JPH11235784A - Resin-coated metal plate, metal can, and can cover - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin-coated metal plate having a high temperature resistant and moisture resistance durable against a retort sterilization and remarkably excellent impact resistance after the sterilization. SOLUTION: In the resin-coated metal plate comprising a metal base, and a thermoplastic polyester layer provided on a surface of the base, the polyester layer contains a modified polyester layer which contains a composition of athermoplastic polyester and 0.05 to 20 wt.% of epoxy resin per the polyester. The polyester in the composition is a polyester derivated from a carboxylic acid component containing an aromatic dicarboxylic acid as a main body and an alcohol component containing an aliphatic diol as a main body.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin-coated metal plate, a metal can, and a can lid, and more particularly, to a resin-coated metal plate having excellent workability, adhesion, high-temperature wet-heat resistance and impact resistance. And a metal can and a can lid formed from the resin-coated metal plate and having the above characteristics.

[0002]

2. Description of the Related Art A resin-coated metal plate in which a metal material is coated with a thermoplastic polyester film has been known for a long time as a material for cans, and this laminate is drawn or drawn.
It is also well-known that ironing is performed to form a seamless can for filling beverages or the like, or that this is press-molded to form a can lid such as an easy open end.

[0003] From the viewpoints of processability, corrosion resistance, flavor retention and the like, a thermoplastic polyester to be laminated on a metal material is mainly composed of an ethylene terephthalate unit and, if desired, a polyester or a copolyester containing other ester units. Has been used.

Japanese Patent Laid-Open No. 3-101 proposed by the present inventors.
No. 930 discloses a laminate of a metal plate, a polyester film layer mainly composed of ethylene terephthalate units, and an adhesive primer layer interposed between the metal plate and the polyester film layer if necessary. In the formula, IA is parallel to the surface of the polyester film and has a plane spacing of about 0.34 nm (CuKα X-ray diffraction angle is from 24 ° to 28 °).
゜) X-ray diffraction intensity by the diffraction plane, IB is about 0.39 nm (CuKαX
X-ray diffraction intensity by a diffraction surface having a X-ray diffraction angle of 21.5 ° to 24 °).
5 and the anisotropy index of the in-plane orientation of the crystal is 3
A coated metal plate for a can is described which comprises a film layer having a thickness of 0 or less.

[0005]

A seamless can formed from a laminate coated with a thermoplastic polyester has a satisfactory evaluation of corrosion resistance as a beverage can. There is a demand for further improvement in adhesion to a metal substrate and further improvement in workability for high-speed can making. Furthermore, in order to further improve the preservability of the contents to be filled, improvement of high-temperature, high-humidity and heat resistance, which withstands retort sterilization, and improvement of impact resistance after retort sterilization have also become important technical issues.

However, it has become increasingly difficult to simultaneously achieve these properties by adjusting the composition and physical properties of the thermoplastic polyester. Polyesters mainly composed of ethylene terephthalate units and ethylene naphthalate units have low adsorption of aromatic components in the contents, have excellent barrier properties against corrosive components, and have excellent impact resistance. In the oriented state, it has a certain degree of resistance to high-temperature and high-humidity heat, but tends to be inferior in adhesiveness and workability. The impact resistance is remarkably inferior.

[0007] Many attempts have been made to solve this problem. For example, a method using a blend of various polyesters, a method using a laminate of various polyesters, and the like have been tried. The problem has not been drastically solved.

Accordingly, it is an object of the present invention to provide a resin-coated metal plate having high temperature, high humidity and heat resistance to withstand retort sterilization, and remarkably excellent impact resistance after retort sterilization. Another object of the present invention is to provide a resin-coated metal plate which further improves the adhesion of a coating resin layer to a metal substrate and has workability capable of coping with high-speed can-making. Still another object of the present invention is to provide a metal can and a can lid having these characteristics.

[0009]

According to the present invention, in a resin-coated metal plate comprising a metal substrate and a thermoplastic polyester layer provided on the surface of the substrate, the thermoplastic polyester layer comprises at least thermoplastic polyester and A resin-coated metal plate is provided which contains a modified polyester layer composed of a composition with 0.05 to 25% by weight of an epoxy resin or an epoxy-modified resin per polyester. In the resin-coated metal plate of the present invention, The thermoplastic polyester in the composition is a polyester derived from a carboxylic acid component mainly composed of an aromatic dicarboxylic acid and an alcohol component mainly composed of an aliphatic diol, especially 50% by mole or more of the carboxylic acid component is terephthalic acid. And 50 of the alcohol component
1. mol% or more of an ethylene glycol component; 2. the epoxy resin has an epoxy equivalent of 150 to 5000; The epoxy resin is an epoxy resin derived from bisphenols and epihalohydrin, an epoxy resin derived from novolaks and epihalohydrin or a modified product thereof, or an unsaturated epoxy compound is copolymerized or graft copolymerized. 3. a resin; 4. the modified polyester layer further contains at least one modified resin component selected from the group consisting of an ethylene-based polymer, a thermoplastic elastomer, a polyarylate, and a polycarbonate; The resin-modifying component has a content of 5 per thermoplastic polyester.
5. it is contained in an amount of up to 0% by weight; It is preferable that the modified polyester layer is located at least on the side in contact with the metal substrate. According to the present invention, there is also provided a metal can and a can lid formed from the resin-coated metal plate.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [Action] The present invention relates to a resin-coated metal plate comprising a metal substrate and a thermoplastic polyester layer provided on the surface of the substrate. As the thermoplastic polyester layer, a thermoplastic polyester and the polyester are used. Characterized by using at least a modified polyester layer composed of a composition of 0.05 to 25% by weight of an epoxy resin or an epoxy modified resin. Grant,
Moreover, the impact resistance after retort sterilization can be significantly improved.

As shown in the examples described below, a resin-coated metal plate on which a cast film of polyethylene terephthalate alone is laminated is highly whitened (thermal crystallization) when subjected to a retort sterilization treatment at 135 ° C. for 30 minutes, and the coating is extremely high. It is in a brittle state (see Comparative Example 1). On the contrary,
When a resin-coated metal plate obtained by laminating a cast film of a composition in which 1% by weight of an epoxy resin (Epicoat # 1001) was mixed with polyethylene terephthalate was subjected to the same retort sterilization treatment, surprisingly, no whitening occurred, The coating is kept intact (see Example 1).

Deterioration of polyethylene terephthalate under retort conditions is largely attributable to the remarkable progress of thermal crystallization of polyester under high-temperature, high-humidity heat conditions. It is thought that the further promotion of thermal crystallization due to the formation reaction and the decrease in molecular weight is another major cause.

On the other hand, according to the present invention, the whitening and deterioration tendency of the resin coating layer is remarkably suppressed by a simple operation of adding a small amount of an epoxy resin or an epoxy-modified resin into the polyester. This indicates that the compounded epoxy resin or epoxy-modified resin is effectively acting on suppression of thermal crystallization of polyester and further suppression of degradation due to hydrolysis.

