JP2010253942A - Double-layer film-coated metal plate and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thin film-coated metal plate superior in scratch resistance, abrasion resistance, corrosion resistance and working adherability. <P>SOLUTION: The double-layer-coated metal plate includes a lowermost layer film in contact with the metal surface which is a film obtained by applying a thermally film-forming type aqueous resin coating onto the surface of the metal, which comprises the resin coated with an aqueous resin on the surface of the metal, and further its derivative resin expressed by formula (I), each resin in a predetermined amount; and an outermost layer film which is a film containing a high hardness resin and silica fine particles each in a predetermined amount. In the formula, Z- is a hydrocarbon chain; [A1-Z] shows that A1 and Z covalently bond through functional groups thereof; -X group is a 1-3C hydrolyzable alkoxy group, hydrolyzable halogeno group or hydrolyzable acetoxy group; and a+b+c+d=3. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention is applied to a metal plate of a water-based resin paint, a corrosion-resistant, high-working adhesion bottom layer film produced by heat drying, and after application and drying of the water-based resin paint, ultraviolet irradiation, electron beam irradiation, high temperature heating, etc. At least a part of the surface is covered with a multi-layer film including a scratch-resistant, abrasion-resistant outermost layer film mainly composed of a high-hardness resin obtained by curing with scratch resistance, abrasion resistance, The present invention relates to a multilayer coating-coated metal plate excellent in all of corrosion resistance and work adhesion, and a multilayer coating forming method for the multilayer coating-coated metal plate.

Hereinafter, the background art of the present invention will be described.
"UV curable resin", "UV curable resin paint", "UV cured film", "electron beam curable resin", "electron beam curable resin paint", "electron beam" The “cured film”, “heat-deposited resin”, “heat-deposited resin paint”, “heat-deposited film”, “nonvolatile component”, and “highly hard resin” will be described. The term “ultraviolet curable resin” means an ultraviolet curable resin or a polymerizable hydrocarbon that begins polymerization or crosslinking upon irradiation with ultraviolet rays that are electromagnetic waves, and a resin composition before ultraviolet curing, The term “ultraviolet curable resin paint” means a paint mainly composed of non-volatile components by the “ultraviolet curable resin”, and the term “ultraviolet curable film” means that the “ultraviolet curable resin paint” It means a film after UV curing, obtained by irradiating the surface with UV light after coating, drying. Further, in this specification, “heat-deposited resin” refers to a thermosetting resin, a thermoplastic resin, or a polymerizable hydrocarbon that forms a film by promoting polymerization by a polymerization or crosslinking reaction by heating. The term “heated film-forming resin paint” means a paint mainly composed of a non-volatile component in the “heat-film-forming resin”, "Means a film obtained by applying the above-mentioned" heat-deposited resin paint "to the surface to be coated and drying by heating. Further, in this specification, the “electron beam curable resin” means an electron beam curable resin or a polymerizable hydrocarbon that starts polymerization or cross-linking by absorption of an electron beam that is a particle beam. It means a resin composition before wire curing, and “electron beam curable resin coating” means a coating mainly composed of non-volatile components with the above “electron beam curable resin”. "Means a coating after electron beam curing, obtained by applying the above-mentioned" electron beam curable resin coating "to a coated surface, drying, and then irradiating with an electron beam. In the present specification, the “nonvolatile content” means a component remaining after volatilizing a low molecular weight compound (such as water or a solvent) blended as a solvent in a paint or a composition. The “highly hard resin” is a resin that has been highly crosslinked and hardened by irradiating ultraviolet rays to the “ultraviolet curable resin”, and irradiating an electron beam to the “electron beam curable resin”. Highly cross-linked and hardened resin, the above-mentioned “heat-deposited resin” is heated to 200 ° C. or higher at a high temperature, highly cross-linked and hardened resin, or highly cross-linked by other cross-linking methods, It means a hardened resin. The surface coating treatment of metal plates with UV curable resin coatings enables the formation of UV cured films with high molecular weight and highly cross-linked structure by UV irradiation in seconds or less. In some cases, a harder surface can be obtained than a surface coating treatment with a heat-deposited resin coating, and therefore, it is used in various industrial fields for scratch prevention and wear resistance treatment of metal surfaces. Among these UV-curable resin paints, solvent-based paints and solvent-free paints that impart coating properties by diluting high-viscosity reactive polymers with low-viscosity reactive monomers Recently, water-based and powdery UV-curable resin coatings containing almost no solvent or monomer have been developed, and some have been put on the market.

  Of these solvent-free paints, in the case of metal coating with powder UV curable resin paint, at least (1) electrostatic coating on a metal plate, (2) powder at high temperature Three steps of melting and continuous film formation and (3) curing by ultraviolet irradiation are required, the manufacturing process is complicated, the total equipment cost is high, and thin film coating treatment with a film thickness of 20 μm or less is difficult.

  Also, in the case of metal coating treatment with water-based UV-curable resin paint, three steps of painting, drying and UV irradiation are indispensable, but liquid coating is easier than powder coating and water drying. Since the process does not require high-temperature baking as in powder coating, the equipment and running costs are considerably lower than in powder coating. Furthermore, in metal coating treatment with water-based UV-curable resin paint, thin film coating treatment of micron level, submicron level, or less, which is impossible with powder coating, is industrially possible. It is attracting attention as a method for processing a hard thin film of a metal plate that is low in environmental impact and inexpensive.

  However, even with a coating treatment using a solvent-based, solvent-free, water-based or powder-based UV-curable resin coating, a large number of radicals originating from the photopolymerization initiator are instantaneously generated in the entire coating film irradiated with UV light. Because of high-speed chain reaction, high cross-linking and high-polymerization occur quickly, resulting in large volume shrinkage and residual film distortion after curing. It was insufficient compared with the case of using. Therefore, the ultraviolet-cured film produced on the metal plate is inferior in shielding properties of metal corrosion factors such as oxygen and chloride ions, and has a problem in corrosion resistance, as compared with the film formed by heating.

  To solve such problems, for example, as a method for suppressing shrinkage during curing and improving adhesion to a metal surface in an aqueous ultraviolet curable resin coating, a relatively high molecular weight weight having a number average molecular weight of 1000 to 15000 is used. There has been proposed a method for forming an ultraviolet-cured film having excellent adhesion to a metal using an aqueous dispersion of a reactive resin based on coalescence (see Patent Document 1). In addition, a method of forming a UV-cured film having excellent adhesion to metal or wood using a water-dispersible photopolymerization initiator having a weight average molecular weight of 500 to 2000 is slightly proposed (patent) Reference 2).

  On the other hand, a multilayer coating in which the outermost layer is a UV-cured film and the lower film is a film other than the UV-cured film, as in the film structure of the present invention, instead of a metal plate coated with a single-layer ultraviolet-cured film Several techniques related to metal plates have been proposed. For example, a technique for improving the adhesion of an ultraviolet-cured film by coating an aqueous urethane-based resin base on a metal plate or a surface-treated metal plate and then applying an ultraviolet curable coating on the upper layer is disclosed ( (See Patent Document 3). Further, a three-layer coated metal plate (see Patent Document 4) composed of an ultraviolet-cured resin layer, an acrylic resin layer, and a vinyl chloride resin layer in order from the surface layer has been proposed. As another example, a three-layer coated galvanized steel sheet (see Patent Document 5) composed of a film-forming resin layer, an undercoat film layer, and a chemical conversion film layer using ultraviolet irradiation and heating in order from the surface layer has been proposed.

  The surface coating treatment of metal plates with electron beam curable resin coatings not only enables short-time cross-linking as in the case of UV curing, but also breaks the resin chain with much stronger electron energy than in UV curing. Since radicals can be generated, it is possible to crosslink even a resin in a glass state (resin with a very low molecular chain mobility) that does not require an essential polymerization initiator in the case of UV curing. Excellent features such as unnecessary. Therefore, it is used for preventing scratches on metal surfaces and for anti-wear treatment. However, a large number of radicals are instantaneously generated in the entire coating film that has absorbed the electron beam, and it is quickly crosslinked and polymerized by a high-speed chain reaction, resulting in a large volume shrinkage and residual film distortion after curing. Adhesion to the film and film bulk density were insufficient as compared with the case of using a heat-deposited resin paint. For this reason, the electron beam-cured film formed on the metal plate is inferior in shielding properties of metal corrosive factors such as oxygen and chloride ions, and has a problem in corrosion resistance, as compared with the film formed by heating.

  In response to such problems, for example, between a hard electron beam-cured film and a metal plate, as a softer layer than the electron beam-cured film, the glass transition temperature is 30 ° C. or less and the film elongation is 50% or more (or glass transition). Corrosion-inducing factors that cannot be suppressed simply by providing a thermosetting coating with a temperature of 65 ° C or less and a coating elongation of 30% or more, or a glass transition temperature of 100 ° C or less) and coating with a single-layer electron beam-cured coating ( There have been proposed methods for suppressing corrosion shrinkage due to differences in temperature, coating cracking due to vibration, coating cracking due to flying objects, etc., and improving corrosion resistance (refer to Patent Documents 6, 7, and 8 respectively).

Japanese Patent Laid-Open No. 10-195372 JP 2007-138134 A Japanese Patent Laid-Open No. 10-157007 JP-A-8-58021 JP 2006-334485 A Japanese Unexamined Patent Publication No. 7-251125 JP 7-289987 A JP-A-8-39726

  In Patent Document 1, a high molecular weight reactive resin is used as a main component of an aqueous ultraviolet curable resin coating, and there are fewer radical reactive sites than a coating containing a large amount of reactive monomers and low molecular weight reactive resins. Therefore, even if a rapid ultraviolet curing reaction occurs, a certain degree of curing shrinkage can be suppressed. However, since the mobility of the high molecular weight reactive resin is low in the film before curing, the reaction efficiency between the radical generated by UV irradiation and the reactive resin is low, and the degree of crosslinking and fineness are insufficient. A film with inferior corrosion factor shielding properties was produced, and the corrosion resistance was not as good as that of the heat-formed film. Further, in the method of Patent Document 2, since the initiator in the aqueous ultraviolet curable resin coating is bulky and generates only low mobility radicals upon irradiation with ultraviolet light, the reaction efficiency with the coexisting reactive resin is low. The degree of cross-linking and the fineness are insufficient. For this reason, the film is inferior in the shielding property of the metal corrosion factor, and the corrosion resistance is not as high as that of the heat-formed film.

  The technique of Patent Document 3 is a technique for improving the adhesion of an ultraviolet-cured film that is inferior in adhesion to a metal surface, and does not improve the insufficient corrosion resistance. In addition, since the UV curable paint used in this technology is not water-based, the UV curable paint cannot be wet-on-wet-painted or coated simultaneously in multiple layers without drying the aqueous urethane-based resin base, which is cumbersome. It was a costly painting process. In other words, after water-based urethane-based resin is applied to the base, it is heated once to dry the moisture and heat-cured, and after cooling, a solvent-based or solvent-free UV-curable resin coating is applied to it. It was necessary to go through many steps of heating to volatilize the solvent and finally irradiating with ultraviolet rays, which was not practical.

  Although the ultraviolet curable resin coating used in the examples of Patent Document 4 is not water-based, Patent Document 4 does not specify liquidity such as aqueous, solvent-based, or solvent-free, and is a water-based UV-curable coating. Can also be used. However, the purpose of this technology is to improve the surface hardness and heat discoloration of a metal decorative plate coated with a vinyl chloride resin, and the acrylic resin layer is used for chlorination when the metal plate is used in the vicinity of a heat source such as a lighting fixture. In order to prevent heat discoloration of the vinyl resin layer and the vinyl chloride resin layer was used for imparting design properties, none of the layers improved the corrosion resistance which is insufficient for the UV-cured resin layer. Moreover, since the ultraviolet curable resin coating used in the technique of Patent Document 5 may be either water-based or solvent-based, an aqueous ultraviolet curable paint can also be used, but this technique adds an ultraviolet curable component to the outermost layer. The reason for this was to prevent sagging of the multilayer coating film by wet-on-wet coating or the like, and not to harden the outermost layer film by an ultraviolet curing component.

  In Patent Documents 6 to 8, sufficient scratch resistance is obtained by the electron beam cured film on the outermost layer, and coating film cracking (coating shrinkage due to difference in temperature) is mainly caused by the action of the lowermost thermosetting film. Cracks, coating film cracks due to vibration, coating film cracks due to flying objects, etc.) can be suppressed. However, the thermosetting coating film in the lowermost layer does not show any device that greatly improves the degree of cross-linking and fineness of the film, or a device that combines the film with a suitable rust preventive agent. As a result, the corrosion resistance of such a multilayer coated metal sheet was insufficient.

  As described above, in the conventional technique, a metal plate coated with a film obtained by ultraviolet curing an aqueous ultraviolet curable resin has been obtained, but a coating film having sufficient scratch resistance and corrosion resistance in a single layer. Is not obtained. In addition, even in the multilayer coated metal plate in which the outermost layer is a UV-cured film and the lower layer film is a film other than the UV-cured film, there has been no product having sufficient scratch resistance and corrosion resistance. Therefore, in various industrial fields, as the use of the UV-cured film, which is water-based and has a low environmental impact during coating, and has excellent scratch resistance and abrasion resistance, has expanded, There has been an increasing demand for sufficient corrosion resistance.

  In addition, in the prior art related to electron beam cured coating, sufficient scratch resistance and corrosion resistance are obtained in a multilayer coated metal plate in which the outermost layer is an electron beam cured coating and the lower layer coating is a coating other than the electron beam cured coating. I couldn't find anything that had. The coated metal plate with the outermost layer coated with an electron beam curable coating of water-based electron beam curable paint has not been industrialized yet, unlike the case of ultraviolet ray curable paint, there is no need to add a polymerization initiator. Therefore, it has excellent environmental impact during coating, excellent curability at room temperature unlike UV curable resins, and better scratch resistance and abrasion resistance than UV cured films. It is considered that it can be used in various industrial fields in the future, taking advantage of the fact that it can be coated. As such applications are expanded, the need for not only scratch resistance and wear resistance but also sufficient corrosion resistance and work adhesion is inevitably increased as in the case of UV-cured films.

  A coating obtained by heating a water-based heat-forming resin to a temperature of 200 ° C. or higher to be highly crosslinked or hardened, or a water-based resin using a method other than UV curing, electron beam curing, or heating at a temperature of 200 ° C. or higher. There is no prior art relating to a coated metal plate that has a cross-linked and hardened film on the outermost layer and is excellent in all of scratch resistance, wear resistance, corrosion resistance, and work adhesion.

  The present invention has been made in view of the problems as described above. After application of the water-based resin coating, the present invention has improved abrasion resistance and abrasion resistance obtained by ultraviolet irradiation, electron beam irradiation, high temperature heating at 200 ° C. or higher, and the like. A multi-layer coating coated metal plate with an excellent high-hardness resin coating as the outermost layer and a combination of the bottom coating made of a resin with excellent corrosion resistance and processing adhesion obtained by application of water-based resin paint and drying, and its multi-layer coating coating The present invention relates to a method for forming a multilayer coating on a metal plate.

  As a result of earnest research to achieve the above-mentioned object, the present inventors have found that there is no scratch on the resin surface by any of the dry steel wool sliding test and the wet cleanser sliding test, A multi-layer structure in which a coating consisting mainly of a high-hardness resin with a high hardness that only gives slight, shallow scratches is placed on the outermost layer, and a specific resin with excellent corrosion resistance and work adhesion is placed on the lowermost layer It has been found that if it is formed on a metal surface, a coated metal plate excellent in all of scratch resistance, wear resistance, corrosion resistance, and work adhesion can be obtained.

  The present invention has been completed based on the above knowledge, and specifically, is as follows.

（式中、Ａ１は水性樹脂（ａ１）を金属表面に塗布、加熱乾燥することにより得られる樹脂、また、Ｚ−は炭素原子数１〜９、窒素原子数０〜２、酸素原子数０〜２の炭化水素鎖で、「Ａ１〜Ｚ」の表記は、Ａ１とＺが両者の官能基を介して共有結合していることを示す。また、−Ｏ−はエーテル結合であり、−ＯＨ基は水酸基であり、−Ｘ基は炭素原子数１〜３の加水分解性アルコキシ基、加水分解性ハロゲノ基又は加水分解性アセトキシ基であり、−Ｒ基は炭素原子数１〜３のアルキル基であり、置換基の数を示すａ、ｂ、ｃ、ｄはいずれも０〜３の整数で、かつａ＋ｂ＋ｃ＋ｄ＝３である。）
（２） 前記水性樹脂塗料（ｊ）が水性の紫外線硬化型樹脂塗料（ｂ）であり、かつ、前記高硬質樹脂（Ｊ）が下記一般式（II）に示す紫外線硬化済み樹脂（Ｂ１）であることを特徴とする、複層被覆金属板。

（式中、Ｒａｄは光開裂型重合開始剤の紫外線受光開裂で生成するラジカル（Ｒａｄ・）の付加物であり、−Ｘ¹基は水素原子又はメチル基であり、−Ｙ¹基は炭化水素基であり、−Ｚ¹基は、アニオン型、カチオン型またはノニオン型の親水基または該親水基を持つ炭化水素基である。）
（３）前記水性塗料(ａ)の樹脂成分が、水性エポキシ系樹脂、水性フェノール系樹脂、水性ポリエステル系樹脂、水性ポリウレタン系樹脂、水性(メタ)アクリル系樹脂及び水性ポリオレフィン系樹脂からなる群から選ばれることを特徴とする1種又は2種以上である前記（１）、（２）のいずれかに記載の複層被覆金属板。
（４）前記樹脂(Ａ２)中の−Ｃ−Ｓｉ−Ｏ−結合を形成するSi原子が、前記複層皮膜のうち金属表面に接する最下層の皮膜中に、前記樹脂(Ａ１)と(Ａ２)の合計100質量部に対し０．１〜30質量部含まれることを特徴とする前記（１）〜（３）のいずれかに記載の金属板。
（５）前記最下層皮膜の付着量が０．０１〜３ｇ／ｍ²である前記（１）〜（４）のいずれかに記載の金属板。
（６）前記最下層皮膜が、ポリフェノール化合物（Ｄ）を前記樹脂(Ａ１)と(Ａ２)の合計100質量部に対して１〜１００質量部含有する前記（１）〜（５）のいずれかに記載の金属板。
（７）前記最下層皮膜が、りん酸及びヘキサフルオロ金属酸からなる群より選択される1種又は2種以上の酸成分（Ｅ）を前記樹脂(Ａ１)と(Ａ２)の合計１００質量部に対して０．１〜１００質量部含有する前記（１）〜（６）のいずれかに記載の金属板。
（８）前記へキサフルオロ金属酸が、Ｔｉ、Ｓｉ、Ｚｒ、Ｎｂからなる群より選択される1種又は2種以上の元素を含む前記（７）に記載の金属板。
（９）前記最下層皮膜が、りん酸塩化合物（Ｆ）を前記樹脂(Ａ１)と(Ａ２)の合計100質璽部に対して０．１〜１００質量部含有する前記（１）〜（８）のいずれかに記載の金属板。
（１０）前記りん酸塩化合物（Ｆ）が、カチオン成分としてＭｇ、Ｍｎ、Ａｌ、Ｃａ、Ｎｉからなる群より選択される1種又は2種以上の元素を含む前記（９）に記載の金属板。
（１１）前記最下層皮膜が、Ｓｉ、Ｔｉ、Ａｌ、Ｚｒからなる群より選択される1種又は2種以上の金属の酸化物からなる金属酸化物微粒子（Ｇ）を前記樹脂(Ａ１)と(Ａ２)の合計１００質量部に対して１〜１００質量部含有する前記（１）〜（１０）のいずれかに記載の金属板。
（１２）前記紫外線硬化済み樹脂(Ｂ１)末端のラジカル付加物Ｒａｄが、下記式(Ｒａｄ１)〜(Ｒａｄ１３)のいずれかで示される構造を持つ末端基である、前記（１）、（２）のいずれかに記載の金属板。

（１３）前記紫外線硬化済み樹脂(Ｂ１)の−Ｚ¹基が、水性エポキシ系樹脂、水性ポリエステル系樹脂、水性ポリウレタン系樹脂、水性(メタ)アクリル系樹脂、水性アミノ系樹脂、及び水性シリコーン系樹脂からなる群から選ばれる1種又は2種以上である前記（１）、（２）、（１２）のいずれかに記載の金属板。
（１４）前記紫外線硬化済み樹脂(Ｂ１)の−Ｘ¹基が水素原子で、該樹脂(Ｂ１)が下記一般式（III）に示す構造である（１）、（２）、（１２）、（１３）のいずれかに記載の金属板。

(式中、Ｒａｄは光開裂型重合開始剤の紫外線受光開裂で生成するラジカル(Ｒａｄ・)の付加物であり、−Ｙ¹基は炭化水素基であり、−Ｚ¹基は、アニオン型、カチオン型またはノニオン型の親水基または該親水基を持つ炭化水素基である。)
（１５）前記複層皮膜の最表層皮膜の付着量が０．２〜３g／ｍ²である前記（１）、（２）、（１２）〜（１４）のいずれかに記載の金属板。
（１６）前記複層被覆金属板の表面に対し乾式スチールウール摺動試験を行った後、金属表面に達する深い擦傷が皆無であり、かつ、前記表面の別部位に対し湿式クレンザー摺動試験を行った後、金属表面に達する深い擦傷が皆無であり、かつ、エリクセン加工後の剥離試験による皮膜剥離面積が頂部面積の１０％未満であることを特徴とする（１）〜（１５）のいずれかに記載の複層被覆金属板。
（１７）前記（１）〜（１６）のいずれかに記載の複層皮膜で片面または表裏両面の少なくとも一部が被覆された金属板の製造方法であって、金属板表面に接する最下層から最表層までの各層の皮膜を、含水(ウェット)状態で、順次、または同時に複層被覆する工程(水性塗料のウェット・オン・ウェット塗装または多層同時塗装工程)と、含水状態の複層皮膜の水分や揮発分を同時に加熱乾燥させる乾燥工程と、乾燥後の複層皮膜の最表層皮膜を紫外線または電子線でラジカル重合し成膜する紫外線または電子線照射工程を、列記した順序で含む、複層被覆金属板の製造方法。 (1) A metal plate in which at least a part of the surface is coated with a multilayer film in which two or more layers are laminated, and the lowermost film in contact with the metal surface of the multilayer film is an aqueous heating film forming type A resin (A1) obtained by applying a resin coating (a) to a metal surface and drying by heating; and applying the aqueous resin (a1) to the metal surface and drying by heating in the coating; Furthermore, the derivative | guide_body contains 50-100 mass% of any one or more of resin (A2) shown to the following general formula (I) with the derivative | guide_body in total, and the membrane | film | coat of the outermost layer among the said multilayer membrane | film | coats, A coating obtained by applying a water-based resin paint (j) to the surface of the coating film, drying, and then curing by ultraviolet irradiation, electron beam irradiation, high temperature heating of 200 ° C. or higher, and the like, and a highly rigid resin (J) 50 to 95% by mass of the coating, silica fine particles (C ) And characterized in that it contains 5 to 35 wt% of the coating, multilayer-coated metal sheet.

