JP3872998B2 - Painted metal plate and squeezed iron can using the same - Google Patents

Description

【００６７】
塗装金属板の作成
実施例１〜１０及び比較例１〜９
上記製造例で得られた内面用塗料と外面用塗料を用い、後記表３に示す組み合わせにて各塗装金属板を作成した。該塗装金属板において、素材はりん酸クロメート処理を施された厚さ０．２８ｍｍの＃３００４アルミニウム材を使用し、まず、外面用塗料を表３に示す各乾燥塗布量になるようバーコーターにて塗装し１００℃で６０秒間焼付け乾燥を行った後、素材の反対側に内面用塗料を表３に示す各乾燥塗布量になるようバーコーターにて塗装し、素材最高到達温度が２７０℃になる条件で２０秒間焼付けを行なうことにより作成した。
【００６８】
各内面用塗料及び各外面用塗料から得られる塗膜の性能、および上記方法で得られた各塗装金属板について下記の試験方法に従って試験を行った。試験結果を後記表３に示す。
【００６９】
試験方法
Ｔｇ（℃）：バーコーターを用いて、各内面用及び外面用塗料を乾燥後の塗着量が１８０ｍｇ／１００ｃｍ２となるようにブリキ板に塗装し、素材最高到達温度が２７０℃になる条件で２０秒間焼付けを行った。得られた塗板を５ｍｍ×５ｍｍの大きさに切り、ＭＡＣ ＳＣＩＥＮＣＥ社製 ＴＭＡ−４０００装置を用いて、針入法（荷重１ｇ）でＴＭＡ曲線を測定し、変曲点前後の接線の交点をＴｇとして評価した。
【００７０】
６０℃伸び率：バーコーターを用いて、各内面用及び外面用塗料を乾燥後の塗着量が１８０ｍｇ／１００ｃｍ２となるようにブリキ板に塗装し、素材最高到達温度が２７０℃になる条件で２０秒間焼付けを行った。この塗膜を水銀アマルガム法ではがし、フリーフィルムを得た。このフィルムを５ｍｍ幅で３０ｍｍ長さに切り、上下５ｍｍをつかみ代として、島津製作所社製 オートグラフＡＧＳ−Ｈ装置を用いて６０℃雰囲気下、引張り速度５００ｍｍ／ｍｉｎで破断までの伸び率を測定した。
【００７１】
６０℃鉛筆硬度：各塗装金属板を６０℃に設定した加熱板の上に乗せ、表面温度計で試料表面が６０℃になったのを確認してから、ＪＩＳ Ｋ−５４００ ８．４．２（１９９０）に準拠して鉛筆引っ掻き試験を行った。評価は破れ法で行った。
【００７２】
６０℃動摩擦係数：東洋精機社製 ＦＲＩＣＴＩＯＮ ＴＥＳＴＥＲ ＴＲ−２装置の加熱板を６０℃に設定し、その上に各塗装金属板を乗せる。表面温度計で試料表面が６０℃になったのを確認してから、荷重２Ｋｇ，引張り速度１０００ｍｍ／ｍｉｎの条件で動摩擦係数を測定した。動摩擦係数が小さいほど潤滑性は良好である。
【００７３】
６０℃加圧粘着性：各塗装金属板を５ｃｍ×５ｃｍの大きさに切り、塗装面に所定の紙（クレシア社製 Ｋｌｅｅｎｅｘ Ｆａｃｉａｌ Ｔｉｓｓｕｅｓ）をかぶせ、６０℃の雰囲気中、３０Ｋｇ／ｃｍ２で２４時間加圧した後取り出し、室温に戻してから紙をはがし、その状態を評価した。
○ ：剥がすことができる
△ ：剥がせるが、塗膜に紙の繊維が残る
× ：剥がすことができない。
【００７４】
Ｄ＆Ｉ成形加工性：各塗装金属板をエリクセン社製 金属薄板深絞り試験機１４２型を使用し、ブランク径８２mmから以下の表に示す５段階の処理を順次行ない、最終的に絞り率＝約３７％、しごき率＝約６０％の絞りしごき加工を施した後、製缶性、外観及び被覆性を評価した。
【００７５】
【表２】

【００７６】
[製缶性] １０缶成形加工したうちの成形加工できた率から以下の基準で評価した。
◎ ：成功率１００％。
○ ：成功率９０％以上、１００％未満。
△ ：成功率５０％以上、９０％未満。
× ：成功率５０％未満。
[外観] 成形できたものについて、加工部の状態を目視で評価し、塗膜に異常が認められないものを○とした。
[被覆性] ２規定塩酸溶液９５部に硫酸銅５部を加えて溶解し、さらにアセトン１００部を混合して試験液を作成した。この試験液に加工した缶を６０秒間浸漬した後、水洗して缶を切り開き、内面の腐食の程度を目視評価した。
○ ：腐食が認められない。
○△：缶上部の最もしごき加工を受ける部位に一部腐食が認められる。
△ ：缶中部以上のしごき加工部ほぼ全面に腐食が認められる。
× ：明らかな塗膜欠陥があり、大きく腐食が起こっている。
【００７７】
【表３】

【００７８】
【発明の効果】
本発明の両面塗装金属板は塗膜の強度とスベリ性が適度に保たれたものであり、絞りしごき加工のような厳しい加工に十分耐えることができ、ＤＩ缶用のプレコート鋼板として特に適したものである。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a double-sided coated metal plate for cans, and more particularly to a coated metal plate that can withstand severe processing at high speed such as drawing and ironing (DI processing).