Practical impact resistance required for actual canned products includes what is called dent resistance. This means that even if the canned product falls or collides with each other and a dent called a dent occurs on the canned product, the adhesion and coverage of the coating can be completely maintained. Is required. That is, if the coating peels off or pinholes or cracks enter the coating in the dent test, metal elution or leakage due to pitting corrosion occurs from this portion, causing a problem of losing the preservability of the contents. . In general, polyesters having excellent content resistance are generally lacking in the property of absorbing or mitigating impact during a dent test, and the provision of these properties is an important issue.

When a resin-coated metal plate on which a polyethylene terephthalate single cast film is laminated is subjected to an iron ball drop test from a height of 40 mm without retort treatment and then an enamellator test is performed, the current value (ERV) is as follows. Although the level reaches 10 mA, the resin-coated metal sheet laminated with the above-mentioned epoxy resin-containing polyester only shows an enamellator current value of 0.05 mA in a similar test. This tendency is also observed when the resin-coated metal plate after the retort sterilization is subjected to the above test.

From the above experimental facts, the components such as the epoxy resin compounded in the polyester coating layer not only enhance the impact resistance of the resin-coated metal plate but also significantly improve the adhesion to the metal substrate and the coating performance. It becomes clear that there is.

Further, the resin-coated metal sheet provided with a polyester layer containing an epoxy resin or an epoxy-modified resin is formed into a can body by drawing and deep drawing, drawing and ironing, or neck-in processing, flange processing. Even when subjected to secondary processing such as bead processing, circumferential polyhedral wall processing, bulge processing, etc., the workability and adhesion are remarkably excellent without generating cracks, pinholes, peeling and the like. The same applies to the case where the resin-coated metal plate is subjected to press forming, score processing, rivet processing, and the like to form a can lid.

In the modified polyester layer used in the present invention,
At least one modified resin component selected from the group consisting of an ethylene polymer, a thermoplastic elastomer, a polyarylate, and a polycarbonate can be further contained, thereby further improving high-temperature wet heat resistance and impact resistance. be able to.

[Outline of Resin-Coated Metal Plate] In FIG. 1 showing an example of a cross-sectional structure of the resin-coated metal plate of the present invention, the resin-coated metal plate 1 is on the inner surface side when a metal base 2 and a container are formed. And a modified polyester layer 3 provided on the side. The thermoplastic polyester layer 4 is also formed on the outer surface side of the container of the metal base 2, and the polyester layer 4 on the outer surface side may be made of modified polyester or may be made of another polyester coating layer. .

FIG. 2 shows another example of the cross-sectional structure of the resin-coated metal plate. In FIG. 2, a modified polyester base layer 3 located on the side in contact with the metal base and a polyester surface layer 5 other than the above are provided on the inner surface of the container. This is the same as FIG. 1 except that the laminated resin layer 6 is provided.

[Metal Plate] In the present invention, various surface-treated steel plates or light metal plates such as aluminum are used as the metal plate.

As the surface-treated steel sheet, a cold-rolled steel sheet is annealed and then subjected to secondary cold rolling, and is subjected to one or more surface treatments such as zinc plating, tin plating, nickel plating, electrolytic chromic acid treatment, and chromic acid treatment. Can be used.
An example of a suitable surface-treated steel sheet is an electrolytic chromic acid-treated steel sheet, particularly provided with a chromium metal layer of 10 to 200 mg / m ² and a chromium oxide layer of 1 to 50 mg / m ² (in terms of chromium metal). This is excellent in the combination of coating film adhesion and corrosion resistance. Another example of a surface-treated steel plate is a hard tin plate having a tin plating amount of 0.5 to 11.2 g / m ² . This tin plate is desirably subjected to chromic acid treatment or chromic acid-phosphoric acid treatment so that the amount of chromium is 1 to 30 mg / m ^{2 in} terms of metal chromium.

As still another example, an aluminum-coated steel sheet subjected to aluminum plating, aluminum pressure welding, or the like is used.

As the light metal plate, an aluminum alloy plate is used in addition to a so-called aluminum plate. An aluminum alloy plate excellent in corrosion resistance and workability has a Mn: 0.
2 to 1.5% by weight, Mg: 0.8 to 5% by weight, Z
n: 0.25 to 0.3% by weight, Cu: 0.15 to 0.25% by weight, with the balance being Al. It is desirable that these light metal plates have also been subjected to a chromic acid treatment or a chromic / phosphoric acid treatment such that the chromium amount becomes 20 to 300 mg / m ^{2 in} terms of chromium metal.

The thickness of the metal plate, ie, the thickness of the bottom of the can (tB)
) Varies depending on the type of metal, the purpose or the size of the container, but generally preferably has a thickness of 0.10 to 0.50 mm. Among them, in the case of a surface-treated steel sheet, 0.10 to 0. It is preferable to have a thickness of 0.30 mm, and in the case of a light metal plate, a thickness of 0.15 to 0.40 mm.

[Modified polyester layer] In the present invention,
As the polyester base resin forming the modified polyester layer, the thermoplastic polyester is a polyester derived from a carboxylic acid component mainly composed of an aromatic dicarboxylic acid and an alcohol component mainly composed of an aliphatic diol, particularly the carboxylic acid component. A polyester in which 50 mol% or more is composed of a terephthalic acid component and 50 mol% or more of the alcohol component is composed of an ethylene glycol component. As long as the above conditions are satisfied, this polyester is either a homopolyester or a copolyester,
Alternatively, a blend of two or more of these may be used.

The carboxylic acid components other than the terephthalic acid component include isophthalic acid, naphthalenedicarboxylic acid, P
-Β-oxyethoxybenzoic acid, biphenyl-4,4 ′
-Dicarboxylic acid, diphenoxyethane-4,4'-dicarboxylic acid, 5-sodium sulfoisophthalic acid, hexahydroterephthalic acid, adipic acid, sebacic acid, trimellitic acid, pyromellitic acid, and the like.

On the other hand, alcohol components other than ethylene glycol include 1,4-butanediol, propylene glycol, neopentyl glycol, 1,6-hexylene glycol, diethylene glycol, triethylene glycol, cyclohexane dimethanol, and ethylene of bisphenol A. Alcohol components such as oxide adducts, glycerol, trimethylolpropane, pentaerythritol, dipentaerythritol, and sorbitan can be exemplified.

Examples of suitable thermoplastic polyesters include, but are not limited to, polyethylene terephthalate, polybutylene terephthalate, polyethylene-2,
6-naphthalate, polyethylene terephthalate / isophthalate, polybutylene terephthalate / isophthalate, polyethylene-2,6-naphthalate / terephthalate, polyethylene terephthalate, polybutylene terephthalate / adipate, polyethylene-2,6-naphthalate / isophthalate, polybutylene terephthalate / Adipate or a blend of two or more of these.

The base polymer of the polyester 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 a solvent is 0.5 or more, especially 0.6. The range of from 1.5 to 1.5 is good in terms of barrier properties against corrosive components and mechanical properties.

[Epoxy Resin] In the present invention, the epoxy resin to be blended in the polyester is a compound containing two or more epoxy groups in one molecule. The epoxy resin preferably has an epoxy equivalent of 150 to 5000, particularly 400 to 4000. As long as the epoxy resin has the epoxy equivalent, a liquid, semi-solid or solid epoxy resin is used.

When the epoxy equivalent falls below the above range,
When kneading with polyester, it is not preferable because the epoxy resin volatilizes or it becomes difficult to blend with the polyester, or the compounded epoxy resin has a high tendency to extract. This is not preferred because the tendency of dispersion into the interior tends to worsen. Furthermore, in any of these cases, the high-temperature wet heat resistance and impact resistance of the modified polyester layer tend to be lower than when the epoxy equivalent is within the above range.

The following epoxy resins are used. For example, the following are used. (1) Bisphenol type epoxy resin: An epoxy resin derived from bisphenols such as bisphenol A, bisphenol F, bisphenol B and epihalohydrin. The bisphenols incorporated into the epoxy resin include 2,2-bis (4-hydroxyphenyl) propane, 2,2-bis (4-hydroxyphenyl) butane, and 1,1-bis (4-hydroxyphenyl)
P such as ethane and bis (4-hydroxyphenyl) methane
Although the -p form is generally used, the op form such as bis (2-hydroxyphenyl) methane and the op form such as 2-hydroxyphenyl-4-hydroxyphenylmethane) are also used.
It can be used alone or in combination with the pp form. (2) Novolak type epoxy resin: an epoxy resin derived from a novolak type phenol resin and epihalohydrin. When phenols and formaldehyde are reacted with acid, novolak is formed. Examples of phenols include phenol (phenyl carbonate), m-cresol, m-ethylphenol, 3,5-xylenol, m-methoxyphenol, o-cresol, p-cresol, and p-tert.
Monofunctional phenols such as butylphenol, p-ethylphenol, 2,3-xylenol, 2,5-xylenol, 2,4-xylenol and 2,6-xylenol; p-tert-amylphenol, p-nonylphenol, p-tert-amylphenol -Phenylphenol, p-cyclohexylphenol, bisphenols and the like are used alone or in combination of two or more. (3) A glycidyl etherified epoxy resin of a polyvalent polycyclic phenol such as 1,1,2,2-tetrakis (4-hydroxyphenyl) ethane. (4) A glycidyl etherified epoxy resin of a hydride of a phenol compound. (5) Glycidyl etherified epoxy resins of polyhydric phenols such as catechol, rusorcin, hydroquinone, and phloroglucin. (6) Glycidyl etherified epoxy resins of polyhydric alcohols such as ethylene glycol, butanediol, glycerol, erythritol, and polyoxyalkylene glycol. (7) Alicyclic epoxy resins such as vinylcyclohexene dioxide, limonene dioxide and dicyclopentadiene oxide. (8) Polyglycidyl esterified epoxy resin of ester condensate of phthalic acid and cyclohexane-1,2-dicarboxylic acid. (9) Polyglycidylamine-based or amide-based epoxy resins. (10) a resin obtained by reacting the epoxy resin with a resin having a functional group such as a hydroxyl group, a carboxyl group, an acid anhydride group, an amino group, or an amide group at a terminal or a side chain;
A resin obtained by reacting an aliphatic carboxylic acid, an aliphatic alcohol, an aliphatic amine or the like with the epoxy resin. (11) A resin in which an unsaturated epoxy monomer is introduced by means such as copolymerization or graft copolymerization is used. Examples of unsaturated epoxy monomers include glycidyl esters of unsaturated monocarboxylic acids such as glycidyl acrylate, glycidyl methacrylate, and glycidyl p-styryl carboxylate; maleic acid, itaconic acid, citraconic acid, butenetricarboxylic acid, and endo-cis. -Bicyclo [2,2,1
And unsaturated polycarboxylic acids such as hept-5-ene-2,3-dicarboxylic acid and endo-cis-bicyclo [2,2,1] hept-5-ene-2-methyl-2,3-dicarboxylic acid. Monoglycidyl ester or polyglycidyl ester; allyl glycidyl ether, 2-methylallyl glycidyl ether, glycidyl ether of o-allyl phenol, glycidyl ether of m-allyl phenol, glycidyl ether of p-allyl phenol, isopropenyl Glycidyl ether of phenol, glycidyl ether of o-vinylphenol, m-
Unsaturated glycidyl ethers such as glycidyl ether of vinylphenol and glycidyl ether of p-vinylphenol; 2- (o-vinylphenyl) ethylene oxide, 2- (p-vinylphenyl) ethylene oxide,
-(O-vinylphenyl) propylene oxide, 2-
(P-vinylphenyl) propylene oxide, 2- (o
-(Allylphenyl) ethylene oxide, 2- (p-allylphenyl) ethylene oxide, 2- (o-allylphenyl) propylene oxide, 2- (p-allylphenyl) propylene oxide, p-glycidylstyrene, 3,4 -Epoxy-1-butene, 3,4-epoxy-3-methyl-1-butene, 3,4-epoxy-1-pentene, 3,4-epoxy-3-methyl-1-pentene, 5,6-epoxy Preferred are -1-hexene, vinylcyclohexene monoxide, and allyl-2,3-epoxycyclopentyl ether. Examples of this type of resin include an epoxy-modified olefin resin and an epoxy-modified acrylic resin.

[Modified polyester composition] In the present invention,
The above epoxy resin is added to polyester, polyester 10
Blend at a ratio of 0.05 to 25 parts by weight, particularly 0.1 to 15 parts by weight per 0 parts by weight. When the blend ratio of the epoxy resin is below the above range, the improvement in high-temperature wet heat resistance and impact resistance is insufficient compared to the case where the epoxy resin is within the above range, while when the blend ratio exceeds the above range, the mechanical properties of the coating layer are insufficient. There is a tendency for the barrier properties against corrosion components and corrosion components to decrease.

The modified polyester composition further contains at least one modified resin component selected from the group consisting of an ethylene polymer, a thermoplastic elastomer, a polyarylate, and a polycarbonate. Impact properties can be further improved. The modified resin component is generally used in an amount of up to 50 parts by weight, particularly preferably in an amount of 5 to 35 parts by weight, per 100 parts by weight of the polyester.

Examples of the ethylene polymer include low-, medium- or high-density polyethylene, linear low-density polyethylene, linear ultra-low-density polyethylene, ethylene-propylene copolymer, and ethylene-butene-1 copolymer. , An ethylene-propylene-butene-1 copolymer, an ethylene-vinyl acetate copolymer, an ion-crosslinked olefin copolymer (ionomer), an ethylene-acrylate copolymer, and the like. Of these, ionomers are preferred, and as the base polymer of the ionomer, ethylene- (meth) acrylic acid copolymer, ethylene- (meth) acrylic acid ester- (meth) acrylic acid copolymer, ion As seeds, those of Na, K, Zn and the like are used.

Examples of the thermoplastic elastomer include styrene-butadiene-styrene block copolymer, styrene-isoprene-styrene block copolymer, hydrogenated styrene-butadiene-styrene block copolymer, and hydrogenated styrene-isoprene-styrene block. A copolymer or the like is used.

The polyarylate is defined as a polyester derived from a dihydric phenol and a dibasic acid. As the dihydric phenol, bisphenols include 2,2'-bis (4-hydroxyphenyl) propane ( Bisphenol A), 2,2′-bis (4-hydroxyphenyl) butane (bisphenol B), 1,1 ′
-Bis (4-hydroxyphenyl) ethane, bis (4-
(Hydroxyphenyl) methane (bisphenol F), 4
-Hydroxyphenyl ether, p- (4-hydroxy) phenol and the like are used, but bisphenol A and bisphenol B are preferred. As dibasic acids,
Terephthalic acid, isophthalic acid, 2,2- (4-carboxyphenyl) propane, 4,4′-dicarboxydiphenyl ether, 4,4′-dicarboxybenzophenone and the like are used. The polyarylate may be a homopolymer derived from the above monomer component or a copolymer. Further, a copolymer of an ester unit derived from an aliphatic glycol and a dibasic acid may be used as long as the essence is not impaired. These polyarylates are
Unitika U-Series or AX Series of U-Polymer, ArdelD-100 from UCC, APE from Bayer, Durel, DuPont from Hoechst
Available from Arylon of Kaneka Corporation and NAP resin of Kaneka Chemical Corporation.

Polycarbonate is a carbonate resin derived from bicyclic dihydric phenols and phosgene,
It is characterized by having a high glass transition point and heat resistance. Examples of the polycarbonate include bisphenols such as 2,2′-bis (4-hydroxyphenyl) propane (bisphenol A), 2,2′-bis (4-hydroxyphenyl) butane (bisphenol B),
1'-bis (4-hydroxyphenyl) ethane, bis (4-hydroxyphenyl) methane (bisphenol F), 1,1-bis (4-hydroxyphenyl) cyclohexane, 1,1-bis (4-hydroxyphenyl) cyclo From pentane, 1,1-bis (4-hydroxyphenyl) -1-phenylmethane, 1,1-bis (4-hydroxyphenyl) -1-phenylethane, 1,2-bis (4-hydroxyphenyl) ethane, etc. Derived polycarbonates are preferred.

The polyester and the epoxy resin or the modified resin component can be blended by dry blending or melt blending depending on the properties of the epoxy resin. In the former case, the resin is blended with a blender, a Henschel mixer or a super mixer. And the like, and may be directly supplied to the hopper of the extruder. In the latter case, the mixture may be kneaded with a single-screw or twin-screw extruder, a kneader, a Banbury mixer, or the like. In any of these cases, the polyester and the epoxy resin are finally blended at a temperature equal to or higher than the melting temperature of the polyester. It is also possible to produce a polyester / epoxy resin masterbatch containing a relatively high concentration of epoxy resin and blend this masterbatch with the polyester.

It should be noted that there is no difference in the effect of the present invention even if a reaction occurs between the polyester and the epoxy resin when the polyester and the epoxy resin are blended. That is, in the polyester, functional groups such as a terminal hydroxyl group and a terminal carboxyl group are present, and under the condition that the polyester and the epoxy resin are in contact with each other at a temperature higher than the melting temperature of the polyester (generally, 200 ° C. or higher), these conditions are satisfied. It is believed that a reaction has occurred between the functional group and the epoxy group. By this reaction, the polyester molecular chain
Intermolecular crosslinking may have occurred. There is a theory that the terminal carboxyl group has a bad influence on the degradation due to hydrolysis of the polyester, but the reaction with the epoxy resin may have a good effect on suppressing the hydrolysis.

In the modified polyester layer used in the present invention,
Known resin blending agents can be blended.
For example, by adding an antioxidant, particularly an antioxidant having a molecular weight of 400 or more, the heat resistance of the laminate for cans can be significantly improved.

Examples of the above-mentioned polymer phenolic antioxidant include tetrakis [methylene-3 (3 ′, 5 ′)
-Di-t-butyl-4'-hydroxyphenyl) propionate) methane (molecular weight 1177.7), 1,1,3
-Tris (2-methyl-4-hydroxy-5-t-butylphenyl) butane (molecular weight 544.8), 1,3,5
-Trimethyl-2,4,6-tris (3,5-di-t-
Butyl-4-hydroxybenzyl) benzene (molecular weight 7
75.2), bis [3,3'-bis- (4'-hydroxy-3'-tert-butylphenyl) butyric acid]
Glycol ester (molecular weight 794.4), 1,3,5
-Tris (3'5'-di-t-butyl-4'-hydroxybenzyl) -s-triazine 2,4,6- (1H,
3H, 5H) trione (molecular weight 783.0), triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate] (molecular weight 586.8), 1,6-hexane For example, diol-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate (molecular weight 638.9) can be used. Among them, particularly, tetrakis [methylene-3
(3 ′, 5′-Di-tert-butyl-4′-hydroxyphenyl) propionate) methane is preferred.

Other examples of antioxidants having a molecular weight of 400 or more include tocopherol-based antioxidants such as α-type, β-type
-, Γ-, and δ-type tocopherols. α-Tocopherol is particularly preferred.

These antioxidants are polyester 10
It is preferably used in an amount of 0.01 to 1.5 parts by weight per 0 parts by weight.

Of course, the polyester composition may contain other resin compounding agents known per se, such as an antiblocking agent such as amorphous silica, a pigment such as titanium dioxide (titanium white), various antistatic agents, and a lubricant. Etc. can be blended according to a known formulation.

In the resin-coated metal sheet of the present invention, the polyester coating provided on the metal substrate may be composed of a modified polyester layer alone or a laminate of the modified polyester layer and at least one other polyester layer. Layer. In the case of the latter laminate, it is necessary that the modified polyester layer be present at least on the side in contact with the metal substrate from the viewpoint of high-temperature wet-heat resistance and impact resistance.

For example, in the case of a coating layer composed of a laminate of a modified polyester layer and another polyester layer, the modified polyester layer should be a base layer, the other polyester layer should be a surface layer, and the polyester surface The layer is preferably made of a polyester layer having excellent content resistance.

Specifically, in the polyester surface layer, 50 mol% or more, particularly 70 mol% or more of the carboxylic acid component is composed of the terephthalic acid or naphthalenedicarboxylic acid component, and 50 mol% or more, especially 70 mol% of the alcohol component.
What has been described above is a polyester comprising an ethylene glycol component, which has a glass transition point of 50 ° C. or more, particularly preferably 60 ° C. or more. Suitable examples include polyethylene terephthalate, polyethylene terephthalate / isophthalate, polyethylene naphthalenedicarboxylate, polyethylene naphthalenedicarboxylate / terephthalate, and the like. These polyester surface layers should also have an intrinsic viscosity in the range already mentioned.

In the present invention, the polyester coating layer comprises:
Having a thickness of 1 to 60 μm as a whole, particularly 2 to 40 μm, may be sufficient in terms of the balance between protection of the metal substrate and workability. On the other hand, in the case of a laminated coating layer, the modified polyester layer and the other polyester layers are different from each other. , 1: 40-40:
A thickness ratio of 1 and particularly a thickness ratio of 1:20 to 20: 1 is preferable in terms of resistance to high-temperature wet heat and balance between impact resistance and content resistance.

[Resin-Coated Metal Plate and Production Thereof] The polyester coating layer can be formed on the metal substrate by any means, for example, extrusion coating, cast film heat bonding, and biaxially stretched film heat bonding. It can be performed by a method or the like.

In the case of the extrusion coating method, the polyester is extruded through a die using a number of extruders corresponding to the type of the resin layer, and the polyester is extruded and coated in a molten state on a metal substrate to be thermally bonded.

Referring to FIG. 3 for explaining a method of manufacturing a resin-coated metal plate by an extrusion coating method, a metal plate 11 is preheated by heating rolls 12 a and 12 b as required and supplied between a chill roll 13 and a nip roll 14. on the other hand,
The polyester is extruded into a thin film 16 through the die head 15 of the extruder, and the chill roll 13 and the nip roll 1 are extruded.
It is supplied so as to overlap with the metal plate 11 between the four. The chill roll 13 and the nip roll 14 are forcibly cooled, and a thin film 16 made of a composite polyester is pressure-bonded to the metal plate 11 to thermally bond the two and rapidly cool from both sides to obtain a laminate 17. The coated metal plate after heat bonding is
It is led to a cooling water tank and quenched to prevent thermal crystallization.

The thermal adhesion of the composite polyester composition to the metal substrate is performed by the heat of the molten polyester layer and the heat of the metal plate. The heating temperature (T ₁ ) of the metal plate is generally from 90 to 290 ° C., preferably from 100 to 280 ° C.

In the case of a production method using a polyester film, a roll of a polyester film is provided instead of the die head shown in FIG.
What is necessary is just to supply between 3 and the nip roll 14.

The above-mentioned laminated film is obtained by forming the above-mentioned coextrudate into a film by a T-die method or an inflation film forming method. As the film, an unstretched film obtained by quenching the extruded film and casting can be used.The film is stretched at the stretching temperature sequentially or simultaneously biaxially, and the stretched film is heat-set. Can also be used.

The degree of biaxial orientation of the polyester film can be confirmed by X-ray diffraction, polarization fluorescence, birefringence, density gradient tube method, and the like. The degree of biaxial stretching of the film is such that the surface layer polyester is 0.04 to 0.18.
Are suitable. The stretching of the film is generally carried out at a temperature of from 80 to 130 ° C. and an area stretching ratio of 2.
From the range of 5 to 16.0, particularly 4.0 to 14.0, the stretching ratio at which the birefringence falls within the above range is selected in relation to the type of polyester and other conditions. Further, the heat setting of the film is performed at 130 to 240 ° C., particularly 150 to 230 ° C.
, A heat setting temperature that also satisfies the above conditions is selected.

Although not generally required, an adhesive primer layer may be provided between the polyester film and the metal material, if desired. This adhesive primer exhibits excellent adhesiveness to both the metal material and the film. A typical primer paint excellent in adhesion and corrosion resistance is a phenol epoxy paint composed of a resol type phenol aldehyde resin derived from various phenols and formaldehyde, and a bisphenol type epoxy resin, In particular, the phenol resin and the epoxy resin are mixed in a weight ratio of 50:50 to 1:99, especially 4:50.
It is a paint contained in a weight ratio of 0:60 to 5:95.
Generally, the adhesion primer layer is preferably provided with a thickness of 0.01 to 10 μm. The adhesive primer layer may be provided in advance on a metal material or may be provided in advance on a polyester film.

[Metal Can and Manufacturing Method Thereof] The metal can of the present invention may be formed by any can-making method as long as it is formed from the above-mentioned resin-coated metal plate. The metal can can be a three-piece can having a side seam, but is generally preferably a seamless can (two-piece can). This seamless can is manufactured by means such as drawing, drawing / deep drawing, drawing / ironing, and the like. The side wall portion is bent or stretched by drawing and redrawing of the resin-coated metal plate, or is further ironed to form a laminate having a thickness of 2 mm.
Preferably, the thickness is reduced to a thickness of 0 to 95%, particularly 30 to 85%.

In the seamless can of the present invention, the above resin-coated metal plate is drawn between a punch and a die into a cup having a bottom.
It is manufactured by deep drawing, bending and elongating at the deep drawing stage, or further thinning the cup side wall by ironing. That is, the deformation for thinning is performed by a combination of the deformation (bending and elongation) due to the load in the can axis direction (height direction) and the deformation (ironing) due to the load in the can thickness direction, and in this order. The above processing imparts a molecular orientation in the direction of the can axis.

The drawing-ironing of the resin-coated metal plate is performed by the following means. That is, as shown in FIG. 4, a pre-draw cup 30 formed from a coated metal plate includes an annular holding member 31 inserted into the cup and a re-drawing member located thereunder.
It is held by the ironing die 32. These holding members 3
1 and redrawing-redrawing-ironing punch 33 so as to be coaxial with the ironing die 32 and to be able to enter and exit the holding member 31.
Is provided. The redrawing-ironing punch 33 and the redrawing-ironing die 32 are relatively moved so as to bite each other.

The redrawing-ironing die 32 has a flat portion 34 at the upper portion, and a working corner portion 35 having a small radius of curvature on the periphery of the flat portion, and has a diameter decreasing downwardly around the working corner portion. Tapered approach portion 36
Following the approach portion, a cylindrical ironing land portion (ironing portion) 38 is provided via a curvature portion 37. An inverted tapered relief 39 is provided below the land portion 38.
Is provided.

The side wall of the front drawing cup 30 is bent perpendicularly inward from the outer peripheral surface 40 of the annular holding member 31 through the curvature corner portion 41 to re-draw with the annular bottom surface 42 of the annular holding member 31. It passes through a portion defined by the flat portion 34 of the die 32 and is bent substantially vertically in the axial direction by the working corner portion 35 of the redraw die 32, and is formed into a deep drawn cup having a smaller diameter than the front drawn cup 30. At this time, the portion of the working corner 35 opposite to the side in contact with the corner 35 is elongated by bending deformation, while the portion in contact with the working corner 35 is returned after leaving the working corner. It is stretched by deformation, whereby the side wall is thinned by bending and stretching.

The side wall portion thinned by bending and stretching is
The outer surface thereof comes into contact with the approach portion 36 having a small taper angle whose diameter is gradually reduced, and the inner surface is guided to the ironing portion 38 in a free state. The process of passing the side wall portion through the approach portion is a stage prior to the subsequent ironing process, and stabilizes the laminate after bending and stretching, and slightly reduces the diameter of the side wall portion to prepare for ironing. In other words, the laminate immediately after bending and stretching is affected by vibrations caused by bending and stretching, distortion remains inside the film, and the film is still in an unstable state. Although it is not possible to perform the ironing process, the outer surface of the side wall portion is brought into contact with the approach portion 36 to reduce the diameter, and the inner surface is free, so that the influence of vibration is prevented and the inside of the film is prevented. In addition, the non-homogeneous distortion of the steel sheet is alleviated, and the heat generated by the bending and elongation is also taken away, thereby enabling smooth and smooth ironing.

The side wall passing through the approach portion 36 is introduced into the gap between the ironing land portion (ironing portion) 38 and the re-drawing-ironing punch 33, and is rolled to a thickness regulated by the gap (C1). You. The thickness C1 of the final side wall portion is determined so as to be 20 to 95%, particularly 30 to 85% of the original thickness (t) of the laminate. In addition, the curvature portion 37 on the ironing portion introduction side smoothly introduces the laminate into the ironing portion 38 while effectively fixing the ironing start point, and has a reverse tapered relief below the land portion 38. Reference numeral 39 is for preventing an excessive increase in the processing force.

The radius of curvature Rd of the curvature corner portion 35 of the redrawing-ironing die 32 should be 2.9 times or less the thickness (t) of the laminate for effective bending and elongation. If the radius of curvature is too small, the laminate will break, so it should be at least one time the thickness (t) of the laminate.

The approach angle α (１ ／ of the taper angle) α of the tapered approach portion 36 should be 1 to 8 °. When the angle of the approach portion is smaller than the above range, relaxation of the orientation of the polyester film layer and stabilization before ironing become insufficient, and when the angle of the approach portion is larger than the above range, the bending and elongation are uneven (return). (Sufficient deformation), and in any case, smooth smooth ironing becomes difficult without cracking or peeling of the film.

The land 38 for ironing, the re-stretching-ironing punch 33 and the clearance are in the above-mentioned ranges, but the land length L is generally preferably 0.5 to 3 mm. If the length is larger than the above range, the working force tends to be excessively large. On the other hand, if the length is smaller than the above range, the return after ironing is large, which may be undesirable.

In the seamless can of the present invention, since the polyester layer on the flange portion is subjected to severe tightening, it is preferable that the polyester layer be mildly processed as compared with the polyester layer on the side wall of the can. Thereby, the sealing performance and corrosion resistance of the tightened portion can be improved. For this purpose, a flange forming portion thicker than the thickness of the can side wall is formed at the upper end of the can side wall after ironing.
That is, the thickness of the can side wall is t1 and the thickness of the flange is t.
Assuming that 2, the ratio of t2 / t1 is preferably set in the range of 1.0 to 2.5, particularly 1.0 to 2.0.

In producing the seamless can of the present invention, the composite polyester layer on the surface imparts sufficient lubricating performance. However, in order to further enhance lubricity, a lubricant such as various oils or waxes is used. Apply a small amount,
The processing can be performed with solid surface lubrication. Of course, an aqueous coolant containing a lubricant (of course, also serving as cooling) can be used, but should be avoided in terms of simplicity of operation.

The temperature during redrawing and ironing (the temperature immediately after the completion of ironing) is preferably a temperature not higher than 50 ° C. higher than the glass transition point (Tg) of the polyester and not lower than 10 ° C. For this reason, it is preferable to heat the tool or conversely cool it.

According to the present invention, the drawn container can then be subjected to at least one stage of heat treatment. This heat treatment has various purposes, and mainly includes removing residual strain of a film generated by processing, volatilizing a lubricant used for processing from a surface, and drying and curing a printing ink printed on the surface. Is the purpose. For this heat treatment, a heating device known per se, such as an infrared heater, a hot air circulation furnace, and an induction heating device, can be used. In addition, this heat treatment may be performed in one stage, or may be performed in two or more stages. The heat treatment temperature is 180 to 3
A range of 00 ° C is appropriate. The heat treatment time is generally on the order of 1 to 10 minutes.

The container after the heat treatment may be rapidly cooled or left to cool. That is, in the case of a film or a laminate, the quenching operation is easy, but in the case of a container, the quenching operation in an industrial sense is difficult because it is three-dimensional and has a large heat capacity due to metal. In the present invention, even without a quenching operation, crystal growth is suppressed, and excellent combination characteristics can be obtained. Of course, if desired, it is optional to employ a rapid cooling means such as blowing cold air or spraying cooling water.

The obtained can is subjected to one-stage or multi-stage neck-in processing, if necessary, and flanged to obtain a can for winding. Prior to neck-in processing, bead processing or circumferential polyhedral wall processing described in Japanese Patent Publication No. 7-5128 can be performed.

[Can lid and production thereof] The resin-coated metal plate of the present invention can be applied to the production of can lids such as easy open lids.

In FIG. 5 showing the upper surface of the easy open can lid of the present invention and FIG.
Numeral 0 is formed from the above-mentioned resin-coated metal plate, and has a sealing groove 52 on the outer peripheral side via an annular rim portion (counter sink) 51 to be fitted to the inner surface of the can body side surface. A portion 53 to be opened inside the rim portion 51
Is provided. A rivet 55 formed by projecting a lid material to the outer surface of the can lid is formed near the outside of the portion 53 to be opened, and a tab 56 for opening is formed by riveting the rivet 55 below. It is fixed as shown. That is, the opening tab 5
6 has a tip 57 for opening by pushing and tearing at one end and a ring 58 for holding at the other end, and has a fulcrum portion 59 fixed by a rivet 55 near the tip 57 for opening. Although the portion 53 to be opened is generally surrounded by the score 54, a part of the cover 50 is not covered by the cover 54 without passing through the score 54.
Is joined to. The above-described sealing groove 52 is lined with a compound (sealant) 60 of a sealing rubber composition, and sealing is performed between the compound and the can body flange.

At the time of opening, the ring 58 of the opening tab 56 is held and lifted upward. As a result, the opening tip 57 of the opening tab 56 is pushed downward, and a part of the score 54 starts to be sheared. Next, by holding the ring 58 and pulling it upward, the remaining portion of the score 54 is broken and opening is easily performed. In the lid 50 of this type, the tab 56 does not separate from the lid together with the opening 53 and remains on the lid.

The lid in the above specific example is a so-called stay-on-tab, but it is of course applicable to a fully open easy-open lid.

The can lid of the present invention is produced by a means known per se except that the above-mentioned resin-coated metal plate is used.
This step will be described. First, in a press forming step, a resin-coated metal plate is punched into a disk shape and formed into a desired lid shape.

