JP6647081B2 - Decorative metal plate and method of manufacturing the same - Google Patents

Description

  The present invention relates to a design metal plate and a method for manufacturing the same.

  In recent years, it has been designed for interior and exterior of various buildings (for example, interior and exterior walls of houses, roofs, partitions, etc.), furniture parts, housing of home appliances, truck bodywork, vehicle interior and exterior, ship interior and exterior, road protection walls, etc. The use of steel sheets is increasing. Of these uses, the design steel sheet is often applied to the interior and exterior of a house, and is particularly often applied to the wall of a bathroom in a house.

  Here, the design steel sheet is obtained by laminating a design film on a steel sheet. The design film is a film provided with various designs (for example, colors, patterns, embosses, etc.). A design steel sheet is roughly produced by the following steps. That is, first, an adhesive layer is formed on a steel plate or a design film by laminating (for example, applying) an adhesive on a steel plate or a design film. Here, the adhesive may be laminated on a steel plate or a design film in a state of being dissolved or dispersed in the solvent. Next, the adhesive layer is heated to soften the adhesive. When a solvent is contained in the adhesive layer, the solvent evaporates by heating. Next, the steel plate and the design film are pressed. The design steel sheet is manufactured by the above steps.

  Patent Literatures 1 to 6 disclose a design steel sheet in which the adhesive layer is a single layer. Patent Document 1 discloses a polyester-based adhesive in which a polyisocyanate-based curing agent is blended with a urethane-modified polyester base material having a defined molecular weight and terminal functional group content so that the NCO / OH ratio falls within a predetermined range. . In Patent Literature 1, an adhesive layer composed of a single layer is formed on a steel plate using this adhesive. Then, the design film and the steel plate are pressed.

  According to the technique disclosed in Patent Literature 1, by regulating the molecular weight of the main agent, the wettability to the design film and the strength of the adhesive itself are maintained. Further, by defining the terminal functional group, the adhesion between the steel sheet and the design film is ensured. Then, the cohesive force and the 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.

  Patent Document 2 discloses an acrylic adhesive obtained by crosslinking an acrylic polymer bonded to an epoxy resin with an amine compound. In Patent Document 2, an adhesive layer composed of a single layer is formed on a steel plate using this adhesive. The adhesive disclosed in Patent Document 2 also softens at a low temperature. 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.

  Patent Document 3 discloses a polyester-based adhesive using a polyisocyanate to which a silane coupling agent is added as a curing agent. In Patent Document 3, an adhesive layer composed of a single layer is formed on a steel plate 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, a single-layer adhesive 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 a design film is pressure-bonded to a steel plate 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 Literatures 7 and 8 disclose a design steel sheet having two adhesive layers. In Patent Document 7, the lower adhesive layer (that is, the steel plate side) contains an adhesive mainly composed of a polar group-containing modified polyethylene resin, and the upper adhesive layer (that is, the design film side) contains a polar group-containing modified polyethylene resin. Includes an adhesive mainly composed of polypropylene resin. An adhesive containing a polar group-containing modified polypropylene resin as a main component is an adhesive that softens at a high temperature, and an adhesive containing a polar group-containing modified polyethylene resin as a main component is an adhesive that softens at a low temperature.

  In Patent Document 7, a design steel sheet is manufactured by the following steps. That is, a plurality of adhesive layers are formed on a design film using a multilayer extruder. Then, the design film on which these adhesive layers are formed is pressure-bonded to a steel plate that has been heated in advance. Thereafter, by heating the design film and the steel sheet, the adhesive on the lower layer side is softened, and the design film is brought into close contact with the steel sheet. The design steel sheet is manufactured by the above steps. Here, since the lower adhesive is composed of an adhesive that softens at a low temperature, even if the heating temperature for softening the lower adhesive is a low temperature, the design film is sufficiently adhered to the steel sheet. be able to.

  In Patent Document 8, the lower adhesive layer includes a urethane-based adhesive having a glass transition temperature of −65 to −10 ° C., and the upper adhesive layer includes a polyester-based adhesive having a glass transition temperature of 20 to 90 ° C. . The urethane-based adhesive softens at low temperatures because of its low glass transition temperature. The above-mentioned polyester-based adhesive softens at a high temperature because of its high glass transition temperature. In Patent Document 8, a design steel sheet is manufactured by the following steps. That is, the lower adhesive layer is formed on the steel sheet by laminating and heating the emulsion containing the urethane-based adhesive on the steel sheet. Then, an emulsion containing a polyester-based adhesive is laminated on the lower adhesive layer and heated to form an upper adhesive layer on the lower adhesive layer. Next, a design film is laminated on the upper adhesive layer. Here, since the lower adhesive layer is made of an adhesive that softens at a low temperature, even when the heating temperature for softening the lower adhesive is a low temperature, the design film is sufficiently adhered to the steel sheet. Can be.

JP-A-5-140340 JP-A-56-90874 Japanese Patent Publication No. 6-78517 JP 2010-6020 A JP 2005-219504 A JP-A-10-235782 JP-A-64-82931 JP 2008-279687 A

  By the way, from the viewpoint of stabilizing the quality of the design 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 strength of the adhesive during the production of the design steel sheet (such adhesive strength is also referred to as the primary adhesive strength) is developed at a temperature as low as possible. If the heating temperature for softening the adhesive is too high, the design given to the design film is deteriorated (that is, the quality of the design steel plate is reduced). Specifically, a large amount of heat is conducted to the design film in contact with the high-temperature adhesive, and the heat volatilizes the pigment in the design film. Further, 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 be sophisticated, so stabilizing the quality of the design 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, so that the productivity (production rate) of the design steel sheet is improved. In the design steel sheets disclosed in Patent Literatures 1, 2, 7, and 8, the heating temperature for softening the adhesive can be reduced, so that the deterioration of the design during the production of the design steel sheet can be suppressed.

  On the other hand, as described above, the design steel plate is particularly often applied to a wall of a residential bathroom. Residential bathrooms are extremely harsh environments with high temperature and high humidity, but the design steel plate maintains the adhesion between the design film and the steel plate for a long time (for example, 5 years or more) even in such a severe environment. It was required to be able to do it. That is, the adhesive strength of the adhesive after the design steel sheet is manufactured (such an adhesive strength is also referred to as a secondary adhesive strength) is that when the design steel sheet is used for a long time in a high-temperature and high-humidity environment. Was also required to be maintained at a high value.

  The present inventors have verified whether or not the designed steel plates disclosed in Patent Documents 1, 2, 7, and 8 can be adapted to a high-temperature and high-humidity environment. Specifically, the designed steel plates disclosed in Patent Documents 1, 2, 7, and 8 were produced, and an acceleration test was performed using these designed steel plates. Here, the accelerated test involves immersing the design steel plate 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 adapted to a high-temperature and high-humidity environment.

  In the above-described accelerated test, factors of "high temperature" and "water" act on the design steel plate. For this reason, in the above-described accelerated test, it is not known which factor causes the decrease in the adhesion. Therefore, the present inventors performed the following accelerated test in order to individually verify these factors. Specifically, the present inventor performed an acceleration test in which a design steel sheet was heated to 100 ° C. in a vacuum as an acceleration test for high temperatures. As a result, no change in adhesion was observed before and after the acceleration test. Then, the present inventor performed an accelerated test in which the design steel plate was immersed in water at 40 ° C. for 2 hours as an accelerated test for water. As a result, no change in adhesion was observed before and after the acceleration test. Therefore, the present inventor conducted an accelerated test in which the design steel plate 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 decreased significantly before and after the acceleration test. Specifically, the adhesive layer was easily separated at the interface with the steel sheet. As a result of the above, the present inventors have found that “water” and “high temperature” are causes of a decrease in adhesion.

  Furthermore, the inventor made 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 in which the design steel sheet was immersed in boiling water for 2 hours). As a result, almost no change in the adhesion was observed before and after the acceleration test. Therefore, the design steel sheets disclosed in Patent Documents 3 to 6 can be adapted to a high-temperature and high-humidity environment.

  And in the design steel plate disclosed by patent documents 1, 2, 7, and 8, the adhesive which contacts a steel plate softens at low temperature. On the other hand, in the design steel plates disclosed in Patent Literatures 3 to 6, the adhesive contacting the steel plate softens at a high temperature. Therefore, if the adhesive contacting the steel sheet softens at low temperature, the design steel sheet cannot be adapted to the high temperature and high humidity environment, but if the adhesive contacting the steel sheet softens at high temperature, the design steel sheet will not fit in the high temperature and high humidity environment. Will be able to adapt. The present inventor believes that this is due to the difference in the degree of softening of the two adhesives.

  The graphs L1 and L2 shown in FIG. 1 are graphs showing the correspondence between the temperature of the different adhesives and the degree of softening. 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, “adhesive A”). Agent B ") is one type of adhesive that softens at high temperatures. In addition, the degree of softening is measured by a thermomechanical analysis device (Thermal Mechanical Analysis). Specifically, the degree of softening can be 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./min, by the penetration depth at 200 ° C. It is a value obtained by The penetration depth of the cylindrical needle into the sample is measured according to JIS-K-7196. The vertical axis in FIG. 1 is given a negative sign for the degree of softening for easy understanding.

  The degree of softening 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, an increase in the softening degree of the adhesive means an increase in the free volume of the adhesive. Then, as the free volume of the adhesive increases, the 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 enter 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.

  The adhesives disclosed in Patent Literatures 1 and 2 soften at a low temperature, and thus have the same characteristics as the adhesive A. Therefore, when the design steel plate disclosed in Patent Documents 1 and 2 is exposed to a high-temperature and high-humidity environment, a large amount of water molecules enter the adhesive layer. Then, it is considered that these water molecules cut 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, the bond is hydrolyzed by water molecules penetrating into the adhesive layer. In addition, since the adhesive layer is plasticized and embrittled by water molecules, this is also considered to be a cause of the decrease in adhesion. For these reasons, when the design steel sheets disclosed in Patent Documents 1 and 2 are exposed to a high-temperature and high-humidity environment, it is considered that the adhesive layer is easily peeled off at the interface with the steel sheet. That is, it is considered that the secondary adhesion cannot be maintained in a high-temperature and high-humidity environment. On the other hand, the adhesives disclosed in Patent Documents 3 to 6 soften at a high temperature, and thus have the same properties 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, penetration of water molecules into the adhesive layer can be suppressed. Therefore, it is considered that the secondary adhesion is maintained even in a high-temperature and high-humidity environment.

  On the other hand, in the design steel sheets disclosed in Patent Documents 7 and 8, the adhesive constituting the lower adhesive layer has the same characteristics as the adhesive A, and the adhesive constituting the upper adhesive layer is an adhesive. It has the same characteristics as B. Thus, the upper adhesive layer functions as a barrier layer for water molecules. Therefore, penetration 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 face of the design steel sheet, a large amount of water molecules enter from this portion. Then, the water molecules that have entered the lower adhesive layer break the chemical bonds formed at the steel sheet / adhesive layer interface. Therefore, the design steel sheets disclosed in Patent Literatures 7 and 8 cannot maintain the secondary adhesion in a high-temperature and high-humidity environment.

  Thus, the design steel sheets disclosed in Patent Literatures 3 to 6 can maintain the secondary adhesion even in a high-temperature and high-humidity environment. However, in order to express primary adhesion, it was necessary to heat the adhesive layer to a high temperature during the production of the design steel sheet. For this reason, there was a possibility that the design applied to the design film during the production of the design steel sheet was 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 sheet, and to maintain the adhesion between the design film and the steel sheet even in a harsh environment of high temperature and high humidity. A possible design steel sheet was not proposed.

  Further, in recent years, from the viewpoint of, for example, reducing the manufacturing cost of the design steel sheet, a demand for making the design film as thin as possible has become very strong. However, when the design film is simply made thinner, there is a problem that the concealing property is reduced. That is, when the design film has a certain thickness, the steel plate on the back side of the design film is concealed by the design film. However, when the design film is thinned, there is a possibility that the design film cannot sufficiently cover the steel sheet. Further, when the thin design film is attached to a steel plate, the heat of the adhesive layer is easily conducted to the entire design film. For this reason, there is also a problem that the design applied to the design film is very likely to deteriorate.

  Therefore, the present invention has been made in view of the above-described problems, and an object of the present invention is to suppress the deterioration of a design applied to a design film at the time of manufacturing a design metal plate, and to prevent high temperature and high temperature. New and improved that can maintain the adhesion between the design film and the metal plate even in a harsh environment of high humidity, and can maintain the concealing property even when the design film is thinned. An object of the present invention is to provide a design metal plate and a method for manufacturing the same.

  In order to solve the above problems, according to one aspect of the present invention, a metal plate, a lower adhesive layer laminated on the metal plate, an upper adhesive layer laminated on the lower adhesive layer, A design film laminated on the side adhesive layer, wherein the lower layer adhesive layer includes a lower layer adhesive and an inorganic pigment, the upper layer adhesive layer includes an upper layer adhesive, and the upper layer adhesive is softened. The temperature is 80 ° C. or lower, the softening temperature of the lower adhesive is 90 ° C. or higher, and the lower adhesive layer contains 3 to 50 parts by mass of the inorganic pigment based on 100 parts by mass of the lower adhesive. The design metal plate is provided.

  Here, the lower adhesive layer may contain 25 to 50 parts by mass containing an inorganic pigment with respect to 100 parts by mass of the lower adhesive.

  Further, the average particle size of the inorganic pigment may be 1 μm or less.

  Further, the average particle size of the inorganic pigment may be 0.2 to 0.4 μm.

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

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

  Further, the lower-layer adhesive and the upper-layer adhesive may be composed of at least one of polyester-based, acrylic-based, urethane-based, epoxy-based, and urea-based thermosetting adhesives.

  Further, the lower layer adhesive and the upper layer adhesive are a polyester resin obtained by adding 3 to 25 parts by mass of a polyisocyanate resin having an isocyanate group of 30 mol% or more based on all dicarboxylic acid residues to 100 parts by mass of a linear polyester resin. It may be a thermosetting adhesive.

  In addition, the lower adhesive layer may contain 2 to 15 parts by mass of the silane coupling agent with respect to 100 parts by mass of the lower adhesive.

  Further, the design film may be composed of any one or more of a vinyl chloride resin, a polyester resin, an acrylic resin, a polyolefin resin, and a fluororesin.

  Further, the design film may be made of a vinyl chloride resin.

  In addition, the softening temperature of a portion of the design film that is in contact with the upper adhesive layer may be lower than 150 ° C.

  According to another aspect of the present invention, there is provided a method for manufacturing a design metal plate for manufacturing the design metal plate, wherein the metal plate at 180 ° C. or lower and the design film are interposed via a lower adhesive layer and an upper adhesive layer. The present invention provides a method for manufacturing a design metal plate, characterized in that the metal plate is adhered.

  According to another aspect of the present invention, the step of forming the lower adhesive layer on the metal plate by laminating the lower adhesive and the inorganic pigment on the metal plate, and heating the metal plate, the lower layer A step of adhering the side adhesive layer to the metal plate; a step of forming the upper layer adhesive layer on the lower layer adhesive layer by laminating the upper layer adhesive on the lower layer adhesive layer; By heating to the heating temperature of, the step of softening the upper layer adhesive, and the step of laminating the design film on the upper layer adhesive layer, the softening temperature of the upper layer adhesive is 80 ℃ or less, The softening temperature of the lower adhesive is 90 ° C. or more, and the lower adhesive layer contains 3 to 50 parts by mass of an inorganic pigment with respect to 100 parts by mass of the lower adhesive. A method is provided.

  According to another aspect of the present invention, the step of forming the lower adhesive layer on the metal plate by laminating the lower adhesive and the inorganic pigment on the metal plate, and heating the metal plate, the lower layer A step of bringing the side adhesive layer into close contact with the metal plate, a step of preparing a laminated film in which the upper layer adhesive layer containing the upper layer adhesive is laminated on the design film, and setting the temperature of the metal plate to 180 ° C. or lower. Bonding the lower adhesive layer on the metal plate and the upper adhesive layer on the design film, wherein the softening temperature of the upper adhesive is 80 ° C. or less, and the softening temperature of the lower adhesive is 90 ° C. or higher, and the lower adhesive layer contains 3 to 50 parts by mass of an inorganic pigment based on 100 parts by mass of the lower adhesive.

  Here, the step of preparing the laminated film includes a step of forming the upper layer-side adhesive layer on the design film by laminating the upper layer-side adhesive on the design film, and a step of forming the upper layer side adhesive by heating the design film. Adhering the layer to the design film.

  Further, by laminating a lower adhesive composition containing a lower adhesive, an inorganic pigment and a solvent on a metal plate, a lower adhesive layer is formed, and by heating the metal plate, the lower adhesive layer is formed. The solvent contained may be evaporated and the lower adhesive layer may be adhered to the metal plate.

  Further, the lower adhesive layer may be adhered to the metal plate by heating the metal plate to a heating temperature of more than 180 ° C.

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

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

  Further, the lower-layer adhesive and the upper-layer adhesive may be composed of at least one of polyester-based, acrylic-based, urethane-based, epoxy-based, and urea-based thermosetting adhesives.

  Further, the lower layer adhesive and the upper layer adhesive are a polyester resin obtained by adding 3 to 25 parts by mass of a polyisocyanate resin having an isocyanate group of 30 mol% or more based on all dicarboxylic acid residues to 100 parts by mass of a linear polyester resin. It may be a thermosetting adhesive.

  Further, the lower adhesive layer, a lower adhesive composition containing an inorganic pigment and a silane coupling agent is laminated on a metal plate to form a lower adhesive layer, and the silane coupling agent is It may be contained in the lower adhesive composition at a ratio of 2 to 15 parts by mass with respect to 100 parts by mass.

  Further, the design film may be composed of any one or more of a vinyl chloride resin, a polyester resin, an acrylic resin, a polyolefin resin, and a fluororesin.

  Further, the design film may be made of a vinyl chloride resin.

  In addition, the softening temperature of a portion of the design film that is in contact with the upper adhesive layer may be lower than 150 ° C.

  According to another aspect of the present invention, a metal plate, a multi-layer adhesive for a design metal plate for bonding a design film, wherein the multi-layer adhesive for a design metal plate is an upper adhesive layer in contact with the design film, A lower adhesive layer in contact with the metal plate, the lower adhesive layer includes a lower adhesive and an inorganic pigment, the upper adhesive layer includes an upper adhesive, and the softening temperature of the upper adhesive is 80. ° C or less, the softening temperature of the lower adhesive is 90 ° C or more, and the lower adhesive layer contains 3 to 50 parts by mass of the inorganic pigment with respect to 100 parts by mass of the lower adhesive. A multilayer adhesive for a design metal plate is provided.

  According to another aspect of the present invention, among the multi-layer adhesive for a design metal plate that bonds a metal plate and a design film, the composition for a lower adhesion layer constituting the lower adhesion layer in contact with the metal plate is provided. The lower adhesive layer composition contains a lower adhesive and an inorganic pigment, the softening temperature of the lower adhesive is 90 ° C. or higher, and the lower adhesive layer composition is 100 parts by mass of the lower adhesive. A composition for lower adhesive layer, comprising 3 to 50 parts by mass of an inorganic pigment.

  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 to maintain the design film even in a harsh environment of high temperature and high humidity. The adhesion to the metal plate can be maintained. Further, since the lower adhesive layer contains 3 to 50 parts by mass of the inorganic pigment with respect to 100 parts by mass of the lower adhesive, the concealing property can be maintained even when the design film is made thin.

It is a side view which shows schematic structure of the design metal plate which concerns on embodiment of this invention. 4 is a graph showing the correspondence between the temperature of the adhesive and the degree of softening. 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 the specification and the drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

<1. Configuration of Design Metal Plate>
First, the configuration 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 adhesive layer 41 laminated on the metal plate 20 and an upper adhesive layer 42 laminated on the lower 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. Configuration of Steel Plate)
The type of the metal plate 20 is not particularly limited, and a widely known metal plate can be used. Examples of the metal plate 20 include a steel plate, a stainless steel plate, an Al plate, a Cu plate, a brass plate, a Ti plate, a chromium plate, a nickel plate, a zinc plate, and a magnesium plate.

  Here, examples of the steel sheet include tin sheet, thin tin-plated steel sheet, electrolytic chromic acid-treated steel sheet (tin-free steel sheet), steel sheet for cans such as nickel-plated steel sheet, hot-dip galvanized steel sheet, hot-dip zinc-iron alloy-plated steel sheet, Hot-dip galvanized steel sheet such as hot-dip zinc-aluminum-magnesium alloy coated steel sheet, hot-dip aluminum-silicon alloy coated steel sheet, hot-dip lead-tin alloy coated steel sheet, electro-galvanized steel sheet, electric zinc-nickel plated steel sheet, electric zinc-iron alloy-coated steel sheet And electroplated steel sheets, such as electro-zinc-chromium alloy-plated steel sheets, and cold-rolled steel sheets. The coating on the steel sheet may be performed on either one side or both sides.

  The surface of the steel sheet may be subjected to various chemical treatments for the purpose of enhancing adhesion to 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, and various inorganic coatings (for example, vanadium, titanium, zirconium, aluminum, magnesium) , A phosphorus-containing inorganic coating), a coating of various organic coatings (for example, an organic coating containing a polyacrylic resin, a urethane resin, an acrylic resin, etc.), a coating of a silane coupling agent, and the like. No.

  In the present embodiment, since the lower adhesive (the adhesive contained in the lower adhesive layer 41) is softened at a high temperature, it is possible to suppress the entry of water molecules into the lower adhesive layer 41. Therefore, even in a high-temperature and high-humidity environment, the adhesion (secondary adhesion) 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, colors, patterns, embosses, and the like). Examples of the design film 30 include a monochrome design film, a pattern design film, and the like. The monochromatic design film is a design film colored with a pigment. The surface of the monochromatic design film is often embossed. Light reflection is suppressed by such embossing. The pattern design film is a design film on which coloring with a pigment and printing of a pattern have been performed. A transparent protective film for protecting the pattern may be further laminated on the surface of the pattern design film. In some cases, the pattern design film is produced by pressing a colored film colored with a pigment and a transparent protective film on which a pattern is printed. In this case, the pattern printing surface of the transparent protective film is directed to the colored film side.

  In the present embodiment, the upper adhesive (the adhesive contained in the upper adhesive layer 42) softens at a low temperature. Therefore, even when the heating temperature for softening the upper adhesive is low, the design film 30 can be sufficiently adhered to the upper adhesive layer 42. 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 the deterioration of the design applied to the design film 30.

(1-2-1. Resin constituting design film)
The resin constituting the design film 30 is not particularly limited. That is, any resin applicable to a conventional design film can be applied to the design film 30 of the present embodiment. Examples of the resin constituting the design film 30 include a thermoplastic resin and a thermosetting resin. Examples of the thermoplastic resin include a vinyl chloride resin, a polyester resin, an acrylic resin, a polyolefin resin, and a fluororesin. Examples of the thermosetting resin include a urethane resin, a urea resin, and an epoxy resin. The design film 30 is preferably composed of at least one of a vinyl chloride resin, a polyester resin, an acrylic resin, a polyolefin resin, and a fluorine-based resin among the resins described above. The design film 30 composed of these resins is excellent in print wettability and embossability, so that it is easy to give a high-grade design. Although details will be described later, when the design film 30 is made of a vinyl chloride resin, the effects of the present embodiment are more remarkably obtained. Hereinafter, examples of preferred resins will be described in detail.

  The 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, and 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-acrylonitrile copolymer Copolymer, vinyl chloride-butadiene copolymer, vinyl chloride-isoprene copolymer, vinyl chloride-chlorinated propylene copolymer, vinyl chloride-vinylidene chloride-vinyl acetate terpolymer, vinyl chloride-maleate copolymer Copolymer, vinyl chloride-methacrylic acid ester copolymer, vinyl chloride-acrylonitrile copolymer , Vinyl chloride-various vinyl ether copolymers and other chlorine-containing resins, and blends thereof or other synthetic resins containing no chlorine, such as acrylonitrile-styrene copolymers, ethylene-vinyl acetate copolymers , An ethylene-ethyl (meth) acrylate copolymer, a blend with polyester and the like, a block copolymer, a graft copolymer and the like.

  Further, when the design film 30 containing a vinyl chloride resin as a main component is manufactured, the design film 30 includes a chlorine-free diene resin, 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), acrylic resins, and fluorine-free resins such as 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 at a mass ratio of 50% by mass or more with respect to the total mass of the design film 30. The amount of these additives is preferably less than 50% by mass based on the total mass of the design film 30. When the amount of the additive is 50% by mass or more, the characteristics of the vinyl chloride resin may not be easily exhibited. Further, the amount of these additives is preferably 3% by mass or more based on the total mass of the design film 30. If the amount is less than 3% by mass, the film may be broken when an impact force is applied to the design metal plate.

  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 of the design film 30. Examples of additives include phthalate-based plasticizers such as diheptyl phthalate, dioctyl phthalate, and diisononyl phthalate; adipate-based plasticizers such as dioctyl adipate, diisononyl adipate, and di (butyldiglycol) adipate; and phosphates such as tricresyl phosphate. Plasticizers, polyester plasticizers, chlorinated paraffin plasticizers, trimellitate plasticizers, pyromellitate plasticizers, biphenyltetracarboxylate plasticizers, and epoxy plasticizers. The added 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 more than 30% by mass, a large amount of the plasticizer may move to the surface when the design metal plate 10 is used for a long time. In this case, the design property and the surface function may be deteriorated, for example, the surface may be tacky. The amount of the plasticizer added 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 design metal plate is processed, the film does not follow and may cause cracks.

  When a design film 30 containing a vinyl chloride resin as a main component is produced, the design film 30 may contain an organic acid such as barium stearate for the purpose of improving thermal stability, weather resistance, concealment, 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 ultraviolet absorbers such as 2,4-dihydroxybenzophenone May be added. The amount of these additives is preferably 0.01 to 10% by mass based on the total mass of the design film 30. When the addition amount is less than 0.01% by mass, the function of the additive may not be sufficiently exhibited. On the other hand, when the addition amount is more than 10% by mass, coloring and burning may occur.

  In the case of producing a 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 imparting hiding power to the design film 30. Is also good. The amount of the pigment added is preferably 1 to 30% by mass based on the total mass of the design film 30. When the addition amount is less than 1% by mass, the concealing property may be insufficient. When the addition amount is more than 30% by mass, the design film 30 becomes brittle, and it may be difficult to form a film. From the viewpoint of film forming properties and stability of hiding, the amount of the pigment added is more preferably 5 to 20% by mass.

  When the design film 30 containing a vinyl chloride resin as a main component is produced, the design film 30 may contain, as additives other than the above, diphenylthiourea, diphenylurea, anilinodithiotriazine, melamine, benzoic acid, cinnamic acid, p Stabilizers such as tert-butylbenzoic acid and zeolites may be added. If necessary, the design film 30 may include a crosslinking agent, a foaming agent, an antistatic agent, an antifogging agent, a plate-out preventing agent, a surface treatment agent, a lubricant, a flame retardant, a fluorescent agent, a fungicide, a bactericide, and a metal. Additives such as an inert agent, a release agent, a pigment, a processing aid, an antioxidant, and a light stabilizer may be added. The amount of these additives is preferably 0.1 to 5% by mass based on the total mass of the design film 30. When the addition 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, characteristics such as mechanical strength of the design film 30 may be reduced.

  Examples of the polyester resin include a polyester resin composed of a diol compound residue and a dicarboxylic acid compound residue, and a polyester resin in which some or all of these are substituted with a hydroxyl carboxylic acid compound residue. More specific examples include PET (polyethylene terephthalate), PBT (polybutylene terephthalate), PET-I, PBT-I, PET-G, PCT-G, and PAr (polyarylate). Examples thereof include a polymer resin and a mixture of two or more of these.

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

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

  Examples of the polyolefin resin include a polyethylene resin, a polypropylene resin, an 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 (ethylene hexafluoropropylene) and the like. In addition to a resin having a suitable 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 given. Examples of the copolymer of a fluorine-containing monomer and an olefin include ETFE (copolymer of tetrafluoroethylene and ethylene). Examples of the copolymer of a fluorine-containing monomer and a chlorine-containing monomer include PCTFE (polychlorotrifluoroethylene) and ECTFE (copolymer of ethylene and chlorotrifluoroethylene).

  Among the above-listed resins, particularly preferred resins are vinyl chloride resin, PET, PBT, PET-G, PET-I, PBT-I, PVF, PVDF, acrylic resin containing methyl methacrylate as a main component, Polyethylene resin and polypropylene resin. The design film 30 composed mainly of these resins is particularly excellent in the wettability and embossability of printing, and the design film 30 composed of these resins 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 analyzer. Specifically, a cylindrical needle having a diameter of 1 mm is pushed into the sample with a load of 500 mN while heating the sample at 2 ° C./min. The temperature at which the penetration depth of the cylindrical needle into the sample satisfies the following equation (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 equation (1), t _i is the penetration depth, and t ₂₀₀ is the penetration depth when the sample temperature reaches 200 ° C. Therefore, the left side of Expression (1) indicates the degree of softening.

  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 lower than 150 ° C., the design film 30 and the upper The adhesion to the adhesive layer 42 can be improved. That is, even when the adhesive layer contact portion is heated to a temperature of 180 ° C. or lower, it is sufficiently softened, so that the adhesive force with the upper adhesive layer 42 can be improved. In other words, the adhesive layer contact portion can exhibit a sufficient anchor effect. Further, since the heating temperature of the design film 30 is equal to or lower than 180 ° C., the 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, an acrylic resin containing methyl methacrylate as a main component, a polyethylene resin, and the like. Therefore, the adhesive layer contact portion may be formed with these resins.

(1-2-3. Design Film Thickness)
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 less likely to exhibit the anchor effect unless the heating temperature is increased. For this reason, when manufacturing a design metal plate, it is necessary to press-bond a design film to a high-temperature adhesive layer. Therefore, when the thickness of the design film is less than 80 μm, large heat is conducted to the surface of the design film when the design film is pressed against the adhesive layer. The design on the surface of the design film is deteriorated by the heat. 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, when the design film has a thickness of 200 μm or more, a large thermal stress is generated due to a difference in thermal expansion between the steel plate and the design film when the design film is pressed against a steel plate. As a result, the adhesion by the adhesive is reduced. In addition, the design film may be warped.

  In contrast, in the present embodiment, the upper adhesive contained in the upper adhesive layer 42 (that is, the adhesive layer on the design film 30 side) softens at a low temperature. Therefore, in the present embodiment, even when the temperature of the upper adhesive layer 42 is low, the upper adhesive layer 42 and the design film 30 can be sufficiently adhered to each other. That is, the heat conducted to the design film 30 can be reduced. For this reason, 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, even if the thickness of the design film 30 is 200 μm or more, the stress generated due to the difference in thermal expansion between the metal plate 20 and the design film 30. Can be reduced. That is, even if the thickness of the design film 30 is 200 μm or more, it is possible to suppress a decrease in adhesion and warpage 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 be increased. For this reason, it is preferable that the thickness of the design film 30 be 5 to 400 μm.

(1-3. Configuration 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 adhesive layer 41 includes a lower adhesive and an inorganic pigment, and the upper adhesive layer 42 includes an upper adhesive. The softening temperature (T _under ) of the lower adhesive is 90 ° C. or more, and the softening temperature (T _up ) of the upper adhesive is 80 ° C. or less. In the case where the adhesive is a thermosetting adhesive, a value measured on a film composed of only the main adhesive containing no curing agent is defined as the softening temperature of the adhesive.

  As described above, since the upper layer adhesive is sufficiently softened at a low temperature (for example, at a temperature of 180 ° C. or less), even when the low temperature upper layer adhesive layer 42 and the design film 30 are brought into close contact with each other, the upper layer adhesive is formed. The anchor effect of the agent on the design film 30 can be sufficiently exhibited. That is, the upper-layer-side adhesive penetrates deeply into the irregularities of the design film 30, and a sufficient contact area with the design film 30 can be secured. As a result, the design film 30 and the upper-side adhesive layer 42 can be brought into close contact with each other with a sufficiently strong adhesion force that can withstand bending and overhanging. Further, since the heat conducted to the design film 30 can be reduced, the deterioration of the design applied to the design film 30 can be suppressed.

  Further, since the lower adhesive is softened at a high temperature, even if the design metal plate 10 is exposed to a high-temperature and high-humidity environment for a long time, water molecules can be suppressed from entering the lower adhesive layer 41. Therefore, chemical bonding between the lower adhesive layer 41 and the metal plate 20 can be maintained. Here, although the lower adhesive layer 41 is exposed from the end surface of the design metal plate 10, 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 enter the lower adhesive layer 41, they cannot reach the interface between the lower adhesive layer 41 and the metal plate 20. Further, it is presumed that 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 accelerated test by the present inventor causes peeling of the design film 30 at the interface between the steel sheet and the adhesive layer. Therefore, even when the design metal plate 10 is exposed to a high-temperature and high-humidity environment for a long time, the secondary adhesion can be maintained for a long 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 at the time of manufacturing the design metal plate 10 and to perform the design even in a severe environment of high temperature and high humidity. The adhesion between the film 30 and the metal plate 20 can be maintained. Therefore, the design film 30 can be manufactured with almost no consideration of the influence of heat (for example, deterioration of the design) on the design film 30. 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 design metal plate in a high-temperature and high-humidity environment. However, in this case, it is necessary to press-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 the influence of such heat. For example, it is necessary to perform operations 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 to be pressed against the design film 30 is made of an adhesive having a low softening temperature. Therefore, there is almost no need to consider the influence of heat when manufacturing the design film 30. For this reason, for example, the range of material choices 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 adhesive is preferably 70 ° C. or less. In this case, the upper layer adhesive is sufficiently softened even at a low heating temperature such as 165 ° C. or less. Therefore, even when the upper adhesive layer 42 heated to this temperature is brought into close contact with the design film 30, the anchor effect of the upper adhesive on the design film 30 can be sufficiently exhibited.

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

(1-3-1. Inorganic pigment)
The lower adhesive layer 41 contains an inorganic pigment in addition to the lower adhesive. The present inventor paid attention to inorganic pigments in order to enhance the concealing property when the design film 30 is made thinner. The inventor added an inorganic pigment to the upper adhesive layer 42. As a result, the concealing property was certainly improved, but the design film 30 was easily peeled off from the adhesive layer 40. Specifically, the initial adhesion described below significantly decreased. This tendency was particularly noticeable when the design film 30 was made of a vinyl chloride resin, that is, when the design film 30 was a vinyl chloride film. Then, the present inventor washed the surface of the vinyl chloride film with methyl ethyl ketone (MEK), and then attached the design film 30 to the adhesive layer 40. As a result, the initial adhesion was slightly improved. As a result, the present inventor thought that the plasticizer contained in the vinyl chloride film was one of the causes of the decrease in the initial adhesion. This is because the plasticizer contained in the vinyl chloride film has a very low compatibility with the inorganic pigment and easily segregates on the surface of the vinyl chloride film. That is, it is considered that the plasticizer segregated on the surface of the vinyl chloride film lowered the initial adhesion of the design film 30. Then, a part of the plasticizer is removed by washing the surface of the vinyl chloride film with methyl ethyl ketone. As a result, it is considered that the initial adhesion of the design film 30 was slightly improved. However, the initial adhesion of the design film 30 still did not become sufficiently high.

  Then, the present inventor decided to add an inorganic pigment to the lower adhesive layer 41. As a result, even when the design film 30 was a vinyl chloride film, the initial adhesion was large and the concealing property was high. Thus, in the present embodiment, the lower adhesive layer 41 contains the inorganic pigment. The type of the design film 30 is not particularly limited, but when the design film 30 is a vinyl chloride film, the effects of the present embodiment are remarkably obtained.

  The lower adhesive layer 41 contains 3 to 50 parts by mass of an inorganic pigment based on 100 parts by mass of the lower adhesive. When the content of the inorganic pigment is less than 3 parts by mass, there is a possibility that a sufficient hiding property cannot be secured unless the lower adhesive layer 41 is made thick. When the lower adhesive layer 41 is made thicker, the manufacturing cost of the design metal plate 10 increases. Further, when the design metal plate 10 is bent or the like, the lower adhesive layer 41 may undergo large shear deformation, and the design of the design film 20 may be deformed.

  When the content of the inorganic pigment exceeds 50 parts by mass, the viscosity of the lower adhesive composition may be too high, and the lower adhesive composition may not be uniformly applied on the metal plate 20. In addition, the adhesion between the lower adhesive layer 41 and the metal plate 30 may be reduced. Here, the lower adhesive composition serves as a coating liquid when the lower adhesive layer 41 is formed on the metal plate 20. The content of the inorganic pigment is preferably 25 to 50 parts by mass from the viewpoint of the balance between the hiding property, the coating property, and the adhesion. In addition, when the content of the inorganic pigment is 50 parts by mass, the mechanical strength of the adhesive layer is slightly reduced. Therefore, the content of the inorganic pigment is more preferably 25 parts by mass or more and less than 50 parts by mass. The content of the inorganic pigment is more preferably 30 to 45 parts by mass. Preferably, no inorganic pigment is added to the upper adhesive layer 42. This is because the adhesion to the design film 30 is reduced.

  The average particle size of the inorganic pigment is preferably 1 μm or less. When the average particle size of the inorganic pigment exceeds 1 μm, the dispersibility in the lower adhesive layer 41 of the inorganic pigment is reduced, so that the concealing property may be reduced. Further, the mechanical strength of the lower adhesive layer 41 may be reduced, and the adhesive layer 40 may be cohesively broken. The average particle size of the inorganic pigment is more preferably from 0.2 to 0.4 μm. As shown in the examples described later, when the average particle size was within this range, the concealing property was enhanced. When the average particle size is 0.4 μm, the concealing property is slightly lowered. Therefore, the average particle size is more preferably less than 0.4 μm. It is considered that the scattering cross section increases when the average particle size is a value within this range. When the average particle size of the inorganic pigment is less than 0.2 μm, the inorganic pigment may not be able to scatter visible light having a small wavelength. As a result, the concealability may be reduced. On the other hand, when the average particle size of the inorganic pigment exceeds 0.4 μm, the mechanical strength of the lower adhesive layer 41 decreases, and the adhesive layer 40 may be cohesively broken. From the viewpoints of hiding power and mechanical strength, the average particle size of the inorganic pigment is more preferably from 0.2 to 0.3 μm. In this case, a sufficient amount of the inorganic pigment can secure sufficient hiding power, and the mechanical strength of the lower adhesive layer 41 can be increased. The average particle size of the inorganic pigment is a D50 value (volume basis) of the particle size. The particle size of the inorganic pigment is a so-called sphere equivalent diameter, and is measured by a laser scattering method or the like.

  The inorganic pigment that can be used in the present embodiment is not particularly limited, and a known white or colored pigment can be widely used. Examples of inorganic pigments include inorganic white pigments such as titanium dioxide, zinc white, gloss white, barite, precipitated barium sulfate, calcium carbonate, gypsum, precipitated silica, aerosil, talc, calcined or unfired clay, barium carbonate. , White pigments such as alumina white, synthetic or natural mica, synthetic calcium silicate, magnesium carbonate, etc., black pigments such as carbon black and gnetite, red pigments such as redwood, yellow pigments such as siena, ultramarine, cobalt blue and the like. Blue pigments can be mentioned. One or more of these inorganic pigments may be added to the lower adhesive layer 41. Among these inorganic pigments, titanium dioxide is particularly preferable from the viewpoint of concealing the surface of the metal plate 20, raising the color tone of the design film 30, and raising the printing ink.

  Here, titanium dioxide is classified into rutile type, anase type and brookite type according to its crystal structure. In the present embodiment, from the viewpoint of whiteness and the like, rutile-type titanium dioxide is particularly preferable. Further, the refractive index of the rutile type titanium dioxide (D) is preferably from 2.0 to 2.7, more preferably from 2.4 to 2.7, from the viewpoint of whiteness. Here, the refractive index of the rutile type titanium dioxide is a value measured by an Abbe refractometer described in JIS K0062.

  The titanium dioxide may be subjected to a surface treatment using an inorganic substance, an organic substance, or both of them in order to improve the affinity with the lower layer side adhesive. Examples of the surface treatment include, for example, aluminum, zirconium, tin, titanium, cerium, zinc, an inorganic surface treatment for forming a metal oxide film on the surface of titanium dioxide by using a phosphate, a fatty acid salt, or an oxide of a metal such as iron; An organic surface treatment of modifying the surface of titanium dioxide with an organic group such as an alkyl group using a silicon-based organic compound such as a siloxane-based or silane-based compound, a polyol-based compound, or an amine-based compound can be given. Among these surface treatments, an organic surface treatment is more preferable.

  In the present embodiment, a commercially available inorganic pigment may be used. For example, commercially available titanium dioxide includes Tipaqre CR-50, R-630, R-550, R-820, R-930, CR-80, R-830, CR-97, CR-90, CR-93, CR -95, CR-58, CR-67, R-580, R-670 (manufactured by Ishihara Sangyo Co., Ltd.), Titanix JR-600A, AR-600E, JRNC, JR-602, JR-701, JR-603, JR-805 , JR-300 (manufactured by Teika Co., Ltd.), Titon R-650, R-5N, R-61N, R-52N, R-62N, SR-1, R-GL, TCR-37, TCR-10, TCR- 17, TCR-61, TCR-57, TCR-11 (manufactured by Sakai Chemical Co., Ltd.), Kronos KR-380, KR-380N, KR-310 (manufactured by Titanium Industry Co., Ltd.), FR-22, FR 41, FR-35, FR-44, FR-46 (manufactured by Furukawa Kikai Metals), TR-700, TR-840 (manufactured by Fuji Titanium), Ti-PureR-900, R-920, R-902, R -960, R-901 (manufactured by Dupont Group), TioxideR-HD2, R-HD6, R-TC4, R-HD3, R-TC90, R-CR2, R-CR3, R-CR6, R-TC60, R -TCY, R-CR60, R-TC90 (manufactured by Tioxide Group) and the like.

(1-3-2. Specific examples of 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 softening temperature condition. Examples of the adhesive constituting the lower-layer adhesive and the upper-layer adhesive include a solvent-based adhesive, an aqueous adhesive, a hot-melt adhesive, an elastic adhesive, a thermosetting (thermosetting reaction) adhesive, Examples include a pressure-sensitive adhesive and a natural adhesive.

  Examples of the solvent-based adhesive include a rubber-based adhesive and a resin-based adhesive. 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 a vinyl acetate resin adhesive, a urethane resin adhesive, and an ethylene vinyl acetate copolymer resin adhesive.

  Examples of the water-based adhesive include a water-soluble adhesive, an emulsion-based adhesive, and a latex-based adhesive. Examples of the water-soluble adhesive include starch glue, poval glue, an aqueous polymer-isocyanate adhesive, a polyvinylpyrrolidone adhesive, and a gum arabic adhesive. Examples of the emulsion adhesive include an emulsion adhesive composed of a vinyl acetate resin emulsion, an EVA resin emulsion, an acrylic emulsion, a urethane emulsion, and the like. Examples of the latex-based adhesive include a latex-based adhesive made from rubber such as chloroprene rubber.

  Examples of the hot-melt adhesive include hot-melt adhesives of thermoplastic elastomer type, EVA (ethylene-vinyl acetate copolymer) type, olefin type, polyamide type, urethane type and polyester type. Here, examples of the thermoplastic elastomer hot melt adhesive include thermoplastic elastomer hot melt adhesives mainly composed of synthetic rubber such as SBS (styrene-butadiene-styrene) and SIS (styrene-isoprene-styrene). An adhesive and the like can be mentioned. Examples of the olefin-based hot-melt adhesive include an olefin-based hot-melt adhesive mainly composed of amorphous polypropylene.

  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 in which a hydrolyzable silyl group is introduced into various polyethers, 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, and urethane-based, urea-based, melamine-based, phenol-based, acrylic-based, cyanoacrylate-based, and polyester-based thermosetting adhesives. Cured adhesives and the like can be mentioned.

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

  Among the adhesives listed above, particularly preferred adhesives are thermosetting adhesives of polyester type, acrylic type, urethane type, epoxy type and urea type. 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 stability against heat and humidity. Further, among these adhesives, a polyester-based thermosetting adhesive is particularly preferable. This is because the adhesive is particularly excellent in handling properties, adhesion, and strength of the adhesive itself, in addition to the above properties. Hereinafter, the polyester-based thermosetting adhesive will be described in detail.

  As a polyester-based thermosetting adhesive, a polyester resin, a urethane-modified polyester resin obtained by blending a polyisocyanate compound with a polyester diol, 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. And an adhesive crosslinked by a crosslinking agent such as a blocked isocyanate compound and an amino resin.

  Here, examples of the polyester resin as the main component include a polyester resin including a dicarboxylic acid residue and a diol residue. Examples of dicarboxylic acid residues include terephthalic acid residues, isophthalic acid residues, aromatic carboxylic acid residues such as α- or β-naphthalenedicarboxylic acid residues, succinic acid residues, and glutaric acid residues. Residue, adipic acid residue, pimelic acid residue, suberic acid residue, azelaic acid residue, sebacic acid residue, aliphatic dicarboxylic acid residue such as undecylenic acid residue, 1,4-cyclohexanedicarboxylic acid residue 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. Group, trimethylolethane residue and the like.

  Examples of the polyester diol include polyester diols in which both terminals 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 and bisphenol F-type epoxy-modified polyester resins.

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

  Examples of the blocked isocyanate compound include isocyanates obtained by blocking each of the above isocyanate compounds with the following isocyanate blocking agent. Here, examples of the isocyanate blocking agent include phenol-based blocking agents such as phenol, thiophenol, methylthiophenol, cresol, xylenol, resorcinol, nitrophenol, and chlorophenol, and oxime-based blocks such as acetoxime, methylethylketoxime, and cyclohexanone oxime. Alcohol blocking agents such as methanol, ethanol, propanol and butanol, halogen-substituted alcohol blocking agents such as ethylene chlorohydrin and 1,3-dichloro-2-propanol, and t-butanol and t-pentanol. Lactam-based blocking agents such as tertiary alcohol-based blocking agents, ε-caprolactam, δ-valerolactam, γ-butyrolactam, and β-propyllactam are exemplified. Other examples of the blocking agent include aromatic amines, imides, acetylacetone, acetoacetate ester, active methylene compounds such as malonic acid ethyl ester, mercaptans, imines, ureas, diaryl compounds and sodium bisulfite. No.

  Examples of the amino resin include urea, melamine, an amino resin obtained by a condensation reaction of a compound containing an amino group such as benzoguanamine with formaldehyde, and furthermore, an amino resin having 1 to 6 carbon atoms and an alcohol having 1 to 6 carbon atoms. Examples thereof include an alkyl ether compound obtained by a 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 Benzoguanamine and the like.

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

  Among the above-mentioned polyester-based thermosetting adhesives, a particularly preferred example is a polyisocyanate having 2 or more isocyanate groups with respect to 100 parts by mass of a linear polyester resin comprising an aromatic dicarboxylic acid and a diol residue, having 3 to 25 parts by mass. It is a polyester-based thermosetting adhesive to which parts are added. This polyester-based thermosetting adhesive is particularly excellent in affinity with the metal plate 20 and the design film 30. Further, since the polyester-based thermosetting adhesive has a strong self-cohesive force and a high strength of the adhesive itself, the cohesive failure of the adhesive can be prevented.

  Further, by adding 3 parts by mass or more of the polyisocyanate to the linear polyester resin, crosslinking can be further promoted during heating. For this reason, the cohesive force is further increased. Further, by setting the addition amount of the polyisocyanate to 25 parts by mass or less, appropriate ductility can be imparted to the polyester-based thermosetting adhesive. For this reason, the processability of the polyester-based thermosetting adhesive can be improved. When a 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, examples of the linear polyester resin include an aromatic carboxylic acid residue containing a terephthalic acid residue and an ethylene glycol residue, a neopentyl glycol residue, or a 2-methyl-1,3-propanediol residue. And a diol residue. Here, the linear polyester resin preferably contains at least 30 mol% of terephthalic acid residues 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 residual stress due to thermal strain or the like applied during lamination decreases. Therefore, when the design metal plate 10 is exposed to a high-temperature and high-humidity environment for a long time, the adhesive itself may be broken and peeled off. Further, the linear polyester resin preferably contains the above diol residue in an amount of 60 mol% or more based on all diol residues. If the content is less than 60 mol%, the solubility of the polyester-based thermosetting adhesive in a solvent may be poor, and the adhesive concentration in the pot may not be constant.

  In addition, various additives and fillers other than the coloring pigment can also be added to the adhesive layer 40. Such additives and fillers include, for example, organic compounds, inorganic compounds, anticorrosive pigments composed of metal oxides, extender pigments, benzophenone-based, benzotriazole-based, triazine-based ultraviolet absorbers, hindered amines -Based light stabilizer, hindered phenol-based, phosphorus-based, sulfur-based, tocopherol-based antioxidant, epoxysilane-based, vinylsilane-based, mercaptosilane-based, aminosilane-based silane coupling agent, rosin resin, xylene resin , An adhesive imparting agent such as an epoxy resin, super particles such as anhydrous silica, a flame retardant, a viscosity modifier, a coating film reinforcing agent, an antifoaming agent, a surface smoothing agent, and the like.

  In particular, it is preferable that a silane coupling agent is added to the lower adhesive layer 41 in order to enhance the adhesion to the metal plate 20. That is, the silane coupling agent can increase the adhesion between the lower adhesive layer 41 and the metal plate 20 by binding the molecules of the lower adhesive. 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 adhesive. When the addition amount of the silane coupling agent is less than 2 parts by mass, the effect of improving the adhesion to the metal plate 20 is small. If the 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 the water-resistant adhesion, it is preferable that the silane coupling agent is made organic by reaction with maleic anhydride. When a hydroxyl group is present on the surface of the inorganic pigment, the silane coupling agent can react with the hydroxyl group. Thereby, the silane coupling agent can further enhance the dispersibility and the like of the inorganic pigment.

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

(1-3-4. Layer structure)
One or more other adhesive layers may be interposed between the lower adhesive layer 41 and the upper adhesive layer 42.

<2. Manufacturing method of design metal plate>
The method of manufacturing the design metal plate 10 includes a step in which the design film is laminated on the steel sheet, and a step in which an adhesive is laminated on the design film, in these steps, the temperature at which the design film is heated is 180 ° C. or less. If there is, there is no particular limitation. In the present embodiment, the design film is not heated to 180 ° C. or more in the laminating step. In addition, since the softening temperature of the upper adhesive forming the upper adhesive layer 42 is 80 ° C. or less, the upper adhesive is sufficiently softened even if the temperature of the metal plate 20 is 180 ° C. or less. Therefore, the design film 30 and the metal plate 20 can be firmly adhered. Specific examples of the method of manufacturing the design metal plate 10 include the following first example and second example.

(2-1. First Example)
In the first example, the design metal plate 10 is manufactured by the following steps. First, the lower adhesive layer 41 is formed on the metal plate 20 by applying the lower 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 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 adhesive layer 42 is formed on the lower adhesive layer 41 by applying the upper adhesive composition on the lower adhesive layer 41. Next, the upper layer side adhesive is softened by heating the metal plate 20 to a heating temperature of 180 ° C. or lower. Thus, in the present embodiment, the heating temperature of the metal plate 20 is reduced. However, as described above, since the softening temperature of the upper layer adhesive is low, the upper layer adhesive is sufficiently softened even at such a heating temperature. Further, since the low-temperature upper-side adhesive layer 42 can be pressure-bonded to the design film 30, the heat conducted to the design film 30 can be reduced. Therefore, deterioration of the design applied to the design film 30 can be suppressed. Next, the design film 30 is pressed against the upper adhesive layer 42. Thereby, the design 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 adhesive layer 41 is formed on the metal plate 20 by applying the lower adhesive composition on the metal plate 20. Next, by heating the metal plate 20, the lower-layer 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 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 adhesive layer 42 is formed on the design film 30 by applying the upper adhesive composition on the design film 30. Next, 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 layer side adhesive layer 42 adheres to the design film 30, that is, a temperature at which the upper layer adhesive exerts an anchor effect on the design film 30 and is 180 ° C. or less. No restrictions.

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

  The method of manufacturing the design metal plate 10 is not limited to the first example and the second example described above. That is, in the first and second examples 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 adhesive layer 41 and the upper 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 badge-type thermocompression device.

<3. Configuration Example of Design Metal Plate Manufacturing Apparatus>
(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 of 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 apparatus may be used as long as it is a manufacturing apparatus capable of manufacturing the design metal plate 10 having the above-described structure. For example, in the following manufacturing apparatuses 100 and 101, each adhesive layer is formed by a roll coater method. However, 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, a design film transport device 160, A pressure roll pair 163 and a cooling device 170 are provided.

  The transport device of 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 for laminating 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 that stores the lower layer adhesive composition 121 including the lower layer adhesive. The lower-layer adhesive composition 121 may include a solvent in addition to the lower-layer adhesive and the inorganic pigment, and may further include an additive that forms the lower-layer adhesive layer 41. Here, the solvent is used for the purpose of, for example, adjusting the viscosity of the lower adhesive, dispersing the inorganic pigment in the lower adhesive layer 41, and the like. The solvent is preferably an organic solvent, and more preferably an organic solvent having no hydroxyl group. The organic solvent having a hydroxyl group may react with a curing group such as isocyanate in the curing agent, and may hinder the storage stability of the adhesive. Examples of preferable organic solvents include aromatic hydrocarbons such as benzene, toluene, and xylene; ketones such as acetone, MEK (methyl ethyl ketone), isobutyl ketone, methylene isobutylene ketone, and cyclohexanone; methyl acetate, ethyl acetate, and butyl acetate; Esters such as cellosolve acetate; ethers such as diethylene ether, THF (tetrahydrofuran) and dioxane; halogenated hydrocarbons such as methylene chloride and ethylene chloride; dimethyl sulfoxide; dimethyl sulfamide; high-boiling naphtha; and mixtures thereof. And the like. The organic solvent may be composed of any one or more of these. From the viewpoint of the handleability of the lower adhesive composition 121, the organic solvent is preferably a mixed solvent of high-boiling naphtha and MEK. The mixing ratio (volume ratio) of high boiling naphtha and MEK is preferably high melting point naphtha / MEK = 150/10 to 100/50. When the high melting point naphtha becomes richer than the above range, the organic solvent becomes difficult to volatilize. Therefore, the organic solvent may remain in the lower adhesive layer 41 even after the lower adhesive layer 41 is laminated on the metal plate 20. On the other hand, when the MEK becomes richer than the above range, the volatilization rate of the organic solvent may be too high, and the lower adhesive composition 121 may not be uniformly applied to the metal plate 20.

  The lower adhesive composition 121 is obtained by kneading the lower adhesive, the inorganic pigment, and the solvent using various kneading apparatuses, for example. Examples of the kneading apparatus include a nanomill, a ball mill, a sand mill, a bead mill, an attritor, an impeller mill, a roller mill, and a pebble mill. This manufacturing method is, for example, a manufacturing method used in industry. At the experimental level, the lower-layer adhesive composition 121 can be prepared using a flask equipped with a stirring rod and a reflux condenser, as described in Examples described later. The lower adhesive composition 121 may include a silane coupling agent. In this case, together with the silane coupling agent, a catalyst (a catalyst for reacting the silane coupling agent with a hydroxyl group of the lower adhesive molecule or a hydroxyl group on the surface of the inorganic pigment) may be included in the lower adhesive composition 121. These are preferably introduced into the kneading device simultaneously with the inorganic pigment.

  The pickup roll 122 picks up the lower layer adhesive composition 121 from the coater pan 121 a 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 transports the metal plate 20 to the first oven 130.

  The first oven 130 makes the lower adhesive layer 41 adhere to the metal plate 20 by heating the metal plate 20. Here, the heating temperature of the metal plate 20 is not particularly limited as long as the temperature at which the lower adhesive layer 41 adheres to the metal plate 20, that is, the temperature at which the lower adhesive exerts an anchor effect on the metal plate 20.

  For example, when the lower 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 adhesive is high, the lower layer adhesive can be sufficiently softened. As a result, the lower-layer-side adhesive penetrates deep into the irregularities of the metal plate 20 and can exhibit a strong anchoring effect.

  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 penetrates deep into the unevenness of the metal plate 20 and can exhibit a strong anchor effect. In this case, the heating temperature is lower, which is preferable. Further, in the manufacturing apparatus 100, the solvent is removed from the lower adhesive layer 41 before the upper adhesive layer 42 is formed by the second roll coater 140. Accordingly, 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 for laminating 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 that stores the upper layer adhesive composition 141 including the upper layer adhesive. The upper layer adhesive composition 141 may include a solvent in addition to the upper layer adhesive, and may further include an additive that forms the upper layer adhesive layer 42. Here, the solvent is used for the purpose of adjusting the viscosity of the upper layer side adhesive and the like. Examples of the solvent include the same examples as the solvent of the lower adhesive composition 121 described above.

  When the lower-layer adhesive and the upper-layer adhesive become adhesives that are cured by a curing agent, a catalyst that promotes curing may be added to the composition of each adhesive. In this case, the catalyst is preferably charged into the composition at the timing when the curing reaction starts.

  The pickup roll 142 picks up the upper-side adhesive composition 141 from the coater pan 141a and conveys it to the conveying roll 143. The transport roll 143 transports the upper adhesive composition 141 to the applicator roll 144. Note that 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 softens the upper layer adhesive by heating the metal plate 20 to a heating temperature of 180 ° C. or lower. Thus, in the present embodiment, the heating temperature of the metal plate 20 is reduced. However, as described above, since the softening temperature of the upper layer adhesive is low, the upper layer adhesive is sufficiently softened even at such a heating temperature. Further, since the low-temperature upper-side adhesive layer 42 can be pressure-bonded to the design film 30, the heat conducted to the design film 30 can be reduced. Therefore, 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 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, more preferably 140 ° C. or lower. When the softening temperature of the upper adhesive is 70 ° C. or lower, the upper 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 the deterioration of the design applied to the design film 30. In addition, 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 is lower than the temperature, the upper layer adhesive may not sufficiently soften in a short time at the time of laminating the design film, and the primary adhesion may decrease.

  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 the design film 30 to the pressure roll pair 163. The press roll pair 163 presses the design film 30 to the upper adhesive layer 42. Thereby, the design metal plate 10 is manufactured. The cooling device 170 is, for example, a water cooling tank, and cools the design metal plate 10.

(3-2. Second example)
The second example of the manufacturing method is realized by using, for example, a manufacturing apparatus 101 shown in FIG. Therefore, the configuration of the manufacturing apparatus 101 will be described. Here, the manufacturing apparatus 101 has the same configuration as the above-described manufacturing apparatus 100 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 forms the upper adhesive layer 42 on the design film 30 by applying the upper adhesive composition 141 to the design film 30.

  The second oven 150 makes the upper adhesive layer 42 adhere to the design film 30 by heating 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 upper layer adhesive layer 42 adheres to the design film 30, that is, a temperature at which the upper layer adhesive exerts an anchor effect on the design film 30. For example, the heating temperature of the design film 30 may be 180 ° C. or less.

  The pressure roll pair 163 presses the upper adhesive layer 42 on the design film 30 to the lower adhesive layer 41 on the metal plate 20 with the temperature of the metal plate 20 set to 180 ° C. or less. That is, the pressure-bonding roll pair 163 produces 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 adhesive is low, the upper adhesive is sufficiently softened even when the temperature of the metal plate 20 is 180 ° C. or lower. Further, since the low-temperature upper-side adhesive layer 42 can be pressure-bonded to the design film 30, the heat conducted to the design film 30 can be reduced. Therefore, deterioration of the design applied to the design film 30 can be suppressed.

  The temperature of the metal plate 20 can be further reduced according to the softening temperature of the upper layer 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, more preferably 140 ° C. or lower. When the softening temperature of the upper adhesive is 70 ° C. or lower, the upper adhesive is sufficiently softened even when the temperature of the metal plate 20 is within the above range. In addition, 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 for 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 less by adjusting the distance between the first oven 130 and the pair of press rolls 163. it can. That is, the temperature of the metal plate 20 may be set to 180 ° C. or lower by the residual heat of the first oven 130. A cooling device similar to the cooling device 170 may be provided 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 equal to or lower than 180 ° C., a separate oven may be provided between the first oven 130 and the press roll pair 163. This oven reheats the metal plate 20 to a temperature of 180 ° C. or less. 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 given from the design film 30 on which the upper adhesive layer 42 is laminated.

  Here, the design film 30 on which the upper adhesive layer 42 is laminated, that is, a laminated film is prepared in advance, and the upper adhesive layer 42 of the laminated film is brought into close contact with the lower adhesive layer 41 on the metal plate 20. Is also good. Alternatively, the metal plate 20 on which the lower adhesive layer 41 is laminated, that is, a laminated metal plate is prepared in advance and is brought into close contact with a prepared laminated film (or a 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 pressed against the metal plate 20 has an upper adhesive layer 42 / design film 30 and an upper adhesive layer 42 / The lower adhesive layer 41 is formed. Therefore, the manufacturing apparatuses 100 and 101 perform organic / organic bonding. Organic substances are easily deformed even at a heating temperature of 180 ° C. or lower, and easily exhibit a sufficient anchor effect. Therefore, also in this respect, the design film 30 and the metal plate 20 can be firmly adhered.

<1. Adjustment of adhesive composition>
(1-1. Production of Upper Layer Adhesive Main Agent)
An upper layer side adhesive main agent was prepared by the following steps. First, 200 parts by mass of a high-boiling naphtha (Solvesso 150) was charged into a flask equipped with a stirring rod and a reflux condenser, and stirred for about 10 minutes. Thereafter, 100 parts by mass of an adhesive main agent (any of polyester, acrylic, and urethane) was added, and the mixture was stirred and dissolved at room temperature for 4 hours. Here, the adhesive main agent constitutes the above-mentioned upper 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 charged, and the mixture was stirred for 30 minutes at room temperature. Through the above steps, an upper adhesive agent was prepared. The upper layer-side adhesive main agent is an adhesive main agent containing no inorganic pigment. The upper adhesive agent is mainly used for producing the upper adhesive layer, but may be used for producing the lower adhesive layer.

(1-2. Preparation of Lower Layer Adhesive Main Agent)
200 parts by mass of high-boiling naphtha (Solvesso 150) was charged into a flask equipped with a stirring rod and a reflux condenser, and stirred for about 10 minutes. Thereafter, 100 parts by mass of an adhesive main agent (any of polyester, acrylic, and urethane) was added, and the mixture was stirred and dissolved at room temperature for 4 hours. Here, the adhesive main agent constitutes the lower layer adhesive. After confirming that the adhesive main agent was completely dissolved, a predetermined amount of an inorganic pigment was added and the mixture was stirred for 1 hour at room temperature. Thereafter, 20 parts by mass of MEK (methyl ethyl ketone, manufactured by Maruzen Oil Co., Ltd.) was charged, and the mixture was stirred at room temperature for 30 minutes. To the adhesive to which the silane coupling agent was added, 5 parts by mass of a silane compound (KBM-402 manufactured by Shin-Etsu Chemical Co., Ltd.) was added at the timing when the inorganic pigment was charged. Thereafter, 20 parts by mass of MEK was charged and stirred at room temperature for 30 minutes. The lower layer-side adhesive main agent is an adhesive main agent containing an inorganic pigment. The lower adhesive agent is mainly used for producing the lower adhesive layer, but may be used for producing the upper adhesive layer.

(1-3. Preparation of curable adhesive composition)
A curable adhesive composition was obtained by blending a curing agent solution (Y6410-B manufactured by Yokohama Rubber Co., Ltd. or Desmodule RFE manufactured by Bayer) and a catalyst (U-CAT SA102 manufactured by San Apro Co.) with the above-mentioned adhesive main agent. . This catalyst is a catalyst for accelerating the curing of the main adhesive. Y6410-B is a polyisocyanate resin having an isocyanate group of 30 mol% based on all dicarboxylic acid residues. The amount of the curing agent solution was 4 parts by mass on a solid basis, and the amount of the catalyst was 0.1 part by mass on a solid basis relative to 1 part by mass of the curing agent. Tables 1 to 4 show the composition of the curable adhesive composition.

  The numerical values in Tables 1 to 4 mean parts by mass except for the softening temperature. The numerical value in parentheses in the column of the inorganic pigment means an average particle size (μm) of the inorganic pigment. The parts by mass of the curing agent solution and the catalyst mean parts by mass of the solid content. Tables 5 and 6 show the specific contents of the materials constituting each adhesive composition.

<2. Measurement of softening temperature>
The softening temperature of each of the adhesive compositions, specifically, the softening temperature of the main adhesive 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. Next, the thickness of the adhesive composition was made uniform in the container by gently tilting the container. Then, the container was kept horizontal and dried in a 20 ° C constant temperature room 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 inorganic pigment, the curing agent and the catalyst as the adhesive composition.

  Next, the softening temperature was measured using a thermomechanical analyzer. Specifically, a cylindrical needle having a diameter of 1 mm was pushed into the sample at a load of 500 mN while heating the adhesive film at 2 ° C./min. The temperature at which the penetration depth of the cylindrical needle into the adhesive film satisfies the above equation (1) was defined as the softening temperature. Tables 1 to 5 summarize the softening temperatures of the respective adhesive compositions.

<3. Production of design film>
A design film was prepared or produced by the following steps.
(3-1. Vinyl chloride film)
(3-1-1. Monochromatic embossed film)
LE301 manufactured by Okamoto Corporation was prepared as a monocolor embossed film made of vinyl chloride. The film thickness is 150 μm. The embossed film has a surface embossed pattern having a depth of 15 μm on the embossed film.

(3-1-2. High definition film)
A raw film was produced by forming a film of the resin composition used in producing the monochromatic film by a calendar method. Here, a mirror-finished raw film was produced by using a mirror-finished roll for the calendering method. Then, a polyester-based adhesive (S-580X manufactured by Sekisui Fuller Co., Ltd.) was applied to the raw film using a continuous laminator, and dried at 80 ° C. After drying, a 25 μm-thick biaxially stretched PET (polyethylene terephthalate) film having a grain pattern printed thereon was laminated on the adhesive-coated surface of the raw film so that the printed surface was in contact with the adhesive. Through the above steps, a high definition film was obtained. In addition, it was 140 degreeC when the softening temperature of the vinyl chloride film was measured. In addition, a plurality of types of vinyl chloride films having different film thicknesses were produced. Table 7 shows the thickness of the film.

<4. Metal plate>
As the metal plate, two types of zinc-based gold steel plates having a thickness of 0.45 mm (Nippon Steel & Sumitomo Metal Super Dimer (K08) (hereinafter also referred to as “SD steel plate”), GI steel plate (Z18)), Al plate (A5052, 1) .2 mm). Then, after performing an alkali degreasing treatment on these metal plates, a chromate solution was applied to form a chromate film of about 45 mg / m ^{2 on} the surface of the metal plates. Further, as other metal plates, a roughened Cu plate (70 μm, electrolytic copper foil plate) and a JIS H 4600 standard Ti plate (1 mm thick) subjected to vacuum annealing pickling finish were prepared.

<5. Production of design metal plate>
(5-1. Examples 1-36)
The design metal plates according to Examples 1 to 36 were produced by the following steps. First, a lower layer adhesive composition (lower layer adhesive layer composition) was applied to a metal plate with a coater so that the lower layer adhesive layer had a predetermined thickness. Next, the metal plate was heated to a lower layer heating temperature (detailed values are shown in a table described later). Thus, a lower adhesive layer was formed on the metal plate. After the metal plate was cooled to room temperature, the upper layer adhesive composition (upper layer adhesive composition) was applied onto the lower layer adhesive layer such that the thickness of the upper layer adhesive layer became a predetermined thickness. Then, the metal plate was heated to an upper layer heating temperature (detailed values are shown in a table described later) to form an 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 pressed onto the surface of the upper layer side adhesive layer. Through the above steps, a design metal plate was obtained. 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 an adhesive composition for the upper layer and an adhesive for the lower layer. In Examples 12 to 17, an acrylic adhesive composition was used as the adhesive composition for the upper layer and the adhesive composition for the lower layer. In Examples 18 to 36, different material-based adhesive compositions were used as the adhesive composition for the upper layer and the adhesive composition for the lower layer. A different metal plate was used for each example. In the following description, the design metal plate to which the monocolor embossed film is attached is also referred to as “monochrome embossed plate”, and the design metal plate to which the high definition film is attached is also referred to as “high definition image plate”.

(5-2. Example 37)
The design metal plate according to Example 37 was manufactured by the following steps. First, an adhesive composition for a lower layer was applied to a metal plate by a coater so as to have a thickness of 2 μm. Next, the metal plate was heated to the lower layer heating temperature. Thus, a lower adhesive layer was formed on the metal plate. Next, the metal plate was cooled to room temperature. On the other hand, an adhesive composition for an upper layer was applied on the above-mentioned vinyl chloride film by a coater so as to have a thickness of 2 μm. Next, the design film was heated to the upper layer heating temperature. Thus, an upper adhesive layer was formed on the vinyl chloride film. Thereafter, the design film was cooled to room temperature. Next, the metal plate on which the lower adhesive layer was formed was heated to the upper heating temperature, and the upper adhesive layer on the design film was pressed against the lower adhesive layer on the metal plate. Through the above steps, a design metal plate was obtained.

(5-3. Comparative Examples 1-4)
A design metal plate was produced in the same process as in Example 1, except that the adhesive layer was composed of only one layer. That is, an adhesive layer was formed on a metal plate by the same steps as in Example 1. Next, the metal plate was heated to a heating temperature (detailed values are shown in a table described later). Next, a vinyl chloride film was pressed on the adhesive layer. Through the above steps, a design metal plate was produced.

(5-4. Comparative Examples 5 to 10)
A design metal plate was produced in the same process as in Example 1 except that the amount of the inorganic pigment added was outside the range of the present embodiment, or the inorganic pigment was added to the upper adhesive layer.

(5-5. Comparative Examples 11 and 12)
Except that the softening temperature of the upper layer adhesive was higher than the softening temperature of the lower layer adhesive, a design metal plate was produced in the same process as in Example 1.

(5-6. Comparative Example 13)
A design metal plate was produced in the same process as in Example 1 except that the softening temperature of the upper layer adhesive was higher than 80 ° C.

(5-7. Comparative Example 14)
Except that the softening temperature of the lower layer adhesive was set to less than 90 ° C., a design metal plate was produced in the same process as in Example 1. Tables 8 to 19 collectively show the configurations of the design metal plates manufactured in the respective examples and comparative examples.

<6. Evaluation of design metal sheets>
(6-1. Initial adhesion)
The initial adhesion was evaluated using a monocolor embossed plate. Specifically, a # -shaped notch having a width of 5 mm was formed in the monocolor embossed film with a cutter knife. Here, the depth of the cut was set to such a depth as to reach the metal plate. Then, the # -type cut portion was protruded by 8 mm using an Erichsen tester (manufactured by DKSH, Erichsen tester). Here, the center of the overhanging portion (top portion) was made to coincide with the center of the # -shaped notch portion. Then, the # -cut portion was forcibly peeled off with tweezers, and the degree of peeling was evaluated according to the following criteria.
◎◎: Score 5 (the film was cohesively broken and hardly peeled off)
：: Rating 4 (only the top part was peeled)
：: Rating 3 (less than 1/3 of the entire top and side surfaces peeled)
×: Score 2 (the entire top part and the entire side part are peeled off)
XX: Score 1 (the whole top part, the whole side surface processed part, and the periphery of the # -shaped cut part are peeled off)
Then, the same test was repeated five times. The results are summarized in Tables 8 to 19. In addition, when there was a variation in the evaluation for each test, the upper and lower limits of the evaluation were described in the table.

(6-2. Emboss return rate)
Using a single-color embossed plate, the emboss return ratio, which is one of the evaluation indexes of the initial design retention, was evaluated. Specifically, the arithmetic average roughness Ra1 of the monochromatic embossed film surface and the arithmetic average roughness Ra2 of the monochromatic embossed plate surface (specifically, the surface of the monochromatic embossed film attached to the monochromatic 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. Next, the emboss return ratio, which is one of the indexes of the initial design retention, was calculated by the following equation (2). The results are summarized in Tables 8 to 19.
Emboss return rate χ: χ = 1−Ra2 / Ra1 (2)

(6-3. Sharpness and discoloration)
Using a high-definition film, the sharpness (PDG value) and discoloration, which are one of the evaluation indexes of the initial design retention, were evaluated. Specifically, the sharpness of the surface of the high-definition film and the surface of the high-definition plate (specifically, the surface of the high-definition film attached to the surface of the high-definition plate) is measured by a sharpness gloss meter. (PGD-IV manufactured by Japan Color Research Institute). Then, the sharpness was evaluated according to the following criteria.
◎: Difference in sharpness between high definition film and high definition plate is less than 0.1 ○: Difference in definition between high definition film and high definition plate is 0.1 to 0.2
X: The difference in sharpness between the high definition film and the high definition plate was 0.3 or more. The same test was repeated five times. The results are summarized in Tables 8 to 19. In addition, when there was a variation in the evaluation for each test, the upper and lower limits of the evaluation were described in the table.

Furthermore, the a value of the surface of the high definition film and the surface of the high definition plate was measured by a color difference meter (CM-2600d manufactured by Konica Minolta). Here, the a value is a value for evaluating redness. Since redness is particularly likely to disappear during the production of a design metal plate, the color loss was evaluated using the a value. Then, the difference a between the a-values (= a-value of the high-definition film-a-value of the high-definition film) was calculated, and the color loss was evaluated based on the following criteria.
◎: Δa <3.0
：: 3.0 <Δa <5.0
×: Δa> 5.0
Then, the same test was repeated five times. The results are summarized in Tables 8 to 19. In addition, when there was a variation in the evaluation for each test, the upper and lower limits of the evaluation were described in the table.

(6-4. Durability)
The durability was evaluated using a single-color embossed plate. Specifically, the monocolor embossed plate was immersed in boiling water and 75 ° C. warm water for 20 days. When the softening temperature of the lower adhesive was lower than 100 ° C., except for Example 6 and some comparative examples, it was immersed only in hot water of 75 ° C. Hereinafter, such a test is also referred to as an “immersion test”. Next, the film adhesion after the immersion test was evaluated by the same test as the initial adhesion described above. Furthermore, the end of the monocolor embossed plate after the immersion test was visually observed to evaluate whether the monocolor embossed film had returned (peeled) or corroded. The presence or absence of corrosion was determined only for metal plates having a problem of corrosion, that is, GI steel plates and SD steel plates. Then, the same test was repeated five times. The results are summarized in Tables 8 to 19. In addition, when there was a variation in the evaluation for each test, the upper and lower limits of the evaluation were described in the table.

(6-5. Evaluation of concealability)
Cut monochromatic embossing plate 50 × 50 mm, the L value of any 5 points were measured with a color difference meter as described above, to give the arithmetic mean value L _a. As a standard sample, PES-1 and PES-5-R1 each having a thickness of 2 μm were used for the adhesive side and the metal plate side layer, respectively, and a single-color embossed film was formed by laminating a single-color embossed film having a thickness of 100 μm. And determine the standard sample _{L a,} which was used as a _{L as.} The concealability was calculated by the following equation and evaluated as follows. The results are summarized in Tables 8 to 19.
Concealing _{property: L a / L as × 100} (%)
_{◎◎◎: L a / L as>} 99.9
_◎◎: L _a / L as 99.5~99.9
_{◎: L a / L as =} 98.0~99.5
_{○: L a / L as =} 96.5~98.0
_{×: L a / L as <} 96.5

<7. Consideration of evaluation results>
(7-1. Consideration on adhesive)
In Examples 1 to 37, high evaluations were obtained for all of the initial adhesion, the initial design retention, and the durability. That is, regardless of whether the metal plate is aluminum, copper, titanium, or a steel plate, a high adhesion force can be exhibited at the initial stage and after immersion in boiling water while maintaining the initial design.

  In Examples 1 to 37, 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 sufficiently To the metal plate. Accordingly, both the initial adhesion and the initial design retention were increased. Further, since the softening temperature of the lower adhesive is 90 ° C. or higher, even if the design metal plate is exposed for a long time in a high-temperature and high-humidity environment, water molecules may reach the interface between the metal plate and the lower adhesive layer. Intrusion can be prevented. Therefore, the durability was improved.

  Furthermore, in Example 1, the softening temperature of the upper layer adhesive is higher than 70 ° C., but in Examples 2 to 11, the softening temperature of the upper layer adhesive is 70 ° C. or lower. And the initial design retention of Examples 2 to 11 was superior to the initial design retention of Example 1. In Examples 2 to 11, since the softening temperature of the upper layer side adhesive is 70 ° C or lower, 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 4-1 to 4-12 and 6, it was found that the initial design retention was further improved by setting the upper layer heating temperature to 140 ° C. or lower.

  Further, when the softening temperature of the lower adhesive was 100 ° C. or more, even under extremely severe high-temperature and high-humidity conditions of immersion in boiling water, it was possible to maintain strong adhesion including the end portions. That is, extremely high durability could be obtained.

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

  Furthermore, when Example 7 was compared with Examples 1 to 6, in Example 7, the durability was higher. Similarly, when comparing Example 15 with Examples 12 to 14, in Example 15, the durability was higher. In Examples 7 and 15, 2 to 15 parts by mass of the silane coupling agent was added to the lower adhesive composition based on 100 parts by mass of the lower adhesive. For this reason, in Examples 7 and 15, the adhesion between the metal plate and the lower adhesive layer is further enhanced. Therefore, even under extremely severe high-temperature and high-humidity conditions, it was possible to maintain strong adhesion including the end portions.

  On the other hand, in Comparative Examples 1 and 2, the adhesive layer was a single layer, and the softening temperature of the adhesive was 80 ° C. or less. Therefore, even when the heating temperature was low (180 ° C. or less), the design film could be sufficiently adhered to the metal plate. However, the adhesion decreased significantly after the immersion test. This is because 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 into the interface between the metal plate and the lower-side adhesive layer from the end of the design metal plate during the immersion test, and the adhesion was reduced by the water molecules. . Therefore, in Comparative Examples 1 and 2, other durability tests were not performed. In addition, when the design film can be adhered to the metal plate at a low temperature, the initial design retention is also increased. Therefore, the test for the initial design retention was not performed.

  In Comparative Examples 3 and 4, the adhesive layer was a single layer, and the softening temperature of the adhesive was 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, even when the heating temperature was higher than 180 ° C., the design film and the metal plate could not be sufficiently adhered. This is considered to be due to poor affinity between the plasticizer contained in the design film and the adhesive layer.

  In Comparative Examples 11 to 12, the same adhesive as that of the example was used, but the softening temperature of the upper adhesive and the softening temperature of the lower adhesive were reversed. That is, in Comparative Examples 11 to 12, since the softening temperature of the upper-layer-side adhesive is 90 ° C. or higher, the design film is sufficiently adhered to the metal plate unless the upper-layer heating temperature is increased (greater than 180 ° C.). I couldn't do that. As a result, the initial design retention was significantly reduced. Furthermore, corrosion occurred at the end of the design metal plate by the immersion test. Since the softening temperature of the lower adhesive is 80 ° C. or less, water molecules intrude into the interface between the metal plate and the lower adhesive layer from the end of the design metal plate during the immersion test, and the water plate causes Probably corroded. In Comparative Examples 11 to 12, the film peeling was not evaluated because corrosion occurred at the end.

  In Comparative Example 13, the softening temperature of the lower adhesive was higher than the softening temperature of the upper adhesive. However, since the softening temperature of the upper layer adhesive is higher than 80 ° C., the design film cannot be sufficiently adhered to the metal plate unless the upper layer heating temperature is higher (greater than 180 ° C.). As a result, the initial design retention was significantly reduced.

  In Comparative Example 14, the softening temperature of the lower adhesive was higher than the softening temperature of the upper adhesive, but the softening temperature of the upper adhesive was 80 ° C. or lower. Therefore, even when the heating temperature was low (180 ° C. or less), the design film could be sufficiently adhered to the metal plate. However, the softening temperature of the lower adhesive is lower than 90 ° C. Then, the adhesion strength was significantly reduced by the immersion test. Since the softening temperature of the lower adhesive is lower than 90 ° C., it is considered that water molecules penetrated into the interface between the metal plate and the lower adhesive layer during the immersion test, and the water molecules reduced the adhesion.

(7-2. Consideration on inorganic pigment)
In Examples 1 to 37, even when the thickness of the design film was less than 100 μm, it was possible to maintain the same degree of concealment as when the thickness of the design film was 100 μm. Furthermore, as shown in Examples 4-8 and 4-12, the concealing property was able to be ensured even when the thickness of the design film fluctuated greatly.

  On the other hand, in Comparative Examples 1 and 2, the adhesive layer was a single layer, and the initial adhesion was secured. However, the durability was extremely poor. Therefore, in Comparative Examples 1 and 2, the evaluation of the concealing property was not performed. In Comparative Examples 3 and 4, the adhesive layer was a single layer, and the initial adhesion could not be secured. Therefore, in Comparative Examples 3 and 4, the evaluation of the concealing property was not performed.

  In Comparative Examples 5 to 10, the structure of the adhesive layer is the same as that of the example. However, as shown in Comparative Examples 5 and 6, when the amount of the inorganic pigment added to the lower adhesive layer was less than 3 parts by mass, sufficient hiding power could not be exhibited. When the amount of the inorganic pigment added exceeded 50 parts by mass as in Comparative Example 7, the adhesive composition was thickened and could not be uniformly applied. Furthermore, as shown in Comparative Examples 8 to 10, when an inorganic pigment was added to the upper adhesive layer in contact with the design film, the initial adhesion could not be exhibited. Hereinafter, the examples will be considered in more detail.

(7-2-1. Particle size of inorganic pigment)
Examples 4-5, 4-6, and 4-7 were inferior in concealing properties as compared with the other examples. In each case, the particle size of the added inorganic pigment is more than 0.3 μm. Further, this tendency became stronger as the particle size became larger. It is considered that the concealing property decreased because the scattering cross section decreased as the particle size increased. Further, in Example 4-7 in which an inorganic pigment having a particle size of more than 1 μm was added, the adhesive layer was cohesively broken and the initial adhesion was slightly inferior. It is considered that such a phenomenon occurred when the particle size became large, because stress was easily concentrated on the interface between the lower layer adhesive and the inorganic pigment. From the above, it is desirable that the average particle size of the inorganic pigment to be added is 1 μm or less. The average particle size of the inorganic pigment is more preferably from 0.2 to 0.4 μm, more preferably from 0.2 μm to less than 0.4 μm, and further preferably from 0.2 to 0.3 μm.

(7-2-2. Effect of organic treatment)
In Example 4-4 and Example 4-3, the amount of the inorganic pigment added and the average particle size were the same. Nevertheless, Example 4-3 was more excellent in hiding. The inorganic pigment of Example 4-3 has been organically treated. For this reason, it is considered that the particles were more uniformly dispersed in the lower adhesive layer, and the scattering cross section increased.

(7-2-3. Addition amount of inorganic pigment)
According to Examples 4-9 and 4-10, the concealing property increased as the amount of the inorganic pigment added increased. However, in Example 4-13 in which the addition amount of the inorganic pigment was 50 parts by mass, the mechanical strength of the adhesive layer was slightly deteriorated. The cause is presumed to be the same as in Example 4-7. From this result, the addition amount of the inorganic pigment is preferably 25 to 50 parts by mass, more preferably 25 parts by mass or more and less than 50 parts by mass, and more preferably 30 to 45 parts by mass.

  As described above, the preferred embodiments of the present invention have been described in detail with reference to the accompanying drawings, but the present invention is not limited to such examples. It is obvious that those skilled in the art to which the present invention pertains can conceive various changes or modifications within the scope of the technical idea described in the claims. It is understood that these also belong to the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 10 Design metal plate 20 Steel plate 30 Design film 40 Adhesive layer 41 Lower layer adhesive layer 42 Upper layer adhesive layer 100, 101 Design metal plate manufacturing apparatus 120 1st roll coater 130 1st oven 140 2nd roll coater 150 2nd oven 160 Design film transport device 170 Cooling device

Claims (28)

A metal plate,
A lower adhesive layer laminated on the metal plate,
An upper adhesive layer laminated on the lower adhesive layer,
And a design film laminated on the upper adhesive layer,
The lower adhesive layer includes a lower adhesive and an inorganic pigment,
The upper adhesive layer includes an upper adhesive,
The softening temperature of the upper layer side adhesive is 80 ° C. or less,
The softening temperature of the lower adhesive is 90 ° C. or higher,
The design metal plate, wherein the lower adhesive layer contains 3 to 50 parts by mass of the inorganic pigment based on 100 parts by mass of the lower adhesive.   The design metal plate according to claim 1, wherein the lower adhesive layer includes 25 to 50 parts by mass of the inorganic pigment based on 100 parts by mass of the lower adhesive.   The design metal plate according to claim 1, wherein an average particle size of the inorganic pigment is 1 μm or less.   The design metal plate according to claim 3, wherein the inorganic pigment has an average particle size of 0.2 to 0.4 m.   The design metal plate according to any one of claims 1 to 4, wherein a softening temperature of the upper layer-side adhesive is 70 ° C or less.   The design metal plate according to any one of claims 1 to 5, wherein a softening temperature of the lower layer-side adhesive is 100 ° C or more.   The lower layer-side adhesive and the upper layer-side adhesive are made of at least one of polyester-based, acrylic-based, urethane-based, epoxy-based, and urea-based thermosetting adhesives. The design metal plate according to any one of claims 1 to 6.   The lower layer-side adhesive and the upper layer-side adhesive are polyester-based resins obtained by adding 3 to 25 parts by mass of a polyisocyanate resin having an isocyanate group of 30 mol% or more based on all dicarboxylic acid residues to 100 parts by mass of a linear polyester resin. The design metal plate according to any one of claims 1 to 7, which is a thermosetting adhesive.   The design metal according to any one of claims 1 to 8, wherein the lower adhesive layer contains 2 to 15 parts by mass of a silane coupling agent with respect to 100 parts by mass of the lower adhesive. Board.   The design film according to any one of claims 1 to 9, wherein the design film is formed of at least one of a vinyl chloride resin, a polyester resin, an acrylic resin, a polyolefin resin, and a fluororesin. The described design metal plate.   The design metal plate according to claim 10, wherein the design film is made of a vinyl chloride resin.   The design metal plate according to any one of claims 1 to 11, wherein a softening temperature of a portion of the design film that is in contact with the upper-side adhesive layer is lower than 150 ° C. It is a manufacturing method of the design metal plate which manufactures the design metal plate according to any one of claims 1 to 12,
A method for producing a design metal plate, comprising: bonding the metal plate at 180 ° C. or lower to the design film via the lower adhesive layer and the upper adhesive layer. By laminating a lower adhesive and an inorganic pigment on a metal plate, a step of forming a lower adhesive layer on the metal plate,
By heating the metal plate, a step of bringing the lower adhesive layer into close contact with the metal plate,
By laminating an upper adhesive on the lower adhesive layer, a step of forming an upper adhesive layer on the lower adhesive layer,
Heating the metal plate to a heating temperature of 180 ° C. or lower to soften the upper layer adhesive;
Laminating a design film on the upper adhesive layer,
The softening temperature of the upper layer side adhesive is 80 ° C. or less,
The softening temperature of the lower adhesive is 90 ° C. or higher,
The method for producing a design metal plate, wherein the lower adhesive layer contains 3 to 50 parts by mass of the inorganic pigment based on 100 parts by mass of the lower adhesive. By laminating a lower adhesive and an inorganic pigment on a metal plate, a step of forming a lower adhesive layer on the metal plate,
By heating the metal plate, a step of bringing the lower adhesive layer into close contact with the metal plate,
A step of preparing a laminated film in which the upper adhesive layer including the upper adhesive is laminated on the design film,
Bonding the lower adhesive layer on the metal plate and the upper adhesive layer on the design film in a state where the temperature of the metal plate is 180 ° C. or less,
The softening temperature of the upper layer side adhesive is 80 ° C. or less,
The softening temperature of the lower adhesive is 90 ° C. or higher,
The method for producing a design metal plate, wherein the lower adhesive layer contains 3 to 50 parts by mass of the inorganic pigment based on 100 parts by mass of the lower adhesive. The step of preparing the laminated film,
By laminating the upper layer adhesive on the design film, a step of forming an upper layer adhesive layer on the design film,
The method for manufacturing a design metal plate according to claim 15, further comprising: a step of heating the design film to bring the upper adhesive layer into close contact with the design film. By laminating the lower adhesive, the lower adhesive composition containing the inorganic pigment and the solvent on the metal plate, to form the lower adhesive layer,
The method according to any one of claims 14 to 16, wherein, by heating the metal plate, the solvent contained in the lower adhesive layer is evaporated, and the lower adhesive layer is adhered to the metal plate. 2. The method for producing a design metal sheet according to claim 1.   The design metal plate according to any one of claims 14 to 16, wherein the lower metal layer is adhered to the metal plate by heating the metal plate to a heating temperature of more than 180 ° C. Manufacturing method.   The method for manufacturing a design metal sheet according to any one of claims 14 to 18, wherein the softening temperature of the upper layer adhesive is 70C or lower.   The method according to any one of claims 14 to 19, wherein a softening temperature of the lower adhesive is 100C or more.   The lower layer-side adhesive and the upper layer-side adhesive are made of at least one of polyester-based, acrylic-based, urethane-based, epoxy-based, and urea-based thermosetting adhesives. The method for producing a design metal sheet according to any one of claims 14 to 20.   The lower layer-side adhesive and the upper layer-side adhesive are polyester-based resins obtained by adding 3 to 25 parts by mass of a polyisocyanate resin having an isocyanate group of 30 mol% or more based on all dicarboxylic acid residues to 100 parts by mass of a linear polyester resin. The method for producing a design metal sheet according to any one of claims 14 to 21, wherein the method is a thermosetting adhesive. By laminating the lower adhesive composition containing the lower adhesive, the inorganic pigment and the silane coupling agent on the metal plate, the lower adhesive layer is formed,
The said silane coupling agent is contained in the said lower adhesive composition in the ratio of 2-15 mass parts with respect to 100 mass parts of said lower adhesives, The any one of Claims 14-22 characterized by the above-mentioned. 2. The method for producing a design metal sheet according to claim 1.   24. The design film according to claim 14, wherein the design film is formed of at least one of a vinyl chloride resin, a polyester resin, an acrylic resin, a polyolefin resin, and a fluororesin. The method for producing the design metal plate described in the above.   The method according to claim 24, wherein the design film is made of a vinyl chloride resin.   The method for manufacturing a design metal plate according to any one of claims 14 to 25, wherein a softening temperature of a portion of the design film that is in contact with the upper adhesive layer is lower than 150 ° C. A metal plate, a multilayer adhesive for a design metal plate for bonding a design film,
The multilayer adhesive for a design metal plate includes an upper adhesive layer in contact with the design film, and a lower adhesive layer in contact with the metal plate,
The lower adhesive layer includes a lower adhesive and an inorganic pigment,
The upper adhesive layer includes an upper adhesive,
The softening temperature of the upper layer side adhesive is 80 ° C. or less,
The softening temperature of the lower adhesive is 90 ° C. or higher,
The multilayer adhesive for a design metal plate, wherein the lower adhesive layer contains 3 to 50 parts by mass of the inorganic pigment based on 100 parts by mass of the lower adhesive. Metal plate, of the multilayer adhesive for design metal plate to adhere the design film, the lower adhesive layer composition constituting the lower adhesive layer in contact with the metal plate,
The lower layer-side adhesive layer composition includes a lower layer-side adhesive and an inorganic pigment,
The softening temperature of the lower adhesive is 90 ° C. or higher,
The composition for the lower adhesive layer, wherein the composition for the lower adhesive layer contains 3 to 50 parts by mass of the inorganic pigment based on 100 parts by mass of the lower adhesive.

Images