JP3714177B2 - Film laminated metal plate for containers - Google Patents

Description

【００５５】
【表２】

【００５６】
表１および表２に示すように、本発明範囲の発明例は、いずれも内容物取り出し性、成形性、密着性、耐衝撃性及び味特性が良好な特性を示した。
【００５７】
本発明例において、ワックス成分としてカルナウバろう若しくはステアリン酸エステルを含有するものは内容物取り出し性がより優れる。フィルムの複屈折率の値が０．０２以下である領域が金属板との接触界面から厚さが５μｍ未満であると成形性がより優れる。緩和時間Ｔ１ρが２７０ｍｓｅｃ以上であると、成形性がより優れる。フィルムを構成するポリエステル単位の９５質量％以上がエチレンテレフタレート単位であると、耐衝撃性、味特性がより優れている。
【００５８】
これに対し、本発明の範囲を外れる比較例は、内容物取り出し性、味特性、成形性の少なくとも１つが不良であった。
【００５９】
【発明の効果】
本発明によるラミネート金属板は、内容物取り出し性、成形性、密着性、耐衝撃性、味特性が良好であり、絞り加工等を行う容器用素材、特に食缶容器用素材として好適である。
【図面の簡単な説明】
【図１】金属板のラミネート装置の要部を示す図。
【符号の説明】
１ 金属板（クロムめっき鋼板）
２ 金属帯加熱装置
３ ラミネートロール
４ａ，４ｂ フィルム[0001]
BACKGROUND OF THE INVENTION
The present invention mainly relates to a film laminated metal plate used for a can body and a lid of a food can. More specifically, the present invention relates to a film-laminated metal plate for containers that has good moldability and adhesion in a can-making process, and is excellent in contents take-out properties and taste characteristics after filling the contents.
[0002]
[Prior art]
Conventionally, metal plates such as tin-free steel (TFS) and aluminum, which are materials for metal cans used in food cans, have been painted. The technique of applying this coating has a problem that not only the baking process is complicated, but also a long processing time is required and a large amount of solvent is discharged. In order to solve these problems, many methods for laminating a thermoplastic resin film on a heated metal plate have been proposed.
[0003]
Many of these proposals relate to the improvement of adhesion and formability between the film and the metal plate as the base material, and the technical idea is generally (1) the application of a film having a polar group (polyester resin, etc.). (For example, Japanese Patent Laid-Open No. 63-236640), (2) Increase in surface free energy represented by activation by treatment such as corona discharge on the film surface (for example, Japanese Patent Laid-Open No. 5-200961) ).
[0004]
When the laminate metal plate proposed above is used for food canning, there is a problem that when the contents are taken out from the container, the contents are firmly attached to the inner surface of the container, and the contents are difficult to take out. Since this problem is closely related to the consumer's willingness to purchase, it is extremely important to improve the ease of taking out the contents in order to secure the consumer's willingness to purchase. Nevertheless, no consideration has been given to improving the ease of taking out the contents.
[0005]
[Problems to be solved by the invention]
Therefore, in view of the above circumstances, the present invention aims to provide a film-laminated metal plate for a container that secures the content take-out property and has the moldability, adhesion, and taste characteristics required for container processing. To do.
[0006]
[Means for Solving the Problems]
As a result of intensive studies to solve the above-mentioned problems, the present inventors have added a wax component to a biaxially stretched polyester resin film in which the film structure is highly controlled without substantially containing an isophthalic acid component. And found that this goal is achieved. That is, the gist of the present invention is as follows.
[0007]
(1) A biaxially stretched polyester film having a melting point of 240 to 300 ° C., a carboxyl end group of 10 to 50 equivalents / ton, and substantially not containing an isophthalic acid component as an acid component, and the biaxially stretched polyester resin When the resin film B is a resin film containing a 0.10 to 2.0% wax component with respect to the resin by mass ratio, the surface of the metal plate that becomes the container inner surface after container molding A film-laminated metal plate for containers, wherein the resin film A is laminated on the surface of the resin film B and the metal plate on the outer surface side of the container.
[0008]
(2) The film-laminated metal sheet for containers according to (1) above, which contains carnauba wax or stearic acid ester as a wax component.
(3) The region where the birefringence of the resin film A and the resin film B after lamination is 0.02 or less is less than 5 μm in the film thickness direction from the contact interface with the metal plate. The film-laminated metal plate for containers according to 2.
[0009]
(4) In any one of the above (1) to (3), 95% by mass or more of the polyester units constituting the resin film A and the resin film B are ethylene terephthalate units and / or ethylene naphthalate units. The film-laminated metal plate for containers as described.
(5) The film-laminated metal plate for containers according to any one of (1) to (4) above, wherein the laminated resin film A and resin film B have a thickness direction refractive index of 1.500 or more. .
[0010]
(6) The resin film B is composed of at least two layers, and the resin film B contains 0.10 to 2.0% of a wax component with respect to the resin only in the uppermost layer in contact with the contents. The film-laminated metal plate for containers according to any one of (1) to ( 5 ), wherein
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
In the present invention, a polyester film is used for the film (resin film A, resin film B), and polyester has a melting point (melting peak temperature) in DSC of 240 to 300 ° C. from the viewpoint of improving taste characteristics. However, it is preferable that the melting point is 245 to 300 ° C, particularly preferably 246 to 300 ° C. In addition, in this invention, a taste characteristic means the grade by which the flavor of a content is not spoiled by the adsorption | suction to the film of the scent component of the contents of a can, or the elution from a film.
[0012]
Further, the film used in the present invention is required to have a carboxyl end group amount of 10 to 50 equivalents / ton in terms of good adhesion to a metal plate and good taste characteristics after retort. Since the carboxyl end group has polarity, when this amount is increased, the adhesion becomes good, but the flavor components of the contents are easily adsorbed and the taste characteristics become poor. If the carboxyl end group amount is less than 10 equivalents / ton, good adhesion cannot be obtained, and if it exceeds 50 equivalents / ton, taste characteristics deteriorate. A polyester having a carboxyl terminal group amount of 15 to 48 equivalents / ton, particularly preferably 15 to 45 equivalents / ton, is desirable because of excellent long-term storage stability.
[0013]
The polyester used in the present invention is required to contain substantially no isophthalic acid component as an acid component, but it has good taste characteristics after retort, and suppresses the generation of abrasion powder in the can manufacturing process. Thus, it is preferable to use ethylene terephthalate and / or ethylene naphthalate as the main constituent. The phrase “substantially free of isophthalic acid” means that isophthalic acid is not intentionally contained other than those inevitably mixed as impurities.
[0014]
A low molecular weight component with an insufficient degree of polymerization contained in the film is likely to elute into the contents of beverages and the like, thus deteriorating taste characteristics. By not containing the isophthalic acid component substantially in the polyester, the low molecular weight component with insufficient polymerization degree in the film is reduced, so that the low molecular weight component eluted in the content is reduced and the taste characteristics are deteriorated. Is prevented.
[0015]
The polyester mainly composed of ethylene terephthalate and / or ethylene naphthalate is a polyester in which 95% by mass or more of the polyester is composed of ethylene terephthalate and / or ethylene naphthalate. If it is 97% by mass or more, even if the contents are filled into a metal can for a long period of time, it is more preferable because the taste characteristics are good.
[0016]
On the other hand, other dicarboxylic acid components and glycol components may be copolymerized as long as the taste characteristics are not impaired. Examples of the dicarboxylic acid component include aromatic compounds such as diphenylcarboxylic acid, 5-sodium sulfoisophthalic acid, and phthalic acid. Dicarboxylic acid, oxalic acid, succinic acid, adipic acid, sebacic acid, dimer acid, maleic acid, aliphatic dicarboxylic acid such as fumaric acid, aliphatic dicarboxylic acid such as cyclohexanedicarboxylic acid, oxycarboxylic acid such as p-oxybenzoic acid Etc.
[0017]
On the other hand, examples of the glycol component include aliphatic glycols such as ethylene glycol, propanediol, butanediol, pentanediol, hexanediol, and neopentyl glycol, finger ring glycols such as cyclohexanedimethanol, and aromatics such as bisphenol A and bisphenol S. Examples include glycol, diethylene glycol, and polyethylene glycol. These dicarboxylic acid components and glycol components may be used in combination of two or more.
[0018]
Moreover, as long as the effect of this invention is not inhibited, you may copolymerize polyfunctional compounds, such as trimellitic acid, trimesic acid, a trimethylol propane.
[0019]
Components contained in a small amount in the polyester used in the present invention include diethylene glycol, polyethylene glycol, cyclohexanedimethanol, sebacic acid, dimer acid, and the like, and diethylene glycol, polyethylene glycol and the like are used in applications where taste characteristics are severe.
[0020]
Moreover, in this invention, it prescribes | regulates that the resin film (resin film B) which becomes a container inner surface side after container shaping | molding contains a 0.10-2.0% wax component with respect to resin by mass ratio. The reason why the wax component is added as an additive is (1) reducing the surface energy of the film and (2) imparting lubricity to the film surface. The effect of (1) makes it difficult for the content to adhere to the film, and the effect of (2) makes it possible to drastically improve the take-out property of the content by reducing the friction coefficient of the film surface.
[0021]
The reason for limiting the content to 0.10% or more is that when the content is less than 0.10%, the effects of the above (1) and (2) are poor, and the contents are not easily taken out. Also, the reason for limiting to 2.0% or less is that if it exceeds 2.0%, the content take-out property is almost saturated and a special effect cannot be obtained, and the film deposition technique is difficult. This is because the productivity is poor and the cost is increased.
[0022]
As the wax component to be added, organic and inorganic lubricants can be used, but organic lubricants such as fatty acid esters are desirable, and among them, carnauba wax (main component: CH), which is one of plant waxes and is a natural wax. ₃ (CH ₂ ) ₂₄ COO (CH ₂ ) ₂₉ CH 3, which also contains other components composed of various aliphatics and alcohols.) Or, stearic acid esters have the above-mentioned effects ( ₁ ) and ( ₂ ). In addition, it is suitable because it can be easily added to the film because of its molecular structure. In addition, the polyester film containing the above-described wax can be produced by a usual film forming method after blending a predetermined amount of wax with polyester.
[0023]
The above effects cannot be obtained by applying a wax component to the film surface. This is because food cans and the like are subjected to a retort treatment for sterilization after filling the contents, and the wax applied in advance to the surface is absorbed by the contents. When added to the film as in the present invention, the wax gradually thickens on the surface during the retort treatment, so that all of the above-mentioned effects can be reliably expressed without being absorbed by the contents. It becomes.
[0024]
Further, as the structure of the film after being laminated on the metal plate, it is desirable that the region having a birefringence of 0.02 or less be less than 5 μm in the film thickness direction from the contact interface with the metal plate. In the production of a laminated metal plate, the film is usually adhered to the film by bringing the film into contact with the heated metal plate and press-bonding to melt the film resin at the interface of the metal plate and wet the metal plate. Therefore, in order to ensure the adhesion between the film and the metal plate, the film needs to be melted, and the film birefringence of the portion in contact with the metal plate after lamination is inevitably lowered. .
[0025]
As specified in the present invention, if the film birefringence of this part is 0.02 or less, it indicates that the film melt wettability at the time of lamination is sufficient, and therefore it is possible to ensure excellent adhesion. .
[0026]
As the birefringence of such a polyester resin, a value obtained by the following measurement method is adopted. The retardation in the cross-sectional direction of the film after removing the metal plate of the laminated metal plate using a polarizing microscope is measured to determine the birefringence in the cross-sectional direction of the resin film. The linearly polarized light incident on the film is decomposed into two linearly polarized light in the main refractive index direction. At this time, the vibration of light in the high refractive index direction becomes slower than that in the low refractive index direction, so that a phase difference is generated when the film layer passes through. This phase difference is called retardation R, and the relationship with birefringence Δn is defined by equation (1).
[0027]
Δn = R / d (1)
However, d: thickness of film layer Next, a method for measuring retardation will be described. By passing the monochromatic light through the polarizing plate, it becomes linearly polarized light, and this light is incident on the sample (film). Since the incident light causes retardation as described above, it becomes elliptically polarized light after passing through the film layer. The elliptically polarized light passes through a Senarmon type compensator, and becomes linearly polarized light having an angle θ with respect to the vibration direction of the first linearly polarized light. This θ is measured by rotating the polarizing plate. The relationship between retardation R and θ is defined by equation (2).
R = λ · θ / 180 (2)
However, λ: birefringence Δn depending on the wavelength of monochromatic light is defined by equation (3) derived from equations (1) and (2).
Δn = (θ · λ / 180) / d (3)
Further, it is desirable that the thickness of the portion having a birefringence of 0.02 or less as described above is limited to a region of less than 5 μm in the film thickness direction from the contact interface with the metal plate. The reason for this is as follows.
[0028]
The film used in the present invention is characterized by low molecular mobility expressed by the relaxation time T1ρ of the carbonyl moiety in the structural analysis by solid high-resolution NMR, and thus has excellent moldability and impact resistance. When the film is completely melted, the effect thereof is poor, and there is a drawback that crystallization easily occurs in the subsequent processing and heat treatment, and the moldability of the film is deteriorated.
[0029]
However, in order to ensure film adhesion as described above, melt wetting of the film is essential. According to the results of intensive studies by the present inventors, the thickness of the melted portion of the film, that is, the portion where the birefringence of the film is 0.02 or less is regulated to less than 5 μm, thereby ensuring the adhesion and forming. And impact resistance can be achieved at a high level.
[0030]
The film used in the present invention needs to be biaxially stretched from polyester in terms of heat resistance and taste characteristics. The biaxial stretching method may be either simultaneous biaxial stretching or sequential biaxial stretching, but the stretching conditions and heat treatment conditions are specified, and the refractive index in the thickness direction of the film is 1.500 or more. Is preferable in terms of improving the laminating property and the drawability. Furthermore, if the refractive index in the thickness direction is 1.510 or more, particularly 1.520 or more, the surface orientation coefficient of the film after lamination can be improved in formability and impact resistance even if there is some temperature variation during lamination. It is preferable because it is possible to control the range of the plane orientation coefficient necessary for achieving both.
[0031]
In addition, the biaxially stretched polyester film used in the present invention is obtained by solid high-resolution NMR in terms of improving the formability when processing the neck portion after receiving a heat history of about 200 to 300 ° C. after drawing in the can making process. It is preferable that the relaxation time T1ρ of the carbonyl moiety in the structural analysis is 270 msec or more.
[0032]
Furthermore, the film used in the present invention preferably has a polyester thermal crystallization parameter ΔTcg (temperature rising crystallization temperature−glass transition temperature) of 60 ° C. or higher and 150 ° C. or lower in terms of improving moldability when processing the neck portion. Particularly preferably, it is 70 ° C. or higher and 150 ° C. or lower. Such a method for imparting thermal crystallinity can be achieved by controlling the catalyst, molecular weight, and diethylene glycol content.
[0033]
The configuration of the biaxially stretched polyester film used in the present invention may be a single layer or a multilayer. In the case of a multi-layer structure, it is necessary that a wax is added to the uppermost layer of the film (resin film B) in contact with the contents, and the wax is added only to the uppermost layer of the film from the viewpoint of economy. It is desirable that The thickness of the film is preferably 3 to 50 μm, more preferably 8 to 30 μm, in terms of formability after being laminated to a metal, coatability to metal, impact resistance, and taste characteristics.
[0034]
Although it does not specifically limit as a manufacturing method of film itself (a laminated film is included), For example, after drying each polyester as needed, individually and / or each is supplied to a well-known melt lamination extruder, and it is slit-shaped. The sheet is extruded from a die into a sheet, and is brought into close contact with a casting drum by a method such as electrostatic application, and is cooled and solidified to obtain an unstretched sheet.
[0035]
A biaxially stretched film is obtained by stretching this unstretched sheet in the longitudinal direction and the width direction of the film. The draw ratio can be arbitrarily set according to the degree of orientation, strength, elastic modulus, etc. of the target film, but is preferably a tenter method in terms of film quality, and after stretching in the longitudinal direction, A sequential biaxial stretching method of stretching in the width direction and a simultaneous biaxial stretching method of stretching the longitudinal direction and the width direction substantially the same are desirable.
[0036]
Next, a manufacturing method for laminating these films on a metal plate will be described. In the present invention, a method is used in which a metal plate is heated at a temperature exceeding the melting point of the film, and the resin film is brought into contact with both surfaces using a pressure-bonding roll (hereinafter referred to as a laminating roll) and laminated (heat fusion).
[0037]
The lamination condition is not particularly limited as long as the film structure specified in the present invention can be obtained. For example, the temperature at the start of lamination is preferably 280 ° C. or higher, and the temperature history received by the film at the time of lamination is preferably in the range of 1 to 20 msec. In order to achieve such lamination conditions, it is necessary to cool during bonding in addition to lamination at high speed. The pressure during lamination is not particularly specified, but the surface pressure is preferably 1 to 30 kgf / cm ² . If this value is too low, it is difficult to obtain sufficient adhesion because the time is short even if it is above the melting point. In addition, if the pressure is large, there is no problem in the performance of the laminated metal plate, but the force applied to the laminate roll is large and equipment strength is required, resulting in an increase in the size of the apparatus, which is uneconomical.
[0038]
As the metal plate, an aluminum plate or a mild steel plate that is widely used as a material for cans can be used. In particular, a surface-treated steel plate in which a two-layer film is formed in which the lower layer is made of metal chromium and the upper layer is made of chromium hydroxide. (So-called TFS) is optimal. The amount of adhesion of the metal chromium layer and chromium hydroxide layer of TFS is not particularly limited, but from the viewpoint of adhesion and corrosion resistance after processing, both are in terms of Cr, and the metal chromium layer is 70 to 200 mg / m ² , chromium. hydroxide layer is preferably in the range of 10 to 30 mg / m ^2.
[0039]
【Example】
Examples of the present invention will be described below.
A steel sheet that had been cold-rolled, annealed, and temper-rolled with a thickness of 0.18 mm and a width of 977 mm was degreased and pickled, and then chrome-plated to produce a chrome-plated steel sheet. The chromium plating was performed by chromium plating in a chromium plating bath containing CrO ₃ , F ⁻ , SO ₄ ²⁻ , intermediate rinsing, and then electrolyzed with a chemical conversion treatment solution containing CrO ₃ and F ⁻ . At that time, the electrolysis conditions (current density, amount of electricity, etc.) were adjusted to adjust the metal chromium adhesion amount to 120 mg / m ² and the chromium hydroxide adhesion amount to 15 mg / m ² .
[0040]
Next, using the metal band laminating apparatus shown in FIG. 1, the chrome-plated steel sheet 1 obtained above is heated by the metal band heating apparatus 2, and the container is formed on one surface of the chrome-plated steel band 1 by the laminating roll 3. As the resin film (resin film B) that will be the inner surface of the container later, various films 4a shown in Table 1 are laminated on the other surface, and various films 4b are laminated as the resin film (resin film A) that will be the outer surface of the container after container molding ( A laminated metal strip was manufactured by heat fusion). As the resin film 4a that becomes the inner surface of the container after forming the container, a resin film 4b that becomes the outer surface of the container is added with wax. The contents of the laminated resin film are shown in Table 1. The laminating roll 3 was an internal water-cooling type, and cooling water was forcibly circulated during the laminating to perform cooling during film adhesion.
[0041]
In addition, the characteristic of the used biaxially stretched polyester film is the following (1) to (5), and the characteristic of the laminated metal plate produced by the above method is the following (6) to (10). , Measured and evaluated. (1) to (4) are characteristics of the original film before lamination. The properties of (1), (3) and (4) remain unchanged after lamination.
[0042]
(1) Polyester carboxyl end-group polyester was dissolved in O-cresol / chloroform (mass ratio 7/3) at 90 to 100 ° C. for 20 minutes, and subjected to potentiometric titration with alkali.
[0043]
(2) Thickness direction refractive index sodium D line (wavelength 589 nm) of the film was used as a light source and measured using an Abbe refractometer.
(3) Melting point thermal crystallization parameter of polyester The polyester was dried, melted and rapidly cooled, and measured with a differential scanning calorimeter (DSC-2 type, manufactured by Perkin Elmer Co.) at a heating rate of 16 ° C / min.
[0044]
(4) Relaxation time T1ρ by solid high-resolution NMR
As a solid-state NMR measurement apparatus, a JEOL spectrometer JNM-GX270, a JEOL solid-state amplifier, a MAS controller NM-GSH27MU, and a JEOL probe NM-GSH27T were used. The measurement was carried out by measuring T1ρ (longitudinal relaxation in rotating coordinates) of ¹³ C nuclei. The measurement is performed under a temperature of 24.5 ° C., a humidity of 50% RH, and a static magnetic field strength of 6.34 T (Tesla), and the resonance frequencies of ¹ H and ¹³ C are 270.2 MHz and 67.9 MHz, respectively. In order to eliminate the influence of anisotropy of chemical shift, the MAS (magic angle rotation) method was adopted. The number of revolutions was 3.5 to 3.7 kHz. The pulse sequence conditions were 90 ° with respect to ¹ H, a pulse width of 4 μsec, and a rocking magnetic field strength of 62.5 kHz. The contact time of CP (cross polarization) for transferring the polarization of ¹ H to ¹³ C is 1.5 msec. Moreover, 0.001, 0.5, 0.7, 1, 3, 7, 10, 20, 30, 40, 50 msec was used as the holding time τ. The free induction decay (FID) of the ¹³ C magnetization vector after the holding time τ was measured (high power coupling was performed to eliminate the influence of dipole interaction due to ¹ H during FID measurement. S / N) In order to improve the accuracy, 512 integrations were performed). The pulse repetition time was 5 to 15 seconds.
[0045]
The T1ρ value can usually be described as I (t) = Σ (Ai) exp (−t / T1ρi), and the peak intensity observed for each holding time is semilogarithmically plotted to obtain the slope. I can find it. However, it is the ratio of the component with respect to Ai: T1ρi.
[0046]
Here, the analysis was performed using a two-component system (T1ρ1: amorphous component, T1ρ2: crystalline component), and the value was obtained by least square fitting using the following equation.
I (t) = fa1 ・ exp (-t / T1ρ1) + fa2 ・ exp (-t / T1ρ2)
fa1: Ratio of components to T1ρ1
fa2: Ratio of components to T1ρ2
fa1 + fa2 = 1
Here, T1ρ2 is used as T1ρ.
[0047]
(5) Birefringence of polyester film The retardation in the cross-sectional direction of the film after removing the metal plate of the laminated metal plate using a polarizing microscope was measured to determine the birefringence in the cross-sectional direction of the film.
[0048]
(6) Content takeout property Using a drawing machine, a laminated metal plate was cup-formed in a drawing process with a blank diameter of 100 mm and a drawing ratio (diameter before molding / diameter after molding): 1.88. Subsequently, the contents in which the egg, meat, and oatmeal were uniformly mixed were filled in the cup, and the lid was wrapped up, followed by retorting (130 ° C. × 90 minutes). After that, remove the lid, turn the cup upside down, shake it by hand a few times, take out the contents, and observe the extent of the contents remaining inside the cup to evaluate the ease of taking out the contents did.
(About the score)
A: The contents can be easily taken out, and there is no deposit on the inner surface of the cup after taking out.
○: It is difficult to take out the contents only by shaking by hand, but it can be easily taken out with a spoon or the like, and there is almost no deposit on the inner surface of the cup after removal.
X: It is difficult to take out the contents only by shaking by hand, and the contents cannot be taken out unless scraped with a spoon or the like, and a lot of deposits are observed on the inner surface of the cup after taking out.
[0049]
(7) Formability After applying wax to the laminated metal plate, a disk having a diameter of 179 mm was punched out to obtain a shallow drawn can with a drawing ratio of 1.60. Next, the drawing cup was redrawn with a drawing ratio of 2.10 and 2.80. Then, after performing doming forming according to a conventional method, trimming was performed, and then neck-in-flange processing was performed to form a deep drawn can. Focusing on the neck-in portion of the deep-drawn can thus obtained, the degree of film damage was visually observed.
(About the score)
(Double-circle): After a shaping | molding, a film is not damaged and film peeling is not recognized.
○: Molding is possible, but film peeling is observed.
X: The can is broken and cannot be molded.
[0050]
(8) Adhesion A peel test sample (width 15 mm × length 120 mm) was cut out from the can body portion of the can that could be molded in (7) above. Part of the film is peeled off from the long side end of the cut sample, and the part of the film peeled off by the tensile tester is opened in the opposite direction (angle: 180 °) from the chrome-plated steel sheet from which the film has been peeled. A peel test was performed at a speed of 30 mm / min to evaluate the adhesion. In addition, the contact | adhesion power measurement object surface was made into the can inner surface side.
(About the score)
A: 0.15 kg / 15 mm or more.
[0051]
○: 0.10 kg / 15 mm or more and less than 0.15 kg / 15 mm.
X: Less than 0.10 kg / 15 mm.
[0052]
(9) Impact resistance The can that was moldable in (7) above was filled with water, and 10 pieces were dropped from a height of 1.25 m onto the PVC tile floor for each test, A voltage of 6 V was applied to the metal can, the current value after 3 seconds was read, and the average value after 10 cans was measured.
(About the score)
A: Less than 0.01 mA.
A: 0.01 mA or more and less than 0.1 mA.
X: 0.1 mA or more.
[0053]
(10) Taste characteristics The can that was moldable in (7) above was subjected to a retort treatment at 120 ° C. for 30 minutes, filled with 350 ml of a fragrance aqueous solution d-limonene 25 ppm aqueous solution, and left for 45 days after sealing at 40 ° C. After that, it was opened and the change in odor was evaluated by the following criteria by sensory test.
○: Almost no change in odor is observed.
Δ: Some change in odor is observed.
X: A great change in odor is observed.
The evaluation results are shown in Table 2.
[0054]
[Table 1]

[0055]
[Table 2]

[0056]
As shown in Table 1 and Table 2, all of the inventive examples within the scope of the present invention exhibited good characteristics such as contents take-out property, moldability, adhesion, impact resistance and taste characteristics.
[0057]
In the examples of the present invention, those containing carnauba wax or stearic acid ester as the wax component have better contents removability. When the thickness of the region where the birefringence value of the film is 0.02 or less is less than 5 μm from the contact interface with the metal plate, the moldability is more excellent. If the relaxation time T1ρ is 270 msec or more, the moldability is more excellent. When 95% by mass or more of the polyester units constituting the film are ethylene terephthalate units, impact resistance and taste characteristics are more excellent.
[0058]
On the other hand, the comparative example outside the scope of the present invention was defective in at least one of the contents take-out property, taste characteristics, and moldability.
[0059]
【The invention's effect】
The laminated metal plate according to the present invention has good contents take-out properties, formability, adhesion, impact resistance, and taste characteristics, and is suitable as a container material for drawing or the like, particularly as a food container material.
[Brief description of the drawings]
FIG. 1 is a view showing a main part of a laminating apparatus for a metal plate.
[Explanation of symbols]
1 Metal plate (chrome plated steel plate)
2 Metal band heating device 3 Laminate roll 4a, 4b Film

Claims (6)

  A biaxially stretched polyester film having a melting point of 240 to 300 ° C., a carboxyl end group of 10 to 50 equivalents / ton, and substantially not containing an isophthalic acid component as an acid component is Resin Film A, and the biaxially stretched polyester resin film. Further, when a resin film containing a wax component of 0.10 to 2.0% by weight with respect to the resin is used as the resin film B, the resin film B is formed on the surface of the metal plate that becomes the inner surface of the container after the container is formed. A film-laminated metal plate for containers, wherein a resin film A is laminated on the surface of a metal plate that becomes the outer surface side of the container.   The film-laminated metal sheet for containers according to claim 1, wherein the wax component contains carnauba wax or stearic acid ester.   The region where the birefringence of the resin film A and the resin film B after lamination is 0.02 or less is less than 5 μm in the film thickness direction from the contact interface with the metal plate. Film laminated metal plate for containers.   The film laminate for containers according to any one of claims 1 to 3, wherein 95% by mass or more of the polyester units constituting the resin film A and the resin film B are ethylene terephthalate units and / or ethylene naphthalate units. Metal plate.   The film-laminated metal plate for containers according to any one of claims 1 to 4, wherein the resin film A and the resin film B have a thickness direction refractive index of 1.500 or more. The resin film B is composed of at least two layers, and the resin film B contains a wax component of 0.10 to 2.0% by weight with respect to the resin only in the uppermost layer in contact with the contents. The film-laminated metal plate for containers according to any one of claims 1 to 5 .

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