Next, in the score stamping step, the score is stamped using a score die so that the score reaches the middle of the metal material from the outer surface side of the lid. The residual thickness (t2) of the metal material in the score is preferably such that t2 / t1 × 100 is 10 to 50% and t2 is 20 to 150 μm with respect to the original thickness (t1) of the metal material. Further, it is important that the bottom width (d) of the score be 75 μm or less, particularly 50 μm or less, in order to prevent the occurrence of scratches on the film layer.

In the rivet forming step, a rivet projecting from the outer surface is formed in the opening section defined by the score using a rivet forming die, and in the tab attaching step, the opening tab is fitted to the rivet, and the rivet projecting section is formed. And fix the tab. Instead of the rivet forming step, in the case of an adhesive tab, an adhesive such as a nylon-based adhesive tape is applied to the opening or tab, and the tab and the opening are thermally bonded in the tab attaching step. Finally, in the lining process,
A sealing compound is lined with a nozzle through a sealing groove of the lid and dried to form a sealant layer.
The double winding process of the lid and the can body will be described. The flange of the can body and the sealing groove of the easy-open lid are fitted together, and the groove is formed around the flange by using a primary winding roll. To the primary winding. Next, in a secondary winding step, the flange portion is further wound by 90 ° along the side wall of the can body to form a can body.

[0082]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to the following examples.

[Measurement of Epoxy Equivalent] An epoxy resin or an epoxy compound to be used is dissolved in chloroform and acetic acid, a tetraethylammonium acetic acid solution is added to the solution, and 0.1N perchloric acid is added using a glass electrode and a reference electrode. Titration with acetic acid solution. At this time, the reading of the potentiometer and
The relationship between this and the titration of the 0.1N perchloric acetic acid solution is plotted, and the inflection point obtained in the titration curve is used as the end point to calculate the epoxy equivalent based on the amount of the consumed 0.1N perchloric acetic acid solution. did. The calculation method was based on the following equation. EE = 1000 × m2 / (0.1 × f × (V3-V4) EE: epoxy equivalent (g / eq) m2: mass of sample (g) f: factor of 0.1N perchloric acetic acid solution V3: end point Amount of 0.1N perchloric acetic acid solution consumed in titration up to (ml) V4: Amount (ml) corresponding to V in blank test

[Formation of Cast Film] Examples 1-1
5, Comparative Examples 1 to 6 were prepared by premixing a polyester resin having the composition shown in Table 1 as a first component, a second component and a third component with a Henschel mixer.
Regarding Comparative Examples Nos. To 18 and Comparative Example 7, the polyester resin having the composition shown in Table 1 as the first component, the second component and the third component were melt-blended by a batch kneader, and ground by a pin mill or the like. It was put into an extruder, melt-kneaded, extruded through a T-die so as to have a thickness of 20 μm, cooled by a cooling roll, and the obtained film was wound up to give a cast film. In Examples 19 and 20, two twin-screw extruders were used. One layer of the multilayer T-die was made of a polyester resin having the composition shown in Table 1, and the other layer was made of an acid component of polyethylene terephthalate. After melt-extruding a copolymer resin in which 12 mol% of the above was replaced with isophthalic acid, a two-layer cast film having a thickness of 10 μm / 10 μm was formed through this T-die.

[Adhesion Test] The adhesion after the processing was determined by applying a cellophane tape (24 mm width, made by Nichiban Co., Ltd.) to a place where a cross-cut was made on the molded body after the processing with a cutter, and the cellophane tape was peeled off. The evaluation was performed based on the state of peeling of the resin film from the molded article after peeling off the cellophane tape.

[Retort treatment test] After filling with distilled water at 95 ° C, retort treatment was performed at 135 ° C for 30 minutes, the temperature was returned to room temperature, distilled water was extracted, and the corrosion state of the inner surface of the can was observed.

[Flat Dent ERV Test] A resin-coated metal plate was brought into contact with a silicon rubber having a thickness of 3 mm and a hardness of 50 mm under wet conditions at 5 ° C. on the opposite side of the metal plate with the coated surface to be evaluated. Put a 5/8 inch diameter steel ball in the
Weight was dropped from 40 mm to perform impact overhang processing. 5. Determine the degree of cracking of the resin film
The measurement was performed at a current value of 00 V, an average of six samples was taken, and the metal exposure by processing was evaluated.

[Can Dent Test] After the can filled with cola was allowed to stand horizontally, at 5 ° C., the end point of the neck processing portion of the can bottom on the can axis perpendicular to the rolling direction of the metal plate. Then, a 1 kg weight having a spherical surface with a diameter of 65.5 mm was dropped from a height of 40 mm such that the spherical surface hit the can to give an impact. Thereafter, a storage test was performed at a temperature of 37 ° C., and the condition of the inner surface of the can after one year was observed.

<Examples 1 to 20> TFS steel plates (thickness of 0. 1).
A polyester film having the composition shown in Table 1 was heat-laminated on both sides (18 mm, chromium metal content: 120 mg / m2, chromium hydrated oxide content: 15 mg / m2), and immediately cooled with water to obtain a resin-coated metal plate. At this time, the temperature of the metal plate before lamination was set at 15 ° C. higher than the melting point of the polyester resin. The laminating roll temperature was 150 ° C., and the passing speed was 40 m / min. Was used for lamination. After glamor wax was uniformly applied to the organic coated metal plate, it was punched into a disk having a diameter of 160 mm, and a shallow drawn cup was formed according to a conventional method. The drawing ratio in this drawing step is 1.59. Next, the first and second
Next, re-drawing was performed to obtain a thin-walled deep-drawing cup. The molding conditions in the redrawing step and various characteristics of the redrawn deep drawn cup are shown below. Primary redraw ratio 1.23 Secondary redraw ratio 1.24 Redraw die working corner radius of curvature 0.30mm Redraw die holding corner radius of curvature 1.0mm Cup diameter 66mm Cup height 130mm Side wall thickness change rate -40% After performing doming molding according to a conventional method, the deep drawing cup was heat-treated at 215 ° C. for 1 minute to remove processing distortion of the film and volatilize the lubricant. Next, the end of the 66 mm opening was reduced to 57 mm by a roll neck method, and flanged to obtain a 350 ml thin seamless can having an outer side wall area of 235 cm 2. Table 5 shows the evaluation results.

<Example 21> A film biaxially stretched with the composition shown in Table 1 (stretching ratio: 3.0 times in length, 3.0 times in width)
A metal can was formed in the same manner as in Example 1 except that (2) was used. Table 5 shows the evaluation results.

<Example 22> As a metal substrate, a sheet thickness of 0.2
A metal can was formed in the same manner as in Example 1 except that a 26 mm aluminum alloy plate (A3004H39 material) was used. Table 5 shows the evaluation results.

