JP2006095693A - Press-molded can and lid excellent in sulfurization discoloring resistance and corrosion resistance - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a press-molded can not exposing a metal during processing, causing no blackening even against hydrogen sulfide, not causing the peeling of a resin coating or the occurrence of a crack after the filling with content and excellent in corrosion resistance or the preservation of content. <P>SOLUTION: In the press-molded can having a tin plating layer, a tin-zinc alloy layer, a non-chromium surface-treated layer and a thermoplastic resin layer formed thereto, the amount of Sn of the tin plating layer is 0.8 g/m<SP>2</SP>or above and the amount of Zn in the tin-zinc alloy layer is 0.06-0.5 g/m<SP>2</SP>. The non-chromium surface-treated layer comprises at least one of a surface treatment layer based on a silane coupling agent, a surface treatment layer due to a water-soluble phenolic compound and an inorganic surface treatment layer containing Zr and/or Ti and the thermoplastic resin layer is formed of a polyester thermoplastic resin with a melting point of 200-235°C. The peel strength of the resin coating applied to the upper part of a can body after retort treatment is 100 g/15 mm width or above. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a press-molded can and a lid made of a non-chromium surface-treated steel sheet, and more particularly to a press-molded can and a lid that are excellent in resistance to sulfur discoloration, corrosion resistance, and heat sterilization resistance.

  The contents filled in metal packages for food, beverages, etc. are heated like boiled seafood, boiled meat, boiled vegetables such as sweet corn, green peas, etc. Some generate hydrogen sulfide gas during sterilization and storage. Conventionally, tin (tin-plated steel sheet), which has been widely used for such contents, has been prevented from blackening sulfide by applying a chromium-based surface treatment to the tin-plated surface.

  However, this chromium-based surface treatment is produced by cathodic electrolysis treatment of a tin-plated steel sheet in a treatment solution containing hexavalent chromium and washing it with water. Although hexavalent chromium is not included in the coating, harmful hexavalent chromium is contained in the treatment liquid, so it has various problems due to environmental problems, and it is required not to use hexavalent chromium in the treatment liquid. Has been.

  In addition, when a press-molded can (two-piece can) is manufactured by press forming such as the above-described chromate-based surface-treated tin-plated steel sheet or by drawing and ironing, the chromate-treated film or chromic acid-treated film is destroyed by drawing or the like. It has been difficult to solve the problem that blackening occurs when the tin surface of the base is exposed and is filled with contents that generate hydrogen sulfide.

In order to solve such a problem, an electroplating layer made of Sn having a basis weight of 1 to 15 g / m ² and a basis weight of 0.0071 to 0.71 g are formed on at least one surface of the low-carbon cold rolled steel sheet. An electroplating layer made of Zn of / m ² , and the weight ratio of the Sn plating layer to the total plating layer is at least 58.4%, and the electric tinting excellent in sulfuration resistance and smudge resistance ( Patent Document 1) has been proposed.

Japanese Examined Patent Publication No. 53-47216

  In general, the inner surface of a press-molded can filled with food is formed with a coating film mainly composed of a thermosetting resin in order to maintain the flavor of the contents and improve the corrosion resistance. In order to form a film, since the environmental load by the volatile organic compound (VOC) contained in the solvent of the paint is large, a resin coating with a polyester resin or the like is performed instead of using the paint.

However, a resin-coated steel sheet coated with such a polyester resin is prepared on a surface-treated plated steel sheet containing metallic zinc as described in Patent Document 1 above, and this is press-molded to produce a can. In addition, when filled with contents that may generate hydrogen sulfide such as seafood, meat, vegetables, etc. and stored after retort sterilization, the polyester resin coating partially peels off and corrosion occurs from that part. The problem of doing.
In addition, in the contents as described above, steaming may be performed by spraying water vapor for a predetermined time from the top of the can with the contents filled in the can. Even when such steaming is performed, the polyester resin coating is The problem of peeling off occurred.

Accordingly, an object of the present invention is to include a non-chromium surface-treated steel sheet, a content that generates hydrogen sulfide without using metal paint, no metal exposure even after drawing or other severe processing. It is to provide a press-molded can that does not turn black.
Another object of the present invention is that there is no occurrence of peeling or cracking of the resin coating even after high temperature after cooking and sealing of the content after filling the content, and heat sterilization for a long time, and it is excellent in corrosion resistance and preservation of the content. Is to provide a pressed can.
Still another object of the present invention is to provide a lid excellent in sulfur discoloration resistance, adhesiveness of a thermoplastic resin coating, and the like that can be suitably used for the press-molded can.

According to the present invention, a resin-coated surface-treated steel sheet in which a tin plating layer, a tin-zinc alloy layer, a non-chromium surface treatment layer, and a thermoplastic resin layer are formed in order from the steel plate side on the steel plate on the side that becomes the inner surface of the can is pressed. A press-molded can formed by molding, wherein the tin plating layer has an Sn amount of 0.8 g / m ² or more, and the tin-zinc alloy layer has a Zn amount of 0.06 to 0.5 g / m ² . There is provided a press-molded can characterized in that the peel strength of the thermoplastic resin layer at the upper portion of the can body after the retort treatment has a peel strength of 100 g / 15 mm width or more.

In the press-molded can of the present invention,
1. The Sn amount of the tin plating layer is 0.8 to 12 g / m ² ;
2. The thermoplastic resin layer is formed of a polyester thermoplastic resin having a melting point of 200 to 235 ° C .;
3. The non-chromium surface treatment layer comprises at least one of a surface treatment layer mainly composed of a silane coupling agent, a surface treatment layer made of a water-soluble phenol compound, and an inorganic surface treatment layer containing Zr and / or Ti,
4). In the surface treatment layer mainly composed of a silane coupling agent, the Si amount is ² to 55 mg / m ² .
5. 5. In the surface treatment layer with a water-soluble phenol compound, the C amount is 0.8 to 50 mg / m ² . The inorganic surface treatment layer containing Zr and / or Ti is formed by intermittent cathodic electrolysis using an aqueous solution mainly composed of Zr and / or Ti, O, F;
7. The surface treatment layer is formed by carrying out an inorganic surface treatment containing Zr and / or Ti, followed by a surface treatment mainly comprising a silane coupling agent or a surface treatment with a water-soluble phenolic compound. Being
8). The polyester thermoplastic resin is a copolymer resin of polyethylene terephthalate and / or a copolymer resin of polybutylene terephthalate,
9. The polyester-based thermoplastic resin layer is formed by blending a polyester-based thermoplastic resin with a polyolefin,
10. The polyester-based thermoplastic resin is subjected to corona treatment,
11. Before the retort treatment, Tm−40 ° C. to Tm + 10 ° C. (Tm: melting point of the base thermoplastic resin used for the thermoplastic resin layer bonded to the surface treatment layer)
Is preferred.

