JP2000202945A - Film laminated steel panel for two-piece can excellent in processing adhesion and corrosion resistance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the deterioration of adhesion after processing and corrosion resistance of a can body excellent in adhesion and corrosion resistance and receiving severe processing after film lamination to make the can body adaptable to all of contents. SOLUTION: This laminated steel panel is equipped with a steel panel, the electrolytic chromate treatment layer formed on at least one surface of the steel panel and consisting of a lower layer being a metal chromium layer with a chromium adhesion amt. per a single surface of 30 mg/m2 or more and an upper layer being a hydrated chromium oxide layer with a chromium oxide adhesion amt. per a single surface of 5-30 mg/m2 in terms of chromium, the first resin layer formed on the electrolytic chromate treatment layer and based on a polyester resin and a phenol and/or cresol/resole type phenol resin and the second thermoplasric resin film layer formed on the first resin layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film-laminated steel sheet having excellent adhesion and corrosion resistance after processing, and more particularly to a two-piece film-laminated steel sheet subjected to severe processing after film lamination.

[0002]

2. Description of the Related Art In a conventional can-making process, a metal plate such as a tin plate, an electrolytic chromate-treated steel plate (hereinafter, referred to as TFS), aluminum or the like is coated once or a plurality of times, and then a can-making process is performed. In some cases, painting may be performed after can processing.

In recent years, a technique for laminating an organic resin film on a metal plate has been developed and put into practical use. JP-A-57-182428, JP-B-61-3676.
Japanese Patent Application Laid-Open Publication No. H11-133, etc. discloses a method in which a metal plate is heated to a temperature equal to or higher than the melting point of a film and bonded by heat fusion.

[0004] There are various methods for processing after film lamination. Particularly, the processing with a high degree of processing is performed alone or in combination with processing such as drawing, ironing, pulling and bending on a metal plate. There is a two-piece can manufacturing method in which a can bottom and a can copper part are integrally formed by repeatedly applying.

On the other hand, in recent years, can manufacturers have been reducing the thickness of can bodies from the viewpoint of material saving.
In the case of piece cans, measures are taken to increase the degree of processing during can making.

By the way, severe processing performed after film lamination has a great effect on the form of the plating film of the base surface-treated steel sheet. For example, in the case of TFS, when the plating film is observed by dissolving and removing the film from the material after the draw bead processing, a number of cracks are generated in the metal chromium layer and the hydrated chromium oxide layer, and a new surface of metal chromium and iron appears. There was found. In other words, since the outermost organic resin film has a large ductility, it shows a sound appearance even when subjected to quite severe processing, but the electrolytic chromate film, which is an extremely thin film compared to the organic resin film and the base steel sheet, has a particular effect. It is thought that cracks occur when the base steel sheet is deformed while causing slippage due to a new surface at the interface.

[0007] Since the adhesion between the organic resin film and the base surface-treated steel sheet depends on the state of adhesion at the interface between the organic resin film and the electrolytic chromate-treated film, cracks occur in the electrolytic chromate-treated film and the sound bonding interface decreases. By doing, the adhesion after processing (hereinafter referred to as processing adhesion)
And the corrosion resistance deteriorates.

As described above, if the working degree is increased in order to reduce the wall thickness for the purpose of saving the material, the performance such as working adhesion and corrosion resistance is greatly deteriorated. The same applies to the case where the above-mentioned film bonding method by heat fusion is used, and the work adhesion and the work corrosion resistance are greatly deteriorated and are hardly practical.

As a technique for solving such a problem, a method of laminating an organic resin film coated in advance with a polymer composition containing an epoxy resin and a curing agent thereof on a metal plate is disclosed in JP-B-63-13829. , Japanese Patent Laid-Open No. 1-2
No. 49331, Japanese Patent Publication No. 4-74176, Japanese Patent Publication No. 5-71035, Japanese Patent Application Laid-Open No. 2-70430, and the like. Also, a method of applying an epoxy-phenol-based, epoxy-urea-based, urethane-based adhesive primer to one or both surfaces of a steel sheet is disclosed in Japanese Patent Application Laid-Open No. Hei 4-3
No. 44231.

According to these methods, the processing adhesion and the corrosion resistance are improved to some extent, but the content of a corrosive beverage such as an acidic beverage is inferior to that of a painted can or the like and cannot be said to be sufficient from the viewpoint of corrosion resistance.

Further, when particularly severe processing is performed in the manufacturing process, further processing adhesion and corrosion resistance are required,
When impact such as dents is given to the can from the outside, the degree of performance degradation is further increased, so improvement of processing adhesion and corrosion resistance by these technologies is not enough,
There is a problem that it cannot be applied to some contents.

