JP6672948B2 - Organic resin-coated seamless cans - Google Patents

Description

  The present invention relates to an organic resin-coated seamless can having a surface treatment film layer and an organic resin coating layer on the surface treatment film layer on at least one surface of the metal can, and more particularly, to an excellent can-making suitability. The present invention relates to an organic resin-coated seamless can having excellent retort resistance and capable of coping with a retort sterilization treatment performed after filling contents.

  BACKGROUND ART An organic resin-coated metal plate obtained by coating a metal plate of aluminum or the like with an organic resin has long been known as a can-making material, and the organic resin-coated metal plate is subjected to drawing or drawing / ironing to serve as a beverage or the like. It is also well-known that a seamless can for filling is used, or that this is press-formed to form a can lid such as an easy open end. For example, an organic resin-coated metal plate having a thermoplastic resin film composed 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, a metal plate used for such an organic resin coated metal plate for a seamless can is generally subjected to a surface treatment such as a chemical conversion treatment for the purpose of ensuring corrosion resistance and adhesion to the organic resin coating layer. A surface-treated metal plate is used. As such a surface treatment, there is, for example, a phosphoric acid chromate treatment, and a seamless can molded from an organic resin-coated surface treated metal plate made of a surface treated metal plate subjected to a phosphoric acid chromate treatment has excellent can-suitability. It has been widely used because it has the suitability for sterilization treatment (retort resistance) such as retort treatment (pressure and heat sterilization treatment) performed after filling and sealing the contents. The demand for system surface treatment is increasing.

  Many non-chrome surface treatments for can materials have been proposed so far. For example, for organic resin-coated seamless aluminum cans, a chemical conversion treatment of an organic-inorganic composite system using a zirconium compound and a phosphorus compound, and a phenol compound has been proposed, which can exhibit excellent can-making suitability and retort resistance. (Patent Document 2). However, the surface treatment proposed above is a chemical molding (reaction type) surface treatment that requires washing with water after the treatment, so that a large amount of wastewater is generated. There is a concern that the load on the system will be large.

  On the other hand, unlike the surface treatment of chemical molding, water washing is not required after the treatment, the cost of wastewater treatment can be reduced, and the non-chrome surface treatment by the application type surface treatment (application type treatment) that has a small burden on the environment can also be performed. It has been proposed for materials. For example, there has been proposed a resin-coated aluminum plate on which a coating-type base film containing a zirconium compound and polyacrylic acid crosslinked with zirconium is formed (Patent Document 3).

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

  However, the coating-type undercoating proposed in Patent Document 3 is particularly proposed for a resin-coated aluminum plate for cap molding, and is suitable for molding into a cap with a small processing amount. However, when the present invention is applied to an organic resin-coated metal plate for a seamless can formed by a severer molding process than a cap, there are the following problems. That is, when a seamless can is formed using the same, a post-processing (necking or flange processing) of the can body is mainly performed during a sterilization treatment such as a retort treatment after filling and sealing the contents. In some parts, the organic resin coating layer was sometimes peeled off due to insufficient adhesion between the organic resin coating layer and the metal substrate in a high temperature, high pressure, and high humidity environment. Furthermore, when the retort treatment is performed under more severe conditions, such as in a state where the side wall portion of the can body on the outer surface side of the can is partially in contact with water and subjected to heat treatment under pressure by steam, the can Due to insufficient adhesion between the organic resin coating layer and the metal base near the portion of the outer side of the can body side wall that was in contact with the water, external surface defects such as floating of the organic resin coating layer and blisters (blisters) occurred. Occurred in some cases. From the above points, it can be said that further improvement is necessary for application to seamless cans.

  Therefore, an object of the present invention is to suppress the peeling of the organic resin coating layer at the flange portion even when subjected to a high-temperature, high-pressure, high-humidity environment such as retort treatment after filling and sealing the contents, and Suppress the occurrence of blisters and other external defects even when retort processing is performed under more severe conditions, such as when the can body side wall part of the outer surface of the can is in contact with water and subjected to heat treatment under pressure by steam. An object of the present invention is to provide an organic resin-coated seamless can having a surface treatment film layer formed by a non-chromium-based coating type treatment, which has excellent retort resistance, has a low environmental load, and is economical.

According to the present invention, there is provided an organic resin-coated seamless can having at least one surface of a metal can having a surface treatment film layer and an organic resin coating layer on the surface treatment film layer, wherein the surface treatment film layer is a polycarboxylic acid type. The maximum absorption peak height (α) in the wave number range of 1660 to 1760 cm ⁻¹ when the infrared ray absorption spectrum of the surface treatment film layer containing the polymer and the zirconium compound is measured, and 1490 to 1659 cm ⁻¹ at the maximum absorption peak height in the wavenumber range (beta) peak height ratio of the (beta / alpha) is Ri der 0.10 to 2.40, organic wherein said zirconium compound does not contain fluorine A resin-coated seamless can is provided.

In the organic resin-coated seamless can of the present invention,
1. The polycarboxylic acid polymer is a homopolymer or a copolymer obtained by polymerization of at least one polymerizable monomer selected from acrylic acid, methacrylic acid, itaconic acid and maleic acid, or a polymer thereof. Being a mixture of coalescence,
2. The zirconium compound is a zirconium compound derived from an oxyzirconium salt,
3. The oxyzirconium salt is ammonium zirconium carbonate,
4. The content of the polycarboxylic acid-based polymer in the surface treatment film layer is ² to 100 mg / m ² in terms of carbon, and the content of the zirconium compound is 1 to 80 mg / m ² in terms of zirconium. ,
5. The surface-treated coating layer contains a zirconium compound in an amount of 3 to 67 parts by mass in terms of zirconium, based on 100 parts by mass of the solid content of the polycarboxylic acid polymer.
6. The surface treatment film layer further contains colloidal silica,
7. The content of the colloidal silica in the surface treatment film layer is 1 to 200 mg / m ² in terms of silicon.
8. The organic resin coating layer is a polyester resin film,
9. The seamless can is an aluminum seamless can,
Is preferred.

The present inventors have prepared a surface treatment film layer containing a polycarboxylic acid-based polymer as a main component and a zirconium compound as a cross-linking component of the polycarboxylic acid-based polymer on at least one surface of the metal can, and on the surface treatment film layer. Forming a free carboxyl group (-COOH) of a polycarboxylic acid polymer not forming a metal salt with zirconium and a metal salt with zirconium in an organic resin-coated seamless can having an organic resin coating layer formed in Maximum absorption in the wave number range of 1660 to 1760 cm ^-1 when measuring the infrared absorption spectrum of the surface-treated coating layer, which is a measure of the ratio of carboxyl groups (-COO ⁻ ) in the polycarboxylic acid polymer. peak height (alpha) between the maximum absorption peak height in the wavenumber range of 1490~1659cm ^-1 (β) with the peak height ratio (beta / alpha) is, Yes A seamless can with excellent retort resistance, which has been found to have a great effect on the retort resistance of resin-coated seamless cans, and which has excellent suitability for can making and can cope with the retort treatment under the aforementioned severe conditions. A suitable range for obtaining has been found.
This makes it possible to provide an organic resin-coated seamless can having excellent suitability for can-making and retort resistance.
In addition, since the surface treatment film layer of the present invention is formed by a non-chromium-based coating type treatment, there is an advantage that it is excellent in economic efficiency and has a small burden on the environment.

The above-mentioned effects of the present invention are apparent from the results of the examples described later.
In an organic resin-coated seamless can having a surface-treated film layer containing a polycarboxylic acid-based polymer as a main component and a zirconium compound as a crosslinking component, 1660 to 1760 cm ^-1 when measuring the infrared absorption spectrum of the surface-treated film layer The peak height ratio (β / α) of the maximum absorption peak height (α) in the wave number range of ( ¹ ) to the maximum absorption peak height (β) in the wave number range of 1490 to 1659 cm ⁻¹ exceeds 2.40. Or in an organic resin-coated seamless can having a surface treatment film layer of less than 0.10, in the evaluation of the releasability of the flange portion at the time of retort, the organic resin coating layer peeled off at the flange portion, and further under the above-mentioned more severe conditions. In the evaluation of the outer wall of the can body at the time of retorting assuming the retort treatment in Example 1, occurrence of blisters was confirmed (Comparative Examples 1 to 3). In contrast, in an organic resin-coated seamless can having a surface-treated coating layer having a peak height ratio (β / α) in the range of 0.10 to 2.40, peeling of the organic resin coating layer and generation of blisters occur. It is clear that the seamless can has excellent retort resistance. In addition, in the case of an organic resin-coated seamless can having a surface treatment film layer having a peak height ratio (β / α) of less than 0.10, a heat treatment step (heat setting step) performed after forming the can body is performed. In the flange part peeling property evaluation (canning suitability evaluation), peeling of the organic resin coating layer occurred at the opening end (flange forming part) of the can body (Comparative Examples 1 and 2). In contrast, in an organic resin-coated seamless can having a surface-treated coating layer having a peak height ratio (β / α) in the range of 0.10 to 2.40, peeling of the organic resin coating layer is suppressed. It is clear that the composition is excellent in can-making suitability. Furthermore, in the surface treatment film layer, in addition to the above-mentioned polycarboxylic acid-based polymer and zirconium compound, colloidal silica is further contained, so that the suitability for can production is further improved. As is clear from the comparison of the results of Examples 1 and 22 and 23 in the evaluation of the peelability of the flange portion during the heat treatment, in the case of the organic resin-coated seamless can having the surface treatment film layer containing colloidal silica, the flange at the open end was used. It can be seen that the occurrence of peeling of the organic resin coating layer in the formation portion is further suppressed.

3 is an infrared absorption spectrum of a surface treatment film layer of the organic resin-coated seamless can obtained in Example 1. BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing of an example of the organic resin-coated seamless can of this invention, and the figure which expands and shows the cross-section of the can body side wall part.

(Surface treatment film layer)
The surface treatment film layer in the organic resin-coated seamless can of the present invention comprises a polycarboxylic acid polymer as at least a main component and a zirconium compound as a crosslinking component of the polycarboxylic acid polymer, and the surface treatment The maximum absorption peak height (α) in the wave number range of 1660 to 1760 cm ⁻¹ and the maximum absorption peak height (β) in the wave number range of 1490 to 1659 cm ⁻¹ when measuring the infrared absorption spectrum of the coating layer. Is characterized in that the peak height ratio (β / α) is within a certain range. This is for the following reason.
In the surface treatment film layer, when the polycarboxylic acid-based polymer is cross-linked by a zirconium compound, the carboxyl group contained in the polycarboxylic acid-based polymer reacts with zirconium to form a carboxyl group and a metal salt of zirconium. You.
In infrared absorption spectrum measurement, free carboxyl groups not forming a zirconium metal salt (-COOH), within the wavenumber range of 1660～1760Cm ^-1, the carboxyl group having an absorption maximum in the vicinity of 1720 cm ^-1 C = an absorption peak derived from O stretching vibration, while the carboxyl group forming the zirconium metal salt (-COO ^-) is the wave number range of 1490～1659Cm ^-1, an absorption maximum in the vicinity of 1560 cm ^-1 2 shows an absorption peak derived from C ＝ O stretching vibration of a metal salt of a carboxyl group having the carboxyl group. The absorbance of the surface treatment film layer is proportional to the amount of the infrared-active chemical species present in the surface treatment film layer. Therefore, the maximum absorption peak height in the wavenumber range of 1660~1760cm ^-1 (α) and the maximum absorption peak height in the wavenumber range of 1490~1659cm ^-1 (β) with the peak height ratio (beta / alpha) Is a carboxyl group contained in a polycarboxylic acid polymer, a free carboxyl group not forming a metal salt with zirconium (—COOH) and a carboxyl group forming a metal salt with zirconium (—COO ⁻ ) It is a measure of the quantitative ratio. The larger this value is, the smaller the abundance ratio of free carboxyl groups (—COOH) is, while the larger the abundance ratio of carboxyl groups (—COO ⁻ ) forming a metal salt with zirconium is. Indicates that
In the surface treatment film layer in the present invention, the above-mentioned peak height ratio (β / α) is 0.10 to 2.40, preferably 0.45 to 1.60, and more preferably 0.58 to 1.45. It is particularly desirable that the ratio be in the range of 0.78 to 1.45.

The effects of the present invention are presumed as follows.
When the peak height ratio (β / α) is within the above range, free carboxyl groups (zirconium compound and metal salt) are formed on the surface of the surface treatment film layer even in a high temperature, high pressure and high humidity environment such as retort treatment. Carboxyl groups that do not form) are sufficiently present, and the surface treatment film layer and the organic resin coating layer are in good contact with each other via the free carboxyl groups, and the polycarboxylic acid polymer is appropriately moderated by the zirconium compound. By being crosslinked, the heat resistance and water resistance of the polycarboxylic acid polymer are significantly improved, and the cohesive failure of the surface treatment film layer is suppressed. As a result, the organic resin in the flange portion at the time of the above-described retort treatment is obtained. The peeling of the coating layer and the occurrence of external defects such as blisters on the side wall of the can body are suppressed, and excellent retort resistance is exhibited. In addition, even in a high-temperature environment such as a heat setting step after can body molding, the heat resistance of the polycarboxylic acid polymer is improved by crosslinking, and the cohesive failure of the surface treatment film layer is suppressed, so that the organic resin is suppressed. Peeling of the coating layer is suppressed, and excellent suitability for can-making can be exhibited.
When the peak height ratio (β / α) is larger than the above range, free carboxyl groups on the surface of the surface treatment film layer contributing to the adhesion to the organic resin coating layer are reduced, and the polycarboxylic acid weight is reduced. During severe processing from an organic resin-coated surface-treated metal plate to a seamless can due to excessive cross-linking of the coalesced zirconium, it becomes difficult for the surface-treated coating layer to follow the metal substrate, and after the can-making process Since the coatability of the surface treatment film layer is reduced, the adhesion between the surface treatment film layer and the organic resin coating layer is reduced due to these factors, and the retort resistance may be deteriorated. On the other hand, when the peak height ratio (β / α) is smaller than the above range, the surface treatment film layer is liable to undergo cohesive failure during retort treatment due to insufficient heat resistance and water resistance of the polycarboxylic acid polymer. There is a possibility that the organic resin coating layer in the flange portion may be peeled off or an outer surface defect such as a blister in the side wall of the can body may occur, the retort resistance may be deteriorated, and even in the heat setting process after the can body molding. In addition, due to lack of heat resistance, the surface treatment film layer is liable to undergo cohesive failure, whereby the organic resin coating layer may be peeled off, and the suitability for can production may be deteriorated.

In the present invention, the content of the polycarboxylic acid polymer in the surface treatment film layer is ² to 100 mg / m ² , preferably 4 to 50 mg / m ² , more preferably 6 to 40 mg / m ² in terms of carbon. in the range, and 1 to 80 mg / ^{m 2} content of zirconium in terms of zirconium compound, preferably suitably be 1 to 40 mg / ^{m 2,} more preferably in the range of 2~30mg / ^{m 2.} More specifically, for the surface-treated coating layer located on the bottom of the organic resin-coated seamless can, the content of the polycarboxylic acid polymer is 4 to 100 mg / m ² , preferably 11 to 50 mg / m ^{2 in} terms of carbon. m ² , more preferably 21 to 40 mg / m ² , and the content of the zirconium compound is ² to 80 mg / m ² , preferably ² to 40 mg / m ² , more preferably 4 to 30 mg in terms of zirconium. / M ² . On the other hand, as for the surface treatment film layer on the side wall of the can body, the content of the polycarboxylic acid-based polymer is ² to 50 mg / m ² , preferably 4 to 25 mg / m ² , more preferably 6 to 20 mg in terms of carbon. that are contained in the range of / ^{m 2,} and 1 to 40 mg / ^{m 2} content of zirconium in terms of zirconium compound, preferably 1 to 20 mg / ^{m 2,} more preferably in the range of 2 to 15 mg / ^{m 2} It is preferred that there be. When the amount of the polycarboxylic acid polymer and the zirconium compound is larger than the above range, it is difficult to adjust the peak height ratio (β / α) to the above range, or the surface treatment film layer is more than necessary. It becomes a thick film and is uneconomical. On the other hand, when the content of the polycarboxylic acid polymer or the zirconium compound is smaller than the above range, it is difficult to adjust the peak height ratio (β / α) to the above range, or The surface treatment film layer may be thinner than the required film thickness, and sufficient retort resistance may not be obtained.

When colloidal silica is further blended, the content of colloidal silica in the surface treatment film layer is 1 to 200 mg / m ² , preferably ^{2 to} 100 mg / m ² , more preferably 4 to 80 mg / m ^{2 in} terms of silicon. it is preferable in the range of m ^2. More particularly, for the surface treatment film layer located in the can bottom portion of the organic resin-coated seamless can, content of colloidal silica, 2 to 200 mg / ^{m 2} of silicon in terms of, preferably 5 to 100 mg / ^{m 2,} more Preferably, it is in the range of 10 to 80 mg / m ² . On the other hand, for the surface treatment film layer located on the side wall of the can body, the content of colloidal silica is 1 to 100 mg / m ² , preferably ² to 50 mg / m ² , more preferably 4 to 40 mg / m ^{2 in} terms of silicon. It is preferable that it is contained in the range of ² . By containing colloidal silica having excellent heat resistance within the above range in the surface treatment film layer, the heat resistance of the surface treatment film layer is further improved, and in the heat setting step after can body molding, the surface treatment film layer is formed. Of the organic resin coating layer can be further suppressed, and the suitability for can production is improved. When the content of colloidal silica is less than the above range, the above-mentioned effect cannot be expected. On the other hand, even when the amount of colloidal silica is more than the above range, no further effect is obtained, and on the contrary, retort resistance May be deteriorated.

The composition of the surface treatment film layer in the organic resin-coated seamless can of the present invention is such that the zirconium compound is 3 to 67 parts by mass, preferably 18 parts by mass, based on 100 parts by mass of the solid content of the polycarboxylic acid polymer. It is suitable that it is contained in an amount of from 52 to 52 parts by mass, more preferably from 22 to 48 parts by mass, particularly preferably from 29 to 48 parts by mass. When the amount of the zirconium compound is larger or smaller than the above range, it may be difficult to adjust the peak height ratio to the above range, and a desired effect may not be obtained. When colloidal silica is contained in the surface treatment film layer, colloidal silica is preferably 10 to 200 parts by mass, in particular as solids (silicon dioxide; SiO ₂ ), based on 100 parts by mass of the polycarboxylic acid polymer. It is preferable to contain it in an amount of 50 to 200 parts by mass. When the amount of colloidal silica is smaller than the above range, sufficient improvement in heat resistance cannot be expected.On the other hand, even when the amount of colloidal silica is larger than the above range, no further improvement in heat resistance can be obtained. Retort resistance may be degraded.

(Polycarboxylic acid polymer)
In the present invention, as the polycarboxylic acid-based polymer constituting the surface treatment film layer, an existing polycarboxylic acid-based polymer can be used, and the polycarboxylic acid-based polymer is two or more in the molecule. It is a generic term for polymers having a carboxyl group. Examples of such polycarboxylic acid-based polymers include (co) polymers of ethylenically unsaturated carboxylic acids, copolymers of ethylenically unsaturated carboxylic acids and other ethylenically unsaturated monomers, Examples include acidic polysaccharides having a carboxyl group in the molecule, such as alginic acid, carboxymethylcellulose, and pectin. One of these polycarboxylic acid polymers may be used alone, or two or more thereof may be used as a mixture.
Examples of such ethylenically unsaturated carboxylic acids include acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid and the like. Further, as the ethylenically unsaturated monomers copolymerizable with these ethylenically unsaturated carboxylic acids, for example, ethylene, α-olefins such as propylene, carboxylic acid vinyl esters such as vinyl acetate, alkyl acrylate, Examples include ethylenically unsaturated carboxylic esters such as alkyl methacrylate and alkyl itaconate, vinyl chloride, vinylidene chloride, styrene, acrylamides, acrylonitrile and the like. When the polycarboxylic acid polymer is a copolymer of an ethylenically unsaturated carboxylic acid and a carboxylic acid vinyl ester such as vinyl acetate, the saponification further converts the carboxylic acid vinyl ester portion into vinyl alcohol. Can be used.

Among such polycarboxylic acid polymers, from the viewpoint of the retort resistance described above, the polycarboxylic acid polymer is at least one polymer selected from acrylic acid, methacrylic acid, itaconic acid, and maleic acid. It is preferable to use a polymer containing a structural unit derived from a hydrophilic monomer, or a mixture of the polymers. The polymer may be a homopolymer or a copolymer. In the polymer, constituent units derived from at least one polymerizable monomer selected from among the acrylic acid, maleic acid, methacrylic acid, and itaconic acid are preferably 60 mol% or more, more preferably 80 mol%. As described above, most preferably 100 mol%, that is, a polymer in which the polycarboxylic acid-based polymer comprises only at least one polymerizable monomer selected from the above-mentioned acrylic acid, maleic acid, methacrylic acid, and itaconic acid (However, all the structural units are set to 100 mol%.) When a structural unit other than the above structural unit is included, the other structural unit may be, for example, the above-mentioned ethylenically unsaturated carboxylic acid. And copolymerizable ethylenically unsaturated monomers.
When the polycarboxylic acid-based polymer is a polymer composed of at least one polymerizable monomer selected from the above-mentioned acrylic acid, maleic acid, methacrylic acid, and itaconic acid, the polymerizable monomer A homopolymer, a copolymer, or a mixture thereof can be used. More preferably, polyacrylic acid, polymethacrylic acid, polyitaconic acid, polymaleic acid, and mixtures thereof can be used.

  The weight average molecular weight (Mw) of the polycarboxylic acid-based polymer is not particularly limited, but is 3,000 to 1,000,000, preferably 10,000 to 1,000,000, and more preferably 10,000 to 500, 000 is desirable. If the weight average molecular weight is smaller than the above range, when subjected to a high temperature environment such as a high temperature, high pressure and high humidity environment such as retort sterilization treatment or a heat setting step after can body molding, In some cases, the surface treatment film layer may undergo cohesive failure, and the retort resistance and suitability for can production may be poor. On the other hand, when the weight average molecular weight is larger than the above range, the stability of the surface treatment liquid may be reduced, gelling may occur with time, and productivity may be difficult.

(Zirconium compound)
In the present invention, examples of the zirconium compound constituting the surface treatment film layer include zirconium oxide, hexafluorozirconic acid (H ₂ ZrF ₆ ), potassium hexafluorozirconium (K ₂ ZrF ₆ ), and hexafluorozirconium ammonium ((NH ₄ ) ₂ ZrF ₆ ), ammonium zirconium carbonate ((NH ₄ ) ₂ ZrO (CO ₃ ) ₂ ), zirconium oxynitrate (ZrO (NO ₃ ) ₂ ), zirconium oxyacetate (ZrO (C ₂ H ₃ O ₂ ) ₂ ) , zirconium oxychloride (ZrOCl _2), oxy zirconium sulfate (ZrOSO _4), oxy zirconium carbonate (ZrOCO _3), oxy zirconium octylate _{(ZrO (C 8 H 15 O} 2) 2), hydroxide oxyzirconium (ZrO (OH _2), hydroxide zirconium oxychloride (ZrO (OH) Cl), potassium zirconium carbonate _{(K 2 (ZrO (CO 3} ) 2)), zirconium phosphate, zirconium lactate, zirconium acetylacetonate [Zr (OC (= CH ₂ ) CH ₂ COCH ₃ ) ₄ ]. Among the above zirconium compounds, those containing no fluorine component are preferable from the viewpoint of environmental load, and oxyzirconium salts are particularly preferable. Here, the “oxyzirconium salt” refers to a salt containing a positive divalent group represented by ZrO (called zirconyl). Examples of the oxyzirconium salt include ammonium zirconium carbonate ((NH ₄ ) ₂ ZrO (CO ₃ ) ₂ ), zirconium oxynitrate (ZrO (NO ₃ ) ₂ ), and zirconium oxyacetate (ZrO (C ₂ H ₃ O ₂ ) ₂ ). , Zirconium oxychloride (ZrOCl ₂ ), zirconium oxysulfate (ZrOSO ₄ ), zirconium oxycarbonate (ZrOCO ₃ ), ammonium zirconium carbonate ((NH ₄ ) ₂ ZrO (CO ₃ ) ₂ ), oxyzirconium hydroxide (ZrO (OH) ₂ ), zirconium hydroxide oxychloride (ZrO (OH) Cl), potassium zirconium carbonate (K ₂ (ZrO (CO ₃ ) ₂ )) and the like, and among the above-mentioned, water-soluble oxyzirconium salts are preferable, and in particular, Stability in processing solution, viewpoint of retort resistance Et al., Can be suitably used zirconium ammonium carbonate as a precursor.
When the above-mentioned water-soluble oxyzirconium salt (zirconium ammonium carbonate) is used as the zirconium compound, the oxyzirconium salt is oxidized with respect to 100 parts by mass of the polycarboxylic acid polymer in the surface treatment film layer. zirconium (ZrO ₂₎ 5 to 90 parts by mass in terms of, preferably preferred that are contained in 25 to 70 parts by weight, more preferably 30 to 65 parts by weight, particularly preferably from 40 to 65 parts by weight .

(Colloidal silica)
In the present invention, the colloidal silica constituting the surface treatment film layer is not limited to this, but may be spherical such as LUDOX (WR Grace), Snowtex N, and Snowtex UP (Nissan Chemical Industries). Silica can be mentioned. The colloidal silica preferably has a particle size of 2 to 80 nm, particularly 4 to 30 nm. Particles smaller than the above range are generally difficult to obtain, while particles larger than the above range make it difficult to uniformly distribute colloidal silica in the surface-treated coating layer, and it is difficult to obtain the above-mentioned effects.

The surface treatment film layer in the present invention may be a metal compound other than a zirconium compound (for example, a monovalent alkali metal compound such as sodium or potassium, or a polyvalent metal compound such as zinc, calcium, or aluminum) as long as the object of the present invention is not impaired. ) Can be used as a mixture or as contained.
In addition, within the range not impairing the object of the present invention, water-soluble materials such as polyvinyl alcohol, ethylene-vinyl alcohol copolymer, polyvinyl pyrrolidone, polyvinyl ethyl ether, polyacrylamide, acrylamide-based compounds, polyethyleneimine, starch, gum arabic, methylcellulose and the like. A polymer derived from an aqueous dispersion (emulsion) such as a polymer, polyvinyl acetate, an ethylene / vinyl acetate copolymer, a polyester resin, or a polyurethane resin may be contained.

(Calculation of peak height ratio (β / α))
Here, a method for calculating the peak height ratio (β / α) of the surface treatment film layer of the organic resin-coated seamless can by the infrared absorption spectrum measurement described above will be described below. First, a can body side wall portion was cut out from an organic resin-coated seamless can as a measurement sample, and after removing the organic resin coating layer by a predetermined method, the infrared absorption spectrum of the surface treatment film layer on the measurement sample surface was determined to be 4000 to 700 cm. ^After measuring in the wave number range of ^-1 and subtracting the absorption peaks derived from water vapor and carbon dioxide from the infrared absorption spectrum of the obtained surface treatment film layer, as illustrated in FIG. 1, 1660 to 1760 cm of the infrared absorption spectrum to give maximum absorption peak height in the wavenumber range of ^-1 and (alpha) maximum absorption peak height in the wavenumber range of 1490～1659Cm ^-1 a (beta), the peak height ratio of using them (beta / α) is calculated. Here, the maximum absorption peak height (α) in the wave number range of 1660 to 1760 cm ⁻¹ and the maximum absorption peak height (β) in the wave number range of 1490 to 1659 cm ⁻¹ of the infrared absorption spectrum are defined as follows. I do.

Maximum peak height (alpha): the base within the wavenumber range of 1800～2000Cm ^-1, and that the absorbance is the lowest, in the wavenumber range of 1000 to 1200 ^-1, the straight line connecting the points at which the absorbance is the lowest As a line, a straight line is drawn perpendicularly to the horizontal axis (wave number) from the top of the maximum absorption peak within the wave number range of 1660 to 1760 cm ⁻¹ , and the absorbance at the intersection of the straight line and the baseline and the absorbance at the top of the maximum absorption peak. Is the maximum peak height (α).
Maximum peak height (beta): base within the wavenumber range of 1800～2000Cm ^-1, and that the absorbance is the lowest, in the wavenumber range of 1000 to 1200 ^-1, the straight line connecting the points at which the absorbance is the lowest As a line, a straight line is drawn perpendicularly to the horizontal axis (wave number) from the peak of the maximum absorption peak in the wave number range of 1490 to 1659 cm ⁻¹ , and the absorbance at the intersection of the straight line and the baseline and the absorbance at the peak of the maximum absorption peak are determined. The difference is defined as the maximum peak height (β).

Further, the polycarboxylic acid-based polymer used in the present invention is a copolymer of ethylenically unsaturated carboxylic acid and other ethylenically unsaturated carboxylic acid esters such as alkyl acrylate or alkyl methacrylate or ethylenically unsaturated carboxylic acid. A mixture of a polymer of a polymer and an unsaturated carboxylic acid ester, or a copolymer of an ethylenically unsaturated carboxylic acid and a vinyl carboxylate, or a mixture of a polymer of an ethylenically unsaturated carboxylic acid and a polymer of a vinyl carboxylate In the case of, the C ＝ O stretching vibration attributable to the ester bond of the carboxylic acid ester (—COO—R: R is an alkyl group) has an absorption peak having an absorption maximum within a wavenumber range of 1730 cm ^{−1 to} 1760 cm ^−1. give. Therefore, strictly speaking, the maximum absorption peak in the wave number range of 1660 to 1760 cm ^-1 of the infrared absorption spectrum of the copolymer or the mixture includes a carboxyl group (-COOH) and an ester bond (-COO-R). In some cases, the peak height ratio (β / α) calculated by the above-described procedure is changed to free carboxyl that does not form a metal salt with zirconium. It is used as it is as a scale representing the quantitative ratio of the carboxyl group (—COO ⁻ ) forming a metal salt with the group (—COOH) and zirconium. Furthermore, within the range not impairing the object of the present invention, similarly, when the surface-treated film layer contains a compound having an ester bond or a polymer, the peak height ratio (β / α) is used as it is as a scale representing the quantitative ratio of a free carboxyl group (—COOH) not forming a metal salt with zirconium and a carboxyl group (—COO ⁻ ) forming a metal salt with zirconium.

On the other hand, when the surface treatment film layer contains a metal other than zirconium such as an alkali metal such as sodium or potassium or a polyvalent metal such as zinc or calcium, as long as the object of the present invention is not impaired (for example, In the case where a metal salt other than zirconium of a polycarboxylic acid polymer is used, for example, in the form of a mixture or contained as it is), C belonging to a metal salt of a carboxyl group and a metal other than zirconium (—COO ⁻ ) The = O stretching vibration gives an absorption peak having an absorption maximum near 1560 cm ^-1 within the wave number range of 1490 to 1659 cm ^-1 . Therefore, strictly speaking, in the peak of the infrared absorption spectrum, the CＯO stretching vibration derived from a metal salt of a carboxyl group and zirconium and the C ＝ O stretching vibration partially derived from a metal salt of a carboxyl group and a metal other than zirconium. In this case as well, the peak height ratio (β / α) calculated according to the above-described procedure is changed to a free carboxyl group (—COOH) that does not form a metal salt with zirconium, a zirconium and a metal salt. It is used as it is as a scale representing the quantitative ratio of the formed carboxyl group (—COO ⁻ ).

  As a method for measuring the infrared absorption spectrum of the surface-treated metal plate surface, a high-sensitivity reflection method (reflection absorption method) capable of measuring the infrared absorption spectrum of a thin film formed mainly on a metal substrate with high sensitivity ) Are preferred. Further, it is preferable to use a polarizer for the measurement. By using a polarizer, it is possible to perform measurement with higher sensitivity by detecting only parallel polarized light (P-polarized light). However, since the use of a polarizer reduces the amount of infrared light that can be used for measurement and increases noise, a semiconductor-type cadmium mercury telluride (MCT) detector is preferable as the detector used for measurement. is there. It is preferable to use a gold vapor deposition mirror as a reference substrate used for measurement.

(Surface treatment liquid)
The surface treatment solution for forming the surface treatment film layer of the present invention can be formed from a surface treatment solution containing a polycarboxylic acid-based polymer, a zirconium compound, an aqueous medium, and if necessary, colloidal silica.
In such a surface treatment liquid, the zirconium compound is 3 to 67 parts by mass, preferably 18 to 52 parts by mass, more preferably 22 to 32 parts by mass in terms of zirconium, based on 100 parts by mass of the solid content of the polycarboxylic acid polymer. It is preferable that the compound is contained in an amount of from 48 to 48 parts by mass, particularly preferably from 29 to 48 parts by mass. (In the case of oxyzirconium salt wherein the zirconium compound described above, the polycarboxylic acid polymer per 100 parts by weight, oxy zirconium salt is zirconium oxide (ZrO ₂₎ 5 to 90 parts by mass in terms of, preferably 25 to 70 mass Parts, more preferably 30 to 65 parts by mass, particularly preferably 40 to 65 parts by mass.)
Further, when colloidal silica is blended in the surface treatment liquid, the colloidal silica is 10 to 200 parts by mass, particularly 50 to 200 parts by mass in terms of solid content (silicon dioxide; SiO ₂ ) per 100 parts by mass of the polycarboxylic acid polymer. It is preferred to mix in parts. When the amount of colloidal silica is smaller than the above range, sufficient improvement in heat resistance cannot be expected.On the other hand, even when the amount of colloidal silica is larger than the above range, no further improvement in heat resistance can be obtained. Retort resistance may be reduced.

  As the aqueous medium, distilled water, ion-exchanged water, water such as pure water can be used, and like known aqueous compositions, alcohols, polyhydric alcohols, containing organic solvents such as derivatives thereof. Can be. When such a cosolvent is used, it can be contained in an amount of 5 to 30% by weight based on water. By containing the solvent in the above range, the film forming performance is improved. Examples of such an organic solvent 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, and dipropylene glycol monomethyl ether. Butyl ether, tripropylene glycol monomethyl ether, 3-methyl 3-methoxybutanol and the like.

  The surface treatment solution may further contain, if necessary, additives such as a stabilizer, an antioxidant, a surface conditioner, and an antifoaming agent used in a general metal surface treatment solution.

(Method of 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, as a surface cleaning for removing rolling oil, rust-preventive oil, etc., the metal plate is subjected to a degreasing treatment, followed by washing with water or surface adjustment. Then, the above-mentioned surface treatment liquid is applied on a metal plate, and heated and dried to form a surface treatment film layer.

  The degreasing treatment is not particularly limited, and examples thereof include alkali cleaning and acid cleaning conventionally used for degreasing a metal plate such as aluminum or an aluminum alloy. In the present invention, from the viewpoint of adhesion between the surface treatment 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.

  The alkaline cleaner is not particularly limited, and for example, those used for ordinary alkaline cleaning can be used, and examples thereof include “Surf Cleaner 420N-2” manufactured by Nippon Paint Co., Ltd. The acidic cleaner is not particularly limited, and examples thereof include an aqueous solution of an inorganic acid such as sulfuric acid, nitric acid, and hydrochloric acid. After performing the above degreasing treatment, in order to remove the degreasing agent remaining on the metal plate surface, after performing a water washing treatment, the moisture on the metal plate surface is removed by a method such as air blowing or hot air drying. .

  The surface treatment liquid is applied by a roll coating method, a spray method, an immersion method, a brush coating method, and a spray drawing method (after applying the surface treatment liquid onto a metal plate by spraying, the liquid film is squeezed out with a roll or air and dried). Can be applied to the metal plate by a conventionally known method such as a immersion drawing method (a metal plate is immersed in a surface treatment liquid, the liquid film is strongly squeezed out with a roll or air, and dried). The drying condition is 50 to 300 ° C. for 5 seconds to 5 minutes, preferably 50 to 250 ° C. for 10 seconds to 2 minutes.

(Metal plate)
The metal plate used in the present invention is not particularly limited, but various steel plates and aluminum plates are used. As the steel sheet, a cold-rolled steel sheet may be annealed and then subjected to secondary cold rolling, and a clad steel sheet or the like may be used. In addition, as the aluminum plate, an aluminum plate made of an aluminum alloy can be used in addition to so-called pure aluminum. In the present invention, an aluminum plate made of an aluminum alloy can be particularly preferably used.
The original thickness of the metal plate is not particularly limited, and varies depending on the type of the metal, the use or the size of the container, but the metal plate generally preferably has a thickness of 0.10 to 0.50 mm. In the case of (1), 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.

In the present invention, a metal plate that has been subjected to a conventionally known surface treatment such as chemical conversion treatment or plating may be used as the metal plate.
As the surface treatment described above, when a steel plate is used as a metal plate, zinc plating, tin plating, nickel plating, aluminum plating, electrolytic chromic acid treatment, chromic acid treatment, phosphoric acid treatment, non-chromium using aluminum or zirconium One or more surface treatments such as treatments can be given. When an aluminum plate is used as the metal plate, an acrylic resin, a phenol resin, and the like are used for the inorganic compound forming treatment such as a phosphoric acid chromate treatment, a zirconium phosphate treatment, a zirconium treatment, and a phosphoric acid treatment. And an organic-inorganic composite molding treatment in which an organic component such as tannic acid or a water-soluble resin is combined.

(Organic resin coating layer)
In the organic resin-coated seamless can of the present invention, the organic resin constituting the organic resin coating layer applied on the surface treatment film layer is not particularly limited, for example, crystalline polypropylene, crystalline propylene-ethylene copolymer , Crystalline polybutene-1, crystalline poly4-methylpentene-1, low-, medium-, or high-density polyethylene, ethylene-vinyl acetate copolymer (EVA), ethylene-ethyl acrylate copolymer (EEA) , Polyolefins such as ion-crosslinked olefin copolymers (ionomers); aromatic vinyl copolymers such as polystyrene and styrene-butadiene copolymer; halogenated vinyl polymers such as polyvinyl chloride and vinylidene chloride resin; acrylonitrile-styrene Copolymer, acrylonitrile-styrene-butadiene copolymer Polyamides such as nylon 6, nylon 66, para- or meta-xylylene adipamide; Polyesters such as polyethylene terephthalate (PET) and polytetramethylene terephthalate; Various polycarbonates; Thermoplastics such as polyacetals such as polyoxymethylene Resins, and a thermoplastic resin film made of these thermoplastic resins can be used as the organic resin coating layer.
As the organic resin coating layer used in the present invention, a thermoplastic resin film composed of a thermoplastic resin is suitable, and in particular, a polyester resin film can be suitably used.

The polyester resin constituting the polyester resin film may be a homopolyethylene terephthalate resin, or 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. It may be a copolymerized polyester resin composed mainly of polyethylene terephthalate or a blend resin of a homopolyethylene terephthalate resin and the above-mentioned copolymerized polyester resin composed mainly of polyethylene terephthalate, which is contained in an amount of 30 mol% or less based on the alcohol component.
Acid components other than the 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, dodecandioic acid, dimer acid, trimellitic acid, and pyromellitic acid.
Examples of the alcohol component other than ethylene glycol include propylene glycol, 1,4-butanediol, neopentyl glycol, 1,6-hexylene glycol, diethylene glycol, triethylene glycol, cyclohexane dimethanol, and an ethylene oxide adduct of bisphenol A, Glycol components such as trimethylolpropane and pentaerythritol can be mentioned.

  Further, a homopolyethylene terephthalate resin and / or a copolymerized polyester resin mainly composed of polyethylene terephthalate and other crystalline polyester resins, for example, a copolymerized polyester resin mainly composed of homopolybutylene terephthalate resin and / or polybutylene terephthalate resin, Alternatively, a resin blended with a homopolyethylene naphthalate resin and / or a copolymerized polyester resin mainly composed of a polyethylene naphthalate resin may be used. In that case, the crystalline polyester resin other than the homopolyethylene terephthalate resin and the copolymerized polyester resin mainly composed of the polyethylene terephthalate resin is compared with the homopolyethylene terephthalate resin and / or the copolymerized polyester resin mainly composed of the polyethylene terephthalate resin. Is preferably 5 to 50 wt%.

  Among the above polyester resins, in particular, polyethylene terephthalate resin comprising ethylene terephthalate unit, 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 any one of a polybutylene terephthalate resin blend resin, a polyethylene terephthalate / polyethylene isophthalate copolymer resin and a polybutylene terephthalate resin blend resin, particularly, a polyethylene terephthalate / polyethylene isophthalate copolymer resin, a polyethylene terephthalate / polyethylene resin. 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 (based on an acid component). As the blend resin of the polyethylene terephthalate / polyethylene isophthalate copolymer resin and the polybutylene terephthalate resin, a resin obtained by blending a polyethylene terephthalate / polyethylene isophthalate copolymer resin with a polybutylene terephthalate resin in a range of 10 to 50 wt% is used. preferable.

  The polyester resin used as the organic resin coating layer should have a molecular weight in the range of forming a film, and has an intrinsic viscosity [η] of 0.5 or more, particularly 0. 0. It is preferably in the range of 52 to 0.70 from the viewpoint of barrier properties against corrosive components and mechanical properties, and the glass transition point is preferably 50C or more, particularly preferably 60C to 80C.

A thermoplastic resin film such as a polyester resin film can be blended with a known film compounding agent, a lubricant, an antiblocking agent, a pigment, various antistatic agents, an antioxidant, and the like by a known formulation.
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 composed of a thermoplastic resin film can also have a two-layer structure.When a polyester resin is used as the thermoplastic resin, as a lower layer, mainly ethylene terephthalate units are used, and isophthalic acid, naphthalenedicarboxylic acid, etc. At least one kind is contained in an amount of 1 to 30 mol%, and it is possible to form from a polyester resin having a larger amount than the acid component in the polyester resin to be an upper layer from the viewpoint of processing adhesion, corrosion resistance and the like. Particularly preferred.

  The organic resin coating layer made of a thermoplastic resin film is formed on the surface treatment film layer via a conventionally known adhesive primer layer such as an epoxy / phenol resin or polyester / phenol resin. Is also good. The adhesive primer layer exhibits excellent adhesiveness to both the surface treatment film layer and the organic resin coating layer. The epoxy / phenolic resin-based adhesive primer may be formed from a paint containing an epoxy resin and a phenolic resin in a weight ratio of 50:50 to 99: 1, particularly 60:40 to 95: 5. It is preferable from the viewpoint of adhesion and corrosion resistance. The polyester / phenolic resin-based adhesive primer may be formed from a paint containing a polyester resin and a phenolic resin in a weight ratio of 50:50 to 99: 1, particularly 60:40 to 95: 5. It is preferable from the viewpoint of adhesion and corrosion resistance. Generally, the above-mentioned adhesive primer layer is preferably provided with a thickness of 0.1 to 10 μm. The adhesive primer layer may be provided in advance on a surface-treated coating layer on a surface-treated metal plate, or may be provided on an organic resin coating layer such as the above polyester resin film.

(Method of forming organic resin coating layer on surface-treated metal plate)
As a method of 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 previously forming a thermoplastic resin film by a conventionally known method, A method of coating the treated metal sheet by a thermal bonding method, an extrusion laminating method of extruding a heated and melted thermoplastic resin into a film shape by using an extruder, and directly coating the surface of the surface-treated metal sheet are preferable. In the case of coating after forming the thermoplastic resin film, the film may be stretched, but is preferably an unstretched film from the viewpoint of moldability and dent resistance.

(Can body and its manufacturing method)
The organic resin-coated seamless can of the present invention can be manufactured from an organic resin-coated surface-treated metal plate by a conventionally known molding method.
The organic resin-coated surface-treated metal sheet used in the present invention has draw processing, drawing / deep drawing processing, drawing / ironing processing, drawing / bending and stretching processing because the organic resin coating layer has excellent processing adhesion. -A seamless can formed by severe processing such as ironing can be formed without causing delamination or peeling of the resin coating on the flange forming portion.
The side wall of the seamless can is stretched by drawing and redrawing of the organic resin-coated surface-treated metal sheet or further ironing, and 20 to 95%, particularly 25 to 85% of the original thickness of the organic resin-coated surface-treated metal sheet. It is preferable that the thickness is reduced.
The obtained seamless can is subjected to at least one stage of heat treatment to remove residual distortion of the film caused by processing, to volatilize the lubricant used for processing from the surface, and to dry and harden the printing ink printed on the surface. The container after the heat treatment is quenched or allowed to cool, and then subjected to a single-stage or multi-stage neck-in process, if necessary, and subjected to a flange process to obtain a can for winding.

  FIG. 2 is an enlarged cross-sectional view of an example of the organic resin-coated seamless can of the present invention and a cross-sectional structure of the can body portion. An organic resin-coated surface-treated metal substrate 1 composed of the treated surface-treated coating layers 3a and 3b and the organic resin-coated layers 4a and 4b. In the specific example shown in FIG. 2, the organic resin coating layers 4a and 4b are formed on both the inner and outer surfaces of the container of the metal substrate 2 via the surface treatment coating layers 3a and 3b. In a seamless can, the surface treatment film layer 3 and the organic resin coating layer 4 only need to be formed on at least one surface of the can body, and the inner surface or the outer surface of the can body has a different surface treatment film layer and organic resin coating layer. Layers can also be formed.

  Hereinafter, the present invention will be described in detail with reference to specific examples, but the present invention is not limited to the following examples. In the following, “parts” means “parts by mass”.

[Examples 1 to 24, Comparative Examples 1 to 3]
(Preparation of surface treatment liquid)
The polycarboxylic acid polymer was dissolved in ion-exchanged water to obtain a 2% by mass aqueous solution of the polycarboxylic acid polymer. An aqueous solution of a zirconium compound was gradually added to the obtained aqueous solution of a polycarboxylic acid-based polymer while stirring at room temperature so as to have a predetermined solid content ratio. The aqueous solution of the zirconium compound was adjusted to a predetermined solid content concentration with ion-exchanged water as needed, and then added to the aqueous solution of the polycarboxylic acid polymer. When colloidal silica is further compounded, an aqueous dispersion of colloidal silica is added to an aqueous solution containing a polycarboxylic acid polymer and a zirconium compound while stirring at room temperature so as to have a predetermined solid content ratio. did. Then, ion-exchanged water was added with stirring to prepare a surface treatment liquid by adjusting the solid content concentration of the polycarboxylic acid-based polymer in the aqueous solution to be 0.5 to 1% by mass.

Examples of the polycarboxylic acid polymer include polyacrylic acid (manufactured by Toagosei Co., Ltd., “Julima AC-10LP, Mw = 25,000”: described as “PAA1” in the table, and “Julima 10LHP, Mw = 250,000”: Table In the table, “PAA2”, “Julima AC-10P, Mw = 5,000”: described in the table as “PAA3”, polymethacrylic acid (“Polymethacrylic acid, Mw = 100,000” manufactured by Wako Pure Chemical Industries, Ltd.): In the table, "PMA" was used, and polyitaconic acid ("PIA-728, Mw = 3,000" manufactured by Iwata Chemical Industry Co., Ltd .: described as "PIA" in the table) was used.
The zirconium compound, zirconium ammonium carbonate (manufactured by Daiichi Kigenso Kagaku Co. "ZIRCOSOL AC-7, ZrO ₂ in terms of content = 13 wt%") was used. Examples of colloidal silica include W.I. R. “LUDOX AS-30, average particle size = 20 nm, content in terms of SiO ₂ = 30% by mass” manufactured by Grace Co., Ltd. was used. For the used polycarboxylic acid-based polymer and the solid content of the polycarboxylic acid-based polymer in the surface treatment solution, 100 parts by weight of the zirconium compound in terms of zirconium oxide (ZrO ₂ ) and zirconium-converted solids, and Table 1 shows the solid content of colloidal silica in terms of silicon dioxide (SiO ₂ ).

(Production of surface treated metal plate)
An aluminum plate (plate thickness 0.28 mm, 3104 alloy plate, A4 size) was used as the metal plate. First, alkali washing was performed by immersing in a 2% aqueous solution (60 ° C.) of an alkaline cleaner “Surf Cleaner 420N-2” (trade name) manufactured by Nippon Paint Co. for 6 seconds. After the alkali washing, the substrate was washed with water, then immersed in a 2% aqueous sulfuric acid solution (60 ° C.) for 6 seconds to perform acid washing, washed with water, and dried. The surface treatment liquid described above was applied to both sides of the obtained metal plate on the inner surface side and the outer surface side of the can, and dried in an oven set at 150 ° C. for 60 seconds to prepare a surface-treated metal plate. The same surface treatment liquid was applied under the same conditions on the inner surface of the metal plate and the outer surface of the can to form a similar surface treatment film layer.

(Production of metal sheet coated with organic resin)
The obtained surface-treated metal plate is previously heated to a plate temperature of 250 ° C., and a polyester resin film as an organic resin coating layer is thermocompression-bonded to both surfaces of the surface-treated metal plate via a laminating roll, and then immediately cooled with water. Thus, a surface-treated metal plate coated with an organic resin was obtained. As the polyester resin film on the inner surface side of the can, a polyethylene terephthalate / polyethylene isophthalate copolymer resin film having a thickness of 12 μm was used. A 12 μm thick polyethylene terephthalate / polyethylene isophthalate copolymer resin film (PET / IA) or a 12 μm thick polyethylene terephthalate / polyethylene isophthalate copolymer resin and a polybutylene terephthalate resin as an organic resin coating layer on the outer surface of the can A film (PET / IA.PBT) was used. Table 1 shows the types of the organic resin coating layer on the outer surface of the can in each example.

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

(Content measurement)
The content per unit area (mg / m ² ) of carbon derived from the polycarboxylic acid polymer, zirconium derived from the zirconium compound, and silicon derived from colloidal silica in the surface treatment film layer of the organic resin-coated seamless can is as follows: After preparing a measurement sample by the following procedure, measurement was performed using a fluorescent X-ray analyzer. First, after preparing a seamless can as described in the section "Production of a seamless can", a sample obtained by cutting out the center of the bottom of the can of the obtained seamless can into a size of 2 cm x 2 cm was used as a sample. The sample was immersed in 300 mL of 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) at normal temperature for 1 hour to dissolve and remove the organic resin coating layer (polyester resin film). A sample was taken out of the HFIP, and HFIP attached to the sample was removed to obtain a sample for measurement. At the time of the measurement, first, a plurality of standard samples having different contents of carbon or zirconium or silicon were measured, and a calibration curve of strength-content was prepared from the strength at this time. Under the same conditions, a measurement sample obtained from the organic resin seamless can in each example was also measured, and the obtained measurement intensity was converted into the content based on the calibration curve, whereby the organic resin-coated seamless can was canned. The contents of carbon, zirconium and silicon in the surface treatment film layer located at the bottom were measured. Table 1 shows the measurement results of the contents of carbon (C), zirconium (Zr), and silicon (Si).
Equipment used: Rigaku ZSX100e
Measurement condition: Measurement diameter 10mm
X-ray output: 50kV-70mA

(Measurement of peak height ratio (β / α))
The peak height ratio (β / α) of the surface treatment film layer in the obtained organic resin-coated seamless can was calculated by infrared absorption spectrum measurement after preparing a measurement sample according to the following procedure. First, after preparing a seamless can as described in the section "Production of a seamless can", a can body side wall portion of the obtained seamless can was cut out to a size of 8 cm x 4 cm as a sample, and the sample was prepared. Was immersed in 300 mL of 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) at room temperature for 1 hour to dissolve and remove the organic resin coating layer (polyester resin film). A sample was taken out of the HFIP, and HFIP attached to the sample was removed to obtain a sample for measurement. Next, the infrared absorption spectrum of the surface treatment film layer on the surface of the measurement sample was measured, and from the infrared absorption spectrum of the obtained surface treatment film layer, an infrared absorption spectrum obtained by subtracting the absorption peaks of water vapor and carbon dioxide gas was used. The peak height ratio (β / α) of the surface-treated coating layer was calculated by the method described in the section “Calculation of peak height ratio (β / α)”.
Equipment used: Digilab FTS7000 series
Detector used: MCT detector Accessories used: Advanced Grazing Angle (AGA) manufactured by PIKE
Measuring method: High sensitivity reflection method (incident angle: 80 ° C, number of integration: 100 times, reference substrate: gold vapor deposition mirror, only parallel polarized light using polarizer)
Measurement wave number region: 4000 to 700 cm ^-1

(Comparative Example 4)
As the metal plate, using a surface-treated aluminum plate (plate thickness 0.28 mm, 3104 alloy plate, chromium content in the surface-treated coating layer: 20 mg / m ² ) subjected to phosphoric acid chromate treatment (chemical conversion treatment), Preparation of Organic-Resin-Coated Surface-Treatment Metal Sheet ", an organic-resin-coated surface-treated metal plate was prepared, and a seamless can was prepared as described in the above-mentioned section" Preparation of Seamless Can ".

[Evaluation of peelability of flange during heat treatment (evaluation of suitability for can-making)]
As described in the section of “Production of Seamless Can” above, the can body was trimmed until the can body was trimmed, and then heated at 201 ° C. for 75 seconds and then at 210 ° C. for 80 seconds. After performing the heat treatment for 2 seconds, the opening end (flange forming portion) of the can was observed with a microscope, and the degree of peeling of the organic resin coating layer from the opening end of the can was evaluated. Table 1 shows the evaluation results.
◎: The maximum length of the peeled portion is less than 0.05 mm. ○: The maximum length of the peeled portion is 0.05 mm or more and less than 0.1 mm. Δ: The maximum length of the peeled portion is 0.1 mm or more and less than 0.2 mm. ×: The maximum length of the peeled portion is 0.2 mm or more.

[Evaluation of flange releasability during retort]
The evaluation of the releasability of the flange portion at the time of retort was performed by the following method after producing a seamless can as described in the section of “Production of Seamless Can”. First, the obtained seamless can is placed upright (the bottom of the can is on the lower side) in a retort pot, and subjected to pressure heat sterilization treatment at 125 ° C. for 30 minutes by steam in a sealed retort pot. did. After cooling to room temperature after the pressurized heat sterilization treatment, the seamless can was taken out of the retort kettle, and the state of peeling of the organic resin coating layer on the inner and outer flange portions was observed and evaluated. Table 1 shows the evaluation results.
◎: No peeling was observed over the entire circumference. ：: Partial peeling was observed, but the length of the peeled portion was less than 5% of the entire circumference of the can. Δ: Partial peeling was observed, but the peeling was observed. The length of the portion is 5% or more and less than 10% of the entire circumference of the can. ×: The length of the peeled portion is 10% or more in the entire circumference direction.

[Appearance evaluation of can body side wall during retort]
The evaluation of the outer appearance of the side wall of the can body at the time of retort was performed by the following method after producing a seamless can as described in the section of “Production of Seamless Can”. First, 500 g of water was filled in the obtained seamless can, and the lid was tightly wound according to a conventional method to obtain a filled pack can. The obtained filled pack can is immersed in water and placed in a stainless steel case in a state where the can body side wall on the outer surface of the can is sufficiently wet, so that the filled pack can is turned sideways (the can body side wall is on the lower side). And the stainless steel case is left standing in a retort pot, with the side wall of the can body partially in contact with water, and pressurized and heated at 130 ° C for 5 minutes with steam in a sealed retort pot with steam. Processing was performed. After the pressurized heat sterilization treatment, after cooling to room temperature, the filled pack can is taken out of the retort pot, and the presence or absence of floating of the organic resin coating layer and blisters (blisters) on the side wall of the can body on the outer surface of the can is visually observed. evaluated. Table 1 shows the evaluation results.
◎: Blister generation was not observed at all ○: Blister generation was hardly recognized △: Blister generation was partially observed ×: Blister generation was remarkable

  The organic resin-coated seamless can of the present invention has excellent suitability for can-making and the organic resin coating layer peels off at the flange even when subjected to a high-temperature, high-pressure, high-humidity environment such as retort sterilization. In addition, even if the retort treatment is performed under more severe conditions, such as when the can body on the outer surface of the can is sterilized under pressure and heat by steam while in contact with water, an outer surface defect such as a blister can occur. Since excellent retort resistance that does not occur can be exhibited, it can be suitably used particularly as a metal can container for coffee beverages or the like that requires retort sterilization after filling the contents.

  1 surface treated metal substrate coated with organic resin, 2 metal substrate, 3 surface treated film layer, 4 organic resin coated layer, 10 organic resin coated seamless can.

Claims (10)

An organic resin-coated seamless can having a surface treatment film layer and an organic resin coating layer on the surface treatment film layer on at least one surface of the metal can, wherein the surface treatment film layer contains a polycarboxylic acid polymer and a zirconium compound. The maximum absorption peak height (α) in the wave number range of 1660 to 1760 cm ⁻¹ and the maximum ^{value in} the wave number range of 1490 to 1659 cm ⁻¹ when measuring the infrared absorption spectrum of the surface-treated coating layer. peak height ratio of the absorption peak height (β) (β / α) is Ri der 0.10 to 2.40, an organic resin-coated seamless can wherein said zirconium compound does not contain fluorine.   The polycarboxylic acid polymer is a polymer, a copolymer, or a mixture thereof obtained by polymerization of at least one polymerizable monomer selected from acrylic acid, methacrylic acid, itaconic acid, and maleic acid. The organic resin-coated seamless can according to claim 1, wherein:   The organic resin-coated seamless can according to claim 1 or 2, wherein the zirconium compound is a zirconium compound derived from an oxyzirconium salt.   The organic resin-coated seamless can according to claim 3, wherein the oxyzirconium salt is ammonium zirconium carbonate. The content of the polycarboxylic acid-based polymer in the surface treatment film layer is ² to 100 mg / m ² in terms of carbon, and the content of the zirconium compound is 1 to 80 mg / m ² in terms of zirconium. The organic resin-coated seamless can according to any one of claims 1 to 4, characterized in that:   The said surface-treated coating layer contains a zirconium compound in an amount of 3 to 67 parts by mass in terms of zirconium, based on 100 parts by mass of the solid content of the polycarboxylic acid polymer. The organic resin-coated seamless can according to any one of the above.   The organic resin-coated seamless can according to any one of claims 1 to 6, wherein the surface treatment film layer further contains colloidal silica. An organic resin-coated seamless can according to claim 7, wherein the content of the colloidal silica in the surface treatment film layer is 1 to 200 mg / m ² of silicon conversion.   The said organic resin coating layer is a polyester resin film, The organic resin coating seamless can in any one of Claims 1-8 characterized by the above-mentioned.   The organic resin-coated seamless can according to any one of claims 1 to 9, wherein the seamless can is an aluminum seamless can.