JP2008279687A - Resin sheet-coated metal plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin sheet-coated metal plate that hardly causes separation of a coat resin from a metal plate during a secondary work such as a bending work, a deep-drawing work and the like, and shows high water resistance. <P>SOLUTION: The resin sheet-coated metal plate comprises: the metal plate (A); an adhesive layer B formed on at least one surface of the metal plate (A) and composed of a self-emulsification-type urethane resin emulsion (B) containing a urethane resin having a glass transition temperature of a resin component of -65°C to -10°C; an adhesive layer C formed on the adhesive layer B and composed of a mixture of 10 to 40 mass% (solid content) of the component (B) and 90 to 60 mass% (solid content) of the self-emulsification-type polyester resin emulsion (C) containing a polyester resin having a glass transition temperature of 20°C to 90°C, a number average molecular weight of 4,000 to 18,000, an acid value of 5 to 25 mgKOH/g, and a hydrophilic group; and a thermoplastic resin sheet (D) overlying the surface of the adhesive layer C. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a resin sheet-coated metal plate. More specifically, it is a resin sheet-covered metal plate that uses an adhesive that can pass hazardous materials regulations without fear of environmental pollution, and the resin sheet is removed from the metal plate during secondary processing such as bending and drawing. The present invention relates to a resin sheet-coated metal plate that is difficult to peel off and has excellent water resistance.

  On the steel sheet surface, a vinyl chloride resin (hereinafter abbreviated as PVC) sheet, a so-called PVC steel sheet obtained by applying a PVC sol to a steel sheet, a polyester steel sheet in which a polyester resin sheet is laminated on a steel sheet, etc. Because of its beautiful appearance and excellent durability, it has been used in many applications such as home appliances, furniture products, and building materials. As a manufacturing method of such a PVC steel sheet and a polyester steel sheet, (1) a method of applying an adhesive to the surface of the steel sheet and baking it, and laminating a PVC sheet or a polyester resin sheet on this baking surface, (2) steel There is known a method in which an adhesive is applied to a ridge, baked and continuously transferred, and a PVC or polyester resin is melt-extruded into a sheet on the steel sheet, and both are pressurized and fused. In any of the above methods (1) and (2), an adhesive is used to improve the adhesion between the steel sheet and the PVC sheet or the polyester resin sheet and the secondary workability. .

As such an adhesive, since the adhesiveness with respect to a metal plate or a PVC sheet is favorable, polyester-type resin adhesives, such as a polyester resin or a modified polyester resin, etc. are proposed (patent documents 1-patent documents 7). reference). However, all of the adhesives described in these publications are obtained by dissolving a polyester resin in an organic solvent. Adhesives containing organic solvents tend to be avoided from the viewpoint of environmental pollution, resource saving, dangerous goods regulations by the Fire Service Act, and workplace environment improvement in recent years. Further, an adhesive using a polyester resin is insufficient in water resistance, particularly hot water resistance, and its use is limited in outdoor applications where strict adhesive performance is required. Furthermore, adhesives that do not use organic solvents have been proposed using polyester resins and polyurethane resins as water-based adhesives, but all have disadvantages such as poor processability and poor water resistance, Or, it did not exhibit good adhesion to both the PVC sheet and the polyester resin sheet.
JP-A-1-174582 Japanese Patent Laid-Open No. 5-70758 JP-A-6-313162 JP-A-9-31438 Japanese Patent No. 2525391 Japanese Patent No. 2618218 JP 2003-246974 A

As a result of intensive investigations to provide a technique that eliminates the above-mentioned drawbacks of the prior art, the present inventor has completed the present invention. That is, the object of the present invention is as follows.
1. To provide a metal sheet coated with a resin sheet that uses an adhesive that does not pose a risk of environmental pollution and does not violate regulations on dangerous goods.
2. An object of the present invention is to provide a resin sheet-covered metal plate excellent in interfacial adhesion, in which the resin sheet is hardly peeled even when the metal plate is deformed during the secondary processing.

In order to solve the above problems, the present invention forms an adhesive layer B composed of the following component (B) on at least one surface of the metal plate (A), and on the adhesive layer B, the following component (B): Is formed from a mixture of 10 to 40% by mass (solid content) and 90 to 60% by mass (solid content) of the following component (C), and the surface of the adhesive layer C is thermoplastic. A resin sheet-covered metal plate is provided, wherein the resin sheet (D) is laminated.
Component (B): Self-emulsifying urethane resin emulsion (PUE) containing urethane resin (PU) having a glass transition temperature of −65 to −10 ° C.
(C) component: The glass transition temperature is 20 ° C. to 90 ° C., the number average molecular weight is 4,000 to 18,000, the acid value is 5 to 25 mg KOH / g, and includes a polyester resin having a hydrophilic group (PE). Self-emulsifying polyester resin emulsion (PEE).

The present invention is as described in detail below, and has the following particularly advantageous effects, and its industrial utility value is extremely large.
1. The resin sheet-covered metal plate according to the present invention uses an adhesive that does not contain an organic solvent as an adhesive for bonding the resin sheet and the metal plate. Will not conflict.
2. The resin sheet-covered metal plate according to the present invention is excellent in appearance (surface smoothness) because the adhesive layer that bonds the resin sheet and the metal plate is constituted by two layers.
3. The resin sheet-covered metal plate according to the present invention is excellent in the adhesion between the metal plate and the resin sheet, and it is difficult to cause peeling or cracking of the adhesive layer during the secondary processing, and a secondary processed product having a beautiful appearance is obtained. It is done.

  Hereinafter, the present invention will be described in detail. The sheet in the present invention refers to a product that is thin and flat for the length and width according to the definition in JIS, and the boundary between the sheet and the film is not clear. Since there is no film, it shall include a film. In the present invention, the self-emulsifying emulsion is an emulsion having a hydrophilic carboxyl group in the molecule and exhibiting water solubility or water dispersibility by itself.

  In the resin sheet-covered metal plate according to the present invention, the surface of the metal plate A is coated with a thermoplastic resin sheet (D) through an adhesive layer composed of two specific layers. In the present invention, the metal plate A is a thin metal plate that serves as a base for the resin sheet-coated metal plate. Specific examples of the metal plate A include hot rolled steel plate, cold rolled steel plate, hot dip galvanized steel plate, electrogalvanized steel plate, nickel plated steel plate, tin plate, tin-free steel plate, brass plate, copper plate, aluminum plate, aluminum alloy plate. And stainless steel plate. These metal plates may have a chemically treated surface. Examples of the chemical treatment include plating treatment, immersion chromic acid treatment, chromic acid chromic acid treatment, zinc chromate treatment, alumite treatment, primer coating treatment, and the like.

  The plating on the surface of the metal plate A may be any of single-layer plating, multi-layer plating, alloy plating and the like. In order to improve the adhesion between the metal plate and the adhesive, the surface of the metal plate subjected to the above treatment is further treated with a coupling agent such as a silane coupling agent or a titanium coupling agent, acid treatment, alkali treatment, ozone. Chemical treatment such as ion treatment, plasma treatment, glow discharge treatment, arc discharge treatment, discharge treatment such as corona treatment, ultraviolet ray treatment, X-ray treatment, gamma ray treatment, electromagnetic wave irradiation treatment such as laser treatment, and other flame treatment Various surface treatments such as surface treatment may be performed. The thickness of the metal plate varies depending on the application of the resin sheet-coated metal plate, and is usually selected in the range of 0.1 to 5 mm. For the unit bath use, a thickness of 0.3 to 0.8 mm is used.

  The adhesive layer in the resin sheet-coated metal plate according to the present invention is composed of two specific layers. One layer constituting the adhesive layer B is the component (B), that is, the adhesive layer B formed from a self-emulsifying urethane resin emulsion (PUE) (hereinafter, sometimes simply referred to as B layer). The other layers are the component (C), that is, a self-emulsifying urethane resin emulsion (PUE) of 10 to 40% by mass (meaning solid matter in the emulsion, the same meaning hereinafter), and a polyester resin emulsion. (PEE) Adhesive layer C formed from a mixture of 60 to 90% by mass (hereinafter sometimes simply referred to as C layer).

  The adhesive layer B in the resin sheet-coated metal plate according to the present invention is constituted by a self-emulsifying urethane resin emulsion (PUE). The urethane resin (PU) is a polymer polyol component (a) (hereinafter sometimes abbreviated as “component a”), a compound (b) having two or more hydroxyl groups and one or more carboxyl groups (hereinafter referred to as component b). Organic polyisocyanate component (c) (hereinafter sometimes abbreviated as component c), chain extender component (d), polymerization terminator component (e), salt forming agent as necessary. What is obtained by making it react in presence of (f).

  Examples of component a include polyether polyol (a1), polyester polyol (a2), polylactone polyol (a3), polycarbonate polyol (a4), and polyolefin polyol (a5). Specific examples of the polyether polyol (a1) include those obtained by polymerizing or copolymerizing alkylene oxides such as ethylene oxide, propylene oxide, 1,2-butylene oxide, and tetrahydrofuran. More specifically, polyethylene glycol, polypropylene glycol, polyoxyethylene-polyoxypropylene (block copolymer or random copolymer) glycol, polyoxyethylene-polytetramethylene ether glycol (block copolymer or random copolymer), poly Examples include tetramethylene ether glycol.

  Examples of the polyester polyol (a2) include those obtained by polycondensation of an aliphatic dicarboxylic acid and / or an aromatic dicarboxylic acid and a dihydric alcohol. Examples of the aliphatic dicarboxylic acid include succinic acid, adipic acid, sebacic acid, glutaric acid, and azelaic acid. Examples of the aromatic dicarboxylic acid include isophthalic acid and terephthalic acid. Examples of the dihydric alcohol include ethylene. Examples include glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, 3-methyl-1,5-pentadiol, neopentyl glycol, 1,4-dihydroxymethylcyclohexane, and the like. More specifically, polyethylene adipate diol, polybutylene adipate diol, pohexamethylene adipate diol, polyneopentyl adipate diol, polyethylene / butylene adipate diol, poly-3-methylpentane adipate diol, polybutylene isophthalate diol, etc. It is done.

  Specific examples of the polylactone polyol (a3) include polycaprolactone diol, polycaprolactone triol, and poly-3-methylvalerolactone diol. Specific examples of the polycarbonate polyol (a4) include polyhexamethylene carbonate diol. Specific examples of the polyolefin polyol (a5) include polybutadiene glycol, polyisobutylene glycol, and hydrides thereof. The component a exemplified above may be a single type or a mixture of two or more types. Among these components a, preferred are polyether polyol, polyester polyol, polylactone polyol and polycarbonate polyol.

  The compound component (b) (component b) having two or more hydroxyl groups and one or more carboxyl groups in the molecule may be included in the molecular chain of the urethane resin (PU) to impart hydrophilicity to the urethane resin. it can. Examples of component b include dimethylol alkanoic acid such as dimethylolacetic acid, dimethylolpropionic acid, and dimethylolbutyric acid. Of these, dimethylolpropionic acid is preferred. The quantity which contains the component b is 20 mol% or less with respect to the component a used for urethane resin manufacture.

  The organic polyisocyanate component (c) (component c) has two or more isocyanate groups (NCO groups) in one molecule, and has three or more. It is preferable to have two or more isocyanate groups (NCO groups) in one molecule since adhesion and workability can be improved. Specifically, aliphatic diisocyanate (c1) having 2 to 12 carbon atoms (excluding carbon in the NCO group, the same shall apply hereinafter), alicyclic diisocyanate (c2) having 4 to 15 carbon atoms, carbon number 8-12 araliphatic diisocyanate, C6-C20 aromatic diisocyanate (c3), aliphatic diisocyanate, etc. are said.

