JP2007237574A - Transfer printing coated metal sheet excellent in weatherability and abrasion resistance - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the weatherability and abrasion resistance of a transfer printing coated metal sheet by forming an overcoat layer 5 while the bleeding of a printed pattern given by a sublimation transfer method is minimized. <P>SOLUTION: A primer layer 6, a base paint film 2, a clear paint film 3, and the overcoat layer 5 are laminated on an underlying metal sheet 1, and a dyed layer 4 is formed by a subliming dye penetrating into the clear paint film 3. The overcoat layer 5 is formed by a quick-drying two-liquid curing urethane coating, suppressing the bleeding of the subliming dye from the dyed layer 4 during film forming. As the quick-drying two-liquid curing urethane coating, a two-liquid curing coating of an acrylic polyol and polyisocyanate is preferable. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a transfer printing coated metal plate that is used for full color outdoor advertising signs, decorative flooring, outer plates of furniture and cooking utensils, and has a design property by transfer printing and is excellent in weather resistance and wear resistance. .

  When manufacturing printed metal plates by transfer printing using sublimation dyes, print the sublimation dyes on the clear top coat of the coated metal plates by printing methods such as offset, silk, gravure, transfer, etc., and apply the sublimation dyes by heat treatment. The clear coating is infiltrated. For example, a method in which a transfer sheet is brought into contact with a curable resin layer and heated (Patent Document 1), a printing layer is formed on a painted metal plate by transfer printing using a sublimation dye, and then a top coating is laminated. A method of infiltrating a sublimation dye from the inside of a coating film by heat treatment (Patent Document 2), a method of infiltrating a heat sublimation ink into a coating film of a prepaint steel plate provided with a primer coating film and a colored top coating film (Patent Document 3) ), A method of infiltrating a sublimation colorant into an opaque resin layer on a metal plate (Patent Document 4), and the like.

Japanese Patent Laid-Open No. 51-24313 Japanese Patent Laid-Open No. 54-104907 JP-A-7-31931 Japanese Unexamined Patent Publication No. 7-102733

  The sublimable dye is an effective dye for forming a printed pattern with high definition. However, it is a disperse dye or oil-based dye having a small polarity, and is easily denatured by a plasticizer or an organic chemical, and is easily decomposed or discolored by being irradiated with light such as ultraviolet rays. For this reason, it is difficult to maintain vivid colors and patterns in outdoor usage environments that are exposed to sunlight for a long time.

Accordingly, the present inventors have conducted various investigations and studies on coating films that suppress the deterioration, discoloration, and discoloration of sublimation dyes. As a result, it was formed from a paint containing a thermosetting polyester resin having a number average molecular weight of 1,000 to 10,000 as a main component and an isocyanate curing agent blended at a ratio of 10 to 50 parts by mass with respect to 100 parts by mass of the resin solid content. It has been clarified that when a coating film is used for a dye-receiving layer, a transfer-printed metal sheet with improved weather resistance can be obtained (Patent Document 5).
JP 2003-285001 A

  By adjusting the molecular weight, crosslink density, and glass transition temperature of the coating film serving as the dye-receiving layer, the sublimation dyes can be prevented from being altered, discolored, and faded to some extent. However, further improvement is necessary to achieve further long-term durability. For example, if a conventional transfer-printed metal sheet is exposed outdoors for more than 5 years, the color change in the colored area becomes ΔE> 15, and the deterioration of the printed pattern cannot be ignored.

  As a means for improving weather resistance and abrasion resistance, it is expected that a clear film having a high ultraviolet absorption effect is laminated on a dye receiving layer dyed with a sublimation dye. In the laminating method, a clear film is attached to a transfer printing painted metal plate using an adhesive, but the sublimation dye diffuses into the adhesive layer at the interface between the top coating and the clear film and prints in a short time. The pattern blurs and the sharpness decreases. In this regard, a method of improving weather resistance and wear resistance by laminating a clear film is not realistic.

  The present invention eliminates bleeding of the printed pattern due to the solvent by forming an overcoat with a quick-drying two-component urethane paint instead of a clear film laminate, and is used outdoors that are exposed to sunlight irradiation over a long period of time. It is an object of the present invention to provide a transfer-printed metal sheet exhibiting durability that hardly discolors and fades, and exhibits sufficient wear resistance as a floor decoration.