According to the present invention, in order from the steel sheet side on to the steel plates to be at least the can inner surface side, Sn amount is 0.8 g / ^{m 2} or more of the tin plating layer, Zn amount of 0.06~0.5g / ^{m 2} There is provided a lid comprising a resin-coated surface-treated steel sheet formed with a tin-zinc alloy layer, a non-chromium surface treatment layer, and a polyester thermoplastic resin layer having a melting point of 200 to 235 ° C.

In the present invention, from the steel sheet side on to the steel plates to be at least the can inner surface side, Sn amount is 0.8 g / ^{m 2} or more of the tin plating layer, Zn amount of 0.06~0.5g / ^{m 2} of tin, zinc It consists of an alloy layer, a non-chromium surface treatment layer, and a resin-coated metal plate formed with a thermoplastic resin layer, so that it has excellent corrosion resistance and anti-sulfur discoloration, and the resin coating on the top of the can body after retorting. Since the peel strength is 100 g / 15 mm width or more, it is excellent in processing adhesion to the surface-treated steel sheet of thermoplastic resin, and has excellent adhesion even after retorting, so that it can express excellent corrosion resistance over a long period of time. Excellent preservation of contents.

The present invention press-molds a resin-coated surface-treated steel sheet in which a tin plating layer, a tin-zinc alloy layer, a non-chromium surface treatment layer, and a thermoplastic resin layer are formed on a steel plate on the side that is the inner surface of the can in order from the steel plate side. A tin-plated layer of a resin-coated surface-treated steel sheet to be used, the Sn amount of which is 0.8 g / m ² or more, and the Zn amount in the tin-zinc alloy layer is 0.06 to 0.5 g / it is the first feature is a m ^2.

  In the present invention, a tin-zinc alloy layer is formed on the tin-plated layer in order to improve the resistance to sulfur discoloration due to the contents, but a thermoplastic resin coating is formed on the surface-treated tin-plated steel sheet containing zinc. In this case, the adhesiveness of the thermoplastic resin coating, particularly the adhesiveness after heat treatment such as retort sterilization, is remarkably inferior to that of the surface-treated steel sheet with a tin plating layer alone, and this should be prevented. By using a resin-coated surface-treated steel sheet having the above-mentioned configuration, a press-molded can capable of being sterilized by retort that has corrosion resistance, anti-sulfur discoloration and adhesiveness of a thermoplastic resin coating is provided. It became possible.

That is, when the amount of tin plating is less than the above value, the adhesiveness of the thermoplastic resin coating is lowered, and the coating on the steel plate surface is not sufficient, so organic acids such as acetic acid and citric acid are included. When the contents are filled, the organic acid tends to permeate the thermoplastic resin and cause corrosion (see Comparative Example 1 described later). Although the tin plating amount should just be more than the said value, it is preferable that the tin plating amount exists in the range of 0.8-12 g / m < ² > from the point of economical efficiency.
Further, when the zinc content of the tin-zinc alloy layer is less than the above range, satisfactory sulfur discoloration resistance cannot be obtained (see Comparative Examples 4 and 5 described later), while the zinc content is larger than the above range. In this case, the adhesiveness of the thermoplastic resin coating is lowered (Comparative Examples 2 and 3 described later), and the color tone is darker and the performance as a printing base tends to be lower than when zinc is in the above range. is there.

In the press-molded can of the present invention, the second characteristic is that the peel strength of the thermoplastic resin layer in the upper portion of the can body after the retort treatment has a peel strength of 100 g / 15 mm width or more, particularly 170 g / 15 mm width or more. .
In the present invention, the peel strength of the resin coating on the upper portion of the can body after retorting is a problem. If this peel strength is equal to or greater than the above value, film peeling or corrosion occurs even when subjected to an actual can storage test. This is because it can be simply expressed that no occurs. That is, as described above, the adhesion of the resin coating, that is, the peel strength is greatly reduced by being subjected to the retort treatment after filling the contents, so the adhesion of the thermoplastic resin coating is evaluated based on the peel strength after the retort. As will be apparent from the examples described later, since this evaluation corresponds to the result of the actual can storage test, the cans whose peel strength after retorting is equal to or higher than the above values are actually filled with the contents. In addition, it is considered that it is assured that no film peeling or corrosion occurs even when stored through steaming, sealing, retort sterilization or the like.

  In the press-molded can of the present invention, in order to make the peel strength of the thermoplastic resin layer at the upper portion of the can body after the retort treatment equal to or higher than the above value, the kind of the non-chromium surface treatment layer of the resin-coated surface-treated steel sheet, the thermoplastic resin layer Of the thermoplastic resin layer at the upper part of the can body after the retort treatment can be obtained by appropriately selecting the kind of resin, the physical properties of the resin, the presence or absence of the surface treatment of the resin film, or the heat treatment after press molding. Various combinations can be adopted as long as the strength is not less than the above value.

  The peel strength after the retort treatment is based on the upper part of the can body of the press-molded can because the upper part of the can body is subjected to the most severe processing of the resin coating in the press molding, and good results are obtained at this point. This is because there is no problem in other places. In addition, although the location which can be measured differs depending on the height of the can body, it is generally preferable to measure at the location within a range of 1 to 15% of the can height from the upper end of the can. The retort treatment conditions vary depending on the type of contents, the filling amount, the size of the can, etc., and cannot be defined unconditionally, but conventionally known retort treatment conditions, generally 20 to 220 at a temperature of 105 to 130 ° C. Any device that has been subjected to a minute retort treatment may be used.

FIG. 1 is a diagram showing an example of a cross-sectional structure of a resin-coated surface-treated steel sheet used for a press-formed can according to the present invention. It consists of a tin-zinc alloy layer 3, a non-chromium surface treatment layer 4, and a thermoplastic resin layer 5. On the other hand, a tin-iron alloy layer 6 and a metal tin layer 7 are formed on the surface of the steel plate 1 on the outer surface side of the can. ing.
In the above specific example, the thermoplastic resin layer 5 is formed as a single layer, but the resin coating is not limited to a single layer, and the thermoplastic resin layer 5 is made of another thermoplastic resin on the thermoplastic resin layer 5. Layers can also be formed. Also, a resin coating can be formed on the metal tin layer 7 on the surface which is the outer surface side of the can.

(Resin-coated surface-treated steel sheet)
The resin-coated surface-treated steel sheet used for forming the press-molded can of the present invention has a tin plating layer, a tin-zinc alloy layer, a non-chromium surface treatment layer, A plastic resin layer is formed, and it is preferable that a tin plating layer is preferably formed also on the steel plate surface on the side that becomes the outer surface of the can.

[steel sheet]
As the steel sheet used in the present invention, a conventionally known cold-rolled steel sheet or the like that has been used for can manufacturing can be used, and the sheet thickness is preferably about 0.07 to 0.4 mm. In order to improve the corrosion resistance of the cold-rolled steel sheet, the surface of the cold-rolled steel sheet can be made into a Ni diffusion layer by annealing after thin Ni plating.

[Tin plating layer]
Tin plated layer provided on the surface to be at least the can inner surface side of the steel sheet, as described above, the amount of tin 0.8 g / ^{m 2} or more, especially 0.8~12g / ^{m 2,} in particular 1.0~9g / m By forming a tin plating layer on the steel sheet so as to be in the range of ² and controlling the heating conditions after coating the thermoplastic resin, the corrosion resistance of the steel sheet itself is improved, and a specific non-chromium surface treatment layer This combination improves the work adhesion with the thermoplastic resin coating and the adhesion after retorting, thereby improving the corrosion resistance.
Moreover, it is desirable to provide a tin plating layer also on the surface to be the outer surface side of the steel plate, and the tin amount is desirably 0.8 to 12 g / m ² , similar to the inner surface side. In addition, it does not prevent using the surface treatment steel plate which formed the tin plating layer and the tin-zinc alloy layer in order on both surfaces.

In this invention, it can also be set as the two-layer structure of a tin plating layer / tin iron alloy layer by making a part of the steel plating side of the tin plating layer provided on a steel plate into a tin iron alloy.
In order to form a tin-plated layer in a two-layer structure of a tin-plated layer / tin-iron alloy layer, a predetermined amount of tin is plated on a steel sheet, and then heated to a temperature equal to or higher than the melting point of tin and then cooled (reflow treatment). ) To change a part of the tin-plated layer on the steel plate side to a tin-iron alloy layer, or at the same time as the reflow treatment for forming the tin-zinc alloy layer after galvanizing described later, -It can also be changed to an iron alloy layer. The alloying is desirably 5 to 50% of the amount of tin contained in the tin plating layer.
By forming the tin-iron alloy layer in this manner, the work adhesion can be improved and the corrosion resistance of the steel plate itself can be improved.

[Tin-zinc alloy layer]
The tin-zinc alloy layer provided on the tin plating layer formed on the steel plate surface on the inner surface of the can has a zinc content of 0.06 to 0.5 g / m ² , particularly 0.07 to 0.48 g / m ² . After galvanizing on the tin plating layer to be in the range, reflow treatment after cooling at a temperature equal to or higher than the melting point of tin, or by reflow treatment after tin plating, then galvanizing, heat It is formed by performing preheating for plastic resin coating and heating for baking after painting.
By forming the tin-zinc alloy layer, it is possible to suppress the reaction between hydrogen sulfide and tin that cause sulfur discoloration due to the presence of zinc, while 0.06 to 0.5 g of zinc is contained in the tin-zinc alloy layer. Since it is present in a small amount of / m ² , it is effectively prevented that the adhesiveness of the thermoplastic resin coating is impaired. Further, if the tin-zinc alloy layer is in a small amount (to the extent that the metal zinc does not cover the entire surface of the tin-zinc alloy layer), the metal zinc can remain.

[Non-chromium surface treatment layer]
The non-chromium surface treatment layer formed on the tin-zinc alloy layer includes a surface treatment layer mainly composed of a silane coupling agent, a surface treatment layer made of a water-soluble phenol resin, and an inorganic surface treatment containing Zr and / or Ti. It is preferable to consist of at least one of the layers, thereby improving the adhesion of the thermoplastic resin coating, and as described above, the peel strength of the resin coating on the upper portion of the can body after retorting is a value of 100 g / 15 mm width or more. This makes it possible to improve the corrosion resistance.
The surface treatment layer is preferably formed by any of the above treatments, and it is particularly preferable to perform a combination of inorganic surface treatment and organic surface treatment. In this case, it is preferable to perform an inorganic surface treatment first and then an organic surface treatment to form a composite treatment film.

・ Silane coupling agent surface treatment layer The silane coupling agent treatment layer formed on the tin-zinc alloy layer improves the adhesion between the tin plating layer and the thermoplastic polyester resin layer due to the reactive group of the silane coupling agent. It becomes possible to make it. The silane coupling agent treatment layer itself improves durability and water resistance, while suppressing gas permeation to the tin plating layer, thereby suppressing the formation of an oxide film on the tin plating layer. A decrease in the adhesion of the organic resin coating layer due to the growth can be prevented.
The silane coupling agent surface treatment layer is preferably formed so that the Si amount is ² to 50 mg / m ² , particularly 2.5 to 40 mg / m ² .

