JP2005349708A - Print-coated metal sheet and its production method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a print-coated metal sheet which is excellent in light fastness and abrasion resistance and has a pattern high in clearness and rich in cubic effect. <P>SOLUTION: A thermosetting coating film 2 set on the surface of an underlayer metal sheet 1 is dyed with a sublimating dye 4, and a dye holding layer 5 is formed on the surface layer of the thermosetting coating film 2. Next, when a clear coating 6 is applied, heated, and baked, the sublimating dye sublimated from the dye holding layer 5 re-permeates a clear coating film 7. Since a dye dyeing layer 8 is formed in the clear coating film 7 from the thermosetting coating film 2 side by the re-permeation of the sublimating dye, even when the surface layer of the clear coating film 7 is rubbed or abraded, the pattern is not degraded. Since the sublimating dye does not attend the surface layer of the clear coating film 7, lightfastness is also improved. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a printed metal sheet and a method for producing the same, to which a highly designable pattern having excellent sharpness and depth is imparted by sublimation transfer.

In building materials such as home appliances, interior materials, and exterior materials, there is a strong demand for products having a high-grade appearance using design steel plates. This type of design steel plate is formed directly on the base coat film provided on the base steel plate such as plated steel plate, stainless steel plate, cold rolled steel plate by gravure printing, offset printing, etc., and the protective coating film of transparent resin on it Is provided. In some cases, a film having a design pattern printed thereon is laminated on the base coat film.
Since it is troublesome to develop a design pattern that meets various user needs when using gravure printing, offset printing, etc. that require a plate roll, a method of applying a design pattern by thermal transfer of a sublimation dye has recently attracted attention. (Patent Documents 1 and 2). In the thermal transfer method, a transfer sheet coated with a sublimation dye in a predetermined pattern is prepared, and is sublimated and transferred like a picture on a painted surface of a painted metal plate provided with a base coat film. Since a transfer sheet can be manufactured by color xerography or the like as many as required for the manufacturing lot, manufacturing costs can be significantly reduced even in small lot production compared to the case of using plate rolls.
JP-A-8-24778 JP 2002-59078 A

In most conventional sublimation transfer methods, a transfer sheet is brought into contact with the top coating film, and the sublimation dye is transferred from the transfer sheet to the top coating film by pressing and heating. Since the design pattern is expressed by the sublimation dye distributed on the surface layer of the coating film, the design pattern is likely to be deteriorated when the coating film is rusted or worn due to contact with a foreign substance or the like. For this reason, the coating film is prevented from being damaged or worn by overlaying a transparent top coat (clear coating film) on the coating film to which a design pattern has been applied by thermal transfer. When a UV absorber or a light stabilizer is included in the clear coating film, the light resistance of the printed metal sheet is improved (Patent Document 3).
Japanese Patent Laid-Open No. 8-108699

On the other hand, Patent Document 4 introduces that a design pattern is expressed by infiltrating a sublimation dye into the top coating film from the base coating film side. In this method, a transfer sheet in which a release layer, a sublimation dye layer, and an adhesive layer are laminated on a base sheet is used, and the sublimation dye layer is attached to an object to be coated via the adhesive layer. Since a transfer sheet having a multi-layer structure is necessary, it takes time to produce the transfer sheet, which is inconvenient. In addition, since the sublimation dye is provided through the adhesive layer, the sublimation dye is not easily provided on the base coating film in a predetermined pattern, and delamination tends to occur between the base coating film / top coating film.
Japanese Patent Laid-Open No. 54-104907

  The present invention pays attention to the behavior of the heated sublimation dye, and once the sublimation dye has penetrated into the thermosetting coating on the coated metal plate, the clear coating is cleared from the thermosetting coating at the time of heating and baking. By re-infiltrating the sublimation dye into the coating film, a printed pattern with excellent sharpness and depth is expressed by a simple method using a normal transfer sheet rather than a multi-layer structure, wear resistance, light resistance Another object of the present invention is to provide a good printed metal sheet.

  The printed metal sheet of the present invention has a thermosetting coating film dyed with a sublimation dye, and a clear coating film formed from a clear paint dissolved or dispersed in an organic solvent, sequentially laminated on the surface of the metal plate. The design pattern is expressed by the sublimation dye transferred from the thermosetting coating to the clear coating.

  After providing a thermosetting coating on the metal plate surface, dye the thermosetting coating with a sublimation dye, and then apply a clear paint dissolved or dispersed in an organic solvent. By transferring the sublimation dye from the thermosetting coating to the clear coating in the process of being formed, a printed metal sheet with a design pattern applied by the sublimation transfer method is produced.

In the present invention, a coated metal plate provided with a thermosetting coating film is used for a substrate.
As long as there is a thermosetting coating on the surface of the coated metal plate, various types such as a plated steel plate, a stainless steel plate, a cold-rolled steel plate, an aluminum plate, an aluminum alloy plate, a copper plate, and a copper alloy plate can be used as the base metal plate. Although a thermosetting coating film may be provided directly on the base metal plate, it is also possible to laminate the thermosetting coating film via a primer coating film containing a rust preventive pigment if necessary.

  As long as the thermosetting coating film is a dyeable resin that accepts the sublimation dye transferred from the transfer sheet and dyes it well, no particular restriction is imposed on the resin type. Specifically, polyvinyl alcohol, polyvinyl butyral, polyvinyl acetal, polyvinyl acetate, polyvinyl chloride, polyvinyl pyrrolidone, polystyrene-based vinyl resins, polymethyl (meth) acrylate, polybutyl (meth) acrylate, polyacrylamide, polyacrylonitrile, etc. Acrylate resins, polyester resins, polycarbonate resins, polyurethane resins, polyamide resins, urea resins, polycaprolactone resins, polyarylate resins, polysulfone resins, silicone polyester resins, epoxy resins, and copolymers or mixtures of these resins Used as a resin. Of these, polyester resins, polyurethane resins, silicone polyester resins, epoxy resins, and the like that exhibit high dyeing properties for sublimation dyes are preferable. Examples of the crosslinking agent blended in the dyeable resin include melamine-based and isocyanate-based crosslinking agents.

The thermosetting coating film is preferably formed with a film thickness of 3 μm or more. If the film thickness is less than 3 μm, the sublimation dye 4 cannot be sufficiently dyed, and even if the clear coating film 7 is laminated on the thermosetting coating film 2, it becomes difficult to develop a color tone having a sufficient density.
The thermosetting coating film is basically a white coating film for improving the visibility of the design pattern, but in some cases, it is possible to impart a color tone as the background of the design pattern. Or in order to utilize the surface gloss of a base metal plate, you may provide a thermosetting coating film with high transparency.

  A transfer sheet coated with a sublimation dye in a predetermined pattern is used for dyeing a thermosetting coating film. As many transfer sheets as necessary for each production lot are prepared by applying a sublimation dye to the base sheet by electrophotographic method, electrostatic recording method, ink jet method, thermal transfer method or the like.

  As the sublimable dye, a dye that sublimes or evaporates at 70 to 260 ° C. under atmospheric pressure is preferable. Specifically, dyes such as azo, anthraquinone, quinophthalone, styryl, diphenylmethane, triphenylmethane, oxazine, triazine, xanthene, methine, azomethine, acridine, diazine and the like can be mentioned. In addition, 1,4-dimethylaminoanthraquinone, bromide or 1,5-dihydrooxy-4,8-diamino-anthraquinone chloride, 1,4-diamino-2,3-dichloro-anthraquinone, 1-amino-hydro Oxy-anthraquinone, 1-amino-4-hydroxy-2- (β-methoxy-ethoxy) -anthraquinone, 1,4-diamino-anthraquinone-2-carboxylic acid methyl, ethyl, propyl, butyl ester, 1-amino -4-anilide-anthraquinone, 1-amino-2-cyano-4-anilide (or cyclohexylamino) -anthraquinone, 1-hydroxy-2- (p-acetamino-phenylazo) -4-methylbenzene, 3-methyl -4- (Nitrophenylazo) -pyrazolone, 3-hydroxy-quinophthalone, etc. can also be used. Basic dyes modified with malachite green, methyl violet, sodium acetate, sodium etalate, sodium methylate, etc. can also be used.

When the transfer sheet 3 is superimposed on a coated metal plate provided with a thermosetting coating 2 on the base metal plate 1 and pressed and heated, the sublimation dye 4 applied to the transfer sheet 3 is sublimated and thermoset. It moves to the coating film 2 (FIG. 1). Due to the transfer of the sublimable dye 4 from the transfer sheet 3 to the thermosetting coating film 2, a dye holding layer 5 is formed on the surface layer of the thermosetting coating film 2. Preferably, when the sublimation transfer conditions are selected in the range of pressure: 0.05 to 0.5 kg / cm ² and temperature: 140 to 230 ° C., the formation area of the dye-holding layer 5 is limited to the extreme surface layer of the thermosetting coating film 2. Is done. As the pressure to be applied during sublimation transfer, a negative pressure generated by vacuum-sealing a coated metal plate on which the transfer sheet 3 is stacked can be used.

A clear paint 6 dissolved or dispersed in an organic solvent is applied on the thermosetting coating film 2 on which the dye retaining layer 5 is formed.
Organic solvents used for clear paint 6 include ketone solvents such as cyclohexanone, acetone, methyl ethyl ketone, methyl isobutyl ketone, N, N'-dimethylacetamide, N, N'-dimethylformamide, N-dimethyl-2-pyrrolidone, etc. It is preferable to contain at least 2% by mass of a highly polar solvent having a dipole moment of 2.0 D or more.
In an organic solvent prepared by using only a low polarity solvent alone or mixed, the sublimation dye contained in the thermosetting coating film 2 cannot be sufficiently diffused into the clear coating film 7. Low-polar solvents include alcohol solvents such as methanol, ethanol, 2-propanol and n-butanol, ester solvents such as ethyl acetate and butyl acetate, alicyclic hydrocarbon solvents such as hexane, heptane and cyclohexane, benzene , Aromatic hydrocarbon solvents such as toluene and xylene.

  The clear paint 6 can use the same resin as the thermosetting coating film 2 without being restricted by the resin type as long as it is a resin that can receive sublimation dyes and dyes well. Since the clear coating film 7 does not cause any trouble even if it is softened by heat, the addition of a crosslinking agent may be omitted. The clear coating film 7 is preferably formed with a film thickness of 3 μm or more because a necessary amount of sublimation dye is dyed. With a thin film of less than 3 μm, the sublimable dye cannot be sufficiently dyed, and even if the clear coating film 7 is provided on the thermosetting coating film 2, it is difficult to develop a color tone having a sufficient density. An excessively thin film thickness is not preferable from the viewpoint of light resistance and wear resistance.

When the clear coating 6 applied to the thermosetting coating 2 is heated and baked, the sublimation dye 4 dissolves in the process of forming the clear coating 7 from the clear coating 6, and the clear coating 6 from the thermosetting coating 2. 7 As a result, a dye dyeing layer 8 in which the sublimable dye 4 re-penetrates from the dye holding layer 5 to the clear coating film 7 is formed.
The firing temperature of the clear paint 6 is preferably set to 130 ° C. or lower (more preferably 100 ° C. or lower). When baked at a temperature exceeding 130 ° C. for 10 minutes or more, the sublimable dye 4 penetrating into the thermosetting coating film 2 diffuses in the thermosetting coating film 2, and bleeding tends to occur in the image.
It is preferable to form the dye dyeing layer 8 so that the thickness along the direction of the clear coating film 7 having high transparency from the interface of the thermosetting coating film 2 / clear coating film 7 is 3 to 40 μm. If the thickness is less than 3 μm, the amount of the sublimable dye 4 becomes insufficient, and it is difficult to develop a color tone having a sufficient density. Conversely, if the thickness exceeds 40 μm, there is a high possibility that the outline of the image is blurred due to bleeding.

  The dye dyeing layer 8 grows from the interface of the thermosetting coating film 2 / clear coating film 7 into the clear coating film 7 having high transparency, and does not need to be dyed to the surface layer of the clear coating film 7. Since the target design pattern appears in the dye dyeing layer 8 inside the clear coating 7, the printed pattern does not deteriorate even if the surface layer of the clear coating 7 is rusted or worn. The dye dyeing layer 8 grows in the thickness direction of the clear coating film 7, and gives a three-dimensional feeling and depth to the printed pattern. In addition, since there is no dye-dyed layer 8 on the surface of the clear coating film 7, a design pattern with high definition is maintained without fading even when exposed to ultraviolet irradiation for a long time.

[Invention Examples 1 to 9]
Plate thickness: A galvanized steel plate of 0.5 mm was used as a coating original plate. After pre-coating the galvanized steel sheet, apply a white polyester paint (AT-1001 primer: manufactured by Kansai Paint Co., Ltd.) and dry the film temperature: 220 ° C x 1 min. A coated steel sheet provided with a coating film was produced.
By using a sublimation dye ink of cyan by using an image printing system of an ink jet printer system, character information of 10 points was printed in white on a cyan solid background. The obtained transfer sheet was superposed on the thermosetting coating film of the coated steel plate, and thermocompression bonded at a temperature of 155 ° C. and a pressure of 0.4 kg / cm ² for 5 minutes. After completion of crimping, the transfer sheet was peeled from the coated steel sheet.

  As clear paint, 3.0% by weight of triazine UV absorber (TINUVIN400: Ciba Geigy), 1.5% by weight of hindered amine light stabilizer (TINUVIN123: Ciba Geigy) A two-component urethane-based clear paint to which was added was prepared. A clear paint was applied to the thermosetting coating film after the dye-retaining layer was formed, and a clear coating film having a dry film thickness of 2 to 70 μm was formed by baking at a plate temperature of 80 ° C. for 30 minutes.

[Invention Examples 10 to 18]
A coated steel sheet was produced under the same conditions as in Invention Examples 1 to 9 except that an acrylic clear paint was used, and a design pattern was imparted.
[Comparative Examples 19-24]
Thickness: 0.5mm galvanized steel sheet is pre-coated, then the same white polyester paint as in the present invention is used to provide a dry film thickness: 18μm thermosetting coating, and the same UV absorber, light A polyester-based clear paint blended with a stabilizer was applied, and a clear coating film having a dry film thickness of 4 to 18 μm was provided by baking at a plate temperature of 210 ° C. for 1 minute. A transfer sheet was superimposed on this coated steel sheet, and a design pattern was imparted to the clear coating film by applying pressure and heating under the same conditions as in the present invention.

A test piece was cut out from each manufactured printed metal sheet, and the reflection density of the printed coating film surface was measured, and the specimen was subjected to a light resistance test and a design pattern bleeding test.
[Measurement of reflection density]
Four cyan transfer parts of 5 cm × 5 cm were arbitrarily extracted, the reflection density of each cyan transfer part was measured, and the average reflection density was obtained by averaging the measured values.

(Light resistance test)
The test piece was left in a sunshine carbon arc weather meter (test water was sprayed for 12 minutes during irradiation for 60 minutes) set at a test temperature of 63 ° C., and the color tone E of the test piece was measured after 240 hours. The measured value was compared with the color tone of the unirradiated test piece, and the color difference ΔE was calculated.
[Bleeding test]
Test specimens were visually observed and the test specimens where the outline of the printed characters could not be distinguished were marked with ×, the specimens with slightly blurred outlines but no visibility problems were marked with △, and no outline blur was observed The bleeding of the design pattern was evaluated with ○ as a piece.

As seen in the investigation results in Table 1, the present invention example in which the design pattern was developed by allowing the sublimable dye once permeated into the thermosetting coating to re-penetrate into the clear coating during the heating and baking of the clear coating is In contrast to the comparative example in which the design pattern was given by sublimation transfer from the surface layer side of the clear coating film, the light resistance was remarkably improved without significantly deteriorating the reflection density and bleeding resistance.
The excellent light resistance results from the transition from the thermosetting coating to the clear coating and the appearance of the design pattern with a sublimation dye that does not face the surface of the clear coating. Moreover, since the sublimation dye does not reach the surface of the clear coating, even if the surface of the clear coating is rusted or worn due to contact with foreign matter, etc., a design pattern with high definition and rich three-dimensionality is maintained. It was done.

  As explained above, once the sublimation dye is infiltrated into the thermosetting coating on the coated metal plate, the sublimation dye is sublimated again by the heat generated during the firing of the clear coating when the clear coating is formed. Re-penetrate into clear coating. Therefore, a clear coating film can be dyed from the coated metal plate side, and a printed coated metal plate to which a design pattern excellent in light resistance and wear resistance is imparted can be obtained. This printed metal sheet can maintain high design pattern vividness over a long period of time due to its excellent light resistance and abrasion resistance, and is useful as a high-quality exterior material, interior material, exterior material, and the like.

Schematic diagram showing the process in which a design pattern is given by sublimation dye penetrating into a thermosetting coating and re-penetrating into a clear coating.

Explanation of symbols

1: Base metal plate 2: Thermosetting coating film 3: Transfer sheet 4: Sublimation dye 5: Dye holding layer 6: Clear coating 7: Clear coating 8: Dye dyeing layer of clear coating

Claims (2)

  A thermosetting coating film dyed with a sublimation dye and a clear coating film formed from a clear paint dissolved or dispersed in an organic solvent are sequentially laminated on the surface of the metal plate, and the sublimation dye is thermosetting. Printed metal sheet characterized by transition from a paint film to a clear paint film.   After providing a thermosetting coating on the metal plate surface, dye the thermosetting coating with a sublimation dye, and then apply a clear paint dissolved or dispersed in an organic solvent. A method for producing a printed metal sheet, wherein a sublimable dye is transferred from a thermosetting coating to a clear coating in the process of being formed.

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