JP2006205575A - Polyester resin-laminated metal sheet for container - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyester resin-laminated metal sheet which is excellent in the pouring-off of contents, excellent in adhesion with a metal sheet, heat resistance and formability, and suitable as a material for lids and bodies of metal cans which are manufactured by forming processings such as draw forming and forming by ironing. <P>SOLUTION: The resin laminated metal sheet for container comprises a biaxially oriented polyester resin covering both surfaces of a metal sheet, wherein the resin layer that is to become the container inside after the shaping into a container consists of resin layer(s) of a single layer or plural layers mainly composed of a polyester, in which the resin layer contains 0.1-2.0% by mass of a wax component (in the case of plural layers, each layer containing 0.1-2.0% by mass of a wax component), and in which the resin layer surface after the shaping into the container and the retort treatment has an intensity ratio by the Laser-Raman method, I<SB>2968</SB>/I<SB>3085</SB>, in the range of 0.2≤I<SB>2968</SB>/I<SB>3085</SB>≤1.0 (wherein I<SB>2968</SB>indicates a Raman band intensity near 2,968 cm<SP>-1</SP>and I<SB>3085</SB>that near 3,085 cm<SP>-1</SP>). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a polyester resin laminated metal plate for containers. More specifically, the moldability and adhesion in the can making process are good, the impact resistance after filling the contents and the contents taking out after the retort treatment are excellent, and it is manufactured by molding processes such as drawing and ironing. The present invention relates to a polyester resin laminated metal plate suitable for a material of a lid or body of a metal can.

  Conventionally, the inner and outer surfaces of tin cans made of tin-free steel (TFS), aluminum, and the like have been subjected to various surface treatments such as a metal plate heated with a thermoplastic resin film or plating for the purpose of corrosion protection of the metal plate. Many methods of laminating on metal plates have been proposed.

  For example, Patent Document 1 discloses a polyester film for laminating metal plates made of a biaxially oriented polyester film having a specific density and a plane orientation coefficient. Patent Document 2 discloses a copolyester film for metal plate lamination, which is composed of a predetermined acid component and a glycol component and has a specific crystallinity.

  However, when the laminated metal plate proposed in these 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. .

Moreover, although patent document 3 prescribes | regulates the film surface after lamination by the contact angle with water from the point of the content taking-out property, in the food canned use, since the retort process at about 120 degreeC is performed as a sterilization process. This treatment changes the crystal structure of the polyester film and affects the takeout of the contents, so that a sufficient effect is not always obtained. In food canning applications, there are a wide variety of contents, so we handle a wide range from hydrophilic to oleophilic contents, and it is necessary to ensure the removability of various contents. Satisfactory performance is not always obtained simply by defining the corners.
JP-A 64-22530 JP-A-2-57339 JP 2004-168365 A

  Therefore, the present invention is to solve the above-described problems of the prior art, and is used in food canning applications, and is excellent in the ability to take out the contents even after retorting, and further has good adhesion to metal plates, heat resistance, and molding. An object of the present invention is to provide a polyester resin laminated metal plate that is excellent in workability and suitable for a material of a lid or body of a metal can manufactured by a forming process such as drawing or ironing.

As a result of intensive studies to solve the above problems, the inventors of the present invention have found that the laminated metal plate has a Raman band intensity (I ₃₀₈₅ ) near ₃₀₈₅ cm ⁻¹ by a laser Raman method on the surface of the film after container forming and retorting. A biaxially stretched polyester film whose film crystal structure is highly controlled so that the intensity ratio of Raman band intensity (I ₂₉₆₈ ) near ₂₉₆₈ cm ⁻¹ , I ₂₉₆₈ / I ₃₀₈₅ is in the range of 0.2 to 1.0. It has been found that the contents can be easily taken out. The gist of the present invention for solving the above problems is as follows.

The first invention is a resin-laminated metal plate for a container in which a biaxially stretched polyester resin is coated on both surfaces of a metal plate, and the resin layer on the side that becomes the inner surface of the container after the container is formed is a single-component polyester. It consists of a resin layer of layers or multiple layers, and contains 0.1 to 2.0% of a wax component in the resin layer by mass ratio (in the case of multiple layers, 0.1 to 2.0% by mass ratio in each layer) Of the Raman band intensity (I ₃₀₈₅ ) near ₃₀₈₅ cm ^{−1 and} the Raman band intensity (I ₂₉₆₈ ) near ₂₉₆₈ cm ⁻¹ by the laser Raman method on the resin layer surface after retorting. A polyester resin-laminated metal plate for containers, wherein the strength ratio, I ₂₉₆₈ / I ₃₀₈₅ is in the range of the formula (1).

0.2 ≦ I ₂₉₆₈ / I ₃₀₈₅ ≦ 1.0 Formula (1)
According to a second invention, in the first invention, a Raman band intensity (I ₃₀₈₅ ) near ₃₀₈₅ cm ⁻¹ and a Raman band intensity (I I) near 2968 cm ⁻¹ are measured by a laser Raman method on the surface of the resin layer after retorting. ₂₉₆₈ ), I ₂₉₆₈ / I ₃₀₈₅ is the strength ratio in the longitudinal direction (MD) of the laminated metal plate, I ₂₉₆₈ / I ₃₀₈₅ is in the range of formula (2), and the width direction of the laminated metal plate (TD The polyester resin-laminated metal plate for containers according to claim 1, wherein the strength ratio of I ₂₉₆₈ / I ₃₀₈₅ is in the range of the formula (3).

0.4 ≦ I ₂₉₆₈ / I ₃₀₈₅ ≦ 0.6 Formula (2)
0.3 ≦ I ₂₉₆₈ / I ₃₀₈₅ ≦ 0.5 Formula (3)
A third invention is the container according to the first or second invention, wherein in the polyester resin of the resin layer on the side that becomes the inner surface of the container after molding, 80 mol% or more of the structural units of the polyester are ethylene terephthalate units. Polyester resin laminated metal plate.

  According to a fourth aspect of the present invention, in the first to third aspects of the present invention, the resin layer mainly composed of polyester on the side that becomes the inner surface of the container after the container molding is composed of two or more layers, and the wax component is the uppermost layer in contact with the contents It is a polyester resin laminated metal plate for containers characterized by containing only 0.1 to 2.0% by mass ratio only in the layer constituting the.

  According to a fifth invention, in the first invention to the fourth invention, the resin layer formed on the side that becomes the outer surface of the container after the container molding is a resin layer mainly composed of polyester, wherein 80 mol% or more of the polyester unit is ethylene terephthalate and A polyester resin-laminated metal plate for containers, which is a unit of butylene terephthalate and has a glass transition point of 20 to 73 ° C. of the polyester resin.

  A sixth invention is the first invention to the fifth invention, wherein the region where the birefringence of the resin layer on the side that becomes the inner surface of the container after molding is 0.02 or less is in the film thickness direction from the contact interface with the metal plate A film-laminated metal plate for containers, wherein the thickness is less than 5 μm.

  The laminated metal plate according to the present invention is excellent as a content for taking out contents after retort processing, is excellent in adhesion and impact resistance, and is suitable as a material for containers for drawing, particularly food container containers.

  Even with a polyester resin having the same composition, the contents can be taken out differently depending on the production conditions of the laminated metal plate, the presence or absence of retorting, and the like. This was considered because the surface state of the resin layer was different. Until now, examination of the content taking-out property which paid its attention to the surface state of a resin layer is not made | formed. Therefore, the relationship between the surface state of the container inner surface side resin layer and the contents take-out property was investigated.

  Canned foods contain fats as contents. The polyester resin mainly has a structure of a dicarboxylic acid component such as terephthalic acid and a divalent diol component such as ethylene glycol. Aliphatic glycol components such as ethylene glycol are compatible with fatty chains such as paraffins and olefins in fats, while aromatic dicarboxylic acid components such as terephthalic acid are fatty acids such as paraffins and olefins in fats. It is thought that the affinity with the chain is inferior. The inventors of the present invention have thought that the arrangement of glycol components and aromatic dicarboxylic acids is different on the surface of the resin layer of the laminated metal plate, and as a result, the content takeout property changes.

Laser Raman spectroscopy is a method for investigating the surface state of a resin layer. The Raman band intensity (I ₂₉₈₆ ) near ₂₉₈₆ cm ⁻¹ by laser Raman spectroscopy reflects the arrangement of C—H bonds of the diol component on the resin layer surface. When this intensity is relatively large, the polyester resin chain on the film surface The arrangement is in a relatively disordered state, and in the case of a biaxially stretched film, the film surface is considered to be in a state in which many amorphous portions exist. The Raman band intensity (I ₃₀₈₅ ) near ₃₀₈₅ cm ⁻¹ by laser Raman spectroscopy reflects the arrangement of C—H bonds of benzene rings on the surface of the resin layer. If this intensity is relatively large, the arrangement is aroma such as benzene rings. In the case of a biaxially stretched film, the group ring plane is parallel to the film surface direction, and it is considered that there are many crystal parts and the crystals are oriented parallel to the film surface.

From the above, it is considered that the strength ratio between the two (I ₂₉₈₆ / I ₃₀₈₅ ) may be an index indicating the affinity between the resin layer surface and the fats. As a result of further investigation on this point, the strength ratio between the two (I ₂₉₆₈ / I ₃₀₈₅ ) and the content take-out properties are clear, and if the strength ratio between the two after retort treatment is specified within an appropriate range, it is excellent in canned foods that have undergone retort treatment. It has been found that the material removal property can be expressed. The present invention is based on this finding.

Hereinafter, the present invention will be described in detail. In the present invention, it is a metal plate coated on both sides with a polyester resin, and in particular, the film on the side that becomes the inner surface of the container after forming the container has a Raman band strength of around 3085 cm ⁻¹ by laser Raman spectroscopy in order to obtain excellent content takeout properties. The intensity ratio of the Raman band in the vicinity of 2968 cm ⁻¹ has a value after retorting of 0.2 to 1.0.

Here, 3085Cm intensity ratio of the Raman band intensity of a Raman band intensity and 2968cm around ^-1 around ^-1 becomes higher crystalline orientation of the film surface is less than 0.2, a film breakage, film cracking etc. during can manufacturing occurs Therefore, workability is reduced, and film cracking due to retort treatment occurs. On the other hand, if it exceeds 1.0, the crystal orientation on the film surface becomes small and the amorphous part increases. Therefore, the surface roughness of the film surface is increased, and the water resistance and oil resistance are decreased. As a result, the physical and chemical affinity with the content is increased, and the content takeout property is deteriorated. . By setting the strength ratio in the range of 0.2 to 1.0, the processability is excellent and the contents can be easily taken out.

  Further, the Raman band intensity ratio of the Raman band intensity in the longitudinal direction (MD) of the laminated metal plate is in the range of 0.4 to 0.6, and the intensity of the Raman band intensity in the width direction (TD) of the laminated metal plate. When the ratio is in the range of 0.3 to 0.5, the processability is excellent, the affinity with the content is effectively reduced, and the content takeout property is more excellent.

The intensity ratio between the Raman band intensity near 3085 cm ⁻¹ and the Raman band intensity near 2968 cm ⁻¹ by laser Raman spectroscopy can be controlled by controlling the amount of catalyst added to the resin raw material, intrinsic viscosity, the amount of crystallization nucleating agent added, stretching conditions, etc. Also, it can be controlled by the laminating conditions. For example, the strength ratio can be lowered by increasing the catalyst amount of the resin raw material, lowering the intrinsic viscosity, increasing the addition amount of the crystallization nucleating agent, or stretching conditions (such as increasing the stretching ratio). In addition, depending on the laminating conditions (lowering the metal plate temperature at the start of laminating, lowering the laminating roll temperature, lowering the laminating roll nip pressure, shortening the laminating roll nip time, shortening the time until cooling after laminating, etc.) The Raman band intensity ratio can be reduced. In addition, the Raman band intensity ratio by laser Raman spectroscopy can be obtained by the method described in Examples described later.

  Moreover, it is preferable that the biaxially stretched polyester film on the inner surface side of the can has an ethylene terephthalate unit as a main constituent component from the viewpoint of the required performance of content takeout properties, heat resistance and taste characteristics. Specifically, it is preferable that 80 mol% or more of the polyester units constituting the film are ethylene terephthalate units, and thereby, particularly high content takeout properties, heat resistance and taste characteristics can be obtained. When the ethylene terephthalate unit is less than 80 mol%, the crystallinity of the film is remarkably lowered, and the characteristics are deteriorated.

  On the other hand, the biaxially stretched polyester film may be obtained by copolymerizing other dicarboxylic acid components and glycol components within a range that does not impair heat resistance and taste characteristics. Examples of the dicarboxylic acid component include isophthalic acid, Aromatic dicarboxylic acids such as naphthalenedicarboxylic acid, diphenyldicarboxylic acid, diphenylsulfonedicarboxylic acid, diphenoxyethanedicarboxylic acid, 5-sodiumsulfoisophthalic acid, phthalic acid; oxalic acid, succinic acid, adipic acid, sebacic acid, dimer acid, Mention may be made of aliphatic dicarboxylic acids such as maleic acid and fumaric acid; alicyclic carboxylic acids such as cyclohexanedicarboxylic acid; oxycarboxylic acids such as p-oxybenzoic acid, and the like. One or more of these may be used. be able to.

  Examples of the glycol component include aliphatic glycols such as propanediol, butanediol, pentanediol, hexanediol, and neopentyl glycol; alicyclic glycols such as cyclohexanedimethanol; aromatic glycols such as bisphenol A and bisphenol S. , Diethylene glycol and the like, and one or more of these can be used.

  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.

  In the present invention, two or more of the above polymers can be blended and used. If necessary, an antioxidant, a heat stabilizer, an ultraviolet absorber, a plasticizer, a pigment, an antistatic agent, a crystal nucleating agent, and the like can be blended.

  The film used in the present invention preferably has a polyester intrinsic viscosity of 0.50 dl / g or more, more preferably 0.60 dl / g or more, particularly preferably 0.63 dl from the viewpoint of improving mechanical properties, laminating properties and taste properties. / G or more. An intrinsic viscosity of less than 0.50 dl / g is not preferred because taste characteristics deteriorate due to oligomer elution.

  Moreover, in this invention, it prescribes | regulates that the resin film which becomes a container inner surface side after container shaping | molding is a polyester film containing 0.1-2.0% of wax components with respect to resin by mass ratio. By adding a wax component, (i) reducing the surface free energy of the film and (ii) imparting lubricity to the film surface. The effect of (i) makes it difficult for the content to adhere to the film, and the effect of (ii) makes it possible to dramatically improve the take-out property of the content by reducing the friction coefficient of the film surface.

  The reason for limiting to 0.1% or more is that when the content is less than 0.1%, the effects (i) and (ii) described above become poor and the contents can be easily taken out. In addition, the reason for limiting to 2.0% or less is that if it exceeds 2.0%, the contents take-out property is almost saturated, and the effect due to the increase in the amount of addition is not seen, and the productivity is reduced in film formation. However, this is disadvantageous in terms of cost.

  As the wax component to be added, organic / inorganic lubricants can be used, but organic lubricants such as polyolefin resins are desirable, and in particular, polyethylene and polypropylene obtained by polymerizing one or more α-olefins. , Polybutene, polypentene, ethylene-propylene copolymer, ethylene-butene copolymer, and the like. These olefin resins may be used alone or in combination of two or more. The polyolefin resin may be copolymerized with acrylic acid, methyl acrylate, methacrylic acid, methyl methacrylate, maleic anhydride, or the like, as long as the olefin component is a main component.

  In addition, the polyester film to which the olefin resin used in the present invention is added is prepared by mixing a predetermined amount of the olefin resin directly or in advance with a blender, a mixer, etc., and then melt-kneading using a normal single-screw or twin-screw extruder. In addition, it can be manufactured by a normal film forming method. In addition, 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, 0.1 to 2.0% of a wax component may be added to each layer, but it is necessary that the wax component is added to the uppermost layer of the film in contact with the contents From the viewpoint of economy and the like, it is desirable that 0.1 to 2.0% of the wax component is added only to the uppermost layer of the film with respect to the film constituting the uppermost layer.

  Moreover, as for the resin film which becomes a container inner surface side after container shaping | molding, it is desirable that the area | region whose birefringence is 0.02 or less shall be less than 5 micrometers in a film thickness direction from a contact interface with a metal plate. In the production of a laminated metal plate, the film is usually brought into contact with a heated metal plate and subjected to pressure bonding to melt the film resin at the interface of the metal plate and to wet the metal plate so as to adhere to the film. 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. . 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. . The birefringence can be measured by a known method.

  The biaxially stretched polyester film that becomes the outer surface of the container after the container molding used in the present invention is mainly composed of polyester in which 80 mol% or more of the polyester units are ethylene terephthalate and / or butylene terephthalate units from the viewpoint of impact resistance. A resin film is preferred.

  On the other hand, the biaxially stretched polyester film on the outer surface side of the container may be copolymerized with other dicarboxylic acid components and glycol components within a range not impairing impact resistance. Examples of the dicarboxylic acid component include: Aromatic dicarboxylic acids such as isophthalic acid, naphthalenedicarboxylic acid, diphenyldicarboxylic acid, diphenylsulfonedicarboxylic acid, diphenoxyethanedicarboxylic acid, 5-sodiumsulfoisophthalic acid, phthalic acid; oxalic acid, succinic acid, adipic acid, sebacic acid, Examples thereof include aliphatic dicarboxylic acids such as dimer acid, maleic acid, and fumaric acid; alicyclic carboxylic acids such as cyclohexanedicarboxylic acid; oxycarboxylic acids such as p-oxybenzoic acid, and the like. The above can be used.

  Examples of the glycol component include aliphatic glycols such as propanediol, butanediol, pentanediol, hexanediol, and neopentyl glycol; alicyclic glycols such as cyclohexanedimethanol; aromatic glycols such as bisphenol A and bisphenol S. , Diethylene glycol and the like, and one or more of these can be used.

  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.

  In the present invention, two or more of the above polymers can be blended and used. If necessary, an antioxidant, a heat stabilizer, an ultraviolet absorber, a plasticizer, a pigment, an antistatic agent, a crystal nucleating agent, and the like can be blended.

  Moreover, it is necessary from a viewpoint of improving impact resistance that the glass transition point of the resin film which becomes the said container outer surface side is 20-73 degreeC. If the glass transition point is less than 20 ° C., the impact resistance is good, but the heat resistance when subjected to a heat treatment such as retort treatment is not preferred. On the other hand, when the glass transition point exceeds 73 ° C., the impact resistance deteriorates.

  The thickness of the film is preferably 3 to 50 μm on both the inner surface side and the outer surface side, more preferably 8 in terms of formability after being laminated to the metal, coatability to the metal, impact resistance, and taste characteristics. ˜30 μm.

  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 laminate roll) and thermally fused.

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 10 ° C. or more from the film melting point, and the nip time (nip length / lamination speed) is preferably in the range of 5 msec to 50 msec. Furthermore, as the temperature history received by the film during lamination, it is preferable that the time of contact at a temperature equal to or higher than the melting point of the film is 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 size of the apparatus, which is uneconomical.

  As the metal plate, an aluminum plate or a steel plate that is widely used as a material for cans can be used, and in particular, a surface-treated steel plate (two-layered film in which the lower layer is made of chromium metal 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.

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 chromium-plated steel sheet (TFS). 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 and chromium hydroxide adhesion amount to 120 mg / m ² and 15 mg / m ² in terms of Cr, respectively.

  Next, using a metal strip laminating device, the chrome-plated steel plate obtained above is heated with a metal strip heating device, and a resin film is laminated (heat-sealed) on both sides of the chrome-plated steel strip with a laminating roll, A plate (laminated steel plate) was produced. The laminating roll was an internal water cooling type, and cooling water was forcibly circulated during laminating to perform cooling during film adhesion. Adjustment of the Raman band intensity ratio by laser Raman was performed by changing the laminating conditions to the metal band. The contents of the laminated resin film and the lamination conditions are shown in Table 1.

  The properties of the used biaxially stretched polyester film are the following methods (1) to (3), and the properties of the laminated metal plate produced by the above method are the following methods (4) to (6). Was measured and evaluated. The results are listed in Tables 1 and 2.

(1) Raman band intensity ratio (R)
Cut laminated metal plate from the bottom of the retort cans inner surface of the laminated metal sheet longitudinally (MD), with the width direction (TD), the Raman bands around the Raman bands and 2968cm ^-1 in the vicinity of 3085cm ^-1 by laser Raman Each Raman spectrum was measured, and the Raman band intensity ratio (R) was determined by the following formula.
R = I ₂₉₆₈ / I ₃₀₈₅
I ₂₉₆₈ : Raman band intensity near ₂₉₆₈ cm ⁻¹ I ₃₀₈₅ : Raman band intensity near ₃₀₈₅ cm ⁻¹ <Measurement conditions>
Excitation light source: Ar laser (λ = 514.5 nm), output 2 mW
Microscopic magnification: x100
Longitudinal direction (MD): Laser light is incident so that the laser polarization plane is parallel to the longitudinal direction of the laminated metal plate.
Width direction (TD): Laser light is incident so that the laser polarization plane is perpendicular to the longitudinal direction of the laminated metal plate.

(2) Glass transition point of polyester After the polyester film was completely melted at 290 ° C., a sample rapidly quenched with liquid nitrogen was measured with a differential scanning calorimeter (DSC Q100 manufactured by TA Instruments Inc.). The measurement was carried out at a temperature elevation rate of ° C / min.

(3) Birefringence index 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, and the birefringence index in the cross-sectional direction of the film was determined.

(4) Content take-out property Using a drawing machine, a laminated metal plate was cup-formed at a drawing step with a blank diameter: 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 into the cup, and the lid was wrapped up, followed by retorting (125 ° 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.

(5) Adhesiveness After applying wax on 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 drawn cup was redrawn with a drawing ratio of 2.20 and 2.90. 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. A sample for peel test (width 15 mm × length 120 mm) was cut out from the can body. 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 per 15 mm width. In addition, the contact | adhesion power measurement object surface was made into the can inner surface side.
(About the score)
A: 1.47 N / 15 mm or more (0.15 kgf / 15 mm or more).
A: 0.98 N / 15 mm or more and less than 1.47 N / 15 mm (0.10 kgf / 15 mm or more, less than 0.15 kgf / 15 mm).
X: Less than 0.98 N / 15 mm (less than 0.10 kgf / 15 mm).

(6) Impact resistance The cans that could be molded in (5) above were 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.

  As shown in Tables 1 and 2, all the inventive examples within the scope of the present invention were excellent in quality stability and exhibited good characteristics. On the other hand, the comparative example which deviates from the scope of the present invention has poor contents take-out property, adhesion and impact resistance.

Claims (6)

A resin-laminated metal plate for containers in which biaxially stretched polyester resin is coated on both surfaces of a metal plate, and the resin layer on the side that becomes the inner surface of the container after container molding is a single-layer or multi-layer mainly composed of polyester It consists of a resin layer and contains 0.1 to 2.0% wax component in the resin layer by mass ratio (in the case of multiple layers, each layer contains 0.1 to 2.0% wax component by mass ratio) ), The intensity ratio of the Raman band intensity (I ₃₀₈₅ ) near ₃₀₈₅ cm ^{−1 and} the Raman band intensity (I ₂₉₆₈ ) near ₂₉₆₈ cm ⁻¹ by the laser Raman method of the resin layer surface after retorting, I ₂₉₆₈ / I ₃₀₈₅ is in the range of formula (1), a polyester resin laminated metal plate for containers.
0.2 ≦ I ₂₉₆₈ / I ₃₀₈₅ ≦ 1.0 Formula (1) Molded into a container, the intensity ratio of the Raman band intensity near 2968cm ^-1 Raman band intensity (I ₃₀₈₅₎ of around 3085cm ^-1 by laser Raman method of the resin layer surface after retort treatment _{(I 2968), I 2968 /} I ₃₀₈₅ is the strength ratio in the longitudinal direction (MD) of the laminated metal plate, I ₂₉₆₈ / I ₃₀₈₅ is in the range of formula (2), and the strength ratio in the width direction (TD) of the laminated metal plate is I ₂₉₆₈ / I ₃₀₈₅ The polyester resin-laminated metal plate for containers according to claim 1, wherein is in the range of the formula (3).
0.4 ≦ I ₂₉₆₈ / I ₃₀₈₅ ≦ 0.6 Formula (2)
0.3 ≦ I ₂₉₆₈ / I ₃₀₈₅ ≦ 0.5 Formula (3)   3. The polyester resin for containers according to claim 1, wherein the polyester resin of the resin layer on the side that becomes the inner surface of the container after forming the container comprises 80 mol% or more of the structural units of the polyester being ethylene terephthalate units. Laminated metal plate.   The resin layer mainly composed of polyester on the side that becomes the inner surface of the container after the molding of the container is composed of two or more layers, and the wax component is 0.1% by mass ratio only in the layer constituting the uppermost layer in contact with the contents. The polyester resin laminate metal plate for containers according to any one of claims 1 to 3, wherein the content is 2.0%.   The resin layer formed on the side that becomes the outer surface of the container after the molding of the container is a resin layer mainly composed of polyester, and 80 mol% or more of the polyester units are ethylene terephthalate and / or butylene terephthalate units, and the glass transition point of the polyester resin The polyester resin-laminated metal plate for containers according to any one of claims 1 to 4, wherein the temperature is 20 to 73 ° C.   The region where the birefringence of the resin layer on the side that becomes the inner surface of the container after molding is 0.02 or less is less than 5 µm in the film thickness direction from the contact interface with the metal plate. Item 6. The container-laminated metal sheet according to any one of Items 5 to 5.