[0012]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and suppresses the deterioration of processing adhesion and corrosion resistance of a can body subjected to severe processing after film lamination. An object of the present invention is to provide a two-piece can film-laminated steel sheet applicable to contents.

[0013]

Means for Solving the Problems In order to achieve the above object, the present inventors have developed a surface-treated steel sheet having relatively good adhesion to a conventional organic resin film made of a thermoplastic resin such as a laminate film. Using TFS as a base, the bonding mechanism at the bonding interface between the organic resin film and TFS was examined in detail. The present inventors further investigated in detail the bonding interface when subjected to severe processing after bonding with the conventional organic resin film, and found that the inner environment after filling the contents or the high-temperature steam environment at the time of retort treatment. , The mechanism by which the processing adhesion and the corrosion resistance deteriorate was also investigated in detail.

As a result of investigating the bonding mechanism, it was found that hydrogen bonding is a dominant factor in bonding between the resin film and the TFS interface. Since the adhesive force is based on hydrogen bonding, it is not so high as compared with that based on covalent bonding.

If the adhesiveness is insufficient, the resin film is displaced by high working, and the film may be broken, and when the metal portion is exposed, the corrosion resistance is deteriorated.

Further, as a result of investigating the mechanism by which the processing adhesion and the corrosion resistance are deteriorated, it was found that severe processing performed after film lamination has a great effect on the form of the plating film on the base surface-treated steel sheet. For example, in the case of TFS, it was found that the chromium metal layer and the hydrated chromium oxide layer frequently cracked, and a new surface of chromium metal and iron appeared. In other words, since the outermost organic resin film has a large ductility, it shows a sound appearance even when subjected to quite severe processing, but the electrolytic chromate treated film, which is an extremely thin film compared to the organic resin film and the base steel sheet, is particularly affected. It is considered that the base steel sheet is susceptible to cracks and cracks occur when the base steel sheet slips and deforms while forming a new surface at the interface.

Since the adhesion between the organic resin film and the base surface-treated steel sheet depends on the adhesion state at the interface between the organic resin film and the electrolytic chromate-treated film, cracks occur in the electrolytic chromate-treated film and the sound bonding interface decreases. By doing so, the adhesion after processing deteriorates. In addition, the deterioration of the adhesion may cause the film to break, and also deteriorates the corrosion resistance.

Further, in an aqueous environment of the inner surface after filling the contents or in a high-temperature steam environment during the retort treatment, water molecules permeating the resin film attack the film / TFS interface. Deterioration can be accelerated.

The mechanism by which the processing adhesion and the corrosion resistance are degraded has been described above. Based on such knowledge, the present inventors have found that an organic resin layer, which has not been conventionally available, is introduced in order to suppress this degradation. That is, on the interface between the conventional resin film and TFS, the adhesion at the interface is improved,
In addition, an organic resin layer (hereinafter, also referred to as a first resin layer) that prevents exposure of metal and elution of metal ions without breakage due to high working is interposed.

In order to improve the adhesion at both interfaces between the conventional outermost resin film (hereinafter, also referred to as a second resin film layer) and TFS by inserting the first resin layer, it is necessary to use TFS and TFS. It is necessary that the adhesion of the first resin layer to each of the second resin film layers is excellent and that the material itself does not cause cohesive failure.

In order to prevent cohesive failure, it is preferable that the organic component forming the first resin layer is a high molecular weight substance to some extent. In addition, it is considered that it is preferable to improve the hydrogen bond with TFS or to cause a covalent bond or a coordination bond to be excellent in adhesion to TFS. It is preferable to introduce a polar group such as a hydroxyl group or a carboxyl group in order to improve the hydrogen bond, and it is preferable to introduce a hydroxyl group or a carboxyl group in order to form a coordination bond.

Further, in order to enhance the adhesion to the second resin film layer, it is considered preferable to improve the secondary bonding force by increasing the compatibility with the resin film. For example, when the second resin film layer is a polyester-based resin, it is effective to introduce an aromatic ring or the like into the organic component forming the first resin layer to bring the solubility parameter closer to that of the polyester-based resin.

In order to prevent the metal from being exposed without breaking the first resin layer due to the high working, it is necessary to withstand the elongation at the time of the high working and to cover the electrolytic chromate treatment film. It is necessary that the organic substance forming the first resin layer is a high molecular weight substance and has a flexible skeleton. In addition to covering, the material itself needs to have corrosion resistance, and for that purpose, the organic substance needs to have a rigid skeleton such as an aromatic ring.

In order to prevent metal ions from being eluted, it is desirable to introduce a hydroxyl group, a carboxyl group, etc., which may form a coordination bond with the metal ions.

To summarize the above, the organic material forming the first resin layer has a rigid structure (for example, an aromatic ring).
And a flexible structure, and a polar group such as a hydroxyl group or a carboxyl group needs to be introduced.

Based on such findings, the present inventors:
Regardless of the conventional method of applying an organic solvent-based adhesive to a film or steel sheet during lamination, TFS
Specific aqueous organic or organic solvent organic substances in the hydrated chromium oxide layer of the chromium oxide layer, preferably from the viewpoint of environmental issues, by applying aqueous organic substances, processing adhesion after subjecting the steel sheet after film lamination to strict processing It has been found that the properties and corrosion resistance are significantly improved.

That is, according to the present invention, a steel plate is formed on at least one surface of the steel plate, and the lower layer is formed on a surface of the steel plate at a ratio of 3 per side.
A metallic chromium layer having a 0 mg / m ² or more adhesion amount, an electrolytic chromate treatment layer of hydrated chromium oxide layer upper layer having a deposition amount of 5 to 30 mg / m ² on one surface per reckoned as metal chromium, the electrolytic chromating A first resin layer formed on the treatment layer and mainly containing a polyester-based resin and a phenolic and / or cresol-based resol-type phenol resin; and a second thermoplastic layer formed on the first resin layer. A film-laminated steel sheet for a two-piece can excellent in processing adhesion and corrosion resistance, comprising a resin film layer.

In the present invention, the average adhesion amount of the first resin layer is 50 to 10000 m as a solid concentration.
g / m ² , and the main components of the resin composition are a number average molecular weight of 3,000 to 30,000, a hydroxyl value of 5 to 30, and an acid value of 0 to 0.
50, preferably 60 to 99 parts by weight of a polyester resin having a glass transition temperature of 5 to 110 ° C. and 1 to 40 parts by weight of phenolic and / or cresol resole phenolic resin.

In the present invention, the thermoplastic second resin film layer is preferably a polyester resin film layer having a thickness of 10 μm or more.

According to the present invention having such a configuration,
Suppresses deterioration of work adhesion and corrosion resistance due to increase in workability due to thinning of can bodies, which is being promoted from the viewpoint of resource saving, and can be applied to contents that require retort treatment etc., which is a high temperature steam environment. The film-laminated steel sheet for two-piece cans can be provided without increasing the cost.

[0031]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

The film-laminated steel sheet for two-piece cans according to the present invention is formed on at least one surface of a base steel plate, and the lower layer is a metal chromium layer having an adhesion amount of 30 mg / m ² or more per side, and the upper layer is one side. An electrolytic chromate treatment layer of a hydrated chromium oxide layer having an adhesion amount of 5 to 30 mg / m ^{2 in} terms of metal chromium per metal chromium oxide, and a polyester-based resin, phenolic acid and / or
Alternatively, it includes a first resin layer mainly composed of a cresol-based resol-type phenol resin, and a thermoplastic second resin film layer formed on the first resin layer.

In the present invention, the base steel sheet is not particularly limited, and any steel sheet usually used for this type of surface-treated steel sheet can be used. For example, ordinary low-carbon cold-rolled steel sheet having a thickness of 0.1 to 0.3 mm, low-carbon A
1 Killed steel plate or the like is used.

On at least one surface of such a base steel sheet, as a surface treatment film directly or after chromium plating,
A two-layer electrolytic chromate treatment film is formed in which the lower layer is a metal chromium layer and the upper layer is a hydrated chromium oxide layer. As the electrolytic chromate treatment method at this time, a commonly used known method can be adopted, a one-liquid method for simultaneously depositing chromium metal and hydrated chromium oxide, and hydrated chromium oxide after forming the chromium metal layer. May be any of the two-component methods for precipitating the compound.

[0035] Here, the underlying metallic chromium coating weight is preferably although per side 30 mg / m ² or more, more preferably 30 to 300 mg / m ^2. The amount of adhesion is 3
If it is less than 0 mg / m ² , a problem occurs in corrosion resistance. 3
If it exceeds 00 mg / m ² , the performance is not inferior at all, but it is not preferable from an economic viewpoint. In any case, there is no problem as long as the amount is used for a normal electrolytic chromate-treated steel sheet.

The adhesion amount of the hydrated chromium oxide in the upper layer is preferably
Or 5-30 mg / m in terms of metal chromium per side^Two 
It is. 5mg / m^Two Less than metal chrome
Layer is not uniformly covered by hydrated chromium oxide
Exposed area becomes large, corrosion resistance and aging resistance, processing
It is not preferable because the adhesion is poor. In addition, 30mg / m ^Two 
If it exceeds, the hydrated chromium oxide layer is too thick
Cause deterioration of appearance and adhesion
Not good.

A first resin layer made of a resin composition containing a polyester resin and a phenolic resin and / or a cresol resol type phenol resin is formed on the electrolytic chromate treatment film. These resin compositions can be obtained in either an organic solvent-based or water-based form, and both forms can be used in the present invention.

As the polyester resin, succinic acid,
Dibasic such as maleic acid, fumaric acid, phthalic acid, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, adipic acid, sebacic acid, succinic acid, azelaic acid, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid Polybasic acids such as acid, trimellitic acid, and pyromellitic acid, and ethylene glycol, 1,2-propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, and neopentyl glycol Is directly condensed with a diol such as 1,4-cyclohexanedimethanol, diethylene glycol, triethylene glycol and polyethylene glycol, and a polyhydric alcohol such as glycerin and pentaerythritol in the absence of a catalyst or a catalyst such as dibutyltin oxide or titanium tetrabutoxide. Chain And / or it may be used branched ones. Monobasic acids such as acetic acid, benzoic acid, 4,4-bis (4'-hydroxyphenyl) pentanoic acid, and monohydric alcohols such as cetyl alcohol, decyl alcohol and lauryl alcohol for the purpose of controlling the molecular weight of the resulting resin Can also be used as appropriate. Further, in order to lower the melting point of the material and promote a smooth condensation reaction, isophthalic acid, terephthalic acid and the like can be used as an ester such as dimethyl ester and diethyl ester.

The polyester resin obtained in this manner is converted into an aromatic solvent such as toluene and xylene, an alcohol solvent such as methanol, ethanol, isopropanol and n-butanol, acetone, methyl ethyl ketone and the like.
Known organic solvents such as ketone solvents such as methyl isobutyl ketone, isophorone and cyclohexanone; ether alcohol solvents such as methyl cellosolve, ethyl cellosolve and butyl cellosolve; ether ester solvents such as methyl cellosolve acetate, ethyl cellosolve acetate and butyl cellosolve acetate; Dissolve and use.
In another embodiment, a polyester resin dissolved in a small amount of a water-affinity organic solvent is dropped into 40 to 80 ° C. warm water containing an amine such as ammonia, triethylamine, or dimethylethanolamine under pressure to disperse in water. A body can also be used. Examples of the water-compatible organic solvent include alcohol solvents such as methanol, ethanol, isopropanol and n-butanol, ketone solvents such as acetone and methyl ethyl ketone, and ether alcohol solvents such as methyl cellosolve, ethyl cellosolve and butyl cellosolve. .

The first resin layer of the present invention is formed of a resin composition containing the above-mentioned polyester resin and phenolic and / or cresol resol type phenol resin as main components.

Examples of phenolic and / or cresol-based resole type phenolic resins include phenolic carbonate, o-cresol, m
-Use a product obtained by condensing cresol, p-cresol or a mixture thereof with an alkali such as ammonia, triethylamine, caustic soda, caustic potash, or the like, or subjecting this to alkyl etherification with an alcohol such as methanol, ethanol, or n-butanol. can do.

The phenolic and / or cresol-based resol-type phenolic resin may be simply mixed with the polyester-based resin as it is, but a phenolic and / or cresol-based resol-type phenolic resin which has been reacted in advance to such an extent that it does not gelate is used. May be.

The resin composition containing the polyester resin and the phenolic and / or cresol resole type phenol resin may be further added with a cured product such as an amino resin such as a melamine resin or a urea resin or a block urethane resin, if necessary. Epoxy resins, urethane resins, other polyester resins, novolak-type phenol resins and the like can also be blended. Further, if necessary, a rust preventive such as strontium chromate, calcium chromate, zinc chromate, calcium silicate, aluminum tripolyphosphate or the like can be blended in order to increase the corrosion resistance.

The thus obtained resin composition containing the polyester resin and the phenolic and / or cresol-based resol-type phenol resin as main components is formed on the above-mentioned electrolytic chromate-treated film as a first resin layer. As a forming method, there is a method of forming a first resin layer on a steel sheet in advance or a method of forming a first resin layer on a side surface of a steel sheet of a thermoplastic second resin film layer in advance. Methods can also be used.

As the coating method, a known method which is usually used in any case can be adopted, for example, a roll coating method, a curtain flow method, a die coater method, an immersion method, a spray coating method, a curtain coating method, and the like. Examples of the method include a flow coat method, an ironing method, a blade coater method, a rod coater method, an air doctor coater method, and a kiss coater method.

As a drying method, when a steel sheet is coated, either a jacket roll method or a method using a drying oven may be used, and the drying can be performed by a known method. Examples of the drying oven include a hot air oven, an infrared oven, and an induction furnace. A heating furnace or the like can be used. The drying temperature is 100 ~
270 ° C, 50 when applied to thermoplastic resin film
It is desirable to perform the heat treatment at a temperature equal to or lower than the heat resistance temperature of the resin film of about 110 ° C. The drying temperature is preferably 2 seconds to 2 minutes in each case.

The preferable adhesion amount of the first resin layer is 50 to 10000 mg / m ² as a solid concentration, and the preferable composition of the resin composition is polyester resin 60
-99 parts and 1-40 parts of phenolic and / or cresol-based resole phenolic resin.

When the amount of adhesion is 50 mg /
If it is less than ² m ² , a sufficient degree of coverage cannot be obtained, so that the corrosion resistance is reduced. If it exceeds 10,000 mg / m ² , cohesive failure tends to occur inside the first resin layer, and as a result
Workability and corrosion resistance tend to decrease.

When the amount of the polyester resin is less than 60 parts by weight, the processing adhesion and the corrosion resistance decrease, and when the amount exceeds 99 parts by weight, the corrosion resistance decreases.

In the present invention, the polyester resin in the resin composition preferably has a number average molecular weight of 3,000.
-30,000 (according to GPC), hydroxyl value 5-30, acid value 0-50, glass transition temperature 5-110 ° C.

The number average molecular weight of the solvent-based or aqueous polyester resin is desirably 3,000 to 30,000. When the number average molecular weight is less than 3000, processability,
If the adhesion is lower than 30,000, the solid content is reduced to maintain the coating viscosity, and there is no improvement in adhesion or the like.

The hydroxyl value is preferably from 5 to 30. When the hydroxyl value is less than 5, the crosslink density is insufficient, and it is not possible to withstand high-strength processing, and the processability and adhesion are reduced. When the hydroxyl value exceeds 30, the corrosion resistance decreases.

The glass transition temperature is preferably from 5 to 110 ° C. If the glass transition temperature is less than 5 ° C., the corrosion resistance is reduced, and 1
If the temperature exceeds 10 ° C., the processability and the adhesion will decrease.

The desired range of the acid value differs between the solvent type and the aqueous type. In the case of the solvent type, it is preferably 50 or less. If it exceeds 50, the corrosion resistance decreases. In the case of aqueous, 5 to 50 is desirable.
If it is less than 5, the water dispersibility will be insufficient, and if it exceeds 50, the corrosion resistance will decrease.

In the laminated steel sheet of the present invention, a thermoplastic second resin film layer is laminated on the first resin layer from the viewpoint of corrosion resistance and the like. Examples of the thermoplastic resin film include polyesters such as polyethylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, and ethylene terephthalate / isophthalate copolymer; polyolefins such as polypropylene and polyethylene; and polyamides such as nylon 6 and nylon 66. Any commonly used organic resin film can be used, but a polyester resin film is preferable from the viewpoint of processing adhesion, corrosion resistance and the like.

Further, the thickness of the thermoplastic second resin film layer is preferably at least 10 μm. If the thickness is less than 10 μm, the film is inferior in scratch resistance and tends to produce pinholes and the like in film production, resulting in poor corrosion resistance.

In order to make a thermoplastic resin into a film,
A general method of forming the extruded resin into a film by a T-die method can be used. In addition, the film may be used either in a state without stretching as it is or in a state where a stretching treatment such as biaxial stretching is performed.

As a method of laminating a thermoplastic second resin film, there are a method of laminating a film in advance and a method of laminating a resin extruded and melted by a T-die method as it is.
Lamination may be performed using any method.

When the thermoplastic second resin film is laminated by heat welding, a method is generally used in which a steel plate is heated to a temperature equal to or higher than the melting point of the second resin film and the film is pressed using a roll. The laminating technique can be performed by a publicly known method that has been disclosed in a large number. For example, as a technique for laminating an organic resin film on a metal plate, Japanese Patent Application Laid-Open No. Sho 57-182428,
No. 676 discloses a method in which a metal plate side is heated to a temperature equal to or higher than the melting point of a film and bonded by heat fusion.

[0060]

Next, specific examples of the present invention will be described.

[Specimens] (1) Surface-treated steel sheet In all Examples and Comparative Examples, a low-carbon Al-killed continuous cast steel, 0.20 mm-thick T4CA material was used as an original steel strip, which will be described later. Manufactured with a surface treatment.

(2) Organic material for coating (first resin film material) Organic substance type A: terephthalic acid 4 as a dicarboxylic acid component
7mol%, isophthalic acid 48mol%, fumaric acid 5m
ol%, 1,4-butanediol 5 as a diol component
A copolymerized polyester resin having a composition ratio of 0 mol% and ethylene glycol 50 mol% was synthesized. 300 parts by weight of the copolymerized polyester resin, 700 of methyl ethyl ketone
The resulting mixture was mixed with parts by weight to obtain a polyester resin having a number average molecular weight of 18,000 (by GPC), a hydroxyl value of 10, an acid value of 5, and a glass transition temperature of 68 ° C.

Next, the polyester resin-based resin 95
Calcium carbonate-based resol type phenol resin (weight: 5000 cP, gel time: 160 sec.)
c [150 ° C], 51% non-volatile content [105 ° C / 3h],
5 parts by weight of a brown liquid) were mixed to obtain a resin composition (organic substance type A).

Organic substance types B to S, RA to RJ: Similarly, the number average molecular weight, hydroxyl value, acid value of the polyester resin synthesized by changing the monomer or the production method (solvent type, aqueous).
Table 4 shows the glass transition temperature and the composition ratio of the phenolic resin and / or the cresol-based resol-type phenolic resin or the resin composition (organic substance type B to S, RA to RJ) used as the first resin layer composed of those materials. , Table 5 collectively.

Organic substance type Z: organic solvent-based phenolic resole-type phenol resin (viscosity of 600) synthesized from 80 parts by weight of a bisphenol-type organic solvent-based epoxy resin having a number average molecular weight of about 7,000 and carboxylate / formaldehyde resin
0 cP, a gel time of 140 sec [150 ° C.], a nonvolatile content of 52% [105 ° C./3 h], 20 parts by weight of a brown liquid) were mixed to obtain a resin composition (organic substance type Z). Its number average molecular weight is 20,000, hydroxyl value is 10, acid value is 15
Met.

(3) Film lamination The surface-treated steel sheets described in Examples and Comparative Examples were prepared by
A cut sheet of 00 mm was formed, and a commercially available polyester film was laminated as a second resin film layer on both sides under the following conditions.

Film: biaxially oriented polyester film (copolymer of polyethylene glycol and terephthalic acid / isophthalic acid) Film thickness: 25 μm Film melting temperature of film: 229 ° C. Steel sheet temperature immediately before lamination: 235 ° C. Laminating speed: 2 m / Seconds Cooling after lamination: water cooling (quenching) [2] Evaluation (1) Drawing workability / Adhesion evaluation A laminated plate was punched into a 158 mm diameter disk, and a cylindrical cup was drawn at a drawing ratio of 2.92. Thereafter, the peeling state of the film on the inner surface of the cup was observed with a loupe. At that time, 5 points were set to a good state without peeling, and 4 points, 3 points, and 2 points
The evaluation was made in five steps so that the degree of peeling increased as the number of points decreased to one point.

Evaluation of Corrosion Resistance The drawn cup was immersed in a 0.4% citric acid aqueous solution at 50 ° C. for 14 days, washed with water and dried. Similarly, the degree of peeling of the inner surface of the cup was similarly evaluated on a five-point scale. did.

(2) Bending and Bending-back Process Evaluation of Adhesion A film laminating plate was cut out into a 30 x 30 mm sponge shape, a draw bead test was performed using a tool having a tip R of 0.25 mm at a holding pressure of 300 kgf, and a sample was prepared. The surface was observed with a loupe. At this time, the degree of peeling was evaluated in five steps as in the evaluation of the drawability.

Evaluation of corrosion resistance
Immersed in 0.4% citric acid aqueous solution at 50 ° C. for 14 days,
After washing with water and drying, the degree of peeling of the inner surface of the cup was similarly evaluated on a 5-point scale based on the same standard.

(3) Repacking test-Evaluation of adhesion Adhesion of a film laminated plate into a disk having a diameter of 110 mm was performed, first, a cylindrical cup drawing process was performed at a drawing ratio of 1.51, and then a redrawing was performed at a drawing ratio of 1.20. Processing,
A cylindrical cup (total drawing ratio 1.81) was prepared. The state of peeling of the film on the inner surface of the cup was observed with a magnifying glass, and the degree of peeling was evaluated in five steps based on the same standard as the evaluation of drawing workability.

Evaluation of corrosion resistance Further, 0.4% citric acid was repacked in the cup,
After dropping a 1/2 inch diameter, 1 kg steel ball from a height of 100 mm at the center of the cup, store it at 38 ° C. for 3 months, and peel off the film and metal plate on the inner surface of the cup after this storage test. Observe the situation with a magnifying glass, and
It was rated on a scale.

The workability was evaluated by visual inspection of the workability by drawing, bending and bending-back work, and repacking test based on the quality of appearance, etc., and all were evaluated as ○, and the others were evaluated as ラ.

The adhesion was evaluated by a five-step evaluation of the peeling state by observing the loupe after processing by drawing, bending and bending, repacking, and repacking test. A normal one was evaluated as Δ, and the others were evaluated as ×.

The corrosion resistance was evaluated by a five-step evaluation of the corrosion resistance after drawing by drawing, bending and bending, and repacking tests.
Were evaluated as Δ, and the others were evaluated as ×.

These evaluations were performed on Examples 1 to 50 and Comparative Examples 1 to 7 shown in Tables 1 to 3. The results are shown in Tables 1 to 3.

[0077]

[Table 1]

[0078]

[Table 2]

[0079]

[Table 3]

[0080]

[Table 4]

[0081]

[Table 5]

[0082] (Example 1) to the surface treatment the original sheet, as shown in Table 1, the metal Cr deposition amount 126 mg / m ^2, such that hydrated chromium oxide coating weight 16 mg / m ² in metal chromium conversion After subjecting to an electrolytic chromate treatment, a resin composition (organic substance type A) composed of the polyester resin and the phenolic resole type phenol resin is applied by a reverse roll coater, and dried to deposit 960 mg.
/ M ² of the organic layer. A polyester film was laminated on the surface-treated steel sheet under the conditions described above, and thereafter, workability, adhesion, and corrosion resistance were evaluated by drawing, bending and bending back, and a repack test. These evaluation results are also shown in Table 1.

As a result, the surface-treated steel sheet is not only excellent in workability after film lamination, but also excellent in adhesion after processing and corrosion resistance after processing.

(Examples 2 to 7, Comparative Examples 1 to 3) In these, as shown in Tables 1 and 3, the same conditions as in Example 1 were used except that the conditions for the electrolytic chromate treatment were variously changed. This was performed to obtain a surface-treated steel sheet. These evaluation results are also shown in Tables 1 and 3.

[0085] Table 1, as is clear from Table 3, the underlying metal chromium deposition amount, per side 30 mg / m ² or more, exemplary deposition amount of the upper layer of hydrated chromium oxide is 5 to 30 mg / m ² Example All of Nos. 2 to 7 were excellent in workability, adhesion and corrosion resistance.

On the other hand, when the amount of deposited metal chromium in the lower layer is 3
Comparative Example 1 with less than 0 mg / m ² was inferior in corrosion resistance.
The amount of hydrated chromium oxide in the upper layer was 5 mg / m ²
Comparative Example 2 with less than 1 was inferior in adhesion and corrosion resistance.
Further, the adhesion amount of the upper layer chromium hydrated oxide is 30 mg / m2.
^In Comparative Example 3 exceeding ² , the appearance was deteriorated, and the adhesion and the corrosion resistance were inferior.

(Examples 8 to 11, 35 and 36) In these, the amount of the resin composition (organic substance type A) composed of a polyester-based resin and a carboxylate-based resole-type phenolic resin was varied in various ways. The same operation as in Example 1 was performed to obtain a surface-treated steel sheet. These evaluation results are also shown in Tables 1 and 2.

As is evident from Tables 1 and 2, all of them were favorably evaluated in terms of workability, adhesion and corrosion resistance. In particular, all of Examples 8 to 11 having an adhesion amount of 50 to 10000 mg / m ² were particularly excellent in workability, adhesion, and corrosion resistance.

(Examples 12 to 18, 37 and 38) Here, as shown in Tables 4 and 5, a polyester resin constituting the first resin layer and a phenolic and / or cresol resol type phenol resin were used. The composition or composition ratio of the resin composition was changed, and otherwise the same operation as in Example 1 was performed to obtain a surface-treated steel sheet. These evaluation results are also shown in Table 1.

As apparent from Tables 1 and 2, Example 1
Nos. 2 to 18 were particularly excellent in workability, adhesion, and corrosion resistance.

(Examples 19 to 29 and 39 to 46) Here, as shown in Tables 4 and 5, the number average molecular weight, hydroxyl group, acid value, and glass of the polyester resin constituting the first resin layer are shown. Other than changing the transition temperature, the same operation as in Example 1 was performed to obtain a surface-treated steel sheet. These evaluation results are also shown in Tables 1 and 2.

As is clear from Tables 1 and 2, Example 1
Nos. 9 to 29 were particularly excellent in workability, adhesion and corrosion resistance.

(Comparative Examples 4 to 6) In Comparative Example 4, a surface-treated steel sheet was obtained by performing the same operation as in Example 1 except that the first layer, which is a conventional technique, was not formed. Comparative Example 5
In Example 1, a surface-treated steel sheet was obtained by performing the same operation as in Example 1 except that only the copolymerized polyester resin was used as an organic material layer (organic material type Y). In Comparative Example 6, a surface-treated steel sheet was obtained by performing the same operation as in Example 1 except that an epoxy phenol resin (organic material type Z) was used as the organic material layer.

Table 3 also shows the results of these evaluations.

As is evident from Table 3, the corrosion resistance was poor in all cases.

(Examples 30 to 32 and 47, Comparative Example 7) Here, the thickness of the second resin film layer was set to 10 μm.
(Example 30), 50 μm (Example 31), 80 μm
(Example 32) The surface-treated steel sheet was obtained by changing the thickness to 8 μm (Example 47), and otherwise performing the same operation as in Example 1. In Comparative Example 7, a surface-treated steel sheet was obtained by performing the same operation as in Example 1 except that the second resin film layer was not formed. These evaluation results are shown in Tables 2 and 3.

As is clear from Tables 2 and 3, Example 3
0 to 32 were particularly excellent in workability, adhesion and corrosion resistance. Comparative Example 7 having no film was inferior in corrosion resistance.

(Examples 33, 34, and 48 to 50) In this example, the surface treatment was performed by changing the second resin film layer from copolymerized polyester to homo-PET, and performing the same operations as in Example 1 except for that. A steel plate was obtained (Example 33).

In this case, the same copolymerized polyester resin as in Example 1 extruded and melted by the T-die method was directly laminated to form a 25 μm film layer.
Otherwise, the same operation as in Example 1 was performed to obtain a surface-treated steel sheet (Example 34). In Examples 48 to 50, the second
The surface treatment was performed in the same manner as in Example 1 except that the resin film layer was changed to a polypropylene layer (Example 48), a polyethylene layer (Example 49), and a nylon 6 layer (Example 50) having a thickness of 25 μm. A steel plate was obtained. These evaluation results are shown in Tables 2 and 3.

As is clear from Tables 2 and 3, Example 3
Nos. 3 and 34 were particularly excellent in workability, adhesion, and corrosion resistance.

[0101]

As described above, according to the present invention,
Even when subjected to severe processing after film lamination, it has excellent processing adhesion and corrosion resistance, and can respond to the increase in the degree of processing due to thinning of the can body, and requires retort treatment Provided is a film-laminated steel plate for a two-piece can that can be applied to all contents such as contents. As described above, according to the present invention, since excellent working adhesion and working corrosion resistance can be obtained without going through complicated steps, its economic value is extremely high.

Continuing on the front page (72) Inventor Junichi Kitagawa 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Inventor Hiroki Iwasa 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Stock In-house (72) Inventor Akihiko Morito 1638-1-427 Imajuku-Higashicho, Asahi-ku, Yokohama-shi, Kanagawa Prefecture F-term (reference) 4F100 AA22B AA22C AB03A AK01E AK34D AK34J AK41D AK41E AK41J AL05D BA05 BA07 BA26 EJ61C EJ69B GBD JA05 JA05 JL00 JL11 YY00D

Claims (3)

[Claims] 1. A steel sheet and a metal chromium layer formed on at least one surface of the steel sheet, wherein a lower layer has an adhesion amount of 30 mg / m ² or more per side, and an upper layer has 5 to 30 mg in terms of metal chromium per side. / M ² , an electrolytic chromate treatment layer of a hydrated chromium oxide layer having an adhesion amount of, and a polyester resin and a phenolic resin and / or a cresol resol type phenol resin formed on the electrolytic chromate treatment layer as main components. 2 characterized by comprising a first resin layer and a thermoplastic second resin film layer formed on the first resin layer, characterized by having excellent processing adhesion and corrosion resistance.
Film laminated steel sheet for piece cans. 2. The resin composition according to claim 1, wherein the first resin layer has an average adhesion amount of 50 to 10,000 mg / m ² as a solid concentration, and a main component of the resin composition has a number average molecular weight of 3,000 to 3,000.
0, a hydroxyl value of 5 to 30, an acid value of 0 to 50, a glass transition temperature of 5 to 110 ° C., 60 to 99 parts by weight of a polyester resin, and 1 to 40 parts by weight of phenolic and / or cresol resole phenolic resin. The film-laminated steel sheet for a two-piece can according to claim 1, which is excellent in processing adhesion and corrosion resistance. 3. The two-piece resin according to claim 1, wherein the thermoplastic second resin film layer is a polyester resin film layer having a thickness of 10 μm or more. Film-laminated steel sheet for cans.