JP2018053302A - Metal plate having surface coated with organic resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a metal plate having a surface coated with an organic resin that can provide a can body and a can top having excellent heat resistance and water adhesion and therefore capable of being subjected to germicidal treatments such as a pasteurizing treatment or a retort treatment after the contents are charged, and has excellent economical efficiency and small loads on the environment.SOLUTION: The present invention provides a metal plate having a surface coated with an organic resin, the metal plate comprising, on at least one face thereof, a surface treatment skin layer, and an organic resin coating layer on the surface treatment skin layer. The surface treatment skin layer contains a polymer of polycarboxylic acid as a major component, and polyalcohol as a crosslinking component of the polycarboxylic polymer.SELECTED DRAWING: None

Description

  The present invention relates to an organic resin-coated surface-treated metal plate used for can bodies and can lids such as beverage cans, and more specifically, it is excellent in being able to cope with sterilization treatment performed after filling the contents. The present invention relates to an organic resin-coated surface-treated metal plate that can provide a can body and a can lid having heat-resistant water adhesion, is excellent in economic efficiency, and has a low environmental load.

  An organic resin-coated metal plate obtained by coating a metal plate such as aluminum with an organic resin has been known for a long time as a material for cans, and this organic resin-coated metal plate is subjected to drawing processing or drawing / ironing processing to provide beverages, etc. It is also well known that a seamless can for filling a can or a can lid such as an easy open end by press molding it. For example, an organic resin-coated metal plate having a thermoplastic resin film made of a polyester resin mainly composed of ethylene terephthalate units as an organic resin coating layer is used as a can-making material for seamless cans (Patent Document 1).

  In addition, as a metal plate used for such an organic resin-coated metal plate for can bodies and can lids, in general, for the purpose of ensuring corrosion resistance and adhesion with the organic resin coating layer, a surface such as chemical conversion treatment A treated surface-treated metal plate is used. As such a surface treatment, for example, there is a phosphoric acid chromate treatment, and when an organic resin-coated surface-treated metal plate made of a surface-treated metal plate subjected to a phosphoric acid chromate treatment is used to form a seamless can or the like, It has been widely used because of its excellent ability to make cans and excellent adhesion between the organic resin coating layer and the metal substrate during heat sterilization after filling and sealing the contents (heat resistant water adhesion). There is an increasing demand for non-chromium surface treatment from the viewpoint of protection.

  Many non-chromium surface treatments for can materials have been proposed so far. For example, for organic resin-coated seamless aluminum cans, chemical conversion treatment of organic-inorganic composites using zirconium compounds, phosphorus compounds, and phenol compounds has been proposed, and can exhibit excellent can-making suitability and hot water adhesion (Patent Document 2). However, since the surface treatment proposed above is a chemical (reaction type) surface treatment that requires washing after the treatment, a large amount of waste water is generated, so that waste water treatment is costly and environmentally friendly. There is a concern that the load of

  On the other hand, unlike chemical molding surface treatments, non-chromium surface treatment by coating-type surface treatment (coating-type treatment) that requires no water washing after treatment, reduces the cost of wastewater treatment, and has a low environmental impact It has been proposed for industrial materials. For example, there has been proposed a resin-coated aluminum plate on which a coating-type undercoat comprising a zirconium compound and zirconium-crosslinked polyacrylic acid is formed (Patent Document 3).

JP 2001-246695 A JP 2007-76012 A JP 2007-176072 A

  However, the coating-type undercoat proposed in Patent Document 3 has been proposed particularly for resin-coated aluminum plates for cap molding, and was suitable for molding into caps with a small amount of processing. However, when it is applied to an organic resin-coated metal plate for a seamless can that is formed by a more severe molding process than a cap, there are the following problems. That is, when seamless cans are formed using them, post-processing (necking) mainly for can body molding during pasteurization treatment (hot water shower treatment) and retort treatment after filling and sealing the contents Processing and flange processing), the organic resin coating layer may peel off due to lack of heat-resistant water adhesion between the organic resin coating layer and the metal substrate. Further improvements are needed to apply.

  Therefore, the object of the present invention is to have excellent hot water adhesion that can suppress the peeling of the organic resin coating layer in the flange portion even when applied under high temperature / humid environment such as pastorise treatment and retort treatment after filling the contents. It is an object to provide an organic resin-coated surface-treated metal sheet having a surface-treated film layer formed by a non-chromium coating type treatment that has excellent properties, is economical, and has a low environmental impact.

As a result of intensive studies, the present inventors have found that at least one side of the metal plate contains a polycarboxylic acid polymer such as polyacrylic acid as a main component and a polyalcohol as a crosslinking component of the polycarboxylic acid polymer, An organic resin-coated surface-treated metal plate having a surface-treated film layer in which a carboxylic acid polymer and a polyalcohol form a cross-linked structure, and an organic resin-coated layer formed on the surface-treated film layer is filled with contents. It is possible to provide a can body having excellent hot water adhesion that can suppress peeling of the organic resin coating layer in the flange portion even when subjected to a high temperature / humid environment such as a past paste treatment or a retort treatment. As a result, the present invention has been completed.
That is, according to the present invention, there is provided an organic resin-coated surface-treated metal plate in which a surface-treated film layer and an organic resin coating layer are formed on the surface-treated film layer on at least one surface of the metal plate, There is provided an organic resin-coated surface-treated metal sheet, wherein the layer contains a polycarboxylic acid polymer as a main component and a polyalcohol as a cross-linking component of the polycarboxylic acid polymer.

