JPH08332527A - Two-piece drawing/ironing can excellent in corrosion resistance and flavor loss resistance and its manufacture - Google Patents

Abstract

PURPOSE: To provide a can free from the peeling off of the resin at a flange part, which is excellent in corrosion resistance and flavor loss resistance. CONSTITUTION: In a drawing/ironing can formed by using a tin-plated steel sheet at least on side of which becoming the inside surface of the can s previously covered with thermoplastic resin, the main component of the thermoplastic resin is crystalline polyester resin, the average thickness of a resin layer in the side wall part of the can is 5 to 30μm, the average thickness of a tin film is 0.2 to 2.0g/m<2> , and the effective covering ratio of the tin is 85% or over. A metallic surface of the whole periphery in contact with the thermoplastic resin covering at least a range within 2mm from the tip of a flange is covered by an iron-tin alloy, and the covering ratio of the iron-tin alloy is 0.7 or over. A two-piece drawing/ironing can excellent in corrosion resistance and a flavor preservability whose part of a range within 2mm from the tip of the flange of a can body is heat-treated and formed of an iron-tin alloy layer is provided as well as is manufacture method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a squeezed ironing can with improved adhesion to a polyester resin coating on a flange portion, which is excellent in corrosion resistance and flavor resistance, and a method for producing the same.

[0002]

2. Description of the Related Art A two-piece can using a tin-plated steel plate has a serious defect that the tin coverage is small and a large number of cans having exposed steel surfaces are produced. The tin coverage of the tin-plated steel sheet itself is large, and even if it is good, the steel surface is exposed at the contacted portion when it contacts the forming tool during forming, and the tin coverage is reduced. In particular, when forming by drawing and ironing, there is a problem that the exposed steel surface becomes large because the amount of processing is large.
For this reason, paint is applied to the inner surface of the can after squeezing and ironing, but with such means, the corrosion resistance and flavor resistance are not sufficient and the occurrence of defects at these points cannot be prevented. In addition, the conventional laminated squeezed drawn and ironed cans are squeezed and ironed, then trimmed, then heat-treated, and then neck and flange processed, resulting in relatively large damage to the inner film, and especially a high necking rate. In that case, there is a problem that the polyester resin inner surface film of the flange portion is easily separated from the metal.

Chemical conversion treatment may be carried out, but the effect is not sufficient and workability is poor. Further, JP-A-60-172637 and JP-A-2-303634, in which a metal plate laminated with a polyester resin is used and the ironing ratio is defined in a specific range, have been proposed. In addition to this, the drawing temperature was set to be near the glass transition point of PET film.
-55055 and JP-B-3-33506 in which a plating layer is provided on a surface-treated coating and a PET coating is provided thereon to regulate the ironing rate within a specific range. However, in all of these prior arts, the adhesion between the tin layer and PET was insufficient, the flavor resistance was insufficient, and the impact strength was also insufficient. Even if specified by the ironing rate, if ironing is performed with a small amount of ironing, pinholes are generated and the steel surface is exposed. Therefore, the ironing rate alone does not improve the flavor. In these prior arts, both the tin-plated layer and the laminated resin layer are controlled by the coating amount, but since the thickness of the coating layer cannot be controlled by such a simple control, a layer having a uniform film thickness cannot be obtained. It is considered that sufficient performance is not exhibited due to the presence of pinholes in the coating layer.

[0004]

DISCLOSURE OF THE INVENTION The present invention provides a can having excellent adhesion between a metal surface and a polyester resin coating layer, and a method for producing the can with high workability.

[0005]

The present invention has solved all the problems by the following means. The present invention relates to: “1. In a drawn and ironed can formed of a tin-plated steel sheet on which at least one inner surface is coated with a thermoplastic resin in advance, the thermoplastic resin is mainly composed of a crystalline polyester resin, and The average thickness of the resin layer is 5 to 3
The average thickness of the tin coating is 0.2 to 2.0 g /
m ² and the effective coverage of tin is 85% or more, and the metal surface in contact with the thermoplastic resin of at least 2 mm from the flange tip is covered with the iron-tin alloy. A two-piece squeezed ironing can with excellent corrosion resistance and flavor, characterized by an alloy coverage of 0.7 or more. 2. A two-piece squeezed ironing can excellent in corrosion resistance and flavor described in item 1, wherein the crystalline polyester resin, which is the main component of the coating resin, has a Tg of 55 ° C. or higher and an intrinsic viscosity (IV) of 0.65 or higher. 3. The effective coverage of tin is 0.1g / m when the thickness of the tin coating is
A two-piece squeezed ironing can that is excellent in corrosion resistance and flavor, as described in item 1 or 2, which is a value indicating the proportion of ^two or more parts. 4. From the amount of alloy tin A and the amount of surface tin B from the flange tip to 2 mm from the flange tip of iron-tin alloy, C = A / (A + B)
Which is the value C obtained by the equation of 2 and is excellent in corrosion resistance and flavor property as described in any one of 1 to 3
Piece squeezed ironing can. 5. The tin-plated steel sheet having a tin-plating thickness of 0.4 to 6.0 g / m ² has a crystallinity of not more than 5% and a thickness of 15 to 9 on the inner surface of the tin.
0 μm, elongation at break 100% or more, Tg 55 ° C or more,
A thermoplastic resin coating having an intrinsic viscosity (IV) of 0.65 or more is arranged, and a cup is formed by drawing once or more, and heat treatment is performed from a flange tip of a can body to a portion that should be at least 2 mm. If necessary, further redraw, and then perform ironing with a punch and an ironing die with an entry angle of 2 to 8 degrees, and immediately after the final ironing process, cool to obtain the average thickness of the resin layer on the side wall of the can. Is 5 to 30 μm, and the average thickness of the tin coating is 0.2 to 2.0.
g / m ² , the effective coating rate of tin is 85% or more, and the metal surface in contact with the thermoplastic resin on the entire circumference of at least 2 mm from the flange tip is coated with the iron-tin alloy.
A method for producing a two-piece squeezed ironing can, which has a tin alloy coverage of 0.7 or more and is excellent in corrosion resistance and flavor. 6. At the time of molding, the temperature of the tin layer on the inner surface of the cup was maintained at a temperature not exceeding 232 ° C., and after the final ironing, it was rapidly cooled to set the tin temperature on the inner surface of the necking portion and the flange portion to 232.
A method for producing a two-piece squeezed and ironed can having excellent corrosion resistance and flavor properties as described in item 5, which is kept at ℃ or below. 7. A thermoplastic resin coating containing a polyester resin as a main component is squeezed and oriented and crystallized in the step of ironing, which is excellent in corrosion resistance and flavor as described in 5 or 6.
Manufacturing method of piece squeezing ironing can. Regarding

[0006]

The first feature of the present invention is that the adhesion between the metal and the polyester resin coating is improved to improve the corrosion resistance. As described above, when the tin-plated steel sheet is squeezed and ironed and then neck flange processing is performed, if the degree of processing is large, the tin-plated layer and the polyester resin coating are separated.
This is because the adhesion between the tin-plated layer and the polyester resin coating is not good. In particular, the peeling is likely to occur from the tip of the flange up to about 2 mm. In the present invention, the peeling of the polyester resin coating is prevented by coating the metal surface of the entire circumference of at least 2 mm from the tip of the flange where peeling occurs with the iron-tin alloy. The iron-tin alloy has a better adhesion of the polyester resin coating than the tin-plated layer and has a great effect of preventing peeling.

The iron-tin alloy coating must be provided on the entire circumference with a width of at least 2 mm from the flange tip. Two
If it is less than mm, peeling during drawing cannot be prevented. Further, unless the iron-tin alloy coating rate over the entire circumference of at least 2 mm from the tip of the flange is 0.70 or more, a sufficient peeling effect is not exhibited. The coverage C of the iron-tin alloy is JIS G 330 for a tin-plated steel plate 2 mm from the flange tip.
According to the tin adhesion amount test method and electrolytic peeling method of 3 tinplate, the alloy tin amount A and the surface tin amount B were measured, and C = A / (A + B)
It is the value obtained by. To form the iron-tin alloy coating, the tin plating layer can be alloyed by heating the cup edge to about 230 ° C. or higher in the cup state obtained by drawing.

As described above, the can of the present invention is manufactured by alloying the cup edge portion, further drawing and ironing. Further, the can of the present invention is provided with a portion 2 mm or more from the tip of the cup, which is to be a flange after drawing and ironing.
It can also be obtained by heating to ℃ or more. The effective coverage of tin is the proportion occupied by the portion where the thickness of the tin layer is 0.1 g / m ² or more, and when it is 85% or less, under-film corrosion occurs and corrosion resistance deteriorates even if there is a tin layer. The feature of the present invention is a can in which a tin-plated surface is coated with a thermoplastic resin and is squeezed and ironed. The thickness of the resin layer on the side wall of the can is 5 to 30 μm, and the average thickness of the tin coating film is 0. Two
It is to be 2.0 g / m ² and the effective tin coverage is 85% or more, so that the can has significantly improved corrosion resistance.

The reason why the steel surface is not exposed in the tin layer when the thermoplastic resin is laminated on the tin-plated layer and drawn and ironed is formed. The reason for this is that the processing tool directly touches the tin-plated layer. Since the thermoplastic resin acts as a cushioning material and transmits the processing force to the tin layer while the resin itself is being molded, the processing force of the spreading is not applied rapidly to the tin layer and the spreading is impossible. I think it will be done without. Therefore, the thermoplastic resin to be laminated is preferably one having good workability, and a crystalline polyester resin is suitable.

The second effect of the present invention is that the flavor property is good. When the aroma component of the contents is adsorbed on the inner surface material of the can, the flavor of the contents changes. Further, even if the material on the inner surface of the can is dissolved in the contents, the flavor of the contents changes. As described above, the flavoring property is caused not only by the exposed steel plate of the tin-plated layer but also by the coated resin. According to the study of the present inventors, when a crystalline polyester resin having a Tg of 55 ° C. or more and an intrinsic viscosity (IV) of 0.65 or more is used as a thermoplastic resin for forming a laminate layer on a tin layer on a side wall of a can, It was found that the sorption amount of the flavor component was significantly reduced, and the isophthalic acid-based copolyester resin was particularly preferable.

In addition, as the crystalline polyester, polyethylene terephthalate, polybutylene terephthalate,
Polyethylene naphthalate and its copolymers and blends are also used. The copolymerization component of the copolymerization polyethylene terephthalate may be an acid component or an alcohol component. Examples of the acid component include aromatic dibasic acids such as isophthalic acid, phthalic acid and naphthalenedicarboxylic acid, aliphatic dicarboxylic acids such as adipic acid, azelaic acid, sebacic acid and decanedicarboxylic acid, and alicyclic compounds such as cyclohexanedicarboxylic acid. Examples thereof include dicarboxylic acids, and examples of alcohol components include aliphatic diols such as butanediol and hexanediol, and alicyclic diols such as cyclohexanedimethanol. These may be used alone or in combination of two or more.

These crystalline polyesters can be used in a single layer or two layers.
It can be used as a multilayer of more than one layer. Of course, the flavor property is greatly affected by the exposure of the steel sheet from the tin-plated layer. As a result of various studies by the present inventors to reduce the amount of iron elution, a squeezed ironing can with a small amount of iron elution is tin-plated steel sheet with tin having a thickness of 0.4 to 6.0 g / m ^2. The surface of the plated steel sheet, which is the inside of the can, has a crystallinity of not more than 5% and a thickness of 15 to 90, which is mainly composed of a crystalline polyester resin.
μm, elongation at break 100% or more, Tg 55 ° C. or more, intrinsic viscosity (hereinafter referred to as IV) 0.65 or more thermoplastic resin coating is arranged, and a cup is made by drawing once or more. , At least 2 mm from the flange end of the can body
It heats up to the part that should be, then redraws if necessary, then irons with a punch and an ironing die with an insertion angle of 2 to 8 degrees, cools immediately after the final ironing process, and The average thickness of the resin layer on the side wall is 5
It was found that it can be obtained by molding to have a thickness of up to 30 μm. The laminate resin layer may be provided on both sides of the tin-plated steel sheet, but the front surface of the can is not directly related to corrosion resistance and flavor resistance, and printing is performed. Therefore, the laminate layer is not always necessary.

The can of the present invention does not require chemical conversion treatment because the resin is laminated on the tin-plated layer on the inner surface. It does not require chemical conversion treatment, improving workability and reducing the amount of water used to 1 /
It can be reduced to 2 to 1/3, and there is an advantage that the burden of wastewater treatment and wastewater treatment waste can be reduced. Although the tin layer is a thin layer of 0.01 μm to 0.25 μm, it exhibits sufficient anticorrosion properties, prevents elution of iron, and exhibits excellent flavor resistance. It is such a thin layer and has an effective coverage of 8
It has hitherto been impossible to form a tin layer of 5% or more.

Since the can body is subjected to large processing, both the plating layer and the resin layer are thinned. The body of the can is greatly affected by the molding process and is likely to cause defects. The laminated thermoplastic resin layer is stretched and oriented, the strength is increased, and the barrier property is improved. The tin temperature during molding is preferably maintained at a temperature not exceeding 232 ° C. This is because tin has a melting point of 231.9 ° C., and therefore, it is effective to maintain the tin film at a temperature at which it does not melt so as to maintain the uniformity of the tin film and prevent a change in the coverage.

A third feature of the present invention is that the forming process is carried out by keeping the temperature of the laminating resin on the punch side below the adhesion temperature in the drawing and ironing process. During molding, the outer surface of the can rises to about 250 ° C., and this heat diffuses to the inner surface of the can, so the temperature of the resin layer also rises. If the temperature rises too much, oriented crystals of the resin layer cannot be obtained and the strength is insufficient, causing molding defects. Further, when the temperature is higher than the adhesion temperature, it adheres to the punch and causes stripping failure after molding.

In order to prevent this, at the same time as cooling the processed portion, the can body is cooled from the outer surface with a coolant immediately after processing,
It is effective to keep the temperature below the sticking temperature. Further, the punch-out property after the final ironing is greatly influenced by the surface condition of the laminate resin. When the resin surface has fine irregularities, minute irregularities on the resin surface are pressed against the punch surface during the ironing process, resulting in a vacuum state, and thus a large force is required to peel from the punch after molding. Therefore, when the cup is stripped out, the edge of the cup is bent, resulting in defective molding. Therefore, in order to improve the punch removal property, the unevenness of the laminate resin surface should be connected in the can height direction so that the air from the cup edge and the punch tip may easily enter the interface between the can wall and the punch. It is effective to insert these to prevent these irregularities from being isolated.

In order to improve the workability, it is preferable that the processing temperature of the laminated resin layer is near Tg. For example P
In the case of ET, good results are obtained when the temperature of the coolant is about 50 ° C. After the cup molding, the laminate resin layer is partially oriented and the moldability is lowered.
It is preferable to raise the temperature to 200 ° C. and perform annealing to remove the strain for good processing.

Since the laminated resin layer is slippery with the punch, it is effective in forming process to lower the entry angle of the ironing die for ironing and increase the surface pressure of the punch. When the coating resin layer slides on the punch, a wavy resin defect occurs. The entering angle of the ironing die is preferably 2 to 8 °, and particularly preferably 6 ° or less. Since the roughness of the metal surface under the laminate layer increases to some extent by the drawing process, resin defects are likely to occur during the drawing process due to the unevenness of the punch surface and the presence of foreign matter. Therefore, it is necessary to make the surface of the punch smooth and to prevent the presence of foreign matter. Further, according to the present invention, since the thermoplastic resin layer mainly composed of polyester coated on the tin-plated steel plate can be drawn and oriented and crystallized in the step of ironing, the corrosion resistance and the flavor resistance are improved.

[0019]

EXAMPLES Next, examples and comparative examples will be specifically described. In Examples and Comparative Examples, drawing and ironing conditions and can making conditions, measurement of coating coefficient of tin coating, measurement of iron-tin alloy coverage, evaluation of flange peeling, evaluation of flavor property, evaluation of actual can storage test were performed. The procedure was as follows.

1. Squeezing and ironing conditions and can-making conditions In Examples 10-1 and Examples 11-1 to 11-4 and Comparative Examples 11-1 to 11-2, examples and comparative examples are as follows. went. Metal plate thickness 0.245
mm single-sided resin-coated steel sheet, with the resin-coated surface facing the inner surface of the can, blanking to a blank diameter of 142 mm, forming a cup with a 1st drawing ratio of 1.6, and then redrawing with a 2nd drawing ratio of 1.3. Then, three-step ironing forming was performed to form a drawn ironing cup having a can body diameter of 65.8 mm, a can body metal thickness of 80 μm, and a neck metal thickness of 135 μm. This squeezing and ironing cup is trimmed to a can height of 123 mm, washed and dried, and then the outer surface is printed and the temperature is set at 200 ° C. for 3 days.
After heating for 0 seconds, the upper part of the can has an inner diameter of 57.25 mm (206 diameter)
The diameter was reduced and the flange was formed and squeezed to obtain an iron can. Molding speed of redrawing and 3 steps of ironing is 200
It is cpm. In Example 10-1, the drawing and ironing conditions are different from the above, but the neck and flange conditions are the same. Examples 11-1 to 11-4, Comparative Examples 11-1 to 11-2
The drawing and ironing conditions are the same as above, but the neck and flange conditions are different from the above. Only the points that differ between the individual examples and comparative examples will be clearly indicated.

2. Cup heating conditions The first diaphragm cup is placed upright and a high frequency coil is installed above the cup so that high frequency magnetic flux is applied to the cup edge. The high frequency coil was installed at a position 3 mm from the cup edge. The high frequency output was adjusted to control the temperature of the cup edge. The temperature of the cup edge was evaluated by discoloring by applying several kinds of temperature-indicating paint to the resin surface on the inner surface of the cup. Unless otherwise noted, the conditions in Examples and Comparative Examples were a treatment time of 1.0 second, and the ultimate temperature of the cup edge at this time was about 300 ° C.

3. Measuring the coating coefficient of tin coating After removing the resin coating on the inner surface of the can wall, including the neck and flange parts, divide the side wall of the inner surface of the can into circumferential lengths of 2.0 mm 1
EPMA line analysis of tin is performed under the following conditions at 0 locations, and the coverage factor of the tin coating is determined for each location by the following formula. The value of the smallest part of the coating coefficient of the tin coating at each location thus obtained is taken as the coating coefficient of the tin coating of this can. Measurement method: WDS, detection crystal: PET, accelerating voltage: 10k
v, sample current: 1 × 10E-8A, beam diameter 1.0 μ
m, detected X-ray: SnLα ray, time constant: 1.
0 (s), scanning speed: 50 μm / min. Tin film coating coefficient (%) = (length of the tin content of 0.1 g / m ² or more (mm)) × 100 / 2.0 (mm)

4. Measurement of Iron-Tin Alloy Coverage A crystalline polyester resin from the flange of the can to the neck portion of, for example, 1,1,1,3,3,3-hexafluoro-
Dissolve in a solvent such as 2-propanol, cut off up to 2 mm from the tip of the flange, seal the flange edge and cut surface with resin, and regarding the metal surface that was in contact with the thermoplastic resin, JIS G 3303 "tin tin The amount of alloy tin (A) and the amount of surface tin (B) are measured by a method according to the “adhesion amount test method, electrolytic stripping method”. At this time, the current density is 10
Performed at mA / cm ² . The iron-tin alloy coverage (C) is defined by the following formula. C = A / (A + B) Further, when the metal surface after melting the thermoplastic resin is magnified 5000 times or more with a scanning electron microscope, columnar or granular iron-tin alloy is observed, and smooth metal tin. They are clearly different from faces and can be identified.

5. Flange peeling evaluation method After necking up to a diameter of 206 or 202 and further flanging, the degree of peeling of the flange is 100.
0 cans were inspected, and when there was peeling, it was evaluated as x, and the number of peeled cans was evaluated. The standard of the peeling of the flange portion was x when there was peeling of 0.5 mm or more from the flange edge in any portion of the can circumference. Alternatively, the case where there was one or more linear peels in the can height direction was marked with X, and the case where there was no peeling was marked with O.

6. Evaluation of flavor property When the aroma component of the content is sorbed on the inner surface material of the can, the flavor of the content changes. In addition, the flavor of the contents changes even if the material on the inner surface of the can dissolves into the contents. The flavor retention was evaluated by the sensory test of the content flavor in the actual can storage test and the aroma component sorption rate. In the content flavor sensory test, after filling with Coca Cola Light (carbonated beverage manufactured by Japan Coca-Cola Co., Ltd.), the contents were stored at room temperature for 3 months, and the sensory superiority difference from the liquid without storage over time was examined.
When the risk rate was 5%, there was no significant difference, and when there was a risk rate of 5%, there was a significant difference. The fragrance component sorption rate was measured by the Japan Food Industry Society Vol. 34, No. 5,1987,2
It was performed according to the method described in 67-273. That is, as a model liquid, a model solution (1% citric acid) to which a citrus flavor (myrcene, α-terpinene, d-limonene, γ-terpinene, p-cymene, and 2 curene were mixed so as to be 10 ppm each) was added to a test can. After filling, winding and storing at 20 ° C for 10 days, the aroma components are collected and concentrated from the film on the inner surface of the can, and gas chromatographic analysis is performed.
The distribution ratio from the pre-filling solution (amount in inner film / amount in content liquid) was determined. The methods for collecting, concentrating, and analyzing the aroma components were in accordance with the above-mentioned document. A distribution ratio of d-limonene of less than 2% was evaluated as ◯, and a distribution ratio of 2% or more was evaluated as x.

7. Evaluation of actual can storage test 100 cans were filled with Coca-Collite (carbonated drink) by a standard method, the lid was closed, and the product was stored at 37 ° C for 6 months and then opened, and the can inner surface was corroded under film. (Hereinafter UFC
(Abbreviated as)), and the iron ions eluted in the contents were measured by atomic absorption spectrometry, and the average amount of elution was calculated. UFC has a UFC area of 0-10
mm ² was evaluated as ◯, and those exceeding 10 mm ² were evaluated as x.

8. Measurement of Crystallinity of Crystalline Polyester Resin The crystallinity of the crystalline polyester resin that is the laminated resin layer is measured by SEN-IGAKKAISHI, Vo.
l. 33, No. 10 (1977), 780-788. That is, the X-ray diffraction scattering intensity distribution was separated into contributions from the crystalline and amorphous phases, and calculated as an integrated intensity ratio with respect to the Bragg angle.

9. Tg of resin before processing, elongation at break (hereinafter E
(notated as 1), and measurement of IV After peeling the resin layer of the laminate plate from the metal plate, Tg and EL (stretch) were measured by a conventional method. IV was measured in o-chlorophenol at 25 ° C.

10. Measurement of the average tin coating thickness on the inside of the can wall and the average organic resin coating on the inside of the can wall The average tin coating thickness on the inside of the can wall is the maximum peeling of the organic resin on the inside of the can wall (30-80 mm from the can bottom). After that, make 3 circular materials of 20mmφ and make fluorescent X
The measurement values obtained by the linear method were arithmetically averaged. The average thickness of the organic resin film on the inner surface of the can wall was obtained by arithmetically averaging the measured values obtained by dissolving the metal at the same site, peeling off the organic resin, and measuring at arbitrary 10 points with a micrometer.

EXAMPLE 1-1 A 90 μm thick amorphous crystalline polyester resin (polyethylene terephthalate / isophthalate system) was heat-treated on one side of 0.245 mm thick, temper 4, E2.8 / 2.8 tinplate. Coated and quenched. T after coating with this resin
Table 1 shows g, EL, IV and crystallinity. Using this one-sided resin-coated tin-plated steel sheet, a drawn and ironed can was produced under the conditions shown in Table 1. The conditions and evaluation are shown in Table 1.

Examples 1-2 and 1-3, Comparative examples 1-1 and 1
-2 In Examples 1-2 and 1-3 and Comparative Example 1-1, the thickness of the organic resin film coated on the tin-plated steel sheet is 30 μm and 15 respectively.
A squeezed ironing can was produced in the same manner as in Example 1-1 except that the thickness was 9 μm and 9 μm. In Comparative Example 1-2, a drawn and ironed can was produced in the same manner as in Example 1-1, except that the thickness of the organic resin film coated on the tin-plated steel sheet was 120 μm. The conditions and evaluation are shown in Table 1. Flange and actual cans were not evaluated because the flange part peeled off during flange molding.

Example 2-1 A biaxially stretched crystalline polyester resin (polyethylene terephthalate / isophthalate system) having a thickness of 30 μm is provided on one side of 0.245 mm thick, temper 4, E2.8 / 2.8 tinplate. Heat coated, 230 ° C so that the crystallinity of the polyester resin on the laminate (before molding) becomes 2%.
After adjusting the holding time at, it was quenched. Table 1 shows Tg, EL, IV and crystallinity after coating with this resin. Using this single-sided resin-coated tin-plated steel sheet, a drawn and ironed can was produced. The conditions and evaluation are shown in Table 1.

Example 2-2, Comparative Examples 2-1 and 2-2 In Example 2-2 and Comparative Examples 2-1, 2-2, the crystallinity of the polyester resin of the laminate plate (before molding) is respectively. 5
%, 9%, and 24%, and a squeezed ironing can was produced in the same manner as in Example 2-1. The conditions and evaluation are shown in Table 1.

Example 3-1 A crystalline polyester resin (polyethylene terephthalate / isophthalate system) in an amorphous state having a thickness of 30 μm was heated on one side of 0.245 mm thick, temper 4, E2.8 / 2.8 tinplate. Coated and quenched. At this time, the Tg was set to 64 ° C. by changing the copolymerization ratio of isophthalic acid, and an ironing can was manufactured using this steel sheet. The conditions and evaluation are shown in Table 1.

Example 3-2, Comparative Examples 3-1, 3-2 In Example 3-2, Comparative Examples 3-1, 3-2, the Tg of the polyester resin was 58 ° C. (isophthalic acid copolymerization),
A squeezed ironing can was produced in the same manner as in Example 3-1 except that the temperatures were 54 ° C. (sebacic acid copolymerization) and 48 ° C. (adipic acid copolymerization). The conditions and evaluation are shown in Table 1. Comparative Example 3
For -3, one side (inner side) of the tin-plated steel sheet was coated with a thermosetting resin having a thickness of 3 μm, and then dried and baked (semi-cured state),
A squeezed ironing can was manufactured in the same manner as in Example 3-1 except that a crystalline polyester resin in an amorphous state having a thickness of 30 μm was thermally coated thereon and quenched. The conditions and evaluation are shown in Table 1. In Comparative Example 3-4, a squeezed ironing can was manufactured in the same manner as in Example 3-1 except that the resin to be thermally coated was a polyester resin (polyethylene terephthalate / isophthalate system) having no thermal crystallinity. The conditions and evaluation are shown in Table 1.

Example 4-1 An amorphous crystalline polyester resin (polyethylene terephthalate / isophthalate type) having a thickness of 30 μm was heated on one side of 0.245 mm thick, temper 4, E2.8 / 2.8 tin plate. Coated and quenched. This resin was made to have a breaking elongation of 285% by changing the copolymerization ratio. Using this single-sided resin-coated tin-plated steel sheet, a drawn and ironed can was produced. The conditions and evaluation are shown in Table 1.

Example 4-2, Comparative Example 4-1 Example 4-2 and Comparative Example 4-1 were the same as Example 4-1 except that the breaking elongation of the polyester resin was 133% and 3%, respectively. A squeezed ironing can was produced in the same manner. The conditions and evaluation are shown in Table 1.

Example 5-1 Biaxially stretched crystalline polyester resin (polyethylene) having a thickness of 30 μm and an IV of about 1.0 on one side of 0.245 mm thick, temper 4, E2.8 / 2.8 tinplate. A terephthalate / isophthalate system) was heat-coated, and the laminated plate (before molding) was kept at 230 ° C. so that the crystallinity of the polyester resin was 5%, followed by rapid cooling. Using this single-sided resin-coated tin-plated steel sheet, a drawn and ironed can was produced. The conditions and evaluation are shown in Table 1.

Example 5-2, Comparative Examples 5-1 and 5-2 In Example 5-2 and Comparative Examples 5-1 and 5-2, the IV of the polyester resin after lamination was 0.68, 0. 6
A drawn and ironed can was produced in the same manner as in Example 5-1 except that the values were 3, 0.56. The conditions and evaluation are shown in Table 1.

[0040]

[Table 1]

(Note) A to S in the table are abbreviations having the following meanings. A: Isophthalic acid copolymerized PET B: Sebacic acid copolymerized PET C: Adipic acid copolymerized PET D: Thermosetting resin (adhesive layer) + isophthalic acid copolymerized PE
T E: isophthalic acid copolymerized PET having no thermal crystallinity F: can inner surface average organic resin coating (μm) G: can inner surface average tin coating thickness (g / m ² ) H: can inner surface tin effective coverage (0.1 g / Proportion of m ² or more) J: Tg (° C.) of resin before processing K: IV (dl / g) of resin before processing L: EL (%) of resin before processing M: Crystallinity of resin before processing (%) N: Cooling just before final ironing O: Ironing die entry angle (degrees) P: Corrosion evaluation Q: Flavor evaluation R: Aroma component sorption S: Flavor sensory test UFC: Submembrane corrosion Diameter: After neck Nominal diameter designation rate: Iron-tin alloy coating rate Evaluation: Flange peeling evaluation In Comparative Example 1-2, the flange was peeled off due to poor molding and can making conditions. In addition, punchability was poor and continuous molding was impossible.

Comparative Examples 6-1 and 6-2 Comparative Examples 6-1 and 6-2 are 0.245 mm thick, temper 4, D6.0 / 2.8 tint, E2.8 / 2.8 tint. With the 2.8 side as the outer surface, squeeze and squeeze without an organic resin coating, wash and dry, then spray-paint a vinyl organosol-based resin, bake cure, and squeeze ironing can Cans were made, the average tin coating thickness on the inside of the can wall was measured, the coating coefficient of the tin coating was measured, and the flange peeling was evaluated.
The flavor property was evaluated and the actual can storage test was evaluated. Iron-
The tin alloy coverage was not measured. As a result, the average tin coating thickness on the inner surface of the can wall was 2.0 g / m ² and 0.9, respectively.
g / m ² , tin coverage on the inner surface of the can wall is 81%,
77%, the number of peeled cans on the flange was 0, and the Fe elution amounts in the actual can storage test were 2.7 ppm and 6.5, respectively.
ppm, the UFC rating was x, x, and the flavor sensory test rating was x, x, respectively. Further, in the actual can storage test, 5 out of 100 cans and 9 cans were leaked by perforations from the lid-wound portion.

Example 7-1 A crystalline polyester resin (polyethylene) having a thickness of 30 μm in an amorphous state was formed on the 6.0 side (inner side) of a tin plate having a thickness of 0.245 mm, temper 4 and D6.0 / 2.8. (Terephthalate / isophthalate system) was heat coated and quenched. Using this single-sided resin-coated tin-plated steel sheet, a drawn and ironed can was produced. The conditions and evaluation are shown in Table 2.

Examples 7-2 and 7-3, Comparative Examples 7-1 and 7
-2 Example 7-2 is D4.5 / 2.8 tint (4.5 is the inner surface side), and Example 7-3 and Comparative Examples 7-1 and 7-2 are mild steel plate one surface (inner surface side). The tin plating amount of each is 0.6 g /
m ^2, subjected to tin plating so tin plating amount of 0.3 g ^/ m 2, the other surface was 0.0 g / ^{m 2} (outer surface side) is 2.8 Both, the embodiment otherwise Example 7 A squeezed ironing can was produced in the same manner as in 1. The conditions and evaluation are shown in Table 2.

Comparative Example 8 In Comparative Example 8, a squeezed ironing can was produced in the same manner as in Example 1-2 except that cooling was not performed after the final ironing. The punch did not come out well after the ironing and the molding cup could not be obtained.

Example 9-1 A squeezed and ironed can was produced in the same manner as in Example 1-2 except that the 1st, 2nd, and 3rd all had an inning angle of 2 °. The conditions and evaluation are shown in Table 2.

Examples 9-2 and 9-3, Comparative Examples 9-1 and 9
-2 Examples 9-2, 9-3, Comparative Examples 9-1, 9-2 are ID
A squeezed ironing can was produced in the same manner as in Example 9-1 except that the entry angles were 6 °, 8 °, 10 °, and 12 °, respectively. The conditions and evaluation are shown in Table 2.

Example 10-1 A crystalline polyester resin (polyethylene terephthalate / isophthalate system) having a thickness of 30 μm in an amorphous state was heated on one side of 0.245 mm thick, temper 1, E2.8 / 2.8 tinplate. Coated and quenched. T after coating with this resin
Table 1 shows g, El, IV and crystallinity. Using this single-sided resin-coated tin-plated steel sheet, the resin-coated surface is the inner surface of the can, blanking to a blank diameter of 142 mm, forming a cup with a drawing ratio of 2.1, and then performing three-step ironing forming A drawn and ironed cup having a body diameter of 65.8 mm, a can body metal thickness of 80 μm, and a neck portion metal thickness of 135 μm was formed. At this time, the cup edge of the first squeezing cup was heat-treated at a high frequency. This squeezed ironing cup has a can height of 12
After trimming to 3 mm, washing and drying, the outer surface is printed and heated at 200 ° C for 30 seconds, then the top of the can has an inner diameter of 5
While reducing the diameter to 7.25 mm, a flange was formed and drawn to obtain an iron can. Table 2 shows the molding conditions. With respect to the drawn and ironed can thus obtained, the average tin coating thickness, the organic resin coating thickness, the measurement of the coating coefficient of the tin coating, the measurement of the iron-tin alloy coverage, the visual observation of the canned state, and the evaluation of the flavor property Then, the storage test of real cans was evaluated. The results are shown in Table 2.

Example 11-1 The first squeezing cup was subjected to high-frequency heat treatment for 1.0 second at a temperature reaching the cup edge of about 300 ° C., and the upper part of the can had an inner diameter of 5
An squeezed iron can was prepared in the same manner as in Example 1-2 except that the diameter was reduced to 2.40 mm (202 diameter). The conditions and evaluation results are shown in Table 2.

Example 11-2 Example 11-2, except that the first squeezing cup was subjected to high-frequency heat treatment for 1.0 second at a temperature reaching the cup edge of about 320 ° C.
A squeezed ironing can was prepared in the same manner as in -1. The conditions and evaluation results are shown in Table 2.

Example 11-3 The tin plating amount of the tin plate on the inner surface of the can was 6.0 g / m.
^A squeezed ironed can was prepared in the same manner as in Example 11-1 except that the number was ² . The conditions and evaluation results are shown in Table 2.

Example 11-4 The tin plating amount of tinplate on the inner surface of a can was 0.6 g / m.
^A squeezed ironed can was prepared in the same manner as in Example 11-1 except that the number was ² . The conditions and evaluation results are shown in Table 2.

Comparative Example 11-1 Example 11 was repeated, except that the first squeezing cup was subjected to high-frequency heat treatment for 1.0 second at the temperature reached to the cup edge of about 240 ° C.
A squeezed ironing can was prepared in the same manner as in -1. The conditions and evaluation results are shown in Table 2.

Comparative Example 11-2 Example 11-1 except that there is no heat treatment in the cup.
Squeezing and ironing cans were made in the same manner as. The conditions and evaluation results are shown in Table 2.

Examples 1-1 to 1-3, 3-1, 3-2,
From 7-1 to 7-3, 10-1, 11-1 to 11-4,
The squeezed and ironed can is formed from a tin-plated steel sheet on which the inner surface of the can is previously coated with a thermoplastic resin.The main component of the thermoplastic resin on the inner surface of the can is crystalline polyester resin. The average thickness of the plastic resin layer is 5 to
The average tin coating thickness on the inner surface of the can wall is 0.2 to 30 μm.
2.0 g / m ² , the effective coverage of tin is 85% or more, and at least 2 mm from the flange tip, the metal surface in contact with the thermoplastic resin is coated with the iron-tin alloy. When the coverage of the iron-tin alloy is 0.7 or more, it can be seen that the corrosion resistance (Fe elution, UFC, perforation corrosion resistance) and flavor (fragrance component sorption resistance, offensive odor component elution resistance) are excellent. .

From Comparative Examples 6-1 and 6-2, when the drawn and ironed can was formed from a tin-plated steel sheet without an organic coating and then spray-painted to form an organic coating, the effective tin coverage was Is less than 85%, which means that the corrosion resistance and flavor are inferior.

From Comparative Example 3-3, when the drawn and ironed can is formed from a tin-plated steel sheet whose inner surface is coated with a thermosetting resin in advance, and a thermoplastic resin is coated thereon, the effectiveness of tin is improved. It can be seen that the coverage is less than 85% and the corrosion resistance and flavor are inferior.

From Comparative Example 3-4, when the main component of the thermoplastic resin on the inner surface of the can body is an amorphous (non-thermocrystalline) polyester resin, the effective tin coverage is less than 85%, and the corrosion resistance and flavor are reduced. It turns out that the sex is inferior.

From Comparative Example 1-1, it can be seen that when the average thickness of the thermoplastic resin on the side wall of the can is less than 5 μm, the effective coverage of tin is less than 85%, and the corrosion resistance and flavor are inferior.

From Comparative Example 1-2, it can be seen that when the average thickness of the thermoplastic resin on the side wall of the can exceeds 30 μm, peeling occurs between the organic resin and the metal on the flange and the can cannot be manufactured.

From Comparative Examples 7-1 and 7-2, when the average tin coating thickness on the inner surface of the can wall is less than 0.2 g / m ² , the effective tin coverage is less than 85% and the corrosion resistance and flavor are poor. I understand.

Comparative Examples 1-1, 2-1, 2-2, 3-1 to
3-4, 4-1, 5-1, 5-2, 6-1, 6-2, 7
From -1, 7-2, 9-1, 9-2, 11-1, 11-2, it is understood that when the effective coverage of tin is less than 85%, the corrosion resistance and the flavor property are inferior. From Comparative Example 11-1, it can be seen that when the high-frequency treatment temperature of the cup edge is low, the coverage of the iron-tin alloy is less than 0.7, flange peeling occurs, and a can that is worthy of being subjected to the pack test cannot be manufactured.
From Comparative Example 11-2, when there is no heat treatment in the cup,
It can be seen that the iron-tin alloy coverage is less than 0.7, resulting in flange peeling, and a can worthy of the pack test cannot be manufactured. From Comparative Examples 11-1 and 11-2, when the coverage of the iron-tin alloy is less than 0.7, flange peeling occurs,
You can see that it cannot be made.

From Comparative Example 8, it can be seen that if cooling is not carried out after the final ironing, punchability is poor and continuous molding cannot be performed.

Examples 2-1, 2-2, 3-1, 3-2,
4-1, 4-2, 5-1, 5-2, 9-1 to 9-3, 1
1-1 to 11-4, Comparative Examples 2-1, 2-2, 3-1, 3
-2, 4-1, 5-1, 5-2, 8, 9-1, 9-2,
From 11-1 and 11-2, the Tg of the crystalline polyester resin which is the main component of the thermoplastic resin on the inner surface of the can body is 55 ° C. or higher, the IV is 0.65 or higher, and the crystallinity of the resin before molding is 5 % Or less, El is 100% or more, a cup is made by drawing once or more, and heat treatment is performed up to a portion that should be at least 2 mm from the flange tip of the can body, and then redrawing is performed if necessary. A tinned steel sheet having an ironing die with an entering angle of 2 to 8 degrees and having been cooled and manufactured immediately after the final ironing step, so that the surface of the drawn and ironed can becomes the inner surface of the can with a thermoplastic resin pre-heat coated. , The main component of the thermoplastic resin on the inner surface of the can body is a crystalline polyester resin, the average thickness of the thermoplastic resin layer on the side wall of the can is 5 to 30 μm, and the average tin coating thickness on the inner surface of the can wall is 0.2 It was 2.0 g / m ^2, the effective coverage of the tin is not more than 85%, of the total circumference of at least 2mm from the flange tip metal surface in contact with the thermoplastic resin iron - is coated with a tin alloy It can be seen that a squeezed ironing can having excellent corrosion resistance and flavor is manufactured.

[0065]

[Table 2]

(Note) A to S in the table are abbreviations having the following meanings. A: Isophthalic acid copolymerized PET B: Sebacic acid copolymerized PET C: Adipic acid copolymerized PET D: Thermosetting resin (adhesive layer) + isophthalic acid copolymerized PE
T E: isophthalic acid copolymerized PET having no thermal crystallinity F: can inner surface average organic resin coating (μm) G: can inner surface average tin coating thickness (g / m ² ) H: can inner surface tin effective coverage (0.1 g / Proportion of m ² or more) J: Tg (° C.) of resin before processing K: IV (dl / g) of resin before processing L: EL (%) of resin before processing M: Crystallinity of resin before processing (%) N: Cooling just before final ironing O: Ironing die entry angle (degrees) P: Corrosion evaluation Q: Flavor evaluation R: Aroma component sorption S: Flavor sensory test UFC: Submembrane corrosion Diameter: After neck Nominal diameter designation rate: Iron-tin alloy coating rate Evaluation: Flange peeling evaluation In Comparative Examples 11-1 and 11-2, the molded and canned state was poor and the flange peeled. In Comparative Example 8, the neck flange portion was peeled off. Punch removal was poor and continuous molding was impossible.

[0067]

According to the present invention is not known in the prior art, the tin-plating layer is a thin layer of ^{0.2g / m 2 ~2.0g / m 2} ,
Provided on the surface thereof is a laminated layer of thermoplastic resin having a thickness of 5 to 30 μm. The effective coverage of tin is 85% or more, and the thermoplastic resin is in contact with the entire circumference of at least 2 mm from the flange tip. The metal surface is coated with an iron-tin alloy, and the iron-tin alloy has a coating ratio of 0.7 or more, and is a drawn and ironed can, which is very effective in corrosion resistance and flavor resistance.

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] September 29, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0021

[Correction method] Change

[Correction content]

2. Cup heating conditions Place the first squeezing cup upright and place a high frequency induction above the cup.
Install a heating coil so that high-frequency magnetic flux is applied to the cup edge. The high frequency induction heating coil was installed at a position 3 mm from the cup edge. The high frequency output was adjusted to control the temperature of the cup edge. The temperature of the cup edge was evaluated by discoloring by applying several kinds of temperature-indicating paint to the resin surface on the inner surface of the cup. The conditions in Examples and Comparative Examples are
Unless otherwise noted, the processing time was 1.0 second, and the temperature reached by the cup edge at this time was about 300 ° C.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0048

[Correction method] Change

[Correction content]

Example 10-1 A crystalline polyester resin (polyethylene terephthalate / isophthalate system) having a thickness of 30 μm in an amorphous state was heated on one side of 0.245 mm thick, temper 1, E2.8 / 2.8 tinplate. Coated and quenched. T after coating with this resin
Table 1 shows g, El, IV and crystallinity. Using this single-sided resin-coated tin-plated steel sheet, the resin-coated surface is the inner surface of the can, blanking to a blank diameter of 142 mm, forming a cup with a drawing ratio of 2.1, and then performing three-step ironing forming A drawn and ironed cup having a body diameter of 65.8 mm, a can body metal thickness of 80 μm, and a neck portion metal thickness of 135 μm was formed. At this time, the cup edge of the first squeeze cup is induced by high frequency.
Conducted heat treatment. This squeezed ironing cup has a can height of 1
After trimming to 23 mm, washing and drying,
After printing the outer surface and heating at 200 ℃ for 30 seconds, the top of the can has an inner diameter of 5
While reducing the diameter to 7.25 mm, a flange was formed and drawn to obtain an iron can. Table 2 shows the molding conditions. With respect to the drawn and ironed can thus obtained, the average tin coating thickness, the organic resin coating thickness, the measurement of the coating coefficient of the tin coating, the measurement of the iron-tin alloy coverage, the visual observation of the canned state, and the evaluation of the flavor property Then, the storage test of real cans was evaluated. The results are shown in Table 2.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0049

[Correction method] Change

[Correction content]

Example 11-1 The first squeezing cup was subjected to high-frequency induction heating at a temperature reaching the cup edge of about 300 ° C. for 1.0 second, and the upper part of the can was reduced in diameter to 52.40 mm (202 diameter). Except for this, a squeezed ironed can was prepared in the same manner as in Example 1-2. The conditions and evaluation results are shown in Table 2.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0050

[Correction method] Change

[Correction content]

Example 11-2 A squeezed and ironed can was prepared in the same manner as in Example 11-1 except that the first squeezing cup was subjected to high-frequency induction heating treatment at the cup edge reaching temperature of about 320 ° C. for 1.0 second. . The conditions and evaluation results are shown in Table 2.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0053

[Correction method] Change

[Correction content]

Comparative Example 11-1 A squeezed and ironed can was prepared in the same manner as in Example 11-1 except that the first squeezing cup was subjected to the high frequency induction heating treatment at the cup edge reaching temperature of about 240 ° C. for 1.0 second. . The conditions and evaluation results are shown in Table 2.

[Procedure correction 6]

[Document name to be amended] Statement

[Correction target item name] 0062

[Correction method] Change

[Correction content]

Comparative Examples 1-1, 2-1, 2-2, 3-1 to
3-4, 4-1, 5-1, 5-2, 6-1, 6-2, 7
From -1, 7-2, 9-1, 9-2, 11-1, 11-2, it is understood that when the effective coverage of tin is less than 85%, the corrosion resistance and the flavor property are inferior. From Comparative Example 11-1, when the high-frequency induction heat treatment temperature of the cup edge is low, iron-
It can be seen that the tin alloy coverage is less than 0.7, resulting in flaking of the flange, and a can worthy of the pack test cannot be manufactured. From Comparative Example 11-2, it can be seen that, without heat treatment in the cup, the iron-tin alloy coverage was less than 0.7, resulting in flange peeling, and a can worthy of the pack test cannot be manufactured. From Comparative Examples 11-1 and 11-2,
It can be seen that if the iron-tin alloy coverage is less than 0.7, flange peeling occurs and the can cannot be manufactured.

Claims (7)

[Claims] 1. A drawn and ironed can formed by using a tin-plated steel sheet coated with a thermoplastic resin in advance on at least one inner surface of the can, wherein the main component of the thermoplastic resin is a crystalline polyester resin, and the resin on the side wall of the can is used. The layer has an average thickness of 5 to 30 μm, and the tin coating has an average thickness of 0.2 to 2.
It is 0 g / m ² , the effective coverage of tin is 85% or more, and the metal surface in contact with the thermoplastic resin at least 2 mm from the flange tip is in contact with the iron-tin alloy. A two-piece squeezed ironing can with excellent corrosion resistance and flavor, characterized by a tin alloy coverage of 0.7 or more. 2. The crystalline polyester resin, which is the main component of the coating resin, has a Tg of 55 ° C. or higher and an intrinsic viscosity (IV) of 0.
A two-piece squeezed ironing can having a corrosion resistance and a flavor property according to claim 1, which is 65 or more. 3. The effective coverage of tin is 0.
The two-piece squeezed and ironed can having excellent corrosion resistance and flavor properties according to claim 1 or 2, which is a value indicating the proportion occupied by a portion of 1 g / m ² or more. 4. From the amount of alloy tin A and the amount of surface tin B from the flange tip to 2 mm, the coating ratio of iron-tin alloy is C = A /
A two-piece squeezed and ironed can having excellent corrosion resistance and flavor properties according to any one of claims 1 to 3, which has a value C determined by the formula (A + B). 5. The tin plating thickness is 0.4 to 6.0 g / m ^2.
On the surface of the tin-plated steel sheet that is the inside of the can, the crystallinity of the crystalline polyester resin is 5% or less, the thickness is 15 to 90 μm, the elongation at break is 100% or more, and the Tg is 55.
A thermoplastic resin coating with an intrinsic viscosity (IV) of 0.65 or more is placed, and a cup is made by drawing once or more, and the portion from the tip of the flange of the can to at least 2 mm is heated. The resin layer on the side wall of the can can be treated and then redrawn if necessary, and then ironed by a punch and an ironing die with an insertion angle of 2 to 8 degrees, and immediately cooled after the final ironing step. Has an average thickness of 5 to 30 μm, and the tin coating has an average thickness of 0.2 to
2.0 g / m ² , the effective coverage ratio of tin is 85% or more, and the metal surface in contact with the thermoplastic resin of at least 2 mm from the flange tip is covered with the iron-tin alloy. A method for producing a two-piece squeezed ironing can having a tin alloy coverage of 0.7 or more and excellent corrosion resistance and flavor. 6. The temperature of the tin layer on the inner surface of the cup is set to 23 during molding.
The corrosion resistance and the flavor property according to claim 5, wherein the temperature is maintained at a temperature not exceeding 2 ° C, the final ironing is followed by rapid cooling to reduce the tin temperature on the inner surface side of the necking portion and the flange portion to 232 ° C or less. An excellent method of manufacturing a two-piece squeezed ironing can. 7. A two-piece squeezed and ironed can excellent in corrosion resistance and flavor according to claim 5 or 6, wherein the thermoplastic resin coating containing a polyester resin as a main component is squeezed and oriented and crystallized in the step of ironing. Production method.