JP2002326310A - Resin coated metal panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin coated metal panel having a resin film excellent not only in corrosion resistance but also in various characteristics such as coating properties, lubricity, processability, earthing properties or the like and well-balanced between these characteristics. SOLUTION: The resin coated metal panel has the resin film formed from an emulsified resin composition comprising an ethylene/unsaturated carboxylic acid copolymer and an amino-alcohol represented by formul (1) (wherein, 1-3 groups among X, Y and Z are each a group wherein 1-10 mole of 2-4C alkylene oxides are connected and the terminals thereof are hydroxyl groups through an alkylene oxide residue and 0-2 residual groups among them are each a lower alkyl group) contained in an amount of 0.1-10 mass % with respect to the ethylene/unsaturated carboxylic acid copolymer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin-coated metal sheet having excellent corrosion resistance which can be suitably used for home electric appliances and building materials.

[0002]

2. Description of the Related Art Conventionally, as a metal plate used for household electric appliances and building materials, aluminum-plated and stainless steel plates, surface-treated steel plates such as electrogalvanized steel plates and hot-dip galvanized steel plates have been widely used. . Among them, zinc-plated surface-treated steel sheets that have been conventionally subjected to chromate treatment or phosphate treatment or organic resin-coated steel sheets are mainly used in household electrical products, such as audio equipment, computer parts, and microwave ovens. Widely used for various members such as a bottom plate. However, in recent years, user needs for these surface-treated steel sheets have become increasingly sophisticated, and various kinds of film performance have been required.

For example, when a surface-treated steel sheet is barely used, it is required to have corrosion resistance, grounding property, fingerprint resistance that is inconspicuous even when fingerprints adhere thereto, chemical resistance to alkalis and solvents, contamination resistance, and the like. You. In the case of pressing or punching, lubrication, scratch resistance, deep drawing,
Die wear resistance, punching resistance, blackening resistance of the working sliding surface, oil resistance of press oil, quick drying oil, etc. are required.

In order to satisfy such various required characteristics, many resin-coated steel sheets having an organic resin film as shown below have been proposed. For example, JP-A-62-50480 discloses that after a galvanized steel sheet is chromate-treated,
A galvanized steel sheet composed of a carboxylated polyolefin resin and an epoxy resin and forming an organic film containing colloidal silica to improve corrosion resistance, paintability, solvent resistance, alkali resistance and fingerprint resistance Is described. JP-A 64-73083 discloses ethylene-α, β containing a colloidal sol of a metal oxide.
-In a dispersion of an unsaturated carboxylic acid copolymer, a polymerizable ethylenically unsaturated compound is emulsion-polymerized, and after the polymerization is completed, a treatment liquid in which the polymer is crosslinked using a carboxyl group is further prepared. Is applied to a galvanized steel sheet that has been subjected to chromate treatment, and adhesion, fingerprint resistance, coin scratch resistance,
A surface-treated steel sheet with improved corrosion resistance and the like is described.

[0005] Japanese Patent Publication No. 5-54823 discloses that after a galvanized steel sheet is subjected to a chromate treatment, a resin liquid comprising an ethylene-unsaturated carboxylic acid copolymer containing colloidal silica and an organic substance having an aziridinyl group is applied and dried. It is described that by forming a crosslinked film in this manner, a resin-coated metal plate having improved paintability, corrosion resistance, chemical resistance, and scratch resistance can be obtained.

JP-A-6-246229 discloses that a galvanized steel sheet is subjected to a chromate treatment, and ethylene and α, β
-Maintaining good corrosion resistance by forming a resin film composed of an ethylene ionomer resin having ethylenically unsaturated carboxylic acid as a main chain component and neutralizing 60 to 80% by mass of carboxyl groups with sodium ions, It is described that an organic composite coated steel sheet having improved blackening resistance is obtained.

According to these prior arts, corrosion resistance, paintability, fingerprint resistance, chemical resistance, stain resistance, lubricity, scratch resistance, deep drawing workability, mold wear resistance, and working sliding surface Properties such as blackening resistance, oil resistance, and grounding properties have been improved to some extent. However, more recently, organic resin coatings have been applied to the organic resin film due to the desire to omit the post-coating process for cost reduction and the movement of chromium-free (preventing the chromate treatment) for global environmental protection. On the other hand, more corrosion resistance is required.

[0008]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems in conventional resin-coated metal sheets, particularly in resin-coated steel sheets, and not only has excellent corrosion resistance but also has excellent corrosion resistance. The object of the present invention was to provide a resin-coated metal plate having a resin film having excellent properties such as paintability, lubricity, workability, and grounding property, and having a good balance of these properties.

[0009]

The resin-coated metal plate of the present invention comprises an ethylene-unsaturated carboxylic acid copolymer and an amino alcohol represented by the following general formula (1). The gist lies in providing a resin film formed from an emulsified resin composition containing 0.1 to 10% by mass with respect to the coalescence.

[0010]

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(However, 1 to 3 moles of X, Y and Z are linked by 1 to 10 moles of a C2 to C4 alkylene oxide, and the terminal is a hydroxyl group via the alkylene oxide residue.) And the remaining 0 to 2 are lower alkyl groups.)

A resin film is formed on the surface of a metal plate using an emulsified resin composition obtained by emulsifying an ethylene-unsaturated carboxylic acid copolymer by using a specific amount of the above specific amino alcohol, thereby obtaining a corrosion resistance. Could be improved.

The above-mentioned ethylene-unsaturated carboxylic acid copolymer is preferably obtained by copolymerizing 1 to 40% by mass of an unsaturated carboxylic acid. If the amount of the unsaturated carboxylic acid is in this range, the emulsifying dispersibility and the corrosion resistance are good.

The above emulsified resin composition may further comprise a carboxyl-modified urethane resin and at least one metal compound for crosslinking selected from the group consisting of metal carbonates, metal hydroxides and metal oxides. This is a preferred embodiment of the present invention. This is because the carboxyl group of the ethylene-unsaturated carboxylic acid copolymer and / or the carboxyl group of the carboxyl-modified urethane resin are cross-linked by the metal compound for cross-linking, and a resin film having good properties can be obtained. In this respect, the acid value of the carboxyl-modified urethane resin is preferably from 3 to 155, and the metal compound for crosslinking is preferably a compound of a divalent or higher-valent metal element. In order to exhibit the above effects, the carboxyl-modified urethane resin is preferably contained in the emulsified resin composition in an amount of 5 to 80% by mass based on the ethylene-unsaturated carboxylic acid copolymer.

When the aziridine compound is contained in an amount of 1 to 20% by mass in 100% by mass of the solid content of the emulsified resin composition, the carboxyl group of the ethylene-unsaturated carboxylic acid copolymer or the carboxyl group-modified urethane resin is crosslinked. Therefore, the physical properties of the resin film are further improved.

In order to improve the corrosion resistance and lubricity, the emulsion resin composition has an average particle diameter of 1 to 20 in 100% by mass of the solid content.
0 to 30% by mass of 0 nm silica particles may be contained. Further, in 100% by mass of the solid content of the emulsified resin composition,
When the wax content is 0.5 to 10% by mass, the lubricity is further improved, and in particular, a substantially spherical polyethylene wax having an average particle diameter of 0.1 to 3 μm can be preferably used. In addition, in order to exhibit corrosion resistance and other characteristics, it is preferable that the adhesion amount of the resin film is 0.2 to 2.5 g / m ² .

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The resin-coated metal plate of the present invention is provided with a resin film formed from a specific emulsified resin composition on at least one surface of the metal plate. As a metal plate,
Although not particularly limited, examples thereof include zinc or galvanized steel sheet, aluminum sheet, aluminum alloy sheet, and titanium sheet. Further, these metal plates may be subjected to a known rust-preventive base treatment such as a phosphate treatment or other base treatment, and a resin film may be formed thereon. From the viewpoint of environmental problems, it is preferable not to perform the chromate treatment.

The emulsified resin composition used in the present invention for forming a resin film contains ethylene-ethylene as an essential component.
It contains an unsaturated carboxylic acid copolymer. This ethylene-unsaturated carboxylic acid copolymer is a copolymer of ethylene and an ethylenically unsaturated carboxylic acid. Examples of the unsaturated carboxylic acid include (meth) acrylic acid, crotonic acid, isocrotonic acid, maleic acid, fumaric acid, and itaconic acid, and one or more of these, and ethylene,
By polymerizing by emulsion polymerization method or high temperature and high pressure polymerization method,
A copolymer can be obtained. The copolymer is most preferably random, but may be a block copolymer or a copolymer in which an unsaturated carboxylic acid moiety is grafted.

Preferred copolymer ratios of ethylene and unsaturated carboxylic acid are 60 to 99% by weight of ethylene and 1 to 40% by weight of unsaturated carboxylic acid. If the amount of unsaturated carboxylic acid is less than 1% by mass, the number of functional groups is too small to achieve the object of the present invention, and the emulsion stability for environmental protection is poor. A more preferred lower limit of the unsaturated carboxylic acid is 8% by mass. On the other hand, when the unsaturated carboxylic acid is 4
If it exceeds 0% by mass, the corrosion resistance and water resistance of the resin film are inferior, and the blocking property is so strong that handling becomes difficult. A more preferred upper limit is 30% by mass.
It is. The most preferred unsaturated carboxylic acid is (meth) acrylic acid. Further, an olefin-based monomer such as propylene or 1-butene may be used instead of part of ethylene, and other known vinyl-based monomers may be partially copolymerized as long as the object of the present invention is not impaired. May be.

The emulsified resin composition of the present invention further contains an amino alcohol represented by the following general formula (1) as an essential component.

[0021]

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(However, 1 to 3 of X, Y and Z are linked by 1 to 10 moles of a C2 to C4 alkylene oxide, and the terminal is a hydroxyl group via the alkylene oxide residue.) And the remaining 0 to 2 are lower alkyl groups.)

The amino alcohol is obtained by reacting an alkylamine with one or more of a C2 to C4 alkylene oxide, ie, one or more of ethylene oxide, propylene oxide, and butylene oxide. A group whose terminal is a hydroxyl group is formed via the group. X, Y, Z
At least one of them must be a terminal hydroxyl group having such a long side chain, and two or all three may be this group. Due to the presence of this group, the ethylene-unsaturated carboxylic acid copolymer has a thickness of 5 nm to
It could be emulsified into fine particles of 0.5 μm level, and the drying property and film forming property of the emulsified resin composition could be improved. Furthermore, the corrosion resistance and lubricity of the resin film could be improved in a well-balanced manner.

The number of moles of alkylene oxide added is 1 to 10 moles on average, and if added in excess of 10 moles, the fineness of the particles becomes insufficient, and the above effect is not exhibited. A more preferred number of moles of the added alkylene oxide is 2 to 10 mol or more. When the group whose terminal is a hydroxyl group via an alkylene oxide residue is one or two of X, Y and Z, the group other than this group has 1 carbon atom derived from the alkyl group of the alkylamine. ~ 6 lower alkyl groups.

Specific examples of the amino alcohol represented by the above general formula (1) include triethanolamine, N-methyldiethanolamine, N, N-dimethylethanolamine, N, N-diethylethanolamine, N, N-
Dibutylethanolamine, N-methylpolyalkanolamine, N-ethylpolyalkanolamine, N, N
-Dimethylpolyalkanolamine, N, N-diethylpolyalkanolamine and the like. In addition, "polyalkanol" of (alkyl) polyalkanolamine
The expression means that one or more of ethylene oxide, propylene oxide, and butylene oxide are added to the alkylamine in a total amount of 3 to 10 mol or more. Among the above-mentioned amino alcohols, N-methyldiethanolamine and (alkyl) polyalkanolamine are preferable from the viewpoint of forming fine particles.

The above amino alcohol is represented by the following formula when the ethylene-unsaturated carboxylic acid copolymer is 100% by mass.
It is preferable to use 0.1 to 10% by mass because the copolymer can be finely divided, the film forming property, the corrosion resistance, water resistance, adhesion and the like of the obtained resin film can be obtained in a well-balanced manner. If the amount is less than 0.1% by mass, the fine particles are insufficiently formed, the film-forming properties and adhesion are reduced, and the effect of improving the corrosion resistance is not exhibited.
Exceeding the range is not preferred because the water resistance and the like decrease.

The ethylene-unsaturated carboxylic acid copolymer has a low carboxyl group content or a high molecular weight,
When the emulsion stability is insufficient with the amino alcohol alone, a known surfactant, known alkalis such as sodium hydroxide, and amines such as ammonia and triethylamine may be used in combination. From the viewpoint of the water resistance of the resin film, alkalis and / or ammonia / amines are preferable to surfactants.

The emulsified resin composition used in the present invention includes:
Further, it is preferable that the carboxyl-modified urethane resin is contained in an emulsified state. It is preferable to use a carboxyl-modified urethane resin in combination, because it has excellent compatibility with an ethylene-unsaturated carboxylic acid copolymer, and a resin film composed of these blends has an ethylene-unsaturated carboxylic acid copolymer. This is because the corrosion resistance, workability, scratch resistance, and the like of the urethane resin are improved without impairing the performance such as water resistance, chemical resistance, and lubricity. Urethane resins also have the advantage that a variety of molecular designs can be made and a wide range of physical properties can be adjusted. Carboxyl modification is performed to impart emulsifying ability and to crosslink with a carboxyl group of an ethylene-unsaturated carboxylic acid copolymer by a metal compound described later to further improve the strength of the resin film and corrosion resistance. is there.

As the degree of carboxyl modification, the acid value is preferably 3 to 155 mgKOH / g. When the acid value is 3 mgKOH / g or less, the emulsion stability is poor, and the intended modifying effect may be insufficient. 155
If it exceeds mgKOH, the resulting resin film will have poor water resistance and chemical resistance.

In the emulsified resin composition used in the present invention, the carboxyl-modified urethane resin accounts for 5 to 80% by mass based on 100% by mass of the ethylene-unsaturated carboxylic acid copolymer.
Preferably, it is included. If less than 5% by mass,
It may be difficult to obtain the desired modifying effect, and the workability and corrosion resistance may not be sufficiently exhibited. Addition of more than 80% by mass is not preferred because the particle size distribution of the whole emulsified resin composition becomes wide, and the effects of using the amino alcohol to make fine particles and improve the film-forming property become inconspicuous.

As the carboxyl-modified urethane resin, a urethane prepolymer having a terminal isocyanate is obtained from a known polyol component and polyisocyanate component, and a compound having both a hydroxyl group and a carboxyl group, for example, dimethylol such as dimethylolpropionic acid. Is reacted to obtain a prepolymer having a carboxyl group, and it is possible to obtain a carboxyl-modified urethane resin emulsion as it is or by extending the chain with an amine or the like and emulsifying the prepolymer.

In addition, as long as the object of the present invention is not impaired, other resin emulsions such as synthetic rubbers, acrylics and styrenes can be used in place of a part of the urethane resin. In this case, it is preferable that these other resin emulsions also have a carboxyl group.

Since both the ethylene-unsaturated carboxylic acid copolymer and the carboxyl-modified urethane resin have a carboxyl group, they are cross-linked by metal ions. It is preferable to add at least one member selected from the group consisting of a substance and a metal oxide. Various properties such as corrosion resistance and scratch resistance of the resin film can be improved by ionic crosslinking. Further, even when a carboxyl-modified urethane resin is not used in combination, the use of these metal compounds is preferable because the ethylene-unsaturated carboxylic acid copolymer is ionized. The amount of the metal compound for cross-linking is such that the metal atom is 0.01 to 0.10 equivalent to 1 equivalent of the carboxyl group of the ethylene-unsaturated carboxylic acid copolymer and the carboxyl-modified urethane resin. Is preferred. If the amount is less than 0.01 equivalent, the crosslinking reaction with the carboxyl group becomes insufficient and the water resistance of the resin film is reduced. In addition, the resin film becomes hydrophilic with monovalent metals such as Na ions and K ions in the alkaline compound used in the degreasing step for the post-coating, resulting in a disadvantage that the corrosion resistance and the coating property are reduced. On the other hand, 0.1
If the amount is more than the equivalent, the crosslinking density of the resin film becomes excessively high, the hardness increases, and it becomes impossible to follow the deformation at the time of press working.

Specifically, Ba, Fe, Ca, Mg, C
B, made on the basis of a divalent metal such as u, Zn, Mn, etc.
_{aCO 3, FeCO 3, CaCO 3} , MgCO 3, CuCO
₃ , metal carbonates such as ZnCO ₃ , Ba (OH) ₂ ,
Fe (OH) ₂ , Fe (OH) ₃ , Ca (OH) ₂ , Mg
(OH) ₂ , metal hydroxides such as Zn (OH) ₂ , CaO,
Metal oxides such as MgO and ZnO are mentioned. These are selected and used as needed, and are used in combination.

Other examples of calcium compounds include:
Calcium lactate, calcium stearate, calcium carboxymethylcellulose, calcium stearoyl lactate, calcium propionate, calcium citrate,
Calcium glycerophosphate, calcium gluconate, calcium dihydrogen pyrophosphate, calcium monohydrogen phosphate,
Organic acid calcium salts such as calcium dihydrogen phosphate and tricalcium phosphate can be used in combination as needed, and the same applies to other metal systems.

A crosslinking agent having an aziridinyl group, which is a functional group capable of reacting with a carboxyl group, may be added to the emulsion resin composition. In order to work as a cross-linking agent, it is preferable that the molecule has an average of 1.5 to 3.5 aziridinyl groups, and specifically, N, N'-hexamethylene-1,6- Bifunctional aziridine compounds such as bis (1-aziridinecarboxamide), N, N'-diphenylmethane-4,4'-bis (1-aziridinecarboxamide), toluenebisaziridinecarboxamide; tri-1-aziridinylphosphine Examples thereof include trifunctional or higher functional aziridine compounds such as oxide, trimethylolpropane tri (β-aziridinylpropionate), and tetramethylpropanetetraaziridinylpropionate, and derivatives thereof. These polyfunctional aziridines may be used in combination with monofunctional aziridines (such as ethyleneimine).

The aziridine compound is preferably contained in an amount of 1 to 20% by mass based on 100% by mass of the solid content of the emulsified resin composition. When the content is 1% by mass or less, a crosslinking reaction with a carboxyl group becomes insufficient, and when the metal compound is not used in combination, the carboxyl group particularly lowers the water resistance of the resin film. Further, as described above, there is also a disadvantage that the resin film is made hydrophilic by Na ions or K ions in the alkali compound used in the degreasing step for the post-coating, and the corrosion resistance and the coating property are lowered. On the other hand, if the content is more than 20% by mass, the crosslinking density of the resin film becomes excessively high, and the hardness increases. As a result, it becomes impossible to follow the deformation at the time of press working, and cracks are generated. Is not preferred because it reduces the

The emulsified resin composition used in the present invention includes:
You may contain 5-30 mass% of silica particles in solid content conversion. It is effective in improving corrosion resistance, paintability, scratch resistance, and the like. If the amount is less than 5% by mass, these effects are hardly exhibited, but if it exceeds 30% by mass, the ratio of silica particles becomes excessively high, and the film-forming property is deteriorated. In some cases, leading to a decrease in corrosion resistance. Furthermore, the silica particles will act as a polishing agent, increasing the lubricity of the coating, reducing the coefficient of friction, causing mold wear during processing,
This will shorten the life of the mold. The more preferable upper limit of the silica particles is 20% by mass.

In order to maximize the effect of the silica particles as described above, the average particle size of the silica particles is preferably in the range of 1 to 200 nm. The smaller the particle size of the silica particles, the better the corrosion resistance of the coating. This is considered to further increase the corrosion resistance in order to densify the resin film and improve the adhesion. From this viewpoint, the smaller the particle size of the silica particles is, the better. However, when the particle size is extremely small, the above effect is saturated.
nm is preferred. On the other hand, the particle diameter of the silica particles is 200 n.
If it exceeds m, the surface of the resin film is roughened and a dense resin film cannot be formed, and the silica particles also act as a polishing agent, leading to deterioration in workability, which is not preferable. In particular, when importance is attached to corrosion resistance, it is preferable that the average particle size of the silica particles is in the range of 4 to 100 nm.

Such silica particles are generally known as colloidal silica. In the present invention, for example, “XS” and “SS” of “Snowtex” series (colloidal silica manufactured by Nissan Chemical Industries, Ltd.) are used. , "40",
"N", "UP" and the like can be suitably used.

The wax may be contained in the emulsified resin composition of the present invention in the range of 0.5 to 20% by mass in terms of solid content. Wax is effective in improving the lubricity and scratch resistance of the obtained resin film. Furthermore, deep drawing and punching properties required for press processing and punching processing,
It is preferably used to improve mold wear resistance and blackening resistance of a sliding surface during processing, and to impart excellent workability.

The amount of wax is 0.5% by mass in terms of solid content.
When the amount is smaller, the lubricating property of the obtained resin film becomes insufficient, so that it is impossible to improve the scratch resistance and obtain satisfactory workability. On the other hand, if it exceeds 20% by mass, the lubricating properties of the obtained resin film are sufficient, but the adhesion of the coating film when applied after electrodeposition coating, powder coating or silk printing (paintability) Inferior). One of the causes is
It is considered that the wax is softened and liquefied by the heating in the post-coating process and concentrated at the interface between the resin film and the post-coating film, so that the adhesion of the post-coating film is deteriorated. A more preferred upper limit of the wax is 10% by mass, and a still more preferred upper limit is 5.0% by mass.

The wax is not particularly limited, and natural waxes, synthetic waxes, and mixtures thereof can be used. As the natural wax, for example, carnauba wax, rice wax, candelilla wax, montan wax and derivatives thereof, mineral oil wax, microcrystalline wax, paraffin wax, and the like, and derivatives having a carboxyl group added thereto can also be used. Can be.

Examples of the synthetic wax include polyethylene, polyethylene oxide, polypropylene, an ethylene-propylene copolymer wax, and an oxide wax of a copolymer wax of ethylene and another monomer. This system can be used in various ways including a terpolymer system depending on the change of the copolymerization partner. Further, maleic acid addition wax, fatty acid ester type and the like can be mentioned. In addition, waxes made of fluororesins such as polytetrafluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, and tetrafluoroethylene can also be used.

As the wax, a wax having a softening point of 80 to 140 ° C. is preferably selected from those exemplified above. If the softening point is lower than 80 ° C, the wax particles soften and liquefy as the mold temperature rises during press working and punching, and liquefaction occurs on the sliding surface between the resin-coated steel sheet and the mold. The wax draining phenomenon occurs,
It is not preferable because the processability is reduced and abrasion and seizure with a mold are caused. Further, the blackened matter adheres to the sliding portion, which may significantly deteriorate the appearance of the product. On the other hand, when the softening point exceeds 140 ° C., the lubricity of the wax becomes insufficient, and no improvement in punching properties, mold wear resistance, deep drawability, etc. is recognized, and excellent workability can be obtained. Can not.

As the wax, a spherical polyethylene wax is most preferable. In this case, in order to obtain the maximum effect of the spherical polyethylene wax, the wax particles preferably have a particle diameter of 0.1 to 3 μm. If the particle size of the wax particles is smaller than 0.1 μm, it is difficult to remarkably improve lubricity, punching properties, mold wear resistance, and deep drawability. On the other hand, when the particle diameter of the wax particles exceeds 3 μm, it is difficult to uniformly disperse the wax particles in the finely divided emulsified resin composition, so that the adhesion of the resin film to the metal plate may be reduced. . More preferably, the particle diameter of the spherical polyethylene wax is 0.3 to 1.0 μm.

Examples of the spherical polyethylene wax as described above include “DIJET E-17” (manufactured by Yoyo Kagaku), “KUE-1”, “KUE-5”, and “KUE-
8 (manufactured by Sanyo Kasei Kogyo Co., Ltd.), “Chemipearl” series (manufactured by Mitsui Chemicals, Inc.), “W-100”, “W-200”,
"W-300", "W-400", "W-500",
"W-640", "W-700", etc., and "ELEPON E-
A commercially available product such as "20" (manufactured by Nichika Chemical Co., Ltd.) can be suitably used.

The emulsified resin composition used in the present invention comprises, as essential components, an ethylene-unsaturated carboxylic acid copolymer and an amino alcohol, and, if necessary, a surfactant or an alkali amine, a carboxyl-modified urethane. Resin, metal compound for crosslinking, aziridine compound,
Contains silica particles, wax and the like. When an ethylene-unsaturated carboxylic acid copolymer and a carboxyl-modified urethane resin are used as resin components, the aziridine compound, silica particles, and the like are used so that these resin components are 50% by mass or more of the solid content of the emulsified resin composition. It is desirable to adjust the amount of wax and the like.