<Example 23> TFS heated to 250 ° C
Steel plate (sheet thickness 0.18mm, metallic chromium amount 120mg / m
2, chromium hydrated oxide amount 15 mg / m2), dry-blended a resin having the composition shown in Table 1, supplied to a 65 mm extruder equipped with extrusion lamination equipment, and melted to a thickness of 20 µm. Extrude and T
The FS was laminated on one side. Next, the same resin component was added to φ6 with an extrusion lamination facility.
After feeding the extruder to a 5 mm extruder, the plate temperature was set at 3
It was heated to a temperature lower by 0 ° C., melt-extruded to a thickness of 20 μm, and laminated on the other surface. Next, a metal can was formed in the same processing step as in Example 1.
Table 5 shows the evaluation results.

<Example 24> As a metal substrate, a sheet thickness of 0.2
A metal can was formed in the same manner as in Example 24, except that a 26 mm aluminum alloy plate (A3004H39 material) was used. Table 5
Figure 11 shows the evaluation results.

<Examples 25 and 26> An aluminum alloy (A5052H3) having a thickness of 0.25 mm heated to 250 ° C.
8), and the resin having the composition shown in Table 1 was dry-blended and supplied to a φ65 mm extruder equipped with an extrusion lamination equipment, and was melt-extruded to a thickness of 20 μm and laminated on one side of TFS. did. Next, after supplying the same resin component to a φ65 mm extruder equipped with an extrusion lamination facility, the plate temperature was heated to a temperature 30 ° C. lower than the melting point of the resin, and the thickness was 20 μm.
m and then laminated on the other side. With respect to the obtained resin-coated metal plate, a lid having a diameter of 68.7 mm is punched so that the resin-coated surface is on the inner side of the lid, and then a partial opening type score processing (22 mm in width, 110 μm in remaining score thickness) is performed on the outer side of the lid. (Score width: 20 μm), rivet processing and attachment of an opening tab, and an attempt was made to produce an SOT lid. As a result, a practically favorable molding was achieved. Next, the prepared SOT lid was replaced with Example 1
When a dent test and a retort resistance test were performed in combination with the metal can prepared in the above, no occurrence of corrosion was observed in any case, and practical performance as a container was obtained.

Comparative Examples 1 to 6 A metal can was molded in the same manner as in Example 1 except that a polyester film having the composition shown in Table 1 was used. Table 5 shows the evaluation results.

Comparative Example 7 Examples 21 and 22 were conducted except that a polyester film having the composition shown in Table 1 was used.
In the same manner as above, molding of a metal can was attempted. Table 5 shows the evaluation results.

<Comparative Example 8> An attempt was made to fabricate an SOT lid in the same manner as in Example 26 except that a polyester film having the composition shown in Table 1 was used. As a result, apparently good molding was possible. In a dent test and a retort resistance test, remarkable corrosion occurred, and practical performance as a container was poor.

[0098]

[Table 1]

[0099]

[Table 2]

[0100]

[Table 3]

[0101]

[Table 4]

[0102]

[Table 5]

[0103]

According to the present invention, in a resin-coated metal plate comprising a metal substrate and a thermoplastic polyester layer provided on the surface of the substrate, the thermoplastic polyester layer comprises thermoplastic polyester and 0.05% per polyester. By using a resin containing a modified polyester layer composed of a composition of about 25% by weight to 25% by weight of epoxy resin, high-temperature, high-temperature, wet-heat resistance that can withstand retort sterilization and impact resistance can be significantly improved. . This resin-coated metal plate is particularly suitable for the production of metal cans and can lids, since the adhesion of the coating resin layer to the metal substrate is further improved, and furthermore, it has the workability for high-speed can manufacturing. .

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view showing an example of a sectional structure of a resin-coated metal plate used in the present invention.

FIG. 2 is an enlarged sectional view showing another example of the sectional structure of the resin-coated metal plate used in the present invention.

FIG. 3 is an explanatory view showing an example of a manufacturing process of a resin-coated metal plate.

FIG. 4 is an explanatory view showing a bending / stretching / ironing step used for manufacturing a metal can.

FIG. 5 is a top view showing an example of an easy open can lid according to the present invention.

FIG. 6 is an enlarged sectional view showing an enlarged section of the can lid of FIG. 5;

[Description of Signs] 1 Resin-coated metal plate 2 Metal substrate 3 Modified polyester layer 4 Thermoplastic polyester layer 5 Polyester surface layer 6 Laminated resin layer 11 Metal plate 12a, 12b Heating roll 13 Chill roll 14 Nip roll 15 Die head 16 Thin film 17 Laminate 30 Front drawing cup 31 Holding member 32 Ironing die 33 Ironing punch 34 Flat part 35 Working corner part 36 Approach part 37 Curvature part 38 Land part 40 Outer peripheral surface 41 Curvature corner part 42 Annular bottom surface 50 Lid 51 Annular rim part 52 Sealing groove 53 Opening Shoulder 54 Score 55 Rivet 56 Tab for opening 57 Tip for opening 58 Retaining ring 59 Supporting point

Claims (11)

[Claims] 1. A resin-coated metal plate comprising a metal substrate and a thermoplastic polyester layer provided on the surface of the substrate, wherein the thermoplastic polyester layer comprises at least a thermoplastic polyester and 0.05 to 2 per polyester.
A resin-coated metal plate comprising a modified polyester layer comprising a composition with 5% by weight of an epoxy resin. 2. The resin coating according to claim 1, wherein the thermoplastic polyester in the composition is a polyester derived from a carboxylic acid component mainly composed of an aromatic dicarboxylic acid and an alcohol component mainly composed of an aliphatic diol. Metal plate. 3. The resin-coated metal plate according to claim 2, wherein at least 50 mol% of the carboxylic acid component is composed of a terephthalic acid component and at least 50 mol% of the alcohol component is composed of an ethylene glycol component. 4. The method according to claim 1, wherein the epoxy resin is 150 to 5000.
The resin-coated metal plate according to any one of claims 1 to 3, which has an epoxy equivalent of the following. 5. The epoxy resin according to claim 1, wherein the epoxy resin is an epoxy resin derived from bisphenols and epihalohydrin, an epoxy resin derived from novolaks and epihalohydrin, or a modified product thereof. Resin coated metal plate. 6. The resin-coated metal plate according to claim 1, wherein the epoxy resin is a resin obtained by copolymerizing or graft copolymerizing an unsaturated epoxy compound. 7. The modified polyester layer according to claim 1, wherein the modified polyester layer further contains at least one modified resin component selected from the group consisting of an ethylene polymer, a thermoplastic elastomer, a polyarylate and a polycarbonate. Resin coated metal plate. 8. The resin-coated metal sheet according to claim 7, wherein the resin-modifying component is contained in an amount of up to 50% by weight per thermoplastic polyester. 9. The resin-coated metal plate according to claim 1, wherein the modified polyester layer is located at least on a side in contact with the metal substrate. 10. A metal can formed from the resin-coated metal plate according to claim 1. 11. A can lid formed from the resin-coated metal plate according to claim 1.