JPH06329980A - Resin composition for metal coating - Google Patents

Abstract

PURPOSE:To provide a resin compsn. which gives, when applied to a chemically pretreated galvanized or zinc-alloy-plated steel sheet, a coated steel sheet long retaining excellent adhesion, scratch resistance, rustproof properties, and lubricity and which can form a coating film useful also as an undercoating film. CONSTITUTION:The resin compsn. comprises a thermoplastic polyurethane resin, a copolyester resin, a bisphenol A epoxy resin, a wax, and, if necessary, a tetraalkoxysilane or its condensate. When applied to a metal substrate, esp. to a galvanized steel sheet, the compsn. forms a coating film which, even when it is very thin, greatly improves the formability and rustproofness of the sheet. Since the coating film is transparent, hardly allows a fingerprint to be left on it, is resistant to scratch during handling, and exhibits an excellent adhesive properties as an undercoating film, it is useful in various industries for rustproof treatment of chemically treated steel sheet.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition for metal coating, and particularly when it is coated on a galvanized or zinc-based alloy-plated steel sheet that has been subjected to a chemical conversion treatment, it has excellent adhesiveness for a long time. The present invention relates to a resin composition that has scratch resistance, rust prevention, and lubricity, and that forms a film that is effective as a coating base.
It is widely used in various industrial fields using metals such as the automobile industry.

[0002]

2. Description of the Related Art Conventionally, many treatment agents and paints have been used for the purpose of protecting the surface of galvanized steel sheet or galvanized steel sheet from various corrosive environments. Among them, phosphate treatment or chromate treatment is general. However, they have only a primary rust prevention role,
There is a problem that rust occurs in a short time, and even when it is premised on topcoating, it rusts during storage until then. In recent years, for the purpose of improving rust prevention, a steel sheet having a resin film formed on a zinc-plated steel sheet that has been subjected to chemical conversion treatment such as chromate treatment or phosphate treatment has been proposed and put into practical use. The properties required for such a steel sheet are scratch resistance during handling, fingerprint resistance, adhesion during molding, crack resistance, paintability during topcoating, adhesion and rust resistance,
In terms of durability such as water resistance, there are currently no proposals that have been proposed so far and that can sufficiently satisfy these required characteristics. Further, in recent years, from the viewpoint of energy saving, a composition for curing and forming a film at a lower temperature has been desired, but in a high-speed coating capable of taking a heating time of 20 to 120 seconds, the heat required for curing is inevitably required at a low temperature. Insufficient temperature is required, and the film must be cured to form a film at around 200 ° C., and especially in high-speed coating, low temperature is strongly required.

[0003]

An object of the present invention is to solve the above problems, and to provide a resin composition for metal coating having excellent properties.

[0004]

Means for Solving the Problems As a result of intensive studies for solving the above problems, the present inventors have found that they can be solved by a resin composition containing specific 4 or 5 components. The inventors have found out and completed the present invention.

That is, the present invention is an invention relating to a resin composition for metal coating characterized by containing the following components and a metal characterized by containing the following components and tetraalkoxysilane and / or a condensate thereof. It comprises two inventions, an invention relating to a resin composition for coating. A: Thermoplastic polyurethane resin B: Copolyester resin C: Bisphenol A type epoxy resin D: Wax

The composition of the present invention will be described in detail below. Thermoplastic polyurethane resin The thermoplastic polyurethane resin in the present invention comprises a soft block composed of a polyol and a diisocyanate produced by a reaction of a bifunctional polyol, a glycol and a diisocyanate, and a hard block composed of a glycol and a diisocyanate. Resin to be assembled, as the polyol component, polyester polyol, polyalkylene glycol, polycaprolactone polyol and the like, also, as the polyisocyanate component, toluene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, 4,4-diphenylmethane diisocyanate, 1, 5-Naphthylene diisocyanate, tolylene diisocyanate, xylylene diisocyanate, etc. Glycol, 1,4-butanediol, 1,6-hexanediol,
Examples thereof include bishydroxyethoxybenzene. Specific examples of the thermoplastic polyurethane resin include various commercially available products, for example, paraprene P22S, P26S (all manufactured by Nippon Polyurethane Co., Ltd.), Elastollan E-10.
80, E-1180, E-1095 (all manufactured by Nippon Elastollan Co., Ltd.), Pandex T-5201, TR
02, T-5265L, T-5205 (all manufactured by Dainippon Ink and Chemicals, Inc.), ESTANE5701, 57.
40 (above manufactured by BF Goodrich Co., Ltd.) and the like. Such a thermoplastic polyurethane resin is preferably soluble in a solvent such as tetrahydrofuran, cyclohexanone or methyl ethyl ketone, and has a number average molecular weight of 10,000 to 100,000 (converted to polystyrene) as measured by GPC. Number average molecular weight is 10,000
If it does not meet the requirements, the solvent resistance and adhesion of the overcoat after forming the coating film are poor, and if it exceeds 100,000, the viscosity when dissolved increases and the coating workability becomes poor. The amount of the thermoplastic polyurethane resin in the composition of the present invention is the total amount of the polyurethane resin A, the copolyester resin B and the bisphenol A type epoxy resin C constituting the composition of the present invention (hereinafter simply referred to as the total resin amount). Is preferably 10 to 90% by weight, more preferably 20 to 80% by weight. If it is less than 10% by weight, the corrosion resistance is lowered, and if it exceeds 90% by weight, the curability is lowered and the solvent resistance becomes insufficient.

Copolymerized polyester resin The copolymerized polyester resin used in the present invention includes:
Those widely used in the art as high molecular weight saturated polyester resins can be mentioned. Such a copolyester resin is synthesized by polycondensation of a dibasic acid and a dihydric alcohol, and examples of the dibasic acid include terephthalic acid, isophthalic acid, phthalic anhydride, and 2,8-naphthalenecarboxylic acid. Dibasic acids such as hexahydrophthalic acid, 1,4-cyclohexanedimethanol, etc .; Oxalic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, azelaic acid, dodecanedioic acid Aliphatic dibasic acids such as As such a dibasic acid,
A compound in which the carboxyl group is esterified with a monohydric alcohol may be used. For example, dimethyl terephthalate, dimethyl isophthalate, dimethyl adipate and the like. Further, as dihydric alcohol, ethylene glycol, 1,3-propylene glycol, 1,2-propylene glycol, 1,4-butanediol, 1,5-pentamethylene glycol, 1,6-hexanediol, 1,12 -Aliphatic dihydric alcohols such as dodecamethylene glycol, neopentyl glycol, diethylene glycol and triethylene glycol are used, and further, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, ethylene oxide adduct of bisphenol A, propylene oxide of bisphenol A. The thing using the alkylene oxide ring-opening polymer, such as an adduct, is also mentioned. Further, a hydroxycarboxylic acid such as p-oxybenzoic acid may be partially used in combination, and a compound having a trivalent or higher carboxylic group and / or a hydroxyl group, that is, trimellitic acid, pyromellitic acid and Its anhydride,
It is also possible to use those using trimethylolpropane, glycerin, pentaerythritol, etc., but the content of these trivalent or higher carboxylic acid components or trivalent or higher polyol components depends on the amount of dibasic acid or dihydric alcohol. On the other hand, it must be 5 mol% or less. The copolymerized polyester prepared in an amount of more than 5 mol% with respect to the acid or dihydric alcohol component has drawbacks such as poor solubility in a solvent and difficulty in obtaining a smooth coating film. The copolymerized polyester resin of the present invention preferably contains a terephthalic acid component in an amount of 20 to 80 mol% with respect to all acid components, and the other acid component is an aliphatic dibasic acid having 2 to 12 carbon atoms. Those composed of 60 mol% are preferred. Also,
The number average molecular weight of the copolyester resin is preferably 5,000 to 50,000 (in terms of polystyrene), more preferably 10,000, as measured by GPC.
~ 30,000. Number average molecular weight is 5,000
When it is less than 0, the processability and lubricity when formed into a film are poor, and when it is more than 50,000, the viscosity of the composition for coating becomes high and the solubility becomes poor, which is not preferable. . The polyester resin having a glass transition point of 50 ° C. or lower is preferable. If the glass transition point exceeds 50 ° C, the resin becomes hard and the coating film cracks,
Peeling easily occurs, which causes a problem in workability. The amount of copolymerized polyester resin in the composition of the present invention,
The total amount of the resin is preferably 10 to 60% by weight, more preferably 20 to 50% by weight. When it is less than 10% by weight, workability is deteriorated, and when it exceeds 60% by weight,
The low temperature curability becomes poor. As the reaction method for synthesizing polyester, a melt polymerization method in which only raw materials are charged and heated at a temperature equal to or higher than the melting point of the product, a solid-state polymerization method in which a reaction is performed at a temperature equal to or lower than the melting point of the product, and a solvent such as penzophenone is used. There are a solution polymerization method and an interfacial polymerization method using an acid chloride, and the copolyester of the present invention may be prepared by any method. The one prepared by the melt polymerization method is preferable from the viewpoints of obtaining an appropriate degree of polymerization which meets the object of the present invention and economical efficiency.

Bisphenol A type epoxy resin The bisphenol A type epoxy resin used in the present invention includes those produced by condensation of epichlorohydrin and bisphenol A. The epoxy resin is 1
It is an epoxy resin having two or more hydroxyl groups in the molecule and has a property of being solid at room temperature. Such an epoxy resin is a reaction condensate of epichlorohydrin and bisphenol A, and as a commercially available product, for example, Epicoat 10
01, 1002, 1004, 1007, 1009, 10
10 (above, manufactured by Yuka Shell Epoxy Co., Ltd.) and the like, and a phenoxy resin which is a high molecular weight bisphenol A type epoxy resin can also be used.
PKHH (made by Union Carbide Co.) and the like can be mentioned.
The compounding amount of the epoxy resin in the composition of the present invention is preferably 10 to 80% by weight, and more preferably 20 to 70% by weight based on the total amount of the resin. If it is less than 10% by weight, low-temperature curability is insufficient, and when it is formed into a coating film, problems such as poor adhesion of the topcoat occur. If it exceeds 80% by weight, the coating film is hard and flexible. And the workability and lubricity of the coating become insufficient.

Wax The wax used in the present invention is added for the purpose of exerting lubricity during molding such as bending, drawing and punching after coating and curing. Specific examples of the wax include paraffin wax, microcrystalline wax, montan wax, carnauba wax, bran wax, wood wax, beeswax, whale wax, lanolin, fatty acid amide wax, sazol wax, polyethylene wax and the like. The wax is not particularly limited, but microcrystalline wax and polyethylene wax are preferable. The wax having an acid value of 20 KOHmg / g or less is preferable. If the acid value exceeds this range, problems such as poor adhesion to the base steel sheet and peeling of the coating during processing will occur. The blending amount of the wax is preferably 1 to 50 parts by weight, more preferably 3 to 40 parts by weight, based on 100 parts by weight of the total resin. When it is less than 1 part by weight, the lubricity becomes insufficient, and when it exceeds 50 parts by weight, problems such as poor adhesion of the coating film and adhesion of the topcoat and peeling of the coating film during processing occur. .