The silane coupling agent used to form the silane coupling agent surface treatment layer has a reactive group that chemically bonds to the organic resin coating and a reactive group that chemically bonds to the tin-plated steel sheet, an amino group, an epoxy group, Containing reactive groups such as methacryloxy and mercapto groups and organosilanes containing hydrolyzable alkoxy groups such as methoxy and ethoxy, and organic substituents such as methyl, phenyl, epoxy and mercapto Silanes containing decomposable alkoxy groups can be used.
Specific examples of silane coupling agents that can be suitably used in the present invention include γ-APS (γ-aminopropyltrimethoxysilane), γ-GPS (γ-glycidoxypropyltrimethoxysilane), BTSPA ( Bistrimethoxysilylpropylaminosilane), N-β (aminoethyl) γ-aminopropyltrimethoxysilane, and the like.

In order to form the silane coupling agent treatment layer on the tin-zinc alloy layer, the above-described silane coupling agent solution is applied onto the tin-zinc alloy layer, or the tin plating layer and the tin are added to the silane coupling agent solution. -It can form by immersing the steel plate in which the zinc alloy layer was formed, and removing an excess solution with a squeeze roll after that. Suitable silane coupling agent solution combinations and processing sequences are as follows.
(i) It is formed by treatment using an amino group-containing silane solution and / or an epoxy group-containing silane coupling agent solution.
(ii) It is formed by treatment using a mixed solution comprising a silane coupling agent containing an amino group and / or an epoxy group, a silane containing an organic substituent and a hydrolyzable alkoxy group.
(iii) After treatment with a silane containing an organic substituent and a hydrolyzable alkoxy group, a treatment is performed using a silane coupling agent solution comprising an amino group-containing silane solution and / or an epoxy group-containing silane solution.

Water-soluble phenol-based surface treatment layer of tin comprising a compound - zinc surface treatment layer made of a water-soluble phenolic compounds formed alloy layer is, C amount 0.8~50mg / ^{m 2,} in particular 1 to 40 mg / it is preferable to form such a range of m ^2, it can be formed by using a water-soluble phenolic resin comprising a polymer of formula (1)

OH
｜
− Φ −CH ₂ − (1)
｜
X
In the formula, φ represents a benzene ring, X represents a hydrogen atom or the following formula (2)
Z = —CH ₂ —N—R ₁ (2)
｜
R ₂
In the formula, each of R ₁ and R ₂ represents Z represented by an alkyl group having 10 or less carbon atoms or a hydroxyalkyl group having 10 or less carbon atoms, and the introduction rate of the group Z is 0 per benzene ring. .2 to 1.0
It is preferable that it is a phenol resin which consists of a repeating unit represented by these.

Another example of the water-soluble phenol compound is tannin. Tannin, also called tannic acid, is a general term for aromatic compounds having a complex structure having a phenolic hydroxyl group.
Examples of tannins include hameli tannins, oyster tannins, chatannins, pentaploid tannins, gallic tannins, milovalan tannins, dibidi tannins, argarovira tannins, valonia tannins, catechin tannins and the like. Tannin preferably has a number average molecular weight of 200 or more.

In the present invention, in addition to forming the surface treatment layer with the water-soluble phenolic compound alone, the surface treatment layer can also be formed by adding an inorganic substance such as zirconium or titanium to the water-soluble phenolic compound. Can be further improved.
The inorganic substance is preferably contained in an amount of 4 to 3750% by weight of the total carbon.
In order to form the surface treatment layer with the water-soluble phenol-based compound on the tin-zinc alloy layer, the above-described water-soluble phenol-based compound can be formed on the surface of the tin-zinc alloy layer by drying.

Inorganic surface treatment layer containing Zr and / or Ti The inorganic surface treatment layer containing Zr and / or Ti formed on the tin-zinc alloy layer is a treatment liquid containing Zr and / or Ti as a main component. In the present invention, it is preferably formed by cathodic electrolysis in an aqueous solution containing these inorganic components and O, F and not containing phosphoric acid. .
The treatment liquid used for the surface treatment is preferably an aqueous solution having a bath concentration of Zr and / or Ti in the range of 0.010 to 0.050 mol / liter, and a pH of 3.0 to 8.0. It is preferable.

As the Zr chemical used in the treatment liquid, potassium zirconium fluoride KZrF ₆ , zirconium ammonium fluoride (NH ₄ ) ₂ ZrF ₆ , zirconium ammonium carbonate solution (NH ₄ ) ₂ ZrO (CO ₃ ) ₂ or the like can be used. As the Ti agent, titanium potassium fluoride K ₂ TiF ₆ , titanium ammonium fluoride (NH ₄ ) ₂ TiF ₆ , sodium titanium fluoride Na ₂ TiF _{6 and the} like can be used.
In addition, titanium ions, zirconium ions, and fluorine ions can be supplied from separate agents. As Ti agents, potassium titanium oxalate dihydrate K ₂ TiO (C ₂ O ₄ ) ₂ · 2H ₂ O, titanium chloride ( III) Solution TiCl ₃ , Titanium chloride (IV) solution TiCl _4, etc. Zr agents such as zirconium oxynitrate ZrO (NO ₃ ) ₂ , zirconium oxyacetate ZrO (CH ₃ COO) ₂ etc., F agents such as sodium fluoride NaF, fluorine For example, potassium fluoride KF, ammonium fluoride NH ₄ F, or the like can be used.
The F concentration in the bath is preferably in the range of 0.03 mol / liter to 0.35 mol / liter as F.
Further, in the treatment liquid, it is preferable to add water-dispersible silica having a particle size of 4 to 80 nm in a range of ³ to 100 mg / m ^{2 in} terms of Si amount from the viewpoint of corrosion resistance and film forming property, and further if necessary. Nitrate ions, peroxides and complexing agents can also be added.

As the pretreatment of the surface treatment, degreasing, washing with water, and if necessary, pickling and washing with water are performed to clean the surface, and the above treatment liquid is treated at a temperature of 30 to 65 ° C. at 3 to 100 A / dm. ^A suitable surface treatment layer can be obtained by performing cathodic electrolysis intermittently at 0.3 to 20 seconds and finally washing with water.
As the counter electrode plate corresponding to the anode side, a titanium plate coated with iridium oxide is preferably used. As a condition of the counter electrode plate, it is desirable that the counter electrode material is an insoluble anode having a small oxygen overvoltage without being dissolved in the treatment liquid during electrolysis.
The thickness of the surface treatment layer to be formed is preferably 5 to 300 mg / m ² in terms of the weight film thickness of Zr and / or Ti from the viewpoint of coating uniformity and work adhesion.