The transfer-printed metal plate of the present invention has a dye-receiving layer on which a dye-dyed layer is formed by penetrating a sublimation dye, and is formed from a quick-drying two-component curable urethane paint. The dye-receiving layer is covered with a coated overcoat layer.
As the quick-drying two-component curable urethane paint, an acrylic polyol or polyisocyanate paint added with one or two or more kinds of cellulose ester selected from nitrocellulose, cellulose acetate propionate, and cellulose acetate butyrate is suitable. It is.

Effects and embodiments of the invention

  A transfer printing coated metal plate according to the present invention has a base coating 2 and a clear coating 3 overlaid on a base metal plate 1 (FIG. 1). After dyeing only base coat 2 and clear coat 3 or clear coat 3 with a sublimation dye to form dye-dyed layer 4, form overcoat layer 5 with a quick-drying two-component curable urethane paint . In order to improve the corrosion resistance, a primer layer 6 containing a rust preventive pigment may be provided between the base metal plate 1 and the base coating film 2.

The material of the base metal plate 1 is not particularly limited, but a plated steel plate, a stainless steel plate, a cold rolled steel plate, an aluminum plate, or the like is used. Prior to the formation of the base coating film 2 or the primer layer 6, appropriate pretreatments such as degreasing, washing, replacement treatment, and chemical conversion treatment are performed.
The base coating film 2 is preferably a white coating film having a thickness of 10 to 20 μm. A film thickness of 10 μm or more is necessary to shield the color tone of the underlying metal plate 1, but in the case of a thick film exceeding 20 μm, pinhole-like film defects due to bumping of the solvent remaining in the film during baking ( (Hereinafter referred to as "Waki") is a concern.

  For clear coating 3, a polyester resin with a number average molecular weight of 1000 to 10000 is used as a base to give an appropriate elongation, and a solid content of resin: 10 to 150 parts by mass of melamine or isocyanate in a ratio to 100 parts by mass. A thermosetting polyester resin paint formulated as is preferred. Thermosetting polyester resin paints are well dyed by sublimation dyes, have no significant softening even when heated to 150-200 ° C. during transfer, have excellent stability, and have good storage stability of printed patterns.

  When the polyester resin has a molecular weight of less than 1000, the processability is deteriorated due to insufficient elongation. Conversely, when it exceeds 10,000, the ratio of the cross-linked portion by melamine or isocyanate is reduced, so that it is easily decomposed by ultraviolet rays or the like. Light resistance is improved by adding 10 parts by mass or more of the curing agent, but excessive mixing exceeding 150 parts by mass makes the coating film easily cracked during processing.

The thermosetting polyester resin is synthesized by polycondensation of a dibasic acid and a polyhydric alcohol.
Dibasic acids are aromatic dicarboxylic acids, aliphatic dicarboxylic acids, or acid anhydrides thereof. Specifically, phthalic anhydride, orthophthalic acid, isophthalic acid, terephthalic acid, maleic acid, maleic anhydride, fumaric acid , Adipic acid or the like is used alone or in admixture of two or more. In order to obtain good light resistance, it is particularly preferable that phthalic anhydride and / or orthophthalic acid which forms a 1,2-benzene-dicarbonyl structure after polycondensation is contained. Adipic acid which does not contain a phenyl group is also used as a suitable dibasic acid.

  Examples of the polyhydric alcohol include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, pentyl glycol, neopentyl glycol, trimethylol ethane, and the like, which can be used alone or in combination of two or more. In order to obtain good light resistance, it is preferable to use a glycol having a long aliphatic chain such as pentyl glycol, and it is more preferable to use neopentyl glycol which forms a 2,2-dimethyltrimethylene structure after polymerization.

  The processability of the coating film can also be improved by adjusting the number average molecular weight of the polyester resin and the type and amount of the melamine curing agent to set the glass transition temperature Tg of the clear coating film 3 to 20 to 60 ° C. When the glass transition temperature Tg is less than 20 ° C., the coating film hardness is low and the coating film tends to be wrinkled. Conversely, when the glass transition temperature exceeds 60 ° C., the coating film becomes excessively hard and the workability is remarkably deteriorated.

