JP2013071328A - Resin coated metal plate for container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin coated metal plate for a container, capable of satisfying a number of properties required for a material of cans for food.SOLUTION: On at least one face of the metal plate, a resin coating layer (A) having a multilayer structure mainly comprising a polyester resin is provided. The resin coating layer (A) is firmly attached to a surface of the metal plate and has a resin layer (a1) which contains components of the following (I) to (IV) and which has a polyester resin as the main component. Preferably, a polyester film (a2) is formed on the resin layer (a1). (I) the polyester resin, (II) one or more selected from the group comprising a polyamine resin, a poly(amidoamine) resin and a polyamide resin, and (III) a conductive polymer, and (IV) a dopant.

Description

  The present invention relates to a resin-coated metal plate for containers used for, for example, can bodies and lids for canned foods.

  Conventionally, metal plates such as tin-free steel (TFS) and aluminum, which are materials for metal cans used for food canning, have been coated for the purpose of improving corrosion resistance, durability, weather resistance, and the like. However, this coating process has a problem that not only the baking process is complicated, but also a long processing time is required and a large amount of solvent is discharged.

  Therefore, in order to solve these problems, instead of the coated steel sheet, a film laminated metal sheet was developed by laminating a thermoplastic resin film on a heated metal sheet, and is currently used industrially as a food canning material. Yes. Above all, the film laminated steel sheet with PET film heat-sealed to the TFS surface has excellent adhesion, workability and corrosion resistance, so it can be applied to most food cans, and further demand expansion is expected in the future. It is.

  In addition, regions where remarkable economic development such as BRICs countries are attracting attention as regions where demand is further expanded, and future increases in demand will be remarkable. In view of such a global market, film laminate metal plate technology is likely to become a global standard, and it is certain that it will become increasingly important.

  Under such circumstances, it has become clear that the film-laminated metal plate needs further performance improvement. It is necessary to greatly improve the corrosion resistance, especially the corrosion resistance of the scratched part. The reason is shown below.

  Since the corrosion resistance of the film laminated metal plate depends on the insulating properties of the film, it is essential to ensure the covering property. However, when a scratch penetrating the film occurs, the insulation of the portion is lost, and the corrosion resistance cannot be ensured. Furthermore, corrosion tends to concentrate on the scratched part, and there is a high possibility of causing local corrosion. If local corrosion progresses remarkably, perforation occurs in the can wall, and the function as a can is lost.

  Until now, film-laminated metal plates have been used mainly in the Japanese domestic market, and have been processed and commercialized into many types of cans. A domestic can manufacturing company has a production line management system and a product quality control system. For example, troubles (for example, roll slipping) that damage the steel plate in the can manufacturing line hardly occur. Therefore, the film-laminated metal plate was hardly damaged so as to penetrate the film, and the film continued to cover the steel plate even after can molding, and excellent corrosion resistance could be maintained. In addition, even if a scratch penetrating the film occurs, a defect inspection is performed on all the cans after making the can, and the damaged can is a system that is not distributed to the market.

  On the other hand, when looking overseas, there are a wide variety of can manufacturing companies and can manufacturing companies, and their technical levels vary. There are many can manufacturing companies that have poor quality control systems compared to domestic can manufacturing companies, and many companies have troubles on the production line. In addition, there are few can manufacturing companies in the world that carry out full-scale inspections of molded cans, and most are only sampling inspections. Accordingly, there is a risk that cans with scratches penetrating the film may pass through the inspection line and be distributed to the market, and film laminated metal cans having poor scratch resistance may cause a large market complaint. Since we cannot expect the same level of production management system and full-scale inspection system as in Japan for can manufacturers around the world, there is no way to improve the corrosion resistance of scratches on film laminated metal plates. Will not be achieved.

In contrast to the above, Patent Documents 1 and 2 are cited as techniques for improving the scratch corrosion resistance, for example.
Patent Document 1 is a technique related to a fluororesin film laminated steel sheet, and utilizes the water repellency of a fluororesin film. According to this, since the water contact angle on the surface is 90 ° or more, all the water adhering to the surface becomes spherical, and the spherical shape is maintained even in the scratched part, so that water enters the damaged part. It is described that corrosion is suppressed without any problems. However, since there is no fluororesin in the scratched part, there is no water repellent effect and no corrosion inhibiting effect can be expected.
Patent Document 2 is a technique related to a laminated type fluororesin film laminated steel sheet, in which a polychlorinated resin film of 100 μm or more is laminated under the fluororesin film. This technique aims to prevent the scratches from reaching the steel sheet surface, and is not a technique for improving so-called scratch corrosion resistance. Moreover, since it is a technique that merely increases the film thickness, the industrial utility value is extremely low.

  In response to these Patent Documents 1 and 2, the inventors form a film that protects against corrosion factors by promoting passivation of the base metal even if the base metal is exposed at the scratch. Inspired by a new concept of ensuring the corrosion resistance of scratches. Unlike conventional resource-consumption sacrificial protection technologies such as galvanization, this concept is a resource-saving protection technology that utilizes the spontaneous passivation reaction of the underlying metal.

  As a technique for promoting the passivation of metals, a technique using a passivating agent such as a transition metal such as molybdenum acid or tungsten acid has been published in patents and papers. However, these are so-called rare metals, which are essential materials for the semiconductor industry, etc., and are likely to fall into an excessive demand situation. In particular, prices have jumped several times since 2002, when the BRICs countries achieved significant economic development, and this trend will continue. Further, regarding the passivating ability, it has been reported in many papers that it is at a level that does not reach the conventional chromate treatment, and does not satisfy the performance requirements of the inventors.

  Furthermore, the inventors paid attention to and examined conductive polymers that have recently been studied for application to metal corrosion protection. A conductive polymer is a polymer in which a π-electron conjugated system has been developed, and polyacetylene, polyaniline, polypyrrole, polythiophene, and the like are known. Of these, polyaniline has been extensively studied for its metal anticorrosive ability. Patent Documents 3 to 5 show application examples to metal plates.

  Patent Document 3 describes that by forming a film made of resin, polyaniline, and inorganic oxide on a metal plate, adhesion and corrosion resistance that can replace the conventional chromate treatment can be obtained. However, a water-soluble or water-dispersible acrylic resin, epoxy resin, urethane resin, or the like is used as the base resin, and these are difficult to apply to the application fields assumed by the inventors. The reasons are as follows: a) Insufficient compatibility between the PET film and the base resin, so that the interlayer adhesion cannot be ensured. B) The mechanical properties of the resin (the balance between the elongation properties and the strength properties) are formed into food cans. The resin is destroyed in the molding process, not at a level that follows the processing. C) Since less than 40% of an inorganic oxide is added as an essential component, the resin is destroyed in the molding process, as in (a). D) When a water-soluble resin is used, the resin is dissolved in a corrosive environment and corrosion resistance cannot be obtained. E) Even when a water-dispersible resin is used, a monomer having a hydrophilic functional group or Copolymerization with a polymer is necessary, and it is difficult to ensure the level of corrosion resistance assumed by the present invention. F) Technology that assumes coating surface treatment, and the technical idea itself is different from the present invention. All It is.