[Thermoplastic resin]
In the present invention, the thermoplastic resin applied on the non-chromic surface treatment layer includes polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, ethylene-acrylic ester copolymer, ionomer, etc. Olefin-based resins, polyester resins such as polybutylene terephthalate, polyamide resins such as nylon 6, nylon 6,6, nylon 11 and nylon 12, thermoplastic resins such as polyvinyl chloride films and polyvinylidene chloride films However, polyester thermoplastic resins, particularly polyester thermoplastic resins having a melting point of 200 to 235 ° C. are preferred.
When the melting point of the polyester-based thermoplastic resin is smaller than the above range, the barrier property of the polyester resin is lowered, and the peel strength at the upper part of the can body after retort, which is an important feature of the present invention, is reduced. Since the corrosion resistance is poor (Comparative Example 11 to be described later), corrosion tends to occur particularly when the tin plating amount is small, whereas when the melting point is larger than the above range, the polyester heat The temperature required to coat the plastic resin well becomes close to the melting point of tin (232 ° C.) or exceeds the melting point of tin, the coating state becomes uneven, and the adhesion becomes unstable. Also, the peel strength at the upper part of the can body after retort tends to be lowered.

Examples of the polyester resin include thermoplastic polyesters derived from an alcohol component mainly composed of ethylene glycol or butylene glycol and an acid component such as an aromatic dibasic acid such as terephthalic acid, isophthalic acid, or naphthalenedicarboxylic acid. In the present invention, a copolymer polyester resin mainly composed of ethylene terephthalate units or butylene terephthalate is preferable so that the melting point is in the above range.
Generally, 70 mol% or more, particularly 75 mol% or more of the dibasic acid component in the copolyester is composed of a terephthalic acid component, and 70 mol% or more, particularly 75 mol% or more of the diol component is composed of ethylene glycol or butylene glycol, It is preferable that 1 to 30 mol%, particularly 5 to 25 mol% of the dibasic acid component is composed of a dibasic acid component other than terephthalic acid.
Dibasic acids other than terephthalic acid include aromatic dicarboxylic acids such as isophthalic acid, phthalic acid and naphthalenedicarboxylic acid: alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid: succinic acid, adipic acid, sebacic acid, dodecanedioic acid, etc. Or a combination of two or more of the aliphatic dicarboxylic acids: As the diol component other than ethylene glycol or butylene glycol, propylene glycol, diethylene glycol, 1,6-hexylene glycol, cyclohexane dimethanol, bisphenol A 1 type, or 2 or more types, such as an ethylene oxide adduct. Of course, the combination of these comonomers is preferably such that the melting point of the copolyester falls within the above range.

Further, the polyester may contain at least one branching or crosslinking component selected from the group consisting of a tribasic or higher polybasic acid and a polyhydric alcohol in order to improve the melt flow characteristics during molding. . These branching or crosslinking components should be in the range of 3.0 mol% or less, preferably 0.05 to 3.0 mol%.
Examples of the trifunctional or higher polybasic acid and polyhydric alcohol include trimellitic acid, pyromellitic acid, hemimellitic acid, 1,1,2,2-ethanetetracarboxylic acid, 1,1,2-ethanetricarboxylic acid, 1 , 3,5-pentanetricarboxylic acid, 1,2,3,4-cyclopentanetetracarboxylic acid, polybasic acids such as biphenyl-3,4,3 ′, 4′-tetracarboxylic acid, pentaerythritol, glycerol, Examples thereof include polyhydric alcohols such as trimethylolpropane, 1,2,6-hexanetriol, sorbitol, 1,1,4,4-tetrakis (hydroxymethyl) cyclohexane.

The polyester-based thermoplastic resin layer is preferably blended with polyolefin for the purpose of improving high-temperature wet heat resistance and impact resistance. This polyolefin is generally preferably used in an amount of 5 to 25 parts by weight per 100 parts by weight of the polyester resin.
Examples of polyolefins include low-, medium- or high-density polyethylene, linear low density polyethylene, polypropylene, linear ultra-low density polyethylene, ethylene-propylene copolymer, ethylene-butene-1 copolymer, ethylene- Examples thereof include a propylene-butene-1 copolymer, an ethylene-vinyl acetate copolymer, an ion-crosslinked olefin copolymer (ionomer), and an ethylene-acrylic acid ester copolymer. Among these, ionomers are preferable, and as the base polymer of ionomer, ethylene- (meth) acrylic acid copolymer, ethylene- (meth) acrylic acid ester- (meth) acrylic acid copolymer, ion As the seed, Na, K, Zn or the like is used.

The polyester-based thermoplastic resin film used in the present invention has been subjected to surface modification by corona discharge treatment to improve the adhesion of the polyester-based thermoplastic resin layer, and the resin coating on the upper portion of the can body after retorting The peel strength is preferably 100 g / 15 mm width or more. The corona discharge treatment can be performed by a conventionally known method. Generally, in an atmosphere of air, nitrogen gas, oxygen gas, argon gas, carbon dioxide gas, etc., at a treatment speed of 1 to 300 m / min at an output of 1 to 40 kW. Can be processed.
The thermoplastic resin layer may be a single layer or a multilayer resin layer. When the thermoplastic resin layer is a multilayer resin layer, the above-described polyester resin layer having an excellent melting point of 200 to 235 ° C. is the surface treatment layer side. It is preferable to select a polyester resin having a composition excellent in content resistance, that is, extraction resistance and non-adsorption of flavor components, on the surface layer side.

In the thermoplastic resin layer, known compounding agents for resins, for example, antiblocking agents such as amorphous silica, inorganic fillers, various antistatic agents, lubricants, antioxidants, ultraviolet absorbers and the like according to known formulations. Can be blended.
Of these, tocopherol (vitamin E) or polyphenol is preferably used. Tocopherols or polyphenols are conventionally known as anti-oxidants that prevent the decrease in molecular weight due to degradation during heat treatment of polyester resins and improve dent resistance. When this tocopherol or polyphenol is blended with a polyester composition blended with polyolefin as a modified resin component, not only dent resistance but also severe conditions such as retort sterilization and hot bender have caused cracks in the coating. Even in this case, corrosion can be prevented from proceeding from the cracks, and the effect of significantly improving the corrosion resistance can be obtained.
Tocopherol or polyphenol is preferably blended in an amount of 0.05 to 3% by weight, particularly 0.1 to 2% by weight.

The thickness of the thermoplastic resin layer of the present invention is preferably in the range of 3 to 80 μm, particularly 5 to 70 μm. When the thickness of the thermoplastic resin layer is below the above range, the corrosion resistance becomes insufficient, and when the thickness exceeds the above range, a problem is likely to occur in terms of workability.
In order to form the thermoplastic resin layer on the steel plate on which the non-chromium surface treatment layer is formed, any conventionally known means can be used, for example, extrusion coating method, cast film thermal bonding method, film thermal bonding method, etc. Can be performed.
When a film is used, the film can be obtained by a T-die method or an inflation film forming method. The film is preferably an unstretched film formed by a cast molding method in which the extruded film is rapidly cooled, because it has no distortion of the film and is excellent in workability and adhesion. A biaxially stretched film produced by simultaneously biaxially stretching and heat-setting the stretched film can also be used.

[Layer structure]
As described above, the resin-coated surface-treated steel sheet used in the present invention is formed by providing a tin plating layer, a tin-zinc alloy layer, a non-chromium surface treatment layer, and a thermoplastic resin layer in this order on at least the steel sheet surface on the inner surface of the can. However, if necessary, other layers can be provided. That is, a tin coating layer and an organic resin coating can be provided on the steel plate surface on the outer side of the can as well as the inner side, and a white coat layer, a printing layer, and the like can be provided on the thermoplastic resin layer.

(Press-formed can and its manufacturing method)
As long as the press-molded can of the present invention is formed from the above-described resin-coated surface-treated steel sheet, it can be molded by any press-molding method, and the thermoplastic resin layer of the resin-coated surface-treated steel sheet is on the can inner surface side. Manufactured by applying to press forming means such as drawing, drawing / re-drawing, bending / stretching by drawing / re-drawing (stretching), bending / stretching / drawing by drawing / re-drawing or drawing / ironing. Is done.
FIG. 2 is a side view showing an example of the press-formed can of the present invention. The press-formed can 11 is formed by drawing the resin-coated surface-treated steel plate described above, and includes a bottom portion 12 and a body portion 13. I have. The bottom part 12 and the trunk | drum 13 are connected seamlessly.
In order to provide pressure resistance, one or a plurality of beads can be provided on the can body, and an expansion ring can be provided on the bottom of the can.

  The press-molded can of the present invention is 0 in the range of Tm−40 ° C. to Tm + 10 ° C. (Tm: melting point of the base thermoplastic resin used for the thermoplastic resin layer bonded to the surface treatment layer) before being subjected to the retort treatment. It is preferable that the heat treatment is performed for about 5 to 120 seconds in order to make the peel strength of the thermoplastic resin layer at the upper part of the can body after retorting 100 g / 15 mm width or more.

(Lid and its manufacturing method)
As long as the lid of the present invention is formed from the above-mentioned resin-coated surface-treated steel sheet, any conventionally known lid-making method may be used. In addition to lids that do not have an easy-open function, in general, they can be molded into the shape of a stay-on-tab-type easy-open can lid or a full-open type easy-open can lid, and should be suitably used for the above-mentioned press-molded cans Can do.
In FIG. 3 which shows the upper surface of an example of the lid | cover of this invention, and FIG. 4 which expands and shows a cross section, this lid | cover 20 is formed from the resin-coated surface-treated steel plate mentioned above, and is fitted by the can body side surface inner surface. A sealing groove 22 is provided on the outer peripheral side via a power annular rim portion (counter sink) 21, and a score 24 formed over the entire circumference defining a portion 23 to be opened is formed inside the annular rim portion 21. Is provided. Inside the portion 23 to be opened, there is a substantially semicircular recess panel 25 formed by pushing a substantially central portion, a dimple 26 formed by protruding a cover material around the recess panel 25, and the cover material. A rivet 27 is formed so as to protrude toward the outer surface of the lid, and an opening tab 28 is fixed by riveting the rivet 27. The opening tab 28 has an opening tip 29 by pushing and tearing at one end and a holding ring 30 at the other end. In the vicinity of the rivet 27, on the opposite side of the score 24, a break starting score 31 that is discontinuously arranged with the score 24 is formed.
The specific examples shown in FIGS. 3 and 4 are so-called full open types, but of course, they can also be applied to stay-on-tab type easy open lids.

(Use)
Since the press-molded can and lid of the present invention are excellent in resistance to sulfur discoloration, they can be suitably filled with contents that may generate hydrogen sulfide such as seafood, meat, and vegetables, It is effectively prevented that the adhesiveness of the thermoplastic resin layer is impaired even when it is subjected to steaming or retort sterilization after filling with such contents.

  For Examples and Comparative Examples, manufacture of redrawn cans, peel strength measurement of inner organic resin coating layer after retort treatment, processing adhesion evaluation, steaming test, sulfur discoloration evaluation in actual can storage test, film float evaluation, corrosion Evaluation was performed as follows.

(1) Manufacture of redrawn can and evaluation of processing adhesion After punching a resin-coated surface-treated steel sheet into a circular blank having a diameter of 147.5 mm, drawing with a drawing ratio of 1.51 is performed, and further a drawing ratio of 1.32 Were redrawn, bottom panel processed, beaded and trimmed to form a redrawn can with a can inner diameter of 74.1 mm, a can height of 47 mm and an internal volume of 183 ml. The can after the molding was observed, and the state of floating and peeling of the organic resin coating layer was evaluated by the following evaluation points.
Score 5: No abnormalities
Rating 4; Floating occurrence of resin coating with a diameter of less than 0.2 mm below 5% length of flange portion Rating 3; Floating occurrence rating of resin coating with a diameter of less than 0.5 mm on flange portion 2; 0 on flange portion or can body portion .Rising occurrence of resin coatings with a diameter of 5 mm or more 1; Resin coating peeling on flange or can body

(2) Steaming test The 2-piece can used for the processing adhesion test was used, and water vapor was sprayed from the top of the empty can for 30 minutes. After cooking, the can was observed, and the floating and peeling of the organic resin coating layer were evaluated according to the following evaluation points.
Score 5: No abnormalities
Rating 4; Floating occurrence of resin coating with a diameter of less than 0.2 mm below 5% length of flange portion Rating 3; Floating occurrence rating of resin coating with a diameter of less than 0.5 mm on flange portion 2; 0 on flange portion or can body portion .Rising occurrence of resin coatings with a diameter of 5 mm or more 1; Resin coating peeling on flange or can body

(3) Real can storage test Using two-piece cans used for processing adhesion test, after filling with salmon or beef, aluminum easy-open lid or easy-open lid made of the same organic resin-coated surface-treated steel plate as the can body After double winding, retort treatment was performed. Thereafter, after being stored in a constant temperature room at 37 ° C. for 1 year, the can was opened and the inner surface of the can was observed with the naked eye to evaluate sulfur discoloration, the state of the organic resin coating layer, and internal corrosion.
In the case of salmon meat, 175 g of meat and 1.9 g of salt are filled and wound, and then retort treatment is performed at 115.5 ° C. for 90 minutes, and in the case of beef, 170 g of meat is filled and wound and then 113 ° C. For 70 minutes.

(4) Peel strength measurement of the organic resin coating layer on the inner surface of the can body after retort treatment After performing filling, lid tightening and retort treatment in the same manner as the actual can storage test, the can was opened and the contents removed and washed In the organic resin coating layer on the inner surface of the inner can body, linear cuts are made at intervals of 15 mm width in the can height direction, a part of the organic resin coating layer is peeled off, and then the organic resin coating layer is canned using a tensile tester The film was peeled in the direction of 180 ° in the height direction at a speed of 5 mm / min, and the peel strength was measured. When the tensile strength at break of the organic resin coating layer was weak and it broke before peeling, a metal foil tape coated with an adhesive was attached to the organic resin coating layer and the measurement was performed with the breaking strength increased.

Example 1
A cold rolled steel sheet having a thickness of 0.18 mm and a tempering degree of DR8 is used as a metal plate, and tin is 0.8 g / m ² thick on the surface that becomes the inner surface of the can and a tin thickness of 1 on the surface that becomes the outer surface of the can. .3g / ^{m 2} and plated at the same time, after washing, followed by the surface to be the inner surface of the can by a conventional method, after the zinc thickness 0.10 g / ^{m 2} plating was washed and subjected to reflow treatment of the tin. Next, a 2% aqueous solution of γ-aminopropyltrimethoxysilane was used on both sides of this plated steel sheet, and the Si amount per side was applied to 8 mg / m ² and dried at 80 ° C. to obtain a surface-treated steel sheet. .
After heating the surface-treated steel sheet thus obtained to 220 ° C., the surface of the inner surface of the can is a blend resin of 82 wt% polyethylene terephthalate / isophthalate (copolymerization ratio 15 mol%) resin and 18 wt% ionomer resin to a thickness of 20 μm. It was extrusion coated in the molten state and quenched.
The outer surface of the can was coated with an epoxy acrylic water-based paint so as to have a thickness of 3 μm, baked and dried at 200 ° C., applied with printing and finishing varnish, and baked and dried at 180 ° C. Using this double-sided organic resin-coated surface-treated steel sheet, a redrawn can was produced and subjected to a heat treatment at 210 ° C. for 1.5 minutes (can peak temperature 205 ° C., peak time 0.5 seconds). The peel strength measurement and processing adhesion evaluation of the organic resin coating layer on the inner surface of the upper part of the can body after the retort treatment of the two-piece can obtained in this way, evaluation of the peeling of the organic resin during steaming, filling with salmon meat and winding an aluminum easy open lid A tightened actual can storage test (evaluation of sulfide discoloration, film floating and corrosion) was conducted. The results are shown in Tables 1 and 2.

(Examples 2 to 4, Comparative Example 1)
In Examples 2 to 4 and Comparative Example 1, a two-piece can was produced in the same manner as in Example 1 except that the amount of inner surface tin plating was changed to the values shown in Table 1, and various evaluations were performed. The results are shown in Tables 1 and 2.

(Example 5)
Example 5 produced a two-piece can in the same manner as in Example 1 except that the inner surface tin plating amount, surface treatment type and thickness, and inner surface organic resin type were changed to those shown in Table 1, and various evaluations were made. Went. The results are shown in Tables 1 and 2.

(Examples 6 and 7)
In Examples 6 and 7, a two-piece can was produced in the same manner as in Example 1, except that the amount of inner surface tin plating, the type of surface treatment was water-soluble phenol resin treatment, and the thickness was changed to that shown in Table 1. Various evaluations were performed. The results are shown in Tables 1 and 2.

(Examples 8 to 11 and Comparative Examples 2 to 5)
In Examples 8 to 11 and Comparative Examples 2 to 5, the amount of tin on the inner surface and the amount of zinc in the tin-zinc alloy were changed to those shown in Table 1, filled with beef, and made of the same resin-coated steel plate as the can body A two-piece can was produced in the same manner as in Example 1 except that the open lid was wound, and various evaluations were performed. The results are shown in Tables 1 and 2.

(Examples 12 to 14, Comparative Examples 6 and 7)
In Examples 12 to 14 and Comparative Examples 6 and 7, a two-piece can was produced in the same manner as in Example 1 except that the amount of inner surface tin plating and the surface treatment thickness were changed to the amounts shown in Table 1, and various evaluations were performed. It was. The results are shown in Tables 1 and 2.

(Examples 15 to 17, Comparative Examples 8 and 9)
Examples 15 to 17 and Comparative Examples 8 and 9 were the same as in Example 1 except that the amount of inner surface tin plating, the type of surface treatment was Zr-containing water-soluble phenol resin treatment, and the C amount was changed to that shown in Table 1. Then, a two-piece can was manufactured and various evaluations were performed. The results are shown in Tables 1 and 2.

