JP2001347605A - Resin-coated metallic sheet, metallic can and can lid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin-coated metallic sheet which has resistance to high temperatures, and heat and humidity capable of enduring retort sterilization and a period of time passed thereafter, and has excellent shock resistance under severe conditions such as the retort sterilization, hot vender or the like, and also has processability capable of enduring advanced can manufacturing, and to provide a metallic can and a can lid composed of the resin-coated metallic sheet. SOLUTION: The resin-coated metallic sheet comprises a metal base and a thermoplastic polyester resin layer formed on the surface of the metal base. The thermoplastic polyester layer on the side of the metal base at least contains a dimer acid component of 1 to 15 mol% as a dicarboxylic acid component, and a butylene glycol component of 5 to 70 mol% as a diol component. A surface orientation coefficient of the thermoplastic polyester layer is 0.05 or smaller.

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 having a metal substrate coated with a polyester resin, and more particularly, to an unoriented polyester film containing a polyester resin containing dimer acid and butylene glycol. The present invention relates to a resin-coated metal plate having excellent workability, high-temperature wet-heat resistance, and impact resistance by laminating the resin-coated metal plate on a metal substrate, 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 side seamless can (seamless can) is obtained by subjecting a metal material such as an aluminum plate, a tin plate or a tin-free steel plate to at least one-step drawing between a drawing die and a punch. To form a cup consisting of a body part having no side seam and a bottom part integrally connected to the body part, and then, if desired, bending or stretching (stretching) the body part by ironing or drawing. ) Is known in which the side wall is thinned.
As an organic coating method for such a side seamless can, a method of laminating a resin film in advance on a metal material before molding has been known.
No. 56 describes that a polyester film having an intrinsic viscosity [η] of 0.75 or more is used for a metal laminate.

[0003] 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 still a need for further improvement in the adhesion of the resin coating layer to the metal substrate and further improvement in workability for high-speed can making. In order to further improve the storage stability of the contents to be filled,
It is an important technical subject to improve high-temperature, high-humidity and heat resistance to withstand retort sterilization and subsequent aging, to improve impact resistance after retort sterilization, and to improve corrosion resistance after retort sterilization and impact.

[0004]

As a material which satisfies both impact resistance and moldability, an A layer made of polyester A containing ethylene terephthalate or ethylene naphthalate as a main component, a polyester B1 and a carbon number of 1
A polyester B2 obtained by copolymerizing a long-chain aliphatic dicarboxylic acid component having 0 or more alkylene groups;
And a long-chain aliphatic dicarboxylic acid component having an alkylene group having 10 or more carbon atoms.
A laminated film for laminating a metal plate containing 2 to 20% by weight in a layer has been proposed (Japanese Patent Laid-Open No. 9-1504).
No. 92).

[0005] However, even if a metal plate coated with the above-mentioned laminated film can ensure a certain degree of excellent formability and impact resistance, such a stretched laminated material can withstand a high degree of drawing, stretching or ironing. It was not something. In addition, in metal cans by stretch processing and / or ironing, weight reduction is achieved by further reducing the thickness of the can body in order to reduce costs.
Along with the thinning of the can body, the resin coated on the metal plate is required to have higher workability, and a resin-coated metal plate capable of withstanding high processing is required. In general, highly processed cans require more processing, and can be used for negative pressure cans with relatively small distortion, but are insufficient for positive pressure cans with large distortion.

Accordingly, an object of the present invention is to provide high-temperature, high-humidity heat resistance to withstand retort sterilization and subsequent aging, and to provide excellent impact resistance even when subjected to severe conditions such as retort sterilization and hot bender. Another object of the present invention is to provide a resin-coated metal plate having a workability capable of withstanding a high degree of can-making and a metal can and a can lid made of the resin-coated metal plate.

[0007]

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, at least the thermoplastic polyester layer on the metal substrate side is a dicarboxylic acid. 1 to 15 mol% of a dimer acid component as a component and 5 to 70 mol% of a butylene glycol component as a diol component
A resin-coated metal plate is provided, wherein the thermoplastic polyester layer has a plane orientation coefficient of less than 0.05.