  Specific examples of the aliphatic diisocyanate (c1) include hexamethylene diisocyanate and lysine diisocyanate. Specific examples of the alicyclic diisocyanate (c2) include cyclohexylmethane diisocyanate, isophorone diisocyanate, cyclohexane diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated xylylene diisocyanate, and the like. Specific examples of the aromatic diisocyanate (c3) include tolylene diisocyanate, α, α, α ′, α′-tetramethylxylylene diisocyanate, diphenylmethane diisocyanate, naphthylene diisocyanate, xylylene diisocyanate, and the like. Furthermore, it may be a modified product of these diisocyanates. The modified product refers to a diisocyanate modified by a conventionally known method. For example, an isocyanate compound having an allophanate group, a burette group, a carbodiimide group, a uretonimine group, a uretdione group, an isocyanurate group, or the like, and an adduct type isocyanate compound modified with a polyfunctional alcohol such as trimethylolpropa may be mentioned. . Block isocyanates in which some or all of the isocyanate groups of the modified product are stabilized with caprolactam, phenol, oxime, organic amine or the like may be used. Component c is not limited to those exemplified above. These exemplified components c may be one kind or a mixture of two or more kinds. Many products corresponding to the component c exemplified above are commercially available and can be easily obtained.

  Specific examples of the chain extender component (d) (component d) to be included in the resin component as necessary include a low molecular polyol (d1) and a polyamine (d2). As the low molecular polyol (d1), for example, the dihydric alcohol mentioned as the raw material of the polyester polyol, and its alkylene oxide low molar adduct (number average molecular weight less than 500), alkylene oxide low molar adduct of bisphenol (number average) Molecular weight less than 500), trihydric alcohols such as glycerin, trimethylol ethane, and trimethylol propane, and alkylene oxide low molar adducts thereof (number average molecular weight less than 500). The polymerization terminator component (e) contained in the resin component as necessary includes low molecular monoalcohols such as methanol, butanol and cyclohexanol, and alkanols such as mono- and di-ethylamine, mono- and di-butylamine. Examples include amines.

  Examples of the salt forming agent (f) include trialkylamines such as trimethylamine, triethylamine, triisopropylamine, tri-n-propylamine, tri-n-butylamine, and N-alkyl such as N-methylmorpholine and N-ethylmorpholine. N-dialkylalkanolamines such as morpholines, N-dimethylethanolamine, N-diethylethanolamine and the like can be mentioned. The usage-amount of the component f is 20 mol% or less with respect to the total amount of the component a used for urethane resin manufacture, the component b, and the component c. The components that can be included in the resin component as necessary may be one kind or a mixture of two or more kinds.

  Urethane resin (PU) is reacted in the presence or absence of an organic solvent by adding a chain extender d or a polymerization terminator e, if necessary, in addition to component a, component b and component c. Can be manufactured. Urethane resin (PU) has a hydrophilic carboxyl group or sulfonic acid group in the molecular chain, and itself exhibits water-solubility or water-dispersibility, so it can be called a self-emulsifying emulsion. In the present invention, the hydrophilic group is preferably a carboxyl group. The carboxyl group present in the molecular chain can be confirmed by IR, NMR method or the like. The self-emulsifying type urethane resin emulsion is prepared by neutralizing the carboxyl group-containing urethane resin prepared as described above with a salt-forming agent (f) or mixing with water while neutralizing to form a dispersion (emulsion). Thereafter, a solvent is removed as necessary to obtain a self-emulsifying urethane resin emulsion in which urethane resin particles are dispersed.

  In order to accelerate the reaction, an amine catalyst used in a usual urethane resin forming reaction, or dioctyltin dimaleate, dibutyltin dilaurate, stannous octylate, dibutyltin oxide, bis (tri-n-butyl) Tin-based catalysts such as tin oxide) can be used. In the case of using an organic solvent, a solvent that is water-soluble and has a boiling point comparable to or lower than that of water is preferable. Specific examples include acetone, methyl ethyl ketone, tetrahydrofuran, and dioxane.

  The production method of the urethane resin emulsion (A) is not particularly limited. The urethane resin emulsion (A) may be a commercially available product as long as it has the above-mentioned characteristics. Examples of commercially available urethane resin emulsions (A) include Sanyo Kasei Kogyo Co., Ltd., Permarin (all trade names), Dai-ichi Kogyo Seiyaku Superflex (trade names), Dainippon Ink Co., Ltd. Bondic (trade name) and the like are listed.

  The urethane resin (PU) has a glass transition temperature (Tg) in the range of −65 to −10 ° C. When Tg is lower than −65 ° C., it is difficult to produce the urethane resin itself. Conversely, when Tg is higher than −10 ° C., the adhesiveness to the thermoplastic resin sheet (E) tends to be lowered, which is not preferable. In the present invention, the glass transition temperature of the urethane resin (PU) is from a thermogram when a sample 10 mg is heated at a heating rate of 10 ° C./min according to JIS K 7121 using DSC-7 manufactured by PerkinElmer. I can confirm.

  The polyester resin (PE) includes a polybasic acid component (g) (hereinafter sometimes referred to as component g), a polyhydric alcohol component (h) (hereinafter sometimes referred to as component h), and In the presence of the compound component (c) (component c) having two or more hydroxyl groups and one or more carboxyl groups in the molecule as described above, or the salt-forming agent (f) (component), and in some cases, copolymerizable The resin obtained by coexisting the above compound and polycondensation. Component g includes terephthalic acid, isophthalic acid, orthophthalic acid, naphthalenedicarboxylic acid, biphenyldicarboxylic acid, oxalic acid, succinic acid, succinic anhydride, adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, hydrogenated dimer acid, Fumaric acid, maleic acid, maleic anhydride, itaconic acid, itaconic anhydride, citraconic acid, citraconic anhydride, dimer acid, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid 2,5-norbornene dicarboxylic acid and its anhydride, tetrahydrophthalic acid and its anhydride, 5-sodium sulfoisophthalic acid, 5-hydroxyisophthalic acid and the like. The polybasic acid component (g) component may be a single type or a mixture of two or more types.