(Example 18)
Example 18 produced a two-piece can in the same manner as in Example 1 except that the amount of inner surface tin plating, the type and thickness of surface treatment, and the type of inner surface organic resin coating were changed to those shown in Table 1, and various evaluations were made. Went. The results are shown in Tables 1 and 2.
The electrolytic zirconium oxide treatment was performed after preparing an aqueous solution of zirconium zirconium hydrofluoride 6.25 g / L, potassium nitrate 0.5 g / L, and sodium perborate 0.05 mol / L and adjusting the pH to 6.0. Then, the plate to be treated was immersed in the solution, and the sample was used as a cathode, and intermittent electrolysis was performed at a current density of 0.6 A / dm ² to obtain a zirconium oxide treated film of 20 mg / m ^{2 in} terms of metal Zr.

(Example 19)
In Example 19, the amount of inner surface tin plating, the type and thickness of surface treatment, and the type of inner surface organic resin coating were changed to those shown in Table 1, except that cup heating was not performed. Were manufactured and evaluated in various ways. The results are shown in Tables 1 and 2.
Incidentally, in the combined treatment of electrolytic zirconium oxide treatment and silane coupling agent treatment, first a zirconium oxide treated film was obtained in the same manner as in Example 18, and then a 2% aqueous solution of γ-aminopropyltrimethoxysilane on both sides. Was applied at 5 mg / m ² per side and dried at 80 ° C. to obtain a composite treated film.

(Example 20)
Example 20 changes the amount of inner surface tin plating, the type and thickness of surface treatment, and the type of inner surface organic resin coating to those shown in Table 1, and the two-piece can is formed in the same manner as in Example 1 except that cup heating is not performed. Manufactured and evaluated in various ways. The results are shown in Tables 1 and 2.
The composite treatment of electrolytic zirconium oxide treatment and water-soluble phenol resin treatment was carried out in the same manner as in Example 18, after obtaining a zirconium oxide treatment film, followed by water-soluble phenol resin treatment to obtain a composite treatment film. It was.

(Example 21)
Example 21 produced a two-piece can in the same manner as in Example 1 except that the amount of inner surface tin plating, the type and thickness of surface treatment, and the type of inner surface organic resin coating were changed to those shown in Table 1, and various evaluations were made. Went. The results are shown in Tables 1 and 2.
The electrolytic titanium oxide treatment was performed by preparing an aqueous solution of hydrofluoric acid 0.01 g / L, 75% phosphoric acid 0.20 g / L, and 20% zirconium hydrofluoric acid 1.30 g / L. The plate to be treated was immersed, and the sample was used as a cathode, and intermittent electrolysis was performed at a current density of 5 A / dm ² to obtain a titanium oxide treated film of 25 mg / dm ^{2 in} terms of metal Ti.

(Comparative Example 10)
In Comparative Example 10, a two-piece can was produced in the same manner as in Example 1 except that the amount of inner surface tin plating, the type of surface treatment, and the thickness were changed to those shown in Table 1, and various evaluations were performed. The results are shown in Tables 1 and 2.
The phosphoric acid treatment was carried out by cathodic electrolysis of the treated plate in an aqueous solution of sodium phosphate 30 g / L at 50 ° C.

(Comparative Example 11)
In Comparative Example 11, a two-piece can was produced in the same manner as in Example 1 except that the amount of inner surface tin plating, the type of surface treatment, and the thickness were changed to those shown in Table 1, and various evaluations were performed. The results are shown in Tables 1 and 2.
The molybdate treatment was performed by cathodic electrolysis of the treated plate in an aqueous solution of 10 g / L sodium molybdate and 3 g / L sodium hydrogen phosphate at 60 ° C.

(Comparative Example 12)
In Comparative Example 12, a two-piece can was produced in the same manner as in Example 1 except that the amount of inner surface tin plating, the type and thickness of the surface treatment were changed to those shown in Table 1, and various evaluations were performed. The results are shown in Tables 1 and 2.
Incidentally, polyacrylic acid treatment, were treated by immersing the treated plate polyacrylic acid _{75 g} / L, an aqueous solution of _{H 2} TiF 6 40g / L.

(Comparative Example 13)
In Comparative Example 13, a two-piece can was produced in the same manner as in Example 1 except that the amount of inner surface tin plating, the type of surface treatment, and the thickness were changed to those shown in Table 1, and various evaluations were performed. The results are shown in Tables 1 and 2.
In the triazine thiol treatment, the plate to be treated is immersed in a 1% aqueous solution of 1,3,5-triazine-2,4,6-trithiol monosodium at 20 ° C. and treated at 0.3 V for 2 minutes as a cathode. went.

(Examples 22 and 23, Comparative Examples 14 and 15)
Examples 22 and 23 and Comparative Examples 14 and 15 were the same as in Example 1 except that the amount of inner surface tin plating, the type of inner surface organic resin coating, and the cup heating temperature were changed to those shown in Table 1. Manufactured and evaluated in various ways. The results are shown in Tables 1 and 2.

(Example 24)
In Example 24, the amount of inner surface tin plating and the type of inner surface organic resin coating were changed to those shown in Table 1, the following coating method was changed, and a two-piece can was performed in the same manner as in Example 1 except that cup heating was not performed. Were manufactured and evaluated in various ways. The results are shown in Tables 1 and 2.
The inner surface organic resin used was a film cast on a cooled roll, and this film was corona-treated (voltage 200 V, current 2 A / 25 cm, 5 m / min treatment speed) and then heated to 220 ° C. in advance. An organic resin-coated surface-treated steel sheet was obtained by heat laminating on the surface-treated steel sheet.

樹脂の種類
Ａ：ＰＥＴ／ＩＡ１５モル（８２ｗｔ％）とアイオノマー樹脂（１８ｗｔ％）のブレンド樹脂
Ｂ：ＰＥＴ／ＩＡ１５モル
Ｃ：ＰＥＴ／ＩＡ１１モル（８２ｗｔ％）とポリプロピレン樹脂（１８ｗｔ％）のブレンