JP3812589B2 - Film laminated metal plate for containers - Google Patents

Description

The present invention is mainly related to the film-laminated metal plate used in food cans can body and lid. More particularly, good moldability and adhesion in can manufacturing process, but about the container film laminated metal sheet excellent in the content was taken out and impact resistance after content filling.

  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.

  Many of these proposals relate to improvements in adhesion and formability between the film and the metal plate as the base material, and the technical idea is generally (1) for films having polar groups (polyester resins, etc.). The present invention relates to application (for example, Patent Document 1), (2) increase in surface free energy represented by activation by treatment such as corona discharge on the film surface (for example, Patent Document 2).

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.
JP-A 63-236640 Japanese Patent Laid-Open No. 5-200961

Therefore, the present invention takes into account the above circumstances, and ensures film take-out properties (ease of take-out of contents), and has a film laminate for containers that has moldability, adhesion, and impact resistance required for container processing. An object is to provide a metal plate .

  As a result of intensive studies to solve the above problems, the present inventors have found that this object can be achieved by a laminated metal plate using a film containing polyester as a main component and an appropriate amount of a wax component added thereto. The invention has been reached.

That is, the gist of the present invention is as follows.
(1) a thermoplastic resin film containing as a main component a polyester a thermoplastic resin film to the resin film A, the port Riesuteru mainly, of from 0.10 to 2.0% relative to the resin mass ratio When the resin film containing the wax component is the resin film B, the resin film B is laminated on the surface of the metal plate that becomes the inner surface of the container after molding the container, and the resin film is formed on the surface of the metal plate that becomes the outer surface of the container after molding the container. A film-laminated metal plate for containers, wherein A is laminated.

(2) The film-laminated metal plate for containers according to (1), wherein the resin film B contains carnauba wax or stearic acid ester as a wax component.
(3) The resin film A and / or the resin film B is a biaxially stretched polyester film in which the relaxation time T1ρ of 1,4-coordinated benzene ring carbon in the structural analysis by solid high-resolution NMR is 150 msec or more. The film-laminated metal plate for containers according to (1) or (2).

(4) The container film according to any one of (1) to (3) , wherein 90 mol% or more of the polyester units constituting the resin film A and / or the resin film B are ethylene terephthalate units. Laminated metal plate.

(5) The resin film A and / or the resin film B is composed of at least two layers, and the intrinsic viscosity difference between the laminate layer in contact with the metal plate and each of the other layers excluding this layer is 0.01-0. 5. The film-laminated metal plate for containers according to any one of the above (1) to (4) , which is 5.
(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:

(7) A can body and / or lid for a can container obtained by processing the film-laminated metal plate for containers according to any one of (1) to (6), wherein the inner surface of the container is a resin. A member for a can container, wherein the laminate surface of the film B and the outer surface side of the container are the laminate surface of the resin film A.
(8) A can container obtained by processing the film-laminated metal plate for a container according to any one of (1) to (6), wherein the container inner surface is a laminate surface of the resin film B, and the container outer surface A can container characterized in that the side is a laminated surface of a resin film A.

  The laminated metal plate according to the present invention has good contents take-out properties, formability, adhesion, and impact resistance, and is suitable as a container material for drawing or the like, particularly as a food container material. Moreover, it can also be used as a container material for performing more advanced processing such as a DTR can.

Hereinafter, the present invention will be described in detail.
The laminated metal plate of the present invention uses a resin film mainly composed of polyester as a resin film (resin film A, resin film B). The polyester as the main component of the resin film is a polymer composed of a dicarboxylic acid component and a glycol component. Examples of the dicarboxylic acid component include terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, diphenyldicarboxylic acid, and 5-sodium sulfoisophthalic acid. , Aromatic dicarboxylic acids such as phthalic acid, oxalic acid, succinic acid, adipic acid, sebacic acid, dimer acid, maleic acid, fumaric acid and other aliphatic dicarboxylic acids, cyclohexanedicarboxylic acid and other aliphatic dicarboxylic acids, p-oxy Examples thereof include oxycarboxylic acids such as benzoic acid. Of these dicarboxylic acid components, terephthalic acid is preferred from the viewpoints of heat resistance and taste characteristics.

  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. Glycol and the like. Of these, ethylene glycol is preferable among these glycol components. These dicarboxylic acid components and glycol components may be used in combination of two or more.

  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, the metal element amount of the metal compound arbitrarily selected from the antimony compound, germanium compound, and titanium compound contained in the polyester used is the mass ratio in terms of heat resistance and taste characteristics, with respect to the polyester resin. It is preferably 0.01 ppm or more and less than 1000 ppm, more preferably 0.05 ppm or more and less than 800 ppm, and particularly preferably 0.1 ppm or more and less than 500 ppm.

  It is preferable that a germanium compound is mainly contained since taste characteristics after receiving a high-temperature heat history such as drying and retort treatment in the can manufacturing process are improved. Further, it is preferable to mainly contain an antimony compound because the amount of diethylene glycol by-produced can be reduced and the heat resistance becomes good. Further, as a heat stabilizer, a phosphorus compound may be added in an amount of 10 to 200 ppm, preferably 15 to 100 ppm, based on the polyester resin. Examples of the phosphorus compound include phosphoric acid and phosphorous acid compound, but are not particularly limited.

  Moreover, antioxidant, a heat stabilizer, a ultraviolet absorber, a plasticizer, a pigment, an antistatic agent, a crystal nucleating agent, etc. can be mix | blended with polyester as needed.

  Polyester composed of the above has excellent mechanical properties such as tensile strength, elastic modulus and impact strength, and has polarity. By using this as the main component, the film adhesion and moldability are improved to a level that can withstand container processing. It is also possible to impart impact resistance after processing the container.

Moreover, in this invention, the resin film (resin film B) which becomes a container inner surface side after container shaping | molding is a polyester film containing a 0.10-2.0% wax component with respect to resin by mass ratio. Stipulate. Reason for containing a wax component as the additive is in reducing the surface energy of the off Irumu, this thus Ri contents thereof are hardly adhered to the film, be dramatically improved extraction of the contents It becomes possible.

The reason why the content is limited to 0.10% or more is that when the content is less than 0.10%, the effect that the above-described content becomes difficult to adhere to the film becomes poor, and the take-out property of the content is poor. In addition, 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.

As the wax component to be added, an organic / inorganic lubricant can be used, but an organic lubricant such as a fatty acid ester is desirable, and among them, carnauba wax which is one of plant waxes and is a natural wax (main component: CH ₃ (CH ₂ ) ₂₄ COO (CH ₂ ) ₂₉ CH ₃ and also contains various aliphatic and alcohol components.) Or, stearic acid ester makes it difficult for the above contents to adhere to the film And is easy to add to the film because of its molecular structure. In addition, the polyester film containing the above-described wax can be manufactured by a normal film forming method after blending a predetermined amount of wax with polyester.

  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 contents are not absorbed and the above-described effects can be reliably expressed. It becomes possible.

  Furthermore, when the purpose is to apply to a more advanced processing container such as a DTR can, the polyester film has a relaxation time T1ρ of 1,4-coordinated benzene ring carbon in the structural analysis by solid high resolution NMR. It is preferable that it is a biaxially stretched polyester film which is 150 msec or more. This is because the biaxially stretched film has characteristics superior to those of the unstretched film, and properties such as tensile strength, tear strength, impact strength, water vapor permeability, and gas permeability are remarkably improved.

  The relaxation time T1ρ represents molecular mobility. When the relaxation time T1ρ is increased, the restraining force of the amorphous part in the film is increased. In the state of the biaxially stretched film, when the relaxation time T1ρ of the benzene ring carbons at positions 1 and 4 is increased, a stable structure similar to the crystal structure is formed by controlling the molecular alignment of the part. It becomes possible to suppress crystallization of the amorphous part in the film, that is, the mobility of the amorphous part is lowered, and the reorientation behavior for crystallization is suppressed. By setting the relaxation time T1ρ to 150 msec or more, the above-described excellent effects can be sufficiently exhibited, and excellent moldability and impact resistance can be obtained even when a high degree of processing is performed after lamination. It becomes like this. From the above viewpoint, the relaxation time T1ρ is preferably 180 msec or more, and more preferably 200 msec or more.

  The relaxation time T1ρ can be set to 150 msec or more by using a combination of a high temperature preheating method and a high temperature stretching method in the longitudinal stretching step during film production, but is not particularly limited. It is also possible by optimizing the viscosity, catalyst, diethylene glycol amount, stretching conditions, heat treatment conditions, and the like. The preheating temperature for longitudinal stretching during film production is preferably 90 ° C. or higher, more preferably 100 ° C. or higher, and still more preferably 110 ° C. or higher. The stretching temperature is preferably 105 ° C. or higher, more preferably 110 ° C. or higher, and still more preferably 115 ° C. or higher.

  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. . 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 thus it is possible to ensure excellent adhesion. Become.

  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).

Δn = R / d (1)
However, d: thickness of a film layer Next, the measuring method of retardation is demonstrated. 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: the wavelength of monochromatic light, the birefringence Δn is defined by the equation (3) derived from the 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.

  The suppressed molecular mobility expressed by the relaxation time T1ρ defined in the present invention is less effective when the film is completely melted, and crystallization easily occurs in the subsequent processing and heat treatment, and the film formability is reduced. It has the disadvantage of deteriorating. On the other hand, as described above, in order to ensure film adhesion, 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.

  Further, as the polyester, a polyester mainly composed of polyethylene terephthalate is preferable, and 90 mol% or more of the polyester units are preferably ethylene terephthalate units from the viewpoint of impact resistance. Moreover, if it is 95 mol% or more, the characteristics can be further improved, which is further desirable.

  The configuration of the resin film used in the present invention may be a single layer or a multilayer. However, in the case of a resin film composed of at least two layers, it is excellent that the intrinsic viscosity difference between the laminate layer in contact with the metal plate and each of the other layers excluding this layer is 0.01 to 0.5. It is also desirable from the viewpoint of developing moldability and impact resistance. Of course, 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. It is desirable that wax is added only to the film.

  Although it does not prescribe | regulate especially as thickness of the whole film, it is desirable that it is 5-60 micrometers, More preferably, it is 10-40 micrometers.

  Further, it is desirable that the film before lamination has a plane orientation coefficient of 0.15 or less in order to develop excellent moldability. When the plane orientation coefficient exceeds 0.15, the orientation of the entire film becomes high, and the formability after lamination deteriorates.

  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 (resin film).

  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.

  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).

  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 of the metal plate 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. If it is less than 1 msec, the film is not sufficient to adhere to the metal plate, and if it exceeds 20 msec, the effect of suppressing the molecular mobility in the vicinity of the adhesion surface with the metal plate is lost. This is because sufficient moldability may not be obtained.

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. Further, 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 the equipment strength is required, which is uneconomical.

  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 the 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.
Example 1
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. 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 this time, electrolysis conditions adjusted to metallic chromium adhering amount and chromium hydroxide deposition amount (current density, the quantity of electricity, etc.), and adjusted to ^{120mg / m 2, 15mg / m} 2 respectively.

  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. A laminated metal strip is manufactured by laminating (heat-sealing) a resin film (resin film B) 4a, which will be the inner surface of the container later, and a resin film (resin film A) 4b, which will be the outer surface of the container after molding, did. 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. Table 1 shows the contents of the laminated resin film and the lamination temperature conditions. 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.

  The properties of the used film are the following (1) and (2), and the properties of the laminated metal plate produced by the above method are measured and evaluated by the following methods (3) to (6). did. (1) and (2) are properties of the original film before lamination, but these properties are not changed after lamination.

(1) Relaxation time T1ρ
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. In order to improve the accuracy, 512 integrations were performed). The pulse repetition time was 5 to 15 seconds.

The T1ρ value can usually be described by the following equation, and can be obtained from the slope by semi-logarithm plotting the peak intensity observed for each holding time.
I (t) = Σ (Ai) exp (-t / T1ρi)
However, the ratio of the component with respect to Ai: T1ρi Here, the analysis was carried out by 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.

(2) Melting | fusing point of polyester The polyester was crystallized, and it measured with the temperature increase rate of 10 degree-C / min with the differential scanning calorimeter (DSC-2 type | mold by Perkin-Elmer).

(3) Content take-out property Using a drawing machine, a laminated metal plate was cup-formed in 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 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.

(4) 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. The degree of damage of the deep drawn can film thus obtained was visually observed.
(About the score)
(Double-circle): After a shaping | molding, a film is not damaged and whitening is not recognized.
○: Molding is possible, but film whitening is observed.
X: The can is broken and cannot be molded.

(5) Adhesion A peel test sample (width 15 mm × length 120 mm) was cut out from the can body portion of the can which could be molded in the above (4). A part of the film is peeled off from the long side end on the inner surface side of the cut out sample, and the part of the film peeled off by the tensile tester is in the direction opposite to the chrome-plated steel sheet from which the film is peeled (angle: 180 °) A peel test was conducted at a tensile 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 kgf / 15 mm or more O: 0.10 kgf / 15 mm or more, less than 0.15 kgf / 15 mm X: Less than 0.10 kgf / 15 mm

(6) Impact resistance After filling the cans that were moldable in (4) above with water and dropping 10 pieces of each test from a height of 1.25 m onto the PVC tile floor surface, 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 B: 0.01 mA or more, less than 0.1 mA X: 0.1 mA or more Evaluation results are shown in Table 1.

表１に示すように、本発明範囲内の発明例の鋼板は、いずれも内容物取り出し性、成形性、密着性、耐衝撃性に優れている。また、緩和時間Ｔ１ρが１５０ｍｓｅｃ以上の発明例の鋼板は、成形性、密着性、耐衝撃性がより優れている。

As shown in Table 1, all of the steel sheets of the invention examples within the scope of the present invention are excellent in contents take-out property, formability, adhesion, and impact resistance. Further, the steel sheet of the invention example having a relaxation time T1ρ of 150 msec or more is more excellent in formability, adhesion, and impact resistance.

  In addition, when laminating the resin film defined in the present invention on a metal plate, the steel sheet of the invention example in which the time at which the film temperature at the interface in contact with the metal plate is equal to or higher than the melting point of the film is 1 to 20 msec is an invention that deviates from the above temperature. Compared to the steel plate of the example, formability, adhesion, and impact resistance are more excellent.

  On the other hand, the steel sheets of Comparative Examples 1 to 3 in which the resin film deviates from the scope of the present invention are inferior in contents take-out property, and the steel sheets of Comparative Examples 4 and 5 are inferior in formability.

(Example 2)
As shown in Example 1, the film-laminated metal plate according to the present invention has excellent performance, and can be applied to almost all food can containers currently on the market. However, from the pursuit of cost performance in the future, it is expected that the degree of processing of canned food will become more severe, and it is essential that a laminated metal plate with higher formability is required. Therefore, in this example, the performance such as formability was evaluated under the condition that the working degree was further increased, and the effectiveness of the film laminate metal plate according to the present invention was investigated from the viewpoint of future technology.

  A chrome-plated steel sheet produced under the same conditions as in Example 1 is used, and a metal strip laminating apparatus shown in FIG. A resin film (resin film B) 4a and a resin film (resin film A) 4b which becomes the outer surface of the container after container molding were laminated (heat-sealed) on the other surface to produce a laminated metal strip. The resin film 4a which becomes the container inner surface side after the container molding uses a resin film 4b which becomes the container outer surface side to which a wax is added (both are biaxially stretched films within the scope of the present invention). Cooling was performed during film bonding. When laminating the resin film on the metal plate, the time during which the film temperature at the interface in contact with the metal plate was equal to or higher than the melting point of the film was set in the range of 1 to 20 msec. The contents of the laminated resin film are shown in Table 2.

  In addition, the characteristic of the film measured and evaluated the following (1)-(4) and the characteristic of the laminated metal plate manufactured by the above method by the method of following (5)-(8). The characteristics of (1) to (4) do not change before and after lamination.

(1) Relaxation time T1ρ
Evaluation was performed in the same manner as in Example 1 (1).
(2) Melting | fusing point of polyester It evaluated by the method similar to (2) of Example 1. FIG.

(3) Birefringence of polyester film By the method described in the embodiment, 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, and the double-refraction in the cross-sectional direction of the film is measured. The refractive index was determined.

(4) Intrinsic Viscosity Polyester used for each layer of the two-layer PET was dissolved in orthochlorophenol, the intrinsic viscosity was measured at 25 ° C., and the difference between the intrinsic viscosities was determined.
(5) Content takeout property Evaluation was performed in the same manner as in Example 1, (3).

(6) 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 1.80. Next, the drawn cup was redrawn with a drawing ratio of 2.20 and 2.90. The degree of film damage of the deeply drawn can thus obtained was visually observed and evaluated in the same manner as in Example 1 (4).

(7) Adhesiveness The can that was moldable in the above (6) was evaluated by the same method as (5) shown in Example 1. The scores are shown below.
(Score)
A: 0.25 kgf / 15 mm or more B: 0.10 kgf / 15 mm or more, less than 0.25 kgf / 15 mm X: less than 0.10 kgf / 15 mm

(8) Impact resistance The cans that could be molded in (6) above were filled with water, and for each test, 10 pieces were dropped from a height of 1.50 m onto the PVC tile floor, 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.
A: Less than 0.01 mA B: 0.01 mA or more to less than 0.1 mA X: 0.1 mA or more Evaluation results are shown in Table 3.

表２および表３に示すように、本発明範囲内の発明例は、加工度をアップした条件下でも、いずれも内容物取り出し性、成形性、密着性、耐衝撃性に優れている。

As shown in Tables 2 and 3, the inventive examples within the scope of the present invention are all excellent in content take-out property, moldability, adhesion, and impact resistance even under conditions where the degree of processing is increased.

  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. When 90 mol% or more of the polyester units constituting the film are ethylene terephthalate units, the impact resistance is more excellent.

The figure which shows the principal part of the laminating apparatus of a metal plate

Explanation of symbols

1 Metal plate (chrome plated steel plate)
2 Metal belt heating device 3 Laminate roll 4a, 4b Film

Claims (8)

  A thermoplastic resin film containing polyester as a main component is a resin film A, and a thermoplastic resin film containing polyester as a main component, which contains a wax component in a mass ratio of 0.10 to 2.0% with respect to the resin. When the resin film is a resin film B, the resin film B is laminated on the surface of the metal plate that becomes the inner surface of the container after forming the container, and the resin film A is laminated on the surface of the metal plate that becomes the outer surface of the container after forming the container. Film laminated metal plate for containers characterized by   The film-laminated metal sheet for containers according to claim 1, wherein the resin film B contains carnauba wax or stearic acid ester as a wax component.   The resin film A and / or the resin film B is a biaxially stretched polyester film in which a relaxation time T1ρ of 1,4-coordinated benzene ring carbon in a structural analysis by solid high-resolution NMR is 150 msec or more. Item 3. The film-laminated metal plate for containers according to Item 1 or 2.   The film-laminated metal sheet for containers according to any one of claims 1 to 3, wherein 90 mol% or more of the polyester units constituting the resin film A and / or the resin film B are ethylene terephthalate units.   Resin film A and / or resin film B is composed of at least two layers, and the intrinsic viscosity difference between the laminate layer in contact with the metal plate and each of the other layers excluding this layer is 0.01 to 0.5. The film-laminated metal plate for containers according to any one of claims 1 to 4.   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.   A can body and / or a lid for a can container obtained by processing the film laminate metal plate for containers according to any one of claims 1 to 6, wherein the container inner surface is a laminate surface of the resin film B, A can container member, wherein the outer surface side of the container is a laminate surface of a resin film A.   A can container obtained by processing the film-laminated metal plate for a container according to any one of claims 1 to 6, wherein the container inner surface side is a laminate surface of the resin film B, and the container outer surface side is a laminate of the resin film A A can container characterized by being a surface.

Images