JP2000167978A - Decoration steel sheet and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To contribute environmental protection, and enhance hot water resistance, anticorrosion, appearance and strength by providing an electrolytic chromate-treated layer formed by a specific quantity metal chrome layer and hydration chromium oxide layer, and also providing a polyester resin layer and pattern printing layer successively at least on one principal surface of a ground steel sheet. SOLUTION: The decoration steel sheet 10 includes an electrolytic chromate- treated layer 4 consisting of a metal chrome layer 2 hydration chromium oxide layer 3 provided on one main surface of a ground steel sheet 1, a polyester resin layer 5 provided on the other hydration chromium oxide layer 3, and also a pattern printing layer 8 consisting of a pattern layer 6 of a predetermined pattern and protection covering layer 7. Of a two layered chromate-treated layer, an adhesion quantity of the metal chrome being a lower layer is made 30 mg/m2 or more per one surface, and an adhesion quantity of the hydration chromium oxide being an upper layer is made 3-30 mg/m2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a decorative steel sheet excellent in hot water resistance and corrosion resistance suitable for members of electric equipment and the like used around water and exterior wall materials and the like located in the vicinity thereof.

[0002]

2. Description of the Related Art A decorative steel sheet having a pattern printed on its surface has been used for exterior parts such as home electric appliances and heating equipment, interior building materials or equipment, etc. by utilizing its design property and the like.

Hitherto, pattern printing has been performed directly on a steel sheet, and a thermosetting or radiation-curing paint has been applied thereon.
She was doing makeup. However, these coatings are susceptible to scratches on the surface during processing such as cutting and bending, and are liable to cause pinholes, and are inferior in hot water resistance and corrosion resistance. In addition, the paint used contains a large amount of organic solvents, releases many organic solvents into the atmosphere during painting, and is environmentally harmful.
In recent years, there has been a shift to performing film lamination instead of painting.

[0004] As such a film-laminated decorative steel plate, there are a type in which a resin film and a steel plate are bonded by using an adhesive when bonding the same, and a type in which the resin film itself is melted by heat and bonded by heat.

The adhesive pressure bonding type is disclosed in, for example,
No. 7031, Japanese Patent Publication No. 4-54580, Japanese Patent Application Laid-Open No. 7-276896, Japanese Patent Application Laid-Open No. 8-34092, Japanese Patent Application Laid-Open No. 8-58017, and Japanese Patent Application Laid-open No. 8-2387.
This is disclosed in, for example, Japanese Patent Application Laid-Open No. 21-210, in which pattern printing is performed in advance on either a steel plate or a resin film, and both are pasted with an adhesive.

Examples of the adhesive used include a thermoplastic resin, a thermosetting resin, and a radiation-curable resin. However, these adhesives, and adhesives further added pigments for printing are inferior in hot water resistance, and when performing a boiling water immersion test or a moisture resistance test, water penetrates into the adhesive layer and swells, Eventually, the film will peel off from the steel plate. For this reason, the conventional adhesive-bonded type film-laminated decorative steel plate is used for members of products such as electric appliances used around water, such as exterior materials for kitchen appliances such as electric washing machines and electric pots, and in the vicinity thereof. There is a problem in using it for the exterior wall material or the like located there.

[0007] A heat-sealing type film laminate in which a pattern is preliminarily printed on either a steel plate or a resin film without using an adhesive, and both are melted by the heat of the resin film itself instead of the adhesive, and then pressed. Decorative steel sheets are disclosed, for example, in JP-A-61-291128 and JP-A-6-25.
No. 4,489, JP-A-6-262726, JP-A-7-52344, JP-A-7-304132, JP-A-8-34093 and the like.
However, when these steel plates are pre-patterned or have a pattern printed on the side of the steel plate of the resin film, the inks for pattern printing impede the adhesion between the steel plate and the resin film, resulting in heat resistance. Poor aqueous. Further, when the steel sheet and the resin film are heat-welded with the pattern printing surface outside, there is no problem with hot water resistance, but there is a problem that the pattern printing is transferred to a heating roll for lamination during the heat welding.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and a first object of the present invention is to apply a film laminate which is more environmentally friendly than a paint containing a harmful solvent and to use a hot water-resistant laminate. Good corrosion resistance, appearance and strength,
It is an object of the present invention to provide a decorative steel plate suitable for members of electric equipment and the like used around water and exterior wall materials located near them.

A second object of the present invention is to apply an environment-friendly film laminate as compared with a paint containing a harmful solvent, and to have a good hot water resistance, corrosion resistance, good appearance and strength,
It is an object of the present invention to provide a method of manufacturing a decorative steel sheet that can be easily obtained at low cost with a decorative steel sheet suitable for members of electric equipment and the like used around water and exterior wall materials located in the vicinity thereof.

[0010]

Means for Solving the Problems The present invention firstly provides a base steel sheet, a metal chromium layer provided on at least one main surface of the base steel sheet and having a thickness of 30 mg / m ² or more per one side, and the metal chromium layer. An electrolytic chromate treatment layer composed of a hydrated chromium oxide layer of 3 to 30 mg / m ^{2 in} terms of metallic chromium per side provided on the layer, a polyester resin layer laminated on the electrolytic chromate treatment layer, A decorative steel sheet comprising: a pattern printing layer formed on the polyester resin layer.

[0011] Second, the present invention provides an electrolytic chromate treatment on at least one main surface of a base steel sheet to form a metal chromium layer of 30 mg / m ² or more per one side;
A step of forming an electrolytic chromate treatment layer comprising a hydrated chromium oxide layer of 3 to 30 mg / m ^{2 in} terms of metal chromium per side, and forming a polyester resin single layer or two layers on the electrolytic chromate treatment layer by thermal lamination Process,
And a method for producing a decorative steel sheet comprising a step of forming a printed layer by performing oil-based or UV printing on a heat-laminated polyester resin layer.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present inventors have studied in detail the bonding mechanism at the bonding interface between a steel sheet and a resin film in order to improve the hot water resistance of a decorative steel sheet.

As the steel plate, tin-free steel (TFS) having relatively good adhesion to the resin film was used. This TFS is a surface-treated steel sheet obtained by performing chromium plating and chromium oxide plating on a base steel sheet.

As a result, it has been found that hydrogen bonding is a dominant factor in the adhesion between the resin film and the TFS interface.
Hydrogen bond adhesion is not very high as compared to covalent bond adhesion. The adhesion is hindered by the presence of a printing ink or the like at the bonding interface.

Further, the present inventors have proposed that a resin film and TFS
We also investigated the deterioration of adhesion in hot water environment and high temperature steam environment. The main factor was that water molecules that permeated the resin film attacked the resin film / TFS interface. As a result, it was found that the portion having poor adhesion was further accelerated in deterioration.

The decorative steel sheet of the present invention has been obtained in consideration of the above-mentioned results, and comprises a base steel sheet, a predetermined amount of a metal chromium layer formed on at least one main surface of the base steel sheet, and a chromium hydrate layer. It has a structure in which a two-layer electrolytic chromate treatment layer composed of an oxide layer, a resin film thermally laminated on the electrolytic chromate treatment layer, and a print layer are sequentially laminated.

Further, in the method for manufacturing a decorative steel sheet according to the present invention, a predetermined amount of a metal chromium layer and a hydrated chromium oxide layer are formed on at least one main surface of a base steel sheet by performing an electrolytic chromate treatment. , A step of sequentially forming, then, a step of thermally laminating a polyester resin monolayer or two layers on the obtained electrolytic chromate treated layer, and printing by performing oily or UV printing on the thermally laminated polyester resin layer. Forming a layer.

According to the present invention, a steel sheet having an electrolytic chromate treatment layer having good adhesion to a resin film is used,
By directly heat-sealing a single layer or two layers of a polyester resin without intervening a printing ink or the like, it becomes possible to prevent deterioration in adhesion at the interface between the resin film and the electrolytic chromate-treated layer. Excellent adhesion is obtained, and hot water resistance, corrosion resistance and strength are improved. Also,
Since the printing layer is formed after performing the thermal lamination of the polyester resin layer, it does not adhere to a heating roll or the like during the thermal lamination, and a good appearance is obtained.

Hereinafter, the present invention will be described in more detail.

FIG. 1 is a schematic diagram showing the configuration of a decorative steel sheet according to the present invention.

As shown in the figure, the decorative steel sheet 10 comprises a base steel sheet 1 and an electrolytic chromate treatment layer 4 composed of, for example, a metal chromium layer 2 and a hydrated chromium oxide layer 3 formed on one of both main surfaces thereof. A polyester resin layer 5 provided on one of the hydrated chromium oxide layers 3, and a pattern printing layer 8 comprising a pattern layer 6 having a predetermined pattern and a protective coating layer 7 provided on the polyester resin layer 5. It is composed of

The base steel sheet used in the present invention is not particularly limited, and any steel sheet can be used as long as it is a steel sheet usually used for this type of surface-treated steel sheet. Specific examples include ordinary low-carbon cold-rolled steel sheets having a thickness of 0.1 to 0.5 mm, low-carbon Al-killed steel sheets, and the like.

In the two electrolytic chromate treatment layers used in the present invention, the amount of metal chromium serving as a lower layer is 30 mg / m ² or more per side, preferably 30 to 3 mg / m ^2.
00 mg / m ² . If the amount is less than 30 mg / m ² , there is a problem in corrosion resistance.

If it exceeds 300 mg / m ² , the performance is not deteriorated at all, but it is not preferable from an economic viewpoint. In any case, there is no problem as long as the amount is used for a normal electrolytic chromate-treated steel sheet.

The amount of the hydrated chromium oxide as the upper layer is as follows:
3 to 30 mg / m ^{2 in} terms of metallic chromium per side. If the adhesion amount is less than 3 mg / m ² , the chromium metal layer is not uniformly covered by the hydrated chromium oxide, the exposed area of the metal layer becomes large, and the corrosion resistance deteriorates and the adhesion between the steel plate and the resin film deteriorates. It is not preferable because of deterioration of hot water. On the other hand, if it exceeds 30 mg / m ² , the appearance deterioration caused by the hydrated chromium oxide layer being too thick,
It is not preferable because it causes deterioration of corrosion resistance and adhesion, resulting in poor hot water resistance.

In the present invention, a polyester resin layer is formed on such an electrolytic chromate treatment layer.

As the resin film used in the present invention, the interface between the resin film and the electrolytic chromate treatment layer is
A material that improves the adhesion at the interface and suppresses water vapor transmission is preferably selected. It is considered that it is necessary to improve the hydrogen bonding with the electrolytic chromate treatment layer in order to have excellent adhesion. To improve the hydrogen bond, a hydroxyl group,
It is desirable to introduce a polar group such as a carboxyl group. Further, a resin film having a rigid ring such as an aromatic ring is effective for suppressing water vapor transmission.

For printing after resin lamination, UV
Printing and oil-based printing are conceivable, but olefin resins such as polyethylene and polypropylene have small surface free energy and are difficult to print. In addition, in the case of oil-based printing, since heat is applied at the time of printing, it is also desired that the heat does not damage the laminate resin itself, and that the adhesion to the steel sheet does not decrease.

In the present invention, a polyester resin such as a specific PET (polyethylene terephthalate) resin is used as the resin film satisfying the above requirements.

Examples of such polyester resins include polyethylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, and ethylene terephthalate / isophthalate copolymer.

When a polyolefin such as polypropylene or polyethylene is used instead of the polyester resin,
Since the water vapor permeability is high, the hot water resistance is inferior, the surface free energy is low, and the printability is poor, and the scratch resistance is poor, which is not preferable.

The polyester resin in the present invention is generally synthesized by melt polymerization. Its molecular weight is preferably 5
The polyester resin composition is composed of a dicarboxylic acid component and a glycol component, but the polymer may be a copolymer obtained by combining several monomers. Examples of the dicarboxylic acid include terephthalic acid, isophthalic acid, and naphthalenedicarboxylic acid. On the other hand, examples of the glycol component include ethylene glycol, 1,2-propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, 1,4-cyclohexanedimethanol and the like. Can be mentioned.

The polyester resin of the present invention can be used in a state where no pigment or the like is contained. Alternatively, it can be used in a state colored with a pigment such as titanium oxide.

The polyester resin layer has a single-layer or two-layer structure with a thickness of 10 μm or more, and it is desirable that the thermal crystallization temperature of the steel sheet adhesive layer is 150 ° C. or more or does not have a thermal crystallization temperature.

When the thickness is less than 10 μm, the film is inferior in scratch resistance, and is likely to have pinholes and the like in the production of a film, and thus tends to be inferior in corrosion resistance.

The steel sheet adhesive layer must not be peeled off from the steel sheet under any environment after lamination. INDUSTRIAL APPLICABILITY The decorative steel sheet of the present invention is suitably used for members of products such as electric appliances used around water and exterior wall materials located near them. In some cases, the pattern printing after lamination is also exposed to 140 ° C. or higher when oil-based printing or the like is performed.

For this purpose, a polyester resin film /
It is essential to maintain the adhesion at the steel sheet interface.

In general, when a polyester resin is exposed to heat at a temperature equal to or higher than the glass transition temperature for a long time, crystallization is accelerated by the heat, and eventually a spherulite is formed. If the spherulites are formed and the film is exposed to water vapor, the adhesion at the interface between the polyester resin film and the steel sheet is remarkably reduced, and the film is eventually peeled off.

Accordingly, the polyester resin used in the present invention may be a single layer or a double layer, and the heat crystallization temperature of the steel sheet adhesive layer is 150 ° C. or more or does not have the heat crystallization temperature. desirable. The polyester resin of the steel sheet adhesive layer has a thermal crystallization temperature according to the result of differential thermal scanning calorimetry (DSC) measurement, and the thermal crystallization temperature is 15
When the temperature is 0 ° C. or lower, spherulites are easily formed and the hot water resistance is poor.
If it is in an amorphous state having a temperature of 150 ° C. or more or having no thermal crystallization temperature, spherulites will not be generated in the heat history of oil-based printing or the like or in the heat history of products such as electric equipment used around water.

When a two-layer polyester resin layer is used, the upper layer of the two-layer film on the side opposite to the steel sheet may or may not have a thermal crystallization temperature, and if it has a thermal crystallization temperature of 150 ° C. or less. But it doesn't matter.

Further, in the present invention, a pattern printing layer is provided on the polyester resin layer. The pattern printing layer is preferably formed of a pattern layer and a protective coating layer, and the layers are formed of vinyl chloride / vinyl acetate copolymer, modified alkyd, polyamide, polyester, polyacryl, polyurethane, polyvinyl acetal, polyester urethane, chloride rubber, and the like. Is used on a polyester resin film together with a solvent and various additives, using a thermoplastic resin as a binder and containing a dye or pigment of an appropriate color as a coloring material. Examples of the method of forming the pattern printing layer include an oil-based printing method in which a curing reaction of a binder resin is performed by heat for evaporating a solvent, and a UV printing method in which a curing reaction is performed by irradiating ultraviolet rays. However, when an oil-based printing method is used, the curing reaction is generally performed for 150 minutes.
Heat of at least ℃ is required. Therefore, in the oil-based printing, it is necessary to consider that the polyester resin layer in contact with the electrolytic chromate-treated layer is not thermally crystallized by heat during the oil-based printing.

As the picture layer, for example, a pearl pigment layer can be used. As the pearl pigment, natural pearl essence obtained by finely pulverizing fish scales, mica powder, or synthetic pearl pigment such as basic lead carbonate, bismuth trichloride, or titanium oxide-coated mica powder can be used. Further, the picture layer may be a single layer or a multi-layer structure in which a colored layer, a pearl pigment layer, a metal thin film layer and the like are combined.

The decorative steel sheet of the present invention is, for example, an electrolytic chromate comprising a predetermined amount of a metal chromium layer and a hydrated chromium oxide layer by subjecting the surface of the steel sheet directly or after chromium plating to electrolytic chromate treatment. After forming the treatment layer,
If necessary, wash with water, or wash and dry, and then heat-laminate a polyester resin film having a thickness of preferably 10 μm or more on the electrolytic chromate-treated layer to form a polyester resin layer, and further form an oily or UV
It can be manufactured by printing.

As the electrolytic chromate treatment method, a commonly used known method can be employed. Examples of such a treatment method include a one-liquid method in which chromium metal and hydrated chromium oxide are simultaneously precipitated, and a two-liquid method in which hydrated chromium oxide is deposited after forming a chromium metal layer.

In order to make the polyester resin to be heat-laminated into a film, a general method of extruding and melting the resin into a film by a T-die method can be used. In addition, the film can be used as it is, in an unstretched state, or in a state where a stretching treatment such as biaxial stretching has been performed.

The polyester resin film is laminated by heat welding. Generally, a method is used in which a steel sheet is heated to a temperature equal to or higher than the melting point of the polyester resin film and the film is pressed using a roll. The laminating technique can be performed by a publicly known method that has been disclosed in a large number.
For example, as a technique for laminating an organic resin film on a metal plate, Japanese Patent Application Laid-Open No. 57-182428,
JP-A-3676 discloses a method in which the metal plate side is heated to a temperature equal to or higher than the melting point of the film and bonded by heat fusion.

The pattern layer and the protective coating layer as the pattern print can be formed on the polyester resin film by various printing methods such as ordinary gravure printing, offset printing and screen printing. The pattern layer can be provided by a conventionally known metal vapor deposition method, and a partially vapor-deposited one or a combination of printing and vapor deposition can be used.

As described above, according to the present invention having such a structure, the deterioration of hot water resistance is suppressed, the manufacture of members for products such as electric equipment used around water, and the exterior members located near them are manufactured. A film-laminated decorative steel sheet applicable to a wall material and the like can be provided.

[0049]

The present invention will be described below in detail with reference to examples.

First, the following test materials were prepared.

Test Materials (1) Surface-treated steel sheet T4C of low carbon Al killed continuous cast steel having a thickness of 0.35 mm
Material A was used as an original steel strip, which was subjected to a surface treatment shown in Table 1 below to obtain a 200 x 300 mm cut plate.

(2) Polyester Resin Layer As shown in Tables 2-1 and 2-2, polyester resin films A to N were prepared, and their thermal crystallization temperatures were measured.

Using a differential scanning calorimeter SSC-5500 manufactured by Seiko Denshi Co., Ltd., the polyester resin film A was heated from 20 ° C. to 280 ° C. at a rate of 10 ° C./min under an air flow of 20 ml / min of nitrogen. did. Immediately after the temperature was raised, the sample was immersed in liquid nitrogen and quenched. The sample was again subjected to 10 ° C./min.
The temperature was raised from 20 ° C. to 80 ° C. at a heating rate of 1 minute, and the peak of the exothermic peak accompanying crystallization (157 ° C.) was taken as the thermal crystallization temperature.

FIG. 2 is a graph showing the measurement results when the polyester resin film A was used.

Polyester resin film A Biaxially oriented polyester film (copolymer of polyethylene glycol and terephthalic acid / isophthalic acid) single layer, containing titanium oxide, white Film thickness: 25 μm From this graph, it can be seen that the thermal crystallization temperature of the film is 176 ° C,
The crystal melting temperature was found to be 229 ° C.

Similarly, the polyester resin film B
For each of 〜 to N, the thermal crystallization temperature was measured. Table 2-1 and Table 2-2 show the results, the type of resin used, the distinction between a single layer and two layers of a resin film, the presence or absence of a pigment, and the color.

FIG. 3 is a graph showing the measurement result of the thermal crystallization temperature of the polyester resin film G as the measurement result of the film in which the polyester resin does not have the thermal crystallization temperature. As shown in the figure, when there is no thermal crystallization temperature, no peak appears in the graph.

Next, a polyester resin film A was thermally laminated on both sides of a 200 × 300 mm cut plate under the following conditions to form a polyester resin layer.

Thermal lamination conditions Steel sheet temperature immediately before lamination: 235 ° C. Laminating speed: 2 m / sec Cooling after lamination: water cooling (rapid cooling) The polyester resin films B to N were also thermally laminated under the same conditions.

(3) Printing Pattern printing on each polyester resin film is performed by using a modified alkyd resin using a stone pattern as a base layer as a pattern layer.
Offset printing was performed using a printing ink to which an isocyanate resin was applied as a curing agent, baked at 150 ° C. for 10 minutes, and dried. Furthermore, after forming a protective coating layer with the same clear varnish, baking and drying were further performed to obtain a pattern printing layer by oil-based printing.

In the UV printing, for example, acrylic (epoxy / acrylate) UV ink and UV clear varnish are used, and after performing the same offset printing, the reaction is advanced by irradiation with ultraviolet rays, and the picture layer and the protective coating are formed. A patterned printing layer consisting of layers was obtained.

Next, examples and comparative examples using the above-described test materials will be described in detail.

Example 1 As shown in Table 1-1, 126 mg of metallic Cr was deposited on a T4CA material having a size of 200 × 300 mm and a thickness of 0.35 mm.
/ M ² , hydrated chromium oxide adhesion amount in terms of metal chromium 1
After performing an electrolytic chromate treatment to a concentration of 6 mg / m ² , a polyester resin film A is laminated on the surface-treated steel sheet as described above, and thereafter, a pattern print is performed by oil-based printing. I got The obtained sample was subjected to a grid test, a pencil hardness test, a peel strength after hot water treatment, and a corrosion resistance test, and its printability, scratch resistance, hot water resistance, and corrosion resistance were evaluated.

Evaluation of Test Material (1) Printability • Cross-cut test evaluation After pattern printing was performed on the resin film, JIS-K5400 was used.
The evaluation was performed by a grid test in accordance with. After performing the tape peeling test, the peeling state of the pattern print on the film surface was observed with a loupe. At that time, five points were assigned to a favorable state without peeling, and the evaluation was made in five stages so that the degree of peeling increased as the number of points decreased to four, three, two, and one according to the peeling state. In addition, only five points out of the five-grade evaluation were evaluated as having good printability.

5 points: 100/100 no peeling, 4 points: 9
9 / 100-75 / 100 No peeling, 3 points: 74/10
0 to 50/100 No peeling, 2 points: 49/100 to 1 /
No peeling of 100 or more, 1 point: 100/100 peeling (2) Scratch resistance-Pencil hardness test After pattern printing on a resin film, JIS-K5400
The evaluation was carried out by a pencil hardness test according to. Those having a pencil hardness of 2H or more were evaluated as having good scratch resistance.

(3) Hot water resistance ・ Peak strength after hot water treatment After pattern printing was performed on the resin film, the steel plate (200 ×
300 mm) in boiling water for 24 hours.
The sheet was cut to a width of 5 mm, and the peel strength between the resin film and the steel sheet was measured at a pulling speed of 100 mm / min.
(Under an environment of 25 ° C. and a humidity of 50%) Those having a maximum peel strength of 1.0 kgf or more with a width of 15 mm were evaluated as having good hot water resistance.

(4) Corrosion Resistance Corrosion Resistance Test After pattern printing was performed on a resin film, the steel plate (200 ×
300mm) into 50mm x 50mm size,
Using a cutter knife, a cross cut was made to reach the steel plate of the sample. The sample was immersed in a 2% aqueous sodium chloride solution at 23 ° C. for 3 days, washed with water and dried, and the degree of peeling of the film at the cross cut portion was evaluated in five steps.

5 points: peel width within 2 mm, 4 points: peel width 2
mm to 4 mm, 3 points: peeling width 4 mm to 7 mm, 2 points: peeling width of 7 mm or more, 1 point: all film peeling 5 points out of the 5 grades, 4 points good corrosion resistance (O)
And 3 points were evaluated as normal (△), 2 points and 1 point as poor (×).

The evaluation results are shown in Tables 1-2 and 1 below.
-3.

As a result, it was found that the obtained decorative steel sheet was not only excellent in printability and scratch resistance, but also excellent in hot water resistance after hot water treatment and corrosion resistance after corrosion resistance test.

Examples 2 to 7 and Comparative Examples 1 to 3 Except that the amount of deposited metal chromium and the amount of hydrated chromium oxide on the electrolytic chromate treated layer were changed as shown in Table 1-1,
In the same manner as in Example 1, a film-laminated decorative steel plate was obtained. Similar tests and evaluations were performed on the obtained decorative steel sheet. The results are shown in Tables 1-2 and 1-3.

As is clear from Tables 1-2 and 1-3,
The amount of metal chromium in the lower layer is 30 mg / m per side^Two
Above, the adhesion amount of the hydrated chromium oxide in the upper layer is 3 to 30 mg.
/ M ^TwoExamples 2 to 7 are all printability, scratch resistance,
Both hot water resistance and corrosion resistance were excellent.

On the other hand, when the amount of deposited metal chromium in the lower layer is 3
Comparative Example 1 with less than 0 mg / m ² was inferior in corrosion resistance.
The amount of chromium oxide hydrate in the upper layer was 3 mg / m ²
Comparative Example 2, which was less than 1, was inferior in hot water resistance and corrosion resistance. Furthermore, the adhesion amount of the upper layer chromium hydrate oxide is 30 mg.
In Comparative Example 3 exceeding / m ² , the appearance was deteriorated, and the hot water resistance and corrosion resistance were poor.

Examples 8 to 10 and 21 Film-laminated decorative steel sheets were obtained in the same manner as in Example 1 except that the thickness of the polyester resin film used was variously changed as shown in Table 1-1. Similar tests and evaluations were performed on the obtained decorative steel sheet. The results are shown in Tables 1-2 and 1-3.

As is clear from Tables 1-2 and 1-3,
In each case, favorable evaluations were obtained in printability, scratch resistance, hot water resistance, and corrosion resistance. However, in Example 21 having a film thickness of 10 μm or less, although the corrosion resistance was slightly lowered, there was no problem in use.

Example 11 A film-laminated decorative steel sheet was obtained in the same manner as in Example 1 except that a pattern printing layer on a polyester resin film was formed by using a UV printing method instead of an oil printing method.
Similar tests and evaluations were performed on the obtained decorative steel sheet. The results are shown in Tables 1-2 and 1-3.

As is clear from Tables 1-2 and 1-3,
It was found that the decorative steel sheet obtained had no problem even when the pattern printing layer was formed using the UV printing method.

Examples 12 to 20, 22 and 23 Table 1-1 and Table 2 show the constitution of the polyester resin film used, that is, the single-layer, two-layer structure, or the polyester resin composition, and the thermal crystallization temperature of the polyester resin film.
-1 and a decorative steel sheet were obtained in the same manner as in Example 1 except for changing as shown in Table 2-2. In Examples 12 to 20, a polyester resin film having a thermal crystallization temperature of 150 ° C. or higher or a thermal crystallization temperature not having a thermal crystallization temperature was used.

In Examples 22 and 23, a polyester resin film having a thermal crystallization temperature of less than 150 ° C. was used. When these samples are subjected to pattern printing with oil-based printing,
Since spherulites are generated by the heat at that time and the hot water resistance may be reduced, pattern printing is performed by the UV printing described above, and otherwise, a film-laminated decorative steel sheet is obtained in the same manner as in Example 1. . These evaluation results are shown in Tables 1-2 and 1
-3.

As is clear from Tables 1-2 and 1-3,
All were excellent in printability, scratch resistance, hot water resistance, and corrosion resistance.

Comparative Examples 4 and 5 As shown in Table 1-1, a film-laminated decorative steel sheet was obtained in the same manner as in Example 1 except that polyethylene and polypropylene films were used as the resin films M and N. These evaluation results are also shown in Tables 1-2 and 1-3.

As is clear from Tables 1-2 and 1-3,
In each case, printability, scratch resistance and hot water resistance were inferior.

[0083]

[Table 1]

[0084]

[Table 2]

[0085]

[Table 3]

[0086]

[Table 4]

[0087]

[Table 5]

[0088]

As described above, according to the present invention,
Applying an environmentally friendly film laminate compared to paints containing harmful solvents, it is excellent in hot water resistance, corrosion resistance, and strength even when used around water, and its appearance is good, A decorative steel plate suitable as a member of a product such as an electric device to be used and an exterior wall material located in the vicinity of the member can be obtained.

According to the present invention, a method for producing a decorative steel sheet having excellent hot water resistance and corrosion resistance without complicated steps is provided, and its economic value is extremely high.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a configuration of an example of a decorative steel sheet according to the present invention.

FIG. 2 is a graph showing the results of differential thermal scanning calorimetry of one example of a polyester resin film that can be used in the present invention.

FIG. 3 is a graph showing the results of differential scanning calorimetry analysis of another example of a polyester resin film that can be used in the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Base steel sheet 2 ... Metal chromium layer 3 ... Hydrated chromium oxide layer 4 ... Electrolytic chromate treatment layer 5 ... Resin film layer 6 ... Picture layer 7 ... Protective layer 8 ... Pattern printing layer 10 ... Decorative steel sheet

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B41M 1/28 B41M 1/28 C23C 28/00 C23C 28/00 C C25D 11/38 301 C25D 11/38 301A 303 303 (72) Inventor Junichi Kitagawa 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Inside Nihon Kokan Co., Ltd. (72) Inventor Toshitaka Sunahara 4--14-12 Koishikawa, Bunkyo-ku, Tokyo Kyodo Printing Co. 72) Inventor Eiichi Kai 4-14-12 Koishikawa, Bunkyo-ku, Tokyo Kyodo Printing Co., Ltd. F term (reference) 2H113 AA01 AA06 BA05 BB13 BC00 BC02 CA05 DA56 DA57 FA35 FA43 4F100 AA22C AB03A AB13B AK25E AK41D AK41E AL06E BA04 BA05 BA07 BA10A BA10E BA13 CA02E EC032 EH112 EJ38D EJ542 EJ69B EJ69C GB07 GB48 HB00 HB31E JA04D JA11D JA12D JB02 JB06 JJ03 JK06 JK1 2 JK20 YY00B YY00C YY00D 4K044 AA02 AB02 BA02 BA15 BA21 BB04 BC02 BC04 BC09 CA16 CA31

Claims (3)

[Claims] 1. A base steel sheet, a metal chromium layer of 30 mg / m ² or more per one side provided on at least one main surface of the base steel sheet, and a metal chromium conversion per one side provided on the metal chromium layer. An electrolytic chromate treatment layer composed of a hydrated chromium oxide layer of 3 to 30 mg / m ² , a polyester resin layer laminated on the electrolytic chromate treatment layer, and a pattern printing layer formed on the polyester resin layer And a decorative steel plate comprising: 2. The polyester resin has a thickness of 10 μm or more and is composed of a single layer or two layers, and the polyester layer in contact with the electrolytic chromate treatment layer has a thermal crystallization temperature of 150 ° C. or more, The decorative steel sheet according to claim 1, wherein the decorative steel sheet has no thermal crystallization temperature. 3. On at least one main surface of the base steel sheet,
By performing electrolytic chromate treatment, 3
And 0 mg / m ² or more metallic chromium layer, forming an electrolytic chromate treatment layer consisting of 3 to 30 mg / hydrated chromium oxide of m ² layer per side reckoned as metal chromium, polyester electrolytic chromate treatment layer A method for producing a decorative steel sheet, comprising: a step of forming a resin single layer or two layers by thermal lamination; and a step of forming a printed layer by performing oily or UV printing on the thermally laminated polyester resin layer.