  Patent Document 4 describes that a conductive polymer having an average molecular weight of 20000 or more is contained in an organic resin film and formed on a steel plate. The inadequacies of this technology are: a) the conductive polymer is made high molecular weight, but the skeleton of the molecular chain remains rigid and does not bring about the effect of improving workability; The degree of crystallinity is defined without any upper limit, but it is in the direction of hindering workability, and is not considered at all for application to high processing applications assumed by the present invention. However, since it is not specified because it is not limited to a wide array of general substances, its importance is not found. D) It is a technology that assumes coating surface treatment, and the technical idea itself is different from the present invention. Etc.

  The same applies to Patent Document 5, and the base resin is limited to epoxy-based, urethane-based, and fluorine-based materials. Therefore, it is difficult to apply to the field assumed by the present invention.

Japanese Patent Laid-Open No. 7-256819 Japanese Patent Laid-Open No. 10-264305 JP-A-10-251509 JP 2007-190896 A JP 2006-326459 A

  In view of such circumstances, an object of the present invention is to provide a resin-coated metal sheet for containers that can cope with many characteristics required for food canned materials.

As a result of intensive studies by the present inventors for solving the problems, the following knowledge was obtained.
A resin coating layer having a multilayer structure mainly composed of a polyester resin is provided on at least one surface of the metal plate. And (a) at least one selected from the group consisting of a polyester resin, (b) a polyamine resin, a polyamidoamine resin, and a polyamide resin, (c) a conductive polymer, and (d) a resin layer containing a dopant on a metal plate The resin-coated metal plate for containers having many excellent functions such as excellent workability and scratched corrosion resistance can be obtained by laminating a polyester film on the upper layer.

The present invention has been made based on the above findings, and the gist thereof is as follows.
[1] A resin coating layer (A) having a multilayer structure mainly composed of a polyester resin is provided on at least one surface of a metal plate, and the resin coating layer (A) is in close contact with the metal plate surface as described below. A resin-coated metal sheet for containers, which has a resin layer (a1) containing the components of (i) to (d) and mainly composed of a polyester resin.
(Ii) Polyester resin (b) Any one or more selected from the group consisting of polyamine resin, polyamidoamine resin, polyamide resin (c) Conductive polymer (d) Dopant [2] The resin coating layer (A) is The resin-coated metal sheet for containers according to [1], comprising a resin layer (a1) and a polyester film (a2) formed as an upper layer of the resin layer (a1).
[3] The resin-coated metal plate for containers according to [1] or [2], wherein the resin layer (a1) further contains (e) an epoxy resin.
[4] The container according to any one of [1] to [3], wherein the resin layer (a1) further contains (f) a metal alkoxide compound and / or a metal chelate compound. Resin coated metal plate.
[5] The conductive polymer (c) includes polyaniline, polypyrrole, polythiophene, polyalkylthiophene, polyalkyldioxythiophene, polyisothianaphthene, polyphenylene, polyfuran, polyphenylene vinylene, polyacene, alkylenedioxythiophene, and each of these. In any one of the above [1] to [4], which is one or two or more selected from a polymer derivative and a copolymer of two or more monomers constituting each polymer. The resin-coated metal plate for containers as described.
[6] The above-mentioned [1] to [5], wherein the (d) dopant is added in an amount of 0.01 to 1.00 mol with respect to 1 mol of the monomer that forms the conductive polymer (c). The resin-coated metal plate for containers according to any one of the above.
[7] The resin-coated metal for containers according to any one of [1] to [6], wherein the (a) polyester resin is a polyester resin containing diphenolic acid as an essential component. Board.
[8] The polyester film (a2) is a biaxially stretched polyester film in which 85% by mass or more of the structural units of the polyester resin are ethylene terephthalate units and / or ethylene naphthalate units, and the biaxially stretched polyester film is inorganic. The resin-coated metal sheet for containers according to any one of the above [2] to [7], comprising particles and / or organic particles.

  ADVANTAGE OF THE INVENTION According to this invention, the resin-coated metal plate for containers which can respond | correspond to many characteristics requested | required of the raw material for food cans, and has the outstanding damage part corrosion resistance is obtained. Since it has such characteristics, the resin-coated metal plate for containers of the present invention can be applied not only to the domestic market in Japan but also to all can markets around the world, and is promising as a new resin-coated metal plate for containers. .

It is a figure which shows the principal part of the laminating apparatus of a metal plate. Example 1 It is a figure which shows the cross-section of a film lamination metal plate. Example 1 It is a figure which shows the position of the crosscut damage | wound provided to the can trunk | drum. Example 1 It is a figure which shows the method of measuring the maximum corrosion width from an artificial wound. Example 1

Hereinafter, the resin-coated metal plate for containers of the present invention will be described in detail.
First, the metal plate used by this invention is demonstrated.
As the metal plate of the present invention, an aluminum plate or a mild steel plate widely used as a can material can be used. In particular, a surface-treated steel sheet (hereinafter referred to as TFS) on which a two-layer film is formed, in which the lower layer is made of metallic chromium and the upper layer is made of chromium hydroxide, is optimal.
The amount of adhesion of the metal chromium layer and chromium hydroxide layer of TFS is not particularly limited, but from the viewpoint of adhesion after processing and corrosion resistance, both are in terms of Cr, the metal chromium layer is 70 to 200 mg / m ² , chromium hydroxide layer is preferably in the range of 10 to 30 mg / ^{m 2.}
And the resin-coated metal plate for containers of the present invention has a resin coating layer (A) having a multilayer structure mainly composed of a polyester resin on at least one surface of the metal plate. And this resin coating layer (A) has the resin layer (a1) closely_contact | adhered with the said metal plate surface, Furthermore, the said resin layer (a1) has a polyester resin as a main component and the following (i)-(d). ) Component.
(B) Polyester resin (b) Any one or more selected from the group consisting of polyamine resin, polyamidoamine resin, polyamide resin (c) Conductive polymer (d) dopant Next, a resin layer (a1 in close contact with the metal plate surface ).
(A) Polyester resin The polyester resin preferably has a number average molecular weight of 3000 to 100,000, more preferably 5000 to 30000, and still more preferably 10000 to 25000. The number average molecular weight is a conversion value by comparison with polystyrene in gel permeation chromatography analysis. If the number average molecular weight is lower than 3000, the processability is deteriorated, and if it is higher than 100,000, the viscosity at the time of coating may be increased and appropriate coating may not be performed. In particular, when the number average molecular weight is 10,000 to 25,000, the balance between corrosion resistance and workability is extremely good.
The glass transition temperature of the polyester resin is preferably 0 ° C to 100 ° C, more preferably 10 ° C to 90 ° C, and still more preferably 30 to 80 ° C. When the glass transition temperature is lower than 0 ° C., the barrier property against water vapor, oxygen and the like is inferior, so that the corrosion resistance of the coating film is inferior and the blocking property may be inferior. When the glass transition temperature is higher than 100 ° C., the coating film becomes hard and workability may be deteriorated. Furthermore, the skeleton of the polyester resin is preferably linear rather than branched.

  The polyester resin preferably contains diphenolic acid as an essential component. When the polyester resin contains diphenolic acid as an essential component, the reactivity with the phenolic resin increases and the curing speed increases, resulting in improved water resistance and corrosion resistance. The amount of diphenolic acid introduced into the polyester resin is preferably 0.1 to 10 mass%. If it is lower than 0.1 mass%, the effect of improving the curability, water resistance and corrosion resistance cannot be obtained, and if it exceeds 10 mass%, the curing proceeds excessively and the workability may be inferior.

As polyester resin (I), what made the esterification reaction of a polybasic acid component and a polyhydric alcohol component can be used.
Examples of the polybasic acid component include one or more dibasic acids such as phthalic anhydride, isophthalic acid, terephthalic acid, succinic acid, fumaric acid, adipic acid, azelaic acid, sebacic acid, dimer acid, and the like. Lower alkyl esterified products are used, and monobasic acids such as benzoic acid and crotonic acid, tribasic or higher polybasic acids such as trimellitic anhydride and methylcyclohexytricarboxylic acid are used in combination as necessary.
Polyhydric alcohol components include ethylene glycol, diethylene glycol, propylene glycol, 1,4 butanediol, neopentyl glycol, 3-methylpentanediol, 1,4-hexanediol, 1,6-hexanediol, cyclohexanedimethanol A trihydric or higher polyhydric alcohol such as glycerin, trimethylolethane, trimethylolpropane, or pentaerythritol can be used in combination as needed. These polyhydric alcohols can be used alone or in admixture of two or more.

  Examples of the commercially available polyester resin (A) include Byron 300, 500, 560, 600, 630, 650, 670, Byron GK130, 140, 150, 190, 330, 590, 680, manufactured by Toyobo Co., Ltd. 780, 810, 890, Elitel UE-3220, 3500, 3210, 3215, 3216, 3620, 3240, 3250, 3300 manufactured by Unitika Ltd., Aronmelt PES-310, 318, 334 manufactured by Toagosei Co., Ltd. .

(B) One or more selected from the group consisting of polyamine resins, polyamidoamine resins, and polyamide resins. Polyamine resins, polyamidoamine resins, and polyamide resins have a faster curing speed and form a tough film compared to melamine resins. It is excellent in that it can be done. Compared with resin compositions composed of polyester / melamine, epoxy / melamine, etc., it has excellent curing characteristics, so it can exhibit particularly excellent performance in terms of retort resistance, corrosion resistance, workability, etc. It becomes possible.

  Specific examples of the polyamine resin include diethylenetriamine, triethylenetriamine, and triethylenepentamine as the aliphatic amine, and isophoronediamine as the alicyclic polyamine. In addition, an epoxy resin or acrylonitrile may be added to an aliphatic polyamine or modified by reacting formaldehyde and phenol to improve workability, reduce irritation, or improve mechanical properties. Examples of the aromatic polyamine include metaphenylenediamine, diaminodiphenylsulfonic acid, and diaminodiphenylmethane. Commercially available products include EPICRON EXB-353 manufactured by DIC Corporation, Ancamine 2596 manufactured by Air Products Japan Co., Ltd., Ancamine 2605, and the like.

  The polyamide amine resin and the polyamide resin are compounds synthesized by, for example, a dehydration condensation reaction between fat and fatty acid and polyamine. Commercially available products include Sanyo Kasei Polyamide L-15-3, Polyamide L-45-3, Air Products Japan Co., Ltd. Ancamide 2137, Sunmide 330, Sunmide X-2000, and the like.

(C) Conductive polymer By adding a conductive polymer to the polyester resin layer, passivation of the base metal can be promoted, and scratch corrosion resistance can be imparted to the film laminate metal plate. Since the oxidation-reduction potential of the conductive polymer is noble with respect to the potential of the base metal, an oxidation reaction of the base metal and a reduction reaction of the conductive polymer occur at the interface with the base metal, and a stable passive film at the interface. Form. Since the passive film is an insulator and is dense, it functions as a barrier layer against corrosion factors. Therefore, the corrosion resistance of the base metal can be greatly improved.
Here, it is known that the oxidation-reduction reaction of the conductive polymer is reversible, and returns to the original state by a coupling reaction with the reduction reaction of dissolved oxygen. That is, the conductive polymer can be expected to have an effect of permanently preventing the base metal without deteriorating itself due to its reversible redox property.
Since the above anticorrosion process promotes spontaneous passivation of the base metal in a corrosive environment, it can be considered that the conductive polymer has a kind of self-repair action. Therefore, even if a scratch penetrating the film occurs, it is possible to remarkably suppress the progress of corrosion by forming a passivating film around the wound portion.

  As the conductive polymer used, polyaniline, polypyrrole, polythiophene, polyalkylthiophene, polyisothianaphthene, polyphenylene, polyfuran, polyphenylene vinylene, polyacene, alkylenedioxythiophene and their derivatives, which are π electron conjugated polymers, and Examples thereof include one or a mixture of two or more selected from copolymers of these monomers, and polyethylenedioxythiophene, which is a polymer of alkylenedioxythiophene. Among them, polyaniline, polypyrrole, and polyethylenedioxythiophene have high electrical conductivity and smooth exchange of electrons at the interface with the base metal, and thus have high passivation ability and a large anticorrosion effect.

  The addition amount of the conductive polymer is preferably in the range of 0.1 to 15.0 mass% with respect to the polyester resin layer (a1). If the addition amount is less than 0.1 mass%, the absolute amount of the polymer that contributes to the oxidation-reduction reaction at the interface with the base metal may be insufficient, and the formation of the passivation film at the interface may be insufficient. Since the corrosion resistance of the flaw greatly depends on the ability to form a passivated film, the performance level expected by the inventors cannot be obtained. On the other hand, if the addition amount exceeds 15.0 mass%, the mechanical properties of the conductive polymer affect the physical properties of the entire adhesion layer, and the workability may be greatly deteriorated due to the rigid molecular structure. Therefore, the addition amount of the conductive polymer is preferably in the range of 0.1 to 15.0 mass% with respect to the polyester resin (a1) forming the adhesion layer.

(D) Dopant Since the conductive polymer defined in the present invention is a π-electron conjugated polymer, it is a semiconductor in the undoped state and has a band gap. Therefore, in order to impart conductivity, it is necessary to add a dopant and take π electrons from the conjugated system of the main chain of the conductive polymer to generate holes on the main chain. As holes move on the molecular chains of the polymer, current flows.
Therefore, in order to exhibit the anticorrosion effect expected in the present invention, it is necessary to add a dopant to the polyester resin containing the conductive polymer. As the dopant, one or a mixture of two or more selected from halogens, proton acids, Lewis acids, transition metal halides, and alkali metals is preferable. Of these, halogens, protonic acids, and Lewis acids are particularly suitable because they have a stable anticorrosive ability.
As halogens, bromine, chlorine, iodine and the like can be used, and as the protonic acid, organic carboxylic acids, organic sulfonic acids, organic phosphonic acids, phosphoric acids and polyacids can be suitably used. As the Lewis acid, metal halides such as FeCl ₃ , FeOCl, TiCl ₄ , ZrCl ₄ , SnCl ₄ , MoCl ₅ , WCl ₅ , BF ₄ , BCl ₃ , and PF ₅ can be used.
Among these, proton acids are preferable, and polymer acids such as polystyrene sulfonic acid, polyvinyl sulfonic acid, and polyphosphoric acid are particularly preferable. Since these are capable of forming a film themselves, they increase the continuity of the resin serving as the adhesion layer, and are effective for adhesion and corrosion resistance.

  As addition amount of a dopant, the range of 0.01-1.00 mol is preferable with respect to 1 mol of monomers which form the conductive polymer added in resin. When the amount of the dopant added is less than 0.01 mol with respect to 1 mol of the monomer forming the conductive polymer, the number of carriers generated on the polymer main chain is insufficient, and sufficient electrical conductivity may not be obtained. is there. Since the anticorrosion effect of the conductive polymer depends on the smooth exchange of electrons with the metal to be anticorrosive, the decrease in the conductivity decreases the passivating ability and the scratch corrosion resistance is inferior. On the other hand, if the amount of the dopant added exceeds 1.00 mol% with respect to the conductive polymer, the treatment liquid may become unstable and the processability of the polyester resin layer may be deteriorated, and the corrosion resistance of the scratches may be reduced. Therefore, the addition amount of the dopant is specified in the range of 0.01 to 1.00 mol% with respect to 1 mol of the monomer forming the conductive polymer.

(E) Epoxy resin (preferred conditions)
The epoxy resin mainly improves the adhesion of the film. As a commercially available product of novolak type epoxy resin, Epicron N-665, 670, 673, 680, 690, 695, 730, 740, 770, 865, 870 manufactured by DIC Corporation, manufactured by Dow Chemical Co., Ltd. XD-7855, ECN-1273, 1299 manufactured by Asahi Kasei Epoxy Corporation. Examples of commercially available BPA type epoxy resins include Epicoat 1001 and Epicoat 1004.

(F) Metal alkoxide compounds and / or metal chelate compounds (preferred conditions)
The metal alkoxide-based compound and / or the metal chelate-based compound is any one or more selected from the group consisting of (a) a polyester resin, (b) a polyamine resin, a polyamidoamine resin, and a polyamide resin. Wake up. A crosslinking reaction proceeds between the functional group of each resin and the metal alkoxide compound and / or metal chelate compound. This cross-linking reaction has a significantly faster curing rate compared to the case where there is no metal alkoxide compound and / or metal chelate compound, and as a result, excellent adhesion, workability, Retort resistance and corrosion resistance can be expressed. For example, existing laminated cans are baked at 180 ° C. or higher for several seconds to several minutes after laminating the film, and then the post-heating is used to cure the resin film to ensure the above various required performances. . However, in the present invention, the resin layer containing a metal alkoxide compound and / or a metal chelate compound is sufficiently cured by only heating for a short time of about 1 second when performing heat fusion lamination. The performance equal to or better than that after post-heating can be obtained. Therefore, the post-heating step in the manufacturing process is not necessary, and the manufacturing efficiency is greatly improved. In addition, carbon dioxide emissions can be reduced, which can be a very useful technique in practice. Furthermore, by incorporating a metal into the film, the strength of the film is improved, and as a result, impact resistance and corrosion resistance are greatly improved. For the reasons described above, the resin layer (a1) preferably further contains a metal alkoxide compound and / or a metal chelate compound.
Examples of the metal alkoxide compound and / or metal chelate compound include alkoxide metal compounds such as aluminum, titanium, tin, and zirconium, and metal chelate compounds in which acetoacetic acid is coordinated to the metal.

Composition of resin layer (a1) (mass%)
The ratio (mass) of one or more selected from the group consisting of (A) polyester resin and (B) polyamine resin, polyamidoamine resin, and polyamide resin of the resin layer (a1) of the present invention is 60:40 to 99: 1 is preferable, and 80:20 to 99: 1 is more preferable. When the ratio of the polyester resin is lower than 60, the elongation of the resin layer is insufficient, so that the workability is deteriorated. When the ratio is higher than 99, the curability is insufficient and the water resistance may be inferior.
(Iii) The blending ratio of the conductive polymer is preferably 0.1 to 15.0 mass%, more preferably 1 to 10.0 mass% in the total solid content. When the blending ratio of the conductive polymer is lower than 0.1 mass%, the formation of the passivated film at the interface with the base metal may be insufficient. On the other hand, if it is higher than 15.0 mass%, the adhesion and workability with the base metal may be inferior.
(E) The blending ratio of the epoxy resin is preferably 0.1 to 30 mass% in the total solid content. If the ratio of the epoxy resin is lower than 0.1 mass%, the adhesiveness of the resin layer becomes inferior, and if it exceeds 30 mass%, the water resistance may be inferior.
(F) The blending ratio of the metal alkoxide compound and / or metal chelate compound preferably contains 0.01 to 10 mass% in the total solid content. If the ratio of the metal alkoxide compound and / or the metal chelate compound is lower than 0.01 mass%, the effect of impact resistance and corrosion resistance cannot be obtained, and if it exceeds 10 mass%, the coating film becomes hard and the workability is inferior. In addition, problems such as thickening or gelation of the paint may occur.

Adhesion Amount of Resin Layer (a1) The adhesion amount of the resin layer (a1) is preferably specified in the range of 0.1 g / m ² or more and 5.0 / m ² or less. If it is less than 0.1 g / m ² , the surface of the metal plate cannot be uniformly coated, and the film thickness may be non-uniform. On the other hand, if it exceeds 5.0 g / m ² , the cohesive strength of the resin becomes insufficient, and the strength of the resin layer may be reduced. As a result, at the time of can manufacturing, the resin layer is agglomerated and broken to peel off the film, and the can body portion is torn from that point.
Accordingly, the adhesion amount is preferably 0.1 g / m ² or more and 5.0 g / m ² or less, more preferably 0.1 g / m ² or more and 3.0 g / m ² or less.

Colorant Further, by adding a colorant such as a dye or pigment to the resin layer (a1), the underlying metal plate can be concealed and various colors unique to the resin can be imparted. For example, by adding carbon black as a black pigment, it is possible to conceal the metal color of the base and to impart a high-class feeling of black to food cans.
The particle size of the carbon black can be in the range of 5 to 50 nm, but the range of 5 to 30 nm is suitable in consideration of dispersibility and color developability in the polyester resin.
In addition to the black pigment, by adding a white pigment, the metallic luster of the base can be concealed, the printed surface can be sharpened, and a good appearance can be obtained. As a pigment to be added, it is necessary that an excellent design property can be exhibited after container molding. From such a viewpoint, inorganic pigments such as titanium dioxide can be used. Since the coloring power is strong and rich in spreadability, it is preferable because a good design property can be secured even after container molding.
When a bright color is desired on the surface of the container, it is preferable to use a yellow organic pigment. Although it is excellent in transparency, it has a strong coloring power and a high spreadability, so that a bright appearance can be obtained even after the container is molded. Examples of organic pigments that can be used in the present invention include a color index (CI registered name) of Pigment Yellow 12, 13, 14, 16, 17, 55, 81, 83, 139, 180, 181, At least one of 183, 191 and 214 can be mentioned. In particular, from the viewpoints of vividness of color tone (bright color), heat resistant water discoloration and the like, C.I. I. Pigment Yellow 180 and 214 are more preferably used.
In addition, C.I. I. Pigment red 101, 177, 179, 187, 220, 254, C.I. I. Pigment Blue 15, 15: 1, 15: 2, 15: 3, C.I. I. Pigment Violet 19 and C.I. I. Pigment Orange 64, C.I. I. And CI Pigment Green 7.
The blending ratio of the above colorants preferably contains 0.1 to 70 mass% in the total solid content of the resin layer constituting the resin layer (a1).

A curing catalyst that promotes crosslinking can be added to the curing catalyst resin layer (a1) in addition to the components (A) to (F) and the colorant. For example, inorganic acids such as phosphoric acid, organic acids such as dodecylbenzenesulfonic acid and toluenesulfonic acid, and those blocked with an amine or the like can be used. The blending ratio of the curing catalyst is preferably 0.01 to 5 mass% in the total solid content of the resin layer constituting the resin layer (a1).
Further, conventionally known lubricants, antifoaming agents, leveling agents, pigments, anti-blocking agents such as silica and the like can be added to the resin layer (a1). In addition, other curing agents such as a melamine resin, a benzoguanamine resin, and an isocyanate resin may be used in combination as a curing auxiliary agent, and these can be used in combination with an appropriate one depending on the drying conditions and lamination conditions of the film.

Next, the resin layer (polyester film) (a2) formed on the upper layer of the resin layer (a1) will be described.
In the resin coating layer (A), it is preferable to form a resin layer (a2) containing a polyester resin as a main component on the upper layer of the resin layer (a1) as the uppermost layer, more preferably polyester as the resin layer (a2). It is a film (a2).
Polyester film (a2) composition The polyester film used in the present invention contains ethylene terephthalate and / or ethylene naphthalate in terms of improving the taste characteristics after retort and suppressing the generation of abrasion powder in the can making process. It is desirable to make it the main component. The polyester having ethylene terephthalate and / or ethylene naphthalate as a main constituent is a polyester in which 85 mass% or more of the polyester has ethylene terephthalate and / or ethylene naphthalate as a constituent. More preferably, it is 90 mass% or more because the taste characteristics are good even if the beverage is filled for a long time in a metal can.
On the other hand, other dicarboxylic acid components and glycol components may be copolymerized as long as the taste characteristics are not impaired. Examples of the dicarboxylic acid component include aromatics such as diphenylcarboxylic acid, 5-sodium sulfoisophthalic acid, and phthalic acid. Dicarboxylic acid, oxalic acid, succinic acid, adipic acid, sebacic acid, dimer acid, maleic acid, fumaric acid and other aliphatic dicarboxylic acids, cyclohexanedicarboxylic acid and other alicyclic dicarboxylic acids, p-oxybenzoic acid and other oxycarboxylics An acid etc. can be mentioned.
Examples of the glycol component include aliphatic glycols such as ethylene glycol, propanediol, butanediol, pentanediol, hexanediol, and neopentylglycol, alicyclic glycols such as cyclohexanedimethanol, and aromatics such as bisphenol A and bisphenol S. Examples include glycol, diethylene glycol, and polyethylene glycol. These dicarboxylic acid components and glycol components may be used in combination of two or more.
Moreover, as long as the effect of this invention is not inhibited, you may copolymerize polyfunctional compounds, such as trimellitic acid, trimesic acid, a trimethylol propane.

Particles The polyester film used in the present invention can contain inorganic particles and / or organic particles. The particles in the polyester film used in the present invention are not particularly limited in terms of composition regardless of organic or inorganic, but in terms of protrusion shape, wear resistance, workability, and taste characteristics when formed into a film Therefore, the average particle diameter in terms of volume is preferably 0.005 to 5.0 μm, particularly preferably 0.01 to 3.0 μm. Further, from the viewpoint of wear resistance and the like, the relative standard deviation represented by the following formula is preferably 0.5 or less, and more preferably 0.3 or less.

The major axis / minor axis ratio of the particles is preferably 1.0 to 1.2. The Mohs hardness is preferably less than 7 from the viewpoints of protrusion hardness, wear resistance, and the like.
Moreover, in order to fully express these effects, it is preferable to contain 0.005-10 mass% of particles composed of the above.

Specifically, examples of the inorganic particles include wet and dry silica, colloidal silica, aluminum silicate, titanium oxide, calcium carbonate, calcium phosphate, barium sulfate, alumina, mica, kaolin, and clay. Among them, those in which the functional group on the particle surface reacts with the polyester to produce a carboxylic acid metal salt are preferable. Specifically, those having a functional group of 10 ⁻⁵ mol or more with respect to 1 g of the particles It is preferable in terms of affinity, abrasion resistance, etc., and more preferably 2 × 10 ⁻⁵ mol or more.
As the organic particles, various organic polymer particles can be used. As the type, particles having any composition may be used as long as at least a part thereof is insoluble in the polyester. Moreover, various materials such as polyimide, polyamideimide, polymethyl methacrylate, formaldehyde resin, phenol resin, cross-linked polystyrene, and silicone resin can be used as the material for such particles. Among these, vinyl-based crosslinked polymer particles that have high heat resistance and can easily obtain particles having a uniform particle size distribution are particularly preferable.
Such inorganic particles and organic polymer particles may be used alone, but preferably used in combination of two or more, and further function by combining particles having different physical properties such as particle size distribution and particle strength. A highly functional polyester resin can be obtained.

  In addition, other particles such as various amorphous externally added particles and internally precipitated particles, or various surface treatment agents may be used as long as the effects of the present invention are not hindered. Furthermore, it is preferable from a viewpoint of heat resistance and a taste characteristic that a polyester film is a biaxially stretched polyester film. The biaxial stretching method may be simultaneous biaxial stretching or sequential biaxial stretching, but the stretching conditions and heat treatment conditions are specified, and the refractive index in the thickness direction of the film is 1.50 or more. Is preferable in terms of improving the laminating property and moldability. Furthermore, when the refractive index in the thickness direction is 1.51 or more, particularly 1.52 or more, the plane orientation coefficient is within a specific range in order to achieve both formability and impact resistance even if there is some variation during lamination. This is preferable because it can be controlled.

  In addition, the biaxially stretched polyester film has a structure by solid high-resolution NMR in terms of workability and impact resistance when the neck portion is processed after receiving a thermal history of about 200 to 230 ° C. after drawing in the can making process. The relaxation time of the carbonyl moiety in the analysis is preferably 270 msec or more. More preferably, it is 280 msec or more, Most preferably, it is 300 msec or more. As long as the effects of the present invention are not hindered, other particles, for example, various externally added externally added particles, internally precipitated particles, or various surface treatment agents may be used.

Thickness of the polyester film (a2) The thickness of the polyester film used in the present invention is preferably 5 to 100 μm. When the thickness of the polyester film is less than 5 μm, the covering property is insufficient and the impact resistance and the moldability cannot be ensured. On the other hand, if it exceeds 100 μm, not only the above-mentioned characteristics are saturated and no improvement effect can be obtained, but also the thermal energy required at the time of heat fusion to the metal surface increases, so that the economic efficiency is impaired. From such a viewpoint, the thickness of the more preferable polyester film is 8-50 micrometers, More preferably, it is 10-25 micrometers.

Subsequently, the manufacturing method of the resin-coated metal plate for containers of the present invention will be described.
As an example of a method for forming the resin layer (a1) containing polyester as a main component, a method for forming the polyester resin layer (a1) on the surface of the polyester film (a2) will be described.
A polyester resin as a main component is dissolved in an organic solvent, and an additive component and an optional additive component of the resin layer (a1) defined by the present invention are dissolved or dispersed in an organic solvent to prepare a coating liquid. The coating liquid is applied to the film surface and dried at the time of film formation or after film formation of the polyester film (a2), thereby forming the resin layer (a1).
Examples of the organic solvent for dissolving the polyester resin include aromatic hydrocarbon solvents such as toluene and xylene, ketone solvents such as methyl ethyl ketone and cyclohexanone, and ester solvents such as ethyl acetate and ethylene glycol monoethyl ether acetate. One or more of these can be selected and used as appropriate.
Conventionally known lubricants, antifoaming agents, leveling agents, pigments, anti-blocking agents such as silica, and the like can be added to the coating solution. In addition, other curing agents such as a melamine resin, a benzoguanamine resin, and an isocyanate resin may be used in combination as a curing auxiliary agent, and these can be used in combination with an appropriate one depending on the drying conditions and lamination conditions of the film.
In addition, additives such as a carbon black and an azo pigment as a crosslinking agent, a curing catalyst, and a colorant specified in the present invention can be used by dispersing in an organic solvent. In this case, it is preferable to use a dispersant in combination because the uniformity of the additive can be imparted.
As a method for applying the coating liquid to the polyester film, known coating means such as a roll coater method, a die coater method, a gravure method, a gravure offset method, and a spray coating method can be applied, but a gravure roll coating method is most preferable. . As drying conditions after application of the coating liquid, 80 ° C. to 170 ° C. for 1 to 30 seconds, particularly 100 ° C. to 130 ° C. for 5 to 30 seconds is preferable. The adhesion amount of the resin layer (a1) after drying is preferably in the range of 0.1 to 5.0 g / m ² . If it is in the range of 0.1 to 5.0 g / m ² , it is excellent in continuous uniform coating properties, has no design problems, can secure retort resistance and adhesion, and eliminates blocking properties during film winding. Is done. When the amount is less than 0.1 g / m ² , it is easy to cause difficulty in the continuity of the film, and it may be difficult to express physical properties and design properties. Moreover, the barrier property with respect to water vapor | steam is inferior in a retort sterilization process, a water | moisture content tends to stay in the interface of a resin layer (a1) / polyester film (a2), and may cause retort whitening. On the other hand, if it exceeds 5.0 g / m ² , the solvent releasability after coating is lowered, workability is remarkably lowered, and the problem of residual solvent is likely to occur, so that the blocking property at the time of film winding is remarkably lowered. There is a case. A preferred range is from 0.5 to 2.5 g / m ² .

A method of laminating the polyester film (a2) after coating the resin layer (a1) on the surface of the metal plate The polyester film (a2) coated with the resin layer (a1) is adhered to the surface of the metal plate. Laminate on the surface of the metal plate. For example, a metal plate is heated at a temperature exceeding the melting point of the film, and a polyester film (a2) coated with a resin layer (a1) on the surface is brought into contact with a pressure roll (hereinafter referred to as a laminate roll) and heat-sealed. Can be used. At this time, as described above, it is necessary that the polyester film surface coated with the resin layer (a1) is brought into contact with the metal plate using a laminating roll and thermally fused.
The laminating conditions are appropriately set so that the resin layer defined in the present invention can be obtained. For example, it is preferable that the temperature at the start of lamination is at least equal to or higher than the melting point of the film, and the temperature history received by the film at the time of lamination is in the range of 1 to 35 msec. In order to achieve such lamination conditions, in addition to high-speed lamination, cooling during fusion is also necessary. The pressure applied at the time of lamination is not particularly specified, but the surface pressure is preferably 9.8 to 294 N / cm ² (1 to 30 kgf / cm ² ). If this value is too low, even if the temperature reached by the resin interface is equal to or higher than the melting point, the time is short, so that the melting is insufficient and it is difficult to obtain sufficient adhesion. In addition, if the pressure is large, there is no problem in the performance of the laminated metal plate, but the force applied to the laminate roll is large and equipment strength is required, resulting in an increase in the size of the apparatus, which is uneconomical.

Examples of the present invention will be described below.
Production of metal plate A chrome-plated steel plate was used as the metal plate. A steel plate having a thickness of 0.18 mm and a width of 977 mm subjected to cold rolling, annealing, and temper rolling was subjected to chrome plating treatment after degreasing and pickling to produce a chromium plated steel plate. The chromium plating treatment was performed by chromium plating in a chromium plating bath containing CrO ₃ , F ⁻ , SO ₄ ²⁻ , intermediate rinsing, and electrolysis with a chemical conversion treatment solution containing CrO ₃ and F ⁻ . At this time, electrolysis conditions adjusted to metallic chromium adhering amount and chromium hydroxide deposition amount (current density, the quantity of electricity, etc.), respectively Cr terms was adjusted to ^{120mg / m 2, 15mg / m} 2.

Production of resin coating film on inner surface of can The polyester resin obtained by polymerizing the acid component and glycol component shown in Table 2 at the ratio shown in Table 2 is blended with the particles shown in Table 2 to obtain a resin composition. The product was dried, melted and extruded according to a conventional method, cooled and solidified on a cooling drum to obtain an unstretched film, and then biaxially stretched and heat-set to obtain a biaxially oriented polyester film (a2).
Next, each polyester resin, polyamine resin, polyamidoamine resin, and polyamide resin shown in Table 1, at least one of conductive polymer, dopant, epoxy resin, metal alkoxide compound, and / or metal chelate compound are shown in Table 1. The coating solution was prepared by dissolving in a mixed solvent of toluene and methyl ethyl ketone at a ratio.

  Here, the synthesis example of the polyester resin (I-1) which uses diphenolic acid as an essential component is shown. As the acid component, 50 parts by mass of terephthalic acid, 112 parts by mass of isophthalic acid, 4.9 parts by mass of diphenolic acid, and 50 parts by mass of 2-ethyl-2-butyl-1,3-butanediol as the polyhydric alcohol component, , 99 parts by mass of 4-butanediol, 48 parts by mass of 1,4-cyclohexanedimethanol and 0.07 parts by mass of titanium tetrabutoxide were charged into a 2 L flask, gradually heated to 220 ° C. over 4 hours, and water was retained. Esterification was carried out. After distilling a predetermined amount of water, the polymerization was carried out under reduced pressure to 10 mmHg over 30 minutes, the temperature was raised to 250 ° C., and the latter polymerization was carried out at 1 mmHg or less for 50 minutes. Next, the polymerization under reduced pressure was stopped, the mixture was cooled to 220 ° C. under a nitrogen stream, 1.9 parts by mass of trimellitic anhydride was added, and the mixture was stirred at 220 ° C. for 30 minutes to perform carboxy group modification (post-addition), and then resin The polyester resin (ii) having a number average molecular weight of 22,000, an acid value of 5 (mgKOH / g) and a glass transition temperature of 30 ° C. was obtained. Thereafter, the mixture was cooled to 60 ° C. or lower and diluted with a mixed solution of methyl ethyl ketone / toluene = 50/50 to obtain a polyester resin (I-1) solution having a nonvolatile content of 40%.

  As for the polyester resin (I-2), for example, Byron GK-360 (number average molecular weight: 16000, glass transition temperature: 56 ° C., manufactured by Toyobo), which is a commercially available polyester resin, can be used. Byron GK-360 was mixed in a mixed solvent of cyclohexane / solvesso 150 = 50/50 to obtain a polyester resin (I-2) solution having a nonvolatile content of 40%.

As the polyamine resin, commercially available EPICRON EXB-353 (manufactured by DIC Corporation) was used. A commercially available SUNMIDE 328A (manufactured by Air Products Japan) was used as the polyamide amine resin. As the polyamide resin, commercially available polyamide L-15-3 (manufactured by Sanyo Kasei) was used.
As the conductive polymer, polyaniline (6% toluene solution, manufactured by Nippon Carrit Co., Ltd.) was used, and as the dopant, dodecylbenzenesulfonic acid (TA Chemical Co., Ltd.) was used.
As the epoxy resin, commercially available Epicron N-660 (cresol novolac type epoxy resin, 50% methyl ethyl ketone solution, manufactured by DIC Corporation) was used.
Commercially available TC-200 (titanium octylene glycol chelate, Matsumoto Fine Chemical Co., Ltd.) is used as the metal chelate compound, and commercially available ZA-65 (zirconium butoxide, Matsumoto Fine Chemical Co., Ltd.) is used as the metal alkoxide compound (e). )) Was used.
The coating liquid is applied and dried on one surface of the biaxially oriented polyester film (a2) obtained above with a gravure roll coater so as to have a predetermined dry film thickness, and the resin layer (a1) after drying The film thickness was adjusted. The drying temperature was in the range of 80 to 120 ° C.

Production of film for coating resin on outer surface of can The polyester resin obtained by polymerizing the acid component and glycol component shown in Table 4 in the ratio shown in Table 4 is blended with the particles shown in Table 4 to obtain a resin composition. The product was dried, melted and extruded according to a conventional method, cooled and solidified on a cooling drum to obtain an unstretched film, and then biaxially stretched and heat-set to obtain a biaxially oriented polyester film (a2).
Next, Table 3 shows the polyester resin, polyamine resin, polyamidoamine resin, and polyamide resin shown in Table 3, at least one of conductive polymer, dopant, epoxy resin, metal alkoxide compound, and / or metal chelate compound. The coating solution was prepared by dissolving and dissolving in a mixed solvent of toluene and methyl ethyl ketone at a ratio.
Here, the synthesis example of the polyester resin (I-1) which uses diphenolic acid as an essential component is shown. As the acid component, 50 parts by mass of terephthalic acid, 112 parts by mass of isophthalic acid, 4.9 parts by mass of diphenolic acid, and 50 parts by mass of 2-ethyl-2-butyl-1,3-butanediol as the polyhydric alcohol component, , 99 parts by mass of 4-butanediol, 48 parts by mass of 1,4-cyclohexanedimethanol and 0.07 parts by mass of titanium tetrabutoxide were charged into a 2 L flask, gradually heated to 220 ° C. over 4 hours, and water was retained. Esterification was carried out. After distilling a predetermined amount of water, the polymerization was carried out under reduced pressure to 10 mmHg over 30 minutes, the temperature was raised to 250 ° C., and the latter polymerization was carried out at 1 mmHg or less for 50 minutes. Next, the polymerization under reduced pressure was stopped, the mixture was cooled to 220 ° C. under a nitrogen stream, 1.9 parts by mass of trimellitic anhydride was added, and the mixture was stirred at 220 ° C. for 30 minutes to perform carboxy group modification (post-addition), and then resin The polyester resin (ii) having a number average molecular weight of 22,000, an acid value of 5 (mgKOH / g) and a glass transition temperature of 30 ° C. was obtained. Then, it cooled to 60 degrees C or less, and diluted with the mixed solution of methyl ethyl ketone / toluene = 50/50, and obtained the polyester resin (I-1) solution of 40% of non volatile matters.

  As for the polyester resin (ii-2), for example, commercially available polyester resin Byron GK-360 (number average molecular weight: 16000, glass transition temperature: 56 ° C., manufactured by Toyobo Co., Ltd.) can be used. Byron GK-360 was mixed in a mixed solvent of cyclohexane / solvesso 150 = 50/50 to obtain a polyester resin (I-2) solution having a nonvolatile content of 40%.

As the polyamine resin, commercially available EPICRON EXB-353 (manufactured by DIC Corporation) was used. A commercially available SUNMIDE 328A (manufactured by Air Products Japan) was used as the polyamide amine resin. As the polyamide resin, commercially available polyamide L-15-3 (manufactured by Sanyo Kasei) was used.
As the conductive polymer, polyaniline (6% toluene solution, manufactured by Nippon Carrit Co., Ltd.) was used, and as the dopant, dodecylbenzenesulfonic acid (TA Chemical Co., Ltd.) was used.
As the epoxy resin, commercially available Epicron N-660 (cresol novolac type epoxy resin, 50% methyl ethyl ketone solution, manufactured by DIC Corporation) was used.
Commercially available TC-200 (titanium octylene glycol chelate, Matsumoto Fine Chemical Co., Ltd.) is used as the metal chelate compound, and commercially available ZA-65 (zirconium butoxide, Matsumoto Fine Chemical Co., Ltd.) is used as the metal alkoxide compound (e). )) Was used.

  The coating liquid is applied and dried on one surface of the biaxially oriented polyester film (a2) obtained above with a gravure roll coater so as to have a predetermined dry film thickness, and the resin layer (a1) after drying The film thickness was adjusted. The drying temperature was in the range of 80 to 120 ° C.

Production of Resin-Coated Metal Plate for Container Using a metal band laminating apparatus shown in FIG. 1, the chrome-plated steel sheet 1 obtained above is heated with a metal band heating apparatus 2, and one of the chrome-plated steel sheets 1 is formed with a laminating roll 3. The resin coating layer (A) on the inner surface side of the can was laminated (heat fusion) on the surface, and the resin coating layer (A) on the outer surface side of the can was laminated (heat fusion) on the other surface. Thereafter, the metal band cooling device 5 was used for water cooling to produce a polyester resin-coated metal plate. The laminating roll 3 was an internal water-cooling type, and cooling water was forcibly circulated during the lamination to cool the film during bonding. When laminating the resin film on the metal plate, the time during which the film temperature at the interface in contact with the metal plate was equal to or higher than the melting point of the film was set in the range of 1 to 35 msec.
FIG. 2 shows the coating cross-sectional structure on one side of the resin-coated metal plate for containers (Example of the present invention) manufactured as described above.

Evaluation of Resin-Coated Metal Sheet for Container The characteristics of the resin-coated metal sheet for containers manufactured as described above were measured and evaluated by the following methods (1) to (7), respectively.
(1) After applying wax to a resin-coated metal plate for formable containers, a disc having a diameter of 200 mm was punched out to obtain a shallow drawn can with a drawing ratio of 2.00. Next, the drawn can was redrawn at a drawing ratio of 2.50. Then, after performing doming forming according to a conventional method, trimming was performed, and then neck-in-flange processing was performed to form a deep drawn can. Focusing on the neck-in portion of the deep-drawn can thus obtained, the degree of film damage was visually observed. The evaluation target is the inner and outer surfaces of the can.
(About the score)
◎: No damage or whitening is observed in the film after molding ○: No damage is observed in the film after molding, but partial whitening is observed ×: Can is broken and cannot be molded (2) Molding Back adhesion 1
Cans that were moldable (greater than or equal to) in the moldability evaluation of (1) above were targeted. A sample for peel test (width 15 mm, length 120 mm) was cut out from the can body. Part of the film is peeled off from the long side end of the cut sample. The peeled film is opened in the direction opposite to the peeled direction (angle: 180 °), and using a tensile tester, a tensile speed of 30 mm / min. A peel test was conducted to evaluate the adhesion per 15 mm width. The evaluation object is the can body part on the outer surface of the can.
(Score)
A: 10.0 (N) / 15 (mm) or more B: 5.0 (N) / 15 (mm) or more, less than 10.0 (N) / 15 (mm) x: 5.0 (N) / Less than 15 (mm)
(3) Adhesion after molding 2
Cans that were moldable (greater than or equal to) in the moldability evaluation of (1) above were targeted. After filling the inside of the can with tap water, the lid was wrapped and sealed. Subsequently, retort sterilization was performed at 130 ° C. for 90 minutes, and a peel test sample (width 15 mm, length 120 mm) was cut out from the can body. Part of the film is peeled off from the long side end of the cut sample. The peeled film is opened in the direction opposite to the peeled direction (angle: 180 °), and using a tensile tester, a tensile speed of 30 mm / min. A peel test was conducted to evaluate the adhesion per 15 mm width. The evaluation object is the can body part on the inner surface of the can.
(Score)
A: 10.0 (N) / 15 (mm) or more B: 5.0 (N) / 15 (mm) or more, less than 10.0 (N) / 15 (mm) x: 5.0 (N) / Less than 15 (mm) (4) Scratch corrosion resistance evaluation 1
Cans that were moldable (greater than or equal to) in the moldability evaluation of (1) above were targeted. As shown in FIG. 3, crosscut scratches reaching the base steel plate were made at two locations on the can body on the outer surface of the can. Then, the salt spray test based on JISZ2371 was performed with respect to the can which gave the crosscut damage | wound for 500 hours, and the one-side maximum corrosion width from a damage | wound part was measured. The measurement method is shown in FIG. The evaluation object is the can body part on the outer surface of the can.
(About the score)
◎: One side maximum corrosion width less than 0.5 mm ○: One side maximum corrosion width 0.5 mm to less than 1.0 mm ×: One side maximum corrosion width 1.0 mm or more (5) Scratch corrosion resistance evaluation 2
Cans that were moldable (greater than or equal to) in the moldability evaluation of (1) above were targeted. As shown in FIG. 3, crosscut scratches reaching the base steel plate were made at two locations on the can body on the inner surface of the can. Subsequently, the inside of the can was filled with a 1.5% NaCl + 1.5% sodium citrate mixed solution, and the lid was then wrapped and sealed. Subsequently, the retort sterilization treatment was performed at 130 ° C. for 90 minutes, and then aged for 40 days in a thermostatic bath at a temperature of 50 ° C. Thereafter, the can was opened, and the one-side maximum corrosion width from the cross-cut wound was measured. The measurement method is the same as (4) Scratch corrosion resistance evaluation 1. Moreover, an evaluation object is a can body part on the inner surface of the can.
(About the score)
◎: One-side maximum corrosion width less than 1.0 mm ○: One-side maximum corrosion width of 1.0 mm to less than 3.0 mm x: One-side maximum corrosion width of 3.0 mm or more Tables 5 and 6 show the results obtained as described above.

  From Tables 5 and 6, it can be seen that the examples of the present invention have good performance in terms of moldability, post-mold adhesion, and scratch corrosion resistance required for food canned materials. On the other hand, the comparative example outside the scope of the present invention is inferior in any of the characteristics.

  As a food canned material, it can be used in all markets around the world, mainly for canned food cans and lids.

1 Metal plate (chrome plated steel plate)
2 Metal Band Heating Device 3 Laminate Roll 4a, 4b Film 5 Metal Band Cooling Device

Claims (8)

At least one surface of the metal plate has a resin coating layer (A) having a multilayer structure mainly composed of a polyester resin, and the resin coating layer (A) is in close contact with the metal plate surface and includes the following (i) to ( A resin-coated metal sheet for containers, comprising a resin layer (a1) containing the component d) and containing a polyester resin as a main component.
(B) Polyester resin (b) Any one or more selected from the group consisting of polyamine resin, polyamidoamine resin, and polyamide resin (c) Conductive polymer (d) Dopant   The resin for containers according to claim 1, wherein the resin coating layer (A) comprises the resin layer (a1) and a polyester film (a2) formed on the resin layer (a1). Coated metal plate.   The resin-coated metal sheet for containers according to claim 1 or 2, wherein the resin layer (a1) further contains (e) an epoxy resin.   The resin-coated metal plate for containers according to any one of claims 1 to 3, wherein the resin layer (a1) further contains (f) a metal alkoxide compound and / or a metal chelate compound.   The (c) conductive polymer is polyaniline, polypyrrole, polythiophene, polyalkylthiophene, polyalkyldioxythiophene, polyisothianaphthene, polyphenylene, polyfuran, polyphenylene vinylene, polyacene, alkylenedioxythiophene, and derivatives of these polymers. And a resin coating for containers according to any one of claims 1 to 4, which is one type or two or more types selected from two or more types of copolymers of monomers constituting each of these polymers. Metal plate.   The amount of the (d) dopant added is 0.01 to 1.00 mol with respect to 1 mol of the monomer that forms the conductive polymer (c). The resin-coated metal plate for containers as described.   The resin-coated metal sheet for containers according to any one of claims 1 to 6, wherein the (i) polyester resin is a polyester resin containing diphenolic acid as an essential component.   The polyester film (a2) is a biaxially stretched polyester film in which 85 mass% or more of the structural units of the polyester resin are ethylene terephthalate units and / or ethylene naphthalate units, and the biaxially stretched polyester film comprises inorganic particles and / or Or the organic particle is contained, The resin-coated metal plate for containers as described in any one of Claims 2-7 characterized by the above-mentioned.