Graphic sheet, graphic sheet with protective film, method for manufacturing the same and method for using the same

Abstract

To provide a graphic sheet which prevents peeling of a printed layer, maintains image quality over a long period of time and has high durability, even if an image is formed by inkjet printing, a graphic sheet with a protective film, a method for manufacturing the same, and a method for using the same.SOLUTION: A graphic sheet 1 includes a surface resin layer 2, an ink receiving layer 3, a printed layer 4, an ink substrate layer 5, and an adhesive layer 6 in this order, wherein the printed layer 4 is an inkjet printed layer, when the printed layer 4 is cut at an angle of 45° from the side of the surface resin layer 2, and peel off test is performed thereon, the printed layer 4 is not peeled or the printed layer 4 is subjected to cohesion breakage. There is provided a graphic sheet 10 with a protective film, wherein a protective film 7 is stuck to the outer surface of the surface resin layer 2, and a release film 8 is stuck to the outer surface of the adhesive layer 6.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a graphic sheet containing a printing layer, a graphic sheet with a protective film, a method for manufacturing the same, and a method for using the same.

Background Art

[0002] Japanese automobile number plates generally form convex portions having shapes such as place names and numbers on an aluminum plate coated with white paint by embossing, and print a coloring layer using ink such as green on the convex portions. In other countries, there are examples where number plates using graphic sheets, retroreflective sheets, etc. in addition to vehicle identifiability are used, and in recent years, such products have also started to be used in Japan. Such number plates are formed by laminating a graphic sheet, a retroreflective sheet, etc. on a base plate.

[0003] Patent Document 1 proposes a graphic film for a license plate with high whiteness, and it is proposed to suppress the occurrence of defects such as film breakage and peeling during embossing and over time. Further, the applicant of the present application has proposed in Patent Document 2 a graphic sheet that includes a surface resin layer, a printing layer on the back side of the surface resin layer, an ink underlayer, and an adhesive layer in this order from the viewing side. The surface resin layer is a polycarbonate-based urethane resin. In particular, the ink underlayer uses an alkyd melamine-based resin, has good embossing processability, weather resistance, and adhesion to the ink layer, and further does not require an after-clear coat or over-lamination. Even after being attached to a base material such as a base plate for a number plate, it is difficult to peel off without damage and has high security. Further, the applicant of the present application has proposed in Patent Document 3 a graphic sheet that solves the yellowing problem.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

[0005] However, when forming an image by inkjet printing, the conventional technology had a problem that the printed layer peeled off depending on a specific color and density. When the printed layer peeled off, it bulged, the image was damaged, and the quality deteriorated, and the license plate could not be used for a long period of time.

[0006] In order to solve the above conventional problems, the present invention provides a highly durable graphic sheet, a graphic sheet with a protective film, a method for manufacturing the same, and a method for using the same, in which the printed layer does not peel off even when an image is formed by inkjet printing, the image quality can be maintained for a long period of time. [Means for Solving the Problems]

[0007] The present invention includes a surface resin layer, an ink receiving layer, a printed layer, an ink underlayer, and an adhesive layer in this order, the printed layer is an inkjet printed layer, and when cut at an angle of 45° from the surface resin layer side and subjected to a peel-off test, the printed layer does not peel off or the printed layer undergoes cohesive failure. It is a graphic sheet.

[0008] In the graphic sheet with a protective film of the present invention, a protective film is attached to the outer surface of the surface resin layer, and a release film is attached to the outer surface of the adhesive layer.

[0009] The method for manufacturing the graphic sheet with a protective film of the present invention is as follows. Step A: A surface resin layer is formed on the surface of a base film for the process by a casting method. Step B: An ink receiving layer is formed on the surface of the surface resin layer by a casting method. C A printing layer is formed on the surface of the ink receiving layer by inkjet printing, D An ink underlayer is formed on the surfaces of the ink receiving layer and the printing layer by a casting method, E An adhesive layer is formed on the surface of a separately prepared release film by a casting method, F The adhesive layer is bonded to the surface of the ink underlayer, G A method for manufacturing a graphic sheet with a protective film, which includes a step of peeling off the base material film for the process and laminating a protective film on the surface resin layer.

[0010] The method of using the graphic sheet with a protective film of the present invention is to bond the graphic sheet with a protective film on a base plate, create a symbol by embossing or debossing, peel off the protective film, and then place a symbol ink layer on the symbol and bake it to obtain a number plate with the graphic sheet attached.

Advantages of the Invention

[0011] The graphic sheet of the present invention includes a surface resin layer, an ink receiving layer, a printing layer, an ink underlayer, and an adhesive layer in this order. The printing layer is an inkjet printing layer. When cut at an angle of 45° from the surface resin layer side and subjected to a peel-off test, the printing layer does not peel off or the printing layer undergoes cohesive failure. By making it such a graphic sheet, a graphic sheet with high durability can be provided, in which the printing layer does not peel off and the image quality can be maintained for a long time, as well as a graphic sheet with a protective film, a method for manufacturing the same, and a method for using the same. That is, by disposing the ink receiving layer on the surface resin layer and disposing the printing layer thereon, the printing layer is firmly adhered to the ink receiving layer so that the printing layer does not peel off or the printing layer undergoes cohesive failure. As a result, a graphic sheet with high durability and capable of maintaining the image quality for a long time can be obtained.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0013] The present inventors examined why the inkjet printing layer peels off in the conventional example. As a result, when the ink underlayer is an alkyd melamine layer, there is almost no problem with cyan and yellow at a setting density of 10 - 100% of the inkjet printer, but there is floating or peeling at 40 - 100% with magenta and 20 - 100% with orange. Also, when the ink underlayer is an alkyd isocyanate, there is almost no problem with cyan at a setting density of 10 - 100% of the inkjet printer, but there is floating or peeling at 60 - 100% with magenta, 70 - 100% with yellow, and 30 - 100% with orange. That is, it was found that floating or peeling is likely to occur in the case of magenta-based and orange-based colors with high concentrations. Therefore, the present invention was completed by conceiving to dispose an ink receiving layer having good adhesion to the inkjet printing layer on the surface resin layer and disposing a printing layer thereon.

[0014] The present invention includes a surface resin layer, an ink receiving layer, a printing layer, an ink underlayer, and an adhesive layer in this order as viewed from the visual recognition direction (EY). Since the printing layer is encapsulated by the surface resin layer, the ink receiving layer, and the ink underlayer, it will not be damaged. The printing layer is visible from the outside through the surface resin layer. And the printing layer and the ink receiving layer are firmly adhered to the ink receiving layer so that they do not peel off even in a peel-off test or the printing layer undergoes cohesive failure. As a result, the image quality can be maintained for a long time, and a highly durable graphic sheet can be obtained. In the present invention, in the peel-off test, first, a cutter is inserted at an angle of 45° from the surface resin layer side and cut. Usually, the cutter is inserted at an angle of 90°, but it is set at 45° to create more severe conditions. Next, an adhesive tape is attached to the cut portion from above the surface resin layer in a direction perpendicular to the cut portion and peeled off. Whether it is cohesive failure or interfacial failure is determined by observing with an optical microscope.

[0015] For the printing layer, it is preferable to use an inkjet printer to inject ink in a dot shape from a nozzle and color the subject in the form of dots when the coloring density is low. In this state, the peeling problem of the printing layer is less likely to occur. However, when the coloring density becomes high, the ink ejected from the nozzle forms a continuous film, and the peeling problem of the printing layer is likely to occur. Therefore, when the ratio of the colored ink portion per unit area is 50% or more, the effect of the present invention becomes higher.

[0016] The ink receiving layer is preferably a copolymer or a multi-component copolymer resin containing a vinyl group, and / or a resin containing a urethane bond, or a mixture thereof. More specifically, the ink receiving layer is preferably a vinyl chloride-vinyl acetate-vinyl alcohol resin, a vinyl chloride-vinyl acetate-hydroxyacrylate resin, a vinyl chloride-vinyl acetate resin, a vinyl acetate resin, a styrene-acrylic resin, a polyvinyl butyral resin, a polyester-based polyurethane resin, or a polyether-based polyurethane resin. Thereby, the affinity with the printing layer is increased, and peeling of the printing layer is less likely to occur.

[0017] The thickness of the ink receiving layer is preferably 0.1 to 30 μm, more preferably 0.5 to 28 μm, and even more preferably 1 to 25 μm. With such thickness, the overall thickness can be reduced, which is suitable for automobile number plates and the like.

[0018] Additives such as leveling agents, ultraviolet absorbers, plasticizers, and curing agents may be added to the ink receiving layer.

[0019] As the leveling agent, acrylic, silicone, fluorine, and acetylene glycol types are preferred. Examples of acrylic type include "Polyflow No. 85" manufactured by Kyoeisha Chemical Co., Ltd. Examples of silicone leveling agents include "Polyflow KL-100" manufactured by Kyoeisha Chemical Co., Ltd. Examples of fluorine leveling agents include the "Surflon" series manufactured by AGC Seimi Chemical Co., Ltd. Examples of acetylene glycol type include the "Orfin" series manufactured by Nissin Chemical Industry Co., Ltd.

[0020] As the ultraviolet absorber, benzotriazole, benzoate, benzoxazinone, benzophenone, and triazine types are preferred. Examples of benzotriazole type include "Tinuvin 900" manufactured by BASF. Examples of benzoate type include "Tinuvin 120" manufactured by BASF. Examples of benzoxazinone type include "DXSORB 3638" manufactured by Danshiajapan Co., Ltd. Examples of benzophenone type include "Disizer E" manufactured by Sankyo Kasei Co., Ltd. Examples of triazine type include "DXSORB 400" manufactured by Danshiajapan Co., Ltd.

[0021] As the plasticizer, phthalate, adipate, polyester, phosphate, and epoxidized vegetable oil types are preferred. Examples of phthalate type include "DUP" manufactured by Mitsubishi Chemical Corporation. Examples of adipate type include "DOA" manufactured by Mitsubishi Chemical Corporation. Examples of polyester type include the "Polysizer" series manufactured by DIC Corporation. Examples of phosphate type include "P0273" manufactured by Tokyo Chemical Industry Co., Ltd. Examples of epoxidized vegetable oil type include the "Adekasizer" series manufactured by ADEKA Corporation.

[0022] As the hardener, epoxy-based, melamine-based, isocyanate-based, oxazoline-based, and carbodiimide-based ones are preferred. Examples of epoxy-based ones include "TETRAD-C" manufactured by Mitsubishi Gas Chemical Company. Examples of melamine-based ones include the "Amidia" series manufactured by DIC Corporation. Examples of isocyanate-based ones include the "Barnock" series with the trade name manufactured by DIC Corporation. Examples of oxazoline-based ones include the "Epocross" series manufactured by Nippon Shokubai Co., Ltd. Examples of carbodiimide-based ones include the "Carbodilite" series manufactured by Nisshinbo Chemicals, Inc.

[0023] The surface resin layer preferably contains at least one resin selected from urethane resin, alkyd resin, acrylic resin, and vinyl chloride resin.

[0024] Hereinafter, each resin will be described. <Ink-receiving layer> The ink-receiving layer preferably contains vinyl chloride-vinyl acetate-vinyl alcohol resin, vinyl chloride-vinyl acetate-hydroxyacrylate resin, vinyl chloride-vinyl acetate resin, or polyester-based polyurethane resin. Examples of vinyl chloride-vinyl acetate-vinyl alcohol resin, vinyl chloride-vinyl acetate-hydroxyacrylate resin, and vinyl chloride-vinyl acetate resin include "Solvain" with the trade name manufactured by Nissin Chemical Co., Ltd. Examples of polyester-based polyurethane resin include "Hydran" with the trade name manufactured by DIC Corporation and "Resamin" with the trade name manufactured by Dainichi Seika Kogyo Co., Ltd.

[0025] <Ink underlayer> The ink underlayer is an alkyd resin, and a resin cured with a curing agent that does not contain a melamine component can be used. As the curing agent, at least one selected from isocyanate-based curing agents, epoxy-based curing agents, oxazoline-based curing agents, carbodiimide-based curing agents, and aziridine-based curing agents is preferable. Thereby, yellowing of the graphic sheet can be prevented by high-temperature baking. The resins obtained by curing an alkyd resin with an isocyanate-based curing agent, an epoxy-based curing agent, an oxazoline-based curing agent, a carbodiimide-based curing agent, and an aziridine-based curing agent are alkyd isocyanate-based resins, alkyd epoxy-based resins, alkyd oxazoline-based resins, alkyd carbodiimide-based resins, and alkyd aziridine-based resins, respectively.

[0026] The ink underlayer may use an alkyd melamine resin. The alkyd melamine resin is a mixture of an alkyd resin and a melamine resin as a cured resin component. The alkyd resin is a synthetic resin made by polycondensation of a polybasic acid or fatty acid (or fatty oil) and polyhydric alcohols. Examples of polybasic acids include phthalic acid, phthalic anhydride, isophthalic acid, terephthalic acid, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, trimellitic acid, trimellitic anhydride, pyromellitic acid, succinic acid, adipic acid, sebacic acid, benzoic acid, etc. Examples of fatty acids include soybean oil, coconut oil, linseed oil, castor oil, dehydrated castor oil, safflower oil, tall oil, palm kernel oil, etc. Examples of polyhydric alcohols include ethylene glycol, propylene glycol, 1,3-butylene glycol, 1,6-hexanediol, trimethylolethane, trimethylolpropane, glycerin, etc. The alkyd resin composed of the above raw materials may be modified with resins such as acrylic, urethane, epoxy, phenol, and silicon. Examples of commercially available products include the "Bekkolite" series manufactured by DIC Corporation and the "Amilac" series manufactured by Kansai Paint Co., Ltd. The melamine resin used as the cured resin component is generally a resin obtained by adding and condensing melamine and formaldehyde and etherifying with an aliphatic monohydric alcohol (methanol or butanol). Examples of commercially available products include the "Super Bekamin" series manufactured by DIC Corporation. Alkyd melamine resins are widely used in the automotive paint industry and are preferred because they have a proven track record of being used on ordinary license plates overseas. Furthermore, they are excellent in terms of processability, especially low-temperature embossing properties at 1 to 5°C. The ink underlayer is preferably a resin containing a transparent resin or a white pigment. When colored white, it has high hiding power and the substrate cannot be seen even when thin. The addition amount of the whitening agent is preferably 1 to 50 parts by weight, more preferably 5 to 30 parts by weight, and even more preferably 5 to 10 parts by weight with respect to 100 parts by weight of the ink underlayer or the adhesive layer.

[0027] The isocyanate-based curing agent refers to polyisocyanate and is a compound containing two or more isocyanate groups in one molecule. Examples of polyisocyanates include aliphatic polyisocyanates such as methylene diisocyanate, hexamethylene diisocyanate, and trimethylhexamethylene diisocyanate; alicyclic polyisocyanates such as cyclohexane diisocyanate and isophorone diisocyanate; aromatic polyisocyanates such as toluene diisocyanate and methylene bisphenyl diisocyanate; adducts, biurets, and isocyanurates of the above polyisocyanates; blocked isocyanates in which the isocyanate groups of the above polyisocyanates are protected with a blocking agent; and modified products of the above polyisocyanates. Examples of the modified products of the polyisocyanates include polyisocyanate modified products in which the isocyanate compound is modified by an allophanate bond, a urea bond, a uretdione bond, etc. As the isocyanate-based curing agent, aliphatic and alicyclic polyisocyanates are preferred in terms of excellent heat-resistant yellowing and weather resistance. Examples of commercially available isocyanate-based curing agents include the "Barnoak" series manufactured by DIC Corporation, the "Coronate" series manufactured by Tosoh Corporation, and the "Duronate" series manufactured by Asahi Kasei Corporation.

[0028] The epoxy curing agent refers to an epoxy resin, which is a compound containing two or more epoxy groups in one molecule. Examples of epoxy resins include aliphatic epoxy resins such as glycidyl ether compounds of aliphatic polyhydric alcohols like ethylene glycol, glycerin, trimethylolpropane, polyethylene glycol, and glycidyl ester compounds of aliphatic polycarboxylic acids like malonic acid, succinic acid, adipic acid, 1,2,3,4-butanetetracarboxylic acid. Alicyclic epoxy resins such as bis(2,3-epoxycyclopentyl) ether, 3,4-epoxycyclohexylmethyl, 3’,4’-epoxycyclohexanecarboxylate, bis(3,4-epoxycyclohexylmethyl) adipate, limonene dioxide, etc., and aromatic epoxy resins such as glycidyl ether compounds of aromatic polyhydric alcohols like bisphenol A, bisphenol F, bisphenol AD, novolac, and glycidyl ester compounds of aromatic polycarboxylic acids like phthalic acid, 1,4-naphthalenedicarboxylic acid, trimellitic acid, pyromellitic acid, etc. Among them, aliphatic and alicyclic epoxy resins are preferred as the epoxy curing agent in terms of excellent heat resistance yellowing resistance, weather resistance, etc. Commercially available epoxy curing agents include the "Epiclon" series manufactured by DIC Corporation, the "TETRAD" series manufactured by Mitsubishi Gas Chemical Company, the "Adekarezine EP" series manufactured by ADEKA Corporation, etc.

[0029] The oxazoline curing agent is a compound containing two or more oxazoline groups in one molecule. Examples of oxazoline curing agents include polyvalent oxazolines such as 2,2’-bis-(2-oxazoline), 2,2’-methylene-bis-(2-oxazoline), 2,2’-(1,4-phenylene)-bis(2-oxazoline), and copolymers composed of oxazoline group-containing monomers such as 2-vinyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2-isopropenyl-5-ethyl-2-oxazoline. The oxazoline group-containing monomers can be used alone or in combination of two or more. Also, a copolymer of a monomer containing an oxazoline group and a monomer not containing it may be used. Commercially available oxazoline curing agents include the "Epocros" series manufactured by Nippon Shokubai Co., Ltd.

[0030] The carbodiimide-based curing agent is a compound containing two or more carbodiimide groups in one molecule. Examples of the carbodiimide-based curing agent include poly(4,4'-diphenylmethane carbodiimide), poly(dicyclohexylmethane carbodiimide), poly(diisopropylcarbodiimide), etc. Examples of commercially available carbodiimide-based curing agents include the "Carbodilite" series manufactured by Nisshinbo Chemicals Co., Ltd.

[0031] The aziridine-based curing agent is a compound containing two or more aziridine groups in one molecule. Examples of the aziridine-based curing agent include 2,2-bishydroxymethylbutanol-tris[3-(1-aziridinyl)propionate] and 4,4'-bis(ethyleneiminocarbonylamino)diphenylmethane, etc. Examples of commercially available aziridine-based curing agents include the "Chemitite" series manufactured by Nippon Shokubai Co., Ltd.

[0032] The addition ratio of the curing agent not containing a melamine component is 5 to 50 parts by weight, preferably 5 to 30 parts by weight, more preferably 10 to 20 parts by weight, based on 100 parts by weight of the alkyd resin.

[0033] <Surface resin layer> Although not particularly limited, at least one selected from urethane resin, alkyd resin, acrylic resin, and vinyl chloride resin is preferable for the surface resin layer. Urethane resin is a polymer compound containing urethane bonds, which is produced by the reaction of polyisocyanate and polyol, etc. Examples of polyisocyanates include aliphatic polyisocyanates such as methylene diisocyanate, hexamethylene diisocyanate, and trimethylhexamethylene diisocyanate; alicyclic polyisocyanates such as cyclohexane diisocyanate and isophorone diisocyanate; aromatic polyisocyanates such as toluene diisocyanate and methylene bisphenyl diisocyanate; adducts, biurets, isocyanurates of the above polyisocyanates; blocked isocyanates in which the isocyanate groups of the above polyisocyanates are protected with a blocking agent; and modified products of the above polyisocyanates. Examples of the modified products of the above polyisocyanates include polyisocyanate modified products in which the isocyanate compound is modified by allophanate bonds, urea bonds, uretdione bonds, carbodiimide bonds, etc. Polyols include polycarbonate polyols, polyether polyols, polyester polyols, etc., and urethane resins synthesized from them are called polycarbonate urethane resins, polyether urethane resins, and polyester urethane resins, respectively. Since the surface resin layer is excellent in weather resistance, heat resistance, and chemical resistance, a water-based polycarbonate urethane resin is preferred. If it is water-based, it is safe during production and use, environmentally friendly, and there is no problem with odor. Examples of commercially available water-based polycarbonate urethane resins, water-based polyether urethane resins, and water-based polyester urethane resins include the "Resamin" series manufactured by Dainichi Seika Kogyo Co., Ltd. and the "Nipolan" series manufactured by Tosoh Corporation. Alkyd resins that are the same as those used in the ink underlayer can be used.

[0034] An acrylic resin is a polymer compound obtained by polymerizing an acrylic monomer and its derivatives. Examples of acrylic monomers include acrylic acid and methacrylic acid derivatives such as methyl acrylate, ethyl acrylate, methyl methacrylate, 2-hydroxyethyl acrylate, methoxybutyl acrylate, etc., as well as acrylic acid and methacrylic acid. Each acrylic monomer may be used alone or two or more types may be used. Also, a copolymer with other monomers such as styrene, butadiene, and vinyl acetate may be used. Examples of commercially available acrylic resins include the "Acrylic" series manufactured by DIC Corporation.

[0035] A vinyl chloride resin is a polymer compound obtained by polymerizing a vinyl chloride monomer and its derivatives. The vinyl chloride monomer may be used alone or a copolymer with other monomers such as ethylene and vinyl acetate may also be used. Examples of commercially available vinyl chloride resins include the "Solvaine" series manufactured by Nissin Chemical Industry Co., Ltd. for vinyl chloride-vinyl acetate copolymer resins.

[0036] The thickness of the surface resin layer is preferably 10 to 50 μm, more preferably 15 to 45 μm. The thickness of the ink underlayer is preferably 10 to 50 μm, more preferably 15 to 45 μm. The thickness of the adhesive layer is preferably 15 to 60 μm, more preferably 20 to 55 μm. The thickness of the graphic sheet is preferably 100 μm or less, more preferably 50 to 100 μm. With this thickness, after being attached to a substrate such as a base plate, it is difficult to peel off, and a graphic sheet with high security can be obtained. Furthermore, it also has excellent low-temperature embossing properties. If the thickness of the graphic sheet exceeds 100 μm, it will cause problems in embossing or debossing properties, security properties, and heat-resistant yellowing properties.

[0037] The surface resin layer preferably contains a curing agent. Thereby, the surface resin layer can be provided with good solvent resistance. Examples of the curing agent added to the surface resin layer include melamine-based, carbodiimide-based, oxazoline-based, etc., among which melamine-based is preferred. It is preferable to add a formaldehyde scavenger to the surface resin layer. When a melamine-based curing agent is added to the surface resin layer, there is a problem that formaldehyde generated by thermal decomposition of the melamine-based curing agent reacts with the surface resin layer to cause yellowing, but this can be improved by adding a formaldehyde scavenger to the surface resin layer. As the formaldehyde scavenger, at least one selected from compounds having an amino group or an amide group in the molecule such as urea, ethylene urea, thiourea, and melamine is preferred. Examples of commercially available products containing the above compound include "Finex FC-KP" (trade name) [manufactured by DIC Corporation], which is a nitrogen-based formaldehyde scavenger, etc. The formaldehyde scavenger is preferably added in an amount of 0.01 to 10 parts by weight, more preferably 0.1 to 5 parts by weight, and still more preferably 0.1 to 2 parts by weight based on 100 parts by weight of the surface resin layer.

[0038] It is preferable to add at least one selected from blue pigments and purple pigments to the surface resin layer and / or the ink underlayer. Thereby, due to the influence of an ultraviolet absorber or the like contained to improve the weather resistance of each layer, there is a problem that the graphic sheet has a slight yellowish tint, but by adding at least one selected from blue pigments and purple pigments as the complementary color of yellow, the yellowish color of the graphic sheet can be canceled out. When each layer of the surface resin layer and the ink underlayer is 100 parts by weight, the addition amount of the pigment is preferably 0.001 to 1 part by weight, more preferably 0.01 to 0.1 part by weight, and still more preferably 0.01 to 0.05 part by weight.

[0039] The adhesive layer preferably uses an acrylic resin as the base polymer and is cured with a curing agent containing no aromatic components. One of the causes of yellowing is the yellowing of the adhesive layer. Conventional adhesive layers are formed with an acrylic resin as the base polymer and an isocyanate-based curing agent containing aromatics. Such aromatic isocyanate-based curing agents may cause yellow coloring because the aromatic ring easily absorbs light in the visible region. Therefore, by adding an isocyanate-based curing agent and an epoxy-based curing agent containing no aromatics, a graphic sheet excellent in heat-resistant yellowing can be obtained. As the epoxy-based curing agent, the same one as used in the ink underlayer can be used. When the acrylic resin is 100 parts by weight, the addition amounts of the isocyanate-based curing agent and the epoxy-based curing agent containing no aromatics are preferably 0.001 to 1 part by weight, more preferably 0.001 to 0.1 part by weight, and still more preferably 0.005 to 0.01 part by weight.

[0040] The adhesive layer can contain resins such as acrylic resins, natural rubbers, and rubber-based resins such as synthetic rubbers, but preferably contains an acrylic resin. Acrylic resins have high adhesive strength and high weather resistance. As the acrylic resin, a polymer-based acrylic resin mainly containing at least one of an acrylate copolymer and an acrylic prepolymer or a modified acrylic resin obtained by adding an adhesion promoter and a monomer imparting cohesive force to the acrylic resin is suitable.

[0041] At least one of the ink underlayer and the adhesive layer can be colored in any color. For example, white, green, yellow, red, blue, purple, black, etc. Among these, it is preferably colored white. In particular, it is preferable that the ink underlayer and the adhesive layer are colored white. The ink underlayer and the adhesive layer have high hiding properties, and the substrate cannot be seen even if it is thin. When the ink underlayer or the adhesive layer is 100 parts by weight, the addition amount of the colorant is preferably 1 to 50 parts by weight, more preferably 5 to 30 parts by weight, and still more preferably 5 to 10 parts by weight.

[0042] It is preferable as a product form that a protective film is attached to the outer surface of the surface resin layer and a release film is attached to the outer surface of the adhesive layer. If a protective film is attached to the outer surface of the surface resin layer, the inner layer can be protected, and if a release film is attached to the outer surface of the adhesive layer, it is convenient when attaching to the base plate.

[0043] As the protective film, for example, various commercially available surface protective films with a thickness of 30 to 90 μm can be used. It is used to prevent the surface from being scratched during transportation, processing, etc. After the graphic sheet is attached to the vehicle base plate and embossed, it is peeled off before forming the symbol ink layer on the convex surface. Therefore, it is necessary to follow the graphic sheet during embossing. As the release film, for example, a polyester (PET) film with a thickness of 25 to 50 μm can be used.

[0044] The thickness of the graphic sheet is preferably 300 μm or less, more preferably 100 to 300 μm, and even more preferably 150 to 250 μm. The graphic sheet preferably has a property that it is difficult to reuse, such as stretching or breaking when peeled off after being attached to the base material. This can prevent the theft of the graphic sheet and also prevent theft such as partial cutting of design parts such as emblems. The graphic sheet is preferably a sheet for a vehicle number plate. Using a graphic sheet for a vehicle number plate is useful not only for aesthetic effects but also for the promotional effects of international sports events, international expositions, local promotions, and various events.

[0045] The manufacturing method of the graphic sheet with a protective film of the present invention includes the following steps. Step A: A surface resin layer is formed on the surface of the base film for the process by the casting method. Step B: An ink-receiving layer is formed on the surface of the surface resin layer by the casting method. Step C: A printing layer is formed on the surface of the ink-receiving layer by inkjet printing. D A ink underlayer is formed on the surfaces of the ink receiving layer and the printing layer by the casting method. E An adhesive layer is formed on the surface of a separately prepared release film by the casting method. F The adhesive layer is bonded to the surface of the ink underlayer. G The base material film for the process is peeled off and a protective film is laminated on the surface resin layer. For example, the polyethylene terephthalate film (PET, thickness 50 μm) of the graphic sheet body is peeled off, and a protective film is bonded for the purpose of protecting the graphic sheet and following the graphic sheet during embossing, thereby obtaining a graphic sheet with a protective film. Since the surface resin layer, the ink receiving layer, the ink underlayer, and the adhesive layer are formed by the casting method, the adhesion between the layers is high, the overall thickness can be reduced, it is difficult to peel off without damage, and a highly secure graphic sheet can be obtained. Regarding the formation process of the adhesive layer, here, after forming the adhesive layer on the release PET, the process of bonding the adhesive layer to the surface of the ink underlayer has been described. However, after forming the adhesive layer on the surface of the ink underlayer, a release PET film may be bonded on the adhesive layer.

[0046] The method of using the graphic sheet with a protective film of the present invention is as follows: (1) The graphic sheet with the protective film is bonded onto a base plate. (2) A symbol is created by embossing or debossing. (3) The protective film is peeled off. (4) Then, a symbol ink layer is placed on the symbol and baked to obtain a number plate with the graphic sheet attached. A water-repellent, oil-repellent, and stain-proof spray may be applied to the number plate with the graphic sheet attached. The baking temperature can be approximately 125°C to 160°C as an example.

[0047] The following will be described with reference to the accompanying drawings. In the following drawings, the same reference numerals denote the same components. FIG. 1 is a schematic cross-sectional view of a graphic sheet 1 according to an embodiment of the present invention. This graphic sheet 1 includes a surface resin layer 2, an ink receiving layer 3 on the back side of the surface resin layer 2, a printing layer 4 on the back side thereof, an ink underlayer 5, and an adhesive layer 6 in this order. Arrow EY is the viewing direction (the same applies hereinafter). FIG. 2 is a schematic cross-sectional view of a graphic sheet 10 with a protective film in which a protective film 7 is attached to the outside of the surface resin layer 2 of the graphic sheet 1 and a release film 8 is bonded to the outside of the adhesive layer 6. The product form is as shown in FIG. 2. FIGS. 3A-F are schematic cross-sectional views showing the manufacturing process of the graphic sheet 10 with a protective film. FIG. 3A is a process of forming a polycarbonate-based urethane surface resin layer 2 on the surface of a base film 9 for the process by a casting method. FIG. 3B is a process of forming an ink receiving layer 3 on the surface of the surface resin layer 2 and forming a printing layer 4 on the surface thereof by inkjet printing. FIG. 3C is a process of forming an ink underlayer 5 containing an alkyd melamine resin on the surfaces of the ink receiving layer 3 and the printing layer 4 by a casting method. FIG. 3D is a process of forming an adhesive layer 6 on the surface of a separately prepared release film 8 by a casting method. FIG. 3E is a process of bonding the adhesive layer 6 to the surface of the ink underlayer 5. FIG. 3F is a process of peeling off the base film 9 for the process and laminating the protective film 7 on the surface resin layer 2. FIG. 4 is a schematic front view of a number plate 11 manufactured by attaching the graphic sheet with a protective film to a base plate for a vehicle, performing embossing, peeling off the protective film, and forming a symbol ink layer on the surface of the convex portion. The patterns (peripheral heart shape and rounded shape) around the characters are colored image portions 14a, 14b. Also, designs of various emblems may be added at arbitrary positions. The printing layer is L according to the CIE color difference formula defined by the International Commission on Illumination in accordance with JIS Z 8781-4:2013 *It is preferable that an image including chromatic colors with values from 0 to 85 is formed. L * The value represents the lightness of the color as a value from 0 to 100, indicating that the closer to 0, the darker, and the closer to 100, the brighter. L * In the case of a chromatic color image with values from 0 to 85, the printing layer was likely to peel off in a conventional graphic sheet. However, in the graphic sheet of the present invention, the printing layer can either not peel off or adhere to the ink-receiving layer so strongly that the printing layer undergoes cohesive failure.

[0048] Figure 5 is a schematic partial cross-sectional view of Figure 4. First, a graphic sheet with a protective film is bonded onto the base plate 12, embossed to create the symbol "Osaka 600 or 20 - 25" in Figure 4. After peeling off the protective film, a symbol ink layer 13 is placed on this symbol. 1 is the graphic sheet with the protective film peeled off. Then, the ink is baked. As an example, the baking temperature can be approximately 125°C to 160°C. Thereby, a number plate with a highly secure graphic sheet attached can be obtained.

Examples

[0049] Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to only these examples. In the following examples, "parts" represents "parts by weight" unless otherwise specified, and "%" represents "weight%" unless otherwise specified. Also, the compounding amount (addition amount) of the curing agent in the following table is expressed in parts by weight in terms of solid content.

[0050] <Printing Method> An inkjet printer manufactured by Mimaki Co., Ltd., product number JV - 300, was used. For cyan (C), magenta (M), yellow (Y), and orange (Or), printing was performed at a set density of 10 to 100%. The set density of 10 to 100% is also indicated as "ink density 10 to 100%". <Adhesion Evaluation: Peel - off Test> As shown in Figs. 6A-B and 7A-B, first, the graphic sheet 1 was attached to an aluminum plate 13 having a thickness of 1 mm, and after leaving it at 125°C for 10 minutes, the temperature was lowered to room temperature of 25°C, and a peel-off test was performed. In the peel-off test, a cutter was inserted from the surface resin layer side at an angle of α = 45° and cut. Next, an adhesive tape was attached from above the surface resin layer in a direction perpendicular to the cut part, and it was peeled off vigorously at an angle of β = about 60°. Cohesive failure or interfacial failure was determined by observation with an optical microscope. Fig. 6A is a schematic cross-sectional view showing a peel-off test of a graphic sheet in one embodiment of the present invention, and Fig. 6B is a schematic cross-sectional view showing cohesive failure in the same embodiment. Fig. 7A is a schematic cross-sectional view showing a peel-off test of a graphic sheet of a conventional example, and Fig. 7B is a schematic cross-sectional view showing interfacial failure in the same embodiment. Peel-off test evaluation criteria ○: The adhesive tape peeled off smoothly from the surface resin layer, with no abnormalities. Δ: The ink receiving layer is subjected to cohesive failure, and peeling or lifting occurs. ×: The interface between the surface resin layer and the ink layer is destroyed, and peeling or lifting occurs. <Color measurement evaluation> According to JIS Z 8781-4:2013, the CIE color difference formula specified by the International Commission on Illumination is used. * The value was calculated. * The value represents the brightness of the color on a scale of 0 to 100, with the closer to 0 the darker the color, and the closer to 100 the brighter the color. Measurements were performed using a portable spectrophotometer manufactured by X-Rite, called "eXact Advanced." This spectrophotometer "eXact Advanced" has an optical system with an illumination angle of 45 degrees and a light receiving angle of 0 degrees, measures with a measuring diameter of 2.0 mm, and is capable of measuring in multiple color spaces such as CIE L*a*b*, CIE L*C*h°, and CIE XYZ. CIE L*a*b* was used to calculate the L* value, and measurements were performed using a D65 light source / observer viewing angle of 2 degrees and M0(No) without a filter for color-related values.

[0051] [Common materials] <Surface resin layer> (1) Aliphatic polycarbonate urethane resin solution "Resamin D-6300" (trade name) [manufactured by Dainichi Seika Kogyo Co., Ltd.] (solid content 30%) 80.0 parts (2) Polymer-based ultraviolet absorber "XL07-0016" (trade name) [manufactured by Lion Specialty Chemicals Co., Ltd.] (solid content 32%) 20 parts (3) Urethane resin "SN Thinner A-812" (trade name) [manufactured by San Nopco Ltd.] (solid content 100%) 0.2 part (4) Acetylene glycol-based resin "Olfin E-1004" (trade name) [manufactured by Nisshin Chemical Industry Co., Ltd.] (solid content 100%) 0.5 part <Ink underlayer> I Composition of alkyd melamine resin solution (1) Alkyd resin solution "Bekkolite CF-743-50" (trade name) [manufactured by DIC Corporation] (solid content 50%) 46 parts (2) Vinyl chloride-vinyl acetate copolymer resin solution (solid content 25%) 27 parts (3) Levelling agent (solid content 0.05%) 0.06 part (4) Plasticizer "Polysizer W-2310" (trade name) [manufactured by DIC Corporation] (solid content 99%) 1.3 parts (5) Epoxidized fatty acid glyceride "A-130P" (trade name) [manufactured by ADEKA Corporation] (solid content 100%) 0.3 part (6) Antioxidant "EVERNOX-10" (trade name) [manufactured by EVERSPRING CHEMICAL CO., LTD.] (solid content 100%) 0.15 part (7) Ultraviolet absorber "Disizer E" (trade name) [manufactured by Sankyo Kasei Co., Ltd.] (solid content 100%) 1.1 parts (8) Methylated melamine resin (solid content 60%) 8.4 parts (9) Butylated melamine resin (solid content 60%) 4.2 parts (10) Alkyl acidic phosphate ester as a catalyst (solid content 60%) 0.15 part II Composition of alkyd isocyanate-based transparent resin solution (1) Alkyd resin solution "Bekkolite CF-743-50" (trade name) [manufactured by DIC Corporation] (solid content 50%) 46 parts (2) Vinyl chloride - vinyl acetate copolymer resin solution (solid content 25%) 27 parts (3) Levelling agent (solid content 0.03%) 0.06 part (4) Plasticizer "Polysizer W - 2310" (trade name) [manufactured by DIC Corporation] (solid content 99%) 1.3 parts (5) Epoxidized product of fatty acid glyceryl ride "A - 130P" (trade name) [manufactured by ADEKA Corporation] (solid content 100%) 0.3 part (6) Antioxidant "EVERNOX - 10" (trade name) [manufactured by EVERSPRING CHEMICAL CO., LTD.] (solid content 100%) 0.15 part (7) UV absorber "Disizer E" (trade name) [manufactured by Sankyo Kasei Co., Ltd.] (solid content 100%) 1.1 parts (8) Isocyanate - based curing agent "Varnock DN - 950" (trade name) [manufactured by DIC Corporation] 11.3 parts Note that the ink underlayer may contain 4.0 parts of titanium oxide paste to be a white resin. <Adhesive layer> (1) Acrylic resin "Acryset AST - 8207" (trade name) [manufactured by Nippon Shokubai Co., Ltd.] (solid content 35%) 100 parts (2) As solvent, ethyl acetate 10 parts (3) Toluene 20 parts (4) As white colorant, titanium oxide "Titanium Paste E" (trade name) [manufactured by Nippon Shokubai Co., Ltd.] 10 parts (5) As curing agent, alicyclic epoxy resin curing agent "TETRAD - C" (trade name) [manufactured by Mitsubishi Gas Chemical Company, Inc.] 0.01 part

[0052] (Example 1) <Surface resin layer> A polycarbonate - based urethane transparent resin solution was cast - coated on a 50 - μm - thick polyester film "CM50" (trade name) [manufactured by Nakamoto Pax Co., Ltd.], which is a base film for the process, so that the dried thickness would be 25 μm. It was then heated and dried in the order of 50 seconds at 70°C, 50 seconds at 100°C, 1 minute and 40 seconds at 120°C, and 50 seconds at 100°C under normal pressure to form a surface resin layer. The thickness was 25 μm. <Print - receiving layer> On the surface resin layer, a vinyl chloride-vinyl acetate resin solution (manufactured by Nissin Chemical Industry Co., Ltd., trade name "Solvaine C5R") was used, diluted with a solvent: toluene to a solid concentration of 21% to form a casting solution, and a printing acceptance layer was formed by the casting method. The thickness was 5 μm. <Printing layer> A printing layer was formed on the printing acceptance layer by inkjet printing. <Ink underlayer> An alkyd melamine resin solution was applied onto the printing layer by the casting method so that the thickness after drying would be 20 μm, and heated and dried in the order of 70 °C for 2 minutes and 10 seconds, 100 °C for 1 minute and 5 seconds, and 130 °C for 2 minutes and 10 seconds under normal pressure to form an ink underlayer. The thickness was 20 μm. <Adhesive layer> A white adhesive solution A was applied onto the release-treated surface of a 38-μm-thick polyester film ("Ester Film E7002 #38" manufactured by Toyobo Co., Ltd.) by the casting method so that the thickness after drying would be 33 μm, and heated and dried in the order of 70 °C for 1 minute and 100 °C for 2 minutes under normal pressure to produce an adhesive layer. The thickness was 33 μm. <Laminating and bonding> This adhesive layer's adhesive surface and the ink underlayer were bonded together. After peeling the process substrate film from the surface resin layer, a protective film was bonded to the surface resin layer to obtain a graphic sheet body. The thickness of this graphic sheet body was 190 μm.

[0053] (Example 2) As an ink underlayer, it was carried out in the same manner as in Example 1 except that an alkyd melamine resin solution was replaced with an alkyd isocyanate resin solution. The thickness of the graphic sheet body was 190 μm.

[0054] (Example 3) As the printing receptive layer, vinyl chloride-vinyl acetate-vinyl alcohol resin (manufactured by Nissin Chemical Industry Co., Ltd., trade name "Solvaine A") was used, diluted with a solvent: toluene, and made into a casting solution with a solid concentration of 15%. The printing receptive layer was formed by the casting method. The thickness was 5 μm. Otherwise, it was carried out in the same manner as in Example 1. The thickness of the graphic sheet body was 190 μm.

[0055] (Example 4) As the ink underlayer, it was carried out in the same manner as in Example 3 except that an alkyd isocyanate resin solution was used instead of the alkyd melamine resin solution. The thickness of the graphic sheet body was 190 μm.

[0056] (Example 5) As the printing receptive layer, a polyester-based polyurethane resin solution (manufactured by Dainichi Seika Kogyo Co., Ltd., trade name "Resamin NE-302HV") was used, diluted with a solvent: toluene and isopropyl alcohol, and made into a casting solution with a solid concentration of 10%. The printing receptive layer was formed by the casting method. The thickness was 5 μm. Otherwise, it was carried out in the same manner as in Example 1. The thickness of the graphic sheet body was 190 μm.

[0057] (Example 6) As the ink underlayer, it was carried out in the same manner as in Example 5 except that an alkyd isocyanate-based white resin solution was used instead of the alkyd melamine-based white resin solution. The thickness of the graphic sheet body was 190 μm.

[0058] (Example 7) As the printing receptive layer, a polyester-based polyurethane resin solution (manufactured by DIC Corporation, trade name "Hydran APX-101H") was used, diluted with a solvent: water, and made into a casting solution with a solid concentration of 40%. The printing receptive layer was formed by the casting method. The thickness was 5 μm. Otherwise, it was carried out in the same manner as in Example 1. The thickness of the graphic sheet body was 190 μm.

[0059] (Example 8) As an ink underlayer, it was carried out in the same manner as in Example 7 except that the alkyd melamine-based white resin solution was replaced with an alkyd isocyanate-based white resin solution. The thickness of the graphic sheet body was 190 μm.

[0060] (Comparative Example 1) It was carried out in the same manner as in Example 1 except that the printing acceptance layer was not provided.

[0061] (Comparative Example 2) It was carried out in the same manner as in Example 2 except that the printing acceptance layer was not provided. The above conditions and results are summarized in Tables 1 to 6.

[0062]

Table 1

[0063]

Table 2

[0064]

Table 3

[0065]

Table 4

[0066]

Table 5

[0067]

Table 6

[0068] In Tables 3 to 6 above, the L* values marked with × or a gray background color correspond to the portions where adhesion peeling due to interfacial failure occurred. When performing magenta single-color printing, in the comparative example, when L* is 68 or less, it peels off due to interfacial fracture. However, depending on the setting of the ink-receiving layer, it does not peel off when L* is more than 50 and 68 or less, and even when L* is 49 or less, it peels off due to cohesive fracture. When a more preferable ink-receiving layer is set, it does not peel off even when L* is 49 or less. Similarly, in the case of yellow, in the comparative example, it peels off due to interfacial fracture when L* is 87 or less, but it does not peel off when L* is 87 or less depending on the setting of the ink-receiving layer. Similarly, in the case of orange, in the comparative example, it peels off due to interfacial fracture when L* is 86 or less, but it does not peel off when L* is more than 71 and 86 or less depending on the setting of the ink-receiving layer, and even when L* is 70 or less, it peels off due to cohesive fracture. When a more preferable ink-receiving layer is set, it does not peel off even when L* is 70 or less.

[0069] (Example 9) Under the conditions of Example 1, the adhesion evaluation was performed when the thickness of the receiving layer was changed. That is, the ink-receiving layer material: polyvinyl chloride-vinyl acetate (Solvay C5R), and the ink underlayer: alkyd melamine were evaluated. The results are shown in Table 7.

[0070]

Table 7

[0071] As is clear from the above results, it was confirmed that Examples 1 to 9 are graphic sheets in which the printed layer does not peel off or the printed layer undergoes cohesive fracture in the peel-off test.

Industrial Applicability

[0072] The graphic sheet of the present invention can be used as a vehicle number plate, and can also be used as a signboard, an automobile, a decorative film or sheet for a building, etc.

Explanation of Signs

[0073] 1 Graphic sheet 2 Surface resin layer 3 Ink-receiving layer 4 Printed layer 5 Ink underlayer 6 Adhesive layer 7 Protective film 8 Release film 9 Substrate film for process 10 Graphic sheet with protective film 11 Number plate 12 Base plate 13 Symbol ink layer 14a, 14b Colored image part EY Visual recognition direction

Claims

1. A graphic sheet comprising a surface resin layer, an ink receiving layer, a printing layer, an ink underlayer, and an adhesive layer in this order, wherein the printing layer is an inkjet printing layer, and when cut at an angle of 45° from the surface resin layer side and subjected to a peel-off test, the printing layer does not peel off or the printing layer undergoes cohesive failure.

2. The graphic sheet according to claim 1, wherein the ink receiving layer is a copolymer or a multi-component copolymer resin containing a vinyl group and / or a resin containing a urethane bond.

3. The graphic sheet according to claim 1 or 2, wherein the ink receiving layer is at least one selected from the group consisting of a vinyl chloride-vinyl acetate-vinyl alcohol resin, a vinyl chloride-vinyl acetate-hydroxyacrylate resin, a vinyl chloride-vinyl acetate resin, and a polyester-based polyurethane resin.

4. The graphic sheet according to claim 1 or 2, wherein the thickness of the ink receiving layer is 0.1 to 30 μm.

5. The graphic sheet according to claim 1 or 2, wherein the surface resin layer is at least one selected from the group consisting of a urethane resin, an alkyd resin, an acrylic resin, and a vinyl chloride resin.

6. The graphic sheet according to claim 5, wherein the urethane resin is one selected from the group consisting of an aqueous polycarbonate-based urethane resin, an aqueous polyether-based urethane resin, and an aqueous polyester-based urethane resin.

7. The graphic sheet according to claim 1 or 2, wherein the surface resin layer, the ink receiving layer, the printing layer, the ink underlayer, and the adhesive layer are a transparent resin or a resin containing an arbitrary coloring pigment.

8. The graphic sheet according to claim 1 or 2, wherein the thickness of the graphic sheet is 300 μm or less.

9. The printing layer conforms to JIS Z 8781-4:2013 and has an L value according to the CIE color difference formula defined by the International Commission on Illumination. * The graphic sheet according to claim 1 or 2, on which an image including a chromatic color with an L value of 0 to 85 is formed.

10. The graphic sheet according to claim 1 or 2, wherein the graphic sheet is a sheet for a vehicle number plate.

11. A graphic sheet with a protective film, wherein in the graphic sheet according to claim 1 or 2, a protective film is attached to the outer surface of the surface resin layer, and a release film is attached to the outer surface of the adhesive layer.

12. A method for manufacturing the graphic sheet with a protective film according to claim 11, wherein a surface resin layer is formed on the surface of a base material film for step A by a casting method, B Form an ink-receiving layer on the surface of the surface resin layer by the casting method, C Form a printing layer on the surface of the ink-receiving layer by inkjet printing, D Form an ink underlayer on the surfaces of the ink-receiving layer and the printing layer by the casting method, E Form an adhesive layer on the surface of a separately prepared release film by the casting method, F Bond the adhesive layer to the surface of the ink underlayer, G A method for manufacturing a graphic sheet with a protective film, including the step of peeling off the base material film for the process and laminating the protective film on the surface resin layer.

13. A method of using the graphic sheet with a protective film according to Claim 11, Bond the graphic sheet with the protective film onto a base plate, Create a symbol by embossing or debossing, Peel off the protective film, Thereafter, place a symbol ink layer on the symbol and use it as a number plate with the graphic sheet attached.

Images