  It is preferable to add an ultraviolet absorber to the coating material for the clear coating film 3 in order to prevent discoloration of the sublimable dye and decrease in gloss of the coating film under ultraviolet irradiation. Numerous benzotriazole and triazine compounds are known as ultraviolet absorbers, but the weight loss is 10% by mass or less under the condition of heating to 300 ° C. at a heating rate of 5 ° C./min in the atmosphere. The ultraviolet absorber is suitable. Considering the absorption characteristics, combined use of benzotriazole and triazine can be expected to absorb ultraviolet rays in a wide wavelength range. Further, when a light stabilizer such as a hindered amine is added, the light resistance of the clear coating film 3 is further improved.

  The clear coating film 3 preferably has a thickness of 6 μm or more in order to allow a sufficient amount of sublimable dye to permeate and develop a printed pattern. If the film thickness is too thin, satisfactory color tone cannot be imparted due to insufficient penetration of the sublimable dye. The upper limit of the film thickness is not particularly limited, but is adjusted to a film thickness that does not cause coating film defects such as cracks when baking the top coat.

  When silica, glass, nylon, urea resin, acrylic resin, fluororesin, polyethylene resin, polypropylene resin, or the like is dispersed in the clear coating film 3, the coating film has a matte appearance. When flakes such as carbon black, graphite, metal oxide, and metal sulfide are dispersed to adjust the lightness, a coating film having a calm appearance is obtained.

The clear coating film 3 is preferably a transparent or translucent resin coating film having a film thickness of 4 to 25 μm. In a thin film that does not reach 4 μm, a sufficient color tone cannot be obtained due to insufficient adsorption amount of the sublimable dye. The thicker the film, the better the color developability and the reflection density. However, the film thickness of 25 μm or less is preferable in consideration of surface defects that tend to occur during baking. However, when 2-coat 2-bake or 3-coat 3-bake using the same paint, a thick film exceeding 25 μm may be used.
The clear coating film 3 is preferably formed from a thermosetting polyester paint. The firing conditions are set in the range of 100 to 400 ° C. and 1 to 30 minutes in consideration of the reaction conditions of melamine or isocyanate.

  For the formation of the overcoat layer 5, a quick-drying two-component curable urethane paint is used in order to suppress as much as possible the exudation of the sublimation dye from the dye dyeing layer 4 into the solvent in the paint. Two-component curable urethane paints include paints combining polyisocyanates and acrylic polyols with one or more of nitrocellulose, cellulose acetate propionate and cellulose acetate butyrate, nitrocellulose, and cellulose acetate. There are paints combining acrylic polyol modified with one or two of propionate and cellulose acetate butyrate and polyisocyanate.

  Examples of the hydroxyl group-containing vinyl monomer constituting the acrylic polyol include hydroxy (meth) alkyl esters such as 2-hydroxyethyl (meth) acrylate and hydroxypropyl (meth) acrylate, N-methylol (meth) acrylamide, and N-hydroxyethyl. Examples include (meth) acrylamide and hydroxy (meth) acrylamide such as N, N-dihydroxyethylacrylamide. These functional group vinyl monomers having a hydroxyl group can be used alone or in admixture of two or more.

  Other vinyl monomers constituting the acrylic polyol are those copolymerizable with a hydroxyl group-containing vinyl monomer, such as styrene monomer, methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, 2 -Ethylhexyl (meth) acrylate, alkyl esters such as stearyl (meth) acrylate, (meth) acrylamides such as (meth) acrylamide, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N, N-dimethylacrylamide One or more of vinyl monomers containing glycidyl groups such as glycidyl (meth) acrylate, acrylic acid, methacrylic acid, itaconic acid, fumaric acid, maleic acid and the like can be used.

  A polyisocyanate is a compound having two or more free or blocked isocyanate groups in the molecule. For example, diisocyanate compounds such as tetramethylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, phenylene diisocyanate, tolylene diisocyanate, isocyanate adducts obtained by reacting active hydrogen-containing compounds with diisocyanate compounds, frees of isocyanate compounds And a blocked isocyanate compound obtained by blocking the isocyanate group with a blocking agent.

  Nitrocellulose, cellulose acetate propionate, and cellulose acetate butyrate are collectively referred to as “fibrin esters”. The fibrin ester-modified acrylic polyol is produced by a method in which cellulose radicals are generated by irradiating cellulose with radiation having ionizing power, and an acrylic monomer is graft-polymerized. There is also a method of graft polymerization using a radical generated by a redox reaction.

  By blending the fiber ester, the molecular weight distribution of the coating resin is entirely shifted to the polymer side. In addition, since the crystallinity of the fiber ester is higher than that of acrylic resin, the viscosity of the paint suddenly increases from the initial stage when the solvent starts to disperse, and the formation of the coating film form and the reaching of the target coating film hardness can be achieved in a short time. Achieved.

  Due to the excellent quick-drying property, the time for the sublimable dye to ooze out from the dye-dyed layer 4 into the solvent of the urethane paint is greatly shortened, and the deterioration of the printed pattern formed by the dye-dyed layer 4 can be suppressed. The fiber ester is preferably blended in an amount of 1 to 30 parts by mass with respect to the solid content of the coating film resin: 100 parts by mass. If the fiber ester is less than 1 part by mass, the solvent resistance and quick-drying properties will be poor. Impairs workability.

  The acrylic polyol or the fiber ester-modified acrylic polyol preferably has a glass transition temperature Tg of 40 ° C. or higher. The high glass transition temperature Tg is a sign that the molecular weight of the acrylic polyol is increased, and the softening of the overcoat layer 5 can be suppressed even in a high temperature atmosphere. Incidentally, when an acrylic polyol having a glass transition temperature Tg of less than 40 ° C. is used, the sublimation dye is eluted in the rain water due to the softening of the resin by heat, and there is a concern that the weather resistance is lowered. An acrylic polyol having a glass transition temperature Tg of 50 ° C. or higher is particularly preferred for preventing elution of sublimable dyes.

  The coating composition used for forming the overcoat layer 5 is adjusted so that the equivalent ratio of OH / NCO groups is preferably in the range of 10/1 to 1/1. If the equivalent ratio of OH / NCO groups is greater than 10/1, curing is insufficient and the mechanical strength of the urethane coating itself is reduced. On the other hand, when the equivalence ratio is less than 1/1, unreacted NCO groups rich in reactivity remain in the coating film, and there is a concern that the physical properties of the coating film may deteriorate due to the reaction between moisture and NCO groups. Moreover, in order to improve light resistance, it is preferable to add 0.5-8.0 mass parts ultraviolet absorber and 0.1-3.0 mass parts light stabilizer with respect to 100 mass parts of resin solid content of the overcoat layer 5.

The coating material for the overcoat layer 5 is cured at room temperature, but in winter and in cold regions, it may take days to complete the curing. Therefore, it is preferably baked at 40 to 60 ° C. for 15 to 60 minutes. Moreover, when thickening by overcoating, after baking once at 40-60 degreeC for 10-30 minutes, it is preferable to repaint and baking at 40-60 degreeC for 15-60 minutes.
The overcoat layer 5 is preferably formed with a film thickness of 10 μm or more in order to shield the sublimable dye of the dye dyeing layer 4 from ultraviolet rays. If the film thickness does not reach 10μm, not only the sufficient UV shielding effect is obtained, but also a part of the sublimation dye penetrates the overcoat layer 5 and is likely to be eluted. It is difficult to suppress the color tone change of the pattern to ΔE ≦ 15.

In particular, when the overcoat layer 5 is formed with a film thickness of 50 μm or more, it can be expected to have an ultraviolet shielding effect that maintains ΔE ≦ 15 even when exposed outdoors for a long period of time and an effect of preventing the sublimation dye from being eluted out of the film. However, in the case of a thick film exceeding 200 μm, the number of repetitions of coating / firing is increased (the number of repeated coatings), and productivity is lowered. Further, residual stress is accumulated in the overcoat layer 5 and the interlaminar adhesion of the clear coating film 3 / overcoat layer 5 is also a drawback of the coating film that is too thick.
Even when used as a decorative flooring, the overcoat layer 5 has a thickness of 50 to 200 μm in order to balance the abrasion resistance of the printed pattern with the interlayer adhesion of the clear coating 3 / overcoat layer 5. It is preferable to set within a range.

Manufacture of coated steel plate used for transfer master plate: 0.5mm galvanized steel plate is degreased, surface-adjusted and coated chromate treatment is applied, and then white polyester paint is applied in a coating amount so that the dry coating film becomes 5μm. Plate temperature: White base coating film 2 was formed by baking at 220 ° C. for 1 minute.
Next, the clear paint was applied onto the white base coating film 2 in such an application amount that a clear coating film 3 having a dry film thickness of 18 μm was formed.

As a clear paint, a polyester resin having a number average molecular weight of 3000 was a main component, and melamine was blended at a ratio of 60 parts by mass per 100 parts by mass of resin solid content. Furthermore, 8 parts by weight of 1: 1 mixture of triazine UV absorber (Ciba Geigy: TINUVIN 400) and benzotriazole UV absorber (Ciba Geigy: TINUVIN 384), hindered amine light stabilizer (Ciba Geigy) 1.5 parts by mass of TINUVIN 123) manufactured by the company was added.
After coating, the film was baked at a plate temperature of 230 ° C. for 1 minute to obtain a clear coating film 3 having a dry film thickness of 18 μm.

Production of Transfer Sheet A cyan dye (PTB31 (CI Disperse blue 26): manufactured by Mitsubishi Chemical Corporation) was used as the sublimation dye.
Using an inkjet printer (Mimaki Engineering Co., Ltd.) and an inkjet image printing system (Grades System: manufactured by Marking Magic Co., Ltd.) on an inkjet recording paper (S-COAT2: manufactured by Marking Magic Co., Ltd.) A cyan solid pattern was added. Next, a black dye (PTA33 (blend): manufactured by Mitsubishi Chemical Corporation) was used to output a “center line” character (Heisei Kaku Gothic, point: 8), and prepared a transfer sheet with black characters on a cyan tone background. .

From the hot plate 10 side, the coated steel plate 11, the synthetic resin film 12, the transfer sheet 13, and the heat-resistant cushion 14 (conex felt with a thickness of 1mm: Teijin) And made of sandwiched between a smooth hot plate 10 and a rubber sheet 15 (FIG. 2). As the synthetic resin film 12, a film such as polyethylene or polypropylene having a function of transmitting a sublimable dye without being dyed is used. In some cases, the synthetic resin film 12 may be omitted, and the transfer sheet 13 may be in direct contact with the coated steel plate 11.
After setting the coated steel plate 11, the transfer sheet 13, and the like, the whole was vacuumed to 80 kPa, and the transfer sheet 13 was brought into close contact with the coated steel plate 11 with a negative pressure. In this state, it was heated to 160 ° C. for 5 minutes, and after completion of the crimping, the transfer sheet 13 was peeled from the coated steel plate 11.

Formation of Overcoat Layer Overcoat layer 5 was formed on each coated steel sheet after transfer printing as follows.
[Invention Examples 1 to 10]
Weight average molecular weight: 18000 nitrocellulose is added at a rate of 5-30 parts by mass per 100 parts by mass of resin solids, acrylic polyol (Acridic A-801: manufactured by Dainippon Ink & Chemicals, Inc.) and polyisocyanate curing A coating composition was prepared by mixing an agent (Dilanate 24A-100: manufactured by Asahi Kasei Kogyo Co., Ltd.) at a ratio where the equivalent ratio of OH / NCO group was 2/1. Further, 6 parts by mass of a 1: 1 mixture of a triazine-based ultraviolet absorber (TINUVIN 400: manufactured by Ciba-Geigy) and a benzotriazole-based ultraviolet absorber (TINUVIN 384: manufactured by Ciba-Geigy) was added based on the resin solid content. In this example, a coating composition to which 1.5 parts by mass of a hindered amine light stabilizer (TINUVIN 123: manufactured by Ciba Geigy Co.) was added per 100 parts by mass of the resin solid was used for forming the clear coating film 3.

The coating composition was applied to a coated steel plate with a printed pattern using an air spray with a nozzle diameter of 2 mm and an air pressure of 2.5 kg / cm ² . Dry film thickness: After the coating composition was spray-coated at a coating amount of 10 to 30 μm, the process of drying at 60 ° C. for 30 minutes was repeated a plurality of times to form an overcoat layer 5 having a target film thickness. The fact that it can be applied repeatedly after drying for 30 minutes is also an advantage of the quick-drying two-component curable urethane paint.

[Invention Examples 11 to 20]
A coating composition was prepared in the same manner as in Invention Examples 1 to 10 except that cellulose acetate butyrate having a weight average molecular weight of 17000 was used for the fibrous ester, and applied to the coated steel sheet after transfer printing under the same conditions and baked. It was.
[Invention Examples 21-30]
A coating composition was prepared in the same manner as in Invention Examples 1 to 10 except that acrylic modified cellulose acetate butyrate obtained by graft polymerization of acrylic monomer onto cellulose acetate butyrate was added. It was applied and baked.

(Comparative Example 31)
The coated steel sheet provided with a printing pattern by transfer printing was subjected to a physical property test without providing an overcoat layer.
[Comparative Examples 32-34]
A coating composition was prepared by adding a UV absorber and a light stabilizer to a one-pack acrylic paint (Magicron 1000: manufactured by Kansai Paint Co., Ltd.). The coating composition was applied to a coated steel plate with a printed pattern using an air spray with a nozzle diameter of 2 mm and an air pressure of 2.5 kg / cm ² . Further, after the coating composition was spray-coated at an application amount of 10 to 30 μm, the process of drying at 130 ° C. for 60 minutes was repeated a plurality of times to form the overcoat layer 5 having a target film thickness.

[Comparative Examples 35 to 37]
A coating composition was prepared by adding a UV absorber and a light stabilizer to a one-pack aminoalkyd resin paint (Amirac 3000: manufactured by Kansai Paint Co., Ltd.). The coating composition was applied to a coated steel plate with a printed pattern using an air spray with a nozzle diameter of 2 mm and an air pressure of 2.5 kg / cm ² . Further, after the coating composition was spray-coated at a coating thickness of 10 to 30 μm, the step of drying at 100 ° C. for 30 minutes was repeated a plurality of times to form the overcoat layer 5 having a target thickness.

Performance Evaluation of Transfer Printed Metal Plate A test piece was cut out from each manufactured transfer print coated metal plate and subjected to a weather resistance test, a coating adhesion test, a printed character visibility test, and a color tone deterioration test of a printed pattern.

  In the weather resistance test, using a sunshine carbon arc weather meter set at a temperature of 63 ° C on a black panel, the color of the printed part of the cyan solid pattern was measured after 2000 hours under conditions where fresh water was sprayed for 12 minutes during irradiation for 60 minutes. The color difference ΔE was determined by comparison with an unirradiated test piece. Color difference ΔE: Weather resistance was evaluated with ◎ for less than 10, ◯ for 10 to 15, Δ for 15 to 20, and × for 20 or more. If the weather resistance evaluation is Δ or more, it can be said that it is a coated steel plate that can be used practically.

  The coating adhesion test follows the cross-cut method specified in JIS K5600-5-6. For overcoat layer 5 with a film thickness of 0 to 60 μm, the cut interval is 1 mm and the film thickness is 60 to 120 μm. For the overcoat layer 5 with a cut interval of 2 mm and a film thickness of 120 to 250 μm, insert a cross cut of 3 mm for the overcoat layer 5 and observe the surface state of the cross cut part where the coating film is peeled off. The adhesion of the overcoat layer 5 to the clear coating film 3 was evaluated as a standard. A score of 3 or more can be put to practical use.

<Evaluation 0>
The edges of the crosscuts are completely smooth, and no film peeling occurs on any lattice.
<Evaluation 1>
Although slight film peeling occurs at the crossing point of the crosscut, the peeled area does not exceed 5% at the crosscut part.
<Evaluation 2>
The peeling of the coating film occurs along the edge of the crosscut or at the crossing point, and the peeling of the coating film affected by the crosscut portion is in the range of 5 to 15%.