[0008] In the resin-coated metal plate of the present invention: The thermoplastic polyester layer is composed of a laminate of at least two layers of a thermoplastic polyester layer on the metal substrate side and a thermoplastic polyester layer on the surface side, and the thermoplastic polyester layer on the surface side is composed of an aromatic dicarboxylic acid and a diol. 1. a derived polyester; 2. the thermoplastic polyester is formed on a metal substrate by melt extrusion coating; It is preferable that the thermoplastic polyester is formed on a metal substrate by thermal bonding of a cast film formed in advance. According to the present invention, there is also provided a metal can and a can lid formed from the resin-coated metal plate.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The resin-coated metal plate of the present invention contains 1 to 15 mol% of a dimer acid component as a dicarboxylic acid component and 5 to 70 mol% of a butylene glycol component as a diol component, and has a plane orientation coefficient. It is characterized in that a thermoplastic polyester smaller than 0.05 is coated on a metal substrate, whereby it is resistant to retort sterilization and high temperature and heat resistance to withstand aging over time, and excellent under severe conditions such as retort sterilization and hot bender. Thus, it has become possible to have characteristics such as impact resistance, formability and workability that can withstand advanced can-making.

The dimer acid component, which is essential as the dicarboxylic acid component of the polyester used in the present invention, is excellent in high-temperature wet heat resistance. By containing it in an amount of 1 to 15 mol%, it can withstand retort sterilization and subsequent aging. This makes it possible to impart high-temperature, high-humidity heat resistance to a resin-coated metal plate or a metal can and a can lid formed from the resin-coated metal plate. In the present invention, the dimer acid component is 1
It is particularly important that the content is in the range of from about 15 to about 15 mol%, particularly from about 2 to about 10 mol%. When the dimer acid content is lower than the above range, the moldability and processability are inferior, and when the dimer acid content is higher than the above range, the high-temperature wet heat resistance becomes insufficient.

The butylene glycol component, which is essential as a diol component of the polyester used in the present invention, is excellent in impact resistance. By containing it in an amount of 5 to 70 mol%, severe refractory such as retort sterilization or hot bender is required. Even under such conditions, excellent impact resistance can be imparted to the resin-coated metal plate, or the metal can and can lid formed from the resin-coated metal plate. In the present invention, the butylene glycol component is 5 to 70.
It is particularly important that it be contained in an amount of from about 10 to about 60 mol%. When the butylene glycol content is less than the above range, it is not possible to sufficiently improve the impact resistance obtained by containing butylene glycol, and when the butylene glycol content is higher than the above range. In this case, the moldability becomes inferior.

Further, the polyester coating layer used in the present invention has the following formula (1): ns = [(nx + ny) / 2] -nz (1) In the formula, in the direction parallel to the substrate rolling using an Abbe refractometer. The refractive index is nx, the perpendicular direction is ny, and the thickness direction is nz.
It is an important feature that the plane orientation coefficient obtained by the above is smaller than 0.05. When the plane orientation coefficient is smaller than 0.05, workability and formability can be improved. That is, generally, when a film is stretched and oriented, mechanical strength such as tensile strength is improved, but elongation at break is reduced. Therefore, when subjected to severe processing such as drawing, stretching, ironing, etc., the non-oriented film which has not been oriented does not cause film breakage due to the processing, and the workability and formability are improved. Considered excellent. Therefore, in the present invention, the plane orientation coefficient is smaller than 0.05, that is, by using an amorphous and non-oriented polyester as the coating layer, it becomes possible to impart excellent moldability that can withstand advanced processing. It is.

In the present invention, the dicarboxylic acid component contains 1 to 15 mol% of a dimer acid component, the diol component contains 5 to 70 mol% of a butylene glycol component, and a thermal orientation coefficient smaller than 0.05. The plastic polyester only needs to be provided on at least the surface of the metal substrate on the inner surface side of the metal substrate in which workability and the like are problematic, and may be provided in a single layer or in multiple layers. In the case of providing a multilayer, a thermoplastic polyester layer containing a certain amount of dimer acid as a carboxylic acid component and butylene glycol as a diol component is used as a base resin layer on the metal substrate side, and is derived from an aromatic dicarboxylic acid and a diol. It is particularly preferable to form a laminate of at least two layers in which the layer made of the polyester thus obtained is used as the surface resin layer on the front side. Polyesters derived from aromatic dicarboxylic acids and diols have low adsorption of aromatic components in the contents and are excellent in barrier properties against corrosive components. This is because it is preferable from the viewpoint of the retention and the like.

(Thermoplastic polyester resin) In the present invention, the dimer acid used as the dicarboxylic acid component is
It is obtained by dimerizing an unsaturated fatty acid having 10 to 25 carbon atoms. Examples of the unsaturated fatty acid include linoleic acid, linolenic acid, oleic acid, palmitooleic acid, elaidic acid, arachidonic acid, and erucic acid. And the like. In addition, a linear branched structure, an alicyclic structure, and an aromatic nucleus structure are generated during the dimerization reaction, and the content of the alicyclic structure and / or the aromatic nucleus structure is 50 mol% or more of the entire dimer acid. Is preferred. Examples of the dicarboxylic acid component other than dimer acid include terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, p-β-oxyethoxybenzoic acid, biphenyl-4,4′-dicarboxylic acid, diphenoxyethane-4,4′-dicarboxylic acid Aromatic dicarboxylic acids such as sulfonic acid, oxalic acid, succinic acid, adipic acid, sebacic acid, maleic acid, fumaric acid, trimellitic acid, pyromellitic acid and the like, 5-sodium sulfoisophthalic acid and hexahydroterephthalic acid Can be mentioned.

On the other hand, diol components other than butylene glycol include ethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol, 1,6-hexylene glycol, diethylene glycol, triethylene glycol, cyclohexanedimethanol, and bisphenol. A ethylene oxide adduct,
Glycerol, trimethylolpropane, pentaerythritol, dipentaerythritol, sorbitan and the like can be mentioned.

In the present invention, the thermoplastic polyester containing 1 to 15 mol% of dimer acid as a dicarboxylic acid component and 5 to 70 mol% of butylene glycol as a diol component is a polyester having a composition other than the above components. It may be a blend or a copolyester. The thermoplastic polyester should have a molecular weight in the range of film formation and an intrinsic viscosity [η] measured using a phenol / tetrachloroethane mixed solvent as a solvent of 0.5 or more, especially 0.6 to 1.
The range of 5 is good in terms of barrier properties against corrosive components and mechanical properties.

When a layer composed of the above-mentioned thermoplastic polyester is used as a base resin layer and another thermoplastic polyester is laminated thereon as a surface resin layer, various thermoplastic polyesters composed of the above-mentioned dicarboxylic acid component and diol component may be used. As described above, a polyester derived from an aromatic dicarboxylic acid and a diol is particularly preferable. Among them, a terephthalic acid component is contained as an aromatic dicarboxylic acid component in an amount of 50 mol% or more, and a diol component is contained. It is particularly preferable to use a thermoplastic polyester mainly composed of ethylene terephthalate containing 50 mol% or more of ethylene glycol.

(Metal Substrate) As the metal plate used in the present invention, various surface-treated steel plates and light metal plates such as aluminum are used. As a 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. Further, an aluminum-coated steel sheet subjected to aluminum plating, aluminum rolling, or the like is used. As a light metal plate, an aluminum alloy plate is used in addition to a so-called pure aluminum plate. The original thickness of the metal plate varies depending on the type of metal, the use or size of the container, but it is generally preferable to have a thickness of 0.10 to 0.50 mm. The thickness is preferably 10 to 0.30 mm, and in the case of a light metal plate, 0.15 to 0.40 mm.

(Resin-Coated Metal Plate and Its Manufacturing Method) FIG.
1 shows an example of a cross-sectional structure of a resin-coated metal plate of the present invention. This resin-coated metal plate 1 includes a metal substrate 2 and dimer acid and butylene glycol provided on the inner side when the container is formed. And a layer 3 made of a thermoplastic polyester as an essential component. A thermoplastic polyester layer 4 is also formed on the outer surface side of the container of the metal substrate 2, and the polyester layer on the outer surface side may be made of a thermoplastic polyester containing dimer acid and butylene glycol as essential components, or other than that. May be composed of a polyester coating layer. In FIG. 2 showing another example of the resin-coated metal substrate, a base layer 3 made of a thermoplastic polyester containing dimer acid and butylene glycol as essential components located on the side which is in contact with the metal substrate is provided on the side serving as the inner surface of the container. It is the same as FIG. 1 except that a laminated resin layer 6 of a surface layer 5 made of a polyester derived from an aromatic dicarboxylic acid and a diol is provided.

In the present invention, the polyester coating layer preferably has a thickness of 1 to 60 μm, especially 2 to 40 μm as a whole in terms of balance between protection of the metal substrate and workability. The layer composed of the thermoplastic polyester containing acid and butylene glycol as essential components and the other polyester layer are present in a thickness ratio of 1:40 to 40: 1, particularly in a thickness ratio of 1:20 to 20: 1. This is preferable in terms of balance with workability, high-temperature wet heat resistance, impact resistance, and the like.

In the present invention, the formation of the polyester coating layer on the metal substrate can be carried out by any means, but is particularly preferably carried out by a melt extrusion coating method or a cast film heat bonding method. 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, and the polyester is extrusion-coated in a molten state on a metal substrate and thermally bonded. In the case of the extrusion coating method, a polyester film is formed and can be directly laminated without being biaxially stretched.
The value can be set to a value smaller than 05, and various steps can be omitted to increase the productivity. When a polyester film is used, a film formed by a T-die method or an inflation film forming method is thermally bonded to a metal substrate. In particular, by using an unstretched film obtained by quenching the extruded film and casting, the plane orientation coefficient can be reduced to a value smaller than 0.05, and the polyester film is formed in a film forming step or a laminating step. There is an advantage that the degree of thermal degradation is small. .

In the present invention, various configurations other than the above-mentioned layer configuration can be adopted, and a conventionally known bonding primer can be provided between the metal substrate and the polyester layer. This adhesive primer exhibits excellent adhesiveness to both the metal material and the film. As a primer paint excellent in adhesion and corrosion resistance, a resole type phenol aldehyde resin derived from various phenols and formaldehyde, and a phenol epoxy type paint composed of a bisphenol type epoxy resin,
Particularly, it is a paint containing a phenol resin and an epoxy resin in a weight ratio of 50:50 to 1:99, particularly 40:60 to 5:95. The adhesive primer layer is generally preferably provided with a thickness of 0.01 to 10 μm. The adhesive primer layer may be provided on a metal material in advance, or may be provided on a polyester film.

(Metal can and its manufacturing method) The metal can made of the resin-coated metal plate of the present invention may be of 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 with side seams, but is generally preferably a seamless can. This seamless can, so that the coated surface of the polyester composition of the resin-coated metal plate described above is the inner surface of the can,
It is manufactured by applying conventionally known means such as drawing / redrawing, drawing / stretching, drawing / stretching / ironing or drawing / ironing. Although the metal can of the present invention is manufactured by the above-mentioned means, it is preferable to reduce the thickness of the side wall portion by preferably performing a stretching process and / or an ironing process. The thickness of the resin-coated metal plate is reduced by 20 to 95%, particularly 30 to 85% of the thickness of the resin-coated metal plate by stretching and / or ironing the side wall portion compared to the bottom portion.
% Is preferably thinned.

For example, according to drawing / stretching,
A pre-draw cup is formed from the resin-coated metal plate by drawing at a draw ratio of 1.1 to 3.0, and the cup is formed by a redraw punch and a redraw die at a draw ratio of 1.5 to 5.0. While performing redrawing, the radius of curvature (Rd) of the working corner of the redrawing die is set to be 1 to 2.9 times, particularly 1.5 to 2.9 times, the thickness of the metal plate (tB). By performing the bending and stretching, the thickness can be effectively reduced, the variation in the thickness between the lower portion and the upper portion of the side wall portion is eliminated, and the uniform thickness reduction can be achieved over the entire side wall portion. Generally, the side wall portion of the can body is made to have a plate thickness (t).
B) a thickness of not more than 80% on a basis, up to 45%, in particular 40%
It can be thinned to a thickness of up to. In the redrawing, an ironing portion may be arranged behind the bending and stretching portion of the redrawing die, and ironing may be performed on the side wall portion.

The following formula (2) RI = {(tB−tW) / tB} × 100 (2) where tB is the thickness of the base plate and tW is the thickness of the side wall portion by bending and ironing. It is. It is preferable to reduce the thickness so that the thickness reduction ratio RI defined by the following equation is 20 to 95%, particularly 30 to 85%.

The resulting can is subjected to at least one stage of heat treatment to remove residual strain of the film caused by processing.
The lubricant used in the processing is volatilized from the surface, and the printing ink printed on the surface is dried and hardened. 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.