The method for preparing the emulsified resin composition is as follows. First, an ethylene-unsaturated carboxylic acid copolymer and an amino alcohol, which are essential components, are charged together with water into a homogenizer or the like, and if necessary, a temperature of 70 to 250 ° C. is added. By stirring with high shear under heating, an emulsified resin composition containing only essential components can be obtained. At this time, an alkali or an amine may be added to promote emulsification. When the carboxyl-modified urethane resin is added, the emulsified resin composition is obtained by adding the carboxyl-modified urethane resin emulsion and the metal compound for crosslinking to the emulsified resin composition at 60 ° C. to room temperature and stirring and mixing. It is preferable to raise the temperature to an appropriate temperature to cause a cross-linking reaction. However, since the resin film is also heated during drying, a cross-linking reaction may be caused at that time.
The silica particles, wax and aziridine compound may be added at any stage with the emulsified resin composition.

The above-mentioned emulsified resin composition contains a diluting solvent, an anti-skinning agent, a leveling agent, a defoaming agent, a penetrant, an emulsifier, a film-forming aid, a coloring pigment,
A thickener, a silane coupling agent, another resin having no functional group or active hydrogen, or the like may be appropriately added.

In order to form a resin film on a metal plate, the above emulsified resin composition is coated on one side of the surface of the metal plate using a known coating method, that is, a roll coater method, a spray method, a curtain flow coater method or the like. Alternatively, it may be applied to both sides and dried by heating. When the aziridine compound is added, the heating and drying temperature is preferably a temperature at which a crosslinking reaction between the aziridine compound and the carboxyl group proceeds. Also,
When a spherical polyethylene wax is used as the lubricant, it is desirable to perform drying at a temperature in the range of 70 to 130 ° C. since maintaining the spherical shape improves the workability in the subsequent processing step.

The amount of adhesion (thickness) of the resin film after drying is preferably 0.2 to 2.5 g / m ² . If the thickness is too thin, it is difficult to uniformly coat a metal plate, and it is not possible to obtain desired balanced film properties such as workability, corrosion resistance, and paintability. However, if the amount of adhesion exceeds 2.5 g / m ² , the grounding property, that is, the conductivity, in the computer housing or the like decreases, which is not preferable. Further, the amount of the resin film peeled off during the press working increases, and the release film adheres and accumulates on the mold, which hinders press molding and is wasteful in terms of manufacturing cost. The lower limit of the more preferable resin film adhesion amount is 0.3 g / m ² , and the upper limit is 1.0 g / m ² .

The resin coated metal plate of the present invention can be obtained by forming a resin film. This resin-coated metal plate can be used as it is after processing according to the application, or it can be used as it is, or can be made by electrodeposition coating, powder coating, silk printing (1.
(30 to 160 ° C., about 20 to 30 minutes).

[0054]

The present invention will be described in more detail with reference to the following examples. However, the following examples do not limit the present invention, and all changes and modifications within the scope of the present invention are included in the present invention. It is.

[Test Method] The test method used in the following examples is as follows. In the case of a five-point evaluation, 5 indicates the best, and 1 indicates the worst.

(1) Corrosion resistance Using a resin-coated steel plate, an edge-sealed flat plate material and an Erichsen-processed material were produced, and a salt spray test was performed on each of them according to JIS Z2371 to determine the time until 1% of white rust was generated. It was measured. The Erichsen extruded height of the Erichsen processed material was 6 mm.

(2) Coatability The obtained resin-coated steel sheet was spray-coated with a melamine-based paint to a thickness of 20 μm after drying by spray coating.
Post-coating was performed by baking at 30 ° C. for 30 minutes. Subsequently, this test material was immersed in boiling water for 1 hour, taken out, and after 1 hour, a 100 mm square of 1 mm square was cut with a cutter knife, and a tape peeling test was carried out on the grid. The coating film adhesion was evaluated on a 5-point scale by the number of remaining meshes.

(3) Dynamic Friction Coefficient In order to evaluate the lubricity of the resin-coated steel sheet, a sliding test apparatus was used to measure the load due to sliding at a pressure of 150 kg to calculate the dynamic friction coefficient.

(4) Workability In order to evaluate the press workability, such as the deep drawability, of the resin-coated steel sheet, a single-shot press test was carried out using an 80-ton crank press, and the molded product was slid after molding. Scratches on the moving surface,
The galling and blackening resistance were visually evaluated, and the overall score was evaluated on a 5-point scale.

(5) Grounding property Tester terminals (+,
−) Was placed lightly, and the resistance of the surface when slid was measured to evaluate the grounding property in five levels.

Experimental Example 1 An electrogalvanized steel sheet (Zn adhesion amount 2
0g / m ² , thickness 0.8mm)
A coating material having an adhesion amount of 20 mg / m ² ) was used. In the present invention, the purpose is to obtain a resin-coated metal plate having excellent corrosion resistance even without performing chromate treatment, and chromate treatment is substantially unnecessary, but for performing a relative evaluation between each experimental example, Chromate treatment was performed.

In order to prepare the emulsified resin composition, 280 parts by mass of water (hereinafter simply referred to as “parts”) are placed in an autoclave.
Against an ethylene-acrylic acid copolymer (acrylic acid 2
0% by mass, melt index (MI) 300) 100
And N-methyldiethanolamine (addition of an average of 2 moles of ethylene oxide) as an amino alcohol in an amount shown in Table 1, and emulsified by high-speed stirring at 180 ° C. and 7 atm for 5 hours. Hereinafter, this emulsion is referred to as EAA emulsion.

Separately, 80 g of polycarbonate diol
To a prepolymer of 3.0 g of neopentyl glycol, neopentyl glycol, 50 g of dimethylolpropionic acid and 70 g of MDI, 8 g of triethylamine and 470 g of water were added, and the mixture was stirred at high speed for 2 hours to extend the chain while emulsifying.
A carboxyl-modified urethane resin emulsion having OH / g and a solid content of about 30% was obtained.

EAA100 in the EAA emulsion
The amount of the urethane resin in the carboxyl-modified urethane resin emulsion is 25% by mass with respect to the mass%.
The two were mixed, and calcium hydroxide was further added so as to be 0.05 equivalent to the total equivalent of the carboxyl group in EAA and the carboxyl group in the carboxyl-modified urethane resin, and mixed well.

Subsequently, trimethylolpropane tri (β
-Aziridinyl propionate) in an amount of 10% by mass in terms of solid content, and silica particles having a particle size of 15 nm (“Snowtex 40”; manufactured by Nissan Chemical Industries, Ltd.) were added in an amount of 1% in terms of solid content.
0% by mass and a spherical polyethylene wax having a softening point of 100 ° C. and an average particle size of 0.6 μm were blended so as to be 5% by mass in the solid content to prepare an emulsified resin composition.

Each composition was applied to one side of the electrogalvanized steel sheet by a roll, and heated and dried at a sheet temperature of 90 ° C. for 1 minute to form a resin coating having a resin film having an adhesion amount of 0.7 g / m ^2. A steel plate was obtained. Table 1 shows the results of each evaluation.

[0067]

[Table 1]

EXPERIMENTAL EXAMPLE 2 The amount of N-methyldiethanolamine was kept constant at 4% by mass based on the ethylene-acrylic acid copolymer, and the amount of the carboxyl-modified urethane resin in the carboxyl-modified urethane resin emulsion was shown in Table 2 with respect to EAA. A resin-coated steel sheet was obtained and evaluated in the same manner as in Experimental Example 1 except that the amount was changed so as to be the amount shown. The results are shown in Table 2.

[0069]

[Table 2]

Experimental Example 3 Except that the amount of N-methyldiethanolamine was kept constant at 4% by mass based on the ethylene-acrylic acid copolymer, and as shown in Table 3, carboxyl-modified urethane resin emulsions having different acid values were used. A resin-coated steel sheet was obtained in the same manner as in Experimental Example 1, and the characteristics were evaluated. The results are shown in Table 3.

[0071]

[Table 3]

Experimental Example 4 The amount of N-methyldiethanolamine was kept constant at 4% by mass based on the ethylene-acrylic acid copolymer, and the amount of trimethylolpropane tri (β-aziridinylpropionate) is shown in Table 4. A resin-coated steel sheet was obtained and evaluated in the same manner as in Experimental Example 1 except that the properties were changed as described above. The results are shown in Table 4.

[0073]

[Table 4]

Experimental Example 5 The procedure of Experimental Example 1 was repeated except that the amount of N-methyldiethanolamine was fixed at 4% by mass based on the ethylene-acrylic acid copolymer and the amount of silica particles was changed as shown in Table 5. Similarly, a resin-coated steel sheet was obtained and evaluated for characteristics. Table 5 shows the results.

[0075]

[Table 5]

Experimental Example 6 The procedure of Experimental Example 1 was repeated except that the amount of N-methyldiethanolamine was 4% by mass based on the ethylene-acrylic acid copolymer and the average particle diameter of the silica particles was changed as shown in Table 6. Similarly, a resin-coated steel sheet was obtained and evaluated for characteristics. The results are shown in Table 6.

[0077]

[Table 6]

Experimental Example 7 The amount of N-methyldiethanolamine was set at 4% by mass based on the ethylene-acrylic acid copolymer, and the amount of spherical polyethylene wax (only one example using carnauba wax) was determined.
The resin-coated steel sheet was obtained in the same manner as in Experimental Example 1 except that the properties were changed as shown in Table 2, and the characteristics were evaluated. The results are shown in Table 7.

[0079]

[Table 7]

Experimental Example 8 Except that the amount of N-methyldiethanolamine was 4% by mass based on the ethylene-acrylic acid copolymer and the particle diameter of the spherical polyethylene wax was changed as shown in Table 8,
A resin-coated steel sheet was obtained in the same manner as in Experimental Example 1, and the characteristics were evaluated. The results are shown in Table 8.

[0081]

[Table 8]

Experimental Example 9 The same as Experimental Example 1 except that the amount of N-methyldiethanolamine was 4% by mass based on the ethylene-acrylic acid copolymer and the amount of resin film attached was changed as shown in Table 9. To obtain a resin-coated steel sheet, and the properties were evaluated. The results are shown in Table 9.

[0083]

[Table 9]

Experimental Example 10 The same procedure as in Experimental Example 1 was carried out except that the amount of N-methyldiethanolamine was 4% by mass based on the ethylene-acrylic acid copolymer, and an electrogalvanized steel sheet not subjected to chromate treatment was used. A resin-coated steel sheet was obtained and its properties were evaluated. The results are shown in Table 10. In addition, instead of the emulsified resin composition of the present invention, “Cemipearl S-650” (registered trademark; manufactured by Mitsui Chemicals, Inc.) was applied to an electrogalvanized steel sheet with a roll using a roll of 0.7
g / m ² to obtain a comparative material. The characteristics were evaluated for each, and the results are shown in Table 10.

[0085]

[Table 10]

[0086]

Since the resin-coated metal sheet of the present invention has a resin film made of a specific emulsified resin composition in the form of fine particles, it not only has excellent corrosion resistance, but also has good paintability, workability and lubrication. The balance of properties such as resistance, scratch resistance, and grounding property was good.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C09D 175/04 C09D 175/04 C23C 22/00 C23C 22/00 Z (72) Inventor Takeshi Watase Kakogawa, Hyogo Prefecture 1 Kanazawa-cho, Kobe Steel Corporation Kakogawa Works (72) Inventor Tadashige Nakamoto 5-9-12 Kita-Shinagawa, Shinagawa-ku, Tokyo F-term (reference) 4F100 AA08A AA08H AA17A AA17H AA20A AA20H AB01B AB03 AB17 AH02A AH02H AH03 AH03H AJ11A AJ11H AK45 AK51A AK71A AL05A AL07A BA02 EH46 EH462 EH71 EH711 EJ05A EJ42 EJ422 EJ69 EJ691 EJ86 EJ862 GB08 GB41 JB02 JM02A YY00A 4J038 BA212 CB022 CB061 CG011 CG061 CJ011 CP04 DF022 DG32 DJ01 GA03 GA06 HA446 JB02 JB09 KA08 NA03 PB06 PB09 PC02 4K026 AA07 AA08 AA09 AA11 AA12 AA22 BA01 BA03 BA12 BB08 CA16 CA38 CA39 D A02 DA09 DA11

Claims (11)

[Claims] 1. An ethylene-unsaturated carboxylic acid copolymer and an amino alcohol represented by the following general formula (1) are used in an amount of 0.1 to 1 based on the ethylene-unsaturated carboxylic acid copolymer.
A resin-coated metal plate comprising a resin film formed from an emulsified resin composition containing 0% by mass. Embedded image (However, 1 to 3 of X, Y and Z are C2 to C4
Alkylene oxide of 1 to 10 mol linked, and
The terminal is a hydroxyl group via the alkylene oxide residue, and the remaining 0 to 2 are lower alkyl groups. ) 2. The resin-coated metal sheet according to claim 1, wherein the ethylene-unsaturated carboxylic acid copolymer is obtained by copolymerizing 1 to 40% by mass of an unsaturated carboxylic acid. 3. The emulsified resin composition further comprises a carboxyl-modified urethane resin and at least one metal compound for crosslinking selected from the group consisting of metal carbonates, metal hydroxides and metal oxides. The resin-coated metal plate according to claim 1. 4. The resin-coated metal plate according to claim 3, wherein the emulsified resin composition contains the carboxyl-modified urethane resin in an amount of 5 to 80% by mass based on the ethylene-unsaturated carboxylic acid copolymer. . 5. The resin-coated metal sheet according to claim 3, wherein the carboxyl-modified urethane resin has an acid value of 3 to 155. 6. The resin-coated metal sheet according to claim 3, wherein the metal compound for crosslinking is a compound of a divalent or higher valent metal element. 7. The resin-coated metal plate according to claim 1, wherein the aziridine compound is contained in an amount of 1 to 20% by mass in 100% by mass of the solid content of the emulsified resin composition. 8. Silica particles having an average particle size of 1 to 200 nm are contained in 5 to 30% in 100% by mass of solid content of the emulsified resin composition.
The resin-coated metal plate according to any one of claims 1 to 7, which is contained by mass%. 9. The resin-coated metal sheet according to claim 1, wherein the wax is contained in an amount of 0.5 to 10% by mass based on 100% by mass of the solid content of the emulsified resin composition. 10. The wax having an average particle size of 0.1.
The resin-coated metal sheet according to claim 9, which is a substantially spherical polyethylene wax having a diameter of from 3 to 3 µm. 11. An adhesion amount of the resin film is from 0.2 to 2.5.
resin coated metal sheet according to claims 1 to 10 is g / m ^2.