In the organic resin-coated surface-treated metal plate of the present invention,
1. The content of the polyalcohol in the surface treatment film layer is 20 parts by mass or less with respect to 100 parts by mass of the solid content of the polycarboxylic acid polymer,
2. The polycarboxylic acid polymer is polyacrylic acid;
3. The polyalcohol is polyvinyl alcohol or starch;
4). The coating weight per unit area of the surface treatment coating layer is ² to 100 mg / m ² in terms of carbon atoms,
5. The organic resin coating layer is a polyester resin film;
6). The metal plate is an aluminum plate;
Is preferred.

  According to the present invention, there is also provided a can body or a can lid comprising the above organic resin-coated surface-treated metal plate.

With the organic resin-coated surface-treated metal plate of the present invention, it is possible to provide a can body / can lid having excellent heat-resistant water adhesion that can be applied to sterilization treatment performed after filling the contents.
Moreover, since the surface-treated film layer of the present invention is formed by a non-chromium coating type treatment, there are advantages that it is excellent in economic efficiency and has a low environmental load.

The above-described operational effects of the present invention are also apparent from the results of the examples described later.
A polycarboxylic acid polymer such as polyacrylic acid as a main component, a surface treatment film layer containing a polyalcohol as a crosslinking component of the polycarboxylic acid polymer, and an organic resin coating layer formed on the surface treatment film layer In the case where a seamless can was produced using the organic resin-coated surface-treated metal plate formed as described above, peeling of the organic resin coating was prevented in the hot water adhesion evaluation (Examples 1 to 18).
On the other hand, an organic resin-coated surface-treated metal plate having a surface-treated film layer formed only of a polycarboxylic acid-based polymer, or a polyalcohol alone, without blending a polyalcohol as a crosslinking component. In an organic surface-treated metal plate having a surface-treated film layer that does not contain an acid polymer, peeling of the organic resin coating layer occurs at the flange portion (Comparative Examples 1 and 2).

It is a figure which shows an example of the cross-section of the organic resin coating surface treatment metal plate of this invention.

(Surface treatment film layer)
It is an important feature that the surface treatment film layer in the organic resin surface-treated metal plate of the present invention contains at least a polycarboxylic acid polymer as a main component and a polyalcohol as a crosslinking component of the polycarboxylic polymer. In this way, it is possible to provide a can having excellent hot water adhesion. The effects of the present invention are presumed as follows.
After the surface treatment film layer containing the polycarboxylic acid polymer and the polyalcohol is formed on the metal plate, when subjected to heat treatment (about 200 ° C.) under specific conditions, The esterification reaction occurs between the carboxyl group contained in the polycarboxylic acid polymer and the hydroxyl group contained in the polyalcohol, and a crosslinked structure is formed in which the polycarboxylic acid polymer is crosslinked with the polyalcohol. It is done. By this crosslinking, the hot water resistance of the polycarboxylic acid polymer as the main component is remarkably improved, and the film retains sufficient strength even when applied in a high temperature / humid environment such as sterilization treatment. Is possible. On the other hand, the free carboxyl group (carboxyl group that does not form an ester bond with the hydroxyl group of the polyalcohol) contained in the polycarboxylic acid polymer strongly interacts with the organic resin coating layer formed on the surface treatment film layer. Therefore, the film and the organic resin coating layer can be satisfactorily adhered to each other through this free carboxyl group even when applied in a high temperature / humid environment. By combining these effects, the can molded from the organic resin-coated surface-treated metal plate of the present invention is prevented from peeling off the organic resin coating layer even when subjected to sterilization treatment after filling the contents. It is believed that it exhibits excellent hot water adhesion.

  As a composition of the surface treatment film layer in the organic resin-coated surface-treated metal plate of the present invention, polyalcohol is 20 parts by mass or less, particularly 0.1 to 20 parts per 100 parts by mass of the solid content of the polycarboxylic acid polymer. It is suitable that it is contained in an amount of part by mass, preferably less than 0.1 to 10 parts by mass, particularly preferably 0.5 to 5 parts by mass. When the amount of polyalcohol is larger than the above range, the surface treatment film layer is formed on the metal substrate during severe processing such as molding of a can body by excessively forming a cross-linkage compared to the case of being in the above range. As a result, the organic resin coating layer may be peeled off at the end of the can in the heat treatment step performed to relieve the distortion of the organic resin coating layer after molding the can. The aptitude may be significantly deteriorated, and the adhesiveness to the hot water may be deteriorated. On the other hand, when the amount of polyalcohol is less than the above range, the heat treatment and water resistance of the surface treatment film layer are insufficient due to the insufficient cross-linking as compared with the case where the polyalcohol is in the above range, and the film during sterilization treatment. The strength cannot be maintained, and internal destruction tends to occur. As a result, the organic resin coating layer may be peeled off, and the heat resistant water adhesion may be deteriorated. Also in the heat treatment step after can body molding, due to lack of heat resistance, the coating is liable to be internally destroyed, which may cause the organic resin coating layer to peel off, possibly degrading the ability to make cans.

In the present invention, the coating weight per unit area of the surface treatment coating layer is preferably in the range of ² to 100 mg / m ² , particularly 5 to 50 mg / m ^{2 in} terms of carbon atoms. When the film weight is larger than the above range, the film becomes thicker than necessary, which is uneconomical. On the other hand, when the content is smaller than the above range, the film is thinner than the required film thickness, and there is a possibility that sufficient hot water adhesion with the organic resin coating layer cannot be obtained. Further, the thickness of the surface treatment film layer is preferably less than 0.1 μm, particularly preferably in the range of 0.005 to 0.05 μm.

(Polycarboxylic acid polymer)
As the polycarboxylic acid polymer constituting the surface treatment film layer in the present invention, an existing polycarboxylic acid polymer can be used. However, there are two existing polycarboxylic acid polymers in the molecule. It is a general term for polymers having the above carboxyl groups. Specifically, a homopolymer using an ethylenically unsaturated carboxylic acid as a polymerizable monomer, and only an ethylenically unsaturated carboxylic acid as a monomer component, and at least two copolymers thereof In addition, a copolymer of an ethylenically unsaturated carboxylic acid and another ethylenically unsaturated monomer, and an acidic polysaccharide having a carboxyl group in the molecule such as alginic acid, carboxymethylcellulose, and pectin can be exemplified. These polycarboxylic acid polymers can be used alone or as a mixture of at least two polycarboxylic acid polymers.

  Here, as the ethylenically unsaturated carboxylic acid, acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid and the like are representative, among which acrylic acid, methacrylic acid, itaconic acid, maleic acid Is preferred. In addition, ethylenically unsaturated monomers copolymerizable with them include α-olefins such as ethylene and propylene, carboxylic acid vinyl esters such as vinyl acetate, alkyl acrylate, alkyl methacrylate, and alkyl itaconate. Representative examples include carboxylic acid esters, acrylonitrile, vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride, acrylamide, styrene, and the like.

  Among such polycarboxylic acid polymers, a polymer containing a structural unit derived from at least one polymerizable monomer selected from acrylic acid, methacrylic acid, itaconic acid and maleic acid, or A mixture of polymers is preferred. The polymer may be a homopolymer or a copolymer. In the polymer, the constituent unit derived from at least one polymerizable monomer selected from the acrylic acid, maleic acid, methacrylic acid, and itaconic acid is 60 mol% or more, preferably 80 mol% or more. , And most preferably, it is contained in an amount of 100 mol% (however, all the structural units are 100 mol%). That is, the polycarboxylic acid polymer is preferably a polymer composed of at least one polymerizable monomer selected from the acrylic acid, maleic acid, methacrylic acid, and itaconic acid. In addition, when structural units other than the said structural unit are contained, as another structural unit, the ethylenically unsaturated monomer copolymerizable with the above-mentioned ethylenically unsaturated carboxylic acid etc. are mentioned, for example. Further, when the polycarboxylic acid polymer is a polymer composed of at least one polymerizable monomer selected from acrylic acid, maleic acid, methacrylic acid, and itaconic acid, the polymerizable monomer A monomeric homopolymer, copolymer, or a mixture thereof can be used. More preferably, polyacrylic acid, polymethacrylic acid, polyitaconic acid, polymaleic acid, and mixtures thereof can be used. In the present invention, the polycarboxylic acid polymer is particularly preferably polyacrylic acid.

  In addition, in the polycarboxylic acid polymer used in the present invention, a part of the carboxyl group of the polycarboxylic acid polymer may be previously neutralized with a basic compound as long as the object of the present invention is not impaired. . Examples of the basic compound include alkali metal hydroxides such as sodium hydroxide, potassium hydroxide and lithium hydroxide, and various amine compounds such as ammonia.

  The polycarboxylic acid polymer constituting the surface treatment film layer of the present invention is not limited to this, but the weight average molecular weight (Mw) is 3,000 to 1,000,000, preferably 10,000 to 1,000. In the range of 1,000. When the weight average molecular weight is smaller than the above range, the heat resistant water adhesion of the surface treatment film layer may be deteriorated. On the other hand, when the weight average molecular weight is larger than the above range, the stability of the surface treatment liquid is lowered, and there is a risk of gelation with time, which may be inferior in productivity.

(Polyalcohol)
Examples of the polyalcohol constituting the surface treatment film layer in the present invention include low molecular weight polyalcohol having two or more hydroxyl groups in the molecule, polyalcohol polymer, saccharide and the like.
Low molecular weight polyalcohols include ethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol, 1,6-hexylene glycol, diethylene glycol, triethylene glycol, cyclohexane dimethanol, ethylene oxide adduct of bisphenol A, Examples include trimethylolpropane, erythritol, pentaerythritol, glycerin, xylitol, arabitol, sorbitol, mannitol and the like.
Polyalcohol polymers include polyvinyl alcohol (hereinafter sometimes referred to as “PVA”), partially saponified polyvinyl acetate, butenediol-vinyl alcohol copolymer resin, polyhydroxyethyl (meth) acrylate, polyethylene glycol. , Polypropylene glycol, ethylene-vinyl alcohol copolymer and the like.
Further, examples of the saccharide include monosaccharides such as arabinose, xylose, ribose, lyxose, glucose, mannose, galactose, and fructose, oligosaccharides such as sucrose, maltose, cellobiose, and lactose, and polysaccharides such as starches and dextrins. .
In the present invention, among the polyalcohols, PVA, butenediol-vinyl alcohol copolymer resin, starches, glycerin, and polyethylene glycol can be preferably used, and PVA and starches are particularly preferable.
Although it does not specifically limit as PVA, A saponification degree is 85% or more, Preferably it is 95% or more, and an average degree of polymerization can be used suitably for the range of 50-5000.
As the starch, water-soluble soluble starch can be preferably used.

(catalyst)
For the purpose of promoting the esterification reaction by heat treatment of the polycarboxylic acid polymer and the polyalcohol, a metal salt of an inorganic acid or an organic acid can be appropriately added as a catalyst. Examples of the metal include alkali metals such as lithium, sodium and potassium. Specific examples of inorganic or organic acid metal salts include lithium chloride, sodium chloride, potassium chloride, sodium bromide, sodium hypophosphite, disodium hydrogen phosphite, disodium phosphate, sodium ascorbate Sodium acetate, sodium benzoate, sodium hyposulfite and the like, and sodium hypophosphite is particularly preferred. The addition amount of the metal salt of an inorganic acid and an organic acid is 0.1-10 mass parts with respect to 100 mass parts of solid content of a polycarboxylic acid type polymer, Preferably it is 0.2-5 mass parts.

  Moreover, the surface treatment film layer in the present invention may contain a polyvalent metal compound such as zirconium, zinc, calcium, and aluminum as long as the object of the present invention is not impaired.

(Surface treatment liquid)
The surface treatment liquid for forming the surface treatment film layer of the present invention can be formed from a surface treatment liquid containing a polycarboxylic acid polymer, a polyalcohol, an aqueous medium, and, if necessary, an esterification reaction catalyst. In such a surface treatment solution, the polyalcohol is 0.1 to 20 parts by weight, preferably less than 0.1 to 10 parts by weight, particularly preferably based on 100 parts by weight of the solid content of the polycarboxylic acid polymer. It is suitable to contain in the quantity of 0.5-5 mass parts. When a metal salt of an inorganic acid and an organic acid is added as a catalyst to the surface treatment liquid, the amount of the metal salt of an inorganic acid and an organic acid is 0 in terms of solid content per 100 parts by mass of the polycarboxylic acid polymer. It is suitable to mix | blend in the quantity of 0.1-10 mass parts, Preferably 0.2-5 mass parts.

  As said aqueous medium, water, such as distilled water, ion-exchange water, and pure water, can be used, and it contains organic solvents, such as alcohol, a polyhydric alcohol, its derivative (s) like a well-known aqueous composition. Can do. When using such a co-solvent, it can contain in the quantity of 5 to 30 weight% with respect to water. By containing the solvent in the above range, the film forming performance is improved. Examples of such organic solvents include methyl alcohol, ethyl alcohol, isopropyl alcohol, propylene glycol monopropyl ether, ethylene glycol monoble ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol mono Examples include butyl ether, tripropylene glycol monomethyl ether, and 3-methyl 3-methoxybutanol.

(Method for forming surface treatment film layer on metal plate)
The method for forming the surface treatment film layer on the metal plate is not particularly limited. For example, the metal plate is subjected to a degreasing treatment as a surface cleaning (pretreatment) for removing rolling oil, rust preventive oil, etc., and then washed with water. Then, the surface treatment film layer can be formed by applying the surface treatment liquid on the metal plate and heating and drying.

  It does not specifically limit as said degreasing process, For example, the alkali washing | cleaning and acid washing which were conventionally used for the degreasing process of metal plates, such as aluminum and aluminum alloy, can be mentioned. In the present invention, from the viewpoint of adhesion between the surface-treated film layer and the metal substrate, a method of further performing acid cleaning after alkali cleaning, or a method of performing acid cleaning without performing the alkali cleaning is preferable. . In the degreasing treatment, the alkali cleaning is usually performed using an alkaline cleaner, and the acid cleaning is performed using an acidic cleaner.

  It does not specifically limit as said alkaline cleaner, For example, what is used for normal alkali washing | cleaning can be used, for example, "Surf cleaner 420N-2" by Nippon Paint, etc. are mentioned. It does not specifically limit as said acidic cleaner, For example, aqueous solution, such as inorganic acids, such as a sulfuric acid, nitric acid, and hydrochloric acid, is mentioned. After performing the above degreasing treatment, in order to remove the degreasing agent remaining on the surface of the metal plate, after performing the water washing treatment, the water on the surface of the metal plate is removed by a method such as air blowing or hot air drying. .

  Surface treatment liquid is roll coat method, spray method, dipping method, brush coating method, spray squeezing method (After spraying the surface treatment liquid on the metal plate by spraying, the liquid film is squeezed with roll or air and dried) , After the surface treatment, the metal plate can be applied and treated by a conventionally known method such as immersion drawing (after immersing the metal plate in the surface treatment liquid and then strongly squeezing and drying the liquid film with a roll or air). The drying conditions are 50 to 300 ° C. and 5 seconds to 5 minutes, and preferably 150 to 250 ° C. and 10 seconds to 2 minutes.

(Metal plate)
Although it does not specifically limit as a metal plate used for this invention, Various steel plates, an aluminum plate, etc. are used. As the steel plate, a cold-rolled steel plate annealed and then cold-rolled secondary can be used, and a clad steel plate or the like can also be used. As the aluminum plate, an aluminum plate made of an aluminum alloy in addition to so-called pure aluminum can be used. In the present invention, an aluminum plate made of an aluminum alloy can be particularly preferably used. Suitable examples of the aluminum plate include aluminum alloy 5182, aluminum alloy 5021, aluminum alloy 5022, aluminum alloy 5052, aluminum alloy 3004, aluminum alloy 3005, aluminum alloy 3104, and aluminum alloy 1100. Used for.
The original thickness of the metal plate is not particularly limited and varies depending on the type of metal and the use or size of the container, but the metal plate generally has a thickness of 0.10 to 0.50 mm. In the case of, the thickness is preferably 0.10 to 0.30 mm, and in the case of an aluminum plate, the thickness is preferably 0.15 to 0.40 mm. If the thickness is less than 0.15 mm, it is difficult to mold the lid, and a desired lid strength cannot be obtained. On the other hand, if the thickness exceeds 0.40 mm, the economic efficiency deteriorates.

In the present invention, a metal plate that has been previously subjected to a surface treatment such as chemical conversion treatment or plating may be used.
As the above-mentioned surface treatment, when using a steel plate as a metal plate, one or more surface treatments such as zinc plating, tin plating, nickel plating, electrolytic chromic acid treatment, chromic acid treatment, and phosphate treatment are used. You can list what you have done. When an aluminum plate is used as the metal plate, water-soluble resins such as acrylic resin and phenol resin are used for inorganic chemical conversion treatment such as phosphate chromate treatment, zirconium phosphate treatment, and phosphate treatment, and inorganic chemical conversion treatment. And organic-inorganic composite chemical conversion treatment combining organic components such as tannic acid.

(Organic resin coating layer)
In the organic resin-coated metal plate of the present invention, the organic resin constituting the organic resin coating layer directly applied on the surface treatment film layer formed on the metal plate is not particularly limited, for example, crystalline polypropylene, Crystalline propylene-ethylene copolymer, crystalline polybutene-1, crystalline poly-4-methylpentene-1, low-, medium-, or high-density polyethylene, ethylene-vinyl acetate copolymer (EVA), ethylene-acrylic Polyolefins such as ethyl acid copolymer (EEA) and ion-crosslinked olefin copolymer (ionomer); Aromatic vinyl copolymers such as polystyrene and styrene-butadiene copolymer; Halogens such as polyvinyl chloride and vinylidene chloride resin Vinyl polymer; acrylonitrile-styrene copolymer, acrylonitrile-styrene-butadiene copolymer Nitrile polymers such as nylon; polyamides such as nylon 6, nylon 66, para or metaxylylene adipamide; polyesters such as polyethylene terephthalate (PET) and polytetramethylene terephthalate; various polycarbonates; polyacetals such as polyoxymethylene Thermoplastic resins such as these can be mentioned, and a thermoplastic resin film composed of these thermoplastic resins can be used as the organic resin coating layer. Among these, a polyester resin film composed of a polyester resin is particularly suitable as a thermoplastic resin.

The polyester resin constituting the polyester resin film may be homopolyethylene terephthalate, an acid component other than terephthalic acid in an amount of 30 mol% or less based on the acid component, and an alcohol component other than ethylene glycol as alcohol. It may be a copolyester alone or a blend thereof containing 30 mol% or less on a component basis.
Examples of the acid component other than terephthalic acid include isophthalic acid, naphthalenedicarboxylic acid, cyclohexanedicarboxylic acid, P-β-oxyethoxybenzoic acid, diphenoxyethane-4,4′-dicarboxylic acid, 5-sodium sulfoisophthalic acid, hexa Examples include hydroterephthalic acid, succinic acid, adipic acid, sebacic acid, dodecanedioic acid, dimer acid, trimellitic acid, and pyromellitic acid.
Examples of alcohol components other than ethylene glycol include propylene glycol, 1,4-butanediol, neopentyl glycol, 1,6-hexylene glycol, diethylene glycol, triethylene glycol, cyclohexanedimethanol, and ethylene oxide adduct of bisphenol A, Examples include glycol components such as trimethylolpropane and pentaerythritol.
Further, a homopolyethylene terephthalate resin and / or a copolymerized polyester resin mainly composed of polyethylene terephthalate and crystalline polyester resins other than these, for example, a homopolybutylene terephthalate resin and / or a copolymerized polyester resin mainly composed of a polybutylene terephthalate resin, Alternatively, it may be a resin blended with a homopolyethylene naphthalate resin and / or a copolymer polyester resin mainly composed of a polyethylene naphthalate resin. In that case, the crystalline polyester resin other than the homopolyethylene terephthalate resin and / or the copolyester resin mainly composed of the polyethylene terephthalate resin with respect to the copolyester resin mainly composed of the homopolyethylene terephthalate resin and / or the polyethylene terephthalate resin. It is preferable that the compounding quantity of 5-50 wt%.

  Among the above polyester resins, in particular, polyethylene terephthalate resin composed of ethylene terephthalate units, polyethylene terephthalate / polyethylene isophthalate copolymer resin, polyethylene terephthalate / polybutylene terephthalate copolymer resin, polyethylene terephthalate / polyethylene naphthalate copolymer resin, polyethylene terephthalate resin, and It is preferably one of a blend resin of polybutylene terephthalate resin, a blend resin of polyethylene terephthalate / polyethylene isophthalate copolymer resin and polybutylene terephthalate resin, particularly polyethylene terephthalate / polyethylene isophthalate copolymer resin, polyethylene terephthalate / polyethylene Isophthalate copolymer resin and polybutylene Blend resin of phthalate resin is preferable. The polyethylene terephthalate / polyethylene isophthalate copolymer resin preferably has an isophthalic acid content of 20 mol% or less (acid component basis). The blend resin of the polyethylene terephthalate / polyethylene isophthalate copolymer resin and the polybutylene terephthalate resin is a blend of polybutylene terephthalate resin in a range of 10 to 50 wt% with respect to the polyethylene terephthalate / polyethylene isophthalate copolymer resin. preferable.

  The polyester resin used as the organic resin coating layer should have a molecular weight in the range of film formation, and the intrinsic viscosity [η] measured using a phenol / tetrachloroethane mixed solvent as the solvent is 0.5 or more, especially 0.8. The range of 52 to 0.70 is preferable from the viewpoint of barrier properties against mechanical components and mechanical properties, and the glass transition point is preferably 50 ° C. or higher, particularly 60 ° C. to 80 ° C.

In a thermoplastic resin film such as a polyester resin film, per se known film compounding agents, lubricants, antiblocking agents, pigments, various antistatic agents, antioxidants, and the like can be blended according to known formulations.
In general, the thickness of a thermoplastic resin film such as a polyester resin film is preferably in the range of 5 to 40 μm.
The organic resin coating layer made of a thermoplastic resin film can be made into a two-layer structure. When a polyester resin is used as the thermoplastic resin, the lower layer is mainly composed of ethylene terephthalate units, such as isophthalic acid and naphthalenedicarboxylic acid. It contains at least one kind in an amount of 1 to 30 mol% (based on acid component) and is formed from a polyester resin whose amount is larger than the compounding amount of the acid component in the upper polyester resin. It is particularly suitable from the viewpoint of dent resistance and the like.

The organic resin coating layer made of a thermoplastic resin film may be formed on the surface treatment film layer through a conventionally known adhesive primer layer such as epoxy phenol or polyester phenol. The adhesion primer layer exhibits excellent adhesion to both the surface treatment film layer and the organic resin coating layer.
The epoxy phenolic adhesion primer is particularly preferably formed from a paint containing an epoxy resin and a phenol resin in a weight ratio of 50:50 to 99: 1, particularly 60:40 to 95: 5. From the viewpoints of heat resistance and corrosion resistance.
The polyester phenol-based adhesive primer is particularly preferably formed from a paint containing a polyester resin and a phenol resin in a weight ratio of 50:50 to 99: 1, particularly 60:40 to 95: 5. From the viewpoints of heat resistance and corrosion resistance.
In general, the adhesive primer layer is preferably 0.1 to 10 μm thick. The adhesion primer layer may be provided in advance on the surface treatment film layer on the surface treatment metal plate, or may be provided on the organic resin coating layer such as the polyester resin film.

In the organic resin-coated surface-treated metal plate of the present invention, a coating film made of the resin coating composition can be used as the organic resin coating layer. Examples of resin coating compositions that can be suitably used include thermosetting resin coatings such as phenol resins, melamine resins, alkyd resins, unsaturated polyester resins, epoxy resins, epoxy acrylic resins, epoxy phenol resins, epoxy urea resins, and bismaleimides. Resin paint, triallyl cyanurate resin, thermosetting acrylic resin, silicone resin, oil-based resin paint, or thermoplastic resin paint such as vinyl organosol, vinyl chloride-vinyl acetate copolymer, vinyl chloride-acetic acid Examples thereof include resin coatings using partially saponified vinyl copolymers, vinyl chloride-maleic acid copolymers, vinyl chloride-maleic acid-vinyl acetate copolymers, acrylic polymers, saturated polyester resins, and the like. These resin paints may be used alone or in combination of two or more. Among these, a coating film made of a resin coating using one or more of polyester resin, phenol resin, epoxy resin, epoxy acrylic resin, epoxy phenol resin, epoxy urea resin, and vinyl organosol is preferable. .
In addition, as for the suitable dry coating film mass of the said coating film, 5-200 mg / dm < ² > is preferable.

(Method for forming organic resin coating layer on surface-treated metal plate)
As a method for forming the organic resin coating layer on the surface-treated metal plate, when the organic resin coating layer is a thermoplastic resin film, for example, after forming the thermoplastic resin film in advance by a conventionally known method, A method of coating on the treated metal plate by a thermal bonding method, an extrusion laminating method in which a heat-melted thermoplastic resin is extruded into a film using an extruder and directly coated on the surface-treated metal plate are suitable. When the thermoplastic resin film is formed and then coated, the film may be stretched, but an unstretched film is preferable from the viewpoint of molding processability and dent resistance.
When the organic resin coating layer is a coating film, it can be formed by applying a coating composition on a surface-treated plate by a conventionally known method such as a roll coating method or a spray method, followed by drying and baking. .

  FIG. 1 shows an example of a cross-sectional structure of an organic resin-coated surface-treated metal plate of the present invention. This organic resin-coated surface-treated metal plate 1 is a surface-treated film layer 3a applied to both surfaces of a metal plate 2. , 3b and organic resin coating layers 4a, 4b. In the specific example shown in FIG. 1, the organic resin coating layers 4a and 4b are formed on both the inner and outer surfaces of the metal plate 2 via the surface treatment coating layers 3a and 3b. In the treated metal plate, the surface treatment coating layer 3 and the organic resin coating layer 4 may be formed on at least one side, and different surface treatment coating layers and organic resin coating layers may be formed on the other side. it can.

(Can body and its manufacturing method)
The can body comprising the organic resin-coated surface-treated metal plate of the present invention can be produced by a conventionally known molding method.
The organic resin-coated surface-treated metal-coated metal plate of the present invention has a drawing process, drawing / deep drawing process, drawing / ironing process, drawing / bending / extending process, because the organic resin coating layer has excellent processing adhesion. -Seamless cans formed by severe processing such as ironing can be formed without causing peeling of the resin coating on the broken body or flange forming portion.
The side wall portion of the seamless can is 20-95%, particularly 25-85% of the original thickness of the organic resin-coated surface-treated metal plate by bending and stretching by drawing-redrawing or further ironing of the organic resin-coated surface-treated metal plate. It is preferable that the thickness is reduced so that the thickness becomes.
The obtained seamless can is subjected to at least one stage of heat treatment, the residual distortion of the film generated by the processing is removed, the lubricant used in the processing is volatilized from the surface, and the printing ink printed on the surface is dried and cured. The container after the heat treatment is rapidly cooled or allowed to cool, and then subjected to a one-stage or multi-stage neck-in process if necessary, and a flange process is performed to obtain a can for winding. In addition, after forming a seamless can, the upper part of the seamless can can be transformed into a bottle shape.

(Can lid and its manufacturing method)
The can lid formed of the organic resin-coated surface-treated metal plate of the present invention can be formed by a conventionally known can lid manufacturing method.
As an organic resin-coated surface-treated metal plate particularly suitable for forming can lids, an organic resin in which a polyester resin film is formed as an organic resin coating layer through the above-mentioned epoxy phenol-based or polyester phenol-based adhesive primer layer, etc. A coated surface-treated metal plate can be mentioned, and the adhesive primer layer is preferably formed with a dry film thickness of 0.3 to 3 μm.
Also suitable as an organic resin coating layer is an organic resin-coated surface-treated metal plate on which a coating made of an epoxy phenol paint, epoxy acrylic paint, polyester paint, epoxy urea paint, vinyl organosol paint, etc. is formed. Can be used.

The shape of the can lid may be a conventionally known shape such as an easy-open lid provided with a score for opening the contents extraction opening and a tab for opening, or a full open type or partial open type. Any of the types (stay on tab type) may be used.
The easy open lid is formed by first stamping an organic resin-coated metal plate into a disk shape and forming it into a desired lid shape in a press molding process. Next, in the score marking step, the score is stamped using a score die so that the score reaches the middle in the thickness direction of the metal material from the outer surface side of the lid. In the rivet forming process, a rivet that protrudes to the outer surface is formed on the planned opening section partitioned by the score using a rivet forming die, and in the tab mounting process, the opening tab is fitted to the rivet, and the protruding part of the rivet is The easy open lid is formed by taking out and fixing the tab.

  EXAMPLES Hereinafter, although a specific Example is given and this invention is demonstrated in detail, this invention is not limited by a following example. In the following description, “part” means “part by mass”.

[Examples 1 to 18]
(Preparation of surface treatment solution)
The polycarboxylic acid polymer was dissolved in ion-exchanged water to obtain a 2% by mass polycarboxylic acid polymer aqueous solution. The polyalcohol was dissolved in ion-exchanged water to obtain a 2% by mass aqueous polyalcohol solution. Subsequently, the polyalcohol aqueous solution was gradually added to the polycarboxylic acid polymer aqueous solution with stirring at room temperature so as to obtain a predetermined blending ratio. Further, when the catalyst was blended, an aqueous solution of the catalyst was prepared and added to the aqueous solution containing the polycarboxylic acid polymer and the polyalcohol while stirring at room temperature so as to obtain a predetermined blending ratio. Next, ion-exchanged water was added while stirring, and the solid content concentration of the polycarboxylic acid polymer in the aqueous solution was adjusted to 0.5 to 1% by mass to obtain a surface treatment liquid.

  Examples of the polycarboxylic acid-based polymer include polyacrylic acid (“Durimer AC-10L, Mw = about 50,000” manufactured by Toagosei Co., Ltd .: “PAA1” in the table, “Durimer AC-10H, Mw = about 800, 000 ": indicated as" PAA2 "in the table). As the polyalcohol, polyvinyl alcohol (manufactured by Wako Pure Chemical Industries, Ltd., “polyvinyl alcohol 500 complete saponification type, average polymerization degree 400 to 600, saponification degree 96% or more”): “PVA1” in the table, “polyvinyl alcohol 3500 parts saponification type, Average degree of polymerization = 3100-3900, degree of saponification = 86-90% ”:“ PVA2 ”in the table), soluble starch (“ starch, soluble ”manufactured by Wako Pure Chemical Industries, Ltd.), butenediol-vinyl alcohol copolymer resin ( “Nichigo G polymer AZF8035W” manufactured by Nippon Synthetic Chemical Co., Ltd .: “BVOH” in the table), glycerin (“glycerin” manufactured by Wako Pure Chemical Industries), polyethylene glycol (“polyethylene glycol 200 manufactured by Wako Pure Chemical Industries, average molecular weight = 180) -200 ": written as" PEG "in the table). As the catalyst, sodium hypophosphite (“sodium phosphinate monohydrate” manufactured by Wako Pure Chemical Industries, Ltd.) was used. In each Example, the types of the polycarboxylic acid polymer and polyalcohol used, and the solid content of the polyalcohol and catalyst with respect to 100 parts of the solid content of the polycarboxylic acid polymer in the surface treatment liquid are shown in Table 1. .

(Production of surface-treated metal plate)
As the metal plate, an aluminum plate (3104 alloy plate, plate thickness: 0.28 mm, plate size: 200 × 300 mm) was used. First, alkali cleaning was performed by dipping in a 2% aqueous solution (60 ° C.) of an alkaline cleaner “Surf Cleaner 420N-2” (trade name) manufactured by Nippon Paint Co., Ltd. for 6 seconds. After alkali washing, water washing, immersion in 2% sulfuric acid aqueous solution (60 ° C.) for 6 seconds, acid washing, water washing and drying. A surface treatment liquid was applied to both surfaces of the obtained metal plate, and was kept in an oven set at 200 ° C. for 60 seconds and dried to prepare a surface treated metal plate.

(Film weight measurement)
The weight per unit area (mg / m ² ) of the carbon (C) derived from the polycarboxylic acid-based polymer and the polyalcohol in the surface-treated film layer in the obtained surface-treated metal plate was measured with an X-ray fluorescence analyzer It measured using. In the measurement, first, a plurality of samples each having a known carbon weight per unit area and different carbon weights were measured, and a strength-weight calibration curve was prepared from the strength at this time. Under the same conditions, the surface-treated metal plate in each example was also measured, and the obtained measurement strength was converted to carbon weight based on the calibration curve, thereby measuring the carbon equivalent film weight of the surface treatment film layer. did. The measurement results are shown in Table 1.
Equipment used: ZSX100e manufactured by Rigaku Corporation
Measurement conditions: Measurement diameter 20 mm
X-ray output 50kV-70mA

(Production of organic resin-coated surface-treated metal plate)
The organic resin-coated surface-treated plate for cans was produced by the following method. The obtained surface-treated metal plate was previously heated to a plate temperature of 250 ° C., and a polyester resin film as an organic resin coating layer was thermocompression bonded to both surfaces of the surface-treated metal plate via a laminating roll, and then immediately cooled with water. Thus, an organic resin-coated surface-treated metal plate was obtained. As the polyester resin film, a 12 μm thick polyethylene terephthalate / polyethylene isophthalate copolymer resin film was used.

(Preparation of seamless cans)
Paraffin wax was electrostatically applied to both surfaces of the prepared organic resin-coated surface-treated metal plate for a can, and then punched into a circle having a diameter of 156 mm to produce a shallow drawn cup. Next, this shallow drawn cup is subjected to redrawing-ironing and doming, trimming of the edge of the opening, heat treatment at 201 ° C. for 75 seconds, then 210 ° C. for 80 seconds, and necking of the opening end. Then, a flanging process was performed, and a seamless can having a diameter of the can body 211 and a neck portion 206 diameter of 500 ml was produced. Various characteristics of the seamless can were as follows.
Can body diameter: 66 mm
Can height: 168mm
Average thickness reduction rate of can side wall relative to original thickness: 60%

(Comparative Example 1)
As shown in Table 1, a seamless can was produced in the same manner as in Example 1 except that a surface treatment liquid containing no polyalcohol was used.

(Comparative Example 2)
As shown in Table 1, a seamless can was produced in the same manner as in Example 1 except that a surface treatment liquid containing no polycarboxylic acid polymer was used.

(Comparative Example 3)
Surface treated aluminum plate (3104 alloy plate, plate thickness: 0.28 mm, plate size: 200 × 300 mm, chromium content in the surface treatment film: 20 mg / m ² ) subjected to phosphoric acid chromate treatment (chemical molding treatment) as a metal plate To prepare an organic resin-coated surface-treated metal plate as described in the section “Preparation of an organic resin-coated surface-treated metal sheet”, and seamlessly as described in the section “Preparation of a seamless can”. A can was made.

(Evaluation method for seamless cans)
The seamless cans obtained in Examples 1 to 18 and Comparative Examples 1 to 3 were evaluated as follows, and the results are shown in Table 1.

(Evaluation of can aptitude)
As described in the section “Preparation of seamless cans”, the flange peelability evaluation during heat treatment was performed by trimming the can body, and then using an oven at 201 ° C. for 75 seconds and then at 210 ° C. for 80 seconds. After performing heat treatment for 2 seconds, the opening end (flange forming portion) of the can body was observed with a microscope, and the degree of peeling of the organic resin coating layer was evaluated from the opening end of the can body. The evaluation results are shown in Table 1.
A: Maximum length of peeled portion is less than 0.1 mm ○: Maximum length of peeled portion is 0.1 mm or more and less than 0.2 mm Δ: Maximum length of peeled portion is 0.2 mm or more and less than 0.3 mm X: The maximum length of the peeled portion is 0.3 mm or more

(Evaluation of adhesion to hot water)
The hot water adhesion evaluation was performed as described in the above section “Preparation of seamless cans”, and then from the inner surface to the metal surface with a cutter knife along the circumference of the can from the inner diameter side neck portion to the smallest diameter portion. The peeled state of the organic resin coating layer at the neck portion after immersion in hot water at 100 ° C. for 10 minutes was observed and evaluated in a state where the scratch reached was reached. The evaluation results are shown in Table 1.
◎: No peeling is observed over the entire circumference ○: Partial peeling is observed, but the length of the peeling portion is less than 5% of the total circumference of the can △: Partial peeling is observed, but the peeling The length of the part is 5% to 10% of the total circumference of the can
Less than ×: The length of the peeled portion is 10% or more in the entire circumferential direction

  The organic resin-coated surface-treated metal plate of the present invention can peel an organic resin coating layer even when it is subjected to a high temperature / humid environment such as a sterilization process when a seamless can is molded using the metal plate. Because it can exhibit excellent hot water adhesion that can be suppressed, it can be suitably used for cans and can lids, and also has excellent hot water adhesion even when subjected to harsh molding processes Therefore, it can be suitably used for seamless cans such as squeezed iron cans.

1 organic resin-coated surface-treated metal plate, 2 metal plate, 3 surface-treated film layer, 4 organic resin-coated layer.

Claims (9)

  An organic resin-coated surface-treated metal plate comprising a surface-treated film layer and an organic resin coating layer formed on the surface-treated film layer on at least one surface of the metal plate, wherein the surface-treated film layer is a polycarboxylic acid as a main component. An organic resin-coated surface-treated metal plate comprising an acid polymer and a polyalcohol as a crosslinking component of the polycarboxylic acid polymer.   The organic resin coating according to claim 1, wherein the content of the polyalcohol in the surface treatment film layer is 20 parts by mass or less with respect to 100 parts by mass of the solid content of the polycarboxylic acid polymer. Surface treatment metal plate.   The organic resin-coated surface-treated metal sheet according to claim 1 or 2, wherein the polycarboxylic acid polymer is polyacrylic acid.   The organic resin-coated surface-treated metal sheet according to any one of claims 1 to 3, wherein the polyalcohol is polyvinyl alcohol or starch. The organic resin-coated surface-treated metal sheet according to any one of claims 1 to 4, wherein a film weight per unit area of the surface-treated film layer is ² to 100 mg / m ² in terms of carbon atoms.   The said organic resin coating layer is a polyester resin film, The organic resin coating surface-treated metal plate in any one of Claims 1-5 characterized by the above-mentioned.   The organic resin-coated surface-treated metal plate according to any one of claims 1 to 6, wherein the metal plate is an aluminum plate.   A can body comprising the organic resin-coated surface-treated metal plate according to any one of claims 1 to 7.   A can lid comprising the organic resin-coated surface-treated metal plate according to claim 1.