(Can lid and its manufacturing method) The can lid made of the resin-coated metal plate of the present invention may be formed by any conventionally known lid manufacturing method as long as it is formed from the above-mentioned resin-coated metal plate. Generally, the present invention is applied to a stay-on-tab type easy-open lid and a full-open type easy-open lid.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to the following examples. [Preparation of resin-coated metal plate] Examples 1 to 6, Comparative Examples 1 to 3
About TFS steel sheet heated to 250 ° C.
18 mm, a chromium metal content of 120 mg / m ² and a chromium hydrated oxide content of 15 mg / m ² ) were dry-blended with a polyester resin having the composition shown in Table 1 so as to have the composition shown in Table 2, and extrusion lamination was performed. It was supplied to a φ65 mm extruder equipped with equipment, and was melt-extruded to a thickness of 20 μm on the outer surface side, and laminated on one side of TFS. Then, as the inner surface side, the same resin component was provided with an extrusion lamination facility φ
After feeding to a 65 mm extruder, the plate was heated to a temperature 30 ° C. lower than the melting point of the resin, melt-extruded to a thickness of 20 μm, and laminated on the other surface to obtain a resin-coated metal plate.

For Examples 7 to 9 and Comparative Example 4, see Table 2
The polyester resin having the composition shown in Table 1 was blended so as to have the composition shown in Table 1 and preliminarily mixed with a Henschel mixer. Then, the mixture was pulverized with a pin mill or the like and put into a twin-screw extruder to be melt-kneaded. The film extruded to a thickness of 20 μm was cooled by a cooling roll, and the obtained film was wound up to obtain a cast film. At this time, as the temperature condition, an optimum temperature condition suitable for each resin was selected. However, in Example 7, using two twin-screw extruders and a two-layer T-die, the resin C shown in Table 1 was used as a surface layer, and a two-layer cast film having a surface layer of 5 μm and a lower layer of 15 μm was produced. In Example 7, these cast films were prepared by using a TFS steel plate (sheet thickness 0.18 mm, chromium metal content 120 mg / m ² , chromium hydrated oxide content 15 mg /
m ² ), heat-laminated on both sides, and immediately cooled with water to obtain a resin-coated metal plate. At this time, the temperature of the metal plate before lamination is 15 ° C. from the melting point of the polyester resin.
Set high. The laminating roll temperature is 150
° C, the passing speed is 40 m / min. Was used for lamination.

In Example 8, a resin-coated metal plate was obtained in the same manner as in Example 7, except that an aluminum alloy plate (A3004H39 material) having a thickness of 0.24 mm was used. In Example 9, an aluminum alloy (A5
A resin-coated metal plate was obtained in the same manner as in Example 7, except that No. 052H38 material) was used. Comparative Example 4 was a resin-coated metal plate in the same manner as in Example 7, except that the prepared cast film was stretched three times vertically and horizontally at 100 ° C. and then heat-treated at 230 ° C. for 5 seconds. I got

[Plane Orientation Coefficient] A free film was isolated by dissolving metal from a resin-coated metal plate. Then at least two
After vacuum drying for 4 hours, the measurement was performed by the method described in the specification.

[High-Temperature Wet Heat Test] The metal was dissolved from the untreated resin-coated metal plate and the resin-coated metal plate that had been retorted at 135 ° C. for 30 minutes and then aged at 90 ° C. for 2 weeks in water to isolate a free film. Thereafter, vacuum drying was performed for at least 24 hours to obtain a sample. The molecular weight of the polyester was measured by GPC using a conventional method, and the average molecular weight in terms of polystyrene was calculated. The molecular weight retention was calculated from the ratio of the average molecular weight after the lapse of time to the untreated average molecular weight, and was determined as high-temperature wet heat resistance. The evaluation results are shown as: A: retention of molecular weight> 70% X: retention of molecular weight <70% and summarized in Table 2.

[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 ° under wet conditions at 5 ° C. with the coated surface to be evaluated, and the opposite side sandwiching the metal plate. Put a 5/8 inch diameter steel ball in the
Weight was dropped from 40 mm to perform impact overhang processing. The degree of cracking of the resin film in the impact-processed portion was adjusted to 6.0
The current value at 0 V was measured, the average of six samples was taken, and the metal exposure by processing was evaluated. The evaluation results are shown as: A: average current value <0.1 mA X: average current value> 0.1 mA and summarized in Table 2.

[Adhesion test] The resin-coated metal plate was rolled to a thickness of 50% of the original thickness, and the rolled resin-coated metal plate was cross-cut with a cutter, and cellotape (Nichiban Co., Ltd.) (24 mm width), and the cellophane tape was peeled off. The evaluation was made from the state of peeling of the resin film after peeling off the cellophane tape. The evaluation results are shown in Table 2 as ○: no film peeling, ×: film peeling.

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

[Pack test] In the case of evaluation of a metal can, if the can filled with cola is left sideways, the can is placed at 5 ° C. on a can axis perpendicular to the rolling direction of the metal plate. Diameter 65.5mm at the end of the neck processing part on the bottom of the can
A 1 kg weight having a spherical surface was dropped from a height of 40 mm such that the spherical surface hits 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. When the evaluation was a lid, the can filled with cola was subjected to a storage test at a temperature of 37 ° C., and the state of the inner surface of the lid one year later was observed.

<Examples 1 to 7> The prepared resin-coated metal plates were subjected to a high-temperature wet heat test, a flat plate dent ERV test, and an adhesion test. Table 2 summarizes the results. All the resin-coated metal sheets were excellent in high-temperature wet heat resistance, dent resistance, and adhesion. A wax-based lubricant was applied to these resin-coated metal plates, and a disk having a diameter of 166 mm was punched to obtain a shallow drawn cup. Next, the shallow drawn cup was stretched to obtain a seamless cup. The characteristics of this seamless cup were as follows. Cup diameter: 66 mm, cup height: 128 mm, can wall thickness 65% based on blank thickness, flange thickness 77% based on blank thickness.

This seamless cup is subjected to doming molding by a conventional method, heat-treated at 220 ° C., and after allowing the cup to cool, trimming the edge of the opening, printing on a curved surface, and baking. Then, a neck process and a flange process were performed to obtain a seamless can for 350 g. There was no problem on molding. Next, it was subjected to a pack test and a retort treatment test by filling with distilled water. As shown in Table 2, the dent portion corrosion in the pack test and the occurrence of corrosion in the retort test were not recognized, and were good. From these results, the seamless cans obtained here were evaluated as being excellent for storing beverages.

Example 8 The prepared resin-coated metal plate was subjected to a high-temperature wet heat test, a flat plate dent ERV test, and an adhesion test. Table 2 summarizes the results. All the resin-coated metal sheets were excellent in high-temperature wet heat resistance, dent resistance, and adhesion. A wax-based lubricant was applied to these resin-coated metal plates, and a disk having a diameter of 152 mm was punched to obtain a shallow drawn cup. Next, the shallow drawn cup was stretched and ironed to obtain a seamless cup. The characteristics of this seamless cup were as follows. Cup diameter: 66 mm, cup height: 127 mm, can wall thickness 45% based on blank thickness, flange thickness 77% based on blank thickness.

This seamless cup is subjected to doming molding according to a conventional method, heat-treated at 220 ° C., and after allowing the cup to cool down, trimming the edge of the opening, printing a curved surface, and printing and baking. Processing and flange processing were performed to obtain a seamless can for 350 g. There was no problem on molding. Next, it was subjected to a pack test and a retort treatment test by filling with distilled water. As shown in Table 2, the dent portion corrosion in the pack test and the occurrence of corrosion in the retort test were not recognized, and were good. From these results, the seamless cans obtained here were evaluated as being excellent for storing beverages.

Example 9 The prepared resin-coated metal plate was subjected to a high-temperature wet heat test, a flat plate dent ERV test, and an adhesion test. Table 2 summarizes the results. All the resin-coated metal sheets were excellent in high-temperature wet heat resistance, dent resistance, and adhesion. Next, a lid having a diameter of 68.7 mm was punched out of the resin-coated metal plate so that the resin-coated surface was on the inner side of the lid, and then a partial opening type score processing (width 22) was performed on the outer side of the lid.
mm, score remaining thickness 110 μm, score width 20 μm), rivet processing and attaching an opening tab
Production of a T lid was performed. There was no problem on molding. Next, using the prepared SOT lid, a pack test and a retort resistance test were performed. No corrosion was observed in any case,
It was evaluated as an excellent lid for a metal can.

Comparative Example 1 The prepared resin-coated metal sheet was subjected to a high-temperature wet heat test, a flat plate ERV test, and an adhesion test. Table 2 summarizes the results. The dent resistance and adhesion were inferior to those of the examples. Using the resin-coated metal plate, an attempt was made to produce a seamless can under the same conditions as in Examples 1 to 7. However, during the formation of the cup, the film was broken and delamination occurred. Could not be obtained.

Comparative Example 2 The prepared resin-coated metal plate was subjected to a high-temperature wet heat test, a flat plate dent ERV test, and an adhesion test. Table 2 summarizes the results. The adhesion was inferior to that of the examples. Using the resin-coated metal plate, an attempt was made to produce a seamless can under the same conditions as in Examples 1 to 7. However, during the formation of the cup, the film was broken and delamination occurred. Could not be obtained.

Comparative Example 3 The prepared resin-coated metal plate was subjected to a high-temperature wet heat test, a flat plate dent ERV test, and an adhesion test. Table 2 summarizes the results. The high-temperature wet heat properties were inferior to those of the examples. Using this resin-coated metal plate, a seamless can was produced under the same conditions as in Examples 1 to 7. There was no problem on molding. Next, it was subjected to a pack test and a retort treatment test by filling with distilled water. As shown in Table 2, corrosion in the pack test and occurrence of corrosion in the retort test were observed. From these results, the seamless can obtained here was evaluated as unsuitable for storing beverages.

Comparative Example 4 The prepared resin-coated metal sheet was subjected to a high-temperature wet heat test, a flat plate dent ERV test, and an adhesion test. Table 2 summarizes the results. The adhesion was inferior to that of the examples. Further, using this resin-coated metal plate, an attempt was made to produce a seamless can under the same conditions as in Examples 1 to 7, but in the middle of deep cup molding, film breakage, delamination occurred, and Could not be obtained.

[0046]

[Table 1]

[0047]

[Table 2]

[0048]

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, at least the thermoplastic polyester layer on the metal substrate side has dimer acid as a dicarboxylic acid component. 1 to 15 mol% of the diol component and 5 to 70 mol% of the butylene glycol component as the diol component, and the plane orientation coefficient of the thermoplastic polyester layer is 0.1 to 0.1 mol%.
By being smaller than 05, it has high temperature and humidity resistance to withstand retort sterilization and subsequent aging, and has excellent impact resistance even when subjected to harsh conditions such as retort sterilization and hot bender. It has become possible to provide a resin-coated metal plate having processability that can withstand the can making process.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a cross-sectional structure of a resin-coated metal plate of the present invention.

FIG. 2 is a view showing another example of the cross-sectional structure of the resin-coated metal plate of the present invention.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) // B29K 67:00 B29K 67:00 B29L 7:00 B29L 7:00 F term (reference) 3E062 AA04 AB02 AC09 4F100 AB01A AJ11 AK41B AK41C BA02 BA03 BA06 BA07 BA10A BA10C EC03 EC032 EH23 EH232 GB16 GB18 JA20B JB16B JB16C JJ03 JK10 JL01 YY00B 4F207 AA24 AD03 AD05 AG03 AH55 AH57 KA01 KB13 KF01 KJ09 AKKA4A03 A03A03 A03A03 A03A03 A03A03 BA02 BA03 BA04 BA05 BA10 BB13A BD06A BD07A BF09 BF18 CA01 CA02 CA04 CA06 CB05A CB06A CC05A CD04 CF15 FC03 FC05 FC07 FC08 FC12 FC36 FC38 GA13 GA14 GA41 GA74 HA01 HB01 JF511 KB02 KD02 KE03

Claims (6)

[Claims] 1. A resin-coated metal plate comprising a metal substrate and a thermoplastic polyester layer provided on the surface of the substrate, wherein at least the thermoplastic polyester layer on the metal substrate side has 1 to 15 mol of a dimer acid component as a dicarboxylic acid component. %. The resin-coated metal sheet contains 5 to 70 mol% of a butylene glycol component as a diol component, and the thermoplastic polyester layer has a plane orientation coefficient of less than 0.05. 2. The thermoplastic polyester layer comprises a laminate of at least two layers, a thermoplastic polyester layer on the metal substrate side and a thermoplastic polyester layer on the surface side, wherein the thermoplastic polyester layer on the surface side is an aromatic dicarbonate. The resin-coated metal plate according to claim 1, which is a polyester derived from an acid and a diol. 3. The resin-coated metal plate according to claim 1, wherein the thermoplastic polyester is formed on a metal substrate by melt extrusion coating. 4. The resin-coated metal plate according to claim 1, wherein the thermoplastic polyester is formed on a metal substrate by thermal bonding of a cast film formed in advance. 5. A metal can formed from the resin-coated metal plate according to claim 1. 6. A can lid made of the resin-coated metal plate according to claim 1. Description: