JP3233913B2 - Resin painted metal plate - Google Patents

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 press formability and weldability such as spot welding and projection welding, and is used for automobiles, household electric appliances, building materials and the like.

[0002]

2. Description of the Related Art Generally, when a metal plate is pressed,
Press oil is applied to the surface of the metal plate to improve its workability.

[0003] However, in a metal plate coated with press oil, the press oil is scattered during press working, which deteriorates the working environment.
Or cause pollution problems. Further, there is a problem that a degreasing step of the press oil is required after the press working.

Therefore, it has been proposed to perform various surface treatments so that good press workability can be exhibited without using press oil. Among these, a resin emulsion or an aqueous resin solution containing an organic solid lubricant is used as a surface treatment agent, which is applied to the surface of a metal plate and dried to form a resin film ( There is a resin-coated metal plate having a dry weight of 0.5 to 5 g / m ² ). This is applied to a product which is subjected to strong processing and a product to which degreasing is omitted after the processing and further coating is performed.

As a specific example of such a resin-coated metal plate, a metal plate coated with a surface treating agent obtained by adding an epoxy resin to a carboxylated polyolefin resin (Japanese Patent Application Laid-Open No. 63-162886). A metal plate coated with a urethane-modified polyolefin resin according to the inventors' proposal and a fluorine-containing resin particle added as a solid lubricant (JP-A-03-17189); What added wax particles to a metal plate and applied is widely used.

[0006]

However, since the resin film containing an organic solid lubricant is formed, the conductivity is poor and the resistance value of the resin surface becomes large during welding. When performing welding, projection welding, or the like, surface sparks and explosion sounds are generated, and problems such as deterioration of electrode life and inability to perform welding occur.

[0007] On the other hand, as a method for improving the weldability of a resin layer, there is a method in which a conductive metal filler is added to a film. This is described in, for example, JP-A-1-127182, JP-A-2-251448, and JP-A-2-251.
As described in JP-A-432-432 and JP-A-2-274537, powder metals such as nickel, stainless steel, iron, copper, zinc, and aluminum having a thickness of 50 to 100 μm are added to a resin film. It is widely used for damping steel sheets. However, in the case of a resin-coated metal plate, the resin film is as thin as 0.5 to 5 g / m ² (the film thickness is about 0.5 to 5 μm) as described above.
It is very difficult to uniformly disperse a μm powder metal, and it is also difficult in terms of cost and safety.

On the other hand, as a method of improving the weldability, a method of reducing the amount of the resin film adhered, that is, a method of thinning the film can be considered. However, in order to realize good press formability, 0.5 to 5 g / g is required. An amount of m ² is required, and it cannot be made thinner than this. If the thickness is kept as it is, there are problems such as generation of surface sparks and explosion noise, and deterioration of electrode life as described above.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems in resin-coated metal sheets, and has excellent lubricity, can perform strong press forming, and can perform spot welding or projection welding after working. Excellent weldability, etc.
It is another object of the present invention to provide a resin-coated metal sheet having excellent coating properties and corrosion resistance.

[0010]

The resin-coated metal plate according to the present invention is a resin-coated metal plate obtained by applying a resin to the surface of a metal plate, wherein the resin is Sb-doped tin dioxide ultrafine particles in a dry weight of 0.1%. A resin mixture containing 5 to 10% by weight, the resin mixture being mainly composed of a urethane resin having active hydrogen in the molecule, and containing 1.0 to 20% by weight of a cold-crosslinkable epoxy resin. Is the gist.

The Sb-doped tin dioxide ultrafine particles have a doping ratio of antimony to tin dioxide as follows:
It is preferable that (Sb / Sn) ≧ 0.2, and it is particularly preferable that the average particle diameter of the Sb-doped tin dioxide ultrafine particles is 0.5 μm or less. Furthermore, the specific surface area of the Sb-doped ultrafine tin dioxide particles is desirably 50 to 120 m ² / g.

In addition, it is preferable that the resin mixture contains 0.5 to 20% by weight of spherical polyethylene wax particles. Furthermore, it is also preferable that the average particle diameter of the spherical polyethylene wax particles in the resin mixture is 0.1 to 3 μm, and the softening point of the spherical polyethylene wax particles in the resin mixture is in the range of 100 to 140 ° C.

Further, the above resin mixture contains 1 as SiO _2.
Preferably, it contains about 30% by weight of colloidal silica.

It is preferable that the resin mixture is applied to the surface of the metal plate at a resin adhesion amount of 0.5 to 5 g / m ² .

