JPH07258794A - Resin coated steel plate for dry drawing and ironing cans - Google Patents

Abstract

(57) [Summary] [Purpose] Water cooling of a thin-piece can with a can height as high as twice the can diameter and a can wall thickness as thin as 70-40% of the original plate thickness. Provided is a double-sided organic resin-coated steel sheet which can be formed by a dry method under a specific condition without using a lubricant by a thickness reduction processing method. [Structure] Crystal grain size is 6 ~ 30μm, yield strength is 25 ~ 7
0 kg / mm ² , center line average roughness 0.05-0.6 μm, aging index 5 kg / mm ² or less, plate thickness 0.15 to 0.30 mm, both sides of electrolytic chromic acid treated steel plate A resin-coated steel sheet for dry drawing and ironing cans, which has a thermoplastic resin film coated on the top and a high-temperature volatile lubricant applied to the top surface.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to materials for two-piece cans produced by processes including ironing. In detail, it is not necessary to wash the can after making it without cooling or lubricating it with water or a water-based lubricant.
TECHNICAL FIELD The present invention relates to a thermoplastic resin-coated steel sheet suitable for producing a two-piece can having a thin can wall by a process including an ironing process.

[0002]

2. Description of the Related Art Conventionally, as a two-piece can in which a can body and a can bottom are integrated, a DRD made of a tin plate, an aluminum plate, an aluminum alloy plate, an electrolytic chromic acid treated steel plate, etc.
Can (Draw and Redrow Can),
DI cans (Draw and Ironed Can) are common, and in recent years, DTR cans (Draw-Thin /
Redraw Can) has also been put to practical use. Since the DRD can is manufactured by drawing and redrawing, the can wall thickness increases in proportion to the can height. Therefore, from the viewpoint of economy, it is generally applied to a can having a low height, and an electrolytic chromic acid-treated steel plate, a tin plate, or an aluminum alloy plate is used as a base metal plate. On the other hand, the DI can manufactured by drawing and ironing can be economically applied to cans with a high can height because the can wall thickness can be about 1/3 of the original plate thickness. Tin plate and aluminum alloy plate are used. Further, the DRD can and the DI can are different from each other in that the DRD can is drawn on a metal plate previously coated with an organic film, whereas the DI can is painted after ironing. This is because the degree of processing and the stress state during processing are greatly different between DRD processing and DI processing. When a metal plate coated with an organic film is applied to DI processing, which has a very high degree of processing and surface pressure on the can wall, it is practically used due to seizure of the organic film on the mold and damage to the organic film on the inner and outer surfaces. It has not been realized.

On the other hand, a DTR can is manufactured by reducing the shoulder radius at the time of redrawing, and bending the shoulder, and returning the bend while applying a large pulling force to the can wall. DTR cans are manufactured by a process that closely resembles drawing, but because the can wall is stretched,
The can wall will be slightly thinner than the original plate thickness. Also, unlike ironing, a large surface pressure is not applied to the can wall between the die and the punch, so the load on the organic film is not so large, the organic film is less likely to be damaged, and the organic film coating metal A plate can be applied, and currently, an electrolytic chromic acid-treated steel plate coated with a thermoplastic resin is industrially used. However, in the case of a DTR can, because the processing is mainly based on the pulling force, the can wall is likely to break during processing,
The can wall thickness is about 80% of the original plate thickness, which is thicker than that of the DI can.

As described above, the DRD can, the DI can, the DTR can, and the manufacturing method thereof have respective advantages and disadvantages. Here, in the present invention, the can height is as high as twice the can diameter like a DI can, and the can wall thickness is 70% of the original plate thickness.
It is to provide a steel sheet coated with a thermoplastic resin on both sides, which is suitable for obtaining a can as thin as about -40%, and the point that the present invention is particularly important is in the process of manufacturing such a can. It is an object of the present invention to provide a thermoplastic resin-coated steel sheet capable of omitting the use of an emulsion system, a water-soluble lubricant, etc. currently used for cooling and lubrication in the manufacture of DI cans. By using a steel sheet laminated with a thermoplastic resin in advance, it is possible to prevent coating baking in the can manufacturing process and prevent the scattering of the solvent.Furthermore, by using no coolant or lubricant, subsequent cleaning, Drying and waste liquid treatment can be omitted. That is, a thermoplastic resin metal plate capable of producing a can having a high can height and a thin can wall thickness, which does not require such water-based cooling and a lubricant, and does not require cleaning of the can after the can is manufactured. I can't find any disclosures relating to such cans and, of course, such disclosures. Although not intended to have the same purpose as the present invention, there are the following relevant ones.

Japanese Unexamined Patent Publication (Kokai) No. 62-275172 relates to an organic resin-coated metal plate for a two-piece can. It is intended to enhance the retention of the coolant (water-based cooling, lubricant) on the outer surface side, which is severely processed during ironing. It is one of the challenges. That is, it is premised on the use of water-based cooling and a lubricant, which is largely different from the object of the present invention. In addition, Japanese Patent Publication No. 501501638 also processes a metal can by laminating a polyester resin film on one or both sides of the metal sheet into a DI can. Although the subsequent can cleaning process has been simplified, the use of a lubricant that requires cleaning of the can after manufacturing is required in the drawing process, and cleaning of the can after manufacturing is completely eliminated. Not considered. Further, JP-A-4-91825 discloses that a can wall is thinned by bending and unbending a thermoplastic resin-coated metal plate without water-based cooling and using a lubricant, that is, using a high-temperature volatile lubricant as a lubricant. However, as shown in the examples, the degree of thinning is about 20%, which is smaller than the target value of the present invention.

[0006]

According to the present invention, the can height is as high as twice the can diameter, and the can wall thickness is 70% of the original plate thickness.
Water-cooling a thin two-piece can with a thickness of about 40%
An object of the present invention is to provide a thermoplastic resin-coated steel sheet that can be formed without using a lubricant (hereinafter referred to as a dry type) and does not require cleaning of a can after it is manufactured. By reducing the thickness of the can wall to a thickness of 70 to 40% of the original plate thickness, the can height increases in proportion to the degree of thinning. Although this point meets the purpose of the present invention, as the degree of thinning increases, the adhesion between the outer surface of the can wall and the mold, damage to the surface resin layer, and breakage of the can wall are more likely to occur. In particular, in the present invention, which is characterized in that water-based cooling and no lubricant are used, damage to the resin layer on the outer surface of the can and breakage of the can wall due to the damage are likely to occur, and prevention of these is the greatest problem. . Further, as the workability increases, the adhesiveness between the base steel sheet and the laminated resin layer decreases, but it is also an object of the present invention to ensure sufficient adhesiveness.

[0007]

According to the present invention, a two-piece can having a thin can wall can be easily processed by a dry method, and the processed can has sufficient pressure resistance and corrosion resistance. The purpose is to provide a thermoplastic resin-coated steel sheet having sufficient adhesion between the steel sheet and the coating resin layer even after the heating. This dry processability is enhanced,
In order to make the strength of the can suitable for the purpose of the present invention, the chemical composition of the steel sheet is determined, and the crystal grain size is 6 μm or more,
Yield strength 25-70kg / mm ² , tensile strength 25-7
3 kg / mm ² , plate thickness 0.15 to 0.30 mm, yield ratio 0.7 or more and less than 1, aging index 5 kg / mm ² or less. Further, in order to make the working adhesion between the steel sheet and the laminated thermoplastic resin problem-free, the steel sheet is subjected to electrolytic chromic acid treatment, and further the adhesion after working is further improved. The crystal grain size is set to 30 μm or less and the center line average roughness is set to 0.05 to 0.6 μm. Among the laminated thermoplastic resins, a crystalline polyester resin is preferable, its thickness is 10 to 50 μm, and its melting point is 1
80-260 degreeC is made into a more preferable range. By defining these various characteristics, the dry processability and the corrosion resistance after processing become excellent. Furthermore, as the thermoplastic resin, a polyethylene terephthalate resin and a copolyester resin mainly containing ethylene terephthalate units are more suitable. Further, the reason why the high temperature volatile lubricant is applied to the upper surface of the laminated thermoplastic resin layer is to enhance the dry processability, and the high temperature volatile lubricant can be removed by heating after the molding process, Steps such as degreasing, washing with water and drying can be omitted. As described above, by determining the chemical composition and properties of the steel sheet and the properties of the thermoplastic resin to be laminated and applying a high temperature volatile lubricant, dry processability, can strength, adhesion after processing, corrosion resistance It is possible to obtain a resin-coated steel sheet for dry-type drawing and ironing cans that has excellent properties. Here, in order to carry out the dry processing with a larger degree of processing without problems, it is desirable that the processing method is also suitable for the purpose of the present invention. The processing of the resin-coated steel sheet of the present invention is a composite processing method in which redrawing and ironing are performed under specific conditions, that is, damage of the thermoplastic resin layer laminated on the inner and outer surfaces and breakage of the can wall are less likely to occur. The characteristics of the resin-coated steel sheet of the present invention are more effectively exhibited by processing by the thick processing method.

[0008]

The reason for the limitation of the present invention and the operation thereof will be described in detail below. The present invention is a dry type, and can wall thickness is
The result of many studies, including the processing method, for the purpose of obtaining a resin-coated steel sheet that can be reduced in thickness to 0-40% and has excellent can strength, corrosion resistance, and adhesion. Is. The present invention, a steel plate laminated with a thermoplastic resin on both sides, dry type, and the problem to reduce the thickness of the can wall with a large degree of processing, the most problem to solve the problem, The heat generated by processing, softening and melting of the laminated thermoplastic resin layers due to the heat, resulting in direct contact between the base steel sheet and the mold, and further, breakage of the can wall. The heat generated by working is influenced by the deformation and friction of the metal plate, and the heat generated by deformation is smaller as the working degree and the deformation resistance are smaller. Further, in the ironing process in the combined machining shown in FIG. The smaller the value, the lower the surface pressure, and the smaller the frictional heat generation, which is proportional to the surface pressure x friction coefficient. Further, even if the laminated resin layers have the same temperature, the smaller the surface pressure is, the less the damage of the resin layers is. Therefore, regarding the damage of the resin layer, the damage of the resin layer is reduced if the deformation amount is small even if the working degree is the same and the deformation resistance of the material is as small as possible. Here, the material undergoes drawing and redrawing before the ironing process in FIG. 3, so that the less hardening due to the working is suitable for the purpose of the present invention. As described above, the chemical composition, crystal grain size, and aging index of the steel sheet are determined from the viewpoint that the deformation resistance is small even after working.

First, the reason for defining the chemical composition of the steel sheet will be explained. C hardens the steel by increasing its amount,
And the crystal grains are made finer. If the crystal grains are fine, the surface roughness due to the processing is small and it is desirable from the viewpoint of the adhesiveness to the laminated thermoplastic resin layer, but if the crystal grains are small, the curing due to the processing becomes large. The hardening of steel is not suitable for the dry processing which is the object of the present invention, and the upper limit of the amount of C is set to 0.1%.
On the other hand, when the C content is 0.001% or less, the work hardening is small, but the crystal grains become large, and the roughened surface is liable to occur even in the redrawing and ironing processes, which are premised on the application of the present invention. Processing adhesion to the resin layer, stress concentration due to rough skin occurs, and breakage easily occurs during processing.

Since Mn also hardens the steel, its content is preferably small, and its upper limit is limited to 0.5%. On the other hand, Mn is necessary to prevent hot brittleness due to S in steel,
The lower limit is set to 0.05%. Al is added as a deoxidizing agent, but if the deoxidizing residue is 0.015% or less, deoxidizing is unstable, while if it exceeds 0.13%, it hardens,
At the same time, it causes an increase in cost. When the amount of S increases, the amount of sulfide-based inclusions increases, the workability deteriorates, and the corrosion resistance decreases, so the upper limit is made 0.03%. Si,
Both P harden the steel and impede the dry processability, which is the subject of the present invention, so the respective upper limits are 0.05% and 0.05%.
It is set to 03%. The reason for adding Ti and Nb is to reduce the solute C and solute N in the steel and suppress work hardening.
If the amount is less than the lower limit, the effect is insufficient, and if it is more than the upper limit, the crystal grains become finer and the work hardening increases, which is not suitable for dry processing. In order to make the addition of Ti and Nb more effective, it is desirable to keep the C content at a low level. The C content is 0.001-0.05%, and further,
The range of 0.001 to 0.01% is more desirable. Also, N
Although the amount is not limited, it is preferably 0.005% or less. The effect of reducing solid solution C and solid solution N by adding Ti and Nb can be evaluated by the aging index described later.

Next, the grain size of steel is limited to 6 to 30 μm. In the present invention, the crystal grain size is defined as follows. That is, with a cross section parallel to the rolling direction of the steel sheet as the observation surface, the crystal grain size of three larger crystal grains observed in the range of 3 cm × 3 cm (actual size: 150 μm × 150 μm) in the visual field of 200 times magnification. The average value of is defined as the grain size of steel. Here, the crystal grain size of each crystal grain is an average value of the long dimension and the short dimension of the cross section of each crystal grain. Here, the long dimension is the length of the longest line segment among the line segments passing through the centers of the crystal grains. The length of a line segment that passes through the center of the crystal grain and is orthogonal to the long-dimension line segment is defined as the short dimension.
As described above, the reason for defining the crystal grain size by the size of the larger crystal grain observed on the observation surface of the steel cross section is as follows. That is, assuming that all the crystal grains of steel are spheres having the same diameter, the cross section of each crystal grain is observed as circles of various diameters in the cross section. Of these circles of various diameters, the largest one is the diameter of the sphere, that is, the true crystal grain size. From this, the size of the larger crystal grain observed on the observation surface of the steel cross section is defined as the crystal grain of steel. In the present invention, the smaller the crystal grain size is, the less the surface roughness due to processing is, which is preferable from the viewpoint of the work adhesiveness with the laminated thermoplastic resin, but the smaller the crystal grain size is, the larger the work hardening is, and the present invention is It deteriorates the dry processability, which is a problem. Since the resin-coated steel sheet of the present invention is premised on processing in which the can wall thickness is 70 to 40% of the original plate thickness, the blank diameter for obtaining a constant height may be smaller than that of a DTR can, and therefore The drawing ratio represented by (blank diameter / final can diameter) is small, so that roughening of the skin is unlikely to occur, and the crystal grain size does not need to be as small as the material for the DTR can. Rather, the smaller the size, the larger the work hardening as described above, and the dry processability is impaired. However, when the crystal grain size is 30 μm or more, roughening of the skin is likely to occur even if the above-mentioned drawing ratio is small, and there is a problem of poor adhesion of the laminated thermoplastic resin layers and breakage of the can wall. For the above reasons, the upper and lower limits of the crystal grain size are limited,
More desirably, a crystal grain size of 8 to 15 μm is suitable for the purpose of the present invention. The grain size of this steel is adjusted by changing the chemical composition of the steel, the finishing temperature of hot rolling, the winding temperature after hot rolling, and the recrystallization condition after cold rolling.

Next, the reason why the aging index is set to 5 kg / mm ² or less will be described. Aging index is solid solution C in steel
In proportion to the amount of solid solution N and the amount of solid solution N, work hardening increases when the amount of solid solution C and the amount of solid solution N are large. The aging index is used as a substitute value for the amount of solid solution C and the amount of solid solution N. The reason why the aging index is 5 kg / mm ² or less is to suppress hardening due to processing. In addition,
This aging index gives a strain of 8 to 10% to the steel plate and is 10
It is indicated by the difference between the yield strength value after heating at 0 ° C. for 1 hour and the yield strength value before heating. The aging index is adjusted by the winding temperature after hot rolling, the cooling rate during recrystallization annealing, the addition of Ti and Nb, and the like.

On the other hand, the processed can is used under a positive pressure or a negative pressure inside the can. To withstand such pressure, both the can bottom and the can wall must have a certain strength or more. .
In particular, when the pressure inside the can is positive, the pressure resistance of the bottom of the can becomes a problem, but since the pressure resistance is roughly (plate thickness) ² x the yield strength, it directly affects the plate strength and yield strength. Strength affects. Moreover, the required pressure resistance also differs depending on the contents. The yield strength, tensile strength, and lower limit of the plate thickness of the steel sheet are determined in consideration of this compressive strength. Further, the upper limits of the yield strength and the tensile strength are limited in terms of damage to the laminated resin layers during ironing. In consideration of these points, the yield strength and tensile strength of the steel sheet used in the present invention, respectively 25~70kg / mm ^2, is limited to 25~73kg / mm ^2. When it is at least the upper limit, breakage of the can wall easily occurs due to damage of the resin layer. Furthermore, the yield ratio expressed by the yield strength / tensile strength is set to 0.7 or more and less than 1,
This is because the yield strength that affects the strength of the bottom of the can is high, while the deformation resistance during processing that affects the damage of the resin layer during ironing is smaller for the purpose of the present invention. , The lower limit was set. The upper limit of the plate thickness of the steel sheet is 0.3 mm or less from the viewpoint of the pressure resistance of the obtained can body, and the upper limit is 0.3 mm from the economical point of view. When the yield strength or the tensile strength is large, the thickness of the steel sheet can be reduced in terms of the strength of the can. When using a steel plate having a high yield strength, it is desirable that the original plate thickness of the steel plate is as thin as possible as long as the can strength is higher than necessary. Even if the degree of processing is the same, the amount of processing can be reduced and the heat generation during processing can be reduced when the original plate thickness is thinner. The reason for limiting the lower limit of the steel plate thickness to 0.15 mm is
This is because the steel plate having a uniform thickness is continuously and stably produced at high speed, and the lower limit is not limited.

Next, the resin to be laminated on the steel sheet is a thermoplastic resin, preferably a crystalline polyester resin having a thickness of 10 to 50 μm, and further 180 to 260.
A polyester resin having a melting point of ° C. The reason will be described. The present invention is premised on dry processing, but by using a thermoplastic resin as the resin to be laminated,
The lubrication effect during ironing becomes more effective. During the ironing process, the outer surface of the can generates heat due to friction with the ironing die, but it is presumed that the heat generated softens and causes a lubricating action. When the temperature of the ironing die is raised, the lubricating effect becomes remarkable, but when the temperature is further raised, the resin in the ironing die is further softened, and the surface pressure proportional to the deformation resistance of the steel sheet cannot be fully resisted. Come into direct contact with each other, causing breakage of the can wall. Therefore, it is not preferable that the thermoplastic resin is excessively softened, and it is desirable that the ironing die temperature is in an appropriate temperature range, preferably 25 ° C. to the glass transition temperature of the laminated thermoplastic resin. On the other hand, it is not preferable that the laminated thermoplastic resin also softens at a low temperature, and if the melting point is used as an index of the ease of softening, it is preferable to use a thermoplastic resin having a melting point of 180 ° C. or higher. It is more preferable because the steel sheet improves the formability in the dry processing targeted. That is, in industrial production, drawing and ironing are carried out continuously, but in that case, the can wall temperature may be 100 ° C or higher, depending on the processing conditions, and if the melting point is low, it softens or melts. The appearance of the obtained can body is impaired, or an exposed iron portion is formed on the inner surface of the can, so that the corrosion resistance decreases. Further, the thermoplastic resin adheres to the tool, which makes continuous production difficult. 1 from this point
It is preferable to use a thermoplastic resin having a melting point of 80 ° C. or higher. Further, the melting point of the laminated thermoplastic resin is 26.
If it is 0 ° C or higher, a sufficient lubricating effect due to softening during processing cannot be obtained. For the above reasons, it is more preferable to limit the melting point of the laminated thermoplastic resin to 260 ° C and the lower limit to 180 ° C. The thickness of the laminated thermoplastic resin layer is 10 to 50 μm, but the thickness is 10
When the thickness is less than μm, the risk of direct contact between the ironing die for the outer surface of the can and the base steel plate during ironing becomes great, and the risk of breakage of the can wall increases. Further, the corrosion resistance on the inner surface side of the can may be insufficient. Further, it becomes difficult to continuously and stably laminate the thermoplastic resin on the steel sheet. On the other hand, the upper limit of the thickness of the laminated thermoplastic resin is 5 because wrinkles are likely to occur at the time of drawing and economical efficiency is 5
It is limited to 0 μm.

Among the thermoplastic resins having a melting point of 180 to 260 ° C., a more preferable resin is a polyester resin, and specifically, a polyethylene terephthalate, polybutylene terephthalate, and a copolymerized polyester resin mainly containing ethylene terephthalate units. Or a polyester resin composed of a mixture thereof. Especially 7
5 to 95 mol% polyethylene terephthalate and 5 to 2
A copolymerized polyester resin composed of 5 mol% of polyethylene isophthalate, polyethylene sebacate or polyethylene diapate, polyethylene terephthalate, or a polyester resin obtained by blending the above polyester resin with polybutylene terephthalate is preferable.

As a method for laminating the above polyester resin on a steel sheet, a method of extruding and laminating a molten polyester resin directly on both sides of the steel sheet, a method of forming a film by melt extrusion and then forming an unstretched or stretch-oriented film by a conventional method is performed. There is a method of laminating by fusion bonding or via an adhesive, and a method in which these methods are used in combination, and any method is applicable as a method for producing the resin-coated steel sheet of the present invention, but it is formed. In the can, it is preferable to use a biaxially oriented polyester resin film from the viewpoints of impact workability of the laminated resin layers, permeation resistance to highly corrosive contents, and the like. In that case, the plane orientation coefficient of the polyester resin layer laminated by heat fusion is 0.01 to 0.10 on the surface not in contact with the steel sheet (free surface), and 0.00 to 0.05 on the surface in contact with the steel sheet. It is most preferable to select the laminating conditions so as to fall within the range of. That is, when the surface orientation coefficient of the surface of the laminated polyester resin layer in contact with the steel sheet is 0.05 or more, the laminated polyester resin layer is likely to peel off during processing, which is not practical.

On the other hand, when the plane orientation coefficient on the free surface of the laminated polyester resin layer is 0.01 or less,
The biaxial orientation of the polyester resin has almost disappeared, and when the ironing and squeezing can is dry-processed, cracks may form in the laminated polyester resin layer, and the can is filled with highly corrosive contents. It is difficult to use. Further, if the plane orientation coefficient on the free surface exceeds 0.10, the spreadability of the laminated polyester resin layer becomes poor, and if the processing conditions become severe, the resin layer may be cracked during processing. Therefore, in the resin-coated steel sheet of the present invention, the plane orientation coefficient of the free surface of the laminated polyester resin layer is 0.01 to 0.10, and the plane orientation coefficient of the surface in contact with the steel sheet is 0.00 to 0.05. It is preferably within the range. Incidentally, it is preferable to laminate the above polyester resin film on a steel sheet via an adhesive layer for the inner surface of a can filled with highly corrosive contents, and in that case, the plane orientation coefficient of the laminated polyester resin layer. Does not need to be controlled as described above. Known adhesives can be used as the adhesive used, but a thermosetting polymerization composition having an epoxy group in the molecule is more preferable, and the adhesive is applied to the surface of the thermoplastic resin film in contact with the steel sheet, or even dried, or You may apply and dry on the surface of a steel plate.

The plane orientation coefficient of the laminated polyester resin layer is determined by the following method. First, a polyester resin-coated steel sheet is immersed in dilute hydrochloric acid to dissolve the steel sheet, and only the polyester resin layer is collected. Next, the collected polyester resin layer (film) is washed with water and dried,
The refractive index in each of the length direction, the width direction and the thickness direction on each surface (the surface in contact with the steel plate and the free surface) of the film is measured using a refractometer. Using this refractive index, the plane orientation coefficient on each side of the film is calculated by the following formula. A = (B + C) / 2−D where A is the plane orientation coefficient of the film, B is the refractive index in the length direction of the film, C is the refractive index in the width direction of the film, and D is the thickness of the film. The refractive index in the vertical direction is shown. Since the refractive index measured by the above method shows an average value within a thickness of 5 μm from each surface of the film,
Each side of the film (the side that was in contact with the steel plate and the free side)
It is possible to distinguish between the plane orientation coefficients of.

Further, in the present invention, it is easy to control the plane orientation coefficients of the surface of the polyester resin layer laminated by heat fusion which is not in contact with the steel sheet (free surface) and the surface which is in contact with the steel sheet within a preferable range. Therefore, it is also possible to use a biaxially oriented film of a polyester resin composed of two layers of an upper layer resin and a lower layer resin having different melting points.

IV value of the above polyester resin film
(Intrinsic viscosity, intrinsic viscosity) is also one of the important factors of the polyester resin film used in the present invention. The IV value has a positive correlation with the molecular weight, and is a factor that greatly affects the rigidity of the film and the moldability of the resin film.
That is, when the IV value is 0.50 or less, the impact resistance after forming into a drawn and ironed can is poor even if the plane orientation coefficient of the laminated polyester resin layer is in a preferable range,
Countless minute cracks occur in the polyester resin layer on the inner surface side of the impacted portion, and the steel surface is exposed. When the IV value is 0.70 or more, viscous resistance is high during ironing, which may cause a problem in practical use.

In the present invention, it is also an important factor from the aesthetic point of view to laminate a thermoplastic resin colored with a pigment on the surface of the steel sheet which is the outer surface of the can. That is, in order to improve the clarity of the design printed on the outer surface of the can, it is possible to include a titanium oxide-based white pigment in the resin manufacturing process. As the pigment, inorganic pigments, organic pigments, and pigments of colors other than white can be applied and are selected according to the application. A good printability can be obtained with an addition amount of 1 to 20%.

Further, in the present invention, bisphenol A
Polycarbonate, 6-nylon, 6,6-nylon,
It is also possible to use polyamide resins such as 6-6,6-copolymer nylon, 6,10-nylon, 7-nylon and 12-nylon, or thermoplastic resins such as polyethylene naphthalate. Furthermore, it is also possible to use these thermoplastic resins alone, as a two-layer structure obtained by co-extrusion with the polyester resin, or the upper layer of a three-layer structure film, or as an intermediate layer,
Further, it is also possible to use a resin obtained by blending these thermoplastic resins with the polyester resin. Further, it is also possible to apply a two-layer film provided with the above polyester resin layer as an upper layer of the blend resin film. If necessary, additives such as a stabilizer, an antioxidant, an antistatic agent, a lubricant, and a corrosion inhibitor may be added to the above thermoplastic resin as long as other properties are not impaired.

The steel sheet on which the thermoplastic resin is laminated is preferably an electrolytic chromic acid treated steel sheet, and the center line average roughness of the steel sheet to be used is 0.05 to 0.5 μm because the thermoplastic resin laminated on the steel sheet. This is for the purpose of achieving adhesion with and corrosion resistance. The film formed by the electrolytic chromic acid treatment is a film having a two-layer structure in which the lower layer is metallic chromium and the upper layer is chromium hydrated oxide, the amount of metallic chromium in the lower layer is 30 to 200 mg / m ² , and the upper layer is chromium. The hydrated oxide preferably has a chromium content in the range of 5 to 25 mg / m ² . When the center line average roughness is 0.6 μm or more, depending on the processing conditions, the processing adhesion of the laminated thermoplastic resin becomes a problem, and the laminated thermoplastic resin layer peels off at the upper end of the can with a large degree of processing. However, the upper limit was set to 0.6 μm. Further, the lower limit is not from the viewpoint of performance, but it is difficult to economically produce a steel sheet having a center line average roughness of 0.05 μm or less stably. From this point, the lower limit is set to 0.05 μm.

The high temperature volatile lubricant applied to the upper surface of the laminated thermoplastic resin layers plays an important role in carrying out the dry processing, which is the subject of the present invention, at a high processing rate and at a high speed. Also, high temperature volatile lubricants are
When heated at a temperature of about ℃ for a few minutes, it is desirable to scatter by 50% or more. Specifically, liquid paraffin, synthetic paraffin, natural wax, etc., as a simple substance, or a mixture thereof, processing conditions, after processing Select according to the heating conditions of. The characteristics of the applied lubricant are that the melting point is 25 to 8
Those having a temperature of 0 ° C. and a boiling point of 180 to 400 ° C. are desirable for the purpose of the present invention. Further, the coating amount should be determined in consideration of the surface to be the outer surface of the can, the surface to be the inner surface of the can, processing conditions, heating conditions after processing, etc.
A range of mg / m ² , preferably 30-60 mg / m ² , is suitable.

As described above, by limiting the chemical composition and characteristics of the steel sheet and the characteristics of the thermoplastic resin, and further applying a high temperature volatile lubricant on the laminated thermoplastic resin, the dry drawing and ironing A resin-coated steel sheet suitable for forming a can having a thin can wall having a can height as high as about twice the can diameter and a can wall thickness of about 70 to 40% of the original plate thickness is obtained by processing.

The drawing and ironing process will be described below. The object of the present invention can be achieved very effectively if the thickness of the can wall is reduced by the combined processing of simultaneously performing redrawing and ironing. One aspect of a process for producing a can having a high can height and a thin can wall thickness from the resin-coated steel sheet of the present invention by processing including the composite processing will be described below. First, as shown in FIG. 2, from the resin-coated steel sheet shown in FIG. 1, a blank 5 is punched out into a squeezing can 6, and the squeezing can 6 is converted into a re-squeezing can 7 having a smaller diameter than the squeezing can 6. As shown in FIG. 3, while redrawing the redrawing can 7 into a can having a small diameter, at the same time, a step of forming a drawn and ironed can 8 by combined processing of ironing, and further, trimming the upper end of the can, The trim can 12 is formed, and then the top end of the can is necked in (processing for reducing the diameter of the can) and flanged to obtain the final can shown in FIG. The resin-coated steel sheet of the present invention has a problem of obtaining a can having a high height and a thin can wall thickness. In the above process, the role of the composite processing is not small, and an outline of the composite processing is shown in FIG. In the composite processing, the re-drawing die 14 is followed by the ironing portion 16, and the ironing is performed while the re-drawing is performed. By performing the ironing while effectively applying the rearward tension to the ironing portion in this way, the resin layer on the outer surface is less likely to be damaged. Further, the length L of the can wall 10 between the redrawing portion and the ironing portion is determined in consideration of the dimension to be thickened for the subsequent neck-in processing. Further, if the temperature of the redrawing die 14 and the ironing die 15 is set in the range of 25 ° C. to the glass transition temperature of the laminated resin, it is effective in solving the problems of the present invention. Here, an electrolytic chromic acid treated steel plate coated with a thermoplastic resin and having an original plate thickness of 0.20 mm was processed according to the processing steps of FIG. 2 and trimmed, and the can wall thickness in the can height direction (laminated FIG. 5 shows an example of the distribution of the thickness of only the steel sheet from which the resin layer has been peeled off.
In Fig. 5, the thickness of the can body is as thin as about 0.120 mm (40% reduction from the original plate thickness), and the top of the can is about 0.1
It is as thick as 60 mm (reduced by 20% from the original plate thickness) and is in a state suitable for subsequent neck-in processing. Also, FIG.
As will be easily understood from the processing method of No. 3, when the outer diameter of the punch 13 is the same in the portion corresponding to the can body and the portion corresponding to the can upper end, the thickness difference between the can body and the can upper end is It is formed on the outer surface of the can and is in the opposite state to the DI can having a thickness step on the inner surface of the can. 2, FIG. 3, FIG. 4 and FIG. 5 show an aspect in which a thickness step is formed on the outer surface side of the can. On the other hand, needless to say, as in the case of the DI can, if the outer diameter of the punch corresponding to the upper end of the can is reduced, a thickness step is formed on the inner surface of the can. Even if there is a step on the outer surface of the can,
The appearance is hardly affected, and even if there is a step on the inner surface of the can, the detachability of the punch of the can after molding is hardly affected. That is, regardless of whether the step is formed on the inner surface side or the outer surface side, there is no problem in terms of quality and manufacturing.

[0027]

【Example】

Example 1 Six types of steel having the chemical compositions shown in Table 1 were melted in a converter to form a slab, hot rolling was completed at a finishing temperature of 900 ° C., and rolling was performed at 650 ° C., and a hot rolling of 1.8 mm was performed. It was a plate.
The hot-rolled sheet was pickled and cold-rolled to give sheet thicknesses of 0.2 mm and 0.3 m.
m cold-rolled sheet and the recrystallization annealing (C
A: continuous annealing, BA: box-type annealing) were performed. Next, the 0.2 mm thick steel plate was an SR material that was skin-passed at a reduction rate of 1 to 2%, and the 0.3 mm thick steel plate was 0.
The DR material was rolled to 2 mm. The SR material, DR
Material is treated with electrolytic chromic acid (Amount of chromium metal: 120 mg / m
² , chromium content in hydrated chromium oxide: 18 mg / m ² )
Then, 11 kinds of steel plates shown in Table 3 were used as the original plates for thermoplastic resin lamination. These electrolytic chromic acid treated steel sheets were coated with a thermoplastic resin in the following manner. First, these original plates were heated to 240 ° C., and a biaxially stretched copolymerized polyester resin film (thickness: 25 μm, surface: polyethylene terephthalate 88 mol%, polyethylene isophthalate 12 mol%) was formed on the inner surface of the can. Orientation coefficient: 0.1
26, melting point: 229 ° C., and a biaxially stretched copolyester resin film (thickness: 2) of the same composition as the above, which was colored white with a titanium oxide pigment added to the outer surface of the can.
0 μm) were laminated at the same time, and immediately immersed in water and cooled.
After laminating, it was dried, and paraffin wax was applied on both sides of the layer at about 50 mg / m ² for subsequent processing. First,
After punching into a blank with a diameter of 160 mm, the can diameter is 100
mm squeeze can. Then, by redrawing, the can diameter is 80.
mm redrawing can. This re-drawing can was subjected to redrawing and ironing at the same time by a composite process to obtain a drawn and ironed can having a can diameter of 66 mm. In this combined processing, the distance between the redrawing part and the ironing part, which are the upper end of the can, is 20 m.
m, the shoulder radius of the redrawing die is 1.5 times the plate thickness, the clearance between the redrawing die and the punch is 1.0 times the plate thickness, and the clearance at the ironing part is 55% of the original plate thickness. processed. In any process, water-based cooling, no lubricant is used, dry process is performed, whether or not the can wall is broken, the outer surface of the can, the metal exposed on the inner surface of the can, and the resin layer laminated with the electrolytic chromic acid treated steel plate of the base. Was evaluated. In this composite processing, the composite is molded in the direction of the arrow, the molding is finished with the flange left on the upper end of the can, the punch is retracted, and the can after the composite molding is taken out in the direction opposite to the arrow. Then, by trimming the upper end of the can and subjecting it to neck-in processing and flange processing, the resin-coated steel plate of the present invention has a high can height, a thin can wall thickness, and a state in which the can lid can be tightened. It becomes a can of. The fracture rate of the can wall, the state of the outer surface of the can, the metal exposure on the inner surface of the can, and the adhesiveness of the resin layer laminated with the base steel sheet were evaluated according to the following criteria. 1) Breakage rate of can wall ◎: 0%, ◯: less than 10%, Δ: 10% or more, less than 30%, ×: 30% or more 2) State of outer surface of can (evaluated by flaw occurrence rate) ◎: 0 %, ◯: less than 10%, Δ: 10% or more, less than 30%, x: 30% or more 3) Metal exposure (enamel lator value (ERV: ERV:
mA)) ◎: 0 or more, less than 0.05 mA, ◯: 0.05 mA or more,
Less than 0.5 mA, Δ: 0.5 mA or more, less than 5 mA, x:
5 mA or more 4) Processing adhesion of laminated resin layers (Evaluated by the degree of peeling after neck-in processing) ◎: No peeling at all, ○: Peeling slightly, but practically no problem, Δ: Peeling considerably, ×: The entire top of the can is peeled off

Example 2 Steel plates C-1, C-2, D-1, and D-2 shown in Table 2 were treated with electrolytic chromic acid in the same manner as in Example 1 (the amount of metallic chromium: 75).
mg / m ² , chromium content in hydrated chromium oxide: 13 mg
/ M ² ), and used as the original plate for the thermoplastic resin lamination. These electrolytic chromic acid-treated steel sheets were heated to 240 ° C., and a biaxially stretched copolyester resin film made of 88 mol% polyethylene terephthalate and 12 mol% polyethylene isophthalate was formed on the inner surface of the can (thickness:
12 μm, plane orientation coefficient: 0.126, melting point: 229
℃), add titanium oxide pigment to the outer surface of the can,
A biaxially stretched copolyester resin film (thickness: 12 μm) having the same composition as the above, which was colored white, was laminated at the same time and immediately immersed in water and cooled. Then, after drying, about 50 mg / m ² of paraffin wax was applied on both surfaces. After that, molding was performed under the same conditions as in Example 1, and evaluation was performed in the same manner as in Example 1.

Example 3 Steel plates D-1 and D-2 shown in Table 2 were subjected to the same electrolytic chromic acid treatment as in Example 1 (metal chromium amount: 135 mg / m ² , chromium amount in chromium hydrate oxide: 15 mg). / M ² ),
It was used as the original plate for coating the thermoplastic resin. These electrolytic chromic acid-treated steel sheets were heated to 235 ° C., and on the inner surface of the can, an upper layer was a copolymerized polyester resin layer composed of 88 mol% polyethylene terephthalate and 12 mol% polyethylene isophthalate, and a lower layer was polyethylene terephthalate 94.
Biaxially stretched bilayered copolyester resin film of copolyester resin layer consisting of mol% and polyethylene isophthalate 6 mol% (upper layer thickness: 15 μm, lower layer thickness: 5 μm, upper layer melting point: 229 ° C.) , The melting point of the lower layer: 226 ° C., the plane orientation coefficient of the upper layer: 0.123, and the plane orientation coefficient of the lower layer: 0.083). The outer surface of the can was colored white with the same composition as in Example 1. An axially stretched copolyester resin film (thickness: 15 μm) was laminated at the same time and immediately immersed in water and cooled. Then, after drying, about 50 mg / m ² of paraffin wax was applied to both surfaces. After that, molding was performed under the same conditions as in Example 1, and evaluation was performed in the same manner as in Example 1.

Example 4 Steel plates C-1, C-2, D-1 and D-2 shown in Table 2 were subjected to the same electrolytic chromic acid treatment as in Example 1 (the amount of metallic chromium: 95).
mg / m ² , chromium content in hydrated chromium oxide: 15 mg
/ M ² ) to give a base plate for laminating a thermoplastic resin. These electrolytic chromic acid-treated steel sheets were heated to 240 ° C., and the inner surface of the can was coated with an epoxy / phenolic primer in a dry weight of 0.5 mg / m ² on the surface of polyethylene terephthalate. A biaxially stretched copolymer polyester resin film (thickness: 20 μm, plane orientation coefficient: 0.126, melting point: 229 ° C.) consisting of 88 mol% and polyethylene isophthalate 12 mol% was applied to the outer surface of the can. A titanium oxide pigment having the same composition as in Example 1 was added, and a biaxially stretched copolyester resin film colored in white (thickness: 15 μm) was simultaneously laminated, and immediately immersed in water and cooled. Then, after drying, about 50 mg / m ² of paraffin wax was applied on both surfaces. After that, molding was performed under the same conditions as in Example 1, and evaluation was performed in the same manner as in Example 1. The evaluation results are shown in Tables 3 and 4, and the thermoplastic resin-coated steel sheet of the present invention is suitable for cans that are dry-formed and have a high can height and a thin can wall thickness. I understand.

[0031]

[Table 1] Note) The symbol (-) in the table means no addition.

[0032]

[Table 2]

[0033]

[Table 3]

[0034]

[Table 4]

[0035]

INDUSTRIAL APPLICABILITY The resin-coated steel sheet for a dry drawn and ironing can of the present invention is dry, suitable for forming an ironed can having a high can height and a thin can wall thickness.

[Brief description of drawings]

FIG. 1 is a schematic view showing a cross section of a resin-coated steel sheet for a dry drawn and ironing can of the present invention.

FIG. 2 is a schematic view related to one embodiment of a process of introducing a dry can, which has a high can height and a thin can wall, from a resin-coated steel sheet for a dry drawn and ironed can of the present invention.

FIG. 3 is a combination of dry drawing, ironing, and resin-coated steel sheet for cans, which is a combination of dry drawing, re-drawing suitable for guiding a can with a high can height and thin can walls, and ironing. It is a schematic diagram of a partial cross section.

FIG. 4 is a sectional view of a can formed from the resin-coated steel sheet for a dry drawn and ironed can of the present invention.

FIG. 5 is a diagram showing an example of a can wall thickness profile of a can formed from the resin-coated steel sheet for a dry drawn and ironed can of the present invention.

[Explanation of symbols]

 1 Steel Plate 2 Thermoplastic Resin Layer 3 Electrolytic Chromic Acid Treatment Film 4 High Temperature Volatile Lubricant 5 Blank 6 Drawing Can 7 Redrawing Can 8 Redrawing Ironing Can 9 Thin Can Wall 10 Can Upper End 11 Remaining Flange 12 Trim Can 13 Punch 14 Redrawing die 15 Ironing die 16 Ironing part 17 Wrinkle retainer 18 Arrow 19 Can bottom 20 Neck L Distance between redrawing part and ironing part

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location B32B 15/08 F

Claims (5)

[Claims] 1. C amount: 0.001 to 0.10%, Mn amount: 0.05 to 0.50%, Al amount: 0.015 to 0.13
%, Si amount ≤0.05%, P amount ≤0.03%, S amount ≤0.0%.
03%, the balance consists of Fe and inevitable impurities,
Crystal grain size: 6 to 30 μm, center line average roughness: 0.05 to
Dry squeeze ironing, in which both sides of an electrolytic chromic acid treated steel sheet with a thickness of 0.6 μm and a thickness of 0.15 to 0.30 mm are coated with a thermoplastic resin with a thickness of 10 to 50 μm, and a high temperature volatile lubricant is applied to the surface. Resin coated steel sheet for processing cans. 2. C amount: 0.001 to 0.05%, Mn amount: 0.05 to 0.50%, Al amount: 0.015 to 0.13
%, Si amount ≤0.05%, P amount ≤0.03%, S amount ≤0.0%.
In addition, the content of Nb and Ti is 0.001 to 0.03%, 0.005 to 0.005%, respectively.
05% content, the balance consisting of Fe and inevitable impurities, crystal grain size: 6 to 30 μm, center line average roughness: 0.0
A dry type in which both sides of an electrolytic chromic acid treated steel plate having a thickness of 5 to 0.6 μm and a thickness of 0.15 to 0.30 mm are coated with a thermoplastic resin having a thickness of 10 to 50 μm, and a high temperature volatile lubricant is applied to the surface thereof. Resin coated steel sheet for drawn and ironed cans. 3. The yield strength of the steel sheet according to claim 1 or 2 is 25 to 70 kg / mm ² , and the tensile strength is 25 to 73 kg.
/ Mm ² , yield ratio 0.7 or more, less than 1, aging index 5
Resin-coated steel sheet for dry drawing and ironing cans that is less than kg / mm ² . 4. A resin-coated steel sheet for a dry drawn and ironed can, wherein the thermoplastic resin according to claim 1 or 2 is a crystalline polyester resin. 5. The resin-coated steel sheet for a dry drawn and ironed can according to claim 1 or 2, wherein an adhesive layer is interposed between the electrolytic chromic acid treated steel sheet and the thermoplastic resin layer.