JP2020073634A - Composition for upper layer side adhesion layer and composition for lower layer side adhesion layer - Google Patents

Abstract

To provide a novel and improved ornamental design metal plate capable of suppressing deterioration of a design applied on a design film during preparation of the ornamental design plate and capable of maintaining adhesion force between the design film and the metal plate even under a severe environment such as high temperature and high humidity, and its production method.SOLUTION: In order to solve the above problem, according to an aspect of the present invention, an ornamental design metal plate including a metal plate, a lower layer side adhesion layer laminated on the metal plate, an upper layer side adhesion layer laminated on the lower layer side adhesion layer, and an ornamental design film laminated on the upper layer side adhesion layer, in which the lower layer side adhesion layer contains a lower layer side adhesive, the upper layer side adhesion layer contains an upper layer side adhesive, a softening temperature of the upper layer side adhesive is 80°C or lower, and the softening temperature of the lower layer side adhesive is 90°C or higher, is provided.SELECTED DRAWING: Figure 2

Description

  TECHNICAL FIELD The present invention relates to a design metal plate and a method for producing the same, and more particularly to an upper layer side adhesive layer composition and a lower layer side adhesive layer composition used therein.

  In recent years, it has been used as an interior / exterior of various structures (for example, interior / exterior walls of houses, roofs, partitions, etc.), furniture parts, housings of home appliances, truck mounting, vehicle interior / exterior, ship interior / exterior, and road protection walls. Steel sheets are increasingly used. Of these uses, the design steel sheet is often applied to the interior and exterior of a house, and particularly to the wall of a residential bathroom.

  Here, the design steel sheet is obtained by laminating a design film on a steel sheet. The design film is a film to which various designs (for example, color, pattern, emboss, etc.) are provided. The design steel plate is roughly produced by the following steps. That is, first, by laminating (eg, coating) an adhesive on a steel plate or a design film, an adhesive layer is formed on the steel plate or the design film. Here, the adhesive may be laminated on the steel plate or the design film in a state of being dissolved in the solvent or dispersed in the solvent. Then, the adhesive is softened by heating the adhesive layer. When the adhesive layer contains a solvent, the solvent is evaporated by heating. Then, the steel plate and the design film are pressure-bonded. A design steel plate is manufactured by the above process.

  Patent Documents 1 to 6 disclose design steel sheets in which the adhesive layer is a single layer. Patent Document 1 discloses a polyester adhesive in which a polyisocyanate-based curing agent is blended with a urethane-modified polyester base material in which the molecular weight and the amount of terminal functional groups are defined so that the NCO / OH ratio falls within a predetermined range. .. And in patent document 1, the adhesive layer which consists of a single layer is formed on a steel plate using this adhesive agent. And a design film and a steel plate are pressure-bonded.

  According to the technique disclosed in Patent Document 1, the molecular weight of the main agent is regulated to maintain the wettability to the design film and the strength of the adhesive itself. Further, by defining the terminal functional group, the adhesion between the steel plate and the design film is secured. Then, the cohesive force and pot life are optimized by defining the compounding ratio of the curing agent. The adhesive disclosed in Patent Document 1 softens at a low temperature (for example, 180 ° C. or lower). Therefore, even if the heating temperature of the adhesive layer is low, the adhesive is sufficiently softened, so that the design film can be sufficiently adhered to the steel sheet.

  Further, Patent Document 2 discloses an acrylic adhesive in which an acrylic polymer combined with an epoxy resin is crosslinked with an amine compound. In Patent Document 2, a single-layered adhesive layer is formed on a steel sheet using this adhesive. The adhesive disclosed in Patent Document 2 also softens at low temperatures. Therefore, even if the heating temperature of the adhesive layer is low, the adhesive is sufficiently softened, so that the design film can be sufficiently adhered to the steel sheet.

  Further, Patent Document 3 discloses a polyester-based adhesive using polyisocyanate containing a silane coupling agent as a curing agent. In Patent Document 3, a single-layered adhesive layer is formed on a steel sheet using this adhesive. Patent Documents 4 to 6 also disclose commercially available polyester-based or urethane-based adhesives. Also in Patent Documents 4 to 6, an adhesive layer composed of a single layer is formed using these adhesives. The adhesives disclosed in Patent Documents 3 to 6 soften at a high temperature (for example, 210 to 230 ° C.). Therefore, when the design film is pressure-bonded to the steel sheet using these adhesives, the heating temperature of the adhesive layer needs to be higher than the heating temperatures of Patent Documents 1 and 2.

  Patent Documents 7 and 8 disclose design steel plates having two adhesive layers. In Patent Document 7, the adhesive layer on the lower layer side (that is, the steel sheet side) contains an adhesive containing a polar group-containing modified polyethylene resin as a main component, and the adhesive layer on the upper layer side (that is, the design film side) is polar group-containing modified It includes an adhesive containing polypropylene resin as a main component. The adhesive containing a polar group-containing modified polypropylene resin as a main component is an adhesive that softens at high temperature, and the adhesive containing a polar group-containing modified polyethylene resin as a main component is an adhesive that softens at low temperature.

  In Patent Document 7, a design steel sheet is produced by the following steps. That is, a multi-layer extruder is used to form a plurality of adhesive layers on the design film. Then, the design film on which these adhesive layers are formed is pressure-bonded to the preheated steel plate. Then, by heating the design film and the steel plate, the adhesive on the lower layer side is softened to bring the design film into close contact with the steel plate. A design steel plate is manufactured by the above process. Here, since the adhesive on the lower layer side is composed of an adhesive that softens at low temperature, even if the heating temperature for softening the adhesive on the lower layer side is low, the design film is sufficiently adhered to the steel sheet. be able to.

  In Patent Document 8, the lower adhesive layer contains a urethane adhesive having a glass transition temperature of −65 to −10 ° C., and the upper adhesive layer contains a polyester adhesive having a glass transition temperature of 20 to 90 ° C. .. The urethane adhesive has a low glass transition temperature and therefore softens at a low temperature. Since the above polyester-based adhesive has a high glass transition temperature, it softens at a high temperature. In Patent Document 8, a design steel sheet is manufactured by the following steps. That is, an emulsion containing a urethane-based adhesive is laminated on a steel plate and heated to form a lower adhesive layer on the steel plate. Then, an emulsion containing a polyester-based adhesive is laminated on the lower adhesive layer and heated to form the upper adhesive layer on the lower adhesive layer. Then, a design film is laminated on the upper adhesive layer. Here, since the lower adhesive layer is composed of an adhesive that softens at a low temperature, even if the heating temperature for softening the lower adhesive is low, the design film should be sufficiently adhered to the steel sheet. You can

JP-A-5-140340 JP-A-56-90874 Japanese Patent Publication No. 6-78517 JP, 2010-6020, A JP, 2005-219504, A JP, 10-235782, A JP-A-64-82931 JP, 2008-2799687, A

  By the way, from the viewpoint of stabilizing the quality of the designed steel sheet, it has been required to lower the heating temperature for softening the adhesive as much as possible. That is, it has been required that the adhesive force of the adhesive during the production of the design steel sheet (such an adhesive force is also referred to as a primary adhesive force) be expressed at a temperature as low as possible. This is because if the heating temperature for softening the adhesive is too high, the design given to the design film deteriorates (that is, the quality of the design steel sheet deteriorates). Specifically, a large amount of heat is conducted to the design film in contact with the high-temperature adhesive, and the heat causes the pigment in the design film to volatilize. Moreover, the unevenness of the emboss becomes shallow due to the heat (so-called emboss return). In particular, in recent years, the design imparted to the design film tends to become more sophisticated, so that stabilizing the quality of the designed steel sheet has been a very important issue. Further, from the viewpoint of energy saving and improvement of productivity, it has been required to lower the heating temperature as much as possible. The lower the heating temperature, the shorter the time required for heating, and therefore the productivity (production speed) of the designed steel sheet is improved. In the design steel sheets disclosed in Patent Documents 1, 2, 7, and 8, since the heating temperature for softening the adhesive can be lowered, it is possible to suppress the deterioration of the design when manufacturing the design steel sheet.

  On the other hand, as described above, the designed steel plate is particularly often applied to the wall of the residential bathroom. Residential bathrooms are extremely harsh environments of high temperature and high humidity, but design steel sheets maintain the adhesion between the design film and steel sheets for a long time (for example, 5 years or more) even under such harsh environments. It was required to be possible. That is, the adhesive force of the adhesive agent after the design steel sheet is manufactured (such an adhesive force is also referred to as a secondary adhesive force) is obtained when the design steel sheet is used for a long period of time in a high temperature and high humidity environment. Was also required to be maintained at a high value.

  The present inventor has verified whether or not the design steel sheets disclosed in Patent Documents 1, 2, 7, and 8 can be applied to a high temperature and high humidity environment. Specifically, the design steel sheets disclosed in Patent Documents 1, 2, 7, and 8 were produced, and an acceleration test was performed using these design steel sheets. Here, the accelerated test is to immerse the designed steel sheet in boiling water for 2 hours. As a result, the adhesive layer was easily peeled off at the interface with the steel sheet. Therefore, the design steel sheets disclosed in Patent Documents 1, 2, 7, and 8 cannot be applied to high temperature and high humidity environments.

  In the above-mentioned accelerated test, the factors of "high temperature" and "water" act on the designed steel sheet. Therefore, in the above-mentioned accelerated test, it is not known which factor is causing the decrease in adhesion. Therefore, the present inventor conducted the following accelerated test in order to individually verify these factors. Specifically, the present inventor performed an accelerated test of heating a design steel sheet to 100 ° C. in a vacuum as an accelerated test related to high temperature. As a result, no change in adhesion was found before and after the accelerated test. Therefore, the inventor conducted an accelerated test of immersing the design steel sheet in water at 40 ° C. for 2 hours as an accelerated test on water. As a result, no change in adhesion was found before and after the accelerated test. Therefore, the present inventor conducted an accelerated test in which the design steel sheet was immersed in water at 60 ° C. and 80 ° C. for 2 hours, respectively, as an accelerated test combining high temperature and water. As a result, the adhesion was significantly reduced before and after the accelerated test. Specifically, the adhesive layer was easily peeled off at the interface with the steel sheet. As a result of the above, the present inventor found out that “water” and “high temperature” are the causes of the decrease in adhesion.

  Further, the present inventor produced the design steel sheets disclosed in Patent Documents 3 to 6 and performed the same acceleration test as described above (that is, the acceleration test of immersing the design steel sheet in boiling water for 2 hours). As a result, almost no change in adhesion was observed before and after the accelerated test. Therefore, the designed steel sheets disclosed in Patent Documents 3 to 6 can be adapted to a high temperature and high humidity environment.

  Then, in the designed steel sheets disclosed in Patent Documents 1, 2, 7, and 8, the adhesive that contacts the steel sheet softens at low temperature. On the other hand, in the designed steel sheets disclosed in Patent Documents 3 to 6, the adhesive that contacts the steel sheet softens at high temperature. Therefore, when the adhesive that contacts the steel sheet softens at low temperature, the design steel sheet cannot be adapted to high temperature and high humidity environment, but when the adhesive that contacts the steel sheet softens at high temperature, the design steel sheet does not adapt to high temperature and high humidity environment. You will be able to adapt. The present inventor believes that the reason is the difference in softening degree between the two adhesives.

  Graphs L1 and L2 shown in FIG. 1 are graphs showing the correspondence between the temperature and the softening degree of different adhesives. The adhesive having the characteristics shown in the graph L1 (hereinafter, also referred to as “adhesive A”) is one type of adhesive that softens at a low temperature, and the adhesive having the characteristics shown in the graph L2 (hereinafter referred to as “adhesion”). Agent B ") is one type of adhesive that softens at high temperatures. The degree of softening is measured by a thermomechanical analysis device (Thermal Mechanical Analysis). Specifically, the softening degree is obtained by pushing a small-diameter cylindrical needle into a sample with a predetermined load and dividing the penetration depth of the cylindrical needle at that time by the penetration depth at a predetermined temperature. The softening degree in FIG. 1 is obtained by dividing the penetration depth measured by pushing a cylindrical needle having a diameter of 1 mm into the sample with a load of 500 mN while heating the sample at 2 ° C./minute, and the penetration depth at 200 ° C. This is the value that can be obtained. The penetration depth of the cylindrical needle into the sample is measured according to JIS-K-7196. Further, the vertical axis of FIG. 1 is given a negative sign to the softening degree for easy understanding.

  The softening degree of the adhesive A sharply increases from around 40 ° C. and softens to 0.7 or more at a temperature of 60 ° C. or more. On the other hand, the softening degree of the adhesive B is maintained at a low value up to around 80 ° C. Here, increasing the softening degree of the adhesive means increasing the free volume of the adhesive. Then, as the free volume of the adhesive increases, water molecules are more likely to diffuse and penetrate into the adhesive. Therefore, when the adhesive A is heated to 60 ° C. or higher, a large amount of water molecules penetrate into the adhesive A. On the other hand, even if the adhesive B is heated in the same manner, the penetration amount of water molecules becomes lower than that of the adhesive A.

  Since the adhesives disclosed in Patent Documents 1 and 2 are softened at low temperatures, they have the same characteristics as the adhesive A. Therefore, when the design steel sheets disclosed in Patent Documents 1 and 2 are exposed to a high temperature and high humidity environment, a large amount of water molecules enter into the adhesive layer. It is considered that these water molecules break the chemical bond formed at the steel plate / adhesive layer interface. That is, since the steel sheet and the adhesive layer are bonded by dehydration condensation, this bond is hydrolyzed by water molecules that have penetrated into the adhesive layer. Further, since the adhesive layer is plasticized and embrittled by water molecules, this is also considered to be the cause of the decrease in adhesion. For these reasons, it is considered that when the design steel sheets disclosed in Patent Documents 1 and 2 are exposed to a high temperature and high humidity environment, the adhesive layer easily peels off at the interface with the steel sheet. That is, it is considered that the secondary adhesion cannot be maintained under the environment of high temperature and high humidity. On the other hand, the adhesives disclosed in Patent Documents 3 to 6 are softened at a high temperature and thus have the same characteristics as the adhesive B. Therefore, when the design steel sheets disclosed in Patent Documents 3 to 6 are exposed to a high temperature and high humidity environment, the penetration of water molecules into the adhesive layer is suppressed. Therefore, it is considered that the secondary adhesive force is maintained even in a hot and humid environment.

  On the other hand, in the design steel sheets disclosed in Patent Documents 7 and 8, the adhesive forming the lower adhesive layer has the same characteristics as the adhesive A, and the adhesive forming the upper adhesive layer is the adhesive. It has the same characteristics as B. Therefore, the upper adhesive layer functions as a barrier layer against water molecules. Therefore, the invasion of water molecules from the design film side to the lower adhesive layer can be suppressed. However, since the lower adhesive layer is exposed at the end surface of the designed steel sheet, a large amount of water molecules penetrate from this portion. Then, the water molecules that have penetrated into the lower adhesive layer break the chemical bonds formed at the steel plate / adhesive layer interface. Therefore, the design steel sheets disclosed in Patent Documents 7 and 8 cannot maintain the secondary adhesive force under the high temperature and high humidity environment.

  As described above, the design steel sheets disclosed in Patent Documents 3 to 6 can maintain the secondary adhesive force even in an environment of high temperature and high humidity. However, in order to develop the primary adhesion, it was necessary to heat the adhesive layer to a high temperature when producing the designed steel sheet. For this reason, there is a possibility that the design applied to the design film during the production of the design steel sheet may be significantly deteriorated. Therefore, it is possible to suppress the deterioration of the design applied to the design film during the production of the design steel plate, and to maintain the adhesion between the design film and the steel plate even under the severe environment of high temperature and high humidity. No feasible designed steel sheet has been proposed.

  Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to suppress the deterioration of the design applied to the design film during the production of the design metal plate, and, It is an object of the present invention to provide a new and improved design metal plate capable of maintaining the adhesion between the design film and the metal plate even under a severe environment of high temperature and high humidity, and a manufacturing method thereof.

  In order to solve the above problems, according to an aspect of the present invention, a metal plate, a lower layer side adhesive layer laminated on the metal plate, an upper layer side adhesive layer laminated on a lower layer side adhesive layer, an upper layer A design film laminated on the side adhesive layer, the lower layer side adhesive layer contains a lower layer side adhesive, the upper layer side adhesive layer contains an upper layer side adhesive, and the softening temperature of the upper layer side adhesive is 80. Provided is a design metal plate, which has a softening temperature of 90 ° C. or lower and a softening temperature of the lower layer side adhesive is 90 ° C. or higher.

  Here, the softening temperature of the upper layer side adhesive may be 70 ° C. or lower.

  The softening temperature of the lower layer side adhesive may be 100 ° C or higher.

  Further, the lower layer side adhesive and the upper layer side adhesive may be composed of any one or more of polyester, acrylic, urethane, epoxy, and urea thermosetting adhesives.

  In addition, the lower layer side adhesive and the upper layer side adhesive are polyester systems in which 3 to 25 parts by mass of a polyisocyanate resin having an isocyanate group in an amount of 30 mol% or more based on all dicarboxylic acid residues is added to 100 parts by mass of a linear polyester resin. It may be a thermosetting adhesive.

  Further, the lower adhesive layer may contain a silane coupling agent in an amount of 2 to 15 parts by mass with respect to 100 parts by mass of the lower adhesive.

  The design film may be made of any one or more of vinyl chloride resin, polyester resin, acrylic resin, polyolefin resin, and fluorine resin.

  Further, the softening temperature of the portion of the design film that is in contact with the upper adhesive layer may be less than 150 ° C.

  According to another aspect of the present invention, there is provided a method for producing a design metal sheet for producing the above-mentioned design metal sheet, which comprises a metal sheet at 180 ° C. or lower and a design film via a lower layer side adhesive layer and an upper layer side adhesive layer. There is provided a method for manufacturing a designed metal plate, which is characterized in that the metal plate is adhered.

  According to another aspect of the present invention, by laminating the lower layer side adhesive on the metal plate, a step of forming the lower layer side adhesive layer on the metal plate, and by heating the metal plate, the lower layer side adhesive layer To a metal plate, a step of forming an upper adhesive layer on the lower adhesive layer by laminating an upper adhesive on the lower adhesive layer, and a heating temperature of the metal plate of 180 ° C. or lower. Including the step of softening the upper-layer-side adhesive by heating up to 40 ° C., and the step of laminating the design film on the upper-layer-side adhesive layer, and the softening temperature of the upper-layer-side adhesive is 80 ° C. or lower. A softening temperature of the agent is 90 ° C. or higher, and a method for producing a designed metal plate is provided.

  According to another aspect of the present invention, by laminating the lower layer side adhesive on the metal plate, a step of forming the lower layer side adhesive layer on the metal plate, and by heating the metal plate, the lower layer side adhesive layer The step of bringing the metal plate into close contact with the metal plate, a step of preparing a laminated film in which the upper adhesive layer containing the upper adhesive is laminated on the design film, and the metal plate having a temperature of 180 ° C. or lower. A step of laminating the upper lower side adhesive layer and the upper layer side adhesive layer on the design film, wherein the softening temperature of the upper layer side adhesive is 80 ° C. or lower, and the softening temperature of the lower layer side adhesive is 90 ° C. or higher. A method for manufacturing a designed metal plate is provided.

  Here, the step of preparing the laminated film, by laminating the upper layer side adhesive on the design film, the step of forming the upper layer side adhesive layer on the design film, and by heating the design film, the upper layer side adhesion The step of bringing the layer into close contact with the design film may be included.

  Further, by laminating a lower layer side adhesive composition containing a lower layer side adhesive and a solvent on a metal plate to form a lower layer side adhesive layer, and heating the metal plate, a solvent contained in the lower layer side adhesive layer. May be evaporated and the lower adhesive layer may be brought into close contact with the metal plate.

  The lower adhesive layer may be brought into close contact with the metal plate by heating the metal plate to a heating temperature higher than 180 ° C.

  The softening temperature of the upper layer side adhesive may be 70 ° C. or lower.

  The softening temperature of the lower layer side adhesive may be 100 ° C or higher.

  Further, the lower layer side adhesive and the upper layer side adhesive may be composed of any one or more of polyester, acrylic, urethane, epoxy, and urea thermosetting adhesives.

  In addition, the lower layer side adhesive and the upper layer side adhesive are polyester systems in which 3 to 25 parts by mass of a polyisocyanate resin having an isocyanate group in an amount of 30 mol% or more based on all dicarboxylic acid residues is added to 100 parts by mass of a linear polyester resin. It may be a thermosetting adhesive.

  Moreover, the lower layer side adhesive layer is formed by laminating the lower layer side adhesive composition containing the lower layer side adhesive agent and the silane coupling agent on the metal plate, and the silane coupling agent is the lower layer side adhesive agent 100 parts by mass. 2 to 15 parts by mass may be included in the lower layer side adhesive composition.

  The design film may be made of any one or more of vinyl chloride resin, polyester resin, acrylic resin, polyolefin resin, and fluorine resin.

  Further, the softening temperature of the portion of the design film that is in contact with the upper adhesive layer may be less than 150 ° C.

  As described above, according to the present invention, it is possible to suppress the deterioration of the design applied to the design film at the time of manufacturing the design metal plate, and even under the severe environment of high temperature and high humidity, with the design film. The adhesion with the metal plate can be maintained.

It is a side view which shows the schematic structure of the design metal plate which concerns on embodiment of this invention. It is a graph which shows the correspondence of the temperature of an adhesive agent, and a softening degree. It is a side view which shows an example of the manufacturing apparatus of a design metal plate. It is a side view which shows the other example of the manufacturing apparatus of a design metal plate.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In this specification and the drawings, components having substantially the same functional configuration are designated by the same reference numerals, and duplicate description will be omitted.

<1. Design of metal plate>
First, the structure of the design metal plate 10 according to the embodiment of the present invention will be described with reference to FIG. The design metal plate 10 includes a metal plate 20, a design film 30, and an adhesive layer 40. The adhesive layer 40 includes a lower layer side adhesive layer 41 laminated on the metal plate 20 and an upper layer side adhesive layer 42 laminated on the lower layer side adhesive layer 41. Therefore, the adhesive layer 40 has a two-layer structure. The design film 30 is laminated on the upper adhesive layer 42.

(1-1. Structure of steel plate)
The type of the metal plate 20 is not particularly limited, and widely known metal plates can be used. Examples of the metal plate 20 include a steel plate, a stainless plate, an Al plate, a Cu plate, a brass plate, a Ti plate, a chrome plate, a nickel plate, a zinc plate, and a magnesium plate.

  Here, examples of the steel sheet include tin plate, thin tin-plated steel sheet, electrolytic chromic acid-treated steel sheet (tin-free steel sheet), can steel sheet such as nickel-plated steel sheet, hot-dip galvanized steel sheet, hot-dip zinc-iron alloy-plated steel sheet, Hot-dip zinc-aluminum-magnesium alloy-plated steel sheet, hot-dip aluminum-silicon alloy-plated steel sheet, hot-dip lead-tin alloy-plated steel sheet, etc. , Electroplated steel sheets such as electrogalvanized zinc-chromium alloy plated steel sheets, cold rolled steel sheets and the like. The steel sheet may be coated on one side or both sides.

  The surface of the steel sheet may be subjected to various chemical conversion treatments for the purpose of enhancing adhesion with the adhesive layer 40 and improving rust prevention. Specific examples of the chemical conversion treatment include electrolytic chromate treatment, phosphoric acid chromate treatment, coating chromate treatment containing hexavalent chromium, cobalt, molybdenum-based composite plating treatment, various inorganic coatings (for example, vanadium, titanium, zirconium, aluminum, magnesium). , A phosphorus-containing inorganic film), a process of coating various organic films (for example, an organic film containing polyacrylic acid resin, urethane resin, acrylic resin, etc.), a process of coating a silane coupling agent, etc. Can be mentioned.

  In this embodiment, since the lower layer side adhesive (the adhesive contained in the lower layer side adhesive layer 41) is softened at a high temperature, it is possible to suppress the entry of water molecules into the lower layer side adhesive layer 41. Therefore, even under an environment of high temperature and high humidity, the adhesive force (secondary adhesive force) at the interface between the metal plate 20 and the lower adhesive layer 41 can be maintained.

(1-2. Design film)
The type of the design film 30 is not particularly limited, and any design film used for a conventional design metal plate can be used as the design film 30 of the present embodiment. As described above, the design film 30 is provided with various designs (for example, color, pattern, emboss, etc.). Examples of the design film 30 include a monochromatic design film and a patterned design film. The monochromatic design film is a design film that is colored with a pigment. The surface of a monochromatic design film is often embossed. Light reflection is suppressed by such embossing. The patterned design film is a design film that is colored with a pigment and printed with a pattern. A transparent protective film for protecting the pattern may be further laminated on the surface of the patterned design film. Further, the patterned design film may be produced by pressure-bonding a colored film colored with a pigment and a transparent protective film on which a pattern is printed. In this case, the pattern-printed surface of the transparent protective film faces the colored film side.

  In this embodiment, the upper layer side adhesive (the adhesive contained in the upper layer side adhesive layer 42) softens at a low temperature. Therefore, the design film 30 can be sufficiently adhered to the upper layer side adhesive layer 42 even if the heating temperature for softening the upper layer side adhesive is low. That is, the design film 30 can be sufficiently adhered to the metal plate 20. Therefore, the design film 30 can be sufficiently adhered to the metal plate 20 while suppressing deterioration of the design applied to the design film 30.

(1-2-1. Resin that constitutes the design film)
The resin forming the design film 30 is not particularly limited. That is, any resin applicable to the conventional design film can be applied to the design film 30 of the present embodiment. Examples of the resin forming the design film 30 include a thermoplastic resin and a thermosetting resin. Examples of the thermoplastic resin include vinyl chloride resin, polyester resin, acrylic resin, polyolefin resin, and fluorine resin. Examples of thermosetting resins include urethane resins, urea resins, and epoxy resins. The design film 30 is preferably made of any one or more of the above-mentioned resins selected from vinyl chloride resin, polyester resin, acrylic resin, polyolefin resin, and fluorine resin. The design film 30 made of these resins is excellent in the wettability of printing and the embossing property, so that it is easy to give a high-level design. Hereinafter, examples of preferable resins will be described in detail.

  Vinyl chloride resin is a resin containing a monomer unit containing chlorine. Examples of the vinyl chloride resin include polyvinyl chloride, chlorinated polyvinyl chloride, polyvinylidene chloride, chlorinated polyethylene, vinyl chloride-vinyl acetate copolymer, vinyl chloride-ethylene copolymer, vinyl chloride-propylene copolymer. , Vinyl chloride-styrene copolymer, vinyl chloride-isobutylene copolymer, vinyl chloride-vinylidene chloride copolymer, vinyl chloride-styrene-maleic anhydride terpolymer, vinyl chloride-styrene-acrylonitryl copolymer Polymer, vinyl chloride-butadiene copolymer, vinyl chloride-isoprene copolymer, vinyl chloride-chlorinated propylene copolymer, vinyl chloride-vinylidene chloride-vinyl acetate terpolymer, vinyl chloride-maleic acid ester copolymer Coal, vinyl chloride-methacrylic acid copolymer, vinyl chloride-acrylonitrile copolymer -Containing resins, chlorine-containing resins such as vinyl chloride-various vinyl ether copolymers, and blended products thereof or synthetic resins containing no chlorine and other chlorine, such as acrylonitrile-styrene copolymers and ethylene-vinyl acetate copolymers , Ethylene-ethyl (meth) acrylate copolymers, blended products with polyesters, block copolymers, graft copolymers, and the like.

  Further, when the design film 30 containing a vinyl chloride resin as a main component is manufactured, the design film 30 contains a diene resin containing no chlorine, MBS (methyl methacrylate butadiene styrene) for the purpose of improving impact resistance, weather resistance and the like. Acrylic impact modifiers such as copolymers) and MBA (methyl methacrylate-butyl acrylate copolymer), chlorine-free resins such as acrylic resins and fluororesins may be added. In the present embodiment, the “main component” of the design film 30 means a material contained in the design film 30 in a mass ratio of 50 mass% or more with respect to the total mass of the design film 30. The addition amount of these additives is preferably less than 50 mass% with respect to the total mass of the design film 30. When the amount of the additive added is 50% by mass or more, the properties of the vinyl chloride resin may not be easily exhibited. Further, the addition amount of these additives is preferably 3% by mass or more based on the total mass of the design film 30. If it is less than 3% by mass, the film may be broken when an impact force is applied to the designed metal plate.

  Further, when the design film 30 containing a vinyl chloride resin as a main component is produced, a known plasticizer may be added to the design film 30 for the purpose of imparting flexibility and flexibility to the design film 30. Examples of additives include phthalate plasticizers such as diheptyl phthalate, dioctyl phthalate and diisononyl phthalate, adipate plasticizers such as dioctyl adipate, diisononyl adipate, di (butyldiglycol) adipate, and phosphates such as tricresyl phosphate. Examples thereof include plasticizers, polyester plasticizers, chlorinated paraffin plasticizers, trimellitate plasticizers, pyromellitate plasticizers, biphenyltetracarboxylate plasticizers and epoxy plasticizers. The addition amount of the plasticizer is preferably 30% by mass or less based on the total mass of the design film 30. When the added amount of the plasticizer is larger than 30% by mass, a large amount of the plasticizer may move to the surface when the designed metal plate 10 is used for a long time. In this case, the design property and the surface function may be deteriorated such that the surface is tacked. Further, the addition amount of the plasticizer is preferably 3% by mass or more based on the total mass of the costume film 30. If the amount is less than 3% by mass, the film is hard, and when the designed metal plate is processed, the film does not follow and cracks may occur.

  Further, when the design film 30 containing a vinyl chloride resin as a main component is produced, the design film 30 contains an organic acid such as barium stearate for the purpose of improving thermal stability, weather resistance, hiding power and impact resistance. Alkaline earth metal salts, organic acid zinc such as zinc stearate, 2,2,6,6-tetramethyl-4-piperidyl stearate, 1,2,2,6,6-pentamethyl-4-piperidyl stearate, Hindered amine compounds such as 2,2,6,6-tetramethyl-4-piperidyl benzoate and bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, and UV absorbers such as 2,4-dihydroxybenzophenone May be added. The addition amount of these additives is preferably 0.01 to 10 mass% with respect to the total mass of the design film 30. If the added amount is less than 0.01% by mass, the function of the additive may not be sufficiently exhibited. On the other hand, if the addition amount is more than 10% by mass, coloring or burning may occur.

  In the case of producing the design film 30 containing a vinyl chloride resin as a main component, a pigment such as rutile-type titanium dioxide or calcium carbonate is added to the design film 30 for the purpose of providing the design film 30 with hiding power. Good. The amount of the pigment added is preferably 1 to 30 mass% with respect to the total mass of the decorative film 30. When the addition amount is less than 1% by mass, the hiding property may be insufficient. If the addition amount is more than 30% by mass, the design film 30 may become brittle and film formation may be difficult. From the viewpoint of film-forming property and stability of hiding, the addition amount of the pigment is more preferably 5 to 20% by mass.

  When the design film 30 containing a vinyl chloride resin as a main component is manufactured, the design film 30 contains, as additives other than those described above, diphenylthiourea, diphenylurea, anilinodithiotriazine, melamine, benzoic acid, cinnamic acid, p. -A stabilizer such as tert-butylbenzoic acid or zeolite may be added. The design film 30 includes, if necessary, a cross-linking agent, a foaming agent, an antistatic agent, an antifogging agent, a plateout preventing agent, a surface treatment agent, a lubricant, a flame retardant, a fluorescent agent, a mildewproofing agent, a bactericide, and a metal. You may add additives, such as an inactive agent, a mold release agent, a pigment, a processing aid, an antioxidant, and a light stabilizer. The addition amount of these is preferably 0.1 to 5 mass% with respect to the total mass of the design film 30. When the added amount is 0.1% by mass, the function of the additive may not be sufficiently exhibited. When the addition amount is more than 5% by mass, the mechanical strength and other characteristics of the design film 30 may deteriorate.

  Examples of the polyester resin include a polyester resin composed of a diol compound residue and a dicarboxylic acid compound residue, or a polyester resin obtained by substituting a part or all of these with a hydroxylcarboxylic acid compound residue. More specific examples include PET (polyethylene terephthalate), PBT (polybutylene terephthalate), PET-I, PBT-I, PET-G, PCT-G, PAr (polyarylate), and those containing these as the main components. Polymer resins, mixtures of two or more of these, and the like can be mentioned.

  Here, PET-I is obtained by changing a part of the dicarboxylic acid residue of PET into an isophthalic acid residue. PBT-I is obtained by changing a part of the dicarboxylic acid residue of PBT to an isophthalic acid residue. PET-G is obtained by replacing a part of the diol residue of PET with 1,4-cyclohexanedimethanol (1,4-CHDM) residue, and the mole of 1,4-CHDM residue in the diol residue is The ratio is 20% or more and less than 50% with respect to the total number of moles of diol residues. PCT-G is obtained by replacing a part of the diol residue of PET with 1,4-CHDM residue, and the molar ratio of the 1,4-CHDM residue in the diol residue is the total mol of the diol residue. It is 50% or more and 80% or less of the number.

  The acrylic resin is a resin whose main component is acrylic acid ester or methacrylic acid ester. Examples of the acrylate ester include methyl acrylate, ethyl acrylate, butyl acrylate and the like. Examples of the methacrylic acid ester include methyl methacrylate, methyl methacrylate, butyl methacrylate and the like. When the design film 30 containing an acrylic resin as a main component is manufactured, an acrylic impact modifier such as MBS or MBA may be added to the design film 30 for the purpose of improving the processability of the design film 30.

  Examples of the polyolefin resin include polyethylene resin, polypropylene resin, ethylene-propylene copolymer resin and the like.

  Examples of the fluorine-based resin include PVF (polyvinyl fluoride), PVDF (polyvinylidene fluoride), PTFE (polytetrafluoroethylene), PFA (polytetrafluoroethylene), PFEP (hexafluoroethylene propylene), etc. In addition to the resin having a different fluorine skeleton, a copolymer of a fluorine-containing monomer and an olefin, a copolymer of a fluorine-containing monomer and a chlorine-containing monomer and the like can be mentioned. Examples of the copolymer of the fluorine-containing monomer and the olefin include ETFE (copolymer of tetrafluoroethylene and ethylene). Examples of the copolymer of the fluorine-containing monomer and the chlorine-containing monomer include PCTFE (polychlorotrifluoroethylene), ECTFE (copolymer of ethylene and chlorotrifluoroethylene), and the like.

  Among the resins listed above, a particularly preferable resin is vinyl chloride resin, PET, PBT, PET-G, PET-I, PBT-I, PVF, PVDF, an acrylic resin containing methyl methacrylate as a main component, Polyethylene resin and polypropylene resin. The design film 30 containing these resins as a main component is particularly excellent in print wettability and embossability and is also excellent in productivity.

(1-2-2. Softening temperature)
The softening temperature of the design film 30 is not particularly limited, but the softening temperature of the portion in contact with the upper adhesive layer 42 is preferably less than 150 ° C. Here, the softening temperature is measured by a thermomechanical analysis device (Thermal Mechanical Analysis). Specifically, while heating the sample at 2 ° C./minute, a cylindrical needle having a diameter of 1 mm is pushed into the sample with a load of 500 mN. Then, the temperature when the depth of penetration of the cylindrical needle into the sample satisfies the following mathematical expression (1) is defined as the softening temperature. The penetration depth of the cylindrical needle into the sample is measured according to JIS-K-7196.
t _i / t ₂₀₀ = 0.8 (1)
In Expression (1), t _i is the penetration depth, and t ₂₀₀ is the penetration depth when the sample temperature is 200 ° C. Therefore, the left side of Expression (1) indicates the softening degree.

  When the softening temperature of the portion in contact with the upper adhesive layer 42 (hereinafter, also referred to as “adhesive layer contact portion”) is less than 150 ° C., the design film 30 and the upper layer side are suppressed while suppressing deterioration of the design during the production of the design metal plate. The adhesion with the adhesive layer 42 can be improved. That is, since the adhesive layer contact portion is sufficiently softened even when heated to a temperature of 180 ° C. or less, the adhesive force with the upper adhesive layer 42 can be improved. In other words, the adhesive layer contact portion can exert a sufficient anchor effect. Moreover, since the heating temperature of the design film 30 is 180 ° C. or lower, deterioration of the design is suppressed.

  Examples of the resin having a softening temperature of less than 150 ° C. include the above-mentioned PET, PBT-I, PET-G, acrylic resin containing methyl methacrylate as a main component, polyethylene resin and the like. Therefore, the adhesive layer contact portion may be formed of these resins.

(1-2-3. Thickness of Design Film)
The thickness of the design film 30 is not particularly limited. However, from the viewpoint of effectively utilizing the effects of the present embodiment, the thickness of the design film 30 is preferably 5 to 400 μm, and more preferably 5 to 150 μm.

  The adhesives disclosed in Patent Documents 3 to 6 soften at high temperatures. That is, these adhesives are unlikely to exhibit the anchor effect unless the heating temperature is raised. Therefore, it is necessary to press-bond the design film to the high-temperature adhesive layer when manufacturing the design metal plate. Therefore, when the thickness of the design film is less than 80 μm, a large amount of heat is conducted to the surface of the design film when the design film is pressure-bonded to the adhesive layer. Then, this heat deteriorates the design of the design film surface. Therefore, in order to maintain the design applied to the design film, the thickness of the design film needs to be 80 μm or more. However, if the thickness of the design film is 200 μm or more, a large thermal stress is generated due to the difference in thermal expansion between the steel plate and the design film when the design film is pressure-bonded to the steel plate. As a result, the adhesive strength of the adhesive is reduced. In addition, the design film may be warped.

  On the other hand, in the present embodiment, the upper layer side adhesive contained in the upper layer side adhesive layer 42 (that is, the adhesive layer on the design film 30 side) is softened at a low temperature. Therefore, in the present embodiment, even if the upper adhesive layer 42 is at a low temperature, the upper adhesive layer 42 and the design film 30 can be sufficiently brought into close contact with each other. That is, the heat conducted to the design film 30 can be reduced. Therefore, even if the thickness of the design film 30 is less than 80 μm, deterioration of the design applied to the design film 30 can be suppressed. Further, since the heat conducted to the design film 30 can be reduced, the stress generated by the difference in thermal expansion between the metal plate 20 and the design film 30 even if the thickness of the design film 30 is 200 μm or more. Can be made smaller. That is, even if the thickness of the design film 30 is 200 μm or more, it is possible to suppress the decrease in adhesion and the warp of the design film 30. However, when the thickness of the design film 30 is less than 5 μm, heat may be conducted to the surface of the design film 30 and the design may be deteriorated. If the thickness of the design film 30 exceeds 400 μm, the manufacturing cost of the design film 30 may increase. Therefore, the thickness of the design film 30 is preferably 5 to 400 μm.

(1-3. Structure of adhesive layer)
The adhesive layer 40 includes a lower adhesive layer 41 and an upper adhesive layer 42. The lower adhesive layer 41 is in close contact with the metal plate 20, and the upper adhesive layer 42 is in close contact with the design film 30. The lower layer side adhesive layer 41 contains a lower layer side adhesive agent, and the upper layer side adhesive layer 42 contains an upper layer side adhesive agent. The softening temperature (T _under ) of the lower layer side adhesive is 90 ° C. or higher, and the softening temperature (T _up ) of the upper layer side adhesive is 80 ° C. or lower. When the adhesive is a thermosetting adhesive, the softening temperature of the adhesive is defined as the value measured with a film made of only the adhesive main agent containing no curing agent.

  In this way, the upper layer side adhesive is sufficiently softened at a low temperature (for example, a temperature of 180 ° C. or lower), and therefore even when the low temperature upper layer side adhesive layer 42 and the design film 30 are brought into close contact with each other, the upper layer side adhesive is adhered. The anchor effect of the agent on the design film 30 can be sufficiently exhibited. That is, the upper layer side adhesive penetrates deep into the unevenness of the design film 30 and can secure a sufficient contact area with the design film 30. As a result, the design film 30 and the upper adhesive layer 42 can be brought into close contact with each other with a sufficiently strong adhesive force that can withstand bending and overhanging. Moreover, since the heat conducted to the design film 30 can be reduced, deterioration of the design applied to the design film 30 can be suppressed.

  Furthermore, since the lower layer side adhesive softens at a high temperature, even if the design metal plate 10 is exposed to a high temperature and high humidity environment for a long period of time, it is possible to suppress the penetration of water molecules into the lower layer side adhesive layer 41. Therefore, the chemical bond between the lower adhesive layer 41 and the metal plate 20 can be maintained. Here, the lower adhesive layer 41 is exposed from the end surface of the design metal plate 10, but the intrusion of water molecules from this exposed surface is also suppressed. Since the upper adhesive layer 42 is exposed at the end surface of the design metal plate 10, water molecules may enter the upper adhesive layer 42 from the end surface. However, since water molecules in the upper adhesive layer 42 cannot penetrate into the lower adhesive layer 41, they cannot reach the interface between the lower adhesive layer 41 and the metal plate 20. In addition, it is estimated that the water molecules in the upper adhesive layer 42 do not affect the bonding at the interface between the upper adhesive layer 42 and the design film 30. This is because the peeling of the design film 30 occurs at the interface between the steel sheet and the adhesive layer by the accelerated test by the present inventors. Therefore, even when the design metal plate 10 is exposed to the environment of high temperature and high humidity for a long period of time, the secondary adhesion can be maintained for a long period of time.

  As described above, according to the present embodiment, it is possible to suppress the deterioration of the design applied to the design film 30 when the design metal plate 10 is manufactured, and to design even under a severe environment of high temperature and high humidity. The adhesive force between the film 30 and the metal plate 20 can be maintained. Therefore, the design film 30 can be manufactured with little consideration given to the influence of heat on the design film 30 (for example, deterioration of the design). That is, as described above, it is necessary to form the adhesive layer using an adhesive having a high softening temperature from the viewpoint of maintaining the secondary adhesion of the designed metal plate in a high temperature and high humidity environment. However, in this case, it is necessary to pressure-bond the design film to the high-temperature adhesive layer. Therefore, the influence of heat on the design film is very large. Therefore, when producing a design film, it is necessary to consider such an influence of heat. For example, it is necessary to perform work such as selecting a material having high heat resistance and increasing the thickness of the design film. However, in the present embodiment, the upper adhesive layer 42 that is pressure bonded to the design film 30 is made of an adhesive having a low softening temperature. Therefore, when manufacturing the design film 30, it is almost unnecessary to consider the influence of heat. For this reason, for example, the range of choices of materials is expanded. Further, as described above, the thickness of the design film 30 can be selected from a wider range of values.

  Here, the softening temperature of the upper layer side adhesive is preferably 70 ° C. or lower. In this case, the upper layer side adhesive is sufficiently softened even at a low heating temperature such as 165 ° C. or lower. Therefore, even when the upper adhesive layer 42 heated to this temperature and the design film 30 are brought into close contact with each other, the anchor effect of the upper adhesive to the design film 30 can be sufficiently exhibited.

  The softening temperature of the lower layer side adhesive is preferably 100 ° C. or higher. In this case, even in an extremely harsh environment in which the design metal plate 10 is immersed in hot water, it is possible to prevent water molecules from penetrating into the lower adhesive layer 41. Therefore, the secondary adhesion can be maintained for a long period of time even under such an extremely harsh environment. Further, the difference between the softening temperature of the lower layer side adhesive and the softening temperature of the upper layer side adhesive is preferably 30 ° C. or more. In this case, a strong secondary adhesive force can be exhibited while more stably holding the design applied to the design film.

(Specific example of 1-3-1. Adhesive)
The adhesive constituting the lower layer side adhesive and the upper layer side adhesive may be any as long as it satisfies the above-mentioned softening temperature condition. Examples of the adhesive constituting the lower layer side adhesive and the upper layer side adhesive include a solvent type adhesive, a water-based adhesive, a hot melt type adhesive, an elastic adhesive, a thermosetting type (thermosetting reaction type) adhesive, Examples include pressure sensitive adhesives and natural product adhesives.

  Examples of solvent-based adhesives include rubber-based adhesives and resin-based adhesives. Here, examples of the rubber-based adhesive include natural rubber (polyisoprene) -based, butyl rubber-based, and styrene-butadiene rubber-based adhesives. Examples of the resin adhesive include vinyl acetate resin adhesive, urethane resin adhesive, ethylene vinyl acetate copolymer resin adhesive, and the like.

  Examples of water-based adhesives include water-soluble adhesives, emulsion adhesives, latex adhesives and the like. Examples of the water-soluble adhesive include starch paste, Poval paste, aqueous polymer-isocyanate adhesive, polyvinylpyrrolidone adhesive, gum arabic adhesive and the like. Examples of the emulsion adhesive include emulsion adhesives such as vinyl acetate resin emulsion, EVA resin emulsion, acrylic emulsion and urethane emulsion. Examples of the latex adhesive include a latex adhesive made of rubber such as chloroprene rubber as a raw material.

  Examples of hot-melt adhesives include thermoplastic elastomer-based, EVA (ethylene vinyl acetate copolymer) -based, olefin-based, polyamide-based, urethane-based, polyester-based hot-melt adhesives and the like. Here, as an example of the thermoplastic elastomer hot melt adhesive, a thermoplastic elastomer hot melt adhesive containing a synthetic rubber such as SBS (styrene-butadiene-styrene) or SIS (styrene-isoprene-styrene) as a main component is used. An adhesive or the like may be used. Examples of the olefin-based hot-melt adhesive include an olefin-based hot-melt adhesive containing amorphous polypropylene as a main component.

  Examples of the elastic adhesive include a silicone-based adhesive containing siloxane as a main component, a modified silicone resin-based adhesive containing a modified silicone polymer obtained by introducing a hydrolyzable silyl group into various polyethers as a main component, and a silylated urethane adhesive. Agents and the like.

  Examples of thermosetting adhesives include epoxy resin adhesives obtained by crosslinking and condensing an epoxy resin with a curing agent, as well as urethane-based, urea-based, melamine-based, phenol-based, acrylic-based, cyanoacrylate-based, and polyester-based heats. A curing adhesive or the like can be used.

  Examples of pressure sensitive adhesives include acrylic, rubber, and silicon pressure sensitive adhesives. Examples of natural product adhesives include natural product adhesives composed of glue, gelatin, fibrin, water glass and the like.

  Among the adhesives listed above, particularly preferable adhesives are polyester-based, acrylic-based, urethane-based, epoxy-based, and urea-based thermosetting adhesives. These adhesives are easy to handle at the time of manufacturing the design metal plate 10, and have excellent affinity with the metal plate 20 and the design film 30 and excellent stability against heat and humidity. Further, among these adhesives, a polyester thermosetting adhesive is particularly preferable. This is because this adhesive is particularly excellent in handling properties, adhesion, and strength of the adhesive itself, in addition to the above characteristics. Hereinafter, the polyester thermosetting adhesive will be described in detail.

  As the polyester thermosetting adhesive, a polyester resin, a urethane-modified polyester resin obtained by blending a polyester diol with a polyisocyanate compound, and a base material mainly composed of an epoxy-modified polyester resin obtained by modifying a polyester diol with an epoxy resin are used as an isocyanate compound. , Blocked isocyanate compounds, and adhesives crosslinked with a crosslinking agent such as amino resin.

  Here, as an example of the polyester resin as the main component, a polyester resin having a dicarboxylic acid residue and a diol residue can be mentioned. Examples of the dicarboxylic acid residue are terephthalic acid residue, isophthalic acid residue, phthalic anhydride residue, aromatic carboxylic acid residue such as α- or β-naphthalenedicarboxylic acid residue, succinic acid residue and glutaric acid. Residues, adipic acid residues, pimelic acid residues, suberic acid residues, azelaic acid residues, sebacic acid residues, undecylenic acid residues and other aliphatic dicarboxylic acid residues, 1,4-cyclohexanedicarboxylic acid residues And alicyclic dicarboxylic acid residues such as tetrahydrophthalic anhydride residue and hexahydrophthalic anhydride residue. Examples of the diol residue include ethylene glycol residue, 1,4-butanediol residue, diethylene glycol residue, propylene glycol residue, 1,3-butylene glycol residue, 1,6-hexane glycol residue and trimethylpropanol residue. Groups, trimethylolethane residues and the like.

  In addition, examples of the polyester diol include polyester diols in which both ends of the polyester resin are hydroxyl groups. Examples of the polyisocyanate compound include diisocyanate compounds such as triresin isocyanate, diphenylmethane diisocyanate, naphthalene diisocyanate, and tetramethylene diisocyanate, and dimer or higher compounds thereof. Examples of the epoxy modified polyester resin include bisphenol A type or bisphenol F type epoxy modified polyester resin.

  Examples of the isocyanate compound that is crosslinked to the main component include an aliphatic, alicyclic, or aromatic di- or triisocyanate compound having two or more isocyanate groups. Specific examples of the isocyanate compound include polyphenylmethane diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, 4,4-dicyclohexylmethitadiisocyanate, triphenylmethane triisocyanate, and polymethylene polyphenylene polyisocyanate.

  Examples of blocked isocyanate compounds include isocyanates obtained by blocking each of the above isocyanate compounds with the following isocyanate blocking agents. Here, examples of the isocyanate blocking agent include phenol-based blocking agents such as phenol, thiophenol, methylthiophenol, cresol, xylenol, resorcinol, nitrophenol, and chlorophenol, oxime-based blocks such as acetoxime, methylethylketoxime, and cyclohexanone oxime. Agents, alcohol-based blocking agents such as methanol, ethanol, propanol, butanol, halogen-substituted alcohol-based blocking agents such as ethylene chlorohydrin and 1,3-dichloro-2-propanol, and t-butanol, t-pentanol and other Examples thereof include tertiary alcohol-based blocking agents, lactam-based blocking agents such as ε-caprolactam, δ-valerolactam, γ-butyrolactam, and β-propyllactam. Other examples of blocking agents include aromatic amines, imides, active methylene compounds such as acetylacetone, acetoacetic acid ester, and malonic acid ethyl ester, mercaptans, imines, ureas, diaryl compounds, sodium bisulfite, and the like. Can be mentioned.

  In addition, examples of the amino resin include amino resins obtained by a condensation reaction of a compound containing an amino group such as urea, melamine, and benzoguanamine with formaldehyde, and further, these amino resins and an alcohol having 1 to 6 carbon atoms. Examples thereof include alkyl ether compounds obtained by condensation reaction. More specific examples of the amino resin include methoxylated methylol urea, methoxylated methylol-N, N-ethylene urea, methoxylated methylol dicyandiamide, methoxylated methylol melamine, methoxylated methylol benzoguanamine, butoxylated methylol melamine, butoxylated methylol. Examples thereof include benzoguanamine.

In the polyester thermosetting adhesive, in order to accelerate the above-mentioned crosslinking reaction, an amine catalyst such as butylamine, hexylamine, oxylamine, BF ₃ (boron trifluoride) amine complex compound, 1,8- Diazabicyclo (5,4,0) undecene-7, imidazole and the like may be added. Among these additives, the tertiary amine having a large catalytic action is most preferable.

  Among the above polyester-based thermosetting adhesives, particularly preferred examples are polyisocyanates having 3 to 25 parts by mass of two or more isocyanate groups with respect to 100 parts by mass of a linear polyester resin composed of an aromatic dicarboxylic acid and a diol residue. It is a polyester thermosetting adhesive with addition of parts. This polyester thermosetting adhesive is particularly excellent in affinity with the metal plate 20 and the design film 30. Further, this polyester thermosetting adhesive has a strong self-cohesive force and a high strength of the adhesive itself, so that cohesive failure of the adhesive can be prevented.

  Further, by adding 3 parts by mass or more of polyisocyanate to the linear polyester resin, crosslinking can be further promoted during heating. Therefore, the cohesive force is further increased. Further, by adjusting the addition amount of the polyisocyanate to 25 parts by mass or less, it is possible to impart appropriate ductility to the polyester thermosetting adhesive. Therefore, the processability of the polyester thermosetting adhesive can be improved. When the pot life is required, it is preferable to use the blocked isocyanate in an amount of 80 parts by mass or more based on all isocyanate components.

  Here, as an example of the linear polyester resin, an aromatic carboxylic acid residue containing a terephthalic acid residue, and either an ethylene glycol residue, a neopentyl glycol residue, or a 2-methyl-1,3-propanediol residue is used. A linear polyester resin composed of a diol residue contained therein may be mentioned. Here, it is preferable that the linear polyester resin contains terephthalic acid residues in an amount of 30 mol% or more based on all dicarboxylic acid residues. When the content is less than 30 mol%, the cohesive force of the adhesive itself becomes insufficient. As a result, the proof stress against the residual stress due to the thermal strain applied during lamination is lowered. Therefore, when the design metal plate 10 is exposed to a high temperature and high humidity environment for a long period of time, the adhesive itself may break and peel off. Further, the linear polyester resin preferably contains the above-mentioned diol residues in an amount of 60 mol% or more based on all the diol residues. If the content is less than 60 mol%, the solubility of the polyester thermosetting adhesive in the solvent may be poor, and the adhesive concentration may not be constant in the pot.

  Various additives can be added to the adhesive layer 40. Examples of such additives include organic compounds, inorganic compounds, various pigments composed of metal oxides (for example, rust-preventive pigments, coloring pigments, extender pigments, etc.), benzophenone-based, benzotriazole-based, triazine-based, etc. UV absorbers, hindered amine-based light stabilizers, hindered phenol-based, phosphorus-based, sulfur-based, tocopherol-based and other antioxidants, epoxysilane-based, vinylsilane-based, mercaptosilane-based, aminosilane-based silane coupling agents , An adhesive agent such as a rosin resin, a xylene resin, an epoxy resin, super particles such as anhydrous silica, a flame retardant, a viscosity modifier, a coating film reinforcing agent, a defoaming agent, and a surface smoothing agent.

  In particular, it is preferable that a silane coupling agent is added to the lower adhesive layer 41 in order to enhance the adhesion with the metal plate 20. The addition amount of the silane coupling agent is preferably 2 to 15 parts by mass with respect to 100 parts by mass of the lower layer side adhesive. When the amount of the silane coupling agent added is less than 2 parts by mass, the effect of improving the adhesion to the metal plate 20 is small. If the addition amount of the silane coupling agent exceeds 15 parts by mass, the adhesion to the upper adhesive layer 42 may be reduced. Further, from the viewpoint of improving water-resistant adhesion, the silane coupling agent is preferably organized by reaction with maleic anhydride.

(1-3-2. Thickness of adhesive layer)
The layer thickness of the lower layer side adhesive layer 41 and the upper layer side adhesive layer 42 is not particularly limited. These thicknesses can be appropriately selected according to the characteristics required for the designed metal plate 10. However, the thickness of both layers is preferably 1 μm or more. If the thickness is less than 1 μm, the functions of each layer may not be efficiently exhibited. Further, from the viewpoint of economy, the thickness of each layer is preferably 20 μm or less.

(1-3-3. Layer structure)
One or a plurality of other adhesive layers may be interposed between the lower layer side adhesive layer 41 and the upper layer side adhesive layer 42.

<2. Manufacturing method of design metal plate>
The manufacturing method of the design metal plate 10 includes a step of laminating a design film on a steel plate, and a step of laminating an adhesive on the design film, in which case the temperature at which the design film is heated is 180 ° C. or lower. If there is, it is not particularly limited. In this embodiment, the design film is not heated to 180 ° C. or higher in the laminating step. Moreover, since the softening temperature of the upper layer side adhesive that constitutes the upper layer side adhesive layer 42 is 80 ° C. or lower, the upper layer side adhesive is sufficiently softened even if the temperature of the metal plate 20 is 180 ° C. or lower. Therefore, the design film 30 and the metal plate 20 can be firmly adhered. Specific examples of the method for manufacturing the designed metal plate 10 include the following first and second examples.

(2-1. First example)
In the first example, the design metal plate 10 is manufactured by the following steps. First, the lower layer side adhesive layer 41 is formed on the metal plate 20 by applying the lower layer side adhesive composition on the metal plate 20. Next, by heating the lower adhesive layer 41, the lower adhesive is brought into close contact with the metal plate 20. Here, the heating temperature of the metal plate 20 is not particularly limited as long as it is a temperature at which the lower layer side adhesive is brought into close contact with the metal plate 20. For example, as described above, the heating temperature may be adjusted depending on whether or not the lower adhesive layer 41 contains a solvent.

  Next, the upper layer side adhesive layer 42 is formed on the lower layer side adhesive layer 41 by applying the upper layer side adhesive composition on the lower layer side adhesive layer 41. Then, the metal plate 20 is heated to a heating temperature of 180 ° C. or lower to soften the upper layer side adhesive. Thus, in this embodiment, the heating temperature of the metal plate 20 is lowered. However, as described above, since the softening temperature of the upper layer side adhesive is low, the upper layer side adhesive is sufficiently softened even at such a heating temperature. Further, since the low-temperature upper adhesive layer 42 can be pressure-bonded to the design film 30, the heat conducted to the design film 30 can be reduced. Therefore, the deterioration of the design applied to the design film 30 can be suppressed. Then, the design film 30 is pressure-bonded to the upper adhesive layer 42. Thereby, the designed metal plate 10 is manufactured. The design metal plate 10 is appropriately cooled.

(2-2. Second example)
In the second example, the design metal plate 10 is manufactured by the following steps. First, the lower layer side adhesive layer 41 is formed on the metal plate 20 by applying the lower layer side adhesive composition on the metal plate 20. Next, by heating the metal plate 20, the lower layer side adhesive is brought into close contact with the metal plate 20. Here, the heating temperature of the metal plate 20 is not particularly limited as long as it is a temperature at which the lower layer side adhesive is brought into close contact with the metal plate 20. For example, as described above, the heating temperature may be adjusted depending on whether or not the lower adhesive layer 41 contains a solvent.

  On the other hand, the upper layer side adhesive layer 42 is formed on the design film 30 by applying the upper layer side adhesive composition on the design film 30. Then, by heating the design film 30, the upper adhesive layer 42 is brought into close contact with the design film 30. Here, the heating temperature of the design film 30 is a temperature at which the upper adhesive layer 42 adheres to the design film 30, that is, a temperature at which the upper adhesive develops an anchoring effect on the design film 30 and is 180 ° C. or less, in particular. There is no limit.

  Then, with the temperature of the metal plate 20 kept at 180 ° C. or lower, the upper adhesive layer 42 on the design film 30 is pressure-bonded to the lower adhesive layer 41 on the metal plate 20. The design metal plate 10 is manufactured by bonding the lower adhesive layer 41 and the upper adhesive layer 42 together. As described above, since the softening temperature of the upper layer side adhesive is low, the upper layer side adhesive is sufficiently softened even if the temperature of the metal plate 20 is 180 ° C. or lower. Further, since the low-temperature upper adhesive layer 42 can be pressure-bonded to the design film 30, the heat conducted to the design film 30 can be reduced. Therefore, the deterioration of the design applied to the design film 30 can be suppressed. The design metal plate 10 is appropriately cooled.

  The method for manufacturing the design metal plate 10 is not limited to the above-described first example and second example. That is, in the first example and the second example described above, the design metal plate 10 is continuously manufactured, but the design metal plate 10 may be manufactured by a badge type manufacturing method. For example, the metal plate 20 on which the lower layer side adhesive layer 41 and the upper layer side adhesive layer 42 are laminated may be cut out into a predetermined area and the design film 30 may be laminated on the metal plate 20 by a batch type thermocompression bonding apparatus.

<3. Configuration example of design metal plate manufacturing equipment>
(3-1. First example)
The first example of the manufacturing method is realized, for example, by using the manufacturing apparatus 100 shown in FIG. Therefore, the configuration of the manufacturing apparatus 100 will be described. Of course, the manufacturing apparatus for the design metal plate 10 is not limited to the manufacturing apparatus 100 shown in FIG. 3 and the manufacturing apparatus 101 described later. That is, any device may be used as long as it can manufacture the design metal plate 10 having the above-described structure. For example, in the manufacturing apparatuses 100 and 101 described below, each adhesive layer is formed by a roll coater method, but each adhesive layer is formed by another method, for example, a spray coating method, a dipping method, a method of laminating a film adhesive, or the like. It may be formed.

  The manufacturing apparatus 100 includes a transport device (not shown) for the metal plate 20, a first roll coater 120, a first oven 130, a second roll coater 140, a second oven 150, and a design film transport device 160. The pressure roll pair 163 and the cooling device 170 are provided.

  The transporting device for the metal plate 20 transports the metal plate 20 from the left end to the right end in FIG. The first roll coater 120 is a device that stacks the lower adhesive layer 41 on the metal plate 20, and includes a coater pan (pot) 121a, a pickup roll 122, an applicator roll 123, and a backup roll 124.

  The coater pan 121a is a device for storing the lower layer side adhesive composition 121 containing the lower layer side adhesive. The lower layer side adhesive composition 121 may contain a solvent in addition to the lower layer side adhesive, and may further contain an additive constituting the lower layer side adhesive layer 41. Here, the solvent is used for the purpose of adjusting the viscosity of the lower layer side adhesive, for example. Examples of the solvent include aromatic hydrocarbons such as benzene, toluene and xylene, ketones such as acetone, MEK (methyl ethyl ketone) and methylene isobutylene ketone, esters such as methyl acetate, ethyl acetate and butyl acetate, diethylene ether and THF. , Ethers such as dioxane, and mixtures thereof.

  The pickup roll 122 picks up the lower layer side adhesive composition 121 from the coater pan 121a and conveys it to the applicator roll 123. The applicator roll 123 forms the lower adhesive layer 41 on the metal plate 20 by applying the lower adhesive composition 121 to one surface of the metal plate 20. The backup roll 124 contacts the other surface of the metal plate 20 and holds the metal plate 20 together with the applicator roll 123. Then, the backup roll 124 conveys the metal plate 20 to the first oven 130.

  The first oven 130 heats the metal plate 20 to bring the lower adhesive layer 41 into close contact with the metal plate 20. Here, the heating temperature of the metal plate 20 is not particularly limited as long as it is a temperature at which the lower adhesive layer 41 adheres to the metal plate 20, that is, a temperature at which the lower adhesive exhibits an anchor effect on the metal plate 20.

  For example, when the lower layer adhesive composition does not contain a solvent, the heating temperature may be higher than 180 ° C. In this case, even if the softening temperature of the lower layer side adhesive is high, the lower layer side adhesive can be sufficiently softened. As a result, the lower layer side adhesive penetrates deep into the irregularities of the metal plate 20, and a strong anchor effect can be exhibited.

  On the other hand, when the lower adhesive layer 41 contains a solvent, the heating temperature may be a temperature at which the solvent evaporates. This is because by heating the metal plate 20 at such a heating temperature, the lower layer side adhesive can penetrate deep into the unevenness of the metal plate 20 and exhibit a strong anchoring effect. In this case, the heating temperature becomes lower, which is preferable. Further, in the manufacturing apparatus 100, the solvent is removed from the lower layer side adhesive layer 41 before the upper layer side adhesive layer 42 is formed by the second roll coater 140. Therefore, it is possible to prevent the components of the lower adhesive layer from entering the upper adhesive layer 42 when the upper adhesive layer 42 is manufactured.

  The second roll coater 140 is a device that stacks the upper adhesive layer 42 on the lower adhesive layer 41, and includes a coater pan (pot) 141a, a pickup roll 142, a transport roll 143, and an applicator roll 144. ..

  The coater pan 141a is a device for storing the upper layer side adhesive composition 141 containing the upper layer side adhesive. The upper layer side adhesive composition 141 may contain a solvent in addition to the upper layer side adhesive, and may further contain an additive constituting the upper layer side adhesive layer 42. Here, the solvent is used for the purpose of adjusting the viscosity of the upper layer adhesive. Examples of the solvent include the same examples as the solvent of the lower layer side adhesive composition 121 described above.

  The pickup roll 142 picks up the upper layer side adhesive composition 141 from the coater pan 141a and conveys it to the conveyance roll 143. The transport roll 143 transports the upper layer side adhesive composition 141 to the applicator roll 144. The transport roll 143 may be omitted. In the example of FIG. 4, the transport roll 143 is omitted. The applicator roll 144 forms the upper adhesive layer 42 on the lower adhesive layer 41 by applying the upper adhesive composition 141 on the lower adhesive layer 41.

  The second oven 150 heats the metal plate 20 to a heating temperature of 180 ° C. or lower to soften the upper layer side adhesive. Thus, in this embodiment, the heating temperature of the metal plate 20 is lowered. However, since the softening temperature of the upper layer side adhesive is low as described above, the upper layer side adhesive is sufficiently softened even at such a heating temperature. Further, since the low-temperature upper adhesive layer 42 can be pressure-bonded to the design film 30, the heat conducted to the design film 30 can be reduced. Therefore, the deterioration of the design applied to the design film 30 can be suppressed. The heating temperature of the metal plate 20 can be further lowered according to the softening temperature of the upper layer side adhesive. For example, when the softening temperature of the upper layer side adhesive is 70 ° C. or lower, the heating temperature of the metal plate 20 is preferably 165 ° C. or lower, and more preferably 140 ° C. or lower. When the softening temperature of the upper layer side adhesive is 70 ° C. or lower, the upper layer side adhesive is sufficiently softened even if the heating temperature is within the above range. That is, the design film 30 can be sufficiently adhered to the metal plate 20. Therefore, the design film 30 can be sufficiently adhered to the metal plate 20 while suppressing deterioration of the design applied to the design film 30. The lower limit of the heating temperature of the metal plate 20 may be the softening temperature of the upper layer side adhesive −40 ° C. If the heating temperature of the metal plate 20 falls below the temperature, the upper layer side adhesive may not be sufficiently softened in a short time when the design film is laminated, and the primary adhesive force may be reduced.

  The design film transport device 160 is a device that transports the design film 30 to the pressure roll pair 163. The design film transport device 160 includes a design film roll 161 and a plurality of transport rolls 162. The design film roll 161 is a roll around which the long design film 30 is wound. The transport roll 162 pulls out the design film 30 from the design film roll 161, and transports it to the pressure bonding roll pair 163. The pressure-bonding roll pair 163 pressure-bonds the design film 30 to the upper adhesive layer 42. Thereby, the designed metal plate 10 is manufactured. The cooling device 170 is, for example, a water cooling tank and cools the designed metal plate 10.

(3-2. Second example)
The second example of the manufacturing method is realized by using the manufacturing apparatus 101 shown in FIG. 4, for example. Therefore, the configuration of the manufacturing apparatus 101 will be described. Here, the manufacturing apparatus 101 has the same configuration as the manufacturing apparatus 100 described above, except that the installation positions of the second roll coater 140 and the second oven 150 are different. Therefore, differences from the manufacturing apparatus 100 will be described.

  The second roll coater 140 and the second oven 150 are provided in the design film transport device 160. The applicator roll 144 of the second roll coater 140 applies the upper layer side adhesive composition 141 to the design film 30 to form the upper layer side adhesive layer 42 on the design film 30.

  The second oven 150 heats the design film 30 to bring the upper-side adhesive layer 42 into close contact with the design film 30. Here, the heating temperature of the design film 30 is not particularly limited as long as it is a temperature at which the design film 30 is in close contact with the upper adhesive layer 42, that is, a temperature at which the upper adhesive develops an anchoring effect on the design film 30. For example, the heating temperature of the design film 30 may be 180 ° C. or lower.

  The pressure-bonding roll pair 163 pressure-bonds the upper adhesive layer 42 on the design film 30 to the lower adhesive layer 41 on the metal plate 20 while keeping the temperature of the metal plate 20 at 180 ° C. or lower. That is, the pressure bonding roll pair 163 manufactures the design metal plate 10 by bonding the lower adhesive layer 41 and the upper adhesive layer 42 together. As described above, since the softening temperature of the upper layer side adhesive is low, the upper layer side adhesive is sufficiently softened even if the temperature of the metal plate 20 is 180 ° C. or lower. Further, since the low-temperature upper adhesive layer 42 can be pressure-bonded to the design film 30, the heat conducted to the design film 30 can be reduced. Therefore, the deterioration of the design applied to the design film 30 can be suppressed.

  The temperature of the metal plate 20 can be further lowered according to the softening temperature of the upper adhesive. For example, when the softening temperature of the upper layer side adhesive is 70 ° C. or lower, the temperature of the metal plate 20 is preferably 165 ° C. or lower, and more preferably 140 ° C. or lower. When the softening temperature of the upper layer side adhesive is 70 ° C. or lower, the upper layer side adhesive is sufficiently softened even if the temperature of the metal plate 20 is within the above range. The lower limit of the heating temperature of the metal plate 20 may be the softening temperature of the upper layer adhesive -40 ° C. The method of setting the temperature of the metal plate 20 to 180 ° C. or lower is not particularly limited. For example, when the metal plate 20 is heated to more than 180 ° C. in the first oven 130, the temperature of the metal plate 20 can be set to 180 ° C. or lower by adjusting the distance between the first oven 130 and the pressure bonding roll pair 163. it can. That is, the temperature of the metal plate 20 may be 180 ° C. or lower due to the residual heat of the first oven 130. A cooling device similar to the cooling device 170 may be installed between the first oven 130 and the pressure roll pair 163. When the heating temperature of the metal plate 20 by the first oven 130 is 180 ° C. or lower, a separate oven may be installed between the first oven 130 and the pressure roll pair 163. This oven reheats the metal plate 20 to a temperature of 180 ° C. or lower. Further, the temperature of the metal plate 20 may be set to 180 ° C. or lower by the residual heat of the second oven 150, that is, the residual heat provided from the design film 30 on which the upper adhesive layer 42 is laminated.

  Here, the design film 30 in which the upper layer side adhesive layer 42 is laminated, that is, the laminated film is prepared in advance, and the upper layer side adhesive layer 42 of this laminated film is adhered to the lower layer side adhesive layer 41 on the metal plate 20. Good. Alternatively, the metal plate 20 on which the lower-side adhesive layer 41 is laminated, that is, the laminated metal plate is prepared in advance and brought into close contact with the prepared laminated film (or the laminated film produced by the manufacturing apparatus 101). Good.

  In the manufacturing apparatuses 100 and 101 according to the first example and the second example, the bonding interface when the design film 30 is pressure-bonded to the metal plate 20 is the upper layer side adhesive layer 42 / the design film 30, the upper layer side adhesive layer 42 / It becomes the lower layer side adhesive layer 41. Therefore, the manufacturing apparatuses 100 and 101 perform organic substance / organic substance bonding. Organic substances are easily deformed even when the heating temperature is 180 ° C. or lower, and a sufficient anchor effect is easily exhibited. Therefore, also in this respect, the design film 30 and the metal plate 20 can be firmly adhered to each other.

<1. Preparation of adhesive composition>
(1-1. Common process)
An adhesive composition was prepared by the following steps. First, 200 parts by mass of high-boiling naphtha (Solvesso 150) was placed in a flask equipped with a stirring rod and a reflux condenser and stirred for about 10 minutes. Then, 100 parts by mass of the adhesive main agent (any one of polyester, acrylic, and urethane) was added, and the mixture was stirred and dissolved at room temperature for 4 hours. Here, the adhesive main component constitutes the above-mentioned upper layer side adhesive or lower layer side adhesive. After confirming that the adhesive main agent was completely dissolved, 20 parts by mass of MEK (methyl ethyl ketone, manufactured by Maruzen Petroleum Co., Ltd.) was added and stirred at room temperature for 30 minutes. An adhesive composition was produced by the above steps.

(1-2. Preparation of curable adhesive composition)
A curable adhesive by blending a curing agent solution (either Y6410-B manufactured by Yokohama Rubber Co., or Desmodur RFE manufactured by Bayer Co., Ltd.) and a catalyst (U-CAT SA102 manufactured by San-Apro Co., Ltd.) with the adhesive composition A composition was obtained. Here, Y6410-B is a polyisocyanate resin having 30 mol% of isocyanate groups with respect to all dicarboxylic acid residues. Here, the amount of the curing agent solution added was 4 parts by mass in terms of solid content, and the amount of the catalyst added was 0.1 parts by weight in terms of solid content.

(1-3. Preparation of adhesive composition containing silane coupling agent and filler)
In a flask equipped with a stir bar and a reflux condenser, 200 parts by mass of high-boiling naphtha (Solvesso 150) and 2.5 parts by mass of fine silica (Aloezil R-972) as a filler were charged and stirred for about 10 minutes. Then, 100 parts by mass of the adhesive main agent (any one of polyester, acrylic, and urethane) was added, and the mixture was stirred and dissolved at room temperature for 4 hours. After confirming that the adhesive main agent was completely dissolved, a silane compound (KBM-402 manufactured by Shin-Etsu Chemical Co., Ltd.) as a silane coupling agent and a catalyst were added, and the mixture was stirred at room temperature for 1 hour. Finally, 20 parts by mass of MEK (methyl ethyl ketone, manufactured by Maruzen Petroleum Co., Ltd.) was added and stirred at room temperature for 30 minutes. An adhesive composition was obtained through the above steps. The composition of the adhesive composition is shown in Tables 1-3.

  The numerical values in Tables 1 to 3 mean parts by mass except for the softening temperature. Moreover, the mass part of a hardening | curing agent solution and a catalyst means the mass part of solid content. Further, Table 4 shows the specific contents of the materials constituting each adhesive composition.

<2. Measurement of softening temperature>
The softening temperature of each adhesive composition, specifically, the softening temperature of the adhesive main component constituting the adhesive composition was measured by the following method. First, the adhesive composition was gently poured into a PE (polyethylene) container having a diameter of 7.5 cm and a thickness of about 1 cm. Then, the container was gently tilted to make the thickness of the adhesive composition uniform in the container. Then, the container was kept horizontal and dried in a thermostatic chamber at 20 ° C. for 1 to 3 days to prepare an adhesive film. Then, the adhesive film was gently peeled from the container. The softening temperature was measured using the adhesive composition before adding the curing agent and the catalyst as the adhesive composition.

  Then, the softening temperature was measured using a thermomechanical analyzer. Specifically, while heating the adhesive film at 2 ° C./minute, a cylindrical needle having a diameter of 1 mm was pushed into the sample with a load of 500 mN. Then, the temperature when the penetration depth of the cylindrical needle into the adhesive film satisfies the above mathematical expression (1) was defined as the softening temperature. The softening temperature of each adhesive composition is summarized in Tables 1 to 3.

<3. Design film production>
A design film was prepared or manufactured by the following steps.
(3-1. Vinyl chloride film)
(3-1-1. Single color embossed film)
LE301 manufactured by Okamoto was prepared as a monochromatic embossed film made of vinyl chloride. The film thickness is 150 μm. The surface of the embossed film is provided with a Kawashima embossed pattern having a depth of 15 μm.

(3-1-2. High-definition movie film)
The resin composition used in the production of the monochromatic film was formed into a film by a calendering method to produce a 120-μm-thick original fabric film. Here, a mirror-finished raw film was produced by using a mirror-finished roll as the roll used in the calendar method. Then, using a continuous laminator, a polyester adhesive (S-580X manufactured by Sekisui Fuller Co., Ltd.) was applied to the original film and dried at 80 ° C. After drying, a 25 μm-thick biaxially stretched PET (polyethylene terephthalate) film having a grain print on the adhesive-coated surface of the original film was laminated so that the printed surface and the adhesive were in contact with each other. A high-definition image film was obtained through the above steps.

(3-2. Polyester film)
A two-layer T die was used to obtain a monochromatic film made of a PET alloy containing a white pigment (20% by mass) and a raw film. The thickness of each film was 100 μm. It should be noted that an embossing roll is used for the monochromatic film, and the above 3-1-1. The same embossing pattern was applied to obtain a monochromatic embossing film. Further, the original film was mirror-finished by using a mirror-finished roll. Furthermore, the above-mentioned 3-1-2. By performing the same doubling step as above, a 25 μm-thick biaxially stretched PET film having a grain print was laminated on the original film. A high-definition image film was obtained by this process. Here, the PET-based alloy means PET (MA1344 manufactured by Unitika), polyolefin-based elastomer (manufactured by Mitsui Chemicals, Tuffmer 4085S), and ethylene terpolymer (Sumitomo Chemical Co., Ltd., Bondfast 7L) 87/10 / It is an alloy mixed with 3.

(3-3. Polyolefin film)
Using a two-layer T die, a two-layer PP film (upper layer: PP (polypropylene, manufactured by Nippon Polypro Co., Novarex FB3B)), lower layer: maleic anhydride modified PP (manufactured by Mitsui Chemicals, Admer SF725) (upper layer / Lower layer = 90/10 μm) was prepared. A monochromatic embossed film and a mirror-finished polyolefin raw fabric were obtained using this two-layer PP film. Here, the above-mentioned 3-1-1. The same embossed pattern was added. Furthermore, the above-mentioned 3-1-2. By performing the same doubling step as above, a 25 μm-thick biaxially stretched PET film having a grain print was laminated on the original film. A high-definition image film was obtained by this process.

(3-4. Other films)
As the fluororesin film and the acrylic resin film, a 40 μm thick PVD film (Tedlar, manufactured by DuPont) and PMMA (100 μm thick, manufactured by Kyowa Leather Co., Ltd.) were prepared. The above 3-1-1. A single-color embossed film was produced by applying the same embossed pattern as described above.

  When the softening temperature of each of the above design films was measured, it was confirmed that each was less than 150 ° C. Specifically, the softening temperature of the vinyl chloride film is 140 ° C, the softening temperature of the polyester film is 135 ° C, the softening temperature of the polyolefin film is 90 ° C, the softening temperature of the PVD film is 80 ° C, and the softening temperature of the PMMA film is 140 ° C. Met.

<4. Metal plate>
As a metal plate, two kinds of 0.45-mm-thick zinc-based gold steel plates (Nippon Steel & Sumitomo Metal super dimer (K08) (hereinafter, also referred to as "SD steel plate"), GI steel plate (Z18)), Al plate (A5052, 1) 0.2 mm thick) was prepared. Then, after subjecting these metal plates to alkali degreasing treatment, a chromate solution was applied to form a chromate film of about 45 mg / m ^{2 on} the metal plate surface. Further, as other metal plates, a roughened Cu plate (70 μm, electrolytic copper foil plate) and a JIS H4600 standard Ti plate (1 mm thick) subjected to vacuum annealing and pickling finish were prepared.

<5. Fabrication of Designed Metal Plate>
(5-1. Examples 1-37)
The design metal plates according to Examples 1 to 37 were manufactured by the following steps. First, a metal plate was coated with a lower layer adhesive composition (lower layer side adhesive layer composition) by a coater so that the thickness was 2 μm. Then, the metal plate was heated to the lower layer heating temperature (detailed values are shown in the table described later). Thereby, the lower adhesive layer was formed on the metal plate. After cooling the metal plate to room temperature, the adhesive composition for the upper layer (upper layer side adhesive composition) was applied on the lower layer side adhesive layer so as to have a thickness of 2 μm. Then, the metal plate was heated to the upper layer heating temperature (detailed values are shown in the table described later) to form the upper layer side adhesive layer. After the temperature of the metal plate reached the upper layer heating temperature, the above-mentioned vinyl chloride film (either a monochromatic embossed film or a high-definition film) was pressure-bonded to the surface of the upper adhesive layer. A design metal plate was obtained through the above steps. The heating temperature of the metal plate was measured using a thermocouple previously mounted on the surface of the metal plate. In Examples 1 to 11, a polyester-based adhesive composition was used as the adhesive composition for the upper layer and the adhesive composition for the lower layer. In Examples 12 to 18, an acrylic adhesive composition was used as the adhesive composition for the upper layer and the adhesive composition for the lower layer. In Examples 19 to 37, adhesive compositions having different material systems were used as the adhesive composition for the upper layer and the adhesive composition for the lower layer. The metal plate used was different for each example. In the following description, the design metal plate to which the monochromatic embossing film is attached is also referred to as “monochromatic embossing plate”, and the design metal plate to which the high-definition image film is attached is also referred to as “high-definition image plate”.

(5-2. Examples 38 to 41)
A design metal plate was produced by performing the same steps as in Example 1 except that the type of the design film was changed.

(5-3. Example 42)
The design metal plate according to Example 42 was manufactured through the following steps. First, an adhesive composition for the lower layer was applied to a metal plate with a coater so that the thickness was 2 μm. Then, the metal plate was heated to the lower layer heating temperature. Thereby, the lower adhesive layer was formed on the metal plate. Then, the metal plate was cooled to room temperature. On the other hand, the adhesive composition for the upper layer was applied onto the above-mentioned vinyl chloride film with a coater so that the thickness was 2 μm. Then, the design film was heated to the upper layer heating temperature. Thereby, the upper adhesive layer was formed on the vinyl chloride film. Then, the design film was cooled to room temperature. Then, the metal plate on which the lower adhesive layer was formed was heated to the upper layer heating temperature, and the upper adhesive layer on the design film was pressure-bonded to the lower adhesive layer on the metal plate. A design metal plate was obtained through the above steps.

(5-4. Comparative Examples 1 to 13)
A design metal plate was produced by the same steps as in Example 1 except that the adhesive layer was composed of only one layer. That is, the adhesive layer was formed on the metal plate by the same steps as in Example 1. Then, the metal plate was heated to a heating temperature (detailed values are shown in the table described later). Then, the vinyl chloride film was pressure-bonded to the adhesive layer. A design metal plate was produced by the above steps.

(5-5. Comparative Examples 14 to 17)
A design metal plate was produced by the same steps as in Example 1 except that the softening temperature of the upper layer side adhesive was higher than the softening temperature of the lower layer side adhesive.

(5-6. Comparative Example 18)
A design metal plate was produced by the same steps as in Example 1 except that the softening temperature of the lower layer side adhesive was set to less than 90 ° C.

(5-7. Comparative Example 19)
A design metal plate was produced by the same steps as in Example 1 except that the softening temperature of the upper layer side adhesive was higher than 80 ° C.

(5-8. Comparative Examples 20 to 27)
A design metal plate was produced by performing the same steps as in Comparative Example 1 except that the type of the design film was changed. Tables 5 to 15 collectively show the configurations of the designed metal plates produced in the respective examples and comparative examples.

<6. Evaluation of designed metal sheets>
(6-1. Initial adhesion)
Initial adhesion was evaluated using a single color embossed plate. Specifically, a # -type notch having a width of 5 mm was made in the monochromatic embossed film with a cutter knife. Here, the depth of the cut is set to a depth that reaches the metal plate. Then, the # type notch portion was overhanged by 8 mm using an Erichsen tester (DKSH, Erichsen tester). Here, the center of the overhanging portion (top portion) was made to coincide with the center of the # -type notch portion. Then, the # -type notched portion was forcibly peeled with tweezers, and the degree of peeling was evaluated according to the following criteria.
⊚: Rating of 5 (film almost never peels due to cohesive failure)
⊚: Rating 4 (peeling off only the top part)
◯: Score 3 (the whole top part and less than 1/3 of the side part are peeled off)
X: Rating 2 (the entire top portion and the entire side surface are peeled off)
XX: Rating 1 (Peeling around the entire top portion, the entire side surface processing portion, and the # -type cut portion)
Then, the same test was repeated 5 times. The results are summarized in Tables 5 to 15. In addition, when there is a variation in the evaluation for each test, the upper and lower limits of the evaluation are shown in the table.

(6-2. Emboss return rate)
Using a single-color embossed plate, the emboss return rate, which is one of the evaluation indices of the initial design retention, was evaluated. Specifically, the arithmetic mean roughness Ra1 of the surface of the single-color embossed film and the arithmetic average roughness Ra2 of the surface of the single-color embossed plate (specifically, the surface of the single-color embossed film attached to the single-color embossed plate) are contact-type. It was measured with a two-dimensional roughness meter (OLS400 manufactured by Olympus Corporation). The observation surface was 20 × 20 mm. Then, the emboss return rate, which is one of the indexes of the initial design retention, was calculated by the following mathematical expression (2).
Emboss return rate χ: χ = 1-Ra2 / Ra1 (2)

(6-3. Vividness and discoloration)
A high-definition image film was used to evaluate the image clarity (PDG value) and discoloration, which are one of the evaluation indices of the initial design retention. Specifically, the sharpness of the high-definition image film surface and the high-definition image plate surface (specifically, the surface of the high-definition image film attached to the surface of the high-definition image plate) is measured by a sharpness gloss meter. (The PGD-IV manufactured by Japan Color Research Institute) was used for measurement. Then, the sharpness was evaluated according to the following criteria.
⊚: The difference in sharpness between the high-definition film and the high-definition projection plate is less than 0.1. ○: The difference in the sharpness between the high-definition projection film and the high-definition projection plate is 0.1 to 0.2.
X: The difference in the sharpness of the high-definition image film and the high-definition image plate is 0.3 or more. And, the same test was repeated 5 times. The results are summarized in Tables 5 to 15. In addition, when there is a variation in the evaluation for each test, the upper and lower limits of the evaluation are shown in the table.

Furthermore, the a value of the high-definition image film surface and the high-definition image plate surface was measured with a color difference meter (CM-2600d manufactured by Konica Minolta). Here, the a value is a value for evaluating redness. Since redness tends to disappear particularly during the production of the designed metal plate, the a value was used to evaluate the color fading. Then, a difference in a value Δa (= a value of high-definition image film-a value of high-definition image plate) was calculated, and color fading was evaluated according to the following criteria.
⊚: △ a <3.0
○: 3.0 <△ a <5.0
X: △ a> 5.0
Then, the same test was repeated 5 times. The results are summarized in Tables 5 to 15. In addition, when there is a variation in the evaluation for each test, the upper and lower limits of the evaluation are shown in the table.

(6-4. Durability)
Durability was evaluated using a single color embossed plate. Specifically, the single-color embossed plate was immersed in boiling water and hot water at 75 ° C. for 20 days. In addition, when the softening temperature of the lower layer side adhesive was less than 100 ° C., it was immersed only in hot water at 70 ° C. except for Example 6. Hereinafter, such a test is also referred to as "immersion test". Then, the film adhesion after the immersion test was evaluated by the same test as the above-mentioned initial adhesion. Furthermore, the edge of the single-color embossed plate after the immersion test was visually observed to evaluate whether the single-color embossed film returned (peeled) and whether it corroded. It should be noted that the presence or absence of corrosion was determined only for metal plates in which corrosion is a problem, that is, GI steel plate and SD steel plate. Then, the same test was repeated 5 times. The results are summarized in Tables 5 to 15. In addition, when there is a variation in the evaluation for each test, the upper and lower limits of the evaluation are shown in the table.

<7. Consideration of evaluation results>
In Examples 1 to 43, the initial adhesion, the initial design retention, and the durability were all highly evaluated. In Examples 1 to 43, since the softening temperature of the upper layer side adhesive is 80 ° C. or lower, even if the upper layer heating temperature is low (specifically, even if it is 180 ° C. or lower), the design film is sufficient. It can be closely attached to a metal plate. Therefore, both the initial adhesive force and the initial design holding property are improved. Further, since the softening temperature of the lower layer side adhesive is 90 ° C. or higher, even if the design metal plate is exposed to a high temperature and high humidity environment for a long time, water molecules at the interface of the metal plate / lower layer side adhesive layer Intrusion can be prevented. Therefore, the durability is increased.

  Further, in Example 1, the softening temperature of the upper layer side adhesive is higher than 70 ° C, but in Examples 2 to 11, the softening temperature of the upper layer side adhesive is 70 ° C or lower. The initial design retention of Examples 2 to 11 was superior to the initial design retention of Example 1. In Examples 2 to 11, the softening temperature of the upper layer side adhesive is 70 ° C. or lower, so that the upper layer heating temperature can be lower than that of Example 1 (specifically, 165 ° C. or lower). As a result, excellent initial design retention was obtained. In addition, according to Examples 4 and 6, it was found that the initial design holding property was further improved by setting the upper layer heating temperature to 140 ° C. or lower.

  Furthermore, when the softening temperature of the lower layer side adhesive was 100 ° C. or higher, it was possible to maintain a strong adhesive force including the edges even under extremely severe high temperature and high humidity such as immersion in boiling water. That is, extremely high durability could be obtained.

  Further, it was found that the above effect can be more remarkably obtained when the difference between the softening temperature of the lower layer side adhesive and the softening temperature of the upper layer side adhesive is 30 ° C. or more.

  Furthermore, when comparing Example 7 with Examples 1 to 6, in Example 7, the durability was higher. Similarly, when comparing Example 16 with Examples 12 to 15, in Example 16, the durability was higher. In Examples 7 and 16, the silane coupling agent was added to the lower layer side adhesive composition in an amount of 2 to 15 parts by mass based on 100 parts by mass of the lower layer side adhesive. Therefore, in Examples 7 and 16, the adhesion between the metal plate and the lower adhesive layer is further enhanced. Therefore, even under extremely severe high temperature and high humidity, it was possible to maintain a strong adhesive force including the end portion.

  On the other hand, in Comparative Examples 1 to 4, 7 to 10 and 12 to 13, the adhesive layer is a single layer and the softening temperature of the adhesive is 80 ° C. or lower. Therefore, even if the heating temperature was low (180 ° C. or lower), the design film could be sufficiently adhered to the metal plate. However, the adhesion was significantly reduced after the immersion test. The reason for this is that the softening temperature of the adhesive is low. That is, since the softening temperature of the adhesive is low, it is considered that water molecules penetrated from the end of the designed metal plate to the interface between the metal plate and the lower adhesive layer during the immersion test, and the water molecules reduced the adhesion. . Therefore, in Comparative Examples 1 to 4, 7 to 10 and 12 to 13, other durability tests were not performed. Further, when the design film can be adhered to the metal plate at a low temperature, the initial design holding property is also increased, and therefore, the test concerning the initial design holding property was not conducted.

  Moreover, in Comparative Examples 5, 6, and 11, the adhesive layer is a single layer, and the softening temperature of the adhesive is 90 ° C. or higher. For this reason, when the heating temperature was set to 180 ° C. or lower, the design film and the metal plate could not be sufficiently adhered. In the specific example, the initial adhesion was significantly reduced. On the other hand, when the heating temperature was higher than 180 ° C., the design film and the metal plate could be sufficiently adhered. However, since the design film is exposed to a high temperature, the initial design holding property is significantly reduced. The same results as in Comparative Examples 1 to 13 were obtained in Comparative Examples 20 to 27 in which the types of the design films were different. In addition, when the design film was an acrylic film, the durability was particularly deteriorated. It is considered that the acrylic film easily penetrates water molecules.

  Further, in Comparative Examples 14 to 17, the softening temperature of the upper layer-side adhesive is 90 ° C. or higher, so the design film is sufficiently adhered to the metal plate unless the upper layer heating temperature is set higher (greater than 180 ° C.). I couldn't. As a result, the initial design retainability was significantly reduced. Furthermore, the immersion test caused corrosion at the edges of the designed metal plate. Since the softening temperature of the lower layer side adhesive is 80 ° C. or less, water molecules intrude into the interface of the metal plate / lower layer side adhesive layer from the end of the design metal plate during the immersion test, and the water molecules cause the metal plate to Probably corroded. In Comparative Examples 14 to 17, the film peeling was not evaluated because corrosion occurred at the edges.

  Moreover, in Comparative Example 18, the softening temperature of the lower layer side adhesive is higher than the softening temperature of the upper layer side adhesive, and the softening temperature of the upper layer side adhesive is 80 ° C. or lower. Therefore, even if the heating temperature was low (180 ° C. or lower), the design film could be sufficiently adhered to the metal plate. However, the softening temperature of the lower layer side adhesive is less than 90 ° C. Then, the immersion test markedly reduced the adhesion. Since the softening temperature of the lower layer side adhesive is less than 90 ° C., it is considered that water molecules penetrated into the interface of the metal plate / lower layer side adhesive layer during the immersion test, and the water molecules reduced the adhesion.

  In Comparative Example 19, the softening temperature of the lower layer side adhesive is higher than the softening temperature of the upper layer side adhesive. However, since the softening temperature of the upper layer-side adhesive is higher than 80 ° C., the design film could not be sufficiently adhered to the metal plate unless the upper layer heating temperature was set higher (greater than 180 ° C.). As a result, the initial design retainability was significantly reduced.

  Although the preferred embodiments of the present invention have been described above in detail with reference to the accompanying drawings, the present invention is not limited to such examples. It is obvious that a person having ordinary knowledge in the field of the technology to which the present invention pertains can come up with various changes or modifications within the scope of the technical idea described in the claims. Of course, it is understood that these also belong to the technical scope of the present invention.

10 Design Metal Plate 20 Steel Plate 30 Design Film 40 Adhesive Layer 41 Lower Adhesion Layer 42 Upper Adhesion Layer 100, 101 Manufacturing Device for Design Metal Plate 120 First Roll Coater 130 First Oven 140 Second Roll Coater 150 Second Oven 160 Design film transport device 170 Cooling device

Claims (8)

Among the multilayer adhesives for a design metal plate for adhering a metal plate and a design film, an upper layer side adhesive layer composition constituting an upper layer side adhesive layer in contact with the design film,
The composition for an upper layer side adhesive layer, wherein the composition for the upper layer side adhesive layer contains an upper layer side adhesive having a softening temperature of 80 ° C. or lower.   The composition for the upper adhesive layer according to claim 1, wherein the softening temperature of the upper adhesive is 70 ° C. or lower.   3. The upper layer side adhesive is composed of any one or more of polyester, acrylic, urethane, epoxy, and urea thermosetting adhesives. The composition for the adhesive layer on the upper layer side according to 1.   The upper layer side adhesive is a polyester thermosetting adhesive obtained by adding 3 to 25 parts by mass of a polyisocyanate resin having an isocyanate group of 30 mol% or more to all dicarboxylic acid residues to 100 parts by mass of a linear polyester resin. It exists, The composition for upper side adhesive layers of any one of Claims 1-3 characterized by the above-mentioned. Of the multilayer adhesive for a design metal plate for bonding a metal plate and a design film, a lower layer side adhesive layer composition constituting a lower layer side adhesive layer in contact with the metal plate,
The composition for the lower adhesive layer comprises a lower adhesive having a softening temperature of 90 ° C. or higher.   The composition for the lower adhesive layer according to claim 5, wherein the softening temperature of the lower adhesive is 100 ° C or higher.   7. The lower layer side adhesive is made of any one or more of a polyester type, an acrylic type, a urethane type, an epoxy type, and a urea type thermosetting adhesive. The composition for the lower layer side adhesive layer according to [4].   The lower layer side adhesive is a polyester thermosetting adhesive obtained by adding 3 to 25 parts by mass of a polyisocyanate resin having an isocyanate group of 30 mol% or more to all dicarboxylic acid residues to 100 parts by mass of a linear polyester resin. It exists, The composition for the lower side adhesive layer of any one of Claims 5-7.

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