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Considering the causes of surface sparks and explosions when spot welding conventional resin-coated metal plates, such a resin film has no current-carrying point, and therefore is located just below the welding electrode. Discharge occurs, and as a result, the metal plate is heated to a high temperature, which is locally melted, and the metal in the nugget gushes out around the electrode, and it is considered that the metal spreads out, that is, surface sparks and explosion sound are generated. Can be

On the other hand, in the case of the resin-coated metal plate of the present invention, the Sb-doped tin dioxide ultrafine particles uniformly dispersed in the resin film form a local current between the resin film and the electrode tip surface during welding. Acts to suppress the concentration of This effect is doubled by compressing the resin film by the pressure of the electrode and making the Sb-doped tin dioxide ultrafine particles more dense.

The resin-coated metal plate obtained by applying the resin mixture containing the ultrafine particles of Sb-doped tin dioxide to a metal plate and drying it as described above, while maintaining the lubricity and the press formability of heavy working. In addition, excellent weldability, particularly spark and explosion sound on the surface of the resin-coated metal plate in spot welding and projection welding can be drastically reduced, and stable bonding strength can be exhibited.

When the content of the ultrafine Sb-doped tin dioxide particles in the resin film is less than 0.5% by weight, the densification of the ultrafine Sb-doped tin dioxide particles in the film becomes insufficient. The effect of suppressing the current concentration described above cannot be obtained. On the other hand, when the content of Sb-doped tin dioxide ultrafine particles is 1
When the content exceeds 0% by weight, the Sb-doped tin dioxide ultrafine particles in the film become excessively confidential at the time of pressurization, resulting in a decrease in current density (heat generation density) between metal plates and insufficient formation of nuggets. Welding becomes poor. On the other hand, if it exceeds 10% by weight, the cost becomes worse. Therefore, S
b-doped tin dioxide ultrafine particles in a dry weight of 0.5 to
It is preferred to contain 10% by weight. More preferably, 1 to 5
% By weight.

Next, a method for producing Sb-doped tin dioxide will be described.

In recent years, Sb-doped tin dioxide has been used in special fields such as the field of semiconductors, and a general manufacturing method is to dissolve tin chloride and antimony chloride in an aqueous hydrochloric acid solution as shown in FIG. This is a method in which an aqueous solution is added for precipitation, and the precipitate is dried to obtain a powder. However, the Sb-doped tin dioxide produced in this way has coarse particles (30 μm or more) and a specific surface area of 5 μm.
Since it is as small as 0 m ² / g, it is difficult to uniformly disperse it in the resin film.

Therefore, in the present invention, the production is performed by the sol-gel method. That is, starting from a solution of antimony and tin hydroxide, Ti, Si, Mg,
By mixing inorganic substances such as Ca, coprecipitated ultrafine particles of antimony and tin hydroxide are precipitated,
By baking at the above high temperature, Sb-doped tin dioxide ultrafine particles (particle diameter 0.5 μm or less, specific surface area 50 to
120 m ² / g). Then, the Sb-doped ultrafine tin dioxide particles are uniformly dispersed in the resin mixture.

Next, the amount of resin adhering to the metal plate surface (the amount of application) will be described.

When the amount of the resin film adhered to the metal plate is 0.5 g /
If it is less than m ² , the required lubricating effect cannot be obtained in heavy working, and good corrosion resistance and applicability cannot be obtained after working. On the other hand, if the amount of adhesion exceeds 5 g / m ² , the amount of peeling of the composite resin film increases in the press working of the steel sheet, and for example, during the press forming, the peeling film accumulates in the mold and hinders the press forming. Occurs. Furthermore, even when welding, the appropriate fineness of the Sb-doped tin dioxide ultrafine particles at the time of electrode pressurization cannot be obtained, so that surface sparks, explosion sound, and the like are generated, thereby deteriorating the weldability. Therefore, the amount of the resin adhered to the metal plate is preferably 0.5 to 5 g / m ² . More preferably, it is 0.7 to 1.0 g / m ² .

Thus, the above resin mixture is applied to a metal plate.
The dried resin-coated metal sheet has excellent weldability and lubricity (press formability), corrosion resistance, and paintability.

Next, the ratio of the antimony doped in tin dioxide in the ultrafine Sb-doped tin dioxide particles contained in the resin film will be described.

When the ratio of antimony doped in tin dioxide is less than Sb / Sn = 0.2, good weldability cannot be obtained.
It needs to be 0.2 or more.

Next, the particle diameter of the Sb-doped ultrafine tin dioxide particles will be described.