<Evaluation 3>
The coating is partially or completely peeled along the edges of the crosscut, and partial or full peeling of the coating occurs at various portions of the lattice. The peeling of the coating film affected by the crosscut portion is in the range of 15 to 35%.
<Evaluation 4>
The coating is largely or partially peeled along the edges of the crosscut, and partial or full peeling of the coating occurs even at several lattice points. The peeling of the coating film affected by the crosscut portion is in the range of 35 to 65%.
<Evaluation 5>
When peeling of coating film exceeding rating 4 occurs

For the visibility of printed characters, the color unevenness of the cyan solid part is visually observed, x for specimens where the outline of the printed characters is unclear, △ for specimens with slightly blurred outline but no problem with visibility, and outline Visibility was evaluated with a test piece in which printed characters could be clearly read without blurring.
In the color tone deterioration test of the printed pattern, the cyan solid portion was visually observed, and a test piece in a uniform dyed state without color unevenness was evaluated as “◯”, and a test piece in which color unevenness occurred and dyeing was uneven was evaluated as “x”.

As can be seen from the results of the investigation in Table 2, Examples 1 to 30 of the present invention in which the overcoat layer 5 was formed with a two-component curable urethane paint excellent in quick drying showed excellent weather resistance of ΔE ≦ 15. The film adhesion, the visibility of printed characters, and the color tone uniformity of the printed pattern were all good.
In Test Nos. 4, 14, and 24 in which overcoat layer 5 was formed with a film thickness of 200 μm or more, the interlayer adhesion of clear coating 3 / overcoat layer 5 was reduced, but overcoat increased due to an increase in the number of overcoats. This is probably because residual stress was accumulated in the coat layer 5. On the other hand, in test numbers 1, 5, 8, 11, 15, 18, 21, 25, and 28 with a thin overcoat layer 5 of 10 to 15 μm, the color difference after the light resistance test results due to insufficient UV shielding effect It can be seen that ΔE exceeds 15 and that a film thickness of 50 μm or more is preferable in order to obtain a sufficient ultraviolet ray preventing effect.

  On the other hand, in Comparative Example 31 without the overcoat layer 5, the weather resistance was extremely low. In Comparative Examples 32-34 in which the overcoat layer 5 was formed with a one-component curable acrylic resin paint, although the weather resistance was improved, the time required to cure the overcoat layer 5 was long, so the sublimation dye Due to the bleeding, the visibility of printed characters and the color uniformity of the printed pattern deteriorated. Even in Comparative Examples 32-34 in which the overcoat layer 5 was formed with a one-part curable aminoalkyd resin paint, the visibility of printed characters and the color uniformity of the printed pattern deteriorated due to the exudation of the sublimation dye. It was. Also, the better the adhesion of the overcoat layer 5, the worse the weather resistance, and the better the weather resistance, the more the adhesion of the overcoat layer 5 tended to be inferior.

  As described above, when the overcoat layer 5 is superimposed on the clear coating film 3 provided with the transfer printing pattern, light resistance and wear resistance are improved. Moreover, because the overcoat layer 5 is formed with a quick-drying two-component curable urethane paint, the amount of sublimation dye that oozes into the solvent of the paint by the completion of the curing reaction is greatly reduced, and the transferred printing pattern is also blurred. Is prevented. As a result, a transfer printing pattern with high sharpness peculiar to the sublimation transfer method is maintained even when it is used for outdoor use that is exposed to sunlight irradiation for a long period of time or flooring to which stepping pressure is repeatedly applied.

Model diagram explaining the coating film composition of the transfer printed metal sheet Explanatory drawing of the sublimation transfer method in which the transfer sheet is brought into close contact with the coated steel plate under negative pressure

Explanation of symbols

1: Base metal plate 2: Base coating 3: Clear coating 4: Dye-dyed layer 5: Overcoat layer 6: Primer layer
10: Hot plate 11: Painted steel sheet 12: Synthetic resin film 13: Transfer sheet 14: Heat-resistant cushion 15: Rubber sheet
H: Heat input P: Pressure

Claims (2)

  The dye-receiving layer penetrates the dye-receiving layer on the base metal plate to form a dye-dyed layer, and the dye-receiving layer is covered with an overcoat layer formed from a quick-drying two-component curable urethane paint. Transfer printed metal sheet with excellent weather resistance and wear resistance.   The quick-drying two-component curable urethane coating contains one or two or more kinds of fibrous esters selected from nitrocellulose, cellulose acetate propionate, and cellulose acetate butyrate in addition to acrylic polyol and polyisocyanate. 1. A transfer printed metal sheet according to 1.

Images