[0002]
[Prior art and problems]
Two-piece cans used for food cans, etc., depending on the manufacturing method, drawn and ironed cans (DI cans: Draw and Ironed Can), and drawn cans (DR cans: Drawn Can) that do not contain irons, There are redrawn cans (DRD cans) and DTR cans (Drawn Thin Redraw Cans). Of these, DI cans are widely used for positive pressure beverage cans such as beer and carbonated drinks due to their cosmetic properties and thin and light weight. However, in manufacturing DI cans, it is necessary to use a large amount of coolant, degrease, wash, surface treatment, spray coating the inner surface and bake and dry. The load on the environment was also great.
[0003]
In order to solve such a problem, various proposals have been made that can be made without coolant by using a coated steel plate previously coated with an organic coating, and that can be made without coolant and does not perform subsequent inner surface spray coating. Most of them are laminates of thermoplastic solid film on steel plate.
[0004]
For example, a biaxially stretched thermoplastic film is heat laminated to a metal plate directly or via an adhesive. JP-A 56-10451, JP-A 57-65463, etc. An example using a polyester film as a plastic film is disclosed. Further, instead of processing a thermoplastic resin into a film and laminating it on a metal plate, a method of thermally melting the resin and directly extruding and laminating it on the metal plate is disclosed in Japanese Patent Application Laid-Open No. 51-17988. Has been.
[0005]
However, once the resin is made into a film, the film has to be thickened to some extent in handling, and there is a problem that it is inferior in economic efficiency as compared with the conventional coating method because it is repeatedly heated and melted and cooled.
[0006]
On the other hand, the use of a pre-coated steel sheet pre-coated with a paint instead of a laminated steel sheet is also being studied, but there is a problem that a rugged process such as drawing and ironing is involved, and a film that can withstand it cannot be obtained.
[0007]
For example, although a method using a thermosetting resin is disclosed in Japanese Patent No. 2508799 as a post-processing method, it is a precondition that no ironing is applied, and it is difficult to withstand drawing ironing.
[0008]
An object of the present invention is to solve the above-mentioned problems, and to obtain a coated metal plate for a squeezed iron can that has excellent adhesion to the metal of the coating film, is strong, has good workability, and can withstand squeezing and ironing.
[0009]
[Means for Solving the Problems]
As a result of intensive studies to solve the above-mentioned problems, the present inventors have determined that the toughness (hardness), elongation rate and slippery enough to withstand heat generation near 60 ° C. due to continuous drawing and ironing on the film that becomes the inner surface of the can after processing. It can withstand squeezing and ironing by forming a film that can maintain (dynamic friction coefficient) and a film that can maintain sufficient hardness at 60 ° C on both sides of the metal plate. The present inventors have found that a can metal sheet for cans can be obtained and have completed the present invention.
[0010]
Thus, according to the present invention, a double-sided coated metal plate having a dry coating amount of 90-400 mg / 100 cm <2>, a glass transition temperature of 50-120 [deg.] C., and a 60 [deg.] C. Under the conditions, the pencil hardness is H or higher, the elongation is 200 to 600%, and the dynamic friction coefficient is 0.03 to 0.25. The dry coating amount of the film that becomes the outer surface of the can after processing is 15 to 150 mg / A coated metal plate for a squeezed iron can having a pencil hardness of H or higher under test conditions of 100 cm 2, glass transition temperature of 50 to 120 ° C. and 60 ° C. is provided.
[0011]
The present invention also provides a squeezed iron can obtained by squeezing and squeezing and processing the painted metal plate for a squeezed iron can.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
The coated metal plate of the present invention has a paint applied on both surfaces of a metal plate used for a squeezed iron can. On the surface that becomes the inner surface of the can after processing, a dry coating amount of 90 to 400, preferably 100 to A film having a dry coating amount of 15 to 150, preferably 30 to 100 mg / 100 cm <2> is formed on the surface that becomes 200 mg / 100 cm <2> and the outer surface of the can after processing. The type of paint applied to both sides of the metal plate may be the same or different, but usually the required performance differs between the can inner surface and the can outer surface, so the type of paint used It is better to be different.
[0013]
First, the paint used for the inner surface of the can and the outer surface of the can will be described.
[0014]
Can inner coating
Conventionally, epoxy-based paints have been used for can inner surface paints. Epoxy paints have high hardness and good adhesion to metals, but have the disadvantage of poor workability.
[0015]
As a result of repeated studies on the paint suitable for this application, the glass transition temperature of the film obtained therefrom is 50 to 120 ° C., preferably 60 to 100 ° C., and the test condition of 60 ° C. is pencil hardness H or more and elongation. It has been found that it is suitable that the ratio is in the range of 200-600%, preferably 250-500% and the dynamic friction coefficient 0.03-0.25, preferably 0.05-0.15. In particular, in continuous drawing and ironing can operations, the working temperature rises to about 60 ° C. due to heat generated during molding, and it is assumed that the importance of controlling film properties at 60 ° C. has been demonstrated. The conventional epoxy paint has a glass transition temperature of about 70 to 120 ° C., a pencil hardness of F to 2 H, an elongation of about 10 to 150%, and a dynamic friction coefficient of about 0.3 to 0.5 at 60 ° C. It is.
[0016]
As a resin system capable of controlling such physical properties, a combination of a resin such as a polyester resin, an epoxy resin, an acrylic resin, or a urethane resin and a curing agent such as a resol type phenol resin or an amino resin can be used. In particular, a polyester resin / resole type phenol resin system is particularly suitable for adjusting the characteristics of the film, and as the polyester resin, a modified polyester resin such as epoxy-modified or urethane-modified can be suitably used. With regard to the epoxy resin, it is appropriate to use a part of the epoxy resin for adjusting the hardness of the polyester-based paint from the above characteristics.
[0017]
Furthermore, as for the polyester resin, those having a number average molecular weight of 10,000 to 80,000, particularly 15,000 to 50,000, a hydroxyl value of 1 to 20, particularly 2 to 12 mg KOH / g have a balance between hardness and workability. Suitable for taking.
[0018]
The polyester resin is synthesized by direct esterification or transesterification of an acid component and an alcohol component.
[0019]
Examples of the acid component constituting the hydroxyl group-containing polyester resin include phthalic anhydride, isophthalic acid, terephthalic acid, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, hexahydroisophthalic acid, hexahydroterephthalic acid, succinic acid, fumaric acid, One or more dibasic acids selected from adipic acid, sebacic acid, maleic anhydride, and the like, and lower alkyl esterified products of these acids are mainly used. If necessary, benzoic acid, crotonic acid, pt-butylbenzoic acid A monobasic acid such as an acid, a tribasic or higher polybasic acid such as trimellitic anhydride, methylcyclohexeric carboxylic acid and pyromellitic anhydride are used in combination.
[0020]
Examples of the alcohol component constituting the polyester resin include ethylene glycol, diethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, 2-methyl-1,3-propanediol. , Dihydric alcohols such as 3-methylpentanediol, 1,4-hexanediol, 1,6-hexanediol, 1,4-dimethylolcyclohexane are mainly used, and glycerin, trimethylolethane, A trihydric or higher polyhydric alcohol such as trimethylolpropane and pentaerythritol can be used in combination. These alcohol components can be used alone or in admixture of two or more.
[0021]
When synthesizing the acid component and the alcohol component by a direct esterification method or transesterification method by a conventional method, if the reaction is carried out under the condition that the carboxyl group is excessive with respect to the hydroxyl group, the carboxyl group is mainly contained. If a polyester resin is obtained and the reaction is carried out under conditions where the hydroxyl group is excessive with respect to the carboxyl group, a polyester resin containing mainly a hydroxyl group can be obtained. Furthermore, it is possible to adjust the amount of hydroxyl groups and carboxyl groups in the single resin by adding an acid anhydride to the polyester resin mainly containing the hydroxyl groups. Examples of the acid anhydride to be reacted with the polyester resin mainly containing a hydroxyl group include phthalic anhydride, succinic anhydride, maleic anhydride, hexahydrophthalic anhydride, trimellitic anhydride, and the like.
[0022]
In the above method, the reaction by the direct esterification method or transesterification method can be promoted by pressurizing or depressurizing operation, or by flowing an inert gas. Furthermore, an organometallic catalyst such as di-n-butyltin oxide can be used as an esterification catalyst during the reaction.
[0023]
The hydroxyl group-containing polyester resin may be any of an oil-free polyester resin, an oil-modified alkyd resin, or a modified product of these resins, such as a urethane-modified polyester resin, a urethane-modified alkyd resin, an epoxy-modified polyester resin, and an epoxy-modified alkyd resin. Among them, an oil-free polyester resin is particularly preferable.
[0024]
As the resol type phenol resin, a phenol component and formaldehyde are heated in the presence of a reaction catalyst to cause a condensation reaction by introducing a methylol group, and a part of the methylol group of the methylolated phenol resin is alkylated with alcohol. It is obtained by etherification.
[0025]
In the production of the resol-type phenol resin crosslinking agent, a bifunctional phenol compound, a trifunctional phenol compound, a tetrafunctional or higher functional phenol compound, or the like can be used as the phenol component that is a starting material.
[0026]
Examples of the bifunctional phenol compound used for the production of the resol type phenol resin crosslinking agent include o-cresol, p-cresol, p-tert-butylphenol, p-ethylphenol, 2,3-xylenol, 2,5-xylenol, and the like. The trifunctional phenol compound includes phenol, m-cresol, m-ethylphenol, 3,5-xylenol, m-methoxyphenol, and the like. Examples of the compound include bisphenol A and bisphenol F. These phenol compounds may be used alone or in combination of two or more.
[0027]
Examples of formaldehydes used in the production of the resol type phenol resin include formaldehyde, paraformaldehyde, trioxane, and the like, which can be used alone or in combination of two or more.
[0028]
As the alcohol used for alkyl etherifying a part of the methylol group of the methylolated phenol resin, a monohydric alcohol having 1 to 8 carbon atoms, preferably 1 to 4 carbon atoms, can be suitably used. Suitable monohydric alcohols include methanol, ethanol, n-propanol, n-butanol, isobutanol and the like.
[0029]
The resol type phenolic resin has an average of 0.5 or more, preferably 0.6 to 3.0 alkoxymethyl groups per benzene nucleus from the viewpoint of reactivity with the hydroxyl group-containing polyester resin (A). Things are suitable.
[0030]
In order to adjust the dynamic friction coefficient of the film obtained from the paint for the inner surface of the can, a wax can be suitably used in addition to the resin and the curing agent.
[0031]
Regarding the blending ratio of the polyester resin and the resol type phenol resin, the balance between curability and workability is within the range of polyester resin / resol type phenol resin = 80/20 to 98/2, preferably 90/10 to 97/3. It is suitable from the viewpoint.
[0032]
Examples of the wax to be added include plant waxes, animal waxes, mineral waxes, petroleum waxes, and fatty acid ester waxes. Among these, liquid waxes are preferably used at 60 ° C.
[0033]
By using liquid wax at 60 ° C for the paint used on the inner surface of the can, there is an effect that the continuity of the film and coverage are difficult to be impaired during DI processing, in addition to adjusting the coefficient of dynamic friction. It becomes suitable as. Specific examples of waxes that are liquid at 60 ° C. include plant waxes, animal waxes, mineral waxes, and fatty acid ester waxes.
[0034]
The plant waxes include carnauba wax, cotton wax, and wood wax, the animal waxes include lanolin wax, gay wax, and beeswax. The petroleum waxes include paraffin wax, microcrystalline wax, and petrolatum. Examples of mineral waxes include ozokerite and montan wax.
[0035]
Examples of the fatty acid ester wax include esterified products of fatty acid sucrose ester polyglycerin ether and fatty acid.
[0036]
The amount of the wax added is suitably 0.1 to 10, preferably 1 to 5 parts by weight per 100 parts by weight of the resin in the paint.
[0037]
Can exterior paint
Since the paint for outer surface of the can of the present invention is processed and printed and polished after processing, the paint continuity after processing is not required as much as the paint for inner surface of the can. Therefore, it is suitable that the glass transition temperature of the film obtained therefrom is 50 to 120 ° C., preferably 60 to 100 ° C., and the pencil hardness is H or higher under the test conditions of 60 ° C. It is possible to use a combination of a resin such as a polyester resin, an epoxy resin, an acrylic resin, or a urethane resin and a curing agent such as a resol type phenol resin or an amino resin. The amino resin system is suitable for adjusting the properties of the film without coloring the paint. The resol type phenolic resin, which is a curing agent, tends to turn yellow when the paint film is baked and cured, so care must be taken when using it for paints on the outside of cans. Thus, it is suitable for a usage method of coloring and gold color, a usage method of using in combination with an amino resin by taking advantage of the corrosion resistance of the resol type phenolic resin.
[0038]
As the polyester resin, modified polyester resins such as epoxy-modified and urethane-modified can also be suitably used. It is also effective to use a part of the epoxy resin for improving the hardness and adhesion of the polyester paint.
[0039]
Furthermore, as for the polyester resin, those having a number average molecular weight of 10,000 to 80,000, particularly 15,000 to 50,000, a hydroxyl value of 1 to 20, particularly 2 to 12 mg KOH / g have a balance between hardness and workability. Suitable for taking.
[0040]
As said polyester resin, what was mentioned in description of the coating material for can inner surfaces can be used.
[0041]
Examples of amino resins that are curing agents include methylolated amino resins obtained by reaction of amino components such as melamine, urea, benzoguanamine, acetoguanamine, steroguanamine, spiroguanamine, and dicyandiamide with aldehydes. Examples of the aldehyde include formaldehyde, paraformaldehyde, acetaldehyde, benzaldehyde and the like. In addition, those obtained by etherifying this methylolated melamine resin with one or more alcohols are also included in the amino resin. Examples of the alcohol used for etherification include monohydric alcohols such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, 2-ethylbutanol, and 2-ethylhexanol. . Among these, a melamine resin obtained by etherifying at least a part of a methylol group of a methylol melamine resin with a C1-4 monohydric alcohol is preferable.
[0042]
Specific examples of the melamine resin include Cymel 300, 303, 325, 327, 350, 730, 736, 738 (all of which are manufactured by Mitsui Cytec Co., Ltd.), Melan 522, 523 ( As described above, all are manufactured by Hitachi Chemical Co., Ltd.), Nicarak MS001, MX430, MX650 (all are manufactured by Sanwa Chemical Co., Ltd.), Sumimar M-55, M-100, M-40S (all are manufactured by Sumitomo) Chemical Ether), Resimin 740, 747 (above, both manufactured by Monsanto Co.) and other methyl etherified melamine resins; Uban 20SE, 225 (above, both manufactured by Mitsui Chemicals), Super Becamine J820-60, L-117-60, L-109-65, 47-508-60, L-118-60, G821-60 (above Butyl etherified melamine resins such as Dainippon Ink and Chemicals Co., Ltd .; Cymel 202, 232, 266, XV-514, 1130 (all of which are manufactured by Mitsui Cytec), Nicarax MX45, MX500, Methyl ethers such as MX600, MS35, MS95 (all of which are manufactured by Sanwa Chemical Co., Ltd.), Resimin 753, 755 (all of which are manufactured by Monsanto), Sumimar M-66B (manufactured by Sumitomo Chemical Co., Ltd.) Examples thereof include mixed etherified melamine resins with butyl ether. These melamine resins can be used alone or in combination of two or more.
[0043]
The blending ratio of the polyester resin and the amino resin is preferably in the range of polyester resin / amino resin = 80/20 to 98/2, preferably 90/10 to 97/3, from the viewpoint of balance between curability and workability.
[0044]
In order to prevent damage to the film obtained from the paint for the outer surface of the can, it is effective to add wax in addition to the resin and the curing agent.
[0045]
Examples of the wax to be added include plant waxes, animal waxes, mineral waxes, petroleum waxes, fatty acid ester waxes, and fluorine waxes. Among these, solid waxes are preferably used at 60 ° C. It is done.
[0046]
By using a solid wax at 60 ° C. for the paint used for painting the outer surface of the can, there is an effect that the coating film can be prevented from being damaged without causing wax breakage due to ironing. Specific examples of the wax that is solid at 60 ° C. include polytetrafluoroethylene wax, polyethylene wax, and oxidized polyethylene wax. Further, it is also effective to use a solid wax at 60 ° C. and a liquid wax at 60 ° C. in combination.
[0047]
The amount of the wax added is suitably 0.5 to 30, preferably 1 to 10 parts by weight per 100 parts by weight of the resin in the paint.
[0048]
Moreover, it is preferable to add an epoxy resin to the system of polyester resin and amino resin for the purpose of improving the hardness and adhesion of the outer surface coating. Examples of the epoxy resin include bisphenol-type epoxy resins, novolak-type epoxy resins; modified epoxy resins in which various modifiers are reacted with epoxy groups or hydroxyl groups in these epoxy resins, from the viewpoint of imparting adhesion. Preferably have low molecular weight and low viscosity. Specific examples include Epicoat 828, 834, 1001, and 154 (all of which are manufactured by Yuka Shell Epoxy Co., Ltd.), Araldite AER250, 280, ECN- 1273, EPN-1179 (all above, manufactured by Asahi Kasei Epoxy), Epototo YD-127, YD-134, YDF-170, YDCN-702 (all above, all manufactured by Tohto Kasei) it can.
[0049]
In the system of hydroxyl group-containing polymer polyester resin and melamine resin, the addition amount of the epoxy resin is 0.1 to 20 parts by weight, preferably 1 to 100 parts by weight with respect to 100 parts by weight of the total amount of the hydroxyl group-containing polymer polyester resin and melamine resin. A range of 10 parts by weight is suitable.
[0050]
In order to accelerate the curing reaction, an acid catalyst can be added to the above can inner surface and can outer surface coatings as necessary. Specific examples include acid catalysts such as p-toluenesulfonic acid, dodecylbenzenesulfonic acid, dinonylnaphthalenesulfonic acid, dinonylnaphthalenedisulfonic acid, phosphoric acid, and amine neutralized products of these acids. Among these, the sulfonic acid compound or an amine neutralized product of the sulfonic acid compound is preferable.
[0051]
The compounding amount of the acid catalyst is determined based on the physical properties of the resulting coating film, etc., and the amount of acid (for example, in the case of an amine neutralized product of a sulfonic acid compound, the amount of the remaining sulfonic acid compound from which the amine has been removed. ) Based on 100 parts by weight of the total amount of the base resin and the curing agent, it is preferably within the range of 0.1 to 5 parts by weight, preferably 0.2 to 2 parts by weight.
[0052]
Moreover, a solvent is normally mix | blended with the said can inner surface and can outer surface coating materials from a paintable viewpoint. Further, if necessary, other resins can be blended for the purpose of modifying the coating film. Further, pigments such as coloring pigments, glitter pigments and extender pigments; anti-aggregation agents, leveling agents, anti-foaming agents. Additives for paints such as foaming agents can also be blended.
[0053]
As said solvent, what can melt | dissolve or disperse | distribute each component, such as said resin, a hardening | curing agent, and other resin used as needed, Specifically, For example, toluene, xylene, a high boiling point petroleum system, for example Hydrocarbon solvents such as hydrocarbons, ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, isophorone, ester solvents such as ethyl acetate, butyl acetate, ethylene glycol monoethyl ether acetate, diethylene glycol monoethyl ether acetate, methanol, Examples include alcohol solvents such as ethanol and butanol, and ether alcohol solvents such as ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, and diethylene glycol monobutyl ether. Al may be used alone or in combination of two or more.
[0054]
The above pigments are mainly blended into can exterior coatings to improve the design of cans. For example, titanium white pigments can be used as white coats, or bright pigments such as aluminum pigments and pearl pigments. Is used for the purpose of giving a metallic feeling and luxury.
[0055]
Manufacturing method of painted metal plate
Next, the manufacturing method of the coated metal plate of this invention is demonstrated.
[0056]
The coated metal plate of the present invention is suitable as a coated steel plate for squeezing and ironing cans by painting and baking the above-mentioned paint for the inner surface of the can and the outer surface of the can by a known coating method such as roll coater coating or spray coating on both surfaces of the metal plate. A coated film can be formed. In the case of double-sided coating, it is preferable from the viewpoint of hygienic properties of the inner surface of the can that the outer surface is first coated and dried and then the inner surface is painted and baked.
[0057]
The baking condition of the coating film is usually about 5 seconds to about 30 minutes under the condition that the maximum reached temperature of the metal plate is about 90 to 300 ° C.
[0058]
As the material for the painted metal plate, various surface-treated steel plates, aluminum plates, aluminum alloy plates and the like conventionally used as DI can materials can be suitably used.
[0059]
【Example】
Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. Hereinafter, both “parts” and “%” are based on weight.
[0060]
Synthesis of polyester resin solution
Synthesis example 1
49.8 parts of terephthalic acid, 49.8 parts of isophthalic acid, 34.4 parts of hexahydroterephthalic acid, 28.5 parts of adipic acid, 99.8 parts of neopentyl glycol, 6.8 parts of trimethylolpropane and a polycondensation catalyst The esterification reaction was carried out while charging, heating and stirring and removing the generated water to obtain a resin having a number average molecular weight of 24,000, a hydroxyl value of 10 mgKOH / g, an acid value of 1.0 mgKOH / g, and a Tg point of 60 ° C. . The obtained resin was diluted with a mixed solvent of methyl ethyl ketone / cyclohexanone = 50/50 to obtain a polyester resin solution A-1 having a solid content of 30%.
[0061]
Synthesis example 2
37.7 parts of phthalic acid, 66.4 parts of isophthalic acid, 46.2 parts of hexahydrophthalic acid, 6.7 parts of trimellitic acid, 12.4 parts of ethylene glycol, 78.8 parts of neopentyl glycol, trimethylolpropane 6 .8 parts and a polycondensation catalyst were charged, heated and stirred, and the esterification reaction was carried out while removing the generated water, and the number average molecular weight 15,000, hydroxyl value 5.0 mgKOH / g, acid value 2.0 mgKOH / g A resin having a Tg point of 80 ° C. was obtained. The obtained resin was diluted with a mixed solvent of methyl ethyl ketone / cyclohexanone = 50/50 to obtain a polyester resin solution A-2 having a solid content of 30%.
[0062]
Synthesis Example 3 (for comparative example)
Polyester resin “Byron 103” manufactured by Toyobo Co., Ltd. (number average molecular weight 22,000, hydroxyl value 5 mg KOH / g, acid value 2 mg KOH / g or less, Tg point 45 ° C.) in a mixed solvent of methyl ethyl ketone / cyclohexanone = 50/50 Dilution was performed to obtain a polyester resin solution A-3 having a solid content of 30%.
[0063]
Synthesis Example 4 (for comparative example)
Unitika's polyester resin “Unitika Elitel UE-3300” (number average molecular weight 8,000, hydroxyl value 18 mg KOH / g, acid value 1 mg KOH / g or less, Tg point 45 ° C.) mixed solvent of methyl ethyl ketone / cyclohexanone = 50/50 To obtain a polyester resin solution A-4 having a solid content of 30%.
[0064]
Manufacture of internal and external coatings
Production Examples 1-15
An inner surface paint and an outer surface paint were prepared according to the formulation shown in Table 1 below. In addition, the manufacture examples 10-15 were created for the comparative examples.
[0065]
The formulations in Table 1 are shown in terms of solid weight.
[0066]
[Table 1]

[0067]
Create painted metal sheet
Examples 1-10 and Comparative Examples 1-9
Using the inner surface paint and the outer surface paint obtained in the above production example, each coated metal plate was prepared in the combinations shown in Table 3 below. In this coated metal plate, a 0.28 mm-thick # 3004 aluminum material that has been subjected to phosphoric acid chromate treatment is used. First, the outer surface paint is applied to the bar coater so as to have the dry coating amounts shown in Table 3. After coating and drying at 100 ° C for 60 seconds, paint the inner surface on the opposite side of the material with a bar coater so that the dry coating amount shown in Table 3 is reached, and the maximum material temperature reaches 270 ° C. It was created by baking for 20 seconds under the following conditions.
[0068]
The performance of the coating film obtained from each inner surface coating material and each outer surface coating material and each coated metal plate obtained by the above method were tested according to the following test methods. The test results are shown in Table 3 below.
[0069]
Test method
Tg (° C.): Using a bar coater, paint the inner and outer coatings on the tin plate so that the coating amount after drying is 180 mg / 100 cm 2, under the condition that the maximum material temperature reaches 270 ° C. Baking was performed for 20 seconds. The obtained coated plate is cut into a size of 5 mm × 5 mm, and a TMA curve is measured by a penetration method (load 1 g) using a TMA-4000 device manufactured by MAC SCIENCE, and the intersection of tangents before and after the inflection point is Tg. As evaluated.
[0070]
60 ° C. Elongation: Using a bar coater, paint the inner and outer coatings on the tin plate so that the coating amount after drying is 180 mg / 100 cm 2, under the condition that the maximum material temperature reaches 270 ° C. Baking was performed for 20 seconds. This coating film was peeled off by a mercury amalgam method to obtain a free film. This film was cut to 5 mm width and 30 mm length, and the upper and lower 5 mm was used as the allowance, and the elongation rate until breakage was measured at an elongation rate of 500 mm / min in an atmosphere at 60 ° C. using an autograph AGS-H device manufactured by Shimadzu Corporation. did.
[0071]
Pencil hardness at 60 ° C .: Each coated metal plate is placed on a heating plate set at 60 ° C., and after confirming that the surface of the sample has reached 60 ° C. with a surface thermometer, JIS K-5400 8.4.2. (1990), a pencil scratch test was conducted. Evaluation was performed by the tearing method.
[0072]
60 ° C. dynamic friction coefficient: Toyo Seiki Co., Ltd. FRICTION TESTER TR-2 apparatus heating plate is set to 60 ° C., and each coated metal plate is placed thereon. After confirming that the surface of the sample reached 60 ° C. with a surface thermometer, the dynamic friction coefficient was measured under the conditions of a load of 2 kg and a pulling speed of 1000 mm / min. The smaller the dynamic friction coefficient, the better the lubricity.
[0073]
Pressure adhesiveness at 60 ° C .: Each coated metal plate is cut into a size of 5 cm × 5 cm, and a predetermined paper (Kleenex Facial Tissues manufactured by Crecia) is covered on the coated surface, and then in an atmosphere of 60 ° C. at 30 Kg / cm 2 for 24 hours. After pressurizing, it was taken out and returned to room temperature, and then the paper was peeled off to evaluate the state.
○: Can be peeled off
Δ: Can be removed, but paper fibers remain in the coating film
X: Cannot be peeled off.
[0074]
D & I forming processability: Each coated metal plate was processed by Eriksen's metal thin plate deep drawing tester 142 type, and the five steps shown in the table below were sequentially performed from a blank diameter of 82 mm, and finally the drawing ratio = about 37 %, Ironing ratio = approx. 60%, and then subjected to the drawing ironing process, and the can manufacturing property, appearance, and covering property were evaluated.
[0075]
[Table 2]

[0076]
[Can manufacturing property] Evaluation was carried out according to the following criteria from the rate at which 10 cans were molded.
A: Success rate 100%.
○: Success rate is 90% or more and less than 100%.
Δ: Success rate of 50% or more and less than 90%.
X: Success rate is less than 50%.
[Appearance] With respect to what could be molded, the state of the processed part was visually evaluated, and those in which no abnormality was observed in the coating film were marked as ◯.
[Coating property] To 95 parts of 2N hydrochloric acid solution, 5 parts of copper sulfate was added and dissolved, and 100 parts of acetone was further mixed to prepare a test solution. The can processed into this test solution was immersed for 60 seconds, then washed with water and opened, and the degree of corrosion on the inner surface was visually evaluated.
○: Corrosion is not recognized.
○ △: Partial corrosion is observed in the most ironing part of the upper part of the can.
Δ: Corrosion is observed on almost the entire surface of the ironing portion above the middle portion of the can.
X: There are obvious coating film defects, and large corrosion has occurred.
[0077]
[Table 3]

[0078]
【The invention's effect】
The double-sided coated metal plate of the present invention has moderately high strength and smoothness of the coating film, can sufficiently withstand severe processing such as drawing ironing, and is particularly suitable as a pre-coated steel plate for DI cans. Is.

Claims (7)

It is a double-sided coated metal plate, the dry coating amount of the film that becomes the inner surface of the can after processing is 90 to 400 mg / 100 cm2, the glass transition temperature is 50 to 120 ° C, and the pencil hardness is H or higher under the test conditions of 60 ° C. The film has an elongation of 200 to 600% and a dynamic friction coefficient of 0.03 to 0.25. The dry coating amount of the film that becomes the outer surface of the can after processing is 15 to 150 mg / 100 cm2, and the glass transition temperature is 50. A coated metal plate for a drawn iron can having a pencil hardness of H or higher at a test temperature of ˜120 ° C. and 60 ° C. The paint used for forming the film that becomes the inner surface of the can after processing contains a hydroxyl group-containing polymer polyester resin having a number average molecular weight of 10,000 to 80,000 and a resol type phenol resin, and the outer surface of the can after processing The paint used for forming the coating film on the side contains a hydroxyl group-containing polymer polyester resin having a number average molecular weight of 10,000 to 80,000 and an amino resin and / or a resol type phenol resin. Painted metal plate. The coated metal plate according to claim 1 or 2, wherein the coating used for forming the coating on the outer surface side of the can after the processing further contains an epoxy resin. The coating used to form the coating that becomes the inner surface of the can after processing contains a wax that becomes liquid at 60 ° C., and the coating used to form the coating that becomes the outer surface of the can after processing is solid at 60 ° C. The coated metal plate according to any one of claims 1 to 3, which contains a wax. The liquid wax at 60 ° C. is at least one selected from fatty acid ester wax, lanolin wax, montan wax, microcrystalline wax, and carnauba wax, and the wax that is solid at 60 ° C. is fluorine wax and polyolefin wax. The coated metal plate according to any one of claims 1 to 4, which is at least one selected from the group consisting of: The coated metal sheet according to any one of claims 1 to 5, wherein the coating on the outer surface side of the can after processing contains a glitter pigment. A drawn and ironed can obtained by drawing and ironing the coated metal plate according to any one of claims 1 to 6.