Tetraalkoxysilane and its condensate The tetraalkoxysilane and its condensate used in the present invention are those obtained by hydrolyzing and condensing tetraalkoxysilane and tetraalkoxysilane with an acid catalyst and / or a base catalyst. As specific examples of the tetraalkoxysilane, there are tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, tetrabutoxysilane, tetrahydroxyethoxysilane and the like, and condensates thereof. Examples of commercial products of such tetraalkoxysilanes and condensates thereof include ethyl silicate 28, ethyl silicate 40 (manufactured by Nippon Corcoat Co., Ltd.), and methyl silicate 51 (manufactured by Tama Chemical Co., Ltd.). The compounding amount of tetraalkoxysilane and its condensate is 1 with respect to 100 parts by weight of the total resin.
Is preferably 50 to 50 parts by weight, more preferably 3 to 30 parts by weight. If the amount is less than 1 part by weight, the desired antirust property cannot be expected, and if the amount is more than 50 parts by weight, the coating becomes brittle and the physical properties of the coating become insufficient.

Curing Agent The resin composition of the present invention is usually used in combination with a curing agent such as a polyisocyanate resin or an amino resin, whereby a more dense cured film can be obtained. Examples of the polyisocyanate resin include blocked isocyanates. Blocked isocyanates are compounds obtained by blocking the isocyanate groups of polyisocyanates having two or more isocyanate groups with a blocking agent such as phenol, alcohol, caprolactam, or ketoxime.
By heating after coating, the blocking agent comes off, the isocyanate group is regenerated, and it reacts with the urethane resin. Examples of blocked isocyanates include commercially available dismodular CT and dismodular BL110.
0, dismodule BL3175 (above, Sumitomo Bayer Urethane Co., Ltd.), Coronate 2513, Coronate 2516, DC-2971 (Nippon Polyurethane Industry Co., Ltd.) Takenate B-830, Takenate B-8
00 (manufactured by Takeda Pharmaceutical Co., Ltd.) and the like. still,
When using blocked isocyanate as a curing agent,
In order to accelerate the dissociation of the blocked isocyanate and the reaction of the isocyanate, it is preferable to add a metal salt of an organic acid such as dibutyltin dilaurate or lead naphthenate, an organic amine compound such as diazabicycloundecene or a salt thereof. The compounding ratio of the polyisocyanate resin is preferably 5/95 to 70/30, more preferably 15/85 to 60 /, in terms of weight ratio with respect to the total amount of the resin.
When it is less than 5/95, the degree of curing is low and the durability of the coating becomes insufficient. When it exceeds 70/30, the proportion of the thermoplastic polyurethane resin is small and the coating is poor. It is not preferable because it may lack flexibility or adhesiveness. The amino resin as a curing agent is a thermosetting resin obtained by reacting one or more compounds selected from melamine, benzoguanamine, and urea with formaldehyde. Resin obtained by reacting such formaldehyde Some of the methylol groups therein are alkyl etherified. For example, as the methylated melamine resin, Cymel 300,
Cymel 370 (above, manufactured by Mitsui Toatsu Chemicals, Inc.), as methylated urea resin, Cymel 1123, UFR-6
5 (manufactured by Mitsui Toatsu Chemicals, Inc.), as butylated melamine resin, Uban 10S-60, Uban 20SE-6
0, Uban 134, Uban 62 (above, manufactured by Mitsui Toatsu Chemicals, Inc.), Super Beckamine L-117-6
0, Super Beckamine L-109-65, Super Beckamine L-145-60 (above, Dainippon Ink and Chemicals, Inc.) etc. are mentioned. There is no reason to use a particularly limited amino resin used in the present invention, but a butylated melamine resin is preferably selected in terms of the balance between curability and coating film performance after curing.
When using an amino resin as a curing agent, para-toluenesulfonic acid, in order to accelerate the reaction of the amino resin,
A catalyst such as an organic sulfonic acid such as naphthalene sulfonic acid and / or a salt thereof can also be added. The weight ratio of the amino resin to the total amount of the resin is 5 / 95-6.
It is preferably 0/40, more preferably 15
/ 85 to 40/60, and when it is less than 5/95, the degree of curing is low and the durability of the film is insufficient.
If it exceeds the range, the ratio of the thermoplastic polyurethane resin is small, so that the film may lack flexibility or adhesiveness, which is not preferable.

Solvent The composition of the present invention is generally applied in a liquid state, and when it is used by dissolving it in a solvent, more excellent effects are exhibited. As the solvent used, for example,
Aromatic solvents such as toluene, xylene, ethylbenzene, mesitylene; acetone, methyl ethyl ketone, methyl isobutyl ketone, dibutyl ketone, cyclohexanone,
Monoketone solvents such as isophorone; acetylacetone,
1,3-diketone solvents such as methyl acetoacetate and ethyl acetoacetate and β-ketocarboxylic acid ester solvents; methyl alcohol, ethyl alcohol, isopropyl alcohol, isobutyl alcohol, n-butyl alcohol, 3-methoxybutyl alcohol, 3- Alcoholic solvents such as methyl-3-methoxybutyl alcohol; glycol monoethers such as ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol butyl ether, diethylene glycol ethyl ether, propylene glycol methyl ether, propylene glycol ethyl ether, propylene glycol butyl ether Solvents: ethyl acetate, butyl acetate, ethylene glycol methyl ether acetate, propylene glycol methyl ether acetate, professional Examples include ester solvents such as pyrene glycol ethyl ether acetate, dimethyl adipate and ethyl 2-ethoxypropionate; and tetrahydrofuran, 2-methylpyrrolidone and the like. The solvent to be used is not particularly limited, but it is preferable to use a mixed solvent of two or more selected from ketone type, aromatic type, glycol ether, glycol ether acetate type, which have good dissolving power. ,
More preferably, the boiling point at atmospheric pressure is 100 ° C. or higher and 220.
A solvent having a temperature of not higher than 0 ° C. has an appropriate volatilization rate and is preferable in terms of drying property. The concentration of the non-volatile component in the case of a solution is preferably 3 to 80% by weight, more preferably 5 to 50% by weight. If the ratio is out of this range, the liquid viscosity at the time of coating becomes unsuitable, and the coating film after coating becomes defective.

Additives In addition to the above components, the composition of the present invention may contain appropriate additives for various purposes. Examples of such additives include those widely used in the field, and examples thereof are given below. Black pigments such as carbon black, acetylene black, rum black, bone black and black iron oxide; white pigments such as titanium oxide, zinc white, and lead white; anticorrosion pigments such as zinc dichromate and strontium dichromate; carbonic acid Extender pigments such as calcium, talc, clay, kaolin, alumina and silicic acid anhydride; metal powders such as zinc powder and aluminum powder; other additives such as molybdenum disulfide, ethylene tetrafluoride powder and vinylidene fluoride powder. Others, viscosity modifiers, defoamers, leveling agents,
Various additives such as a siloxane bond condensation catalyst, an antioxidant and an ultraviolet absorber may be added. Such additives can be added at an appropriate stage during production.

Preparation Method The composition of the present invention may be prepared by dissolving or uniformly dissolving a thermoplastic polyurethane resin, a copolyester resin, a bisphenol A type epoxy resin and a blocked isocyanate and / or amino resin used as a curing agent. Any method can be used as long as it can be dispersed, and a known mixing method can be adopted. For example, it is prepared by the following method.
Thermoplastic polyurethane resin, copolyester resin,
Examples include a method in which a solution of a bisphenol A type epoxy resin dissolved in a solvent as needed and a blocked isocyanate and / or an amino resin are simply stirred and mixed with a suitable stirring device. At that time, if necessary, 60 to 200 ° C. Heat to. The nonvolatile concentration is preferably 3 to 80 as described above.
It is prepared so that the weight percentage is more preferably 5 to 50 wt%.

○ Applicable substrate The composition of the present invention can be widely applied to a metal substrate, but iron and iron alloys, aluminum and aluminum alloys, copper and copper alloys, zinc plating and zinc alloy plating, nickel plating, It is best used for base materials that have been plated with various plating such as chrome plating and cadmium plating. In particular, zinc plating, nickel / zinc plating, iron / zinc plating, tin It exhibits excellent anticorrosion performance against zinc and zinc alloy plating such as zinc plating, and on metals whose surfaces are chromate-treated or phosphate-treated.

○ Application Method The composition of the present invention in a solution form can be easily applied to a metal substrate, and as a method therefor, known coating methods such as spray coating, dip coating, roll coating and brush coating can be applied. . After coating, the solvent can be removed at room temperature or under heating conditions to form a uniform coating film, thereby achieving the object of the present invention. It is preferable to apply approximately 0.1 to 100 g / m ² as a film thickness, more preferably 0.3 to 30 g / m ^2, particularly preferably ^{0.6~10g / m 2, 10g / m} 2 or less It is a great feature of the composition of the present invention that even if the film thickness is 1, the rust preventive property and lubricity can be remarkably imparted thereby. Further, the metal treated with the composition of the present invention can be used as it is, but it is also possible to top coat various paints such as solvent-based, water-based, solvent-free, and powder-based paints. As the coating method, spray coating, roll coating, dip coating, electrostatic coating, electrodeposition coating, etc. can be used, and it is dried by methods such as room temperature curing, hot air heating, high frequency heating, far infrared heating, ultraviolet irradiation, and electron beam irradiation. , Cured. Examples of such coatings include undercoating / topcoating of precoated steel sheets that are heavily used in the field of building materials and home appliances, topcoating used in the field of home appliances, electrodeposition coating / intermediate coating / topcoating in the field of automobiles, civil engineering, etc.・ Steel pipes / painting used in construction can be mentioned.

[0017]

The composition of the present invention comprises a thermoplastic polyurethane resin,
It is composed of a copolyester resin, a bisphenol A type epoxy resin and a wax, and the curing mechanism by a curing agent is not clear, but the effects of the composition of the present invention are presumed to be due to the following mechanism. The high molecular weight thermoplastic polyurethane resin and the polyester resin component have flexibility, and the epoxy resin firmly adheres to the metal substrate to form a film having appropriate flexibility, and the resin is dispersed in the film. The wax gives lubricity and processability. In the curing reaction after coating, a polyester resin having an OH group, a thermoplastic polyurethane resin, and a bisphenol A type epoxy resin are combined with an appropriate curing agent to form a coating having a complicatedly entangled structure. By blending tetraalkoxysilane and / or its condensate into the composition, it reacts with the hydroxyl groups of the resin and imparts a highly crosslinked coating structure. Further, the tetraalkoxysilane and / or its condensate has adhesiveness with the metal base material and exhibits functions such as corrosion resistance.

The present invention will be described below with reference to specific examples (parts by weight are hereinafter referred to as parts). ○ Synthesis of Copolymerized Polyester Resin A In a four-necked flask equipped with a nitrogen inlet tube, a distillation tube, a thermometer, and a stirrer, 77.7 parts of dimethyl terephthalic acid, 83.4 parts of neopentyl glycol, and 74. parts of ethylene glycol. Five
Parts, 0.1 part of zinc acetate, the temperature was raised while introducing nitrogen, and methanol was distilled off at 150 to 200 ° C., then 49.8 parts of isophthalic acid, 58.4 parts of adipic acid, and antimony trioxide. After additionally charging 0.1 part, water was distilled off at 200 to 250 ° C. 1mmHg at 250 ℃ while gradually reducing pressure
The vacuum was continued for 3 hours. The obtained copolyester resin A is a light yellow transparent solid having a number average molecular weight of 15,000 (polystyrene equivalent in GPC), and NM
As a result of R analysis, the molar ratio of the acid component was terephthalic acid / isophthalic acid / adipic acid = 40/20/40, and the molar ratio of the dihydric alcohol component was ethylene glycol / neopentyl glycol = 50/50.

Synthesis of Copolymerized Polyester Resins B to C In the same manner as the copolymerized polyester resin A, the copolymerized polyester resin having a composition in which the molar ratio of the acid component and the dihydric alcohol component of the final copolymerized polyester resin is shown in Table 1 Was synthesized.

[0020]

[Table 1]

[0021]

【Example】

Example 1 Polyurethane resin Paraprene 22S (manufactured by Nippon Polyurethane Industry Co., Ltd.) 25 parts, copolymer polyester resin A 25 parts prepared as described above, bisphenol A type epoxy resin Epicoat 1007 (manufactured by Yuka Shell Epoxy Co., Ltd.) 50 parts, blocked isocyanate Coronate 250
7 (80% by weight of nonvolatile content, manufactured by Nippon Polyurethane Industry Co., Ltd.) 50 parts by weight of cyclohexanone / xylene = 7/3
Polyethylene wax AC-polyerylene (manufactured by Allied Signal) 10 dissolved in a mixed solvent (weight ratio)
The parts were dispersed. 0.1 part of paratoluenesulfonic acid was added to the obtained dispersion liquid to prepare a solution having a nonvolatile content of 20% by weight. This resin composition was subjected to the following tests, and the results are shown in Table 4.

Preparation of test plate Electrogalvanized electrolytic chromate treated plate (70 × 150 ×
This solution was applied to a film thickness of 1 g / m ² with a bar coater (0.475 mmt) and heat-treated (maximum plate temperature 200 ° C. ×).
60 seconds). Bending test A test plate was bent 180 degrees around a cylinder, and then the test plate was sandwiched and clamped with a vise. The bent part is adhered and peeled off with a piece of cellophane tape, and the presence or absence of cracks and peeling is examined with a microscope (20x).
The number of test plates at the time of passing was displayed, and the following scores were given. ◎: OT ○: 1T, 2T △: 3T, 4T ×: 5T or more ○ Corrosion resistance test A salt spray test (JI
S-Z-2317) It carried out for 240 hours and evaluated. As a comparison, the uncoated product was also tested, but after 240 hours, red rust had occurred. The evaluation criteria are as follows. ○: No rust generation △: White rust 2 mm or less ×: White rust 2 mm or more Further, as a corrosion resistance test after processing, after performing Erichsen 7 mm extrusion (JIS-K-5400) on the test plate, a salt spray test (JIS- Z-2371) It carried out for 240 hours. The evaluation criteria are as follows. ○: No rust rusting △: White rust less than 10% of the processed area area ×: White rust of 10% or more of the processed area area ○ Adhesion test Adhesion test is the primary adhesion and secondary adhesion Was tested.
The primary adhesion test is 100 at 1 mm intervals on each test plate coating surface.
This is done by notching individual gougin and adhering / peeling an adhesive tape to this goban. The secondary adhesion test is
After coating, soak each test plate in warm water (pure water) at 40 ° C for 240 hours and then remove it.
It was carried out by making notches at intervals and adhering / peeling an adhesive tape to the notches. In addition, the adhesion of the top coat is based on Amylak # 8 manufactured by Kansai Paint Co., Ltd.
After applying 05μ of 40μ, the same primary adhesion and 2
Subsequent adhesion was tested. ◯: No peeling Δ: Peeling 10% or less X: Peeling 10% or more ○ Cylindrical deep drawing test The test plate was subjected to cylindrical cup drawing under the following conditions, and the limiting drawing ratio was determined. Press conditions ・ Wrinkle presser pressure 10KgN ・ Punch diameter 33mmφ ・ Drawing speed 20mm / sec The following rating was given according to the limiting drawing ratio. ◎: 2.39 or more ○: 2.36 or more and less than 2.39 △: 2.33 or more and less than 2.36 ×: Less than 2.33 ○ Solvent resistance test Cotton is dipped in xylene and rubbed before and after. The state of the coating film was evaluated and the following scores were given. ◯: No change 50 times or more Δ: Coating defect is 20 times or more and less than 50 times ×: Coating defect is less than 20 times

Examples 2 to 23 Polyurethane resins, epoxy resins, copolyester resins, curing agents (amino resins or blocked isocyanate resins), waxes, tetraalkoxys shown in Tables 2 and 3 were prepared in the same manner as in Example 1. A 20% strength by weight solution of the composition using orchid and / or its condensate was obtained. These resin compositions were tested in the same manner as in Example 1 and the results are summarized in Tables 4 and 5. The details of the various components used in Tables 2 and 3 are as follows. * 1 Polyester-based polyurethane resin Symbol Product name Manufacturer A Paraprene 22S Nippon Polyurethane Industry Co., Ltd. B Paraprene 26S Nippon Polyurethane Industry Co., Ltd. C Bandex T-5205 Dainippon Ink Industries Co., Ltd. D Bandex T-R02 Dainippon Ink Industries Co., Ltd. E Elastron E-1080 Nippon Elastron Co., Ltd. F Elastron E-1180 Japan Elastron Co., Ltd. * 2 Epoxy resin symbol Product name Manufacturer A Epicoat 1007 Yuka Shell Epoxy Co., Ltd. B Epicoat 1004 Yuka Shell Epoxy Co., Ltd. C Epicoat 828 Yuka Shell Epoxy Co., Ltd. D PKHH Union Carbide Co., Ltd. * 3 Copolyester resin The above synthetic product was used. * 4 Curing agent Symbol Product name Manufacturer A Coronate 2507 Nippon Polyurethane Industry Co., Ltd. B Coronate 2513 Nippon Polyurethane Industry Co., Ltd. C Dismodule BL-3175 Sumitomo Bayer Urethane Co., Ltd. D Uvan 122 Mitsui Toatsu Chemicals, Inc. E Cymel 300 Mitsui Higashi Pressure Chemical Industry Co., Ltd. * 5 Wax symbol Product name Manufacturer A POLYMIST A-12 Allied Signal Co., Ltd. B High Wax 100P Mitsui Petrochemical Co., Ltd. C High Wax 2203A Mitsui Petrochemical Co., Ltd. * 6 Tetraethoxysilane and its condensation Product symbol Product name Manufacturer A Tetraethoxysilane Tama Chemical Co., Ltd. B Methyl silicate 51 Tama Chemical Co., Ltd. C Ethyl silicate 40 Tama Chemical Co., Ltd.

Comparative Examples 1 to 7 By the same method as in Example 1, polyurethane resin, epoxy resin, copolymerized polyester resin, curing agent (amino resin or blocked isocyanate resin) shown in Table 3,
A resin composition solution having a concentration of 20% by weight was obtained using wax, tetraalkoxylane and / or its condensate. These resin compositions were tested in the same manner as in Example 1, and the results are summarized in Table 5.

[0025]

[Table 2]

[0026]

[Table 3]

[0027]

[Table 4]

[0028]

[Table 5]

[0029]

[Effect] When the composition of the present invention is applied to a metal substrate, particularly a galvanized steel sheet and formed into a film, even if the film thickness is 5 g / m ² or less, the workability and the processability can be improved. The coating is transparent and has strong resistance to fingerprint marks and scratches during various handling, and also has excellent adhesion as a coating base when coated on it. As a rust preventive treatment after chemical conversion treatment of a steel sheet, it can widely contribute to various industries.

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Claims (2)

[Claims] 1. A resin composition for metal coating, comprising the following components. A: Thermoplastic polyurethane resin B: Copolyester resin C: Bisphenol A type epoxy resin D: Wax 2. The resin composition for metal coating according to claim 1, further comprising tetraalkoxysilane and / or a condensate thereof.