When the particle size of the Sb-doped tin dioxide ultrafine particles is larger than 0.5 μm,
It becomes difficult to uniformly disperse the b-doped tin dioxide particles, so that a uniform current-carrying point cannot be exhibited during welding, and the effect of improving weldability cannot be obtained. Further, it is difficult to fix the film in the formed film. Further, since the film forming property of the resin film is deteriorated, the film peels off at the time of press molding, and good press moldability cannot be obtained. Therefore, in order to obtain a resin-coated metal plate having good weldability and press-formability, the Sb-doped tin dioxide ultrafine particles should have a particle size of 0.1.
It is good to set it to 5 μm or less.

Next, the specific surface area of the Sb-doped tin dioxide ultrafine particles in the present invention will be described.

Sb-doped silicon dioxide used in the present invention
The specific surface area of the ultrafine particles is 50 to 120 m.^Two/ G is preferred
No. Specific surface area is 50m^Two/ G
When producing doped tin dioxide ultrafine particles,
It is difficult to uniformly disperse the
Poor stability. Therefore, Sb-doped tin dioxide ultrafine particles
The particles aggregate and precipitate, making redispersion difficult. Meanwhile specific surface
120m^Two/ G to produce ultra fine particles
Are problematic in terms of both technology and cost. Therefore,
A ratio table to provide excellent weldability and press formability
Area 50-12m ^Two/ G range is appropriate.

As described above, the resin-coated metal sheet according to the present invention essentially contains 0.5 to 10% by weight of Sb-doped ultrafine tin dioxide particles. 1.0 to 20% by weight of a room temperature cross-linkable epoxy resin in a urethane resin having active hydrogen in the molecule
It is mainly composed of contained resin.

Next, the main resin component of the resin mixture in the present invention will be described.

As a main resin component, a urethane resin having active hydrogen such as a carboxyl group in a molecule is used. Such a urethane resin is prepared as an aqueous solution or the like, and as the medium, water or water containing a small amount of a water-soluble organic solvent such as alcohol is used.

The method for producing such an aqueous dispersion of a urethane resin having active hydrogen in the molecule is not particularly limited, but can be produced by, for example, the following various methods. .

The urethane prepolymer having a terminal isocyanate group is reacted with an aqueous solution of an amino group or a hydroxyl group and a compound having a sulfonic acid group or a carboxyl group, for example, an alkali or ammonium salt of diaminocarboxylic acid, and the emulsification is performed simultaneously with the chain extension. Do.

A polyol compound, a compound having a quaternary ammonium group and a hydroxy group in a molecule, a compound having an epoxy group and a hydroxy group in a molecule, and the like are reacted with a polyisocyanate, and mixed with water.

The polyol compound is reacted with a polyisocyanate, a polyhydric alcohol and a chain extender in an inert organic solvent (tetrahydrofuran, acetone, methyl ethyl ketone, ethyl acetic acid ethyl, toluene, etc.) to obtain urethane. After adding this to water containing an appropriate amount of an emulsifier, the inert organic solvent is distilled off.

Examples of the above polyol compound include polyether polyol, polyester polyol, polyacetal, polyesteramide, polythioether and the like. The polyether polyol is obtained as a polymerization product or a copolymerization product such as tetrahydrofuran, propylene oxide, and ethylene oxide. The polyester polyol is obtained by a dehydration condensation reaction of a polyhydric alcohol (ethylene glycol, propylene glycol, butanediol, hexanediol, etc.) with a polycarboxylic acid (maleic acid, succinic acid, adipic acid, phthalic acid, etc.), or a cyclic ester. By a ring-opening polymerization reaction of

As the polyisocyanate, aromatic polyisocyanates (1,5-naphthalenediisocyanate, 4,
4-diphenylmethane diisocyanate, phenylene diisocyanate, toluene diisocyanate, etc.) and aliphatic diisocyanates (hexamethylene diisocyanate,
Dicyclohexylmethane diisocyanate, xylylene diisocyanate, etc.).

Typical examples of the chain extender include low molecular weight polyamines such as ethylenediamine, propylenediamine, diethylenetriamine, hexamethylenediamine, and xylylenediamine.

A urethane prepolymer having a terminal isocyanate group is reacted with a polyalkylene polyamine such as diethylene triamine to obtain a polyurethane urea polyamine. An aqueous solution of an acid is added thereto, or an epihalohydrin is added thereto, and then an aqueous solution of an acid is added.

After reacting the above-mentioned polyurethaneurea polyamine or its alkyl isocyanate adduct or epihalohydrin adduct with a dicarboxylic acid cyclic anhydride,
An aqueous solution of a basic substance is mixed.

The polyurethaneurea polyamine or its epihalohydrin adduct is reacted with sultones, lactones or sodium monohalogenated carboxylate, or is reacted with (meth) acrylate or acrylonitrile and then hydrolyzed. And then mixed with water.

A urethane prepolymer having a terminal hydroxyl group or an isocyanate group obtained from a polyol compound and a polyisocyanate is reacted with a diamine, and the obtained terminal amino group compound is emulsified in water using an emulsifier. A polymer is added by adding a polyisocyanate.

Next, the urethane resin in the present invention will be described.

As the urethane resin having active hydrogen in the molecule, in particular, the Shore D hardness of the film (JIS K 72
15), and those having a pencil hardness of H or more are preferably used.

Next, the function of the resin in the present invention will be described.

As a preferred embodiment of the resin-coated metal sheet of the present invention, as described above, a room temperature cross-linkable epoxy resin is used as a cross-linking agent together with a urethane resin having active hydrogen in the molecule as a resin component. ing.

For example, when the urethane resin has a carboxyl group as active hydrogen in the molecule, the carboxyl group reacts with the epoxy group of the cold crosslinking epoxy resin to form an ester group to form a crosslink. I do.
By forming the crosslinks in this way, the film can be made dense and tough, and press formability and corrosion resistance are improved. Also, when the epoxy resin reacts with the carboxyl group of the urethane resin, a hydroxyl group is generated, and it is considered that active hydrogen in the hydroxyl group contributes to the adhesion, and therefore, when a paint is further applied on the resin film, Paintability (hereinafter, simply referred to as paintability) is improved.

As the crosslinking agent for the urethane resin having a carboxyl group in the molecule, other than the above epoxy resin,
There are melamine-based resins, isocyanate-based resins, aziridine-based resins and the like, and these may be used. However, when these are used as a cross-linking agent, the coatability of the resulting resin-coated metal plate is poor.

As described above, by using a cold-crosslinkable epoxy resin together with a urethane resin having active hydrogen in the molecule, the desired film strength can be exhibited, and the temperature rise of the mold in the press forming of strong working can be reduced. In addition, it is possible to obtain a resin-coated metal plate that suppresses abrasion and black change with respect to the extreme pressure of the sliding surface, and further has excellent corrosion resistance, coating properties, and coating properties after processing. The term “black change” refers to a phenomenon in which a metal film slides (contacts) with a metal mold during press molding, whereby the surface of the resin film or the metal plate is peeled off and rubbed, and the color changes to black.

The cold-crosslinkable epoxy resin preferably used in the present invention has a group having a high reactivity with active hydrogen such as a carboxyl group and has good compatibility with the urethane resin, and A crosslinking reaction occurs at a low temperature below the softening point of the spherical polyethylene wax, and those having good liquid stability are preferably used. Examples of such epoxy resins include Denacol EX-313, EX-314,
EX-321, EX-421, EX-512, EX-5
21, EX-147, EX-810, EX-614 (manufactured by Nagase Kasei Kogyo Co., Ltd.), and Ricabond EX-8S
(Manufactured by Chuo Rika Kogyo Co., Ltd.).

Such a cold-crosslinkable epoxy resin is preferably contained in the components of the resin mixture in a range of 1.0 to 20% by weight. When the cold-crosslinkable epoxy resin is less than 1.0% by weight in the resin mixture, crosslinking of the urethane resin becomes insufficient, and the hardness of the obtained resin film is not improved. On the other hand, when the content exceeds 20% by weight, the lubricity of the film is deteriorated, and abrasion is likely to occur in press molding, and further, unreacted epoxy resin remains in the resin film, and the corrosion resistance of the obtained resin-coated metal sheet, In particular, the corrosion resistance after processing deteriorates. Therefore, the above range is preferable,
More preferably, it is in the range of 1 to 10% by weight in the resin mixture.

Next, the spherical polyethylene wax in the present invention will be described.

Spherical polyethylene wax is used as a solid lubricant. When the amount of spherical polyethylene wax particles in the resin mixture is less than 0.5% by weight, lubricity and press formability of the obtained resin film are sufficiently improved. On the other hand, if the content exceeds 20% by weight, there is no particular problem in terms of lubricating performance, but the adhesion between the obtained resin film and the metal plate is deteriorated, and the film is peeled off in press working, and the corrosion resistance after working is reduced. Become inferior. Further, the coatability is also deteriorated in the adhesion between the coating and the paint. Therefore, in the present invention, the amount of the spherical polyethylene wax particles added to the resin mixture is preferably 0.5 to 20% by weight, more preferably 1 to 20% by weight.
10% by weight.

The softening point of the spherical polyethylene wax particles used in the present invention is preferably from 100 to 140 ° C. If the softening point is lower than 100 ° C., the spherical polyethylene wax is softened and liquefied by the rise of the mold temperature during the press working, so that a liquid shortage occurs between the metal plate and the mold, and the workability deteriorates. . On the other hand, spherical polyethylene wax particles having a softening point exceeding 140 ° C. cannot provide good lubrication performance. In addition, the mold temperature in the press molding locally and instantaneously rises to about 200 ° C. in the sliding portion between the mold and the metal plate, but the temperature of the mold and the metal plate in the continuous press molding is
Empirically, it is considered to be about 100 to 120 ° C, and at most 140 ° C.

The state where the wax added as a lubricant (spherical polyethylene wax) exhibits the most effective lubricating effects such as slipperiness and abrasion resistance at the time of contact with the mold is a solid-liquid mixed state. That is, a part of the wax is softened. FIG. 2 is a graph showing the relationship between the softening point of the wax and the workability / lubricity.

The resin film is formed by applying the resin mixture to a metal plate and then drying the mixture. In forming the film, the drying temperature is set to a temperature lower than the softening point of the spherical polyethylene wax particles. The shape of the spherical polyethylene wax particles dispersed in the composite resin film after film formation can be maintained, thereby improving lubricity.

In order to maximize the effect of the spherical polyethylene wax particles, it is preferable that the spherical polyethylene wax particles have a particle diameter in the range of 0.1 to 3 μm. When the particle size exceeds 3 μm, it becomes difficult to uniformly disperse the urethane resin in the aqueous dispersion, and as a result, the adhesiveness of the resulting resin film to the metal plate and the adhesiveness to the paint are deteriorated. I do. On the other hand, when the particle diameter of the spherical polyethylene wax particles is smaller than 0.1 μm, the effect of the addition of the spherical polyethylene wax particles, that is, improvement in film lubrication and corrosion resistance, is not exhibited.

Commercially available spherical polyethylene wax particles include, for example, Dijet E-17 (manufactured by Yoyo Kagaku Co., Ltd.), KUE-1, KUE-5, and KUE-8 (manufactured by Sanyo Chemical Co., Ltd.), and Chemipearl. W-100, W-20
0, W-300, W-400, W-500, WF-64
0, W-700 (manufactured by Mitsui Petrochemical Co., Ltd.), Elepon E
-20 (manufactured by Nikka Kagaku Co., Ltd.).

Next, the colloidal silica used in the present invention will be described.

As the colloidal silica, any one of a spherical or chain shape can be used. By including the colloidal silica in the resin mixture, it is possible to prevent the resin film from being scratched during press molding, and to improve the corrosion resistance.
Paintability is improved.

When the colloidal silica has a chain shape, the length is preferably 40 to 300 mm, and when the colloidal silica is spherical, the diameter is 4 to 300 mm.
It is preferably 40 mm, and the inclusion of the colloidal silica improves the prevention of flaws and the improvement of corrosion resistance and paintability.

If the content of colloidal silica is less than 1% by weight in terms of SiO ₂ , the resulting coating will have insufficient corrosion resistance and coating properties. On the other hand, if it exceeds 30% by weight, the colloidal silica acts as a lubricant, increasing the coefficient of friction of the film and reducing the lubricity, and as a result, deteriorates corrosion resistance and paintability after processing. Therefore,
The content of the colloidal silica is preferably from 1 to 30 wt% as SiO _2. In particular, in order to maximize the effect of colloidal silica, the content is more preferably in the range of 5 to 25% by weight.

Commercial products of such colloidal silica include Snowtex UP, Snowtex 20, Snowtex 40, Snowtex N and Snowtex X.
S, Snowtex S (manufactured by Nissan Chemical Industries, Ltd.).

Next, the metal plate used in the present invention will be described.

The material of the metal plate is not particularly limited. For example, a zinc or zinc alloy plated steel plate,
Aluminum material, aluminum alloy material, stainless steel plate, titanium plate,
Alternatively, those obtained by subjecting these metal plates to a chemical conversion treatment such as a chromate treatment or a phosphate treatment are preferably used.

[0068]

EXAMPLES The present invention will be described below with reference to examples.
The present invention is not limited by these examples.

<Study 1: Study on the Addition Amount of Sb-Doped Tin Dioxide> (Examples 1 to 7, Comparative Examples 1 to 3) Chromate-treated electrogalvanized steel sheet (zinc adhesion amount 20 g) was used as a base metal plate. / M ² , chromium adhesion 20
mg / m ² ).

A Shore D hardness of 51 is used as the base material of the resin film.
Urethane resin (Superflex, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), and cold-crosslinkable epoxy resin
% By weight. As shown in Table 1 below, Sb-doped tin dioxide (average Sb / Sn = 1.0, average particle diameter 0.5 μm, specific surface area about 100 m ² / g) ), And a spherical polyethylene wax (particle diameter 1-2 μm, softening point 10)
0 ° C) 10% by weight of particles and colloidal silica of SiO ₂
Was added and dispersed to obtain a resin mixture.

This resin mixture was squeezed onto the surface of the metal plate.
1g / m dry adhesion amount ^TwoApply so that
And dried at 80 ° C to form a resin film, and resin coating
Metal plates were obtained (Examples 1 to 7, Comparative Examples 1 to 3).

For these, a sliding test, a press test, and a spot welding test were performed as described below.

Sliding test Sliding was performed at a pressure of 150 kg using a sliding test apparatus, and the dynamic friction coefficient was determined from the load. The kinetic friction coefficient was measured simultaneously on both sides, and the results were displayed on one side.

Press Test After press-molding using a single-shot press tester, the sliding surface of the molded product was visually evaluated for die galling and blackening comprehensively to evaluate the mold galling resistance.

-Spot welding test: Dome type made of 1% Cr-Cu (tip diameter 6 mm, 40
mmR) electrode, pressure 2156N (220kg)
f), current 8 kA, conduction cycle 12 cycles (60 Hz)
Then, spot welding at 1000 spots was carried out, and the percentage of good welding points to all welding points was determined and defined as weldability. In addition, the occurrence of surface scattering (surface spark) at all hit points was visually evaluated.

Table 1 shows the results.

[0077]

[Table 1]

As can be seen from Table 1, when the amount of Sb-doped tin dioxide is less than 0.5% by weight, the weldability and surface spark are poor. When the amount exceeds 10% by weight, the dynamic friction coefficient is high, and The evaluation of mold galling, weldability and surface spark was poor. On the other hand, the range of 0.5 to
At 10% by weight, it was good in each of the above tests.

<Study 2: Study on the type of cross-linking agent and its concentration added> (Examples 8 to 12, Reference Examples 1 to 5) In the same manner as in Study 1 above, as a material metal plate, electrozinc treated with chromate Coated steel sheet (Zinc adhesion 20g /
m ² , 20 mg / m ^{2 of} chromium adhering amount).

As in the above study 1, a urethane resin having a Shore D hardness of 51 (Superflex manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) was used as a base material of the resin film, and a room temperature crosslinkable epoxy resin was added thereto in an amount of 0.5. ２５25% by weight. 5% by weight of Sb-doped tin dioxide (average Sb / Sn = 1.0, average particle size 0.5 μm, specific surface area of about 100 m ² / g), and spherical polyethylene wax (in terms of total solid content after film formation) (Particle size 1-2 μm, softening point 100 ° C)
10% by weight of particles and 10% by weight of colloidal silica as SiO ₂ were added and dispersed to obtain a resin mixture.

The resin mixture was applied to the surface of the metal plate by a squeeze roll so as to have a dry adhesion amount of 1 g / m ^2, and dried at 80 ° C. to form a resin film, thereby obtaining a resin-coated metal plate. (Examples 8 to 12, Reference Examples 1 and 2).

As a reference example, 5% by weight of a crosslinking agent of a melamine resin, an isocyanate resin or an aziridine resin was blended with the same urethane resin as the above in place of the cold crosslinking epoxy resin to prepare a resin mixture. And
Similarly to the above, it was applied to the surface of the metal plate and dried to obtain a resin-coated metal plate (Reference Examples 3 to 5).

With respect to these Examples and Reference Examples, a sliding test, a press test, and a spot welding test were performed in the same manner as in Study 1 described above, and the following salt spray test and adhesion test were performed.

Salt spray test A salt spray test was performed according to the method described in JIS Z 2371, and the corrosion resistance was examined. The results are indicated by 1% white rust generation time of SST white rust of the bare plate.

Adhesion Test After coating with an acrylic or melamine alkyd paint, the adhesion of the coating film with the base and Ericksen was examined.

Table 2 shows the results.

[0087]

[Table 2]

As can be seen from Table 2, as the additives, those using 1 to 20% by weight of a cold crosslinking epoxy resin were good.

<Study 3: Examination of Amount of Resin Coating> (Examples 13 to 17, Reference Examples 6 and 7) As in the case of Study 1 described above, a chromate-treated electrogalvanized steel sheet ( Zinc adhesion 20g /
m ² , 20 mg / m ^{2 of} chromium adhering amount).

As in the case of the above study 1, the base material of the resin film was
Urethane resin with Shore D hardness of 51 (Daiichi Kogyo Seiyaku)
Room temperature cross-linking
5% by weight of the epoxy resin was mixed. After film formation
Sb-doped tin dioxide (average Sb / Sn
= 1.0, average particle size 0.5μm, specific surface area about 100m
^Two/ G) and 5% by weight of spherical polyethylene wax
(Particle size 1-2 μm, softening point 100 ° C.) 10 weight of particles
%, Colloidal silica is SiO_Two10% by weight
And dispersed to obtain a resin mixture.

The resin mixture was applied to the surface of the same metal plate as described above using a squeezing roll so as to have a dry adhesion of 0.5 to 5 g / m ^2, and dried at 80 ° C. to form a resin film. Resin-coated steel sheets were obtained (Examples 13 to 17, Reference Examples 6, 7).

The above-mentioned study 2
The same test was performed to check the performance.

Table 3 shows the results.

[0094]

[Table 3]

<Study 4: Study on Particle Diameter and Softening Point of Spherical Polyethylene Wax> (Examples 18 to 21,
Reference Examples 8 to 11) In the same manner as in Study 1 above, as a material metal plate, an electrogalvanized steel sheet subjected to a chromate treatment (a zinc adhesion amount of 20 g /
m ² , 20 mg / m ^{2 of} chromium adhering amount).

As in the case of the above-mentioned study 1, a urethane resin having a Shore D hardness of 51 (Superflex manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) was used as a base material of the resin film, and a room temperature crosslinkable epoxy resin was added at 5% by weight. Was blended. The amount of Sb-doped tin dioxide (average Sb
/Sn=1.0, average particle size 0.5 μm, specific surface area about 1
00 m ² / g) and 10% spherical polyethylene wax having various particle sizes and softening points shown in Table 4 below.
10% by weight of colloidal silica as SiO ₂
In addition, the mixture was dispersed to obtain a resin mixture.

This resin mixture was applied to the surface of the metal plate by a squeezing roll so as to have a dry adhesion amount of 1 g / m ^2, and dried at 80 ° C. to form a resin film, thereby obtaining a resin-coated steel sheet ( Examples 18 to 21 and Reference Examples 8 to 11).

The above-mentioned study 2
The same test was performed to check the performance.

Table 4 shows the results.

[0100]

[Table 4]

As can be seen from Table 4, the particle diameter of the spherical polyethylene wax is preferably 0.1 to 3, and the softening point is 100 to 1.
40 ° C is better.

That is, the spherical polyethylene wax changes between a liquid / solid-liquid mixture / solid state across the softening point. As described above, the temperature of the mold and metal plate during continuous press molding is generally 100 to 120 ° C. (at most 140 ° C.). Therefore, in the case of a spherical polyethylene wax having a softening point of less than 100 ° C., the wax softens. As a result, the liquid is not in a solid-liquid mixed state having a good lubricating effect. Therefore, the sliding of the mold causes the liquid to run out between the metal plate and the mold, and the abrasion preventing effect is lost and the workability is deteriorated. On the other hand, in the case of a spherical polyethylene wax having a softening point of more than 140 ° C., the wax solidifies, and the solid-liquid mixed state having a good lubricating effect is also lost, so that the lubricating property is poor and the metal plate does not easily flow into the mold. Become.

<Study 5: Examination of the SiO ₂ concentration of colloidal silica and the concentration of spherical polyethylene wax> (Examples 22 to 26, Reference Examples 12 to 14) As in Study 3, Shore as a base material of the resin film 5% by weight of a normal temperature crosslinkable epoxy resin was mixed with a urethane resin having a D hardness of 51 (Superflex manufactured by Daiichi Kogyo Seiyaku Co., Ltd.). Sb in terms of total solid content after film formation
5% by weight of doped tin dioxide (average Sb / Sn = 1.0, average particle diameter 0.5 μm, specific surface area about 100 m ² / g), and spherical polyethylene wax (particle diameter 1-2 μm)
m, softening point 100 ° C.) 0.5 to 25% by weight of particles and 1 to 35% by weight of colloidal silica as SIO ₂ were added and dispersed to obtain a resin mixture.

In the same manner as in Study 3, this resin mixture was applied by a squeezing roll so as to have a dry adhesion amount of 1 g / m ² .
The resin film was formed by drying at 80 ° C. to obtain a resin-coated steel sheet (Examples 22 to 32, Reference Examples 12 to 17). In Example 30, 10% by weight of chain colloidal silica (average length 200 mm) was added.

Regarding this resin-coated metal plate, the above study 2
The same test was performed to check the performance.

The results are shown in Tables 5 and 6.

[0107]

[Table 5]

[0108]

[Table 6]

<Study 6: Study on the type of metal plate>
(Examples 33 to 39, Comparative Examples 4 to 9) In the same manner as in Study 3 above, a room temperature cross-linkable type was formed on a urethane resin (Shoreflex manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) having a Shore D hardness of 51 as the base material of the resin film. 5% by weight of an epoxy resin was blended. Sb in terms of total solid content after film formation
5% by weight of doped tin dioxide (average Sb / Sn = 1.0, average particle diameter 0.5 μm, specific surface area about 100 m ² / g), and spherical polyethylene wax (particle diameter 1-2 μm)
m, softening point 100 ° C.) 0.5 to 25% by weight of particles and 1 to 35% by weight of colloidal silica as SiO ₂ were added and dispersed to obtain a resin mixture.

This resin mixture was applied to various metal plates shown in Table 7 below by a squeezing roll so as to have a dry adhesion amount of 1 g / m ^2, and dried at 80 ° C. to form a resin film. Steel plates were obtained (Examples 33 to 39).

For comparison, among the above resin mixtures, a resin mixture containing no Sb-doped tin dioxide was prepared, applied to various metal plates in the same manner as described above, and dried to form a resin film. (Comparative Examples 4 to 9).

For these resin-coated metal plates, the same test as in Study 2 above was performed, and the performance was examined.

Table 7 shows the results.

[0114]

[Table 7]

As can be seen from Table 7, the resin-coated metal plate obtained by applying the resin mixture containing Sb-doped tin dioxide according to the present invention showed good results, but did not contain Sb-doped tin dioxide. Those coated with the resin mixture showed poor results.

[0116]

The resin-coated metal plate according to the present invention is obtained by applying and drying a resin mixture containing Sb-doped tin dioxide ultrafine particles on the surface of the metal plate. It is possible to perform strong working press forming without applying, and is excellent in spot welding and projection weldability. Furthermore, this resin-coated metal plate also has excellent paintability and corrosion resistance.

[Brief description of the drawings]

FIG. 1 is a diagram showing a general method for producing Sb-doped tin dioxide.

Fig. 2 Softening point and processability of spherical polyethylene wax
4 is a graph showing a relationship with lubricity.

Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI B32B 15/08 B32B 15/08 T (56) References JP-A-6-196110 (JP, A) JP-A-2-202443 (JP, A) JP-A-5-5069 (JP, A) JP-A-5-311454 (JP, A) JP-A-3-263705 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B05D 7/14 B05D 7/24 302 B05D 7/24 303 B32B 15/08

Claims (9)

(57) [Claims] 1. A resin-coated metal plate obtained by applying a resin to the surface of a metal plate, wherein the resin comprises a resin mixture containing 0.5 to 10% by weight of ultra-fine particles of Sb-doped tin dioxide by dry weight, The resin mixture is mainly composed of a urethane-based resin having active hydrogen in the molecule, and a cold-crosslinkable epoxy-based resin is used in an amount of 1.0 to 1.0.
A resin-coated metal plate containing 20% by weight. 2. The doping ratio of antimony to tin dioxide in the Sb-doped tin dioxide ultrafine particles is (S
2. The resin-coated metal sheet according to claim 1, wherein (b / Sn) ≧ 0.2. 3. The resin-coated metal sheet according to claim 1, wherein the Sb-doped tin dioxide ultrafine particles have an average particle size of 0.5 μm or less. 4. The resin-coated metal sheet according to claim 1, wherein the specific surface area of the Sb-doped tin dioxide ultrafine particles is 50 to 120 m ² / g. 5. The resin-coated metal sheet according to claim 1, wherein said resin mixture contains 0.5 to 20% by weight of spherical polyethylene wax particles. 6. The resin-coated metal sheet according to claim 5, wherein the spherical polyethylene wax particles in the resin mixture have an average particle diameter of 0.1 to 3 μm. 7. The resin-coated metal sheet according to claim 5, wherein the softening point of the spherical polyethylene wax particles in the resin mixture is in a range of 100 to 140 ° C. 8. The resin-coated metal sheet according to claim 1, wherein the resin mixture contains 1 to 30% by weight of colloidal silica as SiO ₂ . 9. The resin-coated metal plate according to claim 1, wherein the resin mixture is applied to the surface of the metal plate in an amount of 0.5 to 5 g / m ² as a resin adhesion amount.