(In the formula, A1 is a resin obtained by applying an aqueous resin (a1) to a metal surface and drying by heating, and Z- has 1 to 9 carbon atoms, 0 to 2 nitrogen atoms, and 0 to oxygen atoms. In the hydrocarbon chain of 2, the notation of “A1 to Z” indicates that A1 and Z are covalently bonded through the functional groups of both, —O— is an ether bond, and —OH group Is a hydroxyl group, -X group is a hydrolyzable alkoxy group having 1 to 3 carbon atoms, hydrolyzable halogeno group or hydrolyzable acetoxy group, and -R group is an alkyl group having 1 to 3 carbon atoms. And a, b, c, and d indicating the number of substituents are all integers of 0 to 3, and a + b + c + d = 3.)
(2) The aqueous resin paint (j) is an aqueous ultraviolet curable resin paint (b), and the highly rigid resin (J) is an ultraviolet curable resin (B1) represented by the following general formula (II). A multilayer coated metal sheet, characterized in that it is present.

(In the formula, Rad is an adduct of a radical (Rad.) Generated by ultraviolet light-receiving cleavage of a photocleavable polymerization initiator, -X ¹ group is a hydrogen atom or a methyl group, and -Y ¹ group is a hydrocarbon. And the —Z ¹ group is an anionic, cationic or nonionic hydrophilic group or a hydrocarbon group having the hydrophilic group.)
(3) The resin component of the aqueous paint (a) is selected from the group consisting of an aqueous epoxy resin, an aqueous phenol resin, an aqueous polyester resin, an aqueous polyurethane resin, an aqueous (meth) acrylic resin, and an aqueous polyolefin resin. The multilayer coated metal sheet according to any one of (1) and (2), wherein the multilayer coated metal sheet is one type or two or more types.
(4) The resin (A1) and (A2) are formed in the lowermost layer of the multilayer coating in which Si atoms forming —C—Si—O— bonds in the resin (A2) are in contact with the metal surface. The metal plate according to any one of (1) to (3), wherein the metal plate is contained in an amount of 0.1 to 30 parts by mass with respect to 100 parts by mass in total.
(5) The metal plate according to any one of (1) to (4), wherein an adhesion amount of the lowermost layer film is 0.01 to 3 g / m ² .
(6) Any of (1) to (5), wherein the lowermost layer film contains 1 to 100 parts by mass of the polyphenol compound (D) with respect to a total of 100 parts by mass of the resins (A1) and (A2). Metal plate as described in.
(7) The lowermost layer film is composed of one or more acid components (E) selected from the group consisting of phosphoric acid and hexafluorometal acid in a total of 100 parts by mass of the resins (A1) and (A2). The metal plate in any one of said (1)-(6) contained 0.1-100 mass parts with respect to.
(8) The metal plate according to (7), wherein the hexafluorometal acid contains one or more elements selected from the group consisting of Ti, Si, Zr, and Nb.
(9) The above (1) to (1), wherein the lowermost layer film contains 0.1 to 100 parts by mass of the phosphate compound (F) with respect to a total of 100 mass parts of the resins (A1) and (A2). The metal plate according to any one of 8).
(10) The metal according to (9), wherein the phosphate compound (F) contains one or more elements selected from the group consisting of Mg, Mn, Al, Ca, and Ni as a cation component. Board.
(11) The metal oxide fine particles (G) made of an oxide of one or more metals selected from the group consisting of Si, Ti, Al, and Zr are used as the resin (A1). The metal plate in any one of said (1)-(10) which contains 1-100 mass parts with respect to a total of 100 mass parts of (A2).
(12) The ultraviolet-cured resin (B1) terminal radical adduct Rad is a terminal group having a structure represented by any of the following formulas (Rad1) to (Rad13) (1), (2) The metal plate in any one of.

(13) wherein -Z ¹ group of UV cured resin (B1) is an aqueous epoxy resin, aqueous polyester resins, aqueous polyurethane resins, aqueous (meth) acrylic resin, aqueous amino resin, and aqueous silicone The metal plate according to any one of (1), (2), and (12), which is one or more selected from the group consisting of resins.
(14) The ultraviolet-cured resin (B1) has a structure in which —X ¹ group is a hydrogen atom, and the resin (B1) has the structure represented by the following general formula (III) (1), (2), (12), (13) The metal plate in any one of.

(In the formula, Rad is an adduct of a radical (Rad.) Generated by ultraviolet light-receiving cleavage of a photocleavable polymerization initiator, -Y ¹ group is a hydrocarbon group, -Z ¹ group is an anionic type, (It is a cationic or nonionic hydrophilic group or a hydrocarbon group having the hydrophilic group.)
(15) The metal plate according to any one of (1), (2), and (12) to (14), wherein an adhesion amount of the outermost layer film of the multilayer film is 0.2 to 3 g / m ² .
(16) After performing a dry steel wool sliding test on the surface of the multilayer coated metal plate, there is no deep scratch reaching the metal surface, and a wet cleanser sliding test is performed on another part of the surface. Any of (1) to (15), characterized in that there is no deep scratch after reaching the metal surface, and the film peeling area by the peeling test after the Erichsen processing is less than 10% of the top area A multilayer coated metal plate according to any one of the above.
(17) A method for producing a metal plate in which at least a part of one side or both sides of the front and back sides is coated with the multilayer film according to any one of (1) to (16) above, from the lowest layer in contact with the metal plate surface The coating of each layer up to the outermost layer, in a wet (wet) state, sequentially or simultaneously with a multilayer coating (water-based wet-on-wet coating or multilayer simultaneous coating step) and a multilayer coating with a moisture content It includes a drying process in which moisture and volatile components are heated and dried at the same time, and an ultraviolet or electron beam irradiation process in which the outermost layer film of the dried multi-layer film is radically polymerized with ultraviolet light or electron beam to form a film. A method for producing a layer-coated metal sheet.

  ADVANTAGE OF THE INVENTION According to this invention, even if it receives a strong sliding with a hard foreign material, it is hard to be scratched on the surface, it is hard to wear | wear, and the multilayer coating | coated metal plate which is excellent in corrosion resistance and process adhesiveness can be provided. Since the paint for obtaining the multilayer film of the present invention is all water-based, it has low environmental impact, and there is no need for capital investment for solvent recovery equipment and explosion-proofing when using solvent-based paint. is there. Furthermore, in the production of a multi-layer coated metal sheet, a method of coating each layer from the bottom layer to the top layer in contact with the metal surface sequentially or simultaneously in a water-containing state (wet-on-wet coating method or multilayer simultaneous coating). By using the coating method, it is possible to provide a method for easily producing a multi-layer coated metal sheet that is excellent in all of scratch resistance, abrasion resistance, corrosion resistance, and work adhesion. Of the constituent layers of the multilayer coating, the lowermost layer coating is mainly composed of a heat-deposited resin obtained by heat-drying and crosslinking a water-containing coating comprising a water-based heating film-forming resin as a main component, The outermost layer film is highly crosslinked and hardened by drying a water-containing film composed mainly of a water-based high-hardness resin and then irradiating it with ultraviolet rays, electron beams, heating at 200 ° C or higher, or other methods. The main component is a cured resin.

A schematic diagram of a three-layer sliding curtain coater is shown.

  Hereinafter, the present invention will be described in detail. In the present application, “(meth) acrylic resin” means acrylic resin and methacrylic resin, “(meth) acrylic acid” means acrylic acid and methacrylic acid, and “(meth) acrylate” Means acrylate and methacrylate.

<Metal plate>
The metal plate of the present invention is a metal plate having at least a part of the surface coated with a specific multilayer film in which two or more layers are laminated. Only one surface may be coated, or a part of the surface may be coated or the entire surface may be coated. It is excellent in the scratch resistance, wear resistance, corrosion resistance, and work adhesion of the part coated with the multilayer film of the metal plate.

  As a constituent metal of the metal plate, for example, aluminum, titanium, zinc, copper, nickel, steel, and the like are applicable. The components of these metals are not particularly limited. For example, when steel is used, it may be ordinary steel or steel containing additive elements such as chromium. However, when the metal plate of the present invention is used for strong ironing or deep drawing, the type and amount of additive elements and the metal are selected so that they are suitable for strong ironing or deep drawing. What controlled the structure | tissue appropriately is preferable. Moreover, when using a steel plate as a metal plate, the surface may have a coating plating layer, but the type is not particularly limited, and examples of applicable plating layers include zinc, aluminum, cobalt, and tin. And plating made of any one of nickel, alloy plating containing these metal elements, and other metal elements and non-metal elements. In particular, as the zinc-based plating layer, for example, plating made of zinc, alloy plating of zinc and at least one of aluminum, cobalt, tin, and nickel, or various other metal elements and non-metal elements are included. Although zinc-based alloy plating is mentioned, alloy components other than zinc are not specifically limited. The method for forming the plating layer is not particularly limited, and for example, electroplating, electroless plating, hot dipping, vapor phase plating, or the like can be used. The plating method may be either a continuous type or a batch type. In addition, when using steel sheets, post-plating treatments include zero spangle treatment, which is uniform appearance after hot dipping, annealing treatment, which is a modification treatment of the plating layer, temper rolling for surface condition and material adjustment, etc. However, in the present invention, these are not particularly limited, and any of them can be applied.

<Multi-layer coating>
In the present invention, the multi-layer coating covering the metal plate is a multi-functional coating that shares different functions in each layer, and the lowermost layer in contact with the metal surface of the multi-layer coating is made of a heat-deposited resin. The outermost layer of the multilayer coating comprises a highly crosslinked resin and hardened resin by ultraviolet irradiation, electron beam irradiation, high temperature heating of 200 ° C. or higher, or other methods. If it is a laminated structure of two or more layers that can be manufactured industrially by painting with water-based paint, the presence or absence of an intermediate layer film sandwiched between both the outermost layer and the lowermost layer, and the provision of an intermediate layer film The number of layers, composition, and formation method of the multilayer coating on the metal surface are not particularly limited. However, as a simple and efficient method of forming a multilayer coating on the metal surface, the coating of each layer from the lowest layer to the outermost layer in contact with the metal surface is sequentially or simultaneously coated in a wet (wet) state. Process (wet-on-wet coating of water-based paint or multi-layer simultaneous coating process), drying process to dry the moisture and volatile content of each layer film in a water-containing state at the same time, and the outermost layer film of the multilayer film is UV cured, electronic It is preferable to form a film by a laminating method including a film forming process in which the film is polymerized and cured by linear curing, heating at a high temperature of 200 ° C. or higher, and the like in the listed order. Here, wet-on-wet coating is a method of applying a coating solution on a metal plate and then applying another coating solution on top of the solvent-containing (wet) state before the coating solution dries. Then, the solvent of the resulting laminated coating liquid is simultaneously dried and cured to form a film. The multilayer simultaneous coating method is a method in which multiple layers of coating liquid are applied simultaneously on a metal plate in a laminated state using a multilayer slide curtain coder, slot die coater, etc., and then the solvent of the laminated coating liquid is simultaneously dried and cured. It is a method to form a film.

(式中、Ａ１は水性樹脂（ａ１）を金属表面に塗布、加熱乾燥することにより得られる樹脂、また、Ｚ−は炭素原子数１〜７，窒素原子数０〜２，酸素原子数０〜２の炭化水素鎖で、Ａ１〜Ｚの表記は、Ａ１とＺが両者の官能基を介して共有結合していることを示す。また、−０−はエーテル結合であり、−ＯＨ基は水酸基であり、−Ｘ基は炭素数１〜３の加水分解性アルコキシ基又は加水分解性ハロゲノ基であり、−Ｒ基は炭素数１〜３のアルキル基であり、置換基の数を示すa、ｂ、ｃ、dはいずれも０〜３の整数で、かつａ＋ｂ＋c＋ｄ＝３である。) Of the multi-layer coating of the present invention, the lowermost layer in contact with the metal surface is a resin (A1) obtained by applying an aqueous resin (a1) to the metal surface and drying by heating, and derivatives thereof. The resin (A1) or the resin (A2) is contained in an amount of 50 to 100% by mass of the resin (A1) and the resin (A2) in any one of the resins (A2) shown in (I).

(In the formula, A1 is a resin obtained by applying an aqueous resin (a1) to a metal surface and drying by heating, and Z- has 1 to 7 carbon atoms, 0 to nitrogen atoms, and 0 to 0 oxygen atoms. In the hydrocarbon chain of 2, the notation of A1 to Z indicates that A1 and Z are covalently bonded via both functional groups, -0- is an ether bond, and -OH group is a hydroxyl group. The —X group is a hydrolyzable alkoxy group having 1 to 3 carbon atoms or a hydrolyzable halogeno group, the —R group is an alkyl group having 1 to 3 carbon atoms, and a represents the number of substituents; (b, c and d are all integers of 0 to 3 and a + b + c + d = 3)

  The resin (A1) used in the present invention is a resin obtained by preparing an aqueous paint (a) containing 50 to 100% by mass of a non-volatile content of the aqueous resin (a1), applying it to the surface of a metal plate, and drying it.

  Non-volatile components other than the aqueous resin (a1) contained in the aqueous coating material (a) are a cross-linking agent, a silane coupling agent (s), a polyphenol compound (D), phosphoric acid, and hexafluorometal acid as described in detail later. (E), phosphate compound (F), metal oxide fine particles (G) and the like. Since the content of these compounds in the lowermost layer film after film formation has a preferable range with respect to the total mass of the resins (A1) and (A2), as described later, an aqueous paint containing these compounds ( When blending a), the blending amount is adjusted so that these are within the preferable content range in the film after film formation.

  Although there is no restriction | limiting in particular in aqueous resin (a1), The aqueous | water-based epoxy resin, aqueous | water-based phenol resin, aqueous | water-based polyester resin, aqueous | water-based polyurethane resin, aqueous | water-based (meth) acrylic-type widely used for the aqueous chemical conversion treatment of the metal surface One or more selected from the group consisting of a resin and an aqueous polyolefin resin are preferred. In the present invention, the aqueous resin includes a water-soluble resin that is completely dissolved in water and a resin (water-dispersible resin) that is uniformly finely dispersed in water in the form of an emulsion, suspension, or the like. Among the aqueous resins (a1), the aqueous epoxy resin is not particularly limited. For example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, resorcin type epoxy resin, hydrogenated bisphenol A type epoxy resin, hydrogenated bisphenol F Epoxy resin such as epoxy resin, resorcinol type epoxy resin, novolac type epoxy resin, etc., reacted with an amine compound such as diethanolamine, N-methylethanolamine, etc. Examples thereof include those obtained by radical polymerization of a high acid value acrylic resin in the presence of a resin and then neutralized with ammonia or an amine compound to make it water-based.

  Among the aqueous resins (a1), the aqueous phenolic resin is not particularly limited. For example, an aromatic compound such as phenol, resorcin, cresol, bisphenol A, and paraxylylene dimethyl ether and formaldehyde are present in the presence of a reaction catalyst. Examples thereof include those obtained by reacting an addition-reacted phenol resin such as methylolated phenol resin with amine compounds such as diethanolamine and N-methylethanolamine, and neutralizing with an organic acid or inorganic acid to make it aqueous.

  Of the aqueous resin (a1), the aqueous polyester resin is not particularly limited. For example, ethylene glycol, propylene glycol, diethylene glycol, 1,6-hexanediol, neopentyl glycol, triethylene glycol, bisphenol hydroxypropyl ether. , Polyols such as glycerin, trimethylolethane, trimethylolpropane, and phthalic anhydride, isophthalic acid, terephthalic acid, succinic anhydride, adipic acid, sebacic acid, maleic anhydride, itaconic acid, fumaric acid, hymic anhydride, etc. Examples thereof include those obtained by dehydrating polycondensation with a polyvalent carboxylic acid, neutralizing with ammonia or an amine compound, and making it aqueous.

  Of the aqueous resin (a1), the aqueous polyurethane resin is not particularly limited. For example, ethylene glycol, propylene glycol, diethylene glycol, 1,6-hexanediol, neopentyl glycol, triethylene glycol, bisphenol hydroxypropyl ether. , Glycerin, trimethylolethane, trimethylolpropane and other polyols and polyisocyanates such as hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI) and tolylene diisocyanate (TDI) are subjected to a polyaddition reaction. And water-based ones.

  Of the aqueous resin (a1), the aqueous (meth) acrylic resin is not particularly limited, and examples thereof include alkyl (such as ethyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and n-butyl (meth) acrylate). By radical polymerizing (meth) acrylic acid esters such as (meth) acrylate, 2-hydroxyethyl (meth) acrylate and other hydroxyalkyl (meth) acrylates and alkoxysilane (meth) acrylates in water together with (meth) acrylic acid. What can be obtained can be mentioned.

  Of the aqueous resin (a1), the aqueous polyolefin resin is not particularly limited. For example, ethylene and unsaturated carboxylic acids such as methacrylic acid, acrylic acid, maleic acid, fumaric acid, itaconic acid, and crotonic acid are used at high temperature and high pressure. After radical polymerization, ammonia, amine compounds, basic metal compounds such as KOH, NaOH, LiOH, etc. or neutralized with ammonia or amine compounds containing the above metal compounds to make them aqueous can be mentioned. .

  The aqueous resin (a1) for forming the resin (A1) may be used alone or in combination of two or more. Further, as the main component of the water-based paint, one or two or more water-based composite resins obtained by modifying at least one other water-based resin in the presence of at least one water-based resin are water-based resins (a1). ).

  Furthermore, when preparing an aqueous paint containing the aqueous resin (a1), a crosslinking agent for the aqueous resin (a1) may be added, or a crosslinking agent may be introduced into the resin skeleton, if necessary. . The crosslinking agent is not particularly limited, and examples thereof include at least one crosslinking agent selected from the group consisting of amino resins, polyisocyanate compounds, blocked polyisocyanates, epoxy compounds, carbodiimide group-containing compounds, and the like. By blending these cross-linking agents, the cross-linking density of the film and the adhesion to the metal surface can be increased, and the corrosion resistance and work adhesion are improved. These crosslinking agents may be used alone or in combination of two or more.

  The amino resin is not particularly limited, and examples thereof include a melamine resin, a benzoguanamine resin, a urea resin, and a glycoluril resin.

  It does not specifically limit as said polyisocyanate compound, For example, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, tolylene diisocyanate etc. can be mentioned. The blocked polyisocyanate is a blocked product of the polyisocyanate compound.

The epoxy compound is not particularly limited as long as it is a compound having a plurality of epoxy groups (oxirane rings) which are 3-membered cyclic ether groups. For example, adipic acid diglycidyl ester, phthalic acid diglycidyl ester, terephthalic acid diglycidyl Esters, sorbitan polyglycidyl ether, pentaerythritol polyglycidyl ether, glycerin polyglycidyl ether, trimethylpropane polyglycidyl ether, neopentyl glycol polyglycidyl ether, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene Glycol diglycidyl ether, 2,2-bis- (4′-glycidyloxyphenyl) propane, tris (2,3-epoxy Propyl) isocyanurate, bisphenol A diglycidyl ether, and hydrogenated bisphenol A diglycidyl ether and the like. Since many of these epoxy compounds have a glycidyl group in which one —CH ₂ — is added to the epoxy group, the word “glycidyl” is included in the compound name.

  As the carbodiimide group-containing compound, for example, an isocyanate-terminated polycarbodiimide is synthesized by a condensation reaction involving decarbonization of a diisocyanate compound such as aromatic diisocyanate, aliphatic diisocyanate, and alicyclic diisocyanate, and then further reacted with an isocyanate group. And a compound to which a hydrophilic segment having a functional group having a property is added.

  As for the quantity of these crosslinking agents, 1-40 mass parts is preferable with respect to 100 mass parts of aqueous resin for forming the lowest layer membrane | film | coat. If the amount is less than 1 part by mass, the effect may not be obtained due to an insufficient amount. If the amount exceeds 40 parts by mass, the film becomes brittle due to excessive curing, and the corrosion resistance and work adhesion deteriorate.

  In the present invention, the resin (A2) contained in the lowermost layer film is, for example, an aqueous paint mainly composed of the aqueous resin (a1) for forming the resin (A1) and the silane coupling agent (s). Is applied to a metal plate used in the present invention and dried. In general, silane coupling agents can be chemically bonded to metal surfaces with functional groups such as hydroxyl groups and many functional organic resins, so in the presence of metal surfaces, functional organic resins, and silane coupling agents, And a functional organic resin can be crosslinked with a silane coupling agent. In the present invention, the aqueous resin (a1) and the silane coupling agent (s) as a main component are coated on a metal plate as the lowermost layer of the multilayer film and dried, whereby the functionality of the aqueous resin is determined. At least a part of the groups and at least a part of the functional groups on the metal surface each react with the silane coupling agent (s) to produce a resin (A2). At least a part of —O— (ether bond) or —OH (hydroxyl group) of the resin (A2) represented by the general formula (I) is bonded to the metal surface. The bond between the ether bond and the metal surface is a covalent bond, and the bond between the hydroxyl group and the metal surface is a hydrogen bond or a coordinate bond. Such chemical bonding between the lowermost layer and the metal surface increases the processing adhesion between them, and consequently improves the corrosion resistance of the processed part.

  When wet-on-wet coating method or multilayer simultaneous coating method is used to form the multilayer coating of the present invention, the laminated state from the lowermost layer to the outermost layer is once formed on a metal plate in a wet (wet) state. Heat to dry. In the water-containing state, since the mobility of the silane coupling agent (s) contained in the lowermost layer is high, at least a part of the silane coupling agent (s) is contained not only in the metal surface but also in the upper layer. Reacts efficiently with functional compounds. Due to the chemical bond between the lowermost layer and the layer one layer above, the work adhesion of both layers is increased, and consequently the corrosion resistance of the processed part is improved. Here, as described above, the wet-on-wet coating method is a method including a solvent-containing (wet) state after applying a coating liquid on a metal plate and before the solvent of the coating liquid is dried. In this method, another coating liquid is applied on top, and the solvent of the laminated coating liquid is simultaneously dried and cured to form a film. In addition, the multi-layer simultaneous coating method is a method of forming a film by simultaneously applying a plurality of layers of coating liquid to a metal surface in a laminated state using a slide curtain coater or slot die coater, and simultaneously drying and curing the solvent of the multilayer coating liquid. It is.

In the present invention, the silane coupling agent (s) used for forming the resin (A2) is selected from silane coupling agents having a molecular structure represented by the general formula YZ-SiX _m R _3-m. 1 type or 2 types or more. Among the functional groups in the molecular structure, -X group, which is a reaction point with the metal surface or other silane coupling agent, is a hydrolyzable alkoxy group having 1 to 3 carbon atoms or hydrolyzable. It is a halogeno group (fluoro group (—F), chloro group (—Cl), bromo group (—Br), etc.), or hydrolyzable acetoxy group (—O—CO—CH ₃ ). Among these, a hydrolyzable alkoxy group having 1 to 3 carbon atoms is preferable because it easily adjusts the hydrolyzability by changing the number of carbon atoms of the alkoxy group, and is preferably a methoxy group (—OCH ₃ ) or an ethoxy group (— OCH ₂ CH ₃ ) is particularly preferred. A silane coupling agent in which the —X group is a functional group other than the above is not desirable in the present invention because the hydrolyzability of the —X group is low or the hydrolyzability is too high.

  The -R group in the molecular structure is an alkyl group having 1 to 3 carbon atoms. When -R group is methyl group or ethyl group, compared to bulky n-propyl group or isopropyl group, -X group is relatively easy without disturbing water molecule access to the -X group in water-based paint. In order to hydrolyze, a methyl group is particularly preferable. Silane coupling agents in which the -R group is a functional group other than those described above are not desirable in the present invention because the hydrolyzability of the -X group is extremely low or the reactivity is too high.

  In the molecular structure, m indicating the number of substituents is an integer of 1 to 3. The more hydrolyzable -X groups, the more reactive points with the metal surface, and therefore m representing the number of substituents is preferably 2 or 3.

  -Z- in the molecular structure of the silane coupling agent (s) is a hydrocarbon chain having 1 to 9 carbon atoms, 0 to 2 nitrogen atoms, and 0 to 2 oxygen atoms. Of these, hydrocarbon chains having 2 to 5 carbon atoms, 0 or 1 nitrogen atoms, and 0 or 1 oxygen atoms are preferable because the water dispersibility and reactivity of the silane coupling agent are well balanced. When the number of carbon atoms in -Z- is 10 or more, the number of nitrogen atoms is 3 or more, or the number of oxygen atoms is 3 or more, the balance between water dispersibility and reactivity of the silane coupling agent is poor, which is desirable in the present invention. Absent.

In the molecular structure of the silane coupling agent (s), the —Y group that becomes a reaction point with the functional group of the aqueous resin (a1), the resin (A1) or other coexisting resin is the aqueous resin (a1), resin There is no particular limitation as long as it reacts with (A1) and other coexisting resins, but an epoxy group, amino group, mercapto group, or methylidene group (H ₂ C =) is preferred because of its high reactivity. A group or an amino group is particularly preferred.

(式中、Ａ１は水性樹脂（ａ１）を金属表面に塗布、加熱乾燥することにより得られる樹脂、また、Ｚ−は炭素原子数１〜９、窒素原子数０〜２、酸素原子数０〜２の炭化水素鎖で、「Ａ１〜Ｚ」の表記は、Ａ１とＺが両者の官能基を介して共有結合していることを示す。また、−０−はエーテル結合であり、−０Ｈ基は水酸基であり、−Ｘ基は炭素原子数１〜３の加水分解性アルコキシ基、加水分解性ハロゲノ基又は加水分解性アセトキシ基であり、−Ｒ基は炭素原子数１〜３のアルキル基であり、置換基の数を示すa、ｂ、ｃ、dはいずれも0〜3の整数で、かつa＋ｂ＋ｃ＋ｄ＝3である。) At the lowermost layer formed of the multilayer film coated metal sheet of the present invention, and such a molecular structure _{Y-Z-SiX m R 3} -m silane coupling agent represented by (s) -SiX _m group is the metal surface of the molecule, Further, when the -Y group reacts with the aqueous resin (a1), the resin (A1) or the like, the resin (A2) represented by the general formula (I) is obtained. That is, at least a part of —Si—X at the molecular terminal of the silane coupling agent (s) is hydrolyzed to produce one Si—OH (silanol group), and at least a part of the silane coupling agent (s) is a metal surface or another silane cup. Ring agent (s) is dehydrated and condensed with the hydroxyl group of the molecule and covalently bonded via an ether bond: Si-O-Me (Me is a metal atom) or -Si-O-Si *-(Si * is another silane coupling (Si atoms derived from agent molecules). On the other hand, the -Y group at the other end of the silane coupling agent (s) molecule reacts with a functional group of the aqueous resin (a1) or the resin (A1) to generate bonds of A1 to Z. The resin (A2) has a structure represented by the general formula (I). After these reactions are completed and the resin (A2) is formed, the number of —O—, —OH, —X, and —R groups bonded to the Si atom in (A2) is a, b, c, and d, respectively. A + b + c = m, and the —R group of the silane coupling agent (s) does not participate in the reaction and remains in the resin (A2). = 3. In addition, the notation of “A1 to Z” in the general formula (I) indicates that A1 and Z are covalently bonded via both functional groups.

(In the formula, A1 is a resin obtained by applying an aqueous resin (a1) to a metal surface and heating and drying, and Z- has 1 to 9 carbon atoms, 0 to 2 nitrogen atoms, and 0 to oxygen atoms. In the hydrocarbon chain of 2, the notation of “A1 to Z” indicates that A1 and Z are covalently bonded through the functional groups of both, −0− is an ether bond, and −0H group Is a hydroxyl group, -X group is a hydrolyzable alkoxy group having 1 to 3 carbon atoms, hydrolyzable halogeno group or hydrolyzable acetoxy group, and -R group is an alkyl group having 1 to 3 carbon atoms. And a, b, c, and d indicating the number of substituents are all integers of 0 to 3, and a + b + c + d = 3.)

Specific examples of the silane coupling agent (s), the general formula _{Y-Z-SiX m R 3} -m (-X group is a hydrolyzable alkoxy group having 1 to 3 carbon atoms, hydrolyzable halogeno group , Or a hydrolyzable acetoxy group, -R group is an alkyl group having 1 to 3 carbon atoms, m indicating the number of substituents is an integer of 1 to 3, -Z- is 1 to 9 carbon atoms, and the number of nitrogen atoms 0-2, hydrocarbon chain having 0-2 oxygen atoms, -Y group has a molecular structure of aqueous resin (a1) or resin (A1)), for example, vinyltrimethoxysilane, Vinyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxy Propyltriethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropyltri Methoxysilane, N-2- (aminoethyl) -3-aminopropyltriethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxy Examples thereof include silane, N-phenyl-3-aminopropyltrimethoxysilane, and 3-mercaptopropyltrimethoxysilane.

  In the present invention, when the lowermost layer film mainly composed of the resin (A1) and the resin (A2) is formed on the metal surface, the water-based paint used is a silane coupling agent with respect to 100 parts by mass of the water-based resin (a1). It is preferable to contain 1 to 100 parts by mass of (s). If the amount is less than 1 part by mass, the amount of the silane coupling agent (s) is small, and the crosslinked structure by the silane coupling agent does not develop so much, so that a sufficiently fine film cannot be obtained and the corrosion resistance may be insufficient. There is a possibility that the processing adhesion with a metal surface or the like is insufficient. On the other hand, when the amount exceeds 100 parts by mass, the effect of improving the adhesion is saturated, and an expensive silane coupling agent is used more than necessary, which may be uneconomical and may decrease the stability of the paint.

  The lowermost layer film in the present invention must contain one or more of the resin (A1) and the resin (A2) in a total amount of 50 to 100% by mass of the film, preferably the resin (A1 ) And resin (A2) in a total amount of 75 to 100% by mass of the film. When the total of the resin (A1) and the resin (A2) is less than 50% by mass of the lowermost layer film, the film has insufficient fineness and adhesion to the metal surface, and desired corrosion resistance and work adhesion cannot be obtained. .

In the present invention, the lowermost layer film containing the resin (A1) and the resin (A2) as main components is -C in the resin (A2) with respect to a total of 100 parts by mass of the resin (A1) and (A2). It is preferable that 0.1-30 mass parts of Si atoms which form -Si-O- bond are included. If the amount is less than 0.1 parts by mass, the amount of —C—Si—O— bond that affects the fineness of the film and the processing adhesion to the metal surface is small, and sufficient corrosion resistance and processing adhesion may not be obtained. There is sex. On the other hand, if it exceeds 30 parts by mass, the effect of improving adhesion to the metal surface and the like is saturated, and an expensive silane coupling agent is used more than necessary for film formation. May be reduced. The identification and quantification of Si atoms forming the one C—Si—O— bond can be performed by using an analysis method such as FT-IR spectrum of a film on a metal plate or ²⁹ Si-NMR. .

In the present invention, the adhesion amount after drying of the lowermost layer film having one or more of the resin (A1) and the resin (A2) as a main component is 0.01 to 3 g / m ^2. 0.05 to ² g / m ² is particularly preferable. Is less than 0.01 g / m ^2, film is too thin, the desired corrosion resistance, processability adhesion may not be obtained. On the other hand, if it exceeds 3 g / m ² , the coating film is too thick and the coating cost increases, and the work adhesion decreases, so that the corrosion resistance of the processed part may also decrease.

  The lowermost layer film of the multilayer film used in the present invention preferably further contains a polyphenol compound (D). A polyphenol compound is a compound having two or more phenolic hydroxyl groups bonded to a benzene ring or a condensate thereof, which can coordinately bond to a metal surface by a chelating action and hydrogen bond with a hydrophilic group of a coexisting aqueous resin. be able to. By blending such a polyphenol compound, the processing adhesion between the metal surface and the lowermost layer film and the processing adhesion between the lowermost layer film and the uppermost film are dramatically improved, and as a result, the corrosion resistance of the processed part is increased. Also improve.

  The polyphenol compound (D) used in the present invention is not particularly limited as long as it can be uniformly dissolved or finely dispersed in the aqueous paint used for forming the lowermost layer film. Even if it is not water-soluble or water-dispersible, it can be used as long as it penetrates between the hydrophobic chains of the water-based resin (a1) coexisting in the water-based paint and can be uniformly finely dispersed.

  Examples of the compound having two or more phenolic hydroxyl groups bonded to the benzene ring include gallic acid, pyrogallol, catechol and the like. The condensate of the compound having two or more phenolic hydroxyl groups bonded to the benzene ring is not particularly limited, and examples thereof include a polyphenol compound widely distributed in the plant kingdom, usually called tannic acid. Tannic acid is a general term for aromatic compounds having a complex structure having a large number of phenolic hydroxyl groups widely distributed in the plant kingdom. The tannic acid may be hydrolyzable tannic acid or condensed tannic acid. The tannic acid is not particularly limited. it can. The said polyphenol compound may be used by 1 type, and may use 2 or more types together.

  It is preferable to contain 1-100 mass parts of polyphenol compounds (D) with respect to a total of 100 mass parts of resin (A1) and resin (A2). If the amount is less than 1 part by mass, the amount of the polyphenol compound (D) is insufficient, so that sufficient process adhesion may not be obtained, and as a result, the processed part corrosion resistance may be insufficient. When the amount exceeds 100 parts by mass, the amount of the polyphenol compound (D) in the film is too large, and the work adhesion and corrosion resistance may be lowered, or the stability of the paint may be lowered.

  The lowermost film preferably further contains one or more (E) selected from the group consisting of phosphoric acid and hexafluorometal acid. The phosphoric acid and hexafluorometal acid may be used alone or in combination. These acids activate the metal surface by etching and promote the action of the silane coupling agent (s) and the polyphenol compound (D) on the metal surface. In addition to the above-described effects, phosphoric acid has the effect of forming a phosphate layer on the metal surface to passivate it, thereby improving the corrosion resistance. In addition to the above-described effects, hexafluorometal acid can form a stable thin film containing a metal oxide supplied from hexafluorometal acid on the metal surface forming the lowermost layer film. Improve. The phosphoric acid that can be used in the present invention is not particularly limited, and examples thereof include orthophosphoric acid, polyphosphoric acid (a linear polymer having a degree of polymerization of orthophosphoric acid up to 6 or a combination of two or more of these. Mixture) and metaphosphoric acid (single cyclic polymer having a degree of polymerization of orthophosphoric acid of 3 to 6 or a mixture of two or more of these). The phosphoric acid may be used alone or in combination of two or more. Since polyphosphoric acid having a degree of polymerization of more than 2 can be easily obtained industrially as a mixture of polyphosphoric acids having several degrees of polymerization, such a mixture is preferably used in the present invention.

  The hexafluorometal acid that can be used in the present invention is not particularly limited. For example, hexafluorophosphoric acid, hexafluorotitanic acid, hexafluorozirconic acid, hexafluorosilicic acid, hexafluoroniobic acid, hexafluoroantimonic acid And ammonium salts, potassium salts, sodium salts, calcium salts, magnesium salts and the like thereof. As described above, hexafluorometal acid forms a stable thin film containing a metal oxide on the metal surface that forms the lowermost layer film. In order to bring about such an effect, metals such as Ti, Si, Zr, Those containing one or more elements selected from the group consisting of Nb are preferred. The hexafluorometal acid may be used alone or in combination of two or more.

  1 type or 2 types or more (E) selected from the group which consists of phosphoric acid and hexafluoro metal acid contain 0.1-100 mass parts with respect to a total of 100 mass parts of resin (A1) and resin (A2). It is preferable to do. If the amount is less than 0.1 parts by mass, the action of these acids is insufficient, and thus the corrosion resistance may be lowered. When the amount exceeds 100 parts by mass, the coating becomes brittle, and the heat adhesion may decrease due to cohesive failure of the coating.

  It is preferable that the lowermost layer film further contains a phosphate compound (F). By blending this phosphate compound, a hardly soluble phosphate thin film can be formed on the metal surface when the lowermost layer film is formed. That is, when the metal is dissolved by the phosphate ions of the phosphate, the pH rises on the metal surface, and as a result, a precipitated thin film of phosphate is formed and the corrosion resistance is improved.

  The phosphate compound (F) that can be used in the present invention is not particularly limited, and examples thereof include orthophosphoric acid, polyphosphoric acid (a linear polymer having a degree of polymerization of orthophosphoric acid of up to 6, or Metal salts such as metaphosphoric acid (monocyclic cyclic polymers having a degree of polymerization of 3 to 6 or a mixture of two or more of these), phytic acid, phosphonic acid (a mixture of two or more of these) And organometallic salts such as phosphorous acid and phosphinic acid (hypophosphorous acid). The cation species is not particularly limited, and examples thereof include Cu, Co, Fe, Mn, Sn, V, Mg, Ba, Al, Ca, Sr, Nb, Y, Ni, and Zn, but Mg, Mn, Al, Ca and Ni are preferably used. The said phosphate compound may be used by 1 type, and may use 2 or more types together.

  It is preferable to contain 0.1-100 mass parts of phosphate compounds (F) with respect to a total of 100 mass parts of resin (A1) and resin (A2). If the amount is less than 0.1 parts by mass, the corrosion resistance may deteriorate because the action of the phosphate compound is insufficient. When the amount exceeds 100 parts by mass, the lowermost layer film becomes brittle, and the work adhesion may decrease due to film cohesive failure.

  The lowermost film preferably further contains metal oxide fine particles (G) made of at least one metal element selected from the group consisting of Si, Ti, Al, and Zr. By adding the metal oxide fine particles, the corrosion resistance can be further improved.

  Examples of the metal oxide fine particles (G) that can be used in the present invention include silica fine particles, alumina fine particles, titania fine particles, and zirconia fine particles, and those having an average particle diameter of about 1 to 300 nm are preferable. It is. These may be used alone or in combination of two or more. Among these, silica fine particles are added when both improvement of corrosion resistance and toughening of the coating are required. The silica fine particles are not particularly limited, and since the film is a thin film, colloidal silica having a primary particle diameter of 3 to 50 nm, silica fine particles such as fumed silica force are preferable.

  It is preferable that 1-100 mass parts of said metal oxide microparticles | fine-particles (G) are contained with respect to a total of 100 mass parts of resin (A1) and resin (A2). If the amount is less than 1 part by mass, the amount of the metal oxide fine particles is insufficient, so that the effect of improving the corrosion resistance may not be obtained. When the amount exceeds 100 parts by mass, the lowermost layer film becomes brittle, and the work adhesion may decrease due to film cohesive failure.

<Outermost layer film>
The outermost layer film of the present invention is a highly rigid resin obtained by applying a water-based resin paint (j) to the surface of the coating film, drying, and then curing by ultraviolet irradiation, electron beam irradiation, high temperature heating at 200 ° C. or higher, etc. (J) is contained in an amount of 50 to 95% by mass of the coating, and silica fine particles (C1) are contained in an amount of 5 to 35% by mass of the coating. The highly rigid resin (J) contained in the outermost layer film is a highly crosslinked resin that has been hardened by irradiating ultraviolet rays to an ultraviolet curable resin, and is highly crosslinked by irradiating an electron beam to an electron beam curable resin. A hardened resin, a heat-deposited resin heated to a temperature of 200 ° C. or higher and highly crosslinked or hardened, or a resin highly crosslinked or hardened by a crosslinking method other than the above. The resin has a high hardness with no scratches on the resin surface or only slight shallow scratches by either a dry steel wool sliding test or a wet cleanser sliding test shown below.

Steel wool sliding test in dry type: Cut out # 0000 steel wool into 50 mm square and affix it to a rubber plug (20 mm diameter) attached to the head of a rubbing tester (DIC type rubbing tester type 1 manufactured by Riken Engineering Co., Ltd.) Surface that was pressed against the resin surface with a load of 1.56 N / cm ² , subjected to a dry sliding test with a sliding distance of 60 mm, 60 reciprocations / min, 100 reciprocations, and then the resin surface was dyed and slid Visually observe the scratches.

Wet cleanser sliding test: Felt (One Touch Felt RN-01 handled by Yuzawaya Corp.) was cut into a 40 mm square and attached to the head of a rubbing tester (DIC type rubbing tester-1 type manufactured by Riken Engineering Co., Ltd.). Affixed to a rubber stopper (20 mm diameter) and fixed with rubber bands, soak the distilled water sufficiently in the felt part and gently wipe off the dripping water. Next, 0.5 cc of a silica mineral abrasive 5% liquid (a Kao Co., Ltd. homing cleanser diluted 10-fold with distilled water) was dropped on the resin surface at a load of 1.56 N / cm ² . The test piece is pressed against the test piece, and wet-type sliding test is performed at a sliding distance of 60 mm, 60 reciprocations / minute, and 100 reciprocations. After the resin surface is washed, the scratches on the dyed and slid surface are visually observed.

  In the present invention, the aqueous resin paint (j) is an aqueous ultraviolet curable resin paint or an electron beam curable resin paint, and the corresponding highly rigid resin (J) is an ultraviolet curable resin or an electron beam, respectively. A cured resin is preferred. In any case, the crosslinking time is as short as 1 second or less, and continuous in-line coating can be performed.

(式中、Ｒａｄは光開裂型重合開始剤の紫外線受光開裂で生成するラジカル(Ｒａｄ・)の付加物であり、−Ｘ^１基は水素原子又はメチル基であり、−Ｙ¹基は炭化水素基であり、−Ｚ¹基は、アニオン型、カチオン型またはノニオン型の親水基または該親水基を持つ炭化水素基である。) In the case of forming a film by an ultraviolet curing method, the aqueous resin coating (j) is an aqueous ultraviolet curing resin coating (b), and the highly rigid resin (J) is an ultraviolet cured resin (B1) represented by the following general formula (II). It is. In this case, the outermost layer film contains the UV-cured resin (B1) in an amount of 50 to 95% by mass and the silica fine particles (Cl) in an amount of 5 to 35% by mass. Among the constituent components of the outermost layer, components other than the UV-cured resin (B1) and silica fine particles (Cl) are unreacted aqueous polymerizable compounds that are starting compounds when the resin (B1) is produced by UV irradiation. Hydrocarbon (b1), unreacted photocleavable polymerization initiator (P), and the like.

(In the formula, Rad is an adduct of a radical (Rad.) Generated by UV photocleavage of a photocleavable polymerization initiator, -X ¹ group is a hydrogen atom or a methyl group, and -Y ¹ group is a hydrocarbon. And the —Z ¹ group is an anionic, cationic or nonionic hydrophilic group or a hydrocarbon group having the hydrophilic group.)

  The UV-cured resin (B1) is prepared by applying an aqueous paint (b) containing the aqueous polymerizable hydrocarbon (b1) and the photocleavable polymerization initiator (P) to the surface of the metal plate, drying it, and then irradiating with ultraviolet rays. It is resin obtained. The water-based paint (b) used in the present invention comprises 50 to 95% by mass of the nonvolatile content of the water-polymerizable hydrocarbon (b1) and the photocleavable polymerization initiator (P), and silica fine particles (Cl) as the nonvolatile content. In addition to the above, it contains 5 to 35% by mass. In addition, the hard ceramic fine particles, solid lubricant, crosslinking agent, polyphenol compound (D), phosphoric acid and hexafluorometal acid (E), phosphate compound (F), which will be described in detail later Etc. may be included.

  When the silica fine particles (Cl) are less than 5% by mass of the non-volatile content of the water-based paint (b), after the film formation, all of the scratch resistance, abrasion resistance, and corrosion resistance of the outermost layer film are insufficient. When the silica fine particles (Cl) exceed 35% by mass of the non-volatile content, the amount of fine particles in the outermost layer film after film formation is too large compared to the resin (B1), and the film has tightness, toughness and strength. The corrosion resistance and work adhesion become insufficient.

  Hard ceramic fine particles are often expensive, have a higher specific gravity than silica fine particles, and are difficult to uniformly disperse in water-based paints to form a film. Furthermore, silica fine particles have the effect of improving the corrosion resistance of the film after film formation. Is not high, the addition to the top film should be minimized.

  Moreover, it is preferable to contain 1-40 mass parts of solid lubricant with respect to 100 mass parts of non volatile matters of water-based paint (b). When the amount is less than 1 part by mass, the effect of improving the workability of the film after film formation is small. On the other hand, when the amount exceeds 40 parts by mass, the amount of lubricant in the film is too large and the fineness and adhesion of the film are impaired. Corrosion resistance, processing adhesion, etc. may be reduced.

  The addition of the crosslinking agent is limited to a range that retains the scratch resistance, abrasion resistance, and other necessary functions required for the outermost layer film.

  There are a radical polymerization type and a cationic polymerization type in the ultraviolet polymerization mechanism that has been industrialized. In the present invention, the aqueous polymerizable hydrocarbon (b1) in the unreacted film obtained by drying the water of the aqueous coating is polymerized. Therefore, even if a little moisture remains, a polymerized film is formed by a radical polymerization type in which the reaction proceeds rapidly. The cationic polymerization type is not only not inhibited by residual moisture or a coexisting basic compound, but also has a slower polymerization rate than the radical polymerization type, so that the industrial practicality is inferior to the radical polymerization type, which is not desirable in the present invention. In addition, the main initiation mechanism of photoradical polymerization includes a photocleavable type in which an initiator molecule undergoes intramolecular cleavage upon receiving ultraviolet light, and a radical can be generated by the initiator molecule alone, and an initiator molecule and a hydrogen donor compound. There is a hydrogen abstraction type that generates radicals by molecular reaction. In the present invention, a photocleavage type that does not require a hydrogen donor compound is used. In the hydrogen abstraction type, it is necessary to coexist with a hydrogen donor compound, and the formulation of the water-based paint becomes complicated, which is not desirable in the present invention.

(式中、−Ｘ¹基は水素原子又はメチル基、−Ｚ¹基は、アニオン型、カチオン型またはノニオン型の親水基または該親水基を持つ炭化水素基である。) In the present invention, the ultraviolet-cured resin (B1) represented by the general formula (II) has a carbon-carbon double bond group consisting of a methylidene group (H ₂ C =) at the end, and has the structure of the following general formula (IV) Drying the water of the water-based paint (b) mainly composed of the water-polymerizable hydrocarbon (b1) having a photocleavage and the photocleavable polymerization initiator (P), and then subjecting the film to radical polymerization by irradiation with ultraviolet rays Is obtained.

(In the formula, -X ¹ group is a hydrogen atom or a methyl group, and -Z ¹ group is an anionic, cationic or nonionic hydrophilic group or a hydrocarbon group having the hydrophilic group.)

In the above (IV), the carbon-carbon double bond group consisting of the methylidene group (H ₂ C =) at the molecular end is attacked by radicals generated by ultraviolet irradiation and becomes the starting point of polymerization. Examples of the mechanism by which the resin (B1) is produced from the photocleavable polymerization initiator (P) and the aqueous polymerizable hydrocarbon (b1) by ultraviolet irradiation are shown in the following reaction formulas 1 to 4.

Upon irradiation with ultraviolet light, the photocleavable polymerization initiator (P) is cleaved to generate radicals Rad ¹ · and Rad ² · (reaction formula 1, photocleavage). Radical Rad ¹ · acting on the aqueous polymerizable hydrocarbon (b1), so may be either Rad ² ·, generically represented as Rad · them. Rad · acts on the double bond group consisting of the methylidene group (H ₂ C =) at the terminal (b1) to generate a new radical with Rad · added to (b1) (Scheme 2, chain initiation) . This radical is added to the other (b1), and a radical having a larger molecular weight is generated (Reaction Formula 3, chain growth). This process is repeated one after another, and the radicals of the reaction intermediate are polymerized, and a resin (A1) is produced through a termination reaction due to the bonding between the radicals (Reaction Formula 4, Polymerization).

  Reaction Formula 1 illustrates the case where one type of photocleavable polymerization initiator (P) is used, but one type of initiator is used when forming the outermost layer film composed of the UV-cured resin (B1). (P) may be used alone or a mixture of two or more initiators (P) having different molecular structures may be used. Since photoinitiators exhibit different absorptions with respect to ultraviolet rays, the width of the photosensitive response (ultraviolet absorption wavelength range) can be expanded by using a mixture of two or more initiators. Therefore, in the present invention, two or more kinds of photocleavable polymerization initiators (P) are used in combination in order to control the degree of crosslinking, molecular weight, performance, etc., when forming the outermost layer film made of the ultraviolet curable resin (B1). There are things to do.

前記の水性重合性炭化水素（ｂ１）は、前記一般式（IV）に示したように、メチリデン基(Ｈ₂Ｃ＝)を有する炭素-炭素二重結合基を少なくとも1つ待つ必要がある。このような末端二重結合基は、一般式（IV）に示した二重結合基のほかに、更に、前記（IV）の−Ｚ¹基の末端にあっても、−Ｚ¹基の鎖の末端でない中途部位にぶら下がっていてもよい。いずれの場合でも、開始ラジカル（Ｒａｄ・)や反応中間体ラジカルが二重結合基に付加するためには、その二重結合基が、メチリデン基(Ｈ₂Ｃ＝)を有する炭素-炭素二重結合基でなければならない。この理由について、以下に述べる。 Reaction formulas 2 to 4 exemplify the case where one type of aqueous polymerizable hydrocarbon (b1) is used. However, when forming the outermost layer film composed of the ultraviolet-cured resin (B1), one type of ( b1) may be used alone, or a mixture of two or more types of (b1) in which at least one of the —X ¹ group or the —Z ¹ group is different may be used. However, in the case of a mixture, the hydrophilic group in the -Z ¹ group may become unstable when an anionic type and a cationic type are mixed, so these should not be used in combination. Acceptable combinations of hydrophilic groups are anionic and nonionic, or cationic and nonionic.

The aqueous polymerizable hydrocarbon (b1) needs to wait for at least one carbon-carbon double bond group having a methylidene group (H ₂ C═) as shown in the general formula (IV). Such a terminal double bond group includes, in addition to the double bond group shown in the general formula (IV), a chain of -Z ¹ group even at the terminal of the -Z ¹ group in the above (IV). You may hang in the middle part which is not the end of. In any case, in order for an initiating radical (Rad.) Or a reaction intermediate radical to be added to a double bond group, the double bond group is a carbon-carbon double having a methylidene group (H ₂ C =). Must be a linking group. The reason for this will be described below.

  When the hydrocarbon is a saturated hydrocarbon that does not have a carbon-carbon double bond group (> C = C <) itself, radical polymerization cannot be performed even if the radical coexists with the saturated hydrocarbon, and the polymerization is extremely high. It is difficult to. If a highly reactive radical such as a halogeno radical coexists with a saturated hydrocarbon, an alkyl radical can be generated by extracting a hydrogen atom from the saturated hydrocarbon. However, radical transfer reactions from these radicals to other surrounding saturated hydrocarbons (reactions in which saturated hydrocarbons attacked by radicals are excited and the attacked alkyl radicals are deactivated) Although there is a possibility of disappearing, radicals are successively added to saturated hydrocarbons and do not become polymerized. Therefore, in order for the hydrocarbon to be radically polymerizable, a carbon-carbon double bond group is required in the molecular chain.

In general, when the hydrocarbon has a carbon-carbon double bond group (> C = C <), the structural formula of such an unsaturated hydrocarbon is expressed as A ¹ A ² C = CB ¹ B ² . Here, the substituents A ¹ , A ² , B ¹ , B ² are hydrogen atoms or hydrocarbon groups, or hetero atoms other than hydrogen atoms and carbon atoms (for example, —F, —Cl, —Br, —I, etc.) Or a hetero substituent whose central atom is not a carbon atom (for example, —N (CH ₃ ) ₂ , —O—CH ₂ CH ₃ , —SO ₃ Na, etc.). In the unsaturated hydrocarbon A ¹ A ² C═CB ¹ B ² , it is attached to at least one of A ¹ or A ² attached to the left double bond carbon and to the right double bond carbon. When at least one of B ¹ or B ² is a hydrocarbon group having 1 or more carbon atoms, a hetero atom other than a hydrogen atom and a carbon atom, or a hetero substituent whose central atom is not a carbon atom , Since atoms or substituents higher than hydrogen atoms are bonded to both double bond carbons, the double bond sites are shielded very strongly, and the radicals are not close to the carbon-carbon double bond sites. Therefore, it is practically impossible to add a radical to the double bond site, and it cannot be used as the aqueous polymerizable hydrocarbon (b1) of the present invention. On the other hand, in the unsaturated hydrocarbon A ¹ A ² C═CB ¹ B ² , at least one of B ¹ or B ² ) attached to the double bond carbon atom on the right side is a substituent that is bulkier than the hydrogen atom. However, if both of the substituents A ¹ and A ² attached to the left double bond carbon are hydrogen atoms, the A ¹ A ² C═CB ¹ B ² is a methylidene group (H _{2 having} a small shielding power). C =) (H ₂ C═CB ¹ B ² ), so that either substituent A ¹ or A ² and substituent B ¹ or B ² are both bulkier than hydrogen atoms. Unlike some cases, radicals come closer to the carbon-carbon double bond site. Therefore, in order for the radical to undergo sequential addition polymerization to the carbon-carbon double bond site of the unsaturated hydrocarbon, the aqueous polymerizable hydrocarbon (b1) in the present invention is a carbon- having a methylidene group (H ₂ C =). The structure must be such as H ₂ C═CB ¹ B ² waiting for at least one carbon double bond group.

(式中、−Ｘ¹基は水素原子又はメチル基、−Ｚ¹基は、アニオン型、カチオン型またはノニオン型の親水基または該親水基を持つ炭化水素基である。) Furthermore, in order to stabilize the unsaturated hydrocarbon H ₂ C═CB ¹ B ² in a water-based paint and efficiently perform radical polymerization after wet coating and moisture drying, the substituent B ¹ is anionic, cationic or It is a nonionic hydrophilic group or a hydrocarbon group having the hydrophilic group, and the remaining substituent B ² must be a small hydrogen atom or a methyl group. If B ¹ is the aforementioned hydrophilic substituent, the unsaturated hydrocarbon H ₂ C═CB ¹ B ² is stably dissolved or finely dispersed in the water-based paint. However, since such hydrophilic substituents are very bulky, radicals are unlikely to approach the double bond site of unsaturated hydrocarbon H ₂ C═CB ¹ B ² , and the reaction rate is slow. Furthermore, if the remaining substituent B ² is a bulky alkyl group having 2 or more carbon atoms, a heteroatom other than a hydrogen atom and a carbon atom, or a hetero substituent whose central atom is not a carbon atom, the bulky substituent B ^{1 is used.} The radical shielding effect due to the coexistence of B ² and B ² is very large, and radical polymerization does not substantially occur. However, in unsaturated hydrocarbon H ₂ C═CB ¹ B ² , radical polymerization is carried out at a practical reaction rate if B ¹ is a bulky hydrophilic substituent and B ² is a small hydrogen atom or methyl group. Therefore, the aqueous polymerizable hydrocarbon (b1), which is a starting compound when the resin (B1) is produced by receiving ultraviolet light, must have a structure represented by the general formula (IV).

(In the formula, -X ¹ group is a hydrogen atom or a methyl group, and -Z ¹ group is an anionic, cationic or nonionic hydrophilic group or a hydrocarbon group having the hydrophilic group.)

The resin (B1) used in the present invention is produced by radical polymerization of the aqueous polymerizable hydrocarbon (b1) as shown in the reaction formulas 2 to 4. Therefore, the —X ¹ group and —Z ¹ group of the resin (B1) are the same as those of (IV). Also, -Y ¹ group in the resin (B1), as shown in Scheme 4, is an addition polymer of a number of aqueous polymeric hydrocarbon (b1), (b1) structural features of the molecule (e.g. The number of carbon-carbon double bond groups having a methylidene group (H ₂ C =) in one molecule, the type and number of other reactive groups in the molecule) and the water content during coating ( In the (wet) film, (b1) the structure of the —Y ¹ group to be produced varies depending on the type of polymerization initiator and cross-linking agent coexisting with the molecule, and a specific structural formula cannot be applied. Therefore, in the general formula (II) showing the structure of the resin (B1), the —Y ¹ group is simply referred to as “hydrocarbon group” as follows.

(式中、Ｒａｄは光開裂型重合開始剤の紫外線受光開裂で生成するラジカル(Ｒａｄ・)の付加物であり、−Ｘ¹基は水素原子又はメチル基であり、−Ｙ¹基は炭化水素基であり、−Ｚ¹基は、アニオン型、カチオン型またはノニオン型の親水基または該親水基を持つ炭化水素基である。） The ultraviolet curable resin (B1) used in the present invention has a structure represented by the following general formula (II).

(In the formula, Rad is an adduct of a radical (Rad.) Generated by UV photocleavage of a photocleavable polymerization initiator, -X ¹ group is a hydrogen atom or a methyl group, and -Y ¹ group is a hydrocarbon. The —Z ¹ group is an anionic, cationic or nonionic hydrophilic group or a hydrocarbon group having the hydrophilic group.)

(式中、Ｒａｄは光開裂型重合開始剤の紫外線受光開裂で生成するラジカル(Ｒａｄ・)の付加物であり、−Ｙ¹基は炭化水素基であり、−Ｚ¹基は、アニオン型、カチオン型またはノニオン型の親水基または該親水基を持つ炭化水素基である。)

(式中、−Ｚ¹基は、アニオン型、カチオン型またはノニオン型の親水基または該親水基を持つ炭化水素基である。) In the present invention, the —X ¹ group of the aqueous polymerizable hydrocarbon (b1), which is a starting compound when the resin (B1) is produced by UV light reception, is preferably a hydrogen atom rather than a methyl group. . That is, the resin (B1) is represented by the following general formula (III), and the aqueous polymerizable hydrocarbon (b1) is represented by the following general formula (V) in which the terminal double bond group is a vinyl group (H ₂ C═CH—). It is preferable to use an aqueous polymerizable hydrocarbon (b2) having the structure: This is because, firstly, the hydrogen atom is much smaller than the methyl group and has little radical shielding effect, so that the radical addition reaction to the aqueous polymerizable hydrocarbon (b2) occurs very quickly. Second, when the —X ¹ group of the aqueous polymerizable hydrocarbon (b1) is a hydrogen atom, an acrylate radical (for example, Rad—CH ₂ —CHZ ^1. ) Generated by radical addition is a secondary radical, and —X 1 ^{Since the} tertiary methacrylate radical (for example, Rad-CH ₂ -C (CH ₃ ) Z ¹ . It is because it adds to hydrocarbon (b2) rapidly.

(In the formula, Rad is an adduct of a radical (Rad.) Generated by ultraviolet light-receiving cleavage of a photocleavable polymerization initiator, -Y ¹ group is a hydrocarbon group, -Z ¹ group is an anionic type, (It is a cationic or nonionic hydrophilic group or a hydrocarbon group having the hydrophilic group.)

(Wherein the —Z ¹ group is an anionic, cationic or nonionic hydrophilic group or a hydrocarbon group having the hydrophilic group.)

In the present invention, the -Z ¹ group constituting a part of the ultraviolet-cured resin (B1) or the aqueous polymerizable hydrocarbon (b1) is, if (b1) is water-soluble or water-dispersible due to its hydrophilic effect, Any of a monomer, an oligomer, and a polymer having a higher molecular weight than those may be used. In the case of monomers and oligomers, the —Z ¹ group has a low molecular weight, but in the case of polymers, the —Z ¹ group is a high molecular weight long chain group, a two-dimensional crosslinking group, or a three-dimensional crosslinking group.

In the present invention, the -Z ¹ group is a hydrocarbon group having an anionic, cationic or nonionic hydrophilic group. The anionic or cationic hydrophilic group mentioned here is a group that can dissolve or disperse the aqueous polymerizable hydrocarbon (b1) in water by forming a water-soluble salt with an ion having an opposite charge, or a water solution thereof. There is no particular limitation as long as it is a group consisting of a functional salt. In the anion type, an acid group such as a carboxyl group (—COOH), a sulfate group (—SO ₃ H), a sulfate ester group (—OSO ₃ H), a phosphate group (—P═O (OH) ₂ ), and the like One COONa, —COOK, —COONH ₄ , —SO ₃ Na, —SO ₃ K—SO ₃ NH ₄ , —OSO ₃ Na, —P obtained by reacting a base such as NaOH, KOH, NH ₃ and various amines A neutralizing group such as ═O (ONa) ₂ is preferable, and the —Z ¹ group of the aqueous polymerizable hydrocarbon (b1) and the resin (B1) obtained therefrom is usually one having these acid groups. The thing with the sum is mixed. Further, the cationic, Cl ^- and Br ^- anions quaternary ammonium salt or pyridinium salt formed by neutralizing the like are preferable. In the nonionic type, a polyoxyethylene group (— (CH ₂ —CH ₂ —O) _x — group, the number of repeating units x is an integer of about 5 to 20) or a polyoxypropylene group (— (CH ₂ — CH (CH ₃ ) —O) _y — group, the number y of repeating units is generally an integer of 5 to 20).

As already described, when forming the outermost layer film made of the ultraviolet curable resin (B1) used in the present invention, even if one kind of aqueous polymerizable hydrocarbon (b1) is used alone, -X ¹ group or A mixture of two or more (b1) s in which at least one of the —Z ¹ groups is different may be used. However, in the case of a mixture, the hydrophilic group in the -Z ¹ group may become unstable when an anionic type and a cationic type are mixed, so these should not be used in combination. Acceptable combinations of hydrophilic groups are anionic and nonionic, or cationic and nonionic.

In the present invention, the —Z ¹ group constituting a part of the ultraviolet curable resin (B1) or the aqueous polymerizable hydrocarbon (b1) is an aqueous epoxy resin, aqueous polyester resin, aqueous polyurethane resin, aqueous (meta It is preferably one or more selected from the group consisting of acrylic resins, aqueous amino resins and aqueous silicone resins.

Examples of the aqueous epoxy resin include resins synthesized by the following procedure. First, a bisphenol type epoxy resin having both terminal epoxy groups is obtained by polycondensation of bisphenol A, bisphenol F or hydrogenated bisphenol A, or a mixture of two or more selected from bisphenol A, bisphenol F and hydrogenated bisphenol A with epichlorohydrin. Synthesize. Next, a carbon-carbon double bond-containing monocarboxylic acid (such as (meth) acrylic acid) with two hydrogen atoms attached to one double bond carbon and a high acid value with many carboxyl groups attached to the resin chain A resin is appropriately added, and these are added to the epoxy resin by a reaction between an epoxy group and a carboxyl group, respectively. This operation is an operation of imparting a carbon-carbon double bond group having a methylidene group (H ₂ C =) to the end of the epoxy resin chain and increasing the acid value of the epoxy resin with a high acid value resin. . Finally, the unreacted carboxyl group remaining in the added high acid value resin is neutralized with a base to make it aqueous. Since the high acid value resin has many carboxyl groups attached to one resin chain, one high acid value resin chain can be bonded to a plurality of epoxy resin chains. Thus, an aqueous epoxy resin having many carbon-carbon double bond groups having a methylidene group (H ₂ C =) at the end of the resin chain can also be obtained.

Among the above-mentioned bisphenol type aqueous epoxy resins having a carbon to carbon double bond group having a methylidene group (H ₂ C =) at the resin chain end, it is obtained using bisphenol A, acrylic acid and the high acid value resin. Bisphenol A water-based epoxy resin is excellent in industrial productivity, and the carbon-carbon double bond having a methylidene group (H ₂ C =) derived from acrylic acid is easily attacked by radicals, and is cured by ultraviolet rays. Since the reaction rate is fast, it is preferably used.

Examples of the aqueous polyester-based resin having at least one carbon-carbon double bond group having a methylidene group (H ₂ C═) at the terminal include resins synthesized by the following procedure. First, aliphatic dicarboxylic acids (for example, saturated aliphatic dicarboxylic acids such as malonic acid, succinic acid, and adipic acid, and unsaturated aliphatic dicarboxylic acids such as maleic acid, fumaric acid, itaconic acid, maleic anhydride, and fumaric anhydride. Acid), aromatic dicarboxylic acid (e.g., terephthalic acid, isophthalic acid, phthalic anhydride, etc.) and polyvalent carboxylic acid having 3 or more carboxyl groups in one molecule (e.g., trimellitic anhydride, Mixture with citric acid, the above-mentioned high acid value resin, etc.) and glycol (for example, ethylene glycol, propylene glycol, 1,3-butylene glycol, 1,6-hexanediol, diethylene glycol, triethylene glycol, neopentyl glycol) Dehydrated polycondensation with hydrogenated bisphenol A, etc.) and many unreacted carboxyl groups are attached to the resin chain After synthesizing a high acid value polyester resin, the hydroxyl group at the end of the polyester resin and a carbon-carbon double bond-containing monocarboxylic acid ((meth) acrylic) with two hydrogen atoms attached to one double bond carbon Acid) or a carboxyl group at the end of the polyester resin and glycidyl (meth) acrylate to react with carbon to carbon dioxygen having a methylidene group (H ₂ C =) at the end of the polyester resin chain. Adds a heavy bond group. Finally, the acidity of the unreacted carboxyl group remaining in the resin chain is neutralized to make it aqueous.

Examples of the aqueous polyurethane resin having at least one carbon-carbon double bond group having a methylidene group (H ₂ C═) at the terminal include resins synthesized by the following procedure. First, a polyurethane resin having an isocyanate group at the end is synthesized by a polyaddition reaction of a polyisocyanate having two or more isocyanate groups and a polyol having two or more hydroxyl groups, and then the isocyanate group of this resin and one molecule are synthesized. A number of carboxyl groups were attached to the resin chain by reacting the hydroxyl group of a hydroxy acid (for example, dimethylolpropionic acid, glyceric acid, tartaric acid, etc.) having two or more hydroxyl groups and one or more carboxyl groups therein. Synthesize high acid value urethane resin. This hydroxyl group at the end of the high acid value urethane resin is reacted with a carbon-carbon double bond-containing monocarboxylic acid (such as (meth) acrylic acid) in which two hydrogen atoms are attached to one double bond carbon, Alternatively, the carboxyl group at the end of the high acid value urethane resin is reacted with glycidyl (meth) acrylate to give a carbon-carbon double bond group having a methylidene group (H ₂ C =) at the end of the urethane resin chain. Finally, the acidity of the unreacted carboxyl group remaining in the resin chain is neutralized to make it aqueous.

  The polyisocyanates include aromatic, alicyclic and aliphatic polyisocyanates. Examples of aromatic polyisocyanates include tolylene diisocyanate (TDI) (2,4- or 2,6-TDI), diphenylmethane diisocyanate (MDI) (4,4′- or 2,4′-MDI), polymeric MDI. , Xylylene diisocyanate (XDI), naphthylene diisocyanate (NDI) (usually 1,5-NDI), paraphenylene diisocyanate (PPDI), tetramethylxylylene diisocyanate (TMXDI), tolidine diisocyanate (TODI), 3,3′- Examples of alicyclic polyisocyanates such as dimethoxy-4,4′-biphenylene diisocyanate include dicyclohexylmethane diisocyanate (HMDI) (4,4′- or 2,4′-HMDI), isophorone diisocyanate (IPDI), isopropyl Redenbis (4-cyclohexyl isocyanate) (IPC), hydrogenated xylylene diisocyanate (hydrogenated XDI), cyclohexylene diisocyanate (CHPI) (usually 1,4-CHPI), 1,5-tetrahydronaphthalene diisocyanate, etc. are also aliphatic. Examples of the polyisocyanate include hexamethylene diisocyanate (HDI), lysine diisocyanate (LDI), and tetramethylene diisocyanate.

  Examples of the polyol include (poly) alkylene glycol, polyester polyol, polyol having a C—C bond as a main chain, and other polyols.

  Here, as the (poly) alkylene glycol, for example, (poly) ethylene glycol (ethylene glycol, diethylene glycol, triethylene glycol, etc.), 1,2-propylene glycol, 1,3-propylene glycol, polyethylene / propylene glycol, neopentyl Examples include glycol, 1,2-butylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, 3-methyl-1,5-pentanediol, hexamethylene glycol, and the like.

  Examples of polyester polyols include low molecular weight polyols (for example, relatively low molecular weight (poly) alkylene glycols, bisphenol A, hydrogenated bisphenol A, trimethylolpropane, glycerin, etc.) and polyvalent carboxylic acids (for example, Succinic acid, glutaric acid, adipic acid, sebacic acid, phthalic acid, isophthalic acid, terephthalic acid, trimellitic anhydride, tetrahydrophthalic acid, endomethylenetetrahydrophthalic acid, hexahydrophthalic acid, etc.) Examples include polyester polyols having a hydroxyl group at the terminal.

  Examples of the polyol having a C—C bond as the main chain include methyl (meth) acrylate-vinyl alcohol copolymer, polyolefin having hydroxyl groups at both ends (polyethylene having a hydroxyl group at both ends, polypropylene, etc.), and ethylene-acetic acid. Examples thereof include a vinyl copolymer part or a completely hydrolyzed product.

  Examples of other polyols include bisphenol A, hydrogenated bisphenol A, trimethylolpropane, and glycerin.

Examples of the aqueous (meth) acrylic resin having at least one carbon-carbon double bond group having a methylidene group (H ₂ C═) at the terminal include resins synthesized by the following procedure. First, (meth) acrylic acid is polymerized to form an oligomer having a terminal carboxyl group, and (meth) acrylic acid ester (for example, ethyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-butyl ( (Meth) acrylate, 2-hydroxyethyl (meth) acrylate, glycidyl (meth) acrylate, etc.) and (meth) acrylic acid are copolymerized to synthesize a high acid value (meth) acrylic resin having a terminal carboxyl group. . Next, the terminal carboxyl group of this resin and glycidyl (meth) acrylate are reacted to give a carbon-carbon double bond group having a methylidene group (H ₂ C =) at the resin chain end. Finally, the acidity of the unreacted carboxyl group remaining in the resin chain is neutralized to make it aqueous. Further, for example, a resin synthesized by the following procedure can be given. A glycidyl (meth) acrylate is polymerized to produce an oligomer having a terminal glycidyl group, and a high acid value having a terminal glycidyl group is obtained by copolymerizing the oligomer with a mixture of the (meth) acrylic acid ester and (meth) acrylic acid. A (meth) acrylic resin is synthesized. Next, the terminal glycidyl group of this resin and (meth) acrylic acid are reacted to give a carbon-carbon double bond group having a methylidene group (H ₂ C =) at the resin chain end. Finally, the acidity of the unreacted carboxyl group remaining in the resin chain is neutralized to make it aqueous.

Examples of the aqueous amino resin having at least one carbon-carbon double bond group having a methylidene group (H ₂ C═) at the terminal include resins synthesized by the following procedure. First, a compound having two or more amino groups (for example, urea, melamine, benzoguanamine, etc.) and formaldehyde are condensed to synthesize an amino resin. As long as the water dispersibility of the resulting resin is not lost, at least part of the methylol group at the end of the amino resin is etherified with a lower alcohol (for example, methyl alcohol, ethyl alcohol, butyl alcohol, etc.) to form an alkoxymethyl group. To do. Next, a compound having a carbon-carbon double bond having a methylidene group (H ₂ C =) in one molecule and a hydroxyl group is reacted with a methylol group or an alkoxymethyl group of the resin via the hydroxyl group to obtain a methylidene group ( An aqueous amino resin having a carbon-carbon double bond group having H ₂ C =) is used.

Here, examples of the compound having a carbon-carbon double bond having a methylidene group (H ₂ C═) and a hydroxyl group in one molecule include 2-hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate. N-methylol (meth) acrylamide, 2-hydroxyethyl-o-xylylene (meth) acrylate, 2-hydroxypropyl-o-xylylene (meth) acrylate, and the like.

Examples of the aqueous silicone resin having at least one carbon-carbon double bond group having a methylidene group (H ₂ C =) at its terminal include reactive polysiloxanes having a silanol group or an alkylsilanol group, and the aqueous Examples thereof include resins obtained by reacting with epoxy groups, hydroxyl groups, amino groups, and the like of epoxy resins, aqueous polyester resins, aqueous polyurethane resins, aqueous (meth) acrylic resins, and aqueous amino resins.

  In general, when an ultraviolet curable resin coating mainly composed of radically polymerizable hydrocarbons does not contain a photopolymerization initiator, radicals effective for polymerization of polymerizable hydrocarbons will not be generated even when irradiated with ultraviolet rays after film formation. Such a paint always contains a photopolymerization initiator. In the present invention, the photo-cleavable polymerization initiator (P) is always blended in the water-based paint for forming the outermost layer film.

The photocleavable polymerization initiator (P) used in the present invention is not particularly limited, but has an absorption wavelength band in the ultraviolet light region of 200 to 400 nm, absorbs ultraviolet light of a specific wavelength, and cleaves within the molecule to generate radicals. The resulting compound is preferred. Among them, one or a mixture of two or more selected from the following formulas (P1) to (P10) is particularly preferable. This is because these are compatible with (b1) when formed into an aqueous paint together with the aqueous polymerizable hydrocarbon (b1), and can be uniformly dispersed in the aqueous paint together with (b1) and have the ability to generate radicals by receiving UV light. This is because the reactivity of the generated radical is high. The compound names of (P1) to (P10) are benzoin (P1), benzoin methyl ether (P2), benzoin ethyl ether (P3), benzoin isopropyl ether (P4), 1-hydroxycyclohexyl phenyl ketone (P5), 2,2-dimethyl-2-hydroxyacetophenone (P6), 2,2-diethoxyacetophenone (P7), 2,2-dimethoxy-2-phenylacetophenone (P8), 2-methyl-1- [4- (methylthio ) Phenyl] -2- (4-morpholinyl) -1-propanone (P9), bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide (P10).

  The photocleavable polymerization initiator (P) used in the present invention is blended in the aqueous paint in a range of 0.2 to 20 parts by mass with respect to 100 parts by mass of the nonvolatile content of the aqueous paint used for forming the outermost layer film. Of these, it is more preferable to blend in the range of 0.5 to 10 parts by mass. When the photocleavable polymerization initiator (P) contains only a trace amount of less than 0.2 parts by mass, a sufficient amount of initiator radicals are not generated by receiving ultraviolet light, and the water-polymerizable hydrocarbon (b1) Most of them remain in the film unreacted, so that the scratch resistance and wear resistance of the outermost layer film are likely to be insufficient. When the photocleavable polymerization initiator (P) exceeds 20 parts by mass, a very large number of initiator radicals (Rad.) Are generated all at once by UV light reception, and the consumption rate of the aqueous polymerizable hydrocarbon (b1) is very high. Therefore, there is a high possibility that the aqueous polymerizable hydrocarbon (b1) will be consumed before each chain-grown chain is sufficiently polymerized. Therefore, there is a high possibility that the scratch resistance and wear resistance of the outermost layer film will be insufficient.

In the present invention, Rad constituting a part of the ultraviolet-cured resin (B1) is a radical (Rad ·) generated by light-receiving cleavage of the photocleavable polymerization initiator (P). As shown in the figure, it is added to the aqueous polymerizable hydrocarbon (b1). In the present invention, the structure of Rad is not particularly limited, but one or more terminal groups having structures represented by the following formulas (Rad1) to (Rad13) are preferable. This is because the photocleavable polymerization initiator (P) particularly preferred in the present invention is one or more selected from the above formulas (P1) to (P10). This is because radicals (Rad1 ·) to (Rad13 ·) corresponding to the structures of () to (Rad13) are generated.

  In the present invention, the silica fine particles (C1) are added to further improve all of the scratch resistance, wear resistance, and corrosion resistance of the ultraviolet-cured resin (B1). There is no restriction | limiting in particular as a silica fine particle, Since a membrane | film | coat is a thin film, it is preferable that they are silica fine particles, such as colloidal silicic force with a primary particle diameter of 3-50 nm, and fumed silicic force.

  When the water-based resin paint (j) of the present invention is a water-based electron beam curable resin paint and the high-hardness resin (J) is an electron beam-cured resin, the outermost layer is coated with the electron beam. The resin contains 50 to 95% by mass of the film and 5 to 35% by mass of silica fine particles (Cl). Among the constituent components of the outermost layer, components other than the electron beam cured resin and silica fine particles (Cl) are unreacted resin, unreacted aqueous polymerizable hydrocarbon, and the like.

The electron beam curable resin contained in the water-based electron beam curable resin coating is the water resin (a1) used in the formation of the lowermost layer film of the multilayer film of the present invention, or more preferably by ultraviolet curing. It is 1 type, or 2 or more types chosen from the group which consists of the said water-polymerizable hydrocarbon (b1) used when forming a surface layer membrane | film | coat. Since the energy of the electron beam used for the crosslinking reaction of the resin is much higher than that of ultraviolet rays, when the aqueous resin (a1) or the aqueous polymerizable hydrocarbon (b1) is irradiated with an electron beam, the resin chain or hydrocarbon chain is bonded. Cuts everywhere, and a radical is generated at that site. There are several cases of polymerization reactions using such radicals. For example, if radicals generated anywhere in different resin chains or hydrocarbon chains are combined, a crosslinked polymer in which resin chains and hydrocarbon chains are bonded to each other. Produces. Since many radicals are simultaneously exerted on intermolecular bonds, the resulting polymer has a very high molecular weight compared to the original resin or hydrocarbon. Further, for example, terminal methylidene double bond group consisting of group (H ₂ C =) of the aqueous polymerizable hydrocarbon (b1) is, if in the vicinity of such radicals, similar to the reaction scheme 2-4 The polymer is radical polymerized by chain reaction and becomes high molecular weight. In this case, it becomes a graft polymerization chain starting from the radical generation site of the resin chain or hydrocarbon chain and growing to the side of the resin chain or hydrocarbon chain. In the case as described above, the reaction may be a single reaction or a complex reaction intricately entangled depending on the type and abundance of the aqueous resin (a1) and the aqueous polymerizable hydrocarbon (b1). At the end of the reaction, crosslinking of resin chains and hydrocarbon chains and a network structure are developed, resulting in an electron beam cured resin.

  The electron beam cured resin is applied to the surface of the metal plate with an aqueous electron beam curable resin coating containing the aqueous resin (a1) or the aqueous polymerizable hydrocarbon (b1). It is a resin obtained by beam irradiation. The aqueous electron beam curable resin coating used in the present invention comprises a total of the aqueous resin (a1) and the aqueous polymerizable hydrocarbon (b1) of 50 to 95% by mass of non-volatile content and silica fine particles (Cl) of non-volatile content. 5 to 35% by mass, in addition, hard ceramic fine particles, solid lubricant, cross-linking agent, polyphenol compound (D), phosphoric acid and hexafluorometal acid (E) mentioned in the description of the ultraviolet curable resin coating , And may contain a phosphate compound (F).

  Reasons for adding silica fine particles (Cl) to electron beam curable resin coatings, suitable particle diameters, reasons why the content of silica fine particles (Cl) in the coatings is preferably 5 to 35% by mass, hard ceramics The reasons why the addition of fine particles to the uppermost layer film should be minimized, the preferred range of the content of the solid lubricant, and the purpose of the addition of the crosslinking agent are all the contents mentioned in the description of the ultraviolet curable resin coating. The same.

(式中、−Ｘ¹基は水素原子又はメチル基、−Ｚ¹基は、アニオン型、カチオン型またはノニオン型の親水基または該親水基を持つ炭化水素基である。) In the present invention, the aqueous polymerizable hydrocarbon (b1) used when the outermost layer film is formed by electron beam curing is represented by the following general formula (IV) for the same reason as in the case of (b1) used during ultraviolet curing. ) Must be the structure shown.

(In the formula, -X ¹ group is a hydrogen atom or a methyl group, and -Z ¹ group is an anionic, cationic or nonionic hydrophilic group or a hydrocarbon group having the hydrophilic group.)

(式中、−Ｚ¹基は、アニオン型、カチオン型またはノニオン型の親水基または該親水基を持つ炭化水素基である。) Moreover, the said water-polymerizable hydrocarbon (b1) used when forming an outermost layer film | membrane by electron beam hardening is the following general formula (V) for the same reason as the case of (b1) used at the time of ultraviolet curing. The structure shown in FIG.

(Wherein the —Z ¹ group is an anionic, cationic or nonionic hydrophilic group or a hydrocarbon group having the hydrophilic group.)

  Regarding the aqueous polymerizable hydrocarbon (b1) used when the outermost layer film is formed by electron beam curing, structural features other than those described above are the same as in the case of (b1) used during ultraviolet curing.

  As described above, when the aqueous resin (a1) or the aqueous polymerizable hydrocarbon (b1) is irradiated with an electron beam, the bond between the resin chain and the hydrocarbon chain is broken everywhere to generate radicals. In this case, a polymerization initiator necessary as a radical generating source is unnecessary in the case of electron beam curing.

  In the present invention, as already described, since the crosslinking time of the resin is short and in-line coating is easy, the aqueous resin coating (j) is an aqueous ultraviolet curable resin coating or an electron beam curable resin coating. However, it is also possible to use an aqueous heating film-forming resin paint as the aqueous resin paint (j). In this case, the corresponding highly rigid resin (J) is a resin that has been highly crosslinked and hardened by heating the heat-deposited resin at a temperature of 200 ° C. or higher for several tens of seconds to several tens of minutes. The outermost layer film contains 50 to 95% by mass of this resin and 5 to 35% by mass of silica fine particles (Cl). Among the film constituent components of the outermost layer, the components other than the above-mentioned heat-deposited resin and silica fine particles (Cl) are unreacted heat-deposited resin.

  The aqueous heating film-forming resin coating used here is one or more selected from the aqueous heating film-forming resin coatings (a) used in forming the lowermost film of the multilayer coating of the present invention. And the heat-deposition type resin contained in the paint is one or more selected from the aqueous resin (a1) used in forming the lowermost layer film of the multilayer film of the present invention. However, because the required performance of the lowermost layer and the outermost layer is different (the performance required for the lowermost layer is corrosion resistance and work adhesion, and the outermost layer is scratch resistance and wear resistance), both have the same composition and the same structure. A heat-deposition type resin is never used.

  Depending on the type and structure of the resin, the type and content of the functional group, the presence and type of the reaction catalyst, etc. It is desirable to hold for 10 seconds to several tens of minutes and heat. However, under such severe heating conditions, not only the outermost layer film but also at least a part of the aqueous resin (a1) used for forming the lowermost layer film is excessively crosslinked or cannot withstand high heat. In this case, thermal decomposition, resin chain scission, thermal oxidation, reduction in denseness, plastic flow deformation and the like occur. Therefore, there is a risk that performance such as corrosion resistance and work adhesion of the lowermost layer film may be deteriorated. When an aqueous heating film forming resin is used for forming the outermost layer of the multilayer film of the present invention, it is used for forming the lowermost layer. Special attention needs to be paid to the selection of the heat-deposition type resin.

  Even when the outermost layer film is formed by any method such as ultraviolet irradiation, electron beam irradiation, or high temperature heating at 200 ° C. or more, if the silica fine particle (Cl) is less than 5% by mass of the film, scratch resistance and abrasion resistance. Both of the corrosion resistance are insufficient. When the silica fine particles (Cl) exceeds 35% by mass, the amount of fine particles is too much compared to the resin (B1), and the wetting, toughness and strength of the film are lowered, and the corrosion resistance and work adhesion are insufficient. .

In the outermost layer film of the present invention, in addition to silica fine particles (Cl), ZrO ₂ (zirconia) and TiO ₂ (titania) having the same hardness as silica, harder than silica, and scratch resistance of the film Al ₂ O ₃ (alumina) -based minerals such as alumina, corundum, sapphire, ruby, BeO (beryllia), SiC (silicon carbide, carborundum), TiC (titanium) Hard ceramic fine particles such as carbide), WC (tungsten carbide), and Si ₃ N ₄ (silicon nitride) may be added. However, as already mentioned, the latter hard ceramic fine particles are often expensive, and the specific gravity is higher than that of the silica fine particles, and it is difficult to uniformly disperse them in an aqueous paint for forming a film. Since the effect of improving the corrosion resistance of the film is not high, the addition to the uppermost film should be minimized.

  The outermost layer film of the present invention preferably further contains a solid lubricant for improving slidability. By containing a solid lubricant, the lubricity of the outermost layer film is improved, workability is improved when the multi-layer film-coated metal sheet of the present invention is press-molded, and it is prevented from being wrinkled. It is effective in preventing abrasion scratches.

  The solid lubricant is not particularly limited, and examples thereof include known fluorine-based, hydrocarbon-based, fatty acid amide-based, ester-based, alcohol-based, metal soap-based and inorganic solid lubricants. As a selection criterion for lubricating additives to improve workability, it is important to select a lubricant that exists on the surface of the film rather than being dispersed in the outermost layer film formed. If it is an agent, the friction between the metal plate surface and the mold can be reduced during press molding, and the lubricating effect can be maximized. That is, when the lubricant is dispersed and present in the outermost layer film, the surface friction coefficient is increased, so the film is easily broken, and powdery substances are peeled and deposited, resulting in poor appearance and processability. Cause a drop. As the lubricant that exists on the surface of the film, a lubricant that is incompatible with the resin constituting the main body of the outermost layer film and has a small surface energy may be selected.

  From this point of view, a polyolefin wax made of polyethylene, polyethylene oxide, or the like is preferable because it lowers the dynamic friction coefficient on the surface of the film to increase workability, and suppresses breakage or peeling of the film to improve post-processing corrosion resistance. Used. At the time of processing, since the film temperature rises due to the deformation heat and frictional heat of the material, the melting point of the wax is more preferably 70 to 160 ° C. If the melting point is less than 70 ° C., it may be softened and melted during processing and an excellent workability improvement effect as a solid lubricant may not be obtained. In addition, wax particles having a melting point exceeding 160 ° C. are difficult to plastically deform during processing, and a sufficient workability improvement effect may not be obtained.

  The particle diameter of these waxes is preferably 0.1 to 5 μm. When the diameter is less than 0.1 μm, there is a possibility that sufficient workability improvement effect cannot be obtained. If the thickness exceeds 5 μm, it is too large for the preferred film thickness of the present invention, so that there is a possibility that the distribution of wax particles in the vicinity of the film surface becomes non-uniform or drops off from the film.

  The solid lubricant is preferably contained in an amount of 1 to 40 parts by mass with respect to 100 parts by mass of the outermost layer film. If the amount is less than 1 part by mass, the effect of improving the workability is small. On the other hand, if the amount exceeds 40 parts by mass, the amount of lubricant in the film is too large, and the fineness and adhesion of the film are impaired, resulting in corrosion resistance and work adhesion. Etc. may decrease.

  In order to improve the corrosion resistance and work adhesion of the outermost layer film of the present invention, various crosslinking agents described in the section of <Lowermost layer film> may be added to the water-based paint for forming the outermost layer film. Good. However, the addition amount is limited to a range that maintains the scratch resistance, wear resistance, and other necessary functions required for the outermost layer film. In order to raise the corrosion resistance and work adhesion of the outermost layer film, the polyphenol compound (D), phosphoric acid, hexafluorometal acid (E), phosphate compound ( F), or two or more of these various compounds may be included. The high-hardness resin (J) in the outermost layer film and the resins (A1) and (A2) in the lowermost layer film, such as water-containing (wet) film after coating, Structural analysis of resins that have been cross-linked and polymerized by UV irradiation, electron beam irradiation, heating, etc., and have become difficult to dissolve in solvents and water, include FT-IR spectra (high sensitivity reflection method) of coatings and thermal decomposition of coatings. GC-MS can be used. Among these, pyrolysis GC-MS separates fragment ions generated by pyrolyzing organic compounds (resins, organic additives, etc.) in the film into their respective molecular weight components by gas chromatography, and mass analysis of these fragment ions This is a method for identification and quantification by means of.

Fragment ions contained in the decomposition product gas are generated by selective cleavage or further cleavage of weak bonds in organic compounds such as resins, and their structure and relative mass reflect the skeleton of the original organic compound. Therefore, these can be analyzed as clues, and identification and quantification of resins and organic additives can be performed.

In the present invention, the adhesion amount of the outermost layer coating to adopt a configuration mainly composed of the high rigid resin (J) is preferably from ^{0.2~3g / m 2, 0.4~2g / m} 2 is particularly preferred. If it is less than 0.2 g / m ² , the film is too thin, and the desired scratch resistance and wear resistance may not be obtained. On the other hand, if it exceeds 3 g / m ² , the hard outermost layer film is too thick, cracks may occur during processing, and the corrosion resistance of the processed part may be insufficient, or the cost may increase.

  The multi-layer coated metal plate of the present invention has no deep scratches reaching the metal surface after performing a dry steel wool sliding test on the surface, and a wet cleanser sliding test on another part of the surface. It is preferable that no deep scratches reach the metal surface after performing the coating, and the film peeling area by the peeling test after the Erichsen processing is less than 10% of the top area. The dry steel wool sliding test and the wet cleanser sliding test described here are the same as the test methods described in the section <Film of outermost layer>. Moreover, the peeling test after Erichsen processing is performed by the method shown below.

  A test piece of 50 × 100 mm size was cut out from the metal plate and subjected to an overhang process of 7 mm height from the back side of the multi-layer coating surface with an Erichsen test machine, and the cellophane (registered trademark) adhesive tape (Nichiban Co., Ltd.) A cellophane tape (registered trademark)) was pressed and peeled off rapidly. The peeled tape is affixed to black Kent paper and the presence or absence of the film adhering to the adhesive surface is observed with the naked eye, and the film peeling area relative to the top area is determined.

<Intermediate layer film>
In the present invention, the outermost layer film comprising the high-hardness resin (J) as the main component provides excellent scratch resistance and wear resistance, and the lowermost layer film comprising the heat-deposited resin as the main component provides excellent corrosion resistance and processing. In the case where the adhesiveness is exhibited but the necessary functions cannot be shared by only these two layers, an intermediate layer film sandwiched between them may be provided. As long as such a film of the intermediate layer is in close contact with the adjacent films of the upper and lower layers and expresses a desired function, the type and composition of the main constituent components of the intermediate layer film, the number of intermediate layers, The formation method in particular on the metal surface of the multilayer film containing a layer is not limited. However, when using a wet-on-wet coating method or a multi-layer simultaneous coating method instead of a sequential coating method as a method for forming a multilayer film including an intermediate layer on a metal surface, an ultraviolet coating is used as an aqueous coating for forming the intermediate layer. Those containing a curable resin are undesirable in the present invention. This is because when UV-curing intermediate layers are included, UV coating can be sufficiently cured by sequential coating methods, but wet-on-wet coating methods and multilayer simultaneous coating methods may not be sufficiently UV-cured as described below. Because there is. In the sequential coating method, from the bottom layer to the top layer through the intermediate layer, each layer is heated and dried or further irradiated with ultraviolet rays to coat the coating, so UV rays are directly applied to the UV curable intermediate layer. And sufficient UV curing is possible. However, in the wet-on-wet coating method and multilayer simultaneous coating method, the laminated state from the lowest layer to the outermost layer is formed on a metal plate in a wet (wet) state, and then all layers are heated and dried together. When an ultraviolet curable layer is included, it is necessary to irradiate ultraviolet rays from above the outermost layer after drying. Therefore, in particular, when an ultraviolet curable intermediate layer is included, a part of the ultraviolet rays irradiated to the outermost surface is absorbed until the intermediate layer is absorbed, the ultraviolet energy is attenuated, and the ultraviolet curing of the intermediate layer becomes insufficient. there is a possibility. However, in electron beam curing, the energy of the electron beam used for industrial electron beam irradiation is several thousand to several tens of thousands times that of ultraviolet irradiation, and the depth at which the electron beam penetrates the resin film is several tens to several hundreds g. because the / m ² also, even if in multilayer-coated metal sheet according to the present invention including an intermediate layer of electron beam curing, the intermediate layer by electron beam irradiation from the top surface is sufficiently cured. Here, as described above, the multi-layer simultaneous coating method is a method in which a plurality of layers of coating liquid are simultaneously applied to a metal surface in a laminated state using a slide curtain coater or a slot die coater, and then the solvent in the multilayer coating liquid is simultaneously applied. This is a method of drying and film formation. The wet-on-wet coating method is a method of applying a coating liquid on a metal plate and then applying another coating liquid on the wet state before the coating liquid dries, In this method, the solvent inside is simultaneously dried to form a film.

  In the case of providing an intermediate layer in the present invention, in order to raise the corrosion resistance and work adhesion of the intermediate layer film, the various crosslinking agents described in the section of <Lowermost layer film> are applied to the water-based paint for forming the intermediate layer. It may be added. However, the addition amount is limited to a range that maintains the film function required for the intermediate layer. Further, in order to raise the corrosion resistance and work adhesion, the intermediate layer film is composed of the polyphenol compound (D), phosphoric acid, hexafluorometal acid (E), and phosphate compound (described in the section of the lowermost layer film). F), metal oxide fine particles (G) composed of one or more of Si, Ti, Al, and Zr, or two or more of these various compounds may be contained.

In the present invention, the adhesion amount of the intermediate layer film is preferably 0 to 3 g / m ² , particularly preferably 0.05 to ² g / m ² as the total adhesion amount of the entire intermediate layer. If it exceeds 3 g / m ² , the film may be too thick and the cost may increase.

<Preparation of water-based paint>
Various additives may be added to the water-based paint containing the water-based resin used to form each layer of the multilayer coating of the present invention as long as the water-based property and coating property of the paint are not impaired. . For example, an organic solvent, a defoaming agent, an anti-settling agent, a leveling agent, a surfactant such as a wetting agent, a thickener, and the like may be added. Moreover, you may add a coloring pigment, dye, etc. for improving designability, such as a conductive pigment for weldability improvement.

  Since the paint used to form the multilayer film of the present invention is an aqueous paint, it has a high surface tension and poor wettability to the coated surface compared to the solvent-based paint, and a predetermined amount of coating is applied to the coated surface. In some cases, uniform paintability may not be obtained. However, in order to ensure high processing adhesion and performance such as corrosion resistance, it is indispensable that uniform coating is performed on the surface to be coated. For this reason, it is preferable to add a wetting agent or a thickener among the additives. Examples of the wetting agent include known surfactants that lower the surface tension, such as fluorine and silicon. Among these compounds, it is particularly preferable to add 0.05 to 0.5 parts by mass of an acetylene glycol-alcohol type surfactant having 0 to 20 moles of added ethylene oxide with respect to 100 parts by mass of the aqueous paint. preferable. The acetylene glycol-alcohol surfactant is characterized by a high wetting rate and a defoaming effect at the same time. On the other hand, fluorine-based and silicon-based surfactants are excellent in surface tension reducing ability, but have low wetting speed and inferior defoaming property. It is not suitable for the water-based paint used in the above.

  Thickener is a measure for when sufficient surface coverage cannot be obtained with only a wetting agent on the surface of the surface to be coated, or when the required coating thickness cannot be ensured because the viscosity of the water-based paint is too low. May be added as. Since the water-based paint used for film formation of the present invention is usually applied to an object to be coated at high speed, a thixotropic (thixotropic) thickener typified by a cellulose-based coating condition is subject to high-speed shear stress. Then the effect is small. It is known that thickeners exhibiting Newtonian viscosity are suitable under such coating conditions. When adding a thickener to the water-based paint used for film formation of the present invention, a thickener having an ether-urethane skeleton having a molecular weight of 1000 to 20000 is particularly preferred. Usually, when an additive is added to a paint, the original performance is often lowered. However, since this thickener is difficult to hydrolyze, the influence when remaining in a film after film formation is very small. The amount added depends on the coating conditions, and is usually 0.01 to 0.2 parts by mass with respect to 100 parts by mass of the resin of the aqueous paint. If the amount is less than 0.01 parts by weight, the thickening effect is small. On the other hand, if the amount exceeds 0.2 parts by weight, the coating viscosity becomes too high, which not only hinders the coatability, but also results in the processing adhesion of the film. And there is a high possibility that the corrosion resistance will decrease.

  The properties of the water-based paint used to form the multilayer film of the present invention vary depending on the coating conditions of the lowermost layer, the intermediate layer, and the outermost layer, but the non-volatile content concentration is 15 to 30% by mass, the viscosity is 10 to 50 cps, and the surface tension is It is desirable to adjust to 80 dyne / cm or less. This is because it is easy to control the target coating amount, and it is easy to obtain a uniform film thickness with no unevenness in appearance and paint.

<Method for forming multilayer coating>
In the present invention, the method for forming the multilayer coating on the metal plate is not particularly limited, but there is a method to be recommended. Specific coating methods and coating conditions for multilayer coatings, and preferable ones among them, aqueous coating and drying processes, and ultraviolet rays that radicalize and cure the outermost layer of multilayer coatings after drying with ultraviolet rays or electron beams Or it divides and demonstrates to an electron beam irradiation process.

(Water-based paint painting and drying)
In the present invention, as a method for painting and drying a water-based paint, for example, a lowermost layer on a metal plate by a known coating method such as roll coating, groove roll coating, curtain flow coating, roller curtain coating, dipping (dip), air knife drawing, etc. Apply the coating and dry the water-containing (wet) film, and then repeat the coating and drying one layer at a time until the outermost layer (through the application and drying of the intermediate layer if an intermediate layer is provided). A multi-layered film may be formed by the above method, but a preferable method is to form a multi-layered film (wet) including a water-containing intermediate layer from the lowermost layer to the outermost layer. It is a dry wet-on-wet coating method or a multilayer simultaneous coating method. This is because, in terms of the performance of the multi-layer coated metal sheet, when wet-on-wet coating method or multilayer simultaneous coating method is used to form a film, a part of the resin chain in the layer at the interface of each layer containing water (wet) Diffuses and entangles in layers adjacent to each other, so that the interlayer adhesion after dry film formation becomes strong. Therefore, even if severe processing deformation is given to the multi-layer coated metal sheet of the present invention, the outermost layer mainly composed of a hard resin that is hard and difficult to stretch (J is an intermediate layer between the outermost layer and the lowermost layer) In some cases, through those closely contacting each other), the deformation of the lowermost layer having excellent work adhesion to metal is well followed, and as a result, the entire multilayer film exhibits excellent work deformability. In addition, in the wet-on-wet coating method or the multilayer simultaneous coating method, all layers can be formed under the same heating condition and heat input history regardless of the number of layers of the multilayer coating. For this reason, performance degradation due to excessive heat input, which is often seen with sequential coating methods that repeat heating and drying (decrease in strength due to thermal degradation such as thermal decomposition, resin chain breakage, and heat oxidation), decrease in corrosion resistance due to decrease in film density, and yellowing of the film Etc.), and a multi-layer coated metal plate with higher performance than the sequential coating method can be obtained.

  In terms of manufacturing process, if the film is formed by wet-on-wet coating method or multi-layer simultaneous coating method, it can be formed in one drying process regardless of the number of layers in the multilayer coating. Compared to the sequential coating method that requires painting and drying, the manufacturing process can be greatly shortened and simplified, and the equipment and running costs can be greatly reduced.

  As a wet-on-wet coating method that can be used in the present invention, for example, a metal by a known coating method such as the roll coat, groove roll coat, curtain flow coat, roller curtain coat, dipping (dip), air knife drawing, etc. Curtain flow coat, roller curtain coat, sliding curtain coat, slot die coat that can be applied on the board without drying the water-containing (wet) layer without contacting the coated surface. It is possible to use a method in which the obtained water-containing laminated film is simultaneously heated and dried to form a film at the same time by a known coating method such as the above. Also, as a multi-layer simultaneous coating method, a plurality of water-based paint thin films are sequentially extruded from a slot (elongated groove) on a slid (slide) surface of a coder, for example, as in a multi-layer slide curtain coat, and a stable composite in a water-containing state. A method can be used in which a laminar flow is formed and applied to a metal surface, and then all layers are heated and dried and cured simultaneously to form a film. FIG. 1 shows a schematic diagram of a three-layer sliding curtain coder as an example of a multilayer sliding curtain coder applicable to the production of the multilayer coated metal sheet of the present invention. Three types of water-based paints 1 are metered by a gear pump 2 and extruded sequentially from slots 4 provided at regular intervals along the flow direction of the slide surface 3 to form a stable three-layer flow 5 on the slide surface. The lip 6 at the tip of the slide part is dropped onto the metal plate 8 that travels as the curtain 7. Therefore, as a method of forming the multilayer film of the present invention on the metal surface, the coating of each layer from the lowermost layer to the outermost layer in contact with the metal surface in a wet (wet) state, sequentially or simultaneously, a process of multilayer coating (Water-based wet-on-wet coating or multi-layer simultaneous coating process), drying process that heats and drys moisture and volatile components of water-containing multi-layer film at the same time, and the outermost layer film of the multi-layer film after drying Or it is preferable to form by the method of including the ultraviolet-ray or electron beam irradiation process which carries out radical polymerization with an electron beam and forms into a film in the order listed.

In the present invention, it is preferable to apply the water-based paint so that the total adhesion amount of the multilayer coating after drying is in the range of 0.3 to 6 g / m ² . If the total adhesion amount is less than 0.3 g / m ² , there is a high possibility that the processed portion corrosion resistance will be insufficient. If it exceeds 6 g / m ² , the scratch resistance, abrasion resistance, and work adhesion are saturated, and the amount of water-based paint used is large, which is uneconomical. Moreover, it becomes easy to block while storing the multilayer coating metal plate of this invention in piles.

  In the present invention, it is preferable to heat and dry in a hot air furnace, a near infrared furnace, a far infrared furnace, an electric furnace, a combustion furnace, an induction heating furnace or the like immediately after applying a water-based paint.

  When applying by wet-on-wet coating method or multi-layer simultaneous coating method, heating is performed to react with the aqueous resin, crosslinking agent, silane coupling agent, etc. contained in each layer to form a multilayer film with the desired performance. The metal surface temperature at the time (Peak Metal Temperature) should be adjusted in the range of 80 to 200 ° C, preferably 120 to 160 ° C. When the ultimate plate temperature is lower than 80 ° C., the melting, reflow and crosslinking reaction of the aqueous resin (a1) used for forming the lowermost layer film is insufficient, and the desired film performance may not be obtained. When the temperature exceeds 200 ° C., many of the aqueous resin (a1) used for forming the lowermost layer film and the aqueous polymerizable hydrocarbon (b1) used for forming the outermost layer film are thermally decomposed or thermally oxidized. For this reason, the performance of the film is reduced. When the metal surface temperature is in the range of 120 to 160 ° C., melting and crosslinking reactions proceed favorably with many resins, and desired film performance is obtained. When the multilayer coating of the present invention is applied by a wet-on-wet coating method or a multilayer simultaneous coating method, usually the coating is heated and dried, and then cured by irradiating the outermost layer coating with ultraviolet rays or an electron beam, water-cooled, Cool by air cooling or other methods.

  When applying one layer at a time by coating methods such as roll coat, groove roll coat, curtain flow coat, roller curtain coat, dipping (dip), air knife drawing, etc., in the dry film formation process after each layer application, the bottom layer, intermediate layer, It is possible to set the metal surface temperature suitable for the dry film formation of the outermost layer. Since the lowermost layer film is mainly formed by a cross-linking reaction of a heat-deposited resin, it is preferable to sufficiently cross-link at a metal surface arrival temperature of 120 to 160 ° C. in the dry film forming step. On the other hand, since the outermost layer film is cured and formed mainly from radicals generated by irradiation with ultraviolet rays or electron beams, the drying temperature may be lower than that in the case of a heat-deposited resin. In the dry film-forming step of the outermost layer film, it is preferable to irradiate ultraviolet rays or electron beams after evaporating most of moisture and volatile components at a relatively low metal surface arrival temperature of about 80 to 120 ° C. Also, when an intermediate layer film is interposed between the lowermost layer and the outermost layer film, 120 to 160 ° C. is sufficient as in the case of the lowermost layer film if the main component of the intermediate layer is a heat-deposited resin. It is preferable to carry out a crosslinking reaction.

(Curing the outermost layer by UV irradiation)
The UV irradiation for curing the UV curable resin by radical polymerization with UV is usually performed in an air atmosphere, an inert gas atmosphere, a mixed atmosphere of air and an inert gas, etc. Then, it is preferable to irradiate with ultraviolet rays in an atmosphere and inert gas mixed atmosphere in which the oxygen concentration is adjusted to 10% by volume or less, or in an inert gas atmosphere. This is because oxygen is an inhibitor of radical polymerization, and therefore, when the atmospheric oxygen concentration at the time of ultraviolet irradiation is low, there is little deactivation or inhibition of crosslinking reaction due to addition of oxygen to the generated radical, and the aqueous polymerizable hydrocarbon used in the present invention. (B1) is sufficiently polymerized through radical polymerization and crosslinking, and the formation of the resin (B1) is promoted. As a result, the outermost layer film is more resistant to scratches and abrasion than in the case of ultraviolet curing in the air atmosphere. This is because it improves.

  Examples of the inert gas used here include nitrogen gas, carbon dioxide gas, argon gas, and mixed gas thereof.

  The ultraviolet light source can be irradiated with ultraviolet rays by using, for example, a metal vapor discharge high pressure mercury lamp, a metal halide lamp, a rare gas discharge xenon lamp, an electrodeless lamp using microwaves, or the like. Any lamp may be used as long as the outermost layer of the multilayer coating of the present invention can be sufficiently cured and desired scratch resistance and abrasion resistance can be obtained. In general, the peak illuminance and integrated light intensity of ultraviolet rays received by the film influence the curability of the film, but the outermost layer of the multilayer film of the present invention can be sufficiently cured, and the desired scratch resistance and abrasion resistance can be obtained. If it can be obtained, the irradiation condition of ultraviolet rays is not particularly limited.

(Curing outermost layer and intermediate layer by electron beam irradiation)
In the electron beam curing of the outermost layer film of the present invention, or the electron beam simultaneous curing of the outermost layer film and the intermediate layer film, normal electron beam irradiation used in the fields of printing, painting, film coating, packaging, sterilization, etc. An apparatus can be used. These are accelerated by applying a high voltage to thermoelectrons generated from a hot filament in a high vacuum, and the resulting electron flow is taken out in an inert gas atmosphere and irradiated to a polymerizable substance. In the multi-layer coated metal sheet of the present invention, the outermost layer of the electron beam curable type or the intermediate layer of the electron beam curable type can be sufficiently cured, and desired scratch resistance and abrasion resistance can be obtained. Any device may be used. In general, the acceleration voltage of the electron beam absorbed by the resin film affects the depth of penetration of the electron beam through the resin film, and the absorbed dose affects the polymerization rate (curability of the film). The irradiation condition of the electron beam is not particularly limited as long as the outermost layer of the layer film can be sufficiently cured and desired scratch resistance and wear resistance can be obtained. However, in the case of radical polymerization using an electron beam, even if a small amount of oxygen is present, deactivation or cross-linking reaction inhibition occurs due to addition of oxygen to the generated radical, and curing becomes insufficient, so that the oxygen concentration is less than 500 ppm. It is preferable to perform electron beam irradiation in an active gas atmosphere. Examples of the inert gas used here include nitrogen gas, carbon dioxide gas, argon gas, and mixed gas thereof.

Hereinafter, the present invention will be described specifically by way of examples.
[Metal plate for coating]
Prepare the following galvanized steel sheets M1 to M4, immerse them in an aqueous solution of an aqueous degreasing agent (FC-4480 manufactured by Nihon Parkerizing Co., Ltd.), degrease the surface, and then wash and dry to coat the multilayer coating. A metal plate was used.

M1: Electrogalvanized steel sheet (Shin Nippon Steel Co., Ltd. gin coat, thickness 0.8mm, plating thickness approx. 2.8μm)
M2: Electric Zn-Ni alloy plated steel sheet (Zinclite manufactured by Nippon Steel Corp., thickness 0.8mm, plating thickness approx. 2.8μm)
M3: Hot dip galvanized steel sheet (Shin Nippon Steel Co., Ltd. silver zinc, plate thickness 0.8mm, plating thickness about 7μm)
M4: Molten Zn-11% Al-3% Mg-0.2% Si alloy-plated steel sheet (Shin Nippon Steel Co., Ltd. Superdimer, thickness 0.8mm, plating thickness approx. 6μm)
[Water-based paint for forming the bottom film]

  As the water-based paint for forming the lowermost layer film, the following water-based resin (a1), silane coupling agent (s), polyphenol compound (D), phosphoric acid or hexafluorometal acid (E), phosphate compound (F ) And metal oxide fine particles (G) were combined to prepare an aqueous paint for forming the lowermost layer film.

(Water-based resin (a1))
a11: Water-based epoxy resin (Adeka Resin EM-0436 manufactured by ADEKA Co., Ltd.)
a12: Water-based polyester resin (DIC Corporation Finetex ES-850)
a13: Water-based polyurethane resin (Adekabon titer HUX680 manufactured by ADEKA Co., Ltd.)
a14: Aqueous acrylic resin (Boncoat SFC-65, manufactured by DIC Corporation)
(Silane coupling agent (s))
sl: 3-glycidoxypropyltrimethoxysilane (KBM-403 manufactured by Shin-Etsu Chemical Co., Ltd.)
s2: 3-aminopropyltrimethoxysilane (KBM-903 manufactured by Shin-Etsu Chemical Co., Ltd.)
s3: 3-mercaptopropyltrimethoxysilane (KBM-803 manufactured by Shin-Etsu Chemical Co., Ltd.)
(Polyphenol compound (D))
D1: Tannic acid (tannic acid AD manufactured by Fuji Chemical Industry Co., Ltd.)
D2: Gallic acid (Kanto Chemical Co., Ltd. Deer grade 1 gallic acid monohydrate)
(Phosphoric acid or hexafluorometal acid (E))
E1: Orthophosphoric acid (Kanto Chemical Co., Ltd. special grade reagent purity 85% phosphoric acid)
E2: Hexafluorotitanic acid (Wako Pure Chemical Industries, Ltd. Reagent Hexafluorotitanic acid 60% aqueous solution)
E3: Hexafluorozirconic acid (Wako Pure Chemical Industries, Ltd. Reagent Hexafluorozirconic acid 20% aqueous solution)
(Phosphate compound (F))
F1: Aluminum dihydrogen phosphate (Aluminum biphosphate manufactured by Yoneyama Chemical Co., Ltd.)
F2: Magnesium dihydrogen phosphate (magnesium biphosphate manufactured by Yoneyama Chemical Co., Ltd.)
F3: Manganese dihydrogen phosphate (manufactured by Yoneyama Chemical Co., Ltd.)
(Metal oxide fine particles (G))
G1: Silica fine particles (Snowtex-O, manufactured by Nissan Chemical Industries, Ltd.)
G2: Zirconia fine particles (ZSL-10T manufactured by Daiichi Rare Element Chemical Industry Co., Ltd.)
G3: Alumina fine particles (Alumina sol-100 manufactured by Nissan Chemical Industries, Ltd.)
Table 1 shows the type and content of each drug contained in the water-based paint (a) for forming the lowermost layer film. The content of the drug indicates how much non-volatile content of the other drug is contained with respect to 100 parts by mass of the nonvolatile content of the aqueous resin (a1). The concentration of non-volatiles contained in the water-based paint (a) for forming the lowermost layer film is set to the desired lower layer film adhesion amount after drying the film, or to stabilize the flow of the water-containing (wet) lowermost layer during simultaneous multi-layer coating , Adjusted as appropriate. In addition, as described in the section of “Background Art”, “nonvolatile content” in the present specification volatilizes low molecular weight compounds (such as water and solvents) blended as a solvent in paints and compositions. It means the component that remains afterwards.

  Among the paints shown in Table 1, 5b, 20b, 21b, and 26b have a total content of the aqueous resin (a1) and the silane coupling agent (s) of less than 50% by mass of the whole paint non-volatile content. Therefore, in the film obtained by applying these paints to the metal plate, the total amount of the resins (A1) and (A2) to be produced is less than 50% by mass of the film, so that it is not the lowermost film of the present invention.

[Water-based paint for forming the outermost layer film by UV curing]
As the water-based paint for forming the outermost layer film by ultraviolet curing, the following water-soluble polymerizable hydrocarbon (b1), photocleavable polymerization initiator (P), or silica fine particles (Cl) and solid lubricant (H) are used. A combination and a water-based paint for forming the outermost layer film were prepared.

(Aqueous polymerizable hydrocarbon (b1))
b11: Aqueous acrylic resin having a carbon-carbon double bond group having a methylidene group (Laromer LR8765, aliphatic epoxy acrylate manufactured by BASF)
b12: Aqueous polyurethane-based resin having a carbon-carbon double bond group having a methylidene group (Laromer LR8949, aliphatic urethane disperse rayon manufactured by BASF)
(Photocleavable polymerization initiator (P))
P5: 1-hydroxycyclohexyl phenyl ketone (Irgacurel 84 manufactured by Ciba Specialty Chemicals)
P6: 2,2-dimethyl-2-hydroxyacetophenone (Darocur 1173 manufactured by Ciba Specialty Chemicals)
P9: 2-methyl-1- [4- (methylthio) phenyl] -2- (4-morpholinyl) -1-propanone

(Irgacure907 manufactured by Ciba Specialty Chemicals)
Pl0: Bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide (Irgacure 819 manufactured by Ciba Specialty Chemicals)

  The above P5, P6, P9, and P10 are photocleavage-type polymerization initiations having the structures of the structural formulas (P5), (P6), (P9), and (P10) described in the section <Film of outermost layer>. It corresponds to each agent. These are the -parts of the photocleavable polymerization initiator (P) used in the present invention that are particularly preferred for use.

(Silica fine particles (Cl))
C11: Silica fine particles (Snowtex-N manufactured by Nissan Chemical Industries, Ltd.)
(Solid lubricant (H))
H1: Polyethylene wax (Chemipearl W500 manufactured by Mitsui Chemicals, Inc., particle size of about 2.5 μm)
H2: Polyethylene wax (Chemical WF640 manufactured by Mitsui Chemicals, Inc., particle size of about 1.0 μm)
Table 2 shows the type and content of each drug contained in the water-based paint for forming the outermost layer film by ultraviolet curing. The content of the drug indicates how much non-volatile content of the other drug is contained with respect to 100 parts by mass of the non-volatile content of the aqueous resin (b1). The concentration of non-volatile components contained in the water-based paint for forming the outermost layer film was appropriately adjusted in order to obtain a desired film adhesion amount after the film was dried, or to stabilize the flow of the wet (wet) outermost layer during multilayer simultaneous coating.

  Of the paints shown in Table 2, silica fine particles (Cl) are not included in the paints at 14t, 16t, 30t, and 32t, and the silica fine particles (C1) exceed 35% by mass of the paint non-volatile content at 15t and 31t. Therefore, in the outermost layer film obtained by applying these paints, the content of silica fine particles (Cl) is out of the range of 5 to 35% by mass of the film, and does not become the outermost layer film defined in the present invention.

[Water-based paint for forming outermost layer film by electron beam curing]
As the water-based paint for forming the outermost layer film by electron beam curing, the aqueous polymerizable hydrocarbon (b1) used in the section of [Water-based paint for forming the outermost layer film by ultraviolet curing], or further silica fine particles (Cl) The solid lubricant (H) was combined to prepare an aqueous coating for forming the outermost layer film.

  Table 7 shows the types and contents of the respective drugs contained in the water-based paint for forming the outermost layer film by electron beam curing. The content of the drug indicates how much non-volatile content of the other drug is contained with respect to 100 parts by mass of the non-volatile content of the aqueous resin (b1). The concentration of non-volatile components contained in the water-based paint for forming the outermost layer film was appropriately adjusted in order to obtain a desired film adhesion amount after the film was dried, or to stabilize the flow of the wet (wet) outermost layer during multilayer simultaneous coating.

  Of the paints shown in Table 7, silica fine particles (Cl) are not included in the paints at 40t, 42t, 50t, and 52t, and the silica fine particles (C1) exceed 35% by mass of the paint non-volatile content at 41t and 51t. Therefore, in the outermost layer film obtained by applying these paints, the content of silica fine particles (Cl) is out of the range of 5 to 35% by mass of the film, and does not become the outermost layer film defined in the present invention.

[Water-based paint for forming intermediate layer film]
In order to further improve the corrosion resistance of the processed part of the multilayer coating of the present invention, among the aqueous coatings for forming the lowermost layer shown in Table 1, an aqueous coating 34b mainly composed of an aqueous polyurethane resin a13 is used as an intermediate layer. It was also used as a water-based paint for film formation.

[Method of forming a multilayer coating]
(Method A: The outline of the forming process is multilayer simultaneous coating → drying → UV or electron beam curing)
After adjusting the non-volatile concentration of the lowermost layer and intermediate layer forming paint (Table 1) and the outermost layer forming paint (Table 2, Table 7) as appropriate for multi-layer simultaneous coating, use the multi-layer slide curtain coater on the metal plate. Two layers, the bottom layer and the top layer, or a total of three layers, the bottom layer, one intermediate layer, and the top layer, are applied simultaneously and dried in a hot air oven at a metal surface temperature of 150 ° C to form a multi-layer coating. Filmed. Non-volatile concentration of water-based paint so that both the multi-layer flow on the slide surface of the multi-layer slide curtain coater and the multi-layer flow after curtain formation are stable, and the amount of adhesion of each layer after drying is almost as intended. The types and amounts of surfactants and thickeners to be added to the paint, the feeding speed of the coder, and the curtain guide material were selected.

In the case of UV curing, after the above film formation, the oxygen concentration on the plate conveyor directly under the UV irradiation lamp is adjusted to about 5% by volume with an electrodeless microwave UV irradiation apparatus capable of purging with nitrogen gas. The multi-layer coating coated metal plate was placed on a conveyor with a lamp output of 240 W / cm and a metal plate passing speed of 20 m / min, and the outermost layer of the multi-layer coating was UV cured. At this time, the accumulated amount of light ultraviolet light receiving portions on the metal plate is subjected is about 200mJ / c m ^2. In the case of electron beam curing, after the above film formation, the oxygen concentration in the electron beam irradiation chamber is adjusted to about 200 ppm with a curtain beam type electron beam irradiation apparatus capable of purging nitrogen gas in the electron beam irradiation chamber, and then an irradiation dose of 40 kGy. The multi-layer coating coated metal plate was placed on a tray and passed through at a metal plate conveyance speed of 20 m / min, and the outermost layer of the multi-layer coating was electron beam cured.

The coating amount of the lowermost layer (g / m ² unit) is determined by applying only the lowermost layer in the multi-layer slide curtain coater, paint, coating conditions, and heat drying conditions used for the multi-layer simultaneous coating of Method A, It calculated from the mass difference of the metal plate after dry film formation. The coating amount (g / m ² unit) of the intermediate layer is the same as described above, and a metal plate coated with only the lowermost layer and the two layers of the lowermost layer and the intermediate layer are simultaneously coated and formed under the same coating conditions. It calculated from the mass difference of the obtained metal plate. The coating amount on the outermost layer was calculated in the same manner.

In Tables 3 to 5, Table 8, and Table 9, the metal plate used for coating by the A method, the lowermost layer, the intermediate layer, the combination of coating materials for forming the outermost layer, and the coating amount of each layer after film formation (g / m ² unit).

(Method B: The outline of the forming process is wet-on-wet coating → drying → UV or electron beam curing)
The non-volatile concentration of the lowermost layer and intermediate layer forming paint (Table 1) and the outermost layer forming paint (Tables 2 and 7) is appropriately adjusted for wet-on-wet coating, and a roll coater is applied to the metal plate. Apply the water-based paint for forming the lowermost layer film using it, and after applying the water-based paint for forming the outermost layer film using a curtain coater, without drying, use a hot air oven to reach the metal surface at 150 ° C. And dried to form a two-layer coating. When interposing an intermediate layer film (one layer) between the lowermost layer and the outermost layer film, apply a water-based paint for forming the lowermost layer film using a roll coater, and use a curtain coater without drying it. Then, a water-based paint for forming an intermediate layer film was overcoated. Without drying, this was coated with a water-based paint for forming the outermost layer film using another curtain coater, and then dried in a hot air oven at a metal surface temperature of 150 ° C. to form a three-layer film.

Next, the outermost layer of the multilayer coating was cured under the same ultraviolet or electron beam irradiation conditions as in Method A.
The coating amount of the lowermost layer (g / m ² unit) is determined by applying only the lowermost layer using the roll coater, paint, coating conditions, and heating / drying conditions used in the wet-on-wet coating of the B method. And the mass difference between the dried metal plate and the metal plate. The coating amount of the intermediate layer (g / m ² unit) is applied to the roll coater, curtain coater, paint, coating conditions, and heating / drying conditions used in the wet-on-wet coating described above. After weighing, the intermediate layer was overcoated and calculated from the difference in mass between the metal plates before the intermediate layer application and after the intermediate layer was formed. The coating amount on the outermost layer was calculated in the same manner.

Tables 6 and 10 show the metal plate used for coating by the B method, the lowermost layer, the intermediate layer, the combination of coating materials for forming the outermost layer, and the film adhesion amount (g / m ² unit) of each layer after film formation. Show.

(Method C: The outline of the formation process is the lowermost layer coating → drying (→ intermediate layer coating → drying) → the outermost layer coating → drying → ultraviolet or electron beam curing)
The non-volatile content of the lowermost layer and intermediate layer forming coating (Table 1) and the outermost layer forming coating (Table 2) is adjusted appropriately for sequential coating. First, the lowermost layer film is applied to the metal plate using a roll coater. A water-based paint for forming was applied, and this was dried at a metal surface temperature of 150 ° C. in a hot air oven, water-cooled and air-dried. Next, an aqueous coating for forming the outermost layer film was applied onto this single-layer coated metal plate using another roll coater and then dried at a metal surface temperature of 80 ° C. to form a two-layer film. When interposing an intermediate layer film (one layer) between the lowermost layer and the outermost layer film, first apply a water-based paint for forming the lowermost layer film using a roll coater, and dry at a metal surface temperature of 120 ° C. After water-cooling and air-drying, a water-based paint for forming an intermediate layer film was applied on top using another roll coater, dried again at a metal surface temperature of 150 ° C., water-cooled and air-dried. Next, an aqueous coating for forming the outermost layer film was applied onto the two-layer coated metal plate using another roll coater and then dried at a metal surface temperature of 80 ° C. to form a three-layer film.

Next, the outermost layer of the multilayer coating was cured under the same ultraviolet or electron beam irradiation conditions as in Method A.
The coating amount of each layer (g / m ² unit) is applied to each layer according to the roll coater, paint, coating conditions, and heat drying conditions used for sequential coating of the above-mentioned method C. It calculated from the mass difference of the metal plate before and after dry film formation.

Tables 6 and 10 show the metal plate used for painting by the C method, the lowermost layer, the intermediate layer, the combination of coating materials for forming the outermost layer, and the coating amount (g / m ² unit) of each layer after film formation. Show.

[Quantification of Si Atoms Forming —C—Si—O— Bond in Resin (A2)]
On the metal plate, only the lowermost layer film is formed by coating the lowermost layer film of the present invention example and the comparative example, the coater used for the film formation, the paint, the coating conditions, and the heating and drying conditions. Si atoms in the —C—Si—O— bond were quantified from the absorbance of the —C—Si—O— bond in the FT-IR absorption spectrum of the obtained film. The amount of Si forming a —C—Si—O— bond was expressed as a relative mass (unit of parts by mass) with respect to a total of 100 parts by mass of the resins (A1) and (A2) contained in the lowermost layer film. These results are shown in Tables 3-6 and Tables 8-10.

[Quantification of highly rigid resin (J)]
On the metal plate, a multi-layer coating consisting of the lowermost layer (intermediate layer) and the outermost layer coating was formed on the metal plate with the coater, paint, coating conditions, heat drying conditions, and curing conditions used in the multi-layer coating of the example of the present invention. . Reflux the multi-layer coating with MEK (methyl ethyl ketone) for 1 hour, unreacted aqueous resin (a1) remaining in the lowermost layer coating, unreacted aqueous polymerizable hydrocarbon (b1) remaining in the outermost layer coating, MEK-soluble components in the film such as a part of the remaining unreacted photocleavable polymerization initiator (P) were removed. The residue was further refluxed with n-hexane for 1 hour to remove n-hexane soluble components such as the remainder of the photocleavable polymerization initiator (P) that was not extracted with MEK. The highly rigid resin (J) in the outermost layer film was quantified by pyrolysis GC-MS of the residue after reflux. When the outermost layer film is obtained by UV curing, Rad of the photocured radical (Rad.) Of the UV-cured resin (B1) and (B1) a repeating unit constituting the resin chain ((B1) resin chain The aqueous polymerizable hydrocarbon (b1)) incorporated in the crosslinked structure was quantified, and the ultraviolet curable resin (B1) in the outermost layer film was quantified. Even when the outermost layer film was obtained by electron beam curing, the electron beam cured resin in the outermost layer film was quantified by the same method. These results are shown in Tables 3-6 and Tables 8-10.

  As described above, pyrolysis GC-MS separates fragment ions generated by pyrolyzing organic compounds (resins, organic additives, etc.) in the film into their respective molecular weight components using a gas chromatograph. This is a method for identifying and quantifying. Fragment ions contained in the decomposition product gas are generated by selective cleavage or further cleavage of weak bonds in organic compounds such as resins, and their structure and relative mass reflect the skeleton of the original organic compound. Therefore, these can be analyzed as clues, and identification and quantification of resins and organic additives can be performed.

[Performance evaluation]
Using the multilayer coating-coated metal plate prepared by the above method, a steel wool sliding test in a dry type and a cleanser sliding test in a wet type were performed for evaluation of scratch resistance and abrasion resistance. In addition, for processing adhesion evaluation and corrosion resistance evaluation, an Erichsen processing test and a salt spray test of a flat plate portion and an Erichsen processing portion were performed, respectively. Below, each test and the method of evaluation are shown. Tables 3 to 6 and Tables 8 to 10 show the evaluation results.

(Abrasion resistance, abrasion resistance evaluation 1: dry steel wool sliding test)
A test piece of 32 × 100 mm size was cut out from the metal plate. Cut # 0000 steel wool into a 50mm square and affix it to a rubber stopper (20mm diameter) attached to the head of a rubbing tester (DIC type rubbing tester type 1 manufactured by Riken Engineering Co., Ltd.) with a load of 1.56N / cm ² The test piece was pressed against the test piece, and a dry test was conducted with a sliding distance of 60 mm, 60 reciprocations / min, and 100 reciprocations. The surface of the surface that had been slid by dyeing the coating resin was visually observed, and a score of 3 or more was accepted according to the following evaluation criteria.

5: No scratches 4: Very shallow scratches that are difficult to identify without staining the coating resin 3: There are shallow scratches that do not reach the metal surface, but no deep scratches that reach the metal surface
2: Mixing shallow scratches and deep scratches reaching the metal surface
1: There is a deep scratch that reaches the surface of the metal plate over the entire sliding surface

(Abrasion resistance, abrasion resistance evaluation 2: wet cleanser sliding test)
A test piece of 32 × 100 mm size was cut out from the metal plate. Cut out felt (Yuzawaya Shoji Co., Ltd. one-touch felt RN-01) into a 40mm square and affix it to a rubber plug (20mm diameter) attached to the head of a rubbing tester (DIC type rubbing tester type 1 manufactured by Riken Engineering Co., Ltd.). After fixing with rubber bands, distilled water was sufficiently contained in the felt part, and dripping water was gently wiped off. To the test piece, 0.5 cc of a 5% silica-based mineral abrasive (a Kao Corporation homing cleanser diluted 10-fold with distilled water) was dropped, and the test piece was loaded at a load of 1.56 N / cm ^2. A sliding test was performed by pressing the material into a wet type, sliding distance of 60 mm, 60 reciprocations / minute, and 100 reciprocations. After the test piece was washed, the film resin was stained and the scratches on the sliding surface were observed with the naked eye.

5: No scratches 4: Very shallow scratches that are difficult to identify without staining the coating resin 3: There are shallow scratches that do not reach the metal surface, but no deep scratches that reach the metal surface 2: Shallow scratches and the metal surface Mixed deep scratches that reach the surface 1: Deep scratches that reach the surface of the metal plate over the entire surface

(Processing adhesion evaluation: Eriksen processing test)
A test piece of 50 × 100 mm size was cut out from the metal plate and subjected to an overhang process of 7 mm height from the back side of the multi-layer coating surface with an Erichsen tester, and the cellophane (registered trademark) adhesive tape (Nichiban ( A cellophane tape (registered trademark) manufactured by Co., Ltd.) was pressed and peeled off rapidly. The peeled tape is affixed to black Kent paper, and the presence or absence of the film adhering to the adhesive surface is observed with the naked eye. If the peeled area of the top film is less than 10% of the top area, it passes and 10% or more is peeled off. Passed.

(Corrosion resistance evaluation 1: Flat part SST)
Cut out a 50 x 100 mm size test piece from the metal plate, seal the end of the plate, perform a salt spray test in accordance with JIS-Z2371, and determine the area ratio of white rust after 72 hours according to the following evaluation criteria Measured and passed 3 or more.

6: No white rust generation 5: White rust generation area rate of less than 3% 4: White rust generation area rate of 3% or more and less than 5% 3: White rust generation area rate of 5% or more and less than 10% 2: White rust generation area rate of 10 % To less than 20% 1: White rust generation area ratio of 20% or more

(Corrosion resistance evaluation 1: Processing part SST)
Cut out a test piece of 50 x 100 mm size from the metal plate, apply an overhang process 7 mm high from the back side of the multi-layer coating surface with an Erichsen tester, seal the end of the plate, and then salt water in accordance with JIS-Z2371 A spray test was performed. Based on the following evaluation criteria, the white rust occurrence area ratio of the convex portion after 72 hours was measured, and 3 or more was regarded as acceptable.

6: No white rust generation 5: White rust generation area ratio less than 5% 4: White rust generation area ratio 5% or more and less than 10% 3: White rust generation area ratio 10% or more and less than 20% 2: White rust generation area ratio 20 % To less than 30% 1: White rust generation area rate of 30% or more

  In the coated metal plates of the examples of the present invention described in Tables 3 to 6 and Tables 8 to 10, excellent scratch resistance and wear resistance are provided regardless of the metal plate type, the coating type of each layer, and the formation method of the multilayer coating. It can be seen that excellent process adhesion and corrosion resistance can be obtained. This is presumably because the hard outermost layer film and the finest lowermost layer film share the functions well and contribute to the improvement of scratch resistance and wear resistance, and the improvement of work adhesion and corrosion resistance, respectively.

  On the other hand, when the outermost layer film itself is not formed (Comparative Example No. 10, 47, 79, 119, 137), the scratch resistance and wear resistance are poor, and when the lowermost layer film itself is not formed ( Comparative Examples Nos. 6, 43, 77, 115, 133, 151, 201, and 215) are poor in both processing adhesion and corrosion resistance.

  Even when both the outermost layer film and the lowermost layer film are formed, if any one of the films is not specified by the present invention, the performance evaluation fails. For example, when the outermost layer film does not contain silica fine particles (Cl) at all (Comparative Examples No. 91, 93, 107, 109, 186, 188, 196, 198), the scratch resistance and wear resistance are insufficient. Fail. When the silica fine particle (Cl) content exceeds 35% by mass of the coating (Comparative Examples No. 92, 108, 187, 197), the work adhesion is insufficient. Of the paints shown in Table 1, 5b, 20b, 21b, and 26b have a water-based resin (a1) content of less than 50% by mass of the whole paint non-volatile content. In the lowermost layer film (Comparative Examples No. 21, 36, 37, 58, 171 and 172) obtained in this way, the total of the resins (A1) and (A2) generated during film formation is less than 50% by mass of the film. As a result, the corrosion resistance of the multi-layer coating is insufficient, resulting in a failure.

  In the present invention example, in the case of a three-layer film having an intermediate layer between the lowermost layer and the outermost layer film, the corrosion resistance may be further improved as compared to the case without an intermediate layer (for example, Invention Example No. 42 and 55, Invention Examples No. 76 and 82, Invention Examples No. 112 and 125, No. 113 and 126, No. 114 and 127, Invention Examples No. 147 and 158, No. 150 159, No. 200 and 209, No. 214 and 223, etc.). This is because the silane coupling agent contained in the paint 34b used for forming the intermediate layer greatly contributed to the formation of a highly crosslinked structure with the coexisting resin (a1) and the enhancement of the interfacial adhesion with the upper and lower coating layers. This is probably because the corrosion resistance of the entire multilayer film has been raised.

Even if the adhesion amount of the lowermost layer film exceeds the preferable range of 0.01 to 3 g / m ² , the processed portion corrosion resistance is still at the acceptable level, but there was a tendency to slightly decrease compared to the case where it is in the preferable range (for example, Comparison of Invention Example No. 9 (adhesion amount 3.5 g / m ² ) with No. 2 and No. 8, Invention Example No. 46 (adhesion amount 3.7 g / m ² ) and No. 39 and No. 45 Comparative, Inventive example No.118 comparison with (adhesion amount 3.5 g / m ²⁾ and No.111 and No.117, the invention examples No.154 and (deposition amount 3.5g / m ²⁾ No.147 and No.153 Comparison of No. 204 (adhesion amount 3.5 g / m ² ) with No. 200 and No. 203). This is because if the coating amount exceeds 3 g / m ² , the coating cannot follow the deformation of the base metal plate during processing, and part of the metal surface peels off or cracks occur, resulting in corrosion resistance of the processed part. It is thought that it is somewhat lower. Even when the adhesion amount is slightly thick, as shown in the performance evaluation results of Nos. 9, 46, 118, 154, 204 and the like, the processing adhesion is still at the acceptable level of the present invention.

Similarly, beyond the 0.2 to 3 g / m ² in the range amount of adhering outermost layer coating is preferred, although the processing unit corrosion resistance is still acceptable level, compared to the case in the preferred range, it tends slightly to decrease (For example, Comparison between Invention Example No. 14 (adhesion amount 3.6 g / m ² ) and No. ² , 12, 13; Invention Example No. 51 (adhesion amount 3.8 g / m ² ) and No. 39, Comparison with 49, 50, Comparison with Invention Example No. 123 (adhesion amount 3.5 g / m ² ) and No. 111, 121, 122, No. 157 (adhesion amount 3.5 g / m ² ) and No. 147 Comparison). This is presumably because, when the coating amount exceeds 3 g / m ² , cracks are likely to occur in the hardest outermost layer coating during processing, and the corrosion resistance of the processed portion is slightly reduced accordingly. Even when the adhesion amount is slightly thick as described above, as shown in the performance evaluation results of No. 14, 51, 123, 157, etc., the work adhesion is still at the acceptable level of the present invention.

When the adhesion amount of the outermost layer film is less than the preferable range of 0.2 to 3 g / m ² , the scratch resistance and the wear resistance are still acceptable levels, but there was a tendency to slightly decrease compared to the preferable range. (For example, comparison between Invention Example No. 11 (adhesion amount 0.15 g / m ² ) and No. ² , 12, 13; Invention Example No. 48 (adhesion amount 0.15 g / m ² ) and No. 39, 49, Comparison with No. 50, Comparison between Invention Example No. 120 (adhesion amount 0.15 g / m ² ) and No. 111, 121, 122, Comparison between No. 155 (adhesion amount 0.15 g / m ² ) and No. 147, etc. ). This is presumably because when the adhesion amount of the outermost layer film is less than 0.2 g / m ² , the film is thin and it is difficult to maintain a high level of scratch resistance and wear resistance. Even when the adhesion amount is slightly thin as described above, as shown in the performance evaluation results of No. 11, 48, 120, 155, etc., the scratch resistance and wear resistance are still at the pass level of the present invention. is there.

  As described above, according to the present invention, there is provided a multi-layer coating-coated metal plate that is less likely to be scratched and worn even when subjected to strong sliding with a hard foreign object, and that is excellent in corrosion resistance and work adhesion. Can be provided. Until now, it has been difficult to produce thin film coated metal sheets with excellent scratch resistance, wear resistance, corrosion resistance, and work adhesion.For example, even if they have excellent scratch resistance and wear resistance, they can rust immediately. Applications that could not be applied due to loss of surface appearance and strength as structural members, and conversely, even if they have excellent corrosion resistance and work adhesion, they cannot be applied because the surface is immediately scratched or worn and damages the design. Can be widely used for various purposes.

Claims (17)

A metal plate in which at least a part of the surface is coated with a multilayer film in which two or more layers are laminated, and the lowermost film in contact with the metal surface of the multilayer film is an aqueous heating film-forming resin paint ( a) a coating obtained by applying a) to a metal surface and drying by heating; and a resin (A1) obtained by applying an aqueous resin (a1) to the metal surface and drying by heating in the coating; One of the derivatives (A2) represented by the following general formula (I) as a derivative is contained in a total amount of 50 to 100% by mass of the coating, and the outermost coating is a water-based resin coating. (J) is applied to the surface of the coating film, dried, and then cured by ultraviolet irradiation, electron beam irradiation, high temperature heating of 200 ° C. or higher, and the like, and a highly rigid resin (J) 50-95 mass% silica fine particles (C1) It characterized in that it contains 5 to 35 wt% of the film, multilayer-coated metal sheet.

(In the formula, A1 is a resin obtained by applying an aqueous resin (a1) to a metal surface and drying by heating, and Z- has 1 to 9 carbon atoms, 0 to 2 nitrogen atoms, and 0 to oxygen atoms. In the hydrocarbon chain of 2, the notation of “A1 to Z” indicates that A1 and Z are covalently bonded through the functional groups of both, —O— is an ether bond, and —OH group Is a hydroxyl group, -X group is a hydrolyzable alkoxy group having 1 to 3 carbon atoms, hydrolyzable halogeno group or hydrolyzable acetoxy group, and -R group is an alkyl group having 1 to 3 carbon atoms. And a, b, c, and d indicating the number of substituents are all integers of 0 to 3, and a + b + c + d = 3.) The aqueous resin paint (j) is an aqueous ultraviolet curable resin paint (b), and the highly rigid resin (J) is an ultraviolet curable resin (B1) represented by the following general formula (II). A multilayer coated metal sheet characterized by the above.

(Wherein, Rad is an adduct radical (Rad ·) for generating an ultraviolet light receiving cleavage of light cleavage type polymerization initiator, -X ¹ group is a hydrogen atom or a methyl group, -Y ¹ group is a hydrocarbon The —Z ¹ group is an anionic, cationic or nonionic hydrophilic group or a hydrocarbon group having the hydrophilic group.)   The resin component of the water-based paint (a) is one or two selected from water-based epoxy resins, water-based phenol resins, water-based polyester resins, water-based polyurethane resins, water-based (meth) acrylic resins, and water-based polyolefin resins. It is a seed | species or more, The multilayer coating metal plate in any one of Claims 1 and 2.   The sum of the resins (A1) and (A2) is formed in the lowermost layer of the multilayer coating in which Si atoms forming —C—Si—O— bonds in the resin (A2) are in contact with the metal surface. The multilayer coated metal sheet according to any one of claims 1 to 3, which is contained in an amount of 0.1 to 30 parts by mass with respect to 100 parts by mass. Multilayer-coated metal sheet according to claim 1 adhered amount of the lowermost layer film is 0.01 to 3 g / m ^2.   The multilayer coating according to any one of claims 1 to 5, wherein the lowermost layer coating contains 1 to 100 parts by mass of the polyphenol compound (D) with respect to 100 parts by mass in total of the resins (A1) and (A2). Metal plate.   The lowermost film is one or more acid components (E) selected from the group consisting of phosphoric acid and hexafluorometal acid with respect to a total of 100 parts by mass of the resins (A1) and (A2). It contains 0.1-100 weight part, The multilayer coating | coated metal plate in any one of Claims 1-6 characterized by the above-mentioned.   The metal plate according to claim 7, wherein the hexafluorometal acid contains one or more elements selected from the group consisting of Ti, Si, Zr, and Nb.   The said lowermost layer film | membrane contains 0.1-100 mass parts of phosphate compounds (F) with respect to a total of 100 mass parts of said resin (A1) and (A2). A multilayer coated metal sheet according to any one of the above.   10. The compound according to claim 9, wherein the phosphate compound (F) contains one or more elements selected from the group consisting of Mg, Mn, Al, Ca, and Ni as a cation component. Layer coated metal plate.   The resin (A1) and (A2) are obtained by forming the metal oxide fine particles (G) made of an oxide of one or more metals selected from the group consisting of Si, Ti, Al, and Zr as the lowermost layer film. The multilayer coated metal sheet according to any one of claims 1 to 10, which is contained in an amount of 0.1 to 100 parts by weight with respect to a total of 100 parts by weight. The radical addition compound Rad at the terminal of the ultraviolet curable resin (B1) is a terminal group having a structure represented by any of the following formulas (Rad1) to (Rad13). Multi-layer coated metal plate.

Wherein -Z ¹ group of UV cured resin (B1) is comprised of an aqueous epoxy resin, aqueous polyester resins, aqueous polyurethane resins, aqueous (meth) acrylic resin, aqueous amino resin, and aqueous silicone resin The multilayer coated metal sheet according to any one of claims 2 and 12, which is one or more selected from the group. In -X ¹ group is a hydrogen atom of the ultraviolet cured resin (B1), any one of claims 2, 12, 13, wherein the resin (B1) is a structure represented by the following general formula (III) 2. A multilayer coated metal plate according to 1.

(In the formula, Rad is an adduct of a radical (Rad.) Generated by ultraviolet light-receiving cleavage of a photocleavable polymerization initiator, -Y ¹ group is a hydrocarbon group, -Z ¹ group is an anionic type, It is a cationic or nonionic hydrophilic group or a hydrocarbon group having the hydrophilic group.) The multilayer coated metal sheet according to any one of claims 1, ² , and 12 to 14, wherein an adhesion amount of an outermost layer film of the multilayer film is 0.2 to 3 g / m2.   After performing a dry steel wool sliding test on the surface of the multi-layer coated metal sheet, and after having performed a wet cleanser sliding test on another part of the surface, without any deep scratches reaching the metal surface 16. The compound according to any one of claims 1 to 15, wherein there is no deep scratch reaching the metal surface, and a film peeling area by a peeling test after Erichsen processing is less than 10% of the top area. Layer coated metal plate.   It is a manufacturing method of the metal plate by which at least one part of the single side | surface or both front and back surfaces was coat | covered with the multilayer film in any one of Claims 1-16, Comprising: Each layer from the lowest layer in contact with the metal plate surface to the outermost layer The process of coating multiple layers sequentially or simultaneously in a wet (wet) state (water-based wet-on-wet coating or multi-layer simultaneous coating process), and the moisture and volatile content of the multilayered film in a wet state at the same time Manufacture of a multilayer coated metal sheet comprising a drying step for heating and drying and an ultraviolet ray or electron beam irradiation step for radical polymerization of the outermost layer film of the dried multilayer film with ultraviolet rays or an electron beam to form a film in the listed order. Method.

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