JP4898130B2 - Steel plate for canned ironing can excellent in inner surface corrosion resistance and outer surface printability, can body and manufacturing method thereof - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a steel sheet for a drawn iron can, which is excellent in inner surface corrosion resistance and outer surface printability, in which a polyester resin film is firmly laminated on a Ni thin layer plating of a steel sheet, and a method for producing the same.

Prior to the use of laminated steel sheets, tin plates plated with tin (Sn) having excellent solid lubricity were the mainstream as the steel sheet material for drawn irons. Tin-drawn ironing cans are painted for the purpose of ensuring corrosion resistance after drawing and ironing.
However, since the forming tool and the tinplate surface naturally come into contact with each other at the time of molding the can, the surface Sn may be scraped and the iron surface may be exposed.

In particular, the higher the degree of processing of the side wall of the can (the following mathematical formula 1), the higher the surface pressure between the forming tool and the material to be formed, so that the Sn on the surface is easily cut and the risk of exposing the iron surface increases. To do.
Degree of processing (%) = ((original plate thickness−can side wall thickness) / original plate thickness)) × 100 (1)
In such a portion where the iron surface is exposed, even after coating, corrosion under the coating film may occur after filling and sealing the content, which may be a problem in terms of content preservation.

  Also, in recent years, there are environmental problems such as wastewater treatment in the can manufacturing process, carbon dioxide emission, etc., and in order to eliminate the need to paint the molded can body, a polyester film is previously applied to the surface of the electrochromated steel sheet. A two-piece can made of a coated steel sheet has been proposed. Among them, Patent Document 1 (Japanese Patent Publication No. 3-33506) discloses a steel sheet that is provided with a coating layer of a thermoplastic polyester resin on a surface treatment film on the steel sheet surface that is the inner surface side of the can, and that is the outer surface side of the can. A proposal has been made that a steel plate with a malleable metal plating on the surface is subjected to the ironing rate specified in a specific range, but this is not sufficient in terms of corrosion resistance.

  Further, in Patent Document 2 (Japanese Patent Laid-Open No. 7-164068), a steel plate coated with a polyester film on the surface of a Sn-plated steel plate is used as a material, and the effective coverage of Sn is 85% or more, A squeezed iron can has been proposed in which Sn of the neck portion and the flange portion is not reflowed. Particularly, since the Sn of the neck portion and the flange portion is not reflowed, the adhesion of the polyester film coating after processing is improved. Inadequate and not enough in terms of corrosion resistance

  In particular, in the case of a film covered with a metal plate corresponding to the outer surface side of the can, the outer surface film is scraped at the point of action of the ironing process of the die as the side wall of the can becomes higher, and enters the height direction of the can. Film wrinkles (commonly called “kajiri”) are likely to occur. When such a film wrinkle occurs on the outer surface of the can, the wrinkle often does not disappear even after printing or painting on the outer surface, which is a serious problem that significantly deteriorates the printed appearance and greatly affects the production yield.

  As for the outer surface of cans, for example, even if you look at coffee cans filled with coffee, each company is filling various types of coffee and providing them to the market. The appearance of printing has become an important appealing point. Under such circumstances, a whiter base is required from the point of sharpness and beauty of the printed appearance.

Against such a background, a film containing a white pigment such as titanium oxide in the film is disclosed in, for example, Patent Document 3 (Japanese Patent Laid-Open No. 05-170942), Patent Document 4 (Japanese Patent Laid-Open No. 05-339391), and the like. Has been proposed in
However, since the laminated metal plate obtained from the above proposal is a single-layer film, the above-mentioned “galling” occurs, and there is a problem as an outer surface film.

Therefore, a double-layered film such as Patent Document 5 (Japanese Patent Laid-Open No. 08-169098) or Patent Document 6 (Japanese Patent Laid-Open No. 2001-171062), or Patent Document 7 (Japanese Patent Laid-Open No. 2002-240224). A three-layered film has been proposed.
However, even with laminated metal plates coated with such films, the occurrence of galling is inevitable when drawing and squeezing is performed at a high speed and with a high degree of processing, and there are almost no inventions or proposals for anti-galling measures. is there.

Japanese Patent Publication No.03-33506 Japanese Patent Application Laid-Open No. 07-164068 JP 05-170942 A JP 05-339391 A Japanese Patent Laid-Open No. 08-169098 JP 2001-171062 A Japanese Patent Laid-Open No. 2002-240224 Japanese Patent Laid-Open No. 08-50091

  The present invention provides a steel plate for a squeezed iron can excellent in inner surface corrosion resistance and outer surface printability, a can body, and a method for producing the same.

The present invention has the following configuration.
(1) In the drawn and ironed steel sheet for cans having a thermoplastic resin film layer on both surfaces of the steel sheet, the amount deposited on the surface of the steel sheet is Ni-plated layer of 100-2000 mg / m ^2, of 0.1 to 15 mg / m ² on its surface Polyester resin having a thickness of 8 to 25 μm on the surface corresponding to the inner surface side of the can of the Ni-plated steel plate having a chromate film layer composed of Cr and hydrated Cr of 0.2 to 30 mg / m ^{2 in} terms of metal Cr. The film is laminated on the surface corresponding to the outer surface side of the can through an adhesive primer layer having a thickness of 2 to 7 μm and a polyester resin film having a thickness of 8 to 25 μm containing 20 to 70% by weight of white and / or colored pigment. is and and Ri density 1.360g / cm ³ der following polyester resin film as the outer surface of the can, the surface corresponding to the outer surface side of the surface and the can corresponding to the inner surface of the can The polyester resin film to be layered is a crystalline polyester resin having a melting point (Tm) of 230 ° C. or higher, a crystal melting heat (Hm) and / or a cold crystallization heat (Hm) of 20 to 45 J / g, and a glass transition. A polyester resin film laminated steel sheet for a drawn ironing can excellent in inner surface corrosion resistance and outer surface printability, characterized by having a temperature (Tg) of 60 ° C. or more and an intrinsic viscosity (IV) of 0.58 dl / g or more .

(2) A polyester resin film having a thickness of 8 to 50 μm is laminated on a steel sheet surface which is an inner surface side of the can through an adhesion primer layer having an adhesion amount of 700 to 3000 mg / m ^2. (1) Polyester resin film laminated steel sheet for drawn iron cans having excellent inner surface corrosion resistance and outer surface printability.

(3) In the can formed by forming the polyester resin film laminated steel sheet according to (1) or (2), the average thickness of the polyester resin film in the side wall portion of the inner surface of the can is 5 to 30 μm, and the can side wall The peel strength of the polyester resin film coating in the part is 500 g / cm, and the exposure rate of Fe under the resin film layer on the inner surface side of the can is at least less than 50%, and the average Ni in the side walls on the inner and outer surfaces of the can A squeezing and ironing can excellent in inner surface corrosion resistance and outer surface printability, characterized in that the coating amount is 50 to 700 mg / m ² .

(4) After the polyester resin film laminated steel sheet according to (1) or (2) is drawn and ironed, the polyester resin film coated on the inner and outer surfaces of the can is heated above the higher melting point of the polyester resin film and then rapidly cooled. In addition, the density of the polyester resin film coated on at least the inner surface side of the can is 1.360 g / cm ³ or less, and there is a manufacturing method of a drawn iron can excellent in inner surface corrosion resistance and outer surface printability. .

  According to the present invention, a squeezed iron can having good inner surface corrosion resistance and good outer surface printability can be obtained. Moreover, it becomes possible to manufacture it stably.

The present invention is described in detail below. First, excellent drawing and ironing a polyester resin film laminated steel sheet for cans on the inner surface corrosion resistance and an outer surface printability of the present invention, Ni deposition amount is 100-2000 mg / m ^2, of 0.1 to 15 mg / m ² on its surface Polyester having a thickness of 8 to 50 μm on one side of the inner surface of the can of a Ni-plated steel plate having a chromium coating layer made of Cr and hydrated Cr of 0.2 to 30 mg / m ^{2 in} terms of metal Cr. A resin film is laminated, and a polyester resin film having a thickness of 8 to 25 μm contains white and / or colored pigments in an amount of 2 to 7 μm in thickness on an outer surface side of the can through an adhesive primer layer having a thickness of 2 to 7 μm. The density of the polyester resin film which is laminated and becomes the outer surface side of the can is 1.360 g / cm ³ or less.

  The base material of the polyester resin film laminated steel sheet used in the present invention is not particularly limited, but it is preferable to use a steel sheet that is usually used for a drawn iron can, and the thickness is 0.12 to 0.60 mm. It is in the range and the hardness (HR30T) is preferably 46 to 68. When a thermoplastic resin film is laminated on a surface-treated steel sheet with metal plating and squeezing and ironing, the processing tool and the metal plating layer do not touch each other directly, and the thermoplastic resin film acts as a buffer material. It has already been known from past studies that the damage of the metal plating layer can be greatly reduced as compared with the case where there is no resin film.

From various studies by the inventors, among metal platings, especially Sn and Ni are excellent in the spread of the metal itself, so that the Fe surface exposure of the steel sheet is small, but Sn has a low melting point and is generated by heating. It has been found that the oxide layer is brittle and is not preferable from the viewpoint of adhesion, and by using Ni, it is possible to reduce both the exposure of iron and ensure the adhesion of the laminate coating.
Ni deposition amount of the polyester resin film laminated steel plate of the present invention are 100-2000 mg / m ^2, 0.2 to a metal Cr and Cr metal equivalent amount of 0.1 to 15 mg / m ² on the surface of the Ni plating layer It is optimal to have a chromate coating layer consisting of 30 mg / m ² of hydrated Cr oxide.

In addition, as an adhesion amount of C Ni deposition amount to the surface of the Ni plating layer 100-2000 mg / m ^2, it can be applied having a chemical conversion coating composed mainly of organic resin of 1 to 100 mg / m ^2. The amount of Ni deposited on the steel sheet before drawing and ironing is necessary to ensure the corrosion resistance after can body molding, particularly the corrosion resistance of the side wall of the can and the printability of the outer surface, and is 100 mg / m ^{2 to} 2000 mg / m. ² .

When the Ni adhesion amount on the steel sheet is less than 100 mg / m ² , depending on the degree of processing, the Ni adhesion amount on the can wall portion after the can body formation is insufficient, the ratio of Fe exposure increases, and the corrosion resistance of the inner surface of the can body decreases. In addition, the printability of the outer surface of the can also deteriorates.
On the other hand, even if the Ni adhesion amount on the steel plate exceeds 2000 mg / m ² , the inner surface corrosion resistance of the can and the outer surface printability of the can are not improved according to the adhesion amount, and the effect is saturated, so it is economical. Disadvantageous.

When the amount of metallic Cr in the steel sheet is less than 0.1 mg / m ² and the amount of hydrated Cr oxide (converted to metallic Cr) is less than 0.2 mg / m ² , the adhesion with the polyester film or the adhesion primer, especially after processing Adhesion is lowered, and corrosion under film tends to occur, which is a problem. If the amount of metallic Cr in the steel plate exceeds 15 mg / m ² , the effect of ensuring adhesion is saturated, which is economically undesirable. If the amount of hydrated Cr oxide (in terms of metallic Cr) is more than 30 mg / m ² , adhesion is reduced in the ironing process, and the polyester resin film may be peeled off, which is not preferable.

In the present invention, the Ni-plated steel sheet is a laminated steel sheet pre-coated with a polyester resin film from the viewpoint of formability at the time of drawing ironing and storage of contents when it becomes a can body and is filled with the contents. .
It is important that the thickness of the polyester resin film in the laminated steel sheet state is 8 to 50 μm on the steel sheet surface on the inner surface side of the can and 8 to 25 μm on the steel sheet surface on the outer surface side of the can.

  First, the reason for limiting the film thickness on the inner surface side of the can will be described. This is because if the thickness is less than 8 μm, the inner surface corrosion resistance of the can body may not be ensured due to the processing wrinkles at the time of can body molding. In addition, when the film is less than 8 μm, there is a problem that the workability of the lamination to the steel plate is greatly reduced. If it exceeds 50 μm, the effect is saturated from the viewpoint of corrosion resistance, the cost becomes disadvantageous, and a problem of defective punch missing in the molding process occurs, which is not preferable. Preferably, it is 15-30 micrometers.

Next, the reason why the film thickness on the outer surface side of the can is limited will be described. When the film is less than 8 μm, the workability of the lamination to the steel sheet is greatly reduced. If it exceeds 25 μm, galling is likely to occur, and the outer surface printability is deteriorated.
The polyester resin film laminated on the surface corresponding to the inner surface side of the steel plate can and the surface corresponding to the outer surface side of the can is a crystalline polyester resin having a melting point (Tm) of 230 ° C. or higher and a crystal melting heat (Hm). It is desirable that the cold crystallization heat (Hm) is 20 to 45 J / g, the glass transition temperature (Tg) is 60 ° C. or higher, and the intrinsic viscosity (IV) is 0.58 dl / g or higher.

By using a polyester resin having such characteristics, it is possible to follow the drawing ironing process at high speed and high workability, the inner surface side of the can has punch pull-out property, while the outer surface side of the can does not generate galling. Good moldability is ensured.
Examples of the crystalline polyester include polyethylene terephthalate, polybutylene terephthalate, polyethylene isophthalate, polyethylene naphthalate, and the like, and copolymers and blends thereof are also used.

  The copolymer component of the copolymerized 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 dicarboxylic acids such as cyclohexanedicarboxylic acid. Examples of the alcohol component include aliphatic glycols such as ethylene glycol, butanediol and hexanediol, and alicyclic polyols such as cyclohexanedimethanol. These can be used alone or in combination of two or more. In applications where the flavor of the contents is important, a copolymer polyester resin containing ethylene glycol, terephthalic acid, and isophthalic acid as main components is desirable.

  Moreover, since the polyester resin film used in the present invention needs to reduce elution of BADGE (bisphenol A diglycidyl ether) and BFDGE (bisphenol F diglycidyl ether), which are feared as endocrine disrupting substances in the contents, It is composed only of polyester and polyester raw materials, heat stabilizers, antioxidants and lubricants, and BADGE is 1 mg / kg or less and BFDGE is 1 mg / kg or less. The above-mentioned polyester resin film can be used as a single layer film or a multilayer film having two or more layers.

  The method for producing the polyester resin in the present invention is not particularly limited. That is, it can be used even if it is produced by either the transesterification method or the direct polymerization method. Moreover, in order to raise intrinsic viscosity (IV), what was manufactured by the solid phase polymerization method may be used. Furthermore, from the point of reducing the amount of oligomers eluted from the polyester resin in the retort sterilization treatment, pastro sterilization treatment, etc. carried out after filling and sealing the contents in the can, the oligomer content produced by the reduced pressure solid phase polymerization method is It is preferred to use a low polyester.

The density of the polyester resin film layer coated on at least the surface corresponding to the outer surface side of the can of the polyester resin film laminated steel sheet used in the present invention is 1.360 g / cm ³ or less. The galling of the outer surface film that occurs in the drawing and ironing process occurs because the reduction of the amorphous part (amorphous part) due to thermal crystallization increases the deformation resistance and consequently does not follow the processing.

In other words, this means that a film in which crystallization has occurred at the stage of the laminate is in a state where galling is likely to occur. In this sense, the density of the polyester resin film coated on at least the surface corresponding to the outer surface side of the steel plate used in the present invention is 1.360 g / cm ³ or less. A density of 1.360 g / cm ³ or less indicates that the coated film is in an amorphous state (amorphous state) or a state that is very close to an amorphous state. By setting it to 360 g / cm ³ or less, it becomes possible to ensure good galling resistance.

  In the present invention, the polyester resin film coated on the steel plate corresponding to the outer surface side of the can is coated on the metal plate via an adhesive primer containing a white pigment and / or a colored pigment. This is because of the color tone problem on the outer surface of the can when it becomes a can body. In particular, when steel is applied as a metal material as in the present invention, color tone, particularly whiteness, is an important requirement in terms of printed appearance on the outer surface of the can.

In the present invention, an adhesion primer containing a white pigment and / or a colored pigment is applied as means for ensuring the color tone of the outer surface of the can.
In the present invention, the resin applied to the adhesion primer is not particularly limited, but the main resin is a polyester resin, an epoxy resin, a polyester-epoxy copolymer resin, etc., and the curing agent is a melamine resin, an isocyanate resin, urea. Adhesive primers using one or more of resins, urethane resins, phenol resins and the like can be applied.

Of these adhesion primers, combinations of polyester resins and polyester-epoxy copolymer resins and melamine resins, isocyanate resins and the like as curing agents are suitable from the viewpoint of molding, particularly drawing and ironing.
In addition, when using a phenol resin as a curing agent, the phenol resin is a chromogenic resin and may change the color tone, so avoid using it alone and pay careful attention to the use and addition amount with other resins. There is a need.

The content of the white pigment and / or the colored pigment is 20 to 70% by mass in the adhesive primer. The content and thickness of the white pigment and / or colored pigment contained in the adhesive primer are factors that directly affect the concealment rate, and are therefore important from the viewpoint of securing the printed appearance. It is also a factor that leads to the destruction of the adhesive primer itself by processing.
When the content of the white pigment and / or the colored pigment is less than 20% by mass, the whiteness is insufficient and a beautiful printed appearance may not be obtained, which is not preferable.

  On the other hand, if the content of the white pigment and / or colored pigment exceeds 70% by mass, the resin content decreases, which causes a problem in terms of adhesion, and between the adhesion primer and the metal surface at the can wall by drawing and ironing. In the case of interfacial peeling or cohesive failure of the adhesive primer itself, this may be caused by molding at a high workability, which is not preferable. The thickness of the adhesion primer containing a white pigment and / or a colored pigment is 2 to 7 μm. If the thickness of the adhesive primer is less than 2 μm, even if the content of white pigment and / or colored pigment is large, as described above, white may be insufficient and a beautiful printed appearance may not be obtained. Absent.

On the other hand, if the thickness of the adhesive primer exceeds 7 μm, the adhesive primer on the can wall part may cause cohesive failure due to high-drawing and ironing processing and subsequent neck processing and flange processing, which is not preferable.
The pigment content in the adhesive primer, especially the white pigment content and the thickness of the adhesive primer, depends on the degree of processing of the can wall (thickness reduction rate) and, more specifically, the printing design of the outer surface and the color of the ink used. The required whiteness will vary, so it must be selected in practice.

  As white pigments and / or colored pigments to be included in the adhesion primer, white inorganic pigments such as fine particles of titanium oxide, fine particles of aluminum oxide, fine particles of calcium carbonate, fine particles of calcium sulfate, and colored pigments such as iron oxide can be applied. A desired color tone is obtained by combining one kind or several kinds. In addition, for example, when white is further required, it is possible to take measures such as interposing an ink such as white ink as a complementary color between an adhesive primer containing a polyester resin film and a white pigment and / or a colored pigment. Is possible.

When the ink is applied as a complementary color, since the processability of the ink layer is inferior, it is not preferable that the amount of adhesion is large because it causes cohesive failure in the ink layer and leads to poor adhesion, and the amount of adhesion is in the range of 1000 to 4000 mg / m ² . It is desirable to do. In this invention, the polyester resin film coat | covered by the steel plate equivalent to the inner surface side of a can also covers what is covered through the adhesion primer whose adhesion amount is 700-3000 mg / m < ² >.

  After filling and sealing the contents of the can body, when the can body is hit or impacted by dropping, etc., not only the metal material is deformed but also at the same time due to the impact, impact and deformation of the metal material In some cases, the coated resin film cracks or peels off when it is severe. The cracked part or peeled part of the film is the starting point of corrosion of the can body metal, and depending on the contents, the form of metal corrosion may become pitting corrosion and the can body may become a pitting can. .

  In the present invention, it is possible to apply the polyester resin film on the inner surface of the can directly to the steel plate for contents with weak corrosiveness. Is high, it is necessary to improve adhesion and to ensure impact resistance, so that the polyester resin film is coated through an adhesive primer.

  The adhesive primer applied to the surface corresponding to the inner surface side of the can is not particularly limited to the resin to be applied, but as a main ingredient, a resin such as polyester resin, epoxy resin, polyester-epoxy copolymer resin, and curing Adhesive primers using one or more of melamine resin, isocyanate resin, urea resin, urethane resin, phenol resin and the like as the agent can be applied.

Among these adhesive primers, epoxy resin, polyester-epoxy copolymer resin, etc. are the main ingredients, and combinations of phenolic resin, melamine resin, isocyanate resin, etc. as curing agents are small in adhesion loss due to processing, and are also resistant to resistance. Since impact properties are ensured, it is suitable from the standpoint of compatibility.
Adhesion amount of the adhesive primer in 700~3000mg / m ^2, the effect obtained by interposing a primer is less than 700 mg / m ^2, in particular not ensured in terms of impact resistance, whereas, adhesion and the 3000 mg / m ² greater The effect is saturated in both impact resistance.

As a method of coating the polyester resin film of the present invention on a steel sheet and making it amorphous, the film is supplied to a sufficiently heated steel sheet, the film is laminated with a laminating roll, and at the same time, the film is melted by the heat of the steel sheet and then rapidly cooled. Laminating in a one-step process or laminating in a two-step process in which a film is once supplied to a heated steel plate and primary bonded, followed by further heating the steel plate to melt the film and then rapidly cooling it. Etc. Whichever method is adopted, the density of the polyester resin film coated on the steel plate surface corresponding to at least the outer surface of the can needs to be 1.360 g / cm ³ or less. Is preferred.

  As an example, the adhesive primer is in contact with the metal plate on the metal plate that is the outer surface side of the steel plate can, and the adhesive primer containing a white pigment and / or a colored pigment is previously applied to a polyester resin film and dried. After coating the metal plate with a known method such as laminating the film on the inner surface side of the can using a laminating roll, or by sequentially coating the metal plate, etc., the primary bonding is continued. The laminated steel sheet is heated again as the plate temperature above the melting point of the polyester resin film or the melting point of the film supplied for the inner surface of the can, whichever is higher. Immediately after breaking, it is cooled rapidly with water cooling and / or air cooling to make the film amorphous, or a white pigment is previously applied to one side of the metal plate. Apply an adhesion primer containing colored pigment and / or colored pigment by roll coating or other methods, and after drying, raise the plate temperature, supply the polyester resin film, and simultaneously supply the inner surface film on the opposite side of the steel plate, laminating A method in which the inner and outer surfaces are simultaneously pressed with a roll to perform primary bonding, or the polyester resin film is first brought into contact with the adhesive primer and then pressed with a laminating roll, and then the inner film of the can is subsequently pressed and bonded with lamination. Then, after the primary adhesion is performed, the laminated steel sheet subjected to the primary adhesion can be heated and rapidly cooled to make the film amorphous by the same method as described above.

Even when the surface corresponding to the inner surface side of the can is coated with a polyester resin film via an adhesive primer, it can be performed according to the method of the outer surface described above. It goes without saying that which method is adopted is appropriately selected depending on the equipment owned.
Heating methods such as heating in an electric furnace, heating with hot air, heating in contact with a heating roll, induction heating at high frequency, etc. are used as the heating method for the metal plate during primary bonding. However, when heating a metal plate as a plate temperature to a temperature equal to or higher than the melting point of the polyester resin film to be performed subsequently or higher than the melting point of the polyester resin film coated on the surface corresponding to the inner surface of the can, the polyester resin Since the film is coated, non-contact heating such as a method of heating in an electric furnace, a method of heating with hot air, a method of induction heating at high frequency, etc. is preferable, and it is better not to use a contact type heating method such as a heating roll. Needless to say. In addition, as a method of rapid cooling, it is possible to adopt a method of cooling by blowing compressed air or cooled compressed air, or a method of cooling by immersing in water or the like alone or in combination.

In order to reduce the density of the polyester resin film of the present invention to 1.360 g / cm ³ or less, after the primary adhesion, the melting point of the polyester resin film or the melting point of the inner surface film coated on the other surface is continued. If the plate temperature of the metal plate is raised above the higher melting point of any one of the above, and the supplied film is a biaxially stretched film or a uniaxially stretched film, it is sufficiently melted to break the crystal, It is important not to cause crystallization during the cooling process. In particular, the rapid cooling condition described above is important, and it is important that the heat transfer coefficient on the surface of the polyester resin film is cooled under the condition of 0.0005 cal / cm ² · sec · ° C. As a method of rapid cooling, it is possible to employ a method of cooling by blowing compressed air or cooled compressed air, or a method of cooling by immersing in water or the like alone or in combination.

Next, the can body of the present invention will be described.
The can body of the present invention is a can body obtained by drawing and ironing the above-mentioned polyester resin film laminated steel sheet, and the thickness of the resin film on the side wall portion of the inner surface of the can is 5 to 30 μm. The peel strength of the polyester resin coating is 500 g / cm or more, the exposure rate of Fe under the polyester resin coating on the inner surface of the can is less than 50%, and the average Ni coating amount on the side walls of the inner and outer surfaces of the can is 50 to It is a drawn and ironed can excellent in inner surface corrosion resistance and outer surface printability of 700 mg / m ² .

If the average Ni coating amount on the side wall of the can is less than 50 mg / m ² , filling with highly corrosive contents may be insufficient in terms of corrosion resistance, which is not preferable.
On the other hand, if the average Ni coating amount on the side wall portion of the can exceeds 700 mg / m ² , the corrosion resistance is almost saturated, which is disadvantageous in terms of cost. Further, regarding the outer surface side of the can, when the average Ni coating amount is less than 50 mg / m ² , the high spectral reflectance of Ni metal is not sufficiently exhibited, and the low spectral reflectance of Fe is emphasized. Therefore, the application effect of the adhesive primer containing the white pigment and / or the colored pigment described above is reduced, and it may be difficult to ensure good printability.

On the other hand, when the average Ni coating amount on the side wall of the can body exceeds 700 mg / m ² , the effect of Ni for ensuring good printability approaches saturation, which is disadvantageous in terms of cost.
Needless to say, the printability of the outer surface is related to the content of the white pigment and / or the colored pigment in the adhesive primer, the thickness of the adhesive primer, and the degree of processing of the can wall portion (plate thickness reduction rate). . The average Ni coating amount in the side wall portion of the can body is preferably in the range of 100 to 700 mg / m ² from the viewpoint of ensuring corrosion resistance on the inner surface of the can and ensuring printability on the outer surface of the can.

When a plated steel sheet coated with a thermoplastic resin film such as the polyester resin film of the present invention is drawn and ironed, the plating layer is not directly in contact with the forming tool, but the plating layer and the chemical conversion treatment layer on the surface thereof are also present. Affected, the thickness becomes thinner.
The same applies to the Ni-plated steel sheet of the present invention, and depending on the amount of plating deposited in the steel sheet state and the processing conditions, the iron exposure rate of the side wall of the can after forming may be particularly large. If the exposure rate of iron becomes too large, the inner surface of the can causes a decrease in corrosion resistance, and the outer surface of the can causes a decrease in printability.

In this invention, the exposure rate of iron in the side wall part of the inner surface of a can shall be less than 50%. If the exposure rate of iron exceeds 50%, corrosion under film tends to occur, which may be a problem in practice and is not preferable.
The iron exposure rate was measured by Auger spectroscopic analysis (acceleration voltage: 10 Kv, sample current: 5 × 10E-7A, beam diameter 100 μm) after removing the polyester resin film coating on the inner surface of the can body. Measurement was performed, and the exposure rate of iron was calculated from the detected element ratio.

  It is important that the minimum thickness of the polyester resin film in the side wall of the can is 5 to 30 μm. If the minimum thickness is less than 5 μm, defects may be caused from the viewpoint of corrosion resistance, which is not preferable. On the other hand, if the minimum thickness exceeds 30 μm, the effect is saturated in terms of corrosion resistance, which is disadvantageous in terms of cost, and problems such as defective punching in the can body forming process occur, which is not preferable.

  Further, it is important that the peel strength of the polyester resin film in the side wall portion on the inner surface of the can is 500 g / cm or more. When the peel strength is less than 500 g / cm, corrosion under a film is likely to occur, and it cannot be put to practical use. The peel strength is more preferably 900 g / cm or more. The peel strength is measured by squeezing and ironing, heating at a temperature equal to or higher than the higher melting point of the polyester resin film coated on the inner and outer surfaces of the can and then rapidly cooling.

  The peel strength was measured by the method described in Patent Document 8 (Japanese Patent Laid-Open No. 8-50091). A test piece was cut out from the can body in the can height direction, and three types of laminated steel sheets having different thicknesses were prepared by anodizing the steel sheet side of the laminated steel sheet, cut into a width of 10 mm and a length of 100 mm, and a thickness of 5 mm. Bonded to steel plate. The adhesive used was XA-1189-2 (main agent) / H2601 (curing agent), Tg = 130 ° C .: manufactured by Shikoku Kasei Kogyo Co., Ltd. and Bond Silex 100 (registered trademark) (Tg = −60 ° C.): Konishi Co., Ltd. was blended at a mass ratio of 1: 1, and the curing conditions were one day at room temperature. Tg after curing of the adhesive is 30 ° C., and the thickness is 1000 μm.

  In this test piece, when a cut reaching the steel plate is made in the laminate coating of the polyester resin film laminated steel plate and bent around the cut portion, the laminate coating and the steel plate are separated. This knob portion is sandwiched between upper chucks of a tensile tester, and a support plate (steel plate having a thickness of 5 mm) is sandwiched between lower chucks, and pulled and peeled at 180 m in a direction of 20 m / min. From the obtained thickness and tensile strength of the test values, the extrapolated value when the thickness was set to [0.000 mm] was defined as the peel strength in the present invention. The method of extrapolating to the plate thickness [0.000 mm] is to obtain a y-intercept of the regression equation by linear regression of the tensile strength at each plate thickness and the square of each plate thickness.

Finally, a method for producing the can of the present invention will be described.
In the present invention, a can body obtained by drawing and ironing the above-mentioned polyester resin film laminated steel sheet is heated to a temperature equal to or higher than the melting point of the polyester resin film and then rapidly cooled, and at least the density of the polyester resin film coated on the inner surface side of the can is set to 1. It is a manufacturing method of a squeezing and ironing can excellent in inner surface corrosion resistance and outer surface printability, characterized by being 360 g / cm ³ or less. The above-mentioned polyester resin film laminated steel sheet is drawn and ironed, then heated to the melting point of the polyester resin film or higher and then rapidly cooled to make the density of the polyester resin film 1.360 g / cm ³ or less.

  The drawing and ironing process causes processing distortion in the polyester resin film and lowers the adhesion. If the polyester resin film has poor adhesion, under-film corrosion will occur, or if there is a pinhole in the film, corrosion will occur from that part, and it will spread greatly under the film, resulting in film peeling. Problems are likely to occur. In particular, the film peeling tends to be said that the larger the processing strain in the polyester resin film, the more severe the film peeling.

In the method of the present invention, in order to avoid such problems as much as possible, after the polyester resin film laminated steel sheet is drawn and ironed, it is heated to a temperature higher than the melting point of the polyester resin film and then rapidly cooled, and the density of the polyester resin film is 1.360 g / cm. ³ or less, but the density is 1.360 g / cm ³ or less as described above, because the coated film is in an amorphous state or an extremely amorphous state. Almost no strain remains and the adhesion can be sufficiently recovered.

As a method of heating the polyester resin film of the drawn and ironed can and then rapidly cooling it to a density of 1.360 g / cm ³ or less, the temperature of the can body can be set in an electric furnace, a hot air furnace or a high frequency. A method may be employed in which the temperature is raised to a temperature equal to or higher than the melting point of the polyester resin film, the polyester resin film is once melted, and then cooled by blowing compressed air or cooled compressed air.

Hereinafter, the effects of the method of the present invention will be specifically described with reference to Examples, but the present invention is not limited thereto. In addition, the shaping | molding method and evaluation method performed in the present Example are as follows. (1) The film thickness was measured at 10 points with 10 micrometers at arbitrary points, and the average value was calculated.
(2) The adhesion amount of the ink layer and the primer layer was dissolved in a solvent and determined from a mass difference.
(3) The density of the polyester resin film was measured by a density gradient tube method.

(4) Drawing and ironing can molding is blanked to a blank diameter of 142 mm, a cup is molded with a first drawing ratio of 1.6, then redrawed with a 2nd drawing ratio of 1.3, and ironing is performed in three steps, and the diameter of the can body A 65.8 mm drawn and squeezed cup was formed. The molding speed of redrawing and 3-step ironing was 100 cpm, and 150 cans were molded. The total ironing rate was three conditions of 30, 45, and 66.7%. The molded can was evaluated for the presence or absence of galling, the presence or absence of film peeling, and the punching ability during molding.

(5) Measurement of can inner surface average Ni coating thickness and can inner surface average organic resin coating thickness Can inner surface average Ni coating thickness peels organic resin on inner surface of can wall part (30-80 mm part from can bottom) where ironing is the largest Then, three 20 mmφ circular specimens were prepared, measured by the fluorescent X-ray method, and the average value was calculated. The inner surface average organic resin film thickness was obtained by dissolving the metal at the same site and peeling off the organic resin, measuring 10 points at 10 points with respect to arbitrary points, and calculating the average value.

(6) The method for measuring the exposure rate of iron is to perform measurement by Auger spectroscopic analysis (acceleration voltage: 10 kv, sample current: 5 × 10E-7A, beam diameter 100 μm) after removing the laminated film film on the inner surface of the can body, The exposure of Fe was calculated from the detected element ratio.
(7) In the laminating property, it was judged whether or not the film could be laminated without any problem in the laminating operation at a line speed of 150 m / min.

(8) The inner surface corrosion resistance was evaluated by an actual can storage test. In the actual can storage test, 100 cans were filled with Coca-Colalite (registered trademark) (carbonated beverage), the lid was wrapped, and then stored at 37 ° C for 6 months, then opened, and under the inner surface of the can The occurrence area of the corroded portion was measured and judged as good or bad.
(9) External surface printability evaluation evaluated external galling (smoothness). Furthermore, only when the ink layer was white, the appearance and color tone (L value) of the can body were measured to determine whether the ink was good or defective. .
Good: No color spots and practicality when L * value of can body part is 75 or more Poor: There is color spots or L * value of can body part is 75 or less and is not practical

Invention Example No. 1 in Table 1 As shown in FIG. 1, a base material having a thickness of 0.23 mm (HR30T) 57 is plated with Ni of 500 mg / m ² , and further treated with electrolytic chromic acid to give 2 mg / m ^{2 of} metal Cr, hydrated Cr oxide ( 6 mg / m < ² > was deposited as (Cr equivalent). The Ni-plated steel sheet was heated to 235 ° C. (melting point of film + 5 ° C.) with a heating roll (jacket roll), and 1300 mg / m ^{2 of an} epoxy primer was previously applied to the inner surface of the can body. the polymerization PET film, 2000 mg / m ² of the ink layer previously TiO ₂ on the side serving as the outer surface of the can body and pigment, then a 10 mol% of isophthalic acid copolymerized PET film of 12μm with a polyester primer 12500mg / m ² was applied After primary adhesion to both surfaces by a thermocompression bonding method with a laminating roll, the steel plate was subsequently heated to a plate temperature of 260 ° C. (melting point of film + 30 ° C.), and then rapidly cooled to prepare a laminated steel plate. The prepared laminated steel sheet was formed under the drawing and ironing conditions described below. The total ironing amount was 66.7%. The molded can body was passed through a heating furnace and heated to a can body temperature of 260 ° C. (melting point of film + 30 ° C.), and then rapidly cooled with compressed air.

(Invention Examples No. 2 to 5, Comparative Example Nos. 6 to 13)
Invention Example No. In the same manner as in No. 1, steel plates were prepared by laminating films on both sides of the Ni-plated steel plate shown in Table 1, and can body molding and heat treatment (melting point of film + 30 ° C.) were similarly performed.
(Comparative Example No. 14)
Invention Example No. In the same manner as in No. 1, a steel plate in which films were laminated on both surfaces of a Ni-plated steel plate shown in Table 1 was prepared, and can body molding and heat treatment (melting point of the film −10 ° C.) were similarly performed.

As described above, according to the present invention, a squeezed iron can having good inner surface corrosion resistance and good outer surface printability can be obtained. In addition, stable production is possible.


Patent applicant: Nippon Steel Corporation and 1 other
Attorney Attorney Shiina and others 1

Claims (4)

In drawing and ironing steel cans having thermoplastic resin film layer on both surfaces of the steel sheet, Ni-plated layer of adhesion amount on the surface of the steel sheet is 100-2000 mg / m ^2, and the metal Cr of 0.1 to 15 mg / m ² on its surface A polyester resin film having a thickness of 8 to 25 μm is formed on the surface corresponding to the inner surface side of the can of the Ni-plated steel sheet having a chromate film layer made of hydrated Cr of 0.2 to 30 mg / m ^{2 in} terms of metal Cr. On the surface corresponding to the outer surface side of the can, a polyester resin film having a thickness of 8 to 25 μm is laminated via an adhesive primer layer having a thickness of 2 to 7 μm containing 20 to 70% by weight of white and / or colored pigment. and polyester density of the resin film is Ri 1.360g / cm ³ der below is laminated on the surface corresponding to the outer surface side of the surface and the can corresponding to the inner surface of the can as the outer surface of the can The polyester resin film is a crystalline polyester resin having a melting point (Tm) of 230 ° C. or higher, a crystal melting heat (Hm) and / or a cold crystallization heat (Hm) of 20 to 45 J / g, and a glass transition temperature ( A polyester resin film-laminated steel sheet for a drawn and ironed can excellent in inner surface corrosion resistance and outer surface printability, wherein Tg) is 60 ° C. or higher and intrinsic viscosity (IV) is 0.58 dl / g or higher . 2. The polyester resin film having a thickness of 8 to 50 μm is laminated on the steel plate surface which is the inner surface side of the can through an adhesive primer layer having an adhesion amount of 700 to 3000 mg / m ^2. A polyester resin film laminated steel sheet for a drawn and ironed can having excellent inner surface corrosion resistance and outer surface printability. It is a can formed by forming the polyester resin film laminated steel sheet according to claim 1 or 2, wherein the minimum thickness of the polyester resin film in the side wall portion on the inner surface side of the can is 5 to 30 µm, and the polyester resin in the side wall portion. The peel strength of the film coating is 500 g / cm, and the exposure rate of Fe under the polyester resin film layer in at least the side wall portion on the inner surface side of the can is less than 50%, and the average in the side wall portion on the inner and outer surfaces of the can A drawn and ironed can excellent in inner surface corrosion resistance and outer surface printability, wherein the Ni coating amount is 50 to 700 mg / m ² . The polyester resin film-laminated steel sheet according to claim 1 or 2 is drawn and ironed, heated at a temperature equal to or higher than the higher melting point of the polyester resin film coated on the inner and outer surfaces of the can, and then rapidly cooled to at least the inner surface of the can. A method for producing a squeezed iron can having excellent inner surface corrosion resistance and outer surface printability, wherein the density of the polyester resin film coated on the side is 1.360 g / cm ³ or less.