co., Ltd.) using a silicate-based alkaline degreasing agent was sprayed on the above test materials for 10 seconds under the conditions of a concentration of 20 g/L and a temperature of 60°C. Furthermore, it was washed with pure water for 30 seconds, and then dried. The dried person was used in the following test.

3. Paint

Table 1 shows the details of the cationic polyurethane resin (A) used. In addition, the manufacturing method will be described in detail later.

The loss elastic modulus E" and loss tangent tan δ of the cationic polyurethane resin (A) are measured in the following order. First, the film (thickness: 300~500 μm) of the cationic polyurethane resin (A) is placed at room temperature After 15 hours, it was dried at 80°C for 6 hours, and further dried at 120°C for 20 minutes.

Next, using the dynamic viscoelasticity measuring device "RSAG2" manufactured by TA Instruments, the transverse direction (TD) of the obtained film (sample area: clamping length x width = 20 mm x 5 mm) was at a vibration frequency of 10 Hz and a strain of 0.1% Under conditions, the temperature is measured from -100°C to 200°C at a heating rate of 5°C/min, and the storage elastic modulus E', the loss elastic modulus E" and the loss tangent tan δ are calculated. Furthermore, the jig (chuck) The distance between them is set to 10mm.

The method of measuring the amine value is as described above.

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

Also, the peak number means the ratio of the loss elastic modulus E" to the storage elastic modulus E', that is, the loss tangent The number of peaks in the temperature dependence curve of tan δ.

(Production Example 1: Cationic polyurethane resin (A1))

In a four-necked flask equipped with a stirrer, a reflux cooling tube, a thermometer, and a nitrogen blowing tube, 1000 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 parts by mass was allowed to react at 75°C for 4 hours to obtain a methyl ethyl ketone solution of an amine ester prepolymer having a content of free isocyanate groups of 3.0% by mass relative to nonvolatile components. The solution was cooled to 40°C, and dimethyl sulfate 103 mass was added After 2 parts, 2700 parts by mass of deionized water was slowly added for emulsification and dispersion. Thereafter, 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 under reduced pressure at 50° C. to obtain a polyurethane aqueous dispersion 1 containing a cationic polyurethane resin (A1) having a nonvolatile content of about 35% by mass.

(Production Example 2: Cationic polyurethane resin (A2))

In a four-necked flask equipped with a stirrer, a reflux cooling tube, a thermometer, and a nitrogen blowing tube, add 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 parts by mass was allowed to react at 75°C for 4 hours to obtain a methyl ethyl ketone solution of an amine ester prepolymer having a content of free isocyanate groups of 3.0% by mass relative to nonvolatile components. The solution was cooled to 40°C, 47 mass parts of dimethyl sulfate was added, and then 2700 mass parts of deionized water was slowly added for emulsification and dispersion. Thereafter, 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° C. under reduced pressure to obtain polyurethane aqueous dispersion 2 containing a cationic polyurethane resin (A2) having a nonvolatile content of about 35% by mass.

(Production Example 3: Cationic polyurethane resin (A3))

In a four-necked flask equipped with a stirrer, a reflux cooling tube, a thermometer, and a nitrogen blowing tube, 1000 parts by mass of polycarbonate polyol (Nippollan 980, manufactured by Tosoh Corporation, Mw=1,000), bisphenol A-bis( Hydroxyethyl 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 di 250 parts by mass of isocyanate, methyl ethyl 800 parts by mass of ketone was reacted at 75°C for 4 hours to obtain a methyl ethyl ketone solution of an amine ester prepolymer with a content of free isocyanate groups of 3.0% by mass relative to nonvolatile components. The solution was cooled to 40°C, 95 mass parts of dimethyl sulfate was added, and then 2700 mass parts of deionized water was slowly added for emulsification and dispersion. Thereafter, 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° C. under reduced pressure to obtain polyurethane aqueous dispersion 3 containing a cationic polyurethane resin (A3) having a nonvolatile content of about 35% by mass.

(Production Example 4: Cationic polyurethane resin (A4))

In a four-necked flask equipped with a stirrer, a reflux cooling tube, a thermometer, and a nitrogen blowing tube, 1000 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 parts by mass was allowed to react at 75°C for 4 hours to obtain a methyl ethyl ketone solution of an amine ester prepolymer having a content of free isocyanate groups of 3.0% by mass relative to nonvolatile components. This solution was cooled to 40°C, and after adding 101 parts by mass of dimethyl sulfate, 2700 parts by mass of deionized water was slowly added for emulsification and dispersion. Thereafter, 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° C. under reduced pressure to obtain polyurethane aqueous dispersion 4 containing a cationic polyurethane resin (A4) having a nonvolatile content of about 35% by mass.

(Production Example 5: Cationic polyurethane resin (A5))

In a four-necked flask equipped with a stirrer, a reflux cooling tube, a thermometer, and a nitrogen blowing tube, add 1500 parts by mass of polycarbonate polyol (Nippollan 981R, manufactured by Tosoh Corporation, Mw=2,000), bisphenol A-bis( Hydroxyethyl ether) (BPE20T, Sanyo Chemical Co., Ltd. Manufactured, hydroxyl value 346 mg/g) 100 parts by mass, 50 parts by mass of N-methyldiethanolamine, 370 parts by mass of hexamethylene diisocyanate, and 800 parts by mass of methyl ethyl ketone, and reacted at 75°C for 4 hours. A methyl ethyl ketone solution of an amine ester prepolymer having a content of free isocyanate groups with respect to nonvolatile components of 3.0% by mass was obtained. The solution was cooled to 40°C, 48 parts by mass of dimethyl sulfate was added, and then 2700 parts by mass of deionized water was slowly added for emulsification and dispersion. Thereafter, 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° C. under reduced pressure to obtain polyurethane aqueous dispersion 5 containing a cationic polyurethane resin (A5) having a nonvolatile content of about 35% by mass.

(Production Example 6: Cationic polyurethane resin (A6))

In a four-necked flask equipped with a stirrer, a reflux cooling tube, a thermometer, and a nitrogen blowing tube, 1000 parts by mass of polycarbonate polyol (Nippollan 980, manufactured by Tosoh Corporation, Mw=1,000), 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, 450 parts by mass of hexamethylene diisocyanate, dicyclohexylmethane di 220 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 methyl ethyl group of an amine ester prepolymer having a content of free isocyanate groups of 3.0% by mass relative to nonvolatile components. Ketone solution. The solution was cooled to 40°C, 87 mass parts of dimethyl sulfate was added, and then 2700 mass parts of deionized water was slowly added for emulsification and dispersion. Thereafter, 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° C. under reduced pressure to obtain polyurethane aqueous dispersion 6 containing a cationic polyurethane resin (A6) having a nonvolatile content of about 35% by mass.

(Production Example 7: Cationic polyurethane resin (A7))

In a four-necked flask equipped with a stirrer, reflux cooling tube, thermometer and nitrogen blowing tube, add Polycarbonate polyol (Nippollan 981R, manufactured by Tosoh Corporation, Mw=2,000) 1500 parts by mass, bisphenol A-bis(hydroxyethyl ether) (BPE20T, manufactured by Sanyo Chemical Co., Ltd., hydroxyl value 346mg/ g) 100 parts by mass, 50 parts by mass of N-methyldiethanolamine, 260 parts by mass of hexamethylene diisocyanate, 150 parts by mass of dicyclohexylmethane diisocyanate, and 800 parts by mass of methyl ethyl ketone, at 75°C After reaction for 4 hours, a methyl ethyl ketone solution of an amine ester prepolymer having a content of free isocyanate groups with respect to nonvolatile components of 3.0% by mass was obtained. The solution was cooled to 40°C, 49 mass parts of dimethyl sulfate was added, and then 2700 mass parts of deionized water was slowly added for emulsification and dispersion. Thereafter, 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 under reduced pressure at 50° C. to obtain a polyurethane aqueous dispersion 7 containing a cationic polyurethane resin (A7) having a nonvolatile content of about 35% by mass.

(Production Example 8: Cationic polyurethane resin (A8))

In a four-necked flask equipped with a stirrer, a reflux cooling tube, a thermometer, and a nitrogen blowing tube, add 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, dicyclohexylmethane di 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 methyl ethyl group of an amine ester prepolymer having a free isocyanate group content of 3.0% by mass relative to non-volatile components. Ketone solution. The solution was cooled to 40°C, 49 mass parts of dimethyl sulfate was added, and then 2700 mass parts of deionized water was slowly added for emulsification and dispersion. Thereafter, 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° C. under reduced pressure to obtain polyurethane aqueous dispersion 8 containing a cationic polyurethane resin (A8) having a nonvolatile content of about 35% by mass.

(Production Example 9: Cationic polyurethane resin (A9))

In a four-necked flask equipped with a stirrer, a reflux cooling tube, a thermometer, and a nitrogen blowing tube, add 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, dicyclohexylmethane di 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 methyl ethyl group of an amine ester prepolymer with a content of free isocyanate groups of 3.0% by mass relative to nonvolatile components. Ketone solution. The solution was cooled to 40°C, 49 mass parts of dimethyl sulfate was added, and then 2700 mass parts of deionized water was slowly added for emulsification and dispersion. Thereafter, 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° C. under reduced pressure to obtain polyurethane aqueous dispersion 9 containing a cationic polyurethane resin (A9) having a nonvolatile content of about 35% by mass.

(Production Example 10: Cationic polyurethane resin (A10))

In a four-necked flask equipped with a stirrer, a reflux cooling tube, a thermometer and a nitrogen blowing tube, add 750 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) 125 parts by mass, N-methyldiethanolamine 50 parts by mass, hexamethylene diisocyanate 290 parts by mass, dicyclohexylmethane di 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 methyl ethyl group of an amine ester prepolymer with a content of free isocyanate groups of 3.0% by mass relative to nonvolatile components. Ketone solution. The solution was cooled to 40°C, and after adding 51 parts by mass of dimethyl sulfate, 2700 parts by mass of deionized water was slowly added to emulsify and disperse. Thereafter, 45 parts by mass of ethylenediamine was dissolved in 100 g of water. The aqueous solution was continuously stirred for 1 hour. This was desolvated at 50° C. under reduced pressure to obtain a polyurethane water dispersion 10 containing a cationic polyurethane resin (A10) having a nonvolatile content of about 35% by mass.

(Production Example 11: Cationic polyurethane resin (A11))

In a four-necked flask equipped with a stirrer, a reflux cooling tube, a thermometer and a nitrogen blowing tube, add 750 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) 125 parts by mass, N-methyldiethanolamine 50 parts by mass, hexamethylene diisocyanate 220 parts by mass, dicyclohexylmethane di 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 methyl ethyl group of an amine ester prepolymer with a content of free isocyanate groups of 3.0% by mass relative to nonvolatile components. Ketone solution. The solution was cooled to 40°C, and after adding 50 parts by mass of dimethyl sulfate, 2700 parts by mass of deionized water was slowly added for emulsification and dispersion. Thereafter, 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° C. under reduced pressure to obtain polyurethane aqueous dispersion 11 containing a cationic polyurethane resin (A11) having a nonvolatile content of about 35% by mass.

(Production Example 12: Cationic polyurethane resin (A12))

In a four-necked flask equipped with a stirrer, a reflux cooling tube, a thermometer and a nitrogen blowing tube, 500 parts by mass of polycarbonate polyol (Nippollan 980, manufactured by Tosoh Corporation, Mw=1,000), polycarbonate polyol ( Nippollan 981R, manufactured by Tosoh Corporation, Mw=2,000) 250 parts by mass, bisphenol A-bis(hydroxyethyl ether) (BPE20T, manufactured by Sanyo Chemicals Co., Ltd., hydroxyl value 346mg/g) 150 parts by mass, N -Methyldiethanolamine 50 quality Parts by weight, 275 parts by mass of hexamethylene diisocyanate, 150 parts by mass of dicyclohexylmethane diisocyanate, and 800 parts by mass of methyl ethyl ketone, which were reacted at 75°C for 4 hours to obtain free isocyanate groups that are relatively nonvolatile The content of the component is 3.0% by mass of a methyl ethyl ketone solution of an amine ester prepolymer. The solution was cooled to 40°C, 44 parts by mass of dimethyl sulfate was added, and then 2700 parts by mass of deionized water was slowly added for emulsification and dispersion. Thereafter, 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° C. under reduced pressure to obtain a polyurethane aqueous dispersion 12 containing a cationic polyurethane resin (A12) having a nonvolatile content of about 35% by mass.

(Production Example 13: Cationic polyurethane resin (A13))

In a four-necked flask equipped with a stirrer, a reflux cooling tube, a thermometer, and a nitrogen blowing tube, add 1500 parts by mass of polycarbonate polyol (Nippollan 980, manufactured by Tosoh Corporation, Mw=1,000), and bisphenol A-bis( Hydroxyethyl 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, methyl ethyl ketone 800 parts by mass was allowed to react at 75°C for 4 hours to obtain a methyl ethyl ketone solution of an amine ester prepolymer having a content of free isocyanate groups of 3.0% by mass relative to nonvolatile components. The solution was cooled to 40°C, 49 mass parts of dimethyl sulfate was added, and then 2700 mass parts of deionized water was slowly added for emulsification and dispersion. Thereafter, 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 under reduced pressure at 50° C. to obtain a polyurethane aqueous dispersion 13 containing a cationic polyurethane resin (A13) having a nonvolatile content of about 35% by mass.

(Production Example 14: Cationic polyurethane resin (A14))

In a four-necked flask equipped with a stirrer, reflux cooling tube, thermometer and nitrogen blowing tube, add Polycarbonate polyol (Nippollan 980, manufactured by Tosoh Corporation, Mw=1,000) 1500 parts by mass, bisphenol A-bis(hydroxyethyl ether) (BPE20T, manufactured by Sanyo Chemical Co., Ltd., hydroxyl value 346mg/ g) 25 parts by mass, 50 parts by mass of N-methyldiethanolamine, 500 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 free isocyanate groups. In a methyl ethyl ketone solution of an amine ester prepolymer with a nonvolatile content of 3.0% by mass. The solution was cooled to 40°C, and after adding 25 parts by mass of dimethyl sulfate, 2700 parts by mass of deionized water was slowly added for emulsification and dispersion. Thereafter, 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° C. under reduced pressure to obtain a polyurethane water dispersion 14 containing a cationic polyurethane resin (A14) having a nonvolatile content of about 35% by mass.

(Production Example 15: Cationic polyurethane resin (A15))

In a four-necked flask equipped with a stirrer, a reflux cooling tube, a thermometer, and a nitrogen blowing tube, add 1600 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 346mg/g) 150 parts by mass, N-methyldiethanolamine 50 parts by mass, hexamethylene diisocyanate 245 parts by mass, dicyclohexylmethane di 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 methyl ethyl of an amine ester prepolymer having a content of free isocyanate groups of 3.0% by mass relative to nonvolatile components Ketone solution. The solution was cooled to 40°C, 48 parts by mass of dimethyl sulfate was added, and then 2700 parts by mass of deionized water was slowly added for emulsification and dispersion. Thereafter, 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° C. under reduced pressure to obtain a polyurethane aqueous dispersion containing a cationic polyurethane resin (A15) having a nonvolatile content of about 35% by mass. 15.

(Production Example 16: Cationic polyurethane resin (A16))

In a four-necked flask equipped with a stirrer, a reflux cooling tube, a thermometer, and a nitrogen blowing tube, 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) 50 parts by mass, 175 parts by mass of N-methyldiethanolamine, 550 parts by mass of hexamethylene diisocyanate, methyl ethyl ketone 800 parts by mass was allowed to react at 75°C for 4 hours to obtain a methyl ethyl ketone solution of an amine ester prepolymer having a content of free isocyanate groups of 3.0% by mass relative to nonvolatile components. The solution was cooled to 40°C, and after adding 179 parts by mass of dimethyl sulfate, 2700 parts by mass of deionized water was slowly added for emulsification and dispersion. Thereafter, 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° C. under reduced pressure to obtain a polyurethane water dispersion 16 containing a cationic polyurethane resin (A16) having a nonvolatile content of about 35% by mass.

(Production Example 17: Cationic polyurethane resin (A17))

In a four-necked flask equipped with a stirrer, a reflux cooling tube, a thermometer, and a nitrogen blowing tube, add 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, N-methyldiethanolamine 30 parts by mass, hexamethylene diisocyanate 160 parts by mass, methyl 800 parts by mass of ethyl ketone was reacted at 75°C for 4 hours to obtain a methyl ethyl ketone solution of an amine ester prepolymer having a content of free isocyanate groups of 3.0% by mass relative to nonvolatile components. The solution was cooled to 40°C, and after adding 30 parts by mass of dimethyl sulfate, 2700 parts by mass of deionized water was slowly added for emulsification and dispersion. Thereafter, Tim An aqueous solution prepared 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° C. under reduced pressure to obtain a polyurethane aqueous dispersion 17 containing a cationic polyurethane resin (A17) having a nonvolatile content of about 35% by mass.

(Production Example 18: Cationic polyurethane resin (A18))

In a four-necked flask equipped with a stirrer, a reflux cooling tube, a thermometer, and a nitrogen blowing tube, 600 parts by mass of polyethylene glycol (PEG2000, manufactured by Sanyo Chemical Co., Ltd., Mw=2,000) and 30 parts by mass of N-methyldiethanolamine were added Parts, 80 parts by mass of hexamethylene diisocyanate, and 800 parts by mass of methyl ethyl ketone, which were reacted at 75° C. for 4 hours to obtain an amine ester preliminarily containing 3.0% by mass of free isocyanate groups relative to nonvolatile components. Polymer ethyl methyl ketone solution. The solution was cooled to 40°C, and after adding 30.2 parts by mass of dimethyl sulfate, 2700 parts by mass of deionized water was slowly added to emulsify and disperse. Thereafter, 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 under reduced pressure at 50° C. to obtain a polyurethane aqueous dispersion 18 containing a cationic polyurethane resin (A18) having a nonvolatile content of about 35% by mass.

Table 2 shows the phosphoric acid compound (B) used, and Table 3 shows the trivalent chromium compound (C) used.

4. Preparation of paint

The cationic polyurethane resin (A), phosphoric acid compound (B) and trivalent chromium compound (C) were mixed in order at the combinations and ratios shown in Table 4, and the solid content concentration was adjusted to 20% by mass with deionized water To prepare paint. Furthermore, the content ratio of the phosphoric acid compound (B) and the trivalent chromium compound (C) is the mass% of the solid content of the cationic polyurethane resin (A) (in other words, it means that each component is relative to the cationic polyurethane resin ( A) The content of 100 parts by mass (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 polyurethane resin (A) and the amine value.

5. How to make the test board

The coating material of the present invention was applied to each test material by a bar coater, and a heat treatment was performed at the limit plate temperature shown in Table 5, to form a film on each test material to manufacture a test plate. In addition, the amount of coating in each example is shown in Table 5, and the adjustment of the amount of coating is performed by adjusting the concentration of the paint (diluted with deionized water) and the number of the bar coater.

6. Evaluation method

(1) Appearance characteristics (film appearance)

Visually evaluate the appearance of the obtained test panel. ○The above is a practical level.

◎+: It is almost the same as the appearance of the plating, and almost no change after the film treatment

◎: Appearance is almost the same as plating, but depending on the visual angle, there are sometimes very few Uneven tones.

○: It is almost the same as the appearance of the plating, but there is little degree of uneven color tone.

△: There is a part different from the appearance of plating, and the part is thin white or yellow.

×: There are many parts that differ from the appearance of plating, and they are obviously white or yellow.

(2) Friction resistance (solvent resistance)

Ethanol was permeated into the gauze, and the surface of the film of the obtained test plate was subjected to a reciprocating friction test 20 times to observe the surface. △ Above is practical level.

◎+: No change in appearance

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

○: Slight change from frontal observation

△: Slightly changed from frontal observation (about half peeled off)

×: There is a change (approximately peeling off the entire surface)

(3) Corrosion resistance

Using the obtained test plate, a salt water spray test was performed based on JIS-Z-2371, and the area ratio of white rust generation after 24 hours was determined, and the evaluation was performed according to the following criteria. △ Above is practical level. Among them, 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%

◎: More than 5% and less than 10%

○+: more than 10% and less than 20%

○: More than 20% and less than 30%

△+: more than 30% and less than 40%

△: More than 40% and less than 50%

×: 50% or more

(4) Phosphate treatment (coated phosphate treatment)

The obtained test plate was treated with Palbond L15C (A agent 250g/L+B agent 250g/L, 25°C, brush painting), a chemical synthesis agent for phosphate treatment made by Parker Nasei Corporation, Japan Leave it for 5 minutes, observe the surface condition of the brushed part, and find the gray discoloration area ratio of the brushed part, and evaluate according to the following criteria. Furthermore, the higher the area ratio of gray discoloration, the more the film formed is partially dissolved by phosphate treatment, and the more the phosphate film is formed, the more grayish the hue is. △ Above is practical level.

◎+: 100%

◎: More than 95% and less than 100%

○: More than 85% and less than 95%

△: More than 70% and less than 85%

×: Less than 70%

(5) Adhesiveness of surface coating

A melamine alkyd resin coating material was applied to the coating film of the obtained test plate with a bar coater so that the dry film thickness became 25 μm, and baked at an oven temperature of 130° C. for 20 minutes to produce a coating film. Secondly, for the coating film, 100 grids with a width of 1 mm are implemented by a cutting machine, and are allowed to stand in a constant temperature storehouse at -20°C for more than 5 hours. The parts are processed by Erichsen. The tape peeling test of the processed part was carried out, and the peeling number of the grid was evaluated as follows. △ Above is practical level.

◎+: No stripping

◎: The number of peeling is more than 1 and less than 5

○: The number of peeling is more than 6 and less than 10

△: The number of peeling is more than 11 and less than 20

×: More than 20 peelings

(6) Impact resistance

A melamine alkyd resin coating material was applied to the coating film of the obtained test plate with a bar coater so that the dry film thickness became 25 μm, and baked at an oven temperature of 130° C. for 20 minutes to produce a coating film. Next, place the test plate with the coating film in a constant temperature store at 40°C for more than 5 hours. After removing the test plate, immediately use the DuPont impact tester. For the coating film, make the diameter 1/2 inch and 1 kg After the plumb fell from a height of 50 cm, the tape of the impact part was peeled off. The judgment is to find the remaining area ratio of the coating film. △ Above is practical level.

◎+: 100%

◎: More than 95% and less than 100%

○: More than 80% and less than 95%

△: More than 50% and less than 80%

×: less than 50%

(7) Storage stability of paint

According to the "period before gelation and precipitation occurred when the coating materials used in the examples and comparative examples were allowed to stand in a 40°C environment", the storage stability was evaluated as follows. △ Above is 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

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

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

In addition, according to the comparison between Example 26 and other examples (such as Example 25, etc.), it was confirmed that the peak temperature (Tg2) of the loss tangent tan δ is within a specific range (-50°C to -2°C) At this time, the adhesion of the surface coating is more excellent.

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

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

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

Claims (10)

A coating material for hot dip galvanized molten zinc plated steel sheet, comprising a cationic polyurethane resin having at least one cationic functional group selected from the group consisting of primary to tertiary amine groups and quaternary ammonium salt groups (A), the cationic polyurethane resin (A) has a polycarbonate structural unit and a bisphenol structural unit, and the temperature (Tg1) showing the maximum peak value of the loss elastic modulus E" of the cationic polyurethane resin (A) is In the range of -60°C to -5°C, the ratio of the loss elastic modulus E" to the storage elastic modulus E'of the cationic polyurethane resin (A), that is, the loss tangent tan δ, consists of a peak value. For example, the hot-dip galvanized hot-dip galvanized steel plate coating material of the first patent application, the peak temperature (Tg2) of the loss tangent tan δ is in the range of -50℃~-2℃. For example, the coating material for hot-dip galvanized hot-dip galvanized steel sheet according to item 1 or 2 of the patent application further contains a phosphoric acid compound (B). The coating material for hot-dip galvanized hot-dip galvanized steel sheet as claimed in item 3 of the patent application, wherein the phosphoric acid compound (B) contains at least one selected from the group consisting of orthophosphoric acid, condensed phosphoric acid and salts of these. For example, the coating for hot-dip galvanized molten zinc plated steel sheet according to item 1 or 2 of the patent application, wherein the cationic polyurethane resin (A) has an amine value (AV) of 2.0 to 5.0 mgKOH/g. The coating material for hot dip galvanized hot-dip galvanized steel sheet as claimed in item 5 of the patent scope, wherein the content ratio (mass%) of the phosphoric acid compound (B) to the solid content of the cationic polyurethane resin (A) (BV ) And the amine value ratio ((BV)/(AV)) is 0.1~9.5. For example, the paint for hot-dip galvanized steel sheet coating according to item 1 or 2 of the patent scope further contains a trivalent chromium compound (C). A treatment method for hot-dip galvanized hot-dip galvanized steel sheet, which uses the coating material for hot-dip galvanized hot-dip galvanized steel sheet according to any one of patent application items 1 to 7 to perform hot-dip hot-dip galvanized steel sheet treatment . A method for manufacturing a surface-treated hot-dip galvanized hot-dip galvanized steel sheet, which makes the hot-dip galvanized hot-dip galvanized steel sheet coating according to any one of claims 1 to 7 in contact with the hot-dip hot-dip galvanized steel sheet To manufacture a surface-treated hot-dip zinc-plated steel sheet having the hot-dip zinc-plated steel sheet and a film disposed on the surface. A surface-treated molten zinc plated steel sheet obtained by the manufacturing method of claim 9 of the patent application.