JP2002347169A - Laminated sheet and coated seamless can using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminated sheet for manufacturing a can which has excellent processability, adhesiveness and corrosion resistance even though it contains pigment, and a coated seamless can using the sheet which has excellent dent resistance. SOLUTION: In this laminated sheet which is manufactured by laminating a resin film in which pigment content is 5-30 wt.% on a metal sheet, birefringence (Δn1 ) of a film part contacting to the metal plate is smaller than the birefringence (Δn2 ) of a part on a film front face side and is 0.08 or less, provided that Δn=nm-nt, wherein nm is reflective index in the maximum orientation direction of the film, and nt is the reflective index in a thickness direction of the film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated plate for can making and a coated seamless can using the laminated plate. Excellent,
In addition, the present invention relates to a laminated plate for can making with less cracking of a film during processing and a coated seamless can having excellent dent resistance obtained by using this laminated plate.

[0002]

2. Description of the Related Art Conventionally, as a side seamless can (side seamless can), a metal material such as an aluminum plate, a tin plate or a tin-free steel plate is provided by at least one step between a drawing die and a punch. By drawing, a cup consisting of a body part having no side seam and a bottom part connected to the body part without a seam is formed, and then, if desired, an ironing punch and a die are formed on the body part. It is known that the body of the container is thinned by ironing between them.
In addition, instead of ironing, a thin drawing forming method in which a side wall portion is thinned by bending and stretching at a curvature corner portion of a redrawing die is already known (Japanese Patent Publication No. 56-501442).

As an organic coating method for a side seamless can, there is known a method of laminating a resin film on a metal material before molding in advance. Japanese Patent Publication No. 59-34580 discloses that a metal material is terephthalic acid. It is described that a laminate obtained by laminating a polyester film derived from and tetramethylene glycol is used.

[0004] It is also known to produce a seamless can in which a pigment is previously contained in an outer surface coating resin film.
No. 0 discloses a clear polyester-based molecular orientation film layer / adhesive / surface-treated steel sheet / adhesive /
Titanium dioxide-containing polyester molecular orientation film layer /
Seamless can and clear polyester-based molecular orientation film layer consisting of a laminate of printing ink layer / finish varnish layer / adhesive / surface treated aluminum alloy plate / adhesive / polyester molecular orientation film layer containing titanium dioxide / printing ink layer /
Each described is a seamless can comprising a laminate of finishing varnish layers.

[0005] The titanium dioxide-containing polyester film layer present on the outer surface of the seamless can hides the chromium surface treatment layer, raises the printing ink layer, and transmits wrinkle pressing force during redrawing or thinning drawing. , The desired action such as preventing the generation of wrinkles in the can body and assisting the rust-preventive force was found, but it was found that the following problems still existed.

That is, in order to increase the hiding power of the pigment particle-containing resin outer layer, it is necessary to increase the content of pigment particles such as titanium dioxide. However, when the content of pigment particles is increased, draw molding or ironing is performed. In molding, there is a disadvantage that adhesion and workability are inferior, and this tendency becomes more remarkable as the thickness of the can body is increased in order to save material and reduce weight.

On the other hand, an important practical property of cans is dent resistance. In this denting test, an impact such as dents is applied to the cans. This test tests whether or not the coating of the can body is completely maintained.However, in the case of actual canned products, impacts due to dropping, collision between cans, etc. often occur, so that the coating is also peeled off in this case. It is also required that a coating film such as a crack or a pinhole does not occur. In particular,
In a seamless can made by squeezing and thinning a resin-coated laminate plate, dents are likely to occur due to impact, and in many cases, the coated resin film is stretched, resulting in poor adhesion, especially dent resistance. It becomes a problem.

[0008]

However, according to the above-mentioned prior art, although the abrasion of the outer layer resin film is considerably reduced, the laminating plate having the coating layer containing a large amount of the pigment has a problem that the pigment particles are not removed. Due to the presence, molecular orientation is likely to occur, which causes a problem that processability and adhesion are reduced. Increasing the orientation of the resin film in the laminate film is effective in improving the barrier properties against corrosive components and improving the corrosion resistance, but on the other hand, it increases brittleness and decreases workability and adhesion. ,
Impact resistance such as dent resistance when a seamless can is formed tends to decrease.

In general, the degree of molecular orientation of a resin coating is measured by measuring the birefringence distribution in the thickness direction of the resin film. However, for a laminate coated with a pigment particle-containing resin film, Because the pigment particles containing light do not transmit light, the measurement of birefringence was difficult, so depending on how to set the birefringence distribution in the thickness direction of the pigment particle-containing resin film, excellent processability and adhesion were achieved. It was unknown whether an excellent laminate could be obtained.
The present inventors have also found that the pigment particle-containing film can be measured for birefringence by a method described in detail later, and further set the birefringence of a portion of the film in contact with the metal plate within a certain range. As a result, it has been found that a laminate for cans having excellent workability, adhesion and corrosion resistance can be obtained. Accordingly, an object of the present invention is to provide a laminate for cans, which contains a pigment but is excellent in processability, adhesion and corrosion resistance during can manufacture, and a coating having excellent dent resistance using the same. We provide seamless cans.

[0010]

According to the present invention, there is provided a laminated plate for a can made by laminating a resin film having a pigment content of 5 to 30% by weight on a metal plate. The birefringence (Δn ₁ ) is smaller than the birefringence (Δn ₂ ) of the portion on the film surface side, and is less than 0.1.
08 or less is provided. In the present specification, the birefringence of a film of a laminate plate is represented by the following formula (1): Δn = nm−nt (1) where nm is a refractive index in the maximum orientation direction of the film;
nt is the refractive index in the thickness direction of the film. Note that the measurement of birefringence is based on the above principle, but in an actual measurement, the above difference is directly obtained. In the laminated plate for cans of the present invention, the birefringence (Δn ₃ ) of the portion on the film surface side is 0.01 to 0.5.
It is preferably 12. Further, an intermediate portion having different birefringence exists between the film surface side portion and the film portion in contact with the metal plate, and the intermediate portion has a birefringence (Δn).
₃ ) may be 0.01 to 0.12.

According to the present invention, there is further provided a coated seamless can characterized by being formed by drawing or ironing the laminated plate for can making. The birefringence of the coated seamless can of the present invention is represented by the following formula (2): Δn = nh−nt (2) where nh is the refractive index in the length direction of the film, and nt is the refractive index in the thickness direction of the film. Which is defined by In this coated seamless can, the birefringence (Δn ₄ ) of the film portion in contact with the metal plate is preferably smaller than the birefringence (Δn ₅ ) of the portion on the film surface side and in the range of 0.10 or less. it is preferable birefringence part of the film surface side ([Delta] n ₅₎ is 0.01 to 0.16. Further, an intermediate portion having a different birefringence value exists between the portion on the film surface side and the film portion in contact with the metal plate, and the intermediate portion has a birefringence (Δn ₆ ) of 0.01 to 0.
There are also 16 cases. Further, at the upper portion of the can side wall of the seamless can, there is at least one birefringence peak near the film portion in contact with the metal plate, and the peak value (Δn
₇ ) is preferably from 0.02 to 0.16. Furthermore, there is provided a coated seamless can characterized in that the side wall portion of the can is reduced to 30 to 90% of the original thickness of the laminated laminate plate during drawing or ironing.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [Action] In the laminated plate for cans of the present invention, the single-layer resin film laminated on the metal plate contains a pigment in an amount of 5 to 30% by weight, and the single-layer resin Birefringence of the part of the film in contact with the metal plate (Δ
It is an important feature that n ₁ ) is smaller than the birefringence (Δn ₂ ) of the portion on the film surface side and not more than 0.08. That is, in the present invention, it is possible to measure the birefringence of a pigment-containing resin film, which has been difficult to measure in the past, and this birefringence is as small as 0.08 or less in a portion in contact with a metal plate of a resin film. The laminate board is
It was found that the moldability and the adhesion of the resin coating were excellent, and further, the dent resistance when the can-made laminate was made into a seamless can was excellent. The birefringence in question in the present invention has a close relationship with the molecular orientation in the film, and this molecular orientation has an amorphous orientation in addition to what is called an oriented crystal. The required birefringence is related to these totals.

It has already been pointed out that it is necessary to increase the concentration of pigment particles in the resin in order to increase the hiding power of the metal plate by covering the surface of the resin. By blending the pigment in an amount of 5 to 30% by weight with the resin film to be the outer or inner surface of the above, a satisfactory hiding power can be obtained. When the amount of the pigment is less than the above range, the hiding power is insufficient. On the other hand, when the amount of the pigment is more than the above range, the film may be broken during laminating operation or the film may be scraped during can making, which is not preferable.

Please refer to the attached drawing FIG. FIG. 1 is a plot of the relationship between the amount of titanium oxide and the stress in a tensile test of a resin film. The results show that as the content of titanium dioxide increases, the stress decreases. If the strength of the film is lower than a certain standard, the film breaks at the time of lamination, and the productivity is undesirably reduced.

On the other hand, when the content of the pigment particles is less than 5% by weight, the chromium surface-treated layer obtained by containing the pigment particles is concealed and the transmission of the wrinkle suppressing force at the time of redrawing is performed. It is not possible to obtain the desired effects such as preventing the occurrence of wrinkles in the can body and assisting the rust-preventive force or raising the printing ink layer on the outer surface.

In the present invention, the measurement of birefringence of a resin film containing pigment particles, which has been difficult to measure conventionally, can be performed by the following method. FIG.
Is a flowchart showing the measurement principle.

"Method of preparing sample and measuring birefringence"
Hereinafter, a method for preparing a sample piece and a method for measuring birefringence used in the present invention will be described, but it is needless to say that the present invention is not limited thereto. First, from the laminated plate, cut out a 100 mm square material centered on the position that should be the can bottom center after molding, and from the top of the can side wall, on the axis in the direction perpendicular to the rolling direction of the metal plate, In addition, a material having a size of about 10 mm square was cut out around a point 5 mm from the tip of the flange portion of the can, and each was sampled as a material for preparing a sample piece. For each of the cut samples, the metal plate was dissolved with hydrochloric acid having a concentration of about 20%, and the film was isolated. Thereafter, the film was vacuum dried for at least 24 hours. Next, the film obtained from the laminate plate and the side wall of the can was embedded with an epoxy resin. Thereafter, the thickness direction of the film and the maximum orientation direction of the film surface are parallel to each other for the film obtained from the laminated plate, and the thickness direction and the can length of the film obtained from the upper portion of the side wall of the can. Each sample was sliced while being embedded so that the directions were parallel to each other to obtain a sample piece. The slice thickness was 1-3 μm, and the setting of the thickness was changed as needed depending on the sample. The slice thickness was set to be relatively small for films having a large content of titanium dioxide and films expected to have a large value of birefringence. The method of measuring the birefringence in the film thickness direction of the cross section of the sliced sample piece will be described below. The birefringence can be calculated by determining the retardation R (nm) of the film thickness direction portion of each sample piece by a general birefringence measurement method using a polarizing microscope. The sample piece is placed at the subtraction position with respect to the compensator with the polarization directions of the polarization obtained by the polarizer and analyzer of the polarization microscope orthogonal to each other (orthogonal Nicols), and the monochromatic light with the measurement wavelength λ = 546 nm is used as the incident light. Then, rotate the analyzer so that the polarization microscope image of the measurement portion becomes the darkest. Assuming that the rotation angle of the analyzer at this time is θ degrees, the retardation R (nm) is expressed by the following equation (A).
Can be obtained from R = λ × θ / 180 (A) From this, birefringence of the film obtained from the laminate plate
(nm-nt) and the birefringence (nh-nt) of the film obtained from the upper portion of the can side wall can be calculated from the equations (B) and (C), respectively. (nm−nt) = R / d = λ × θ / d / 180 (B) (nh−nt) = R / d = λ × θ / d / 180 (C) where d Is the slice thickness (nm). In the measurement of birefringence in the present invention, the birefringence of an object, which includes a CCD microscope, a computer, and image processing software and data processing software operating on the computer in addition to a polarizing microscope, is automatically determined by computer image processing. The measurement was carried out by a system capable of measuring at a time. FIG. 2 shows a flowchart of a birefringence measurement method using this system. The macro program shown in the figure links the image processing software and the data processing software to automatically execute the input of the polarization microscope image to the computer, a series of data processing, the calculation of birefringence, and the like. . Hereinafter, an outline of the processing of the present measurement system will be described.
First, the analyzer of the polarizing microscope is rotated at a predetermined fixed pitch in a range of 0 to 180 degrees in a predetermined measurement range of the sample piece in the film thickness direction, and a polarizing microscope image at each rotation angle is obtained by a CCD camera. To the computer sequentially. Each image input to the computer is converted into a brightness value by the image processing software. Next, the rotation angle of the analyzer at which the polarization microscope image becomes the darkest (the brightness value becomes the minimum) in the measurement range of the sample piece in the film thickness direction is obtained by the data processing software, and the above-described equation (A) is obtained from this. )
And the birefringence is calculated based on the calculation method shown in Expression (B) or Expression (C). The main device names and software names that constitute the measurement system are as shown below.
It is needless to say that the birefringence can also be measured by visually observing an image of a polarizing microscope without using this system.・ Polarization microscope: OPTIPHOT2-POL manufactured by Nikon Corporation (using a Senarumon type compensator) ・ CCD camera: CC-990 manufactured by FLOVEL ・ Computer: FMV-5133D5 manufactured by Fujitsu Ltd. ・ Image processing software: Ima manufactured by Media Cybernetics
ge-Pro PLUS-Data processing software: In measuring the birefringence of an Excel sample from Microsoft, five points were measured and the average value was determined and used as the measured value. Each measurement value may include a value that is clearly judged to be an abnormal value due to scratches generated during slicing or derived from titanium oxide contained in the film, etc. The results obtained by removing abnormal values by observing and judging from measured values before and after the abnormal values were adopted.

[0018] In the laminated plate of the present invention, it is possible to obtain the birefringent by the measuring method, the birefringence of the birefringent ([Delta] n ₁₎ is the film surface side portion of the film portion in contact with the metal plate side ([Delta] n ₂ ) And less than 0.0
It is an important feature that it is 8 or less, especially 0.06 or less. That is, when the birefringence of the film portion in contact with the metal plate side is within the above range, therefore, the adhesiveness and workability with the metal plate are excellent, and the adhesiveness and dent resistance when a seamless can is obtained are improved. Things. This will be clearer with reference to the examples below.

Further, in the laminated plate of the present invention, the birefringence (Δn ₂ ) of the portion on the film surface side is particularly 0.02.
It is preferably from 1 to 0.12, particularly preferably from 0.02 to 0.12. As described above, increasing the orientation of the laminate film is effective in improving the barrier property against corrosive components and improving the corrosion resistance, so that only the film surface side particularly involved in the barrier property is as described above. By having birefringence, it is possible to achieve both excellent workability, adhesion and dent resistance of the film portion in contact with the metal plate side, and corrosion resistance on the surface side.
FIG. 3 is a diagram showing the thickness direction distribution of the birefringence of the pigment particle-containing film layer in one example of the laminated plate of the present invention. It will be appreciated that the refraction has a small value. Further, FIG. 4 is a diagram showing the thickness direction distribution of the birefringence of the pigment particle-containing film layer in another example of the laminate plate of the present invention. It will be understood that, in addition to the small value of the birefringence at the contact portion, there is an intermediate region where the birefringence peaks and shows a maximum value. The intermediate region where the birefringence shows a peak is considered to be useful as a barrier against corrosion components.

The coated seamless can of the present invention is obtained by drawing and redrawing, thinning drawing, or ironing the above laminated sheet for can making. In this coated seamless can, a film portion in contact with the metal plate side is formed. Birefringence (Δ
n ₄ ) is preferably smaller than the birefringence (Δn ₅ ) of the portion on the film surface side and 0.1 or less. Due to this feature, in this seamless can, an advantage that the adhesion of the film after processing is excellent and the seamless can has excellent dent resistance is achieved. In particular, in the present invention, the birefringence (Δn ₅ ) of the portion on the film surface side is 0.0
It is preferably from 1 to 0.16 from the viewpoint of corrosion resistance. FIG. 5 is a view showing the thickness direction distribution of the birefringence of the pigment-containing film for an example of the coated seamless can of the present invention.
As in the case of FIG. 3, it can be understood that the birefringence is large on the surface side of the film, and the birefringence is small at the portion in contact with the metal plate. Further, FIG. 6 is a diagram showing the thickness direction distribution of the birefringence of the pigment particle-containing film layer in another example of the coated seamless can of the present invention. It can be understood that, in addition to the small value of the birefringence at the portion contacting with the metal plate, there is an intermediate region where the birefringence peaks and has a maximum value near the portion contacting the metal plate. Also,
It is considered that the intermediate region where the birefringence shows a peak serves as a barrier against corrosion components. In the coated seamless can of the present invention, as a result of plastic flow such that the dimension increases in the height direction of the can and the dimension decreases in the circumferential direction of the can by drawing or ironing, the orientation is larger than that of the laminate plate. However, since the orientation is relaxed in the heat treatment process during can-making, the birefringence is suppressed to a low range at the part in contact with the metal plate, and the adhesion and corrosion resistance to the metal plate are excellent, and the dent resistance is high. It is also excellent in nature.

[Embodiment] In FIG. 7, which shows an example of the cross-sectional structure of the laminated plate of the present invention, this laminated plate 1
Is composed of a metal plate 2 and a resin film layer 3 having a pigment content of 5 to 30% by weight applied to a surface of the metal plate which becomes an outer surface or an inner surface of the can. The resin film layer 4 is formed on the surface side. The resin film layer 4 may be a clear resin film layer or a pigment-containing resin film layer.
Although not shown, a resin film layer 3 may be provided on each side of the metal plate 2 that becomes the outer surface and the inner surface of the can.

(Metal Sheet) In the present invention, various metal sheets such as surface-treated steel sheets and aluminum are used as the metal sheet. As the surface-treated steel sheet, a cold-rolled steel sheet is subjected to one or two or more surface treatments such as annealing, secondary cold-rolling, zinc plating, tin plating, nickel plating, electrolytic chromic acid treatment, and chromic acid treatment. Can be used. An example of a suitable surface-treated steel sheet is an electrolytic chromic acid-treated steel sheet, particularly a metal chromium layer of 10 to 200 mg / m ^{2 and} a metal chromium layer of 1 to 5 mg / m ^2.
It is provided with a chromium oxide layer of 0 mg / m ² (in terms of chromium metal), and is excellent in combination of coating film adhesion and corrosion resistance. Another example of the surface-treated steel sheet is 0.
It is a hard tin plate having a tin plating amount of 5 to 11.2 g / m ² . This tin plate is desirably subjected to a chromic acid treatment or a chromic acid-phosphoric acid treatment such that the amount of chromium is 1 to 30 mg / m ^{2 in} terms of metal chromium.

As still another example, an aluminum-coated steel sheet subjected to aluminum plating, aluminum pressure welding, or the like is used. As the light metal plate, an aluminum alloy plate is used in addition to a so-called aluminum plate. An aluminum alloy sheet excellent in corrosion resistance and workability is Mn:
0.2 to 1.5% by weight, Mg: 0.8 to 5% by weight,
Zn: 0.25 to 0.3% by weight, and Cu: 0.15
To 0.25% by weight, with the balance being Al. It is desirable that these light metal plates are also subjected to chromic acid treatment or chromic acid / phosphoric acid treatment so that the amount of chromium becomes 20 to 300 mg / m ^{2 in} terms of chromium metal. Further, the surface may be treated with a chemical conversion film containing zirconium or titanium oxide as a main component or a composite film of polyacrylic acid-zirconium salt. The amount of the film is preferably about 5 to 300 mg / m ² as a solid content. The thickness of the metal plate, that is, the thickness of the bottom of the can (tB
) Varies depending on the type of metal, the use or size of the container, but generally has a thickness of 0.10 to 0.50 mm. Among them, in the case of a surface-treated steel sheet, 0.10 to 0. The thickness is preferably 30 mm, or 0.15 to 0.40 mm in the case of a light metal plate.

(Pigment) In the present invention, the content of the pigment to be contained in the resin film is preferably in the range of 5 to 30% by weight as described above. When the content of the pigment is less than 5% by weight, the surface of the metal plate is concealed to improve the transmission of the wrinkle pressing force at the time of squeezing and re-drawing, thereby preventing the occurrence of wrinkles on the can body and assisting the rust prevention power. Also, on the outer surface, it is not possible to obtain a desired effect such as raising the printing ink layer. On the other hand, when the content of the pigment exceeds 30% by weight, the strength of the film decreases, and the film breaks at the time of forming into a seamless can.

Suitable examples of pigments (pigments) that can be contained in the resin film of the laminate of the present invention are as follows. Black pigments Carbon black, acetylene black, run black, aniline black. Yellow pigment Yellow lead, zinc yellow, cadmium yellow, yellow iron oxide, mineral fast yellow, nickel titanium yellow, navels yellow, naphthol yellow S, Hanza yellow G, Hanza yellow 10G, benzidine yellow G,
Benzidine Yellow GR, Quinoline Yellow Lake, Permanent Yellow NCG, Tartrazine Lake. Orange pigments Red mouth lead, molybdenum orange, permanent orange GTR, pyrazolone orange, Vulcan orange, induslen brilliant orange RK, benzidine orange G, induslen brilliant orange GK. Red pigment Bengala, cadmium red, lead red, cadmium mercury sulfide, permanent red 4R, lithol red, pyrazolone red, watching red calcium salt, lake red D, brilliant carmine 6B, eosin lake, rhodamine lake B, alizarin lake, brilliant carmine 3B. Purple pigment Manganese purple, fast violet B, methyl violet lake. Blue pigment Navy blue, cobalt blue, alkali blue lake, Victoria blue lake, phthalocyanine blue, metal-free phthalocyanine blue, partially chlorinated phthalocyanine blue, first sky blue, indaslen blue B
C. Green pigment chrome green, chromium oxide, pigment green B,
Malachite Green Lake, Fanal Yellow Green G. White pigments zinc white, titanium dioxide, antimony white, zinc sulfide. Extender barite powder, barium carbonate, clay, silica, white carbon, talc, alumina white.

The particle size of the pigment is generally 0.1 to 2.5 μm.
m, particularly preferably 0.1 to 2.0 μm.
That is, if the particle size is too large, the drawability tends to be poor, while if the particle size is too small, the hiding power tends to decrease. Particularly suitable pigments for the purposes of the present invention are titanium dioxides, in particular of the rutile or anatase type, which are white and have great hiding power. Titanium dioxide is also excellent in rust prevention.

(Resin Film) In the present invention, as long as the resin film to be laminated on the metal plate contains a predetermined amount of the pigment, a conventionally known resin film such as a polyester film, a polyolefin film, a polyamide film, etc. Can be used, and among them, a thermoplastic polyester resin can be preferably used. As the polyester-based resin, ethylene terephthalate, ethylene isophthalate, butylene terephthalate, butylene is a polyester mainly containing at least one ester unit selected from the group consisting of isophthalate and ethylene naphthalate, drawability, It is preferable in terms of drawability, ironing workability, mechanical strength, corrosion resistance, heat resistance and the like. This polyester is a homopolyester, two or more of the above ester units, or one or more of the above ester units. And at least one other ester unit, or a blend of two or more of these polyesters.

The polyester resin used in the present invention is generally preferably a homopolyester or a copolyester derived from a dibasic acid mainly composed of terephthalic acid and a diol mainly composed of ethylene glycol.

Acid components other than terephthalic acid include isophthalic acid, P-β-oxyethoxybenzoic acid, naphthalene-2,6-dicarboxylic acid, diphenoxyethane-4,
Dibasic acids such as 4′-dicarboxylic acid, 5-sodium sulfoisophthalic acid, hexahydroterephthalic acid, adipic acid, sebacic acid, trimellitic acid, pyromellitic acid, hemi-mellitic acid, 1,1,2,2- Ethanetetracarboxylic acid, 1,1,2-ethanetricarboxylic acid, 1,
3,5-pentanetricarboxylic acid, 1,2,3,4-cyclopentanetetracarboxylic acid, biphenyl-3,4
Examples include polybasic acids such as 3 ′, 4′-tetracarboxylic acid. Of course, these may be used alone or in combination of two or more.

The alcohol components other than ethylene glycol include propylene glycol, 1,4-butanediol, neopentyl glycol, 1,6-hexylene glycol, diethylene glycol, triethylene glycol, cyclohexane dimethanol, and ethylene of bisphenol A. Diols such as oxide adducts,
Examples include polyhydric alcohols such as pentaerythritol, glycerol, trimethylolpropane, 1,2,6-hexanetriol, sorbitol, and 1,1,4,4-tetrakis (hydroxymethyl) cyclohexane. Of course, these may be used alone or in combination of two or more.

As the diol component of the copolymerized polyester, those mainly composed of ethylene glycol are preferred.
It is advantageous from the mechanical properties that 95 mol% or more, especially 98 mol% or more of the diol component is composed of ethylene glycol.

These homopolyesters or copolyesters should have a molecular weight in the range of forming a film, and have an intrinsic viscosity [IV] of 0.5 to 1 when measured using a phenol / tetrachloroethane mixed solvent as a solvent. 5, preferably in the range of 0.6 to 1.5.

Suitable copolyesters are, on average, 98 to 80% terephthalic acid and 2 to 20 isophthalic acid.
%. The average means that the polyester film may be a blend of a plurality of copolyesters having different isophthalic acid contents or a laminate of a plurality of copolyesters having different isophthalic acid contents. It means that it may be a film. The melting point of the copolymerized polyester is preferably in the range of 180 to 270 ° C.

The pigment-containing resin film layer used in the present invention is preferably biaxially stretched, and has a thickness of 2
It is preferably in the range of 5 to 50 μm, especially 5 to 50 μm. When the thickness is smaller than the above range, the corrosion resistance is not sufficient. On the other hand, when the thickness is larger than the above range, the drawability tends to decrease. The degree of biaxial stretching of the pigment-containing resin film, the stretching ratio in the longitudinal direction is 2 to 5 times,
The stretching ratio in the transverse direction is preferably in the range of 2 to 5 times. The film is preferably heat-set after stretching. The heat-setting temperature (Th) varies depending on the melting point of the resin and the amount of the pigment to be mixed.
Preferably, it is heat set at a temperature of 0 ° C. As the pigment-containing resin film layer used in the present invention, the resin may be extruded in a molten state or may be an unstretched film (cast film). From the viewpoint, the biaxially stretched film is preferable.

(Production Method of Laminated Plate) In the production of a laminated plate using a biaxially stretched film, generally, a metal plate is heated to a temperature (T ₁ ) higher than the melting point (Tm) of a resin film used by a heating roll or the like. It is performed by supplying between the laminating rolls. On the other hand, the stretched resin film is unwound from a supply roll and supplied in a positional relationship of sandwiching a metal plate between laminate rolls adjusted to a predetermined temperature (T ₂ ) to thermally bond the film to the surface of the metal plate. Let it. A water tank containing cooling water for quenching the laminate to be formed is provided below the laminating roll, and a guide roller for guiding the laminating is disposed in the water tank, and the laminate discharged from the laminating roll is guided into the cooling water. And quench. The heating temperature (T ₁ ) of the metal plate is from Tm-50 ° C. to Tm based on the melting point (Tm) of the resin film.
The temperature within the range of + 50 ° C. is preferable from the viewpoint of obtaining the heat adhesive property and the birefringence property specified in the present invention. On the other hand, the temperature (T ₂ ) of the laminating roll is the heat setting temperature (T
h) lower than the glass transition point (Tg) of the resin film
The above temperature is preferable for the same reason. Birefringence of the resin coating layer of the laminate plate, the type of resin of the film, the content of pigment particles, the degree of molecular orientation of the film, the thickness of the film, the metal plate temperature during lamination,
Since the temperature of the laminating roll at the time of lamination, the cooling rate and the like are significantly different, the conditions for setting the birefringence within the above-described range cannot be unconditionally defined, but can be experimentally determined based on the above temperature. . For example, when the degree of molecular orientation of the biaxially stretched film is high, the temperature of the metal plate is increased to relax the orientation of the film portion that is in contact with the metal plate, so that the film portion that is in contact with the metal plate in the laminate is duplicated. Since the refraction can be suppressed low, the birefringence index can be controlled using such a tendency. More specifically, a certain resin, a certain pigment particle content, a certain degree of molecular orientation,
Examining the metal plate temperature and the birefringence of the laminate film for a film of a certain thickness, there is a one-to-one correspondence between the metal plate temperature and the birefringence of the film that is thermally bonded to it. Thus, the lamination conditions for obtaining a predetermined birefringence can be determined. Since the correspondence between such a factor of the lamination and the birefringence also applies to other than the temperature of the laminating roll, lamination conditions for setting the birefringence within the above-described range can be easily determined by those skilled in the art by simple experiments. .

In the production of a laminated plate by extrusion coating, generally, a metal plate is preheated by a heating device.
It is supplied to a pair of laminate rolls. On the other hand, a resin film is extruded in the form of a thin film from a die head of an extruder arranged on both sides of a metal plate, and supplied between a laminating roll and the metal plate. The laminated plate is obtained by heat bonding and cooling from both sides. Next, the above-mentioned laminated plate is further guided to a cooling water tank or the like to be rapidly cooled.

In the production of a laminated plate from a resin-unstretched film formed in advance, a metal plate is heated by a heating roll and supplied between the laminating rolls, while the resin film is unwound from the supply roll. Are supplied in a positional relationship of sandwiching a metal plate between laminating rolls. The laminating roll is maintained at a slightly higher temperature than the heating roll, and a resin film is thermally bonded to both surfaces of the metal plate to form a laminated plate, which is guided to a cooling water tank below the laminating roll to perform rapid cooling.

In the present invention, a pigment-containing resin film can be directly provided on a metal plate, but a conventionally known adhesive primer layer can be provided between the metal plate and the pigment-containing resin film. This adhesive primer exhibits excellent adhesiveness to both the metal material and the film. Primer coatings with excellent adhesion and corrosion resistance include phenol-epoxy coatings composed of resole-type phenolaldehyde resins derived from various phenols and formaldehyde, and bisphenol-type epoxy resins. 5 resin
It is a coating composition containing at a weight ratio of 0:50 to 1:99, particularly at a weight ratio of 40:60 to 5:95. The adhesive primer layer is generally preferably provided with a thickness of 0.01 to 10 μm. The adhesive primer layer may be provided on a metal material in advance, or may be provided on a pigment-containing resin film. Although not generally required, when using an adhesive primer,
It is generally desirable that the surface of the resin film be subjected to a corona discharge treatment in order to increase the adhesiveness with the adhesive primer to the film. It is desirable that the degree of the corona discharge treatment is such that the wetting tension is 40 dyne / cm or more. In addition, plasma treatment of the film,
It is also possible to carry out a known surface treatment for improving the adhesiveness such as a flame treatment or a coating treatment for improving the adhesiveness of a urethane resin or a modified polyester resin.

The resin film may be blended with known film compounding agents, various antistatic agents, lubricants, and the like according to known formulations.

As another resin layer provided on the inner side of the can, a similar polyester film containing or not containing a pigment is used. This film may be a single-layer film or a laminated film.

(Manufacture of Seamless Can) The metal can comprising the laminated plate for can-making of the present invention has the excellent properties of the laminated plate as long as it is formed from the above-described laminated plate for can-making. Although it can be manufactured by a can manufacturing method and can be a three-piece can having a side seam,
In particular, a seamless can is preferable. The seamless can (two-piece can) composed of the laminated plate of the present invention is drawn and re-wrung, drawn and drawn so that the coating surface of the pigment-containing resin film of the above-mentioned laminated plate is on the outer surface side of the can and / or the inner surface side of the can. It is manufactured by a conventionally known means such as bending and stretching by thinning (thinning or stretching), bending and stretching by drawing and redrawing, or drawing and ironing. The seamless can of the present invention is manufactured by the above-mentioned means. Preferably, the side wall is thinned by bending and stretching by redrawing and / or ironing. The thickness of the laminate is reduced by 20 to 95% of the original thickness of the laminate plate by bending and stretching the side wall compared to the bottom and / or by ironing.
In particular, it is preferable that the thickness is reduced so as to have a thickness of 30 to 90%.

The obtained can is subjected to at least one stage of heat treatment to remove residual strain of the film caused by processing.
The lubricant used in the processing is volatilized from the surface, and the printing ink printed on the surface is dried and hardened. The container after the heat treatment is quenched or allowed to cool, and then subjected to a single-stage or multi-stage neck-in process, if necessary, and subjected to a flange process to obtain a can for winding. After the seamless can is formed, the upper portion of the seamless can can be deformed to form a bottle. In the present invention, the heat treatment described above relaxes the orientation of the film portion in contact with the metal plate, and the birefringence (Δn ₄ ) is suppressed to the above-described range. In addition, by this heat treatment, the orientation crystallization is promoted in a portion close to the film portion in contact with the metal plate, and as shown in FIG. 6, the intermediate region where the birefringence peaks and shows a maximum value may be formed. is there. The heat treatment temperature is generally 180
It is preferable to select a temperature such that Δn ₄ falls within the above-mentioned range from the range of 270 ° C. to 270 ° C.

As described above, the laminated plate for cans of the present invention has the same excellent properties as the laminated plate even if it is thinned by drawing and ironing, and the resin coated on the metal plate. From the viewpoint that the film is thinned and the dent resistance is improved even when stretched and oriented, it is particularly suitable for the production of seamless cans, but even when used for three-piece cans and drawn cans, it is the same as a laminated plate And it is possible to express the excellent characteristics of the laminate as it is.

[0044]

EXPERIMENTAL EXAMPLES The present invention will be described with reference to the following examples. The measurement was performed as follows. -Thickness of can side wall portion with respect to base plate thickness When the base plate thickness of the laminated laminate plate is t0 and the thickness of the can side wall portion after molding is t1, the thickness (%) of the can side wall portion with respect to the base plate thickness is t1 / It was determined from t0 × 100. -Storage test A storage test was conducted at a relative humidity of 80% and a temperature of 37 ° C, and the state of the can after three months was examined.

EXPERIMENTAL EXAMPLE 1 An experiment example 1 shown in Table 1 was applied to one surface (a surface to be an outer surface of a container) of tin-free steel (TFS: electrolytic chromic acid-treated steel plate) having a base plate thickness of 0.18 mm and a temper degree of DR-6. A biaxially stretched film of isophthalic acid copolymerized polyethylene terephthalate having a thickness of 17 μm and a melting point of 226 ° C. (stretching ratio: 3.0 times, 3.0 times, heat setting temperature: 180 ° C.) having the structure shown in FIG. On the surface to be the inner surface of the film), a single-layer biaxially stretched film of isophthalic acid copolymerized polyethylene terephthalate having a thickness of 25 μm and a melting point of 226 ° C. (stretching ratio: 3.0 times, 3.0 times wide, heat setting temperature: 180 ° C.) , Plate temperature 235 ° C,
The laminate was thermally laminated at a laminating roll temperature of 160 ° C. and a passing speed of 40 m / min, and immediately cooled with water to obtain a laminated metal plate. A wax-based lubricant was applied to both sides of the laminated metal plate, and a circular blank having a diameter of 166 mm was punched to obtain a shallow drawn cup. Next, the shallow drawn cup was thinned and redrawn and ironed to obtain a deep drawn ironed cup.
The properties of the deep drawn ironing cup were as follows. Cup diameter 60 mm Cup height 128 mm Thickness of the side wall of the can 65% of the original plate thickness
After heat treatment at 215 ° C., the cup was allowed to cool, and then subjected to trimming processing, curved surface printing and baking drying, necking processing, and flanging processing to obtain a 350 g seamless can. The results are shown in Table 1. The moldability was good, the adhesion between the wound part and the neck part was not a problem, and the storage test was good.

Experimental Example 2 An isophthalic acid copolymerized polyethylene terephthalate biaxially stretched film having the constitution shown in Experimental Example 2 in Table 1 was used on the surface to be used as the outer surface at a base plate thickness of 0.190 mm.
Experimental Example 1 except that the temperature of Ramiroll was 0 ° C and the temperature of Ramiroll was 130 ° C
To obtain a laminate plate. A circular blank having a diameter of 163 mm was punched out of the laminated plate, and a 350 g seamless can was obtained in the same manner as in Experimental Example 1 except that the thickness of the can side wall was 50% of the original plate thickness. The results are shown in Table 1. The moldability was good, the adhesion between the wound part and the neck part was not a problem, and the storage test was good.

Experimental Example 3 An isophthalic acid copolymerized polyethylene terephthalate biaxially stretched film having the constitution shown in Experimental Example 3 in Table 1 was used on the surface to be the outer surface, the plate temperature was 235 ° C., and the passing speed was 20 m.
A laminate was obtained in the same manner as in Experimental Example 1 except that the rate was changed to / min. A 350 g seamless can was obtained from this laminated plate so that the thickness of the can side wall was 50% of the original plate thickness in the same manner as in Experimental Example 2. The results are shown in Table 1. Good moldability,
There was no problem in the adhesion between the wound portion and the neck portion, and the storage test was good.

EXPERIMENTAL EXAMPLE 4 A biaxially stretched polyethylene naphthalate / polyethylene terephthalate copolymer having a melting point of 205 ° C. (stretching ratio: 3.0 times, 3.0 times,
A heat-setting temperature of 160 ° C) is applied to a polyethylene naphthalate / polyethylene terephthalate copolymer biaxially stretched film having a melting point of 205 ° C and containing no titanium oxide on the surface to be an inner surface (stretching ratio: 3.0 times, 3.1 times, Heat setting temperature 160
C)), and a laminated plate was obtained in the same manner as in Experimental Example 2 except that the plate temperature was 215 ° C and the laminating roll temperature was 150 ° C. Same as Experimental Example 2 except that the laminated plate was deep drawn and ironed so that the thickness of the can side wall was 50% of the original plate thickness to obtain a cup, and then heat-treated the cup at 190 ° C. To obtain a seamless can for 350 g. The results are shown in Table 1. Although the outer film was slightly scraped during molding, there was no problem in the adhesion between the wound portion and the neck portion, and the results of the storage test showed that the film was within a practical level.

EXPERIMENTAL EXAMPLE 5 The film on the surface to be the outer surface was made of polybutylene terephthalate 30 having a melting point of 235.degree.
Isophthalic acid copolymerized polyethylene terephthalate biaxially stretched film (stretch ratio: 3.5 times, width: 3.times.)
The film on the surface to be used as an inner surface is a biaxially stretched film of isophthalic acid copolymerized polyethylene terephthalate containing 30% by weight of polybutylene terephthalate having a melting point of 235 ° C. and containing no titanium oxide (6 times, heat setting temperature 180 ° C.) Magnification 3.5x, 3.6x, heat setting temperature 180
℃), plate temperature 235 ° C, laminating roll temperature 15
A laminated plate was obtained in the same manner as in Experimental Example 1 except that the temperature was changed to 0 ° C., to obtain a 350 g seamless can. The results are shown in Table 1. The moldability was good, the adhesion between the wound part and the neck part was not a problem, and the storage test was good.

EXPERIMENTAL EXAMPLE 6 An original sheet thickness of 0.210 mm, a sheet temperature of 235.degree. C., a laminating roll temperature of 80.degree. C., and an isophthalic acid having a melting point of 228.degree. A laminated plate was obtained in the same manner as in Experimental Example 1 except that the polymerized polyethylene terephthalate resin was coextruded with 20 μm of isophthalic acid copolymerized polyethylene terephthalate resin having a melting point of 228 ° C. on the inner surface. This laminated plate was punched into a disk having a diameter of 140 mm to obtain a shallow drawn cup. Next, the shallow drawn cup was redrawn and ironed to obtain a deep drawn iron cup. The properties of the deep drawn ironing cup were as follows. Cup diameter 53 mm Cup height 140 mm Can side wall thickness 50% of original plate thickness The same procedure as in Experiment 1 was carried out except that the dimensions were as described above, to obtain a seamless can for 250 g. The heat treatment of the can after molding was performed at 205 ° C. The results are shown in Table 1. The moldability was good, the adhesion between the wound part and the neck part was not a problem, and the storage test was good.

EXPERIMENTAL EXAMPLE 7 The original plate thickness was 0.210 mm, the plate temperature was 245 ° C., the laminating roll temperature was 80 ° C., and the melting point of the structure shown in Experimental Example 7 in Table 1 was prepared in advance on the surface to be the outer surface. Experimental Example 1 except that a cast film of isophthalic acid copolymerized polyethylene terephthalate at 235 ° C. was used, and a cast film of isophthalic acid copolymerized polyethylene terephthalate having a melting point of 235 ° C. prepared beforehand was used on the inner surface.
A laminate was obtained in the same manner as described above. The laminated plate was processed in the same manner as in Experimental Example 6 to obtain a seamless can for 250 g.
The heat treatment of the can after molding was performed at 220 ° C. The results are shown in Table 1. The moldability was good, the adhesion between the wound part and the neck part was not a problem, and the storage test was good.

Experimental Example 8 A laminated plate was obtained in the same manner as in Experimental Example 1, except that the original plate thickness was 0.240 mm, the plate temperature was 245 ° C., the laminating roll temperature was 130 ° C., and the passing speed was 10 m / min. This laminated plate was punched into a disk having a diameter of 143 mm to obtain a shallow drawn cup. Next, the shallow drawn cup was redrawn and ironed to obtain a deep drawn iron cup. The properties of the deep drawn ironing cup were as follows. Cup diameter 52 mm Cup height 112 mm Thickness of the side wall of the can with respect to the original plate thickness 73% The same procedure as in Example 1 was carried out except that this deep-drawn ironing cup was subjected to doming molding for a negative pressure can to obtain a seamless can for 200 g. . The results are shown in Table 1. The moldability was good, the adhesion between the wound part and the neck part was not a problem, and the storage test was good.

Experimental Example 9 A biaxially stretched film of isophthalic acid copolymerized polyethylene terephthalate having a melting point of 226 ° C. having a constitution shown in Experimental Example 9 in Table 1 (having a draw ratio of 3.3 times and a width of 3.times.) Was formed on the surface to be the outer surface.
3 times, heat setting temperature 180 ° C), and a biaxially stretched polyethylene naphthalate / polyethylene terephthalate copolymer film having a melting point of 205 ° C (stretching ratio 3.0 times, 3.0 times in width) is applied to the inner surface. The heat setting temperature was 160 ° C.), and a laminated plate was obtained in the same manner as in Experimental Example 1 except that the plate temperature was 205 ° C., the laminating roll temperature was 80 ° C., and the passing speed was 10 m / min. The laminated plate was processed in the same manner as in Experimental Example 1 to obtain a seamless can for 350 g.

Experimental Example 10 A biaxially stretched film of isophthalic acid copolymerized polyethylene terephthalate having a melting point of 235 ° C. having a constitution shown in Experimental Example 10 in Table 1 (drawing ratio: 3.5 times, 3.6 times, heat setting temperature: 1)
90 ° C.) is used as the outer surface and the inner surface is a polyethylene naphthalate / polyethylene terephthalate copolymer biaxially stretched film having a melting point of 205 ° C. (stretching ratio: 3.0 times, 3.0 times). Plate temperature 210 ° C, laminating roll temperature 80
C., and a laminate was obtained in the same manner as in Experimental Example 1. This laminated plate was processed in the same manner as in Experimental Example 1 to obtain 35
A seamless can for 0 g was obtained. The heat treatment after can making is 2
Performed at 00 ° C. Delamination occurred in the film at the flange portion after the molding, and the heat treatment after the can making further increased the delamination. In the retort heat sterilization treatment after filling the contents, the film was cracked. It was judged that it was not suitable for practical use.

Experimental Example 11 An isophthalic acid copolymerized polyethylene terephthalate biaxially stretched film having the constitution shown in Experimental Example 11 in Table 1 was used on the surface to be the outer surface, the plate temperature was 260 ° C., the laminating roll temperature was 160 ° C. A laminated plate was obtained in the same manner as in Experimental Example 2 except that the plate speed was changed to 10 m / min. This laminated plate was processed in the same manner as in Experimental Example 2 to obtain a seamless can for 350 g. Although molding could be performed, if the can was made continuously, the outer film was easily shaved immediately after the can was made. In the heat treatment of the can after the can-making, fine film cracks (a state of rough skin) occurred near the film surface on the top of the can. The cracked portion of the film not only impaired the appearance, but also had a poor impact resistance. Under the storage test, corrosion under the film was observed in the dent portion generated during transportation of the can. In addition, a fine under-film corrosion occurred at the bottom of the can in the storage test. From these results, it was determined that the composition was not suitable for practical use. In addition, since the film on the upper part of the can can be cracked by the heat treatment of the can, the birefringence data of the upper part of the can in Experimental Example 12 in Table 1 are data before the heat treatment.

Experimental Example 12 An isophthalic acid copolymerized polyethylene terephthalate biaxially stretched film having a melting point of 226 ° C. having a constitution shown in Experimental Example 12 of Table 1 (drawing ratio 3.5 times, 3.6 times, heat setting temperature 1)
80 ° C.) is used for the surface to be the outer surface, and the surface to be the inner surface is a biaxially stretched polyethylene naphthalate / polyethylene terephthalate copolymer having a melting point of 205 ° C. (stretching ratio: 3.0 times, 3.0 times). Plate temperature 210 ° C, laminating roll temperature 80
C., and a laminate was obtained in the same manner as in Experimental Example 1. This laminated plate was processed in the same manner as in Experimental Example 1 to obtain 35
Although a seamless can for 0 g was obtained, many film cracks occurred at the neck. The heat treatment of the can was performed at 200 ° C.
In the storage test, under-film corrosion occurred in the cracked portion of the neck. It was judged that it was not suitable for practical use.

Experimental Example 13 A 350 g seamless can was obtained in the same manner as in Experimental Example 2 except that the heat treatment of the molded can was performed at 250 ° C. In the storage test, under-film corrosion occurred in the dent portion of the neck portion generated during transport of the can. In addition, a fine under-film corrosion occurred at the bottom of the can in the storage test. From these results, it was determined that the composition was not suitable for practical use.

Experimental Example 14 An experiment shown in Table 1 was carried out in which the original plate thickness was 0.210 mm, the plate temperature was 180 ° C., the laminating roll temperature was 80 ° C., the sheet passing speed was 10 m / min, and the surface to be the outer surface was prepared in advance. A cast film of isophthalic acid copolymerized polyethylene terephthalate having a melting point of 230 ° C. having the constitution shown in Example 7 was used, and a cast film of isophthalic acid copolymerized polyethylene terephthalate having a melting point of 230 ° C. prepared beforehand was used on the surface to be the inner surface. A laminated plate was obtained in the same manner as in Experimental Example 1 except for the above. This laminated plate was processed in the same manner as in Experimental Example 7 to obtain 250 g.
A seamless can was obtained. Heat treatment of cans after molding is 200 ° C
I went in. Although the moldability was not a problem, the flange portion slightly delaminated after heat treatment of the can. In addition, the retort heat sterilization treatment after filling the contents caused delamination at the flange tip and neck. Therefore, no storage tests were performed.

Table 1 shows the above results.

[Table 1]

[0060]

According to the laminate for cans of the present invention,
A resin film having a pigment content of 5 to 30% by weight is laminated on a metal plate, and the birefringence (Δn ₁ ) of the film portion in contact with the metal plate is birefringence (Δn) of the portion on the film surface side.
_By being lower than ₂ ) and 0.08 or less, it was possible to provide a laminated plate for cans which contained a pigment but was excellent in processability and adhesion during can-making. In addition, a coated seamless can formed by drawing or ironing the laminated plate for can making has a concealing property,
A coated seamless can excellent in adhesion, impact resistance (dent resistance) and corrosion resistance could be provided.

[Brief description of the drawings]

FIG. 1 is a diagram showing the relationship between the content of titanium dioxide and the strength of a film for a resin-coated metal plate.

FIG. 2 is a flowchart of a birefringence measurement method.

FIG. 3 is a diagram showing a thickness direction distribution of birefringence for an example of the laminated plate of the present invention.

FIG. 4 is a diagram showing a thickness direction distribution of birefringence in another example of the laminated plate of the present invention.

FIG. 5 is a diagram showing a thickness direction distribution of birefringence for an example of the coated seamless can of the present invention.

FIG. 6 is a diagram showing a thickness direction distribution of birefringence in another example of the coated seamless can of the present invention.

FIG. 7 is a diagram showing an example of a cross-sectional structure of a laminate plate of the present invention.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (Reference) B65D 1/12 B65D 8/16 8/16 1/00 BFame (Reference) 3E033 AA06 BA07 BA08 BA09 BA14 BA17 BA18 BA21 BB04 BB05 BB08 CA20 EA10 FA10 3E061 AA15 AB13 BA01 BA02 DA01 4F100 AB01A AB03A AB13A AK01B AK01C AK01D AK42B AK42C AK42D BA03 BA04 BA07 BA10A BA10C BA26 CA13B CA13C J01J02 J01 J02 J01 J02

Claims (9)

[Claims] 1. A laminated plate for a can made by laminating a resin film having a pigment content of 5 to 30% by weight on a metal plate, wherein the birefringence (Δn ₁ ) of the film portion in contact with the metal plate is the film surface. Birefringence (Δ
n ₂₎ smaller than the laminate board, characterized in that and 0.08 or less. Here, Δn = nm−nt (1) nm is the refractive index in the maximum orientation direction of the film, and nt is the refractive index in the thickness direction of the film. 2. Birefringence (Δ) of a portion on the film surface side
n ₂₎ is can-laminate plate according to claim 1, characterized in that a 0.01 to 0.12. 3. An intermediate portion having a different birefringence value exists between a portion on the film surface side and a film portion in contact with the metal plate, and the intermediate portion has a birefringence (Δn ₃ ) of 0.01 to _3.
3. The laminated plate for cans according to claim 1, wherein the thickness is 0.12. 4. 4. A coated seamless can, obtained by drawing or ironing the laminated plate for can-making according to any one of claims 1 to 3. 5. The birefringence (Δn ₄ ) of the film portion in contact with the metal plate in the upper portion of the can side wall of the seamless can is smaller than the birefringence (Δn ₅ ) of the portion on the film surface side and 0.10 or less. 5. The coated seamless can according to claim 4, wherein Δn = nh−nt (2) where nh is the refractive index in the length direction of the film and nt is the refractive index in the thickness direction of the film. 6. A birefringence (Δn ₅ ) of a portion on a film surface side of an upper portion of a side wall of the seamless can is 0.0.
The coated seamless can according to claim 4 or 5, wherein the ratio is from 1 to 0.16. 7. An intermediate portion having a different birefringence value exists between a portion on a film surface side and a film portion in contact with a metal plate at an upper portion of a can side wall of the seamless can, and a birefringence (Δn) of the intermediate portion exists. The coated seamless can according to any one of claims 4 to _{6, wherein 6} ) is 0.01 to 0.16. 8. At least one peak of birefringence near the film portion in contact with the metal plate in the upper portion of the side wall of the seamless can, and the peak value (Δn ₇ )
Is 0.02 to 0.16.
8. The coated seamless can according to any one of items 1 to 7. 9. The coating seamless according to claim 4, wherein the can side wall portion is reduced to 30 to 90% of the original plate thickness of the laminated laminate plate during drawing or ironing. can.