  Instead of a part of the component g, a trifunctional or higher polyfunctional basic acid (g1) or another copolymerizable compound (g2) can be used. Trifunctional or higher polyfunctional basic acid (g1) includes trimellitic acid, pyromellitic acid, benzophenone tetracarboxylic acid, trimellitic anhydride, pyromellitic anhydride, benzophenone tetracarboxylic acid anhydride, trimesic acid, Examples thereof include ethylene glycol bis (anhydro trimellitate), glycerol tris (anhydro trimellitate), 1,2,3,4-butanetetracarboxylic acid and the like. The usage amount of the trifunctional or higher polyfunctional basic acid (g1) is 10 mol% or less with respect to the total usage amount of the polybasic acid component (g).

  Examples of the other compound (g2) copolymerizable with the component a include hydroxycarboxylic acid and ester-forming derivatives thereof. Specifically, fatty acids such as lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, and ester-forming derivatives thereof, benzoic acid, p-tert-butylbenzoic acid, cyclohexane acid, 4 -High boiling point monocarboxylic acids such as hydroxyphenyl stearic acid, high boiling point monoalcohols such as stearyl alcohol and 2-phenoxyethanol, hydroxycarboxylic acids such as ε-caprolactone, lactic acid, β-hydroxybutyric acid, p-hydroxybenzoic acid, Examples thereof include ester-forming derivatives thereof. The usage-amount of the other compound (g2) which can be copolymerized is 10 mol% or less with respect to the total usage-amount of a polybasic acid component (g).

  Examples of the polyhydric alcohol component (h) include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1, 9-nonanediol, 2-methyl-1,3-propanediol, neopentyl glycol, 2,2-diethyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2-methyl-3- Methyl-1,5-pentanediol, 2-methyl-2-ethyl-1,3-propanediol, 2-ethyl-2-butyl-1,3-propanediol, 1,4-cyclohexanedimethanol, bisphenol A and 2,2-bis (4-hydroxyethoxyphenyl) propane, 2,2-bis (4-hydroxyethoxyphenyl) meta 2,2-bis (4-hydroxyethoxyphenyl) ethane, 2,2-bis (3-methyl-4-hydroxyethoxyphenyl) propane, 2,2-bis (3,5-dimethyl-4-hydroxyethoxy) Phenyl) propane, 2,2-bis (4-hydroxyethoxyphenyl) hexafluoropropane, 4,4′-hydroxybenzophenone, bis (4-hydroxyphenyl) sulfoxide called bisphenol S, bis (4-hydroxyphenyl) Glycols having a bisphenol structure obtained by adding one to several moles of ethylene oxide or propylene oxide to two phenolic hydroxyl groups of bisphenols such as sulfides, diethylene glycol, triethylene glycol, dipropylene glycol, poly Ji glycol, polypropylene glycol, and polytetramethylene glycol. Further, it may be a branched aliphatic glycol, and examples of the branched aliphatic glycol include neopentyl glycol. The polyhydric alcohol component (h) may be a single type or a mixture of two or more types.

  Instead of part of the component h, a trifunctional or higher polyhydric alcohol (h1) can be used. Examples of the trifunctional or higher polyhydric alcohol (h1) include glycerin, trimethylolethane, trimethylolpropane, and pentaerythritol. The amount of the trifunctional or higher polyhydric alcohol (h1) used is 10 mol% or less with respect to the total amount of the polyhydric alcohol component (h) used. Among the polyhydric alcohol components (h), ethylene glycol and neopentyl glycol are inexpensive because they are industrially mass-produced, and the various performances of the resin sheet are balanced. Neopentyl glycol is particularly preferred because it improves the chemical resistance of the coating and improves the weather resistance of the resin sheet.

  Compound component (b) (component b) having two or more hydroxyl groups and one or more carboxyl groups in the molecule imparts hydrophilicity to the polyester resin by being contained in the molecular chain of the polyester resin (PE). Can do. Component c is the same as that described as the raw material for producing the urethane resin. The usage-amount of the component c is 20 mol% or less with respect to the total amount of the component g, the component h, the component c, and the component f used for polyester resin manufacture. The salt forming agent (f) is the same as that described as the raw material for producing the urethane resin. The amount of component f used is 20 mol% or less with respect to the total amount of component g, component h, component b, and component f used for producing the polyester resin.

  In order to produce the polyester resin emulsion (PEE), in the polycondensation system, in addition to the polybasic acid component (g) and the polyhydric alcohol component (h), in the presence of component c and component f, an organic solvent In the presence or absence of water, a chain extender or a polymerization terminator is added as necessary, and polycondensed to produce a polyester resin (PE), neutralized with a base, and then an organic solvent is removed if necessary. To obtain a polyester resin emulsion (PEE). Since it has a hydrophilic carboxyl group in the molecular chain of the polyester resin (PE) and itself exhibits water solubility or water dispersibility, it can be called a self-emulsifying emulsion. The carboxyl group contained in the molecular chain can be confirmed by analytical methods such as IR method and NMR method.

The polyester resin (PE) has a glass transition temperature (hereinafter referred to as Tg) in the range of 20 to 90 ° C. When Tg is lower than 20 ° C, the water resistance of the adhesive layer B is inferior, and when it exceeds 90 ° C, the adhesion with the B layer is inferior. Since the B layer is covered with the C layer, the water resistance of the B layer means water immersion from the end face of the resin sheet-coated metal plate. When the water temperature rises, the water resistance is inferior and easily peels off. From the viewpoint of the balance between adhesiveness and workability, a more preferable range of Tg is 40 to 80 ° C. In the present invention, the glass transition temperature of the polyester resin was determined by using DSC-7 manufactured by Perkin Elmer, and 10 mg of the sample in JIS.
According to K7121, the temperature measured by a thermogram when the temperature is raised at a heating rate of 10 ° C./min.

  The polyester resin (PE) has a number average molecular weight in the range of 4,000 to 18,000. In the present invention, the number average molecular weight means a value measured by GPC (gel permeation chromatography) method and converted to polystyrene. If the number average molecular weight is less than 4,000, adhesion and workability tend to be insufficient. The number average molecular weight is preferably 6,500 or more, and particularly preferably 8,000 or more. When the number average molecular weight exceeds 18,000, the viscosity when this resin is emulsified becomes too high, which is not preferable.

  The polyester resin (PE) has an acid value in the range of 5 to 25 mgKOH / g. In the present invention, the acid value of the polyester resin (PE) is determined by dissolving 0.5 g of a polyester resin in 50 m of a mixture of water and dioxane in a volume ratio of 10 to 1, and titrating with KOH using cresol red as an indicator. The value obtained by converting the number of mg of KOH consumed for neutralization per gram of the polyester resin was calculated as the acid value. When the acid value is less than 5 mgKOH / g, it is difficult to disperse the polyester resin (PE) in the aqueous medium, and when it exceeds 25 mgKOH / g, the water resistance of the adhesive layer is inferior, and the adhesiveness and workability are insufficient. Tend to. Polyester resin (PE) is one in which hydroxyl groups are introduced within a range that does not impair the advantages of polyester resin, such as processability and adhesion to the substrate, for the purpose of increasing the reactivity with the curing agent. It may be. In that case, the upper limit of the hydroxyl value is preferably 20 mgKOH / g, more preferably 15 mgKOH / g or less, further preferably 10 mgKOH / g or less, and particularly preferably 5 mgKOH / g or less.

  In the resin sheet-covered metal plate according to the present invention, two layers of an adhesive layer B and an adhesive layer C are provided on the surface of the metal plate A. As described above, in the adhesive layer B, the component constituting the adhesive layer B is an adhesive layer formed from a self-emulsifying urethane resin emulsion (PUE). Adhesive layer C is an adhesive layer formed from a mixture of self-emulsifying urethane resin emulsion (PUE) 10-40% by mass (solids) and polyester resin emulsion (PEE) 90-60% by mass (solids). It is. When the adhesive layer C is a single layer formed of PEE, the adhesiveness with the thermoplastic resin sheet (D) laminated and adhered to the adhesive layer C is sufficient, but the secondary layer is accompanied by deformation of the metal plate. When (after) processing, for example, shearing, punching, bending, drawing, or the like is performed, there is a disadvantage that the resin sheet peels from the metal plate. On the other hand, in the B layer alone, the adhesion to the metal plate A and the adhesion to the PVC sheet are good, but the adhesion to the polyester resin sheet is not sufficient, and as in the case of the C layer alone, (After) When processing, inconvenience such as peeling of the resin sheet occurs. In the present invention, the deformation resistance, which tends to be inferior with the B layer alone, is compensated by making it into the C layer and the two layers.

  C layer is comprised by the mixture which consists of polyester resin emulsion (PEE) 90-60 mass% (solid content) and urethane resin emulsion (PUE) 10-40 mass%. When the polyester resin emulsion (PEE) of the C layer exceeds 90% by mass, the adhesiveness to the B layer is poor, and when it is less than 60% by mass, the adhesiveness to the thermoplastic resin sheet (D) is poor. Become.

  A curing agent (E) is blended in the adhesive forming the B layer and the C layer. The curing agent (E) imparts reactivity to the B layer and the C layer. Examples of the curing agent (E) include a compound (D1) having an isocyanate group, a compound (E2) having a carbodiimide group, and a compound (E3) having two or more oxazoline groups in one molecule. The curing agent (E) is used as a mixture of two or more of those exemplified.

  The compound (E1) having an isocyanate group is the same as the compound exemplified for the production of the polyurethane resin (PU). The compound (E2) containing a carbodiimide group reacts with the carboxyl group contained in the polyester resin emulsion (PEE) or the resin contained in the urethane resin emulsion (PUE), and the adhesive composition is cured. A cross-linked structure is formed on the surface to improve the interfacial adhesion between the B layer and the C layer. The compound (E2) containing a carbodiimide group may be a compound having two or more carbodiimide groups in one molecule and may be a polycarbodiimide having water solubility or water dispersibility. Examples of such carbodiimide compounds include those having a hydrophilic group at the terminal. This is produced by, for example, forming an isocyanate-terminated polycarbodiimide by a condensation reaction involving decarbonization of an organic diisocyanate compound, and then adding a hydrophilic segment having a functional group having reactivity with an isocyanate group. can do. These carbodiimide compounds are aqueous solutions and emulsion types of water-soluble carbodiimide resins from Nisshinbo under the trade names Carbodilite E02, E04, V02, V04, from Nikka Chemical Co., Ltd. under the trade name NK Assist CI. It is commercially available and can be easily obtained.

  The compound (E3) having an oxazoline group reacts with a carboxyl group contained in a resin contained in a polyester resin emulsion (PEE) or a urethane resin emulsion (PUE) to crosslink between the resins when the adhesive composition is cured. A structure is formed to improve the interfacial adhesion between the B layer and the C layer. As the compound (E3) having an oxazoline group, an aqueous solution of a water-soluble oxazoline resin or an emulsion type oxazoline resin (an oxazoline resin emulsion) is available from Nippon Shokubai Co., Ltd. under the trade names of Epocross WS700, WS500, K1020E. It is commercially available from Kagakusha under the trade name NK Assist OX and is readily available.

  The amount of the curing agent (E) to be blended (contained) in the adhesive forming the B layer or the C layer is to improve the adhesiveness and workability with respect to the carboxyl group contained in the B layer or the C layer. Thus, an amount corresponding to 1 to 5 equivalents of an isocyanate group, an oxazoline group or a carbodiimide group is preferable. The number of moles of the carboxyl group contained in the polyester resin (PE) is calculated from the mass and the acid value of the polyester resin (PE). The number of moles of the carboxyl group contained in the polyurethane resin (PU) is calculated from the number of moles of the isocyanate compound.

  The mixing ratio of the curing agent (E) to the adhesive (solid content) composed of the polyester resin emulsion (PEE) and the polyurethane resin emulsion (PUE) can be appropriately selected depending on the thickness and performance of the target resin film. In order to keep the viscosity of the adhesive moderate and to exhibit a good film forming ability, a compound having an isocyanate group (E1), a compound having a xazoline group (E2), and a compound having a carbodiimide group (E3) The amount is preferably 5 to 40% by mass, and 8 to 30% by mass when the total amount of the solids contained in the adhesive forming the B layer or C layer and the curing agent (E) is 100% by mass. More preferred.

  Moreover, a curing catalyst (j) can be mix | blended with the hardening | curing agent (E) of this invention as needed. Preferable curing catalysts (j) include tin-based curing catalysts such as di-n-butyltin dilaurate, tetra-n-butyltin, and tetramethylbutanediamine. Moreover, a silane coupling agent (k), a titanium coupling agent (m), etc. can be mix | blended for the further improvement of performance. The compounding quantity of a curing catalyst (j) can be selected in the range of 0.01-10.0 mass parts with respect to 100 mass parts of hardening | curing agents (E).

  Examples of the thermoplastic resin forming the thermoplastic resin sheet (E) in the present invention include PVC, polyester resin, polyamide resin, polyolefin resin, and polycarbonate. Of these, PVC and polyester resins are preferred. If these thermoplastic resin sheets are too thin, it will be difficult to laminate, and if they are too thick, the secondary processing of the resin sheet-coated metal plate cannot be performed smoothly, and cracks may occur on the sheet surface. It is not preferable because it peels off. A preferable sheet thickness is in the range of 100 to 300 μm.

  PVC may be hard, semi-rigid or soft. In order to make PVC semi-rigid or soft, a plasticizer may be added to PVC. Examples of the plasticizer include dioctyl phthalate (DOP), dibenzyl phthalate, dibutyl phthalate, butyl benzyl phthalate, and dibutyl fumarate. The amount of the plasticizer is up to 50 parts by mass with respect to 100 parts by mass of the resin.

  Polyester resins include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene isophthalate (PEI), polyethylene naphthalate (PEN), and a polyethylene terephthalate / ethylene isophthalate copolymer (PETI) mainly composed of ethylene terephthalate units. ), Polybutylene terephthalate isophthalate copolymer (PBTI), polytrimethylene terephthalate) (PTT), polycyclohexanedimethanol-co-ethylene terephthalate (PETG), polybutylene naphthalate (PBN), and the like. These may be one kind or a mixture of two or more kinds.

  Hereinafter, the manufacturing method of the resin sheet coating | coated metal plate which concerns on this invention is demonstrated. First, a urethane resin emulsion (PUE) is applied to the metal plate A, and the adhesive layer B is formed by heating and drying. The heating temperature at this time can be selected in the range of 150 to 300 ° C. Next, a polyester resin emulsion (PEE) is applied, heated and dried to form an adhesive layer C. If the heating temperature in this case can be selected in the range of 150 to 300 ° C., and the heating temperature is less than 150 ° C., the adhesion strength may be too weak and the reflective film may peel off. On the other hand, when the temperature is higher than 300 ° C., the adhesive is thermally deteriorated and the adhesion strength is lowered, which causes the resin sheet to be cracked or peeled off due to impact during processing. The adhesive can be applied by a conventionally known method such as an airless method, spray coating, dipping method, gravure coating, roll coating method, bar coating, or brush coating method. The adhesive is preferably applied so that the thickness after drying is 0.5 to 10 μm, particularly 1 to 5 μm.

  Next, the metal plate coated with the adhesive is heated, the thermoplastic resin sheet (D) is stacked and transferred between the nip rolls, and the adhesive is applied to the thermoplastic resin sheet (D). Any method of pressure bonding a heated metal plate to the adhesive side may be used. The thermoplastic resin sheet (D) may be any of a smooth sheet, a sheet having an embossed pattern, a laminated sheet in which a colored sheet and an embossed sheet are laminated. It may be a high-design sheet that combines a colored sheet containing an iris pigment and a transparent sheet with an embossed pattern.

  EXAMPLES Hereinafter, although this invention is demonstrated further more concretely based on an Example, this invention is not limited to the example as described below. The characteristics of the polyester resin emulsion (PUE) and urethane resin emulsion (PUE) used in the following examples are as described below. The thermoplastic resin sheet laminated on the surface of the metal plate A via an adhesive layer is prepared by the method described below.

[Curing agent and coupling agent]
(1) Curing agent 1: a compound having an isocyanate group (manufactured by Nikka Chemical Co., Ltd., trade name: NK assist NY).
(2) Curing agent 2: A compound having a carbodiimide group (manufactured by Nisshinbo Co., Ltd., trade name: Carbodilite E02).
(3) Curing agent 3: A compound having an oxazoline group (manufactured by Nippon Shokubai Co., Ltd., trade name: Epocross WS50).
(4) Coupling agent: 3 aminopropyltrimethoxysilane (GE Toshiba Silicone, silane coupling agent A1100).

[Preparation of PVC sheet]
30 parts by mass of DOP as a plasticizer, 20 parts by mass of di-n-octyltin bis (isooctyl thioglycolate) salt as a plasticizer and 5 parts by mass of titanium white as a pigment with respect to 100 parts by mass of PVC having a polymerization degree of 1000 A portion was weighed and mixed with a super mixer. The obtained mixture was kneaded by an 18-inch roll set at a temperature of 130 ° C. to prepare a soft PVC sheet having a thickness of 150 μm.

[Preparation of polyester resin sheet]
Mixture 100 of 60% by mass of polybutylene terephthalate (Mitsubishi Engineering Plastics, trade name: Novaduran 5020S) and 40% by mass of polyethylene terephthalate (Eastman Chemical Company, trade name: Easter PET-G · 6763) 100 Part by weight, 3 parts by weight of titanium white as a pigment, and 2 parts by weight of titanium yellow were weighed and mixed by a tumbler mixer. The mixture was extruded as a sheet having a thickness of 200 μm using an extruder equipped with a T die at the tip (Technobel, model: K-25-25T, L / D = 25) at a cylinder temperature of 260 ° C. A casting roll engraved with an abstract embossed pattern of 85 μm in maximum height (Ry) is placed on the melt die extrusion side of the T die, and the embossed pattern is transferred to the surface of the sheet extruded from the T die. The polyester resin sheet with the embossed pattern on the surface was prepared.

[Example 1 to Example 5, Comparative Example 1 to Comparative Example 11]
[Preparation of PVC sheet-coated metal sheet]
An emulsion is selected from the emulsions shown in Tables 1 and 2 (the numerical values in the table mean parts by mass of solids), and the types and amounts of curing agents shown in Tables 3 and 4 are used. (Parts by mass) and a silane coupling agent (parts by mass) were weighed and mixed uniformly to prepare an adhesive. These adhesives are first applied to the surface of a hot dip galvanized steel sheet having a thickness of 0.45 mm and a width of 20 cm by applying a urethane resin emulsion (PUE) by a roll coating method to a coating thickness of 2 μm after drying. It was applied and dried at 80 ° C. to form a B layer. On this B layer, the said polyester resin emulsion (PEE) was apply | coated so that the coating thickness after drying might be set to 2 micrometers by the roll-coating method, and it was made to dry at 80 degreeC, and formed C layer. After that, the temperature was set to 200 ° C., sandwiched between a pair of laminate rolls having a diameter of 7 cm and a length of 35 cm, set to 200 ° C., then taken up with a take-up roll while being heated in a heating furnace, cooled to room temperature, A PVC sheet-coated metal plate was prepared.

[Evaluation of PVC sheet-coated metal sheet]
The obtained PVC sheet-coated metal plate was evaluated by the following procedure, and the evaluation results are shown in Table-3 and Table-4.
(A) Initial peel strength (N / 20 mm): A test piece having a size of 30 mm × 120 mm was cut from the PVC sheet-coated metal plate prepared by the above method. A cut was provided in the PVC sheet of the test piece so that the PVC sheet had a width of 20 mm along the length direction and reached the surface of the metal plate. One end of a PVC sheet with a width of 20 mm sandwiched between the cuts is forcibly separated from the metal plate, the edge of the peeled PVC sheet is grasped by one clamp of the tensile tester, and the metal plate is grasped by the other clamp of the tensile tester. {The resin sheet is peeled from the surface of the metal plate in a direction of 180 degrees (opposite direction). } A peel test was performed under the condition of a peel rate of 50 mm / min. The maximum strength at this time was displayed as peel strength (unit: N). A larger value means that the resin sheet is more difficult to peel from the metal plate. Also, those having a peel strength of 50 N / 20 mm width or more, ◎, those having a width of less than 40-50 N / 20 mm, ◯, those having a width of less than 30-40 N / 20 mm, Δ, those having a width of less than 30 N / 20 mm, and displayed.

(B) Strength after immersion in hot water (N / 20 mm): A test piece having a size of 30 mm × 120 mm was cut out from the resin sheet-coated metal plate prepared by the above method, and this test piece was immersed in boiling water for 5 hours. Pulled up. For this test piece, the peel strength of the resin sheet from the metal plate was measured and displayed as the peel strength (unit: N) in the same procedure as in (1) above. The larger this value, the better the adhesion after immersion in hot water, and the better the water resistance at the same time. In addition, ◎ to × determined based on the same criteria as the above (a) are also displayed.

(C) Peel strength after processing (N / 20 mm): A resin sheet-coated laminated ridge prepared by the same method as in (1) above was cut into a 30 mm × 120 mm size test piece. Draw two lines perpendicular to the length direction at an interval of 50 mm at the center of the length direction of the test piece, hold both ends in the length direction of the test piece with clamps of a tensile tester, The film was stretched in a uniaxial direction until the distance between them became 60 mm. The stretched test piece was used as a sample, and a cut was provided in the resin sheet between the spread lines so as to reach the metal plate so as to have a width of 20 mm, as in (a) above. One end of the resin sheet provided with the cut was forcibly peeled, and the peel strength was measured in the same manner as in (a) above. The larger this value, the better the adhesion after bending and drawing. In addition, ◎ to × determined based on the same criteria as the above (a) are also displayed.

(D) Comprehensive evaluation: Comprehensive evaluation: By combining the evaluation items (a) to (c) above, ◎ is very good, ○ is slightly problematic but there is no practical problem, and practical problem is Some were marked with x.

The following becomes clear from Table-3 and Table-4.
1. The PVC sheet laminated metal plate of the example of the present invention has excellent initial peel strength, peel strength after immersion in hot water, and peel strength after secondary processing, and has excellent adhesion to the metal plate (Example 1 to Example 1). See Example 5).
2. Even if the adhesive is an adhesive consisting of a polyester resin emulsion (PEE) alone (Comparative Example 1) or an adhesive consisting of two layers of a B layer and a C layer, the A layer is a polyester resin emulsion (PEE). In the adhesive (comparative example 2) which consists of these alone, adhesiveness with a PVC sheet is not enough.
2. Even if the adhesive layer is composed of two layers of the B layer and the C layer, when the ratio of the urethane resin emulsion (PEE) of the B layer is small, the adhesiveness with the PVC sheet is not sufficient (Comparative Example 3, Comparison) See Example 4 and Comparative Example 5).
3. Even if the adhesive layer is composed of two layers of the B layer and the C layer, when the acid value of the polyester resin contained in the polyester resin emulsion (PEE) forming the C layer does not satisfy the requirements of claim 1, Adhesiveness with the PVC sheet is not sufficient (see Comparative Example 8, Comparative Example 9 and Comparative Example 10).
4). Even if the adhesive layer is composed of two layers of the B layer and the C layer, if the glass transition temperature of the urethane resin emulsion (PUE) forming the B layer does not satisfy the requirement of claim 1, Adhesion is not sufficient (see Comparative Example 11).

[Example 6 to Example 10, Comparative Example 12 to Comparative Example 22]
[Preparation of polyester resin sheet-coated metal sheet]
Emulsions of the types shown in Table-1 and Table-2 (the numbers in the table mean parts by mass of solids) are selected, and the curing agent (parts by mass) and silane coupling agent (parts by mass) are shown in Table-3. And the adhesive which mixed the kind and quantity which were shown in Table-4 was prepared. These adhesives are first applied to the surface of a hot-dip galvanized steel sheet (same type as used in Example 1) with a urethane resin emulsion (PUE) by a roll coating method so that the coating thickness after drying is 2 μm. It was applied and dried at 80 ° C. to form a B layer. On this C layer, the said polyester resin emulsion (PEE) was apply | coated so that the application | coating thickness after drying might be set to 2 micrometers by the roll coat method, and it dried at 80 degreeC, and formed C layer. Then, the temperature was set to 240 ° C., sandwiched between a pair of laminate rolls having a diameter of 7 cm and a length of 35 cm, set to 240 ° C., then taken up with a take-up roll while being heated in a heating furnace, cooled to room temperature, A polyester resin sheet-coated metal plate was prepared.

[Evaluation of polyester resin sheet-coated metal sheet]
The obtained polyester resin sheet-covered metal plate was evaluated by the following procedure, and the evaluation results are shown in Table-5 and Table-6.
(A ′) Initial peel strength (N / 20 mm): The test method is the same as the method described in (a) above. Also, those having a peel strength of 80 N / 20 mm width or more are ◎, those having a width of less than 60 to 80 N / 20 mm are ◯, those having a width of less than 50 to 60 N / 20 mm are Δ, those having a width of less than 50 N / 20 mm are displayed.
(B ′) Strength after immersion in hot water (N / 20 mm): The test method is the same as the method described in (b) above. Also, those having a peel strength of 60 N / 20 mm width or more, ◎, those having a width of less than 40-60 N / 20 mm, ◯, those having a width of less than 30-40 N / 20 mm, Δ, those having a width of less than 30 N / 20 mm, and displayed.
(C ′) Peel strength after processing (N / 20 mm): The test method is the same as the method described in (c) above. Also, the peel strength of 50N / 20mm width or more is judged as ◎, the one less than 40-50N / 20mm width is ◯, the one less than 30-40N / 20mm width is △, and the one less than 30N / 20mm width is judged as x. did.
(D ′) Comprehensive evaluation: The evaluation items (a ′) to (c ′) are comprehensively evaluated, ◎ being very good, ○ being slightly problematic but having no practical problem, ○ being practically problematic Some were marked with x.

From Table-5 and Table-6, the following becomes clear.
1. The polyester resin sheet laminated metal plate of the example of the present invention has excellent initial peel strength, peel strength after immersion in hot water, and peel strength after secondary processing, and excellent adhesion to the metal plate (Example 6). To Example 10).
2. Even if the adhesive is an adhesive consisting of a polyester resin emulsion (PEE) alone (Comparative Example 12) or an adhesive consisting of two layers of a B layer and a C layer, the A layer is a polyester resin emulsion (PEE). In the adhesive (comparative example 13) which consists of these only, adhesiveness with a polyester resin sheet is not enough.
3. Even if the adhesive layer is composed of two layers, the B layer and the C layer, if the ratio of the urethane resin emulsion (PUE) in the B layer increases, the adhesion of the polyester resin sheet laminate tends to decrease ( Comparative Examples 17 and 18)
4). Even if the adhesive layer is composed of two layers of the B layer and the C layer, when the acid value of the polyester resin contained in the polyester resin emulsion (PEE) forming the C layer does not satisfy the requirements of claim 1, Adhesion with the polyester resin sheet is not sufficient (see Comparative Example 19, Comparative Example 20, and Comparative Example 21).
5. Even if the adhesive layer is composed of two layers of the B layer and the C layer, when the glass transition temperature of the urethane resin emulsion (PUE) forming the B layer does not satisfy the requirements of claim 1, Is not sufficient (see Comparative Example 22).

  Since the highly designable laminated sheet-covered metal plate according to the present invention is excellent in secondary workability, it can be used for building interior materials such as door materials, partition materials, general wall materials, and ceiling materials, OA equipment housings, and electric refrigerators. It is suitable for uses such as a case and a case of a washing machine. Moreover, since it does not cause a problem in the boiling water immersion test, it can also be used for unit bath wall materials and unit bath ceiling materials.

Claims (4)

On at least one side of the metal plate (A), an adhesive layer B composed of the following component (B) is formed, and on this adhesive layer B, the following component (B) is 10 to 40% by mass (solid content), The adhesive layer C consisting of a mixture of 90 to 60% by mass (solid content) of the following (C) component is formed, and the thermoplastic resin sheet (D) is laminated on the surface of the adhesive layer C. A metal sheet coated with a resin sheet.
Component (B): Self-emulsifying urethane resin emulsion (PUE) containing urethane resin (PU) having a glass transition temperature of −65 to −10 ° C.
Component (C): Self-contained polyester resin (PE) having a glass transition temperature of 20 to 90 ° C., a number average molecular weight of 4,000 to 18,000, an acid value of 5 to 25 mg KOH / g, and having a hydrophilic group Emulsion type polyester resin emulsion (PEE).   One or more curing agents (E) selected from the group consisting of a compound having an isocyanate group, a compound having a carbodiimide group, and a compound having an oxazoline group, both in the component (B) and the component (C) The resin sheet-covered metal plate according to claim 1, which is an adhesive layer by containing a).   The resin sheet-covered metal plate according to claim 1 or 2, wherein the thermoplastic resin sheet (E) is a polyvinyl chloride resin sheet or a polyester resin sheet.   The resin sheet-coated metal plate according to any one of claims 1 to 3, wherein the thermoplastic resin sheet (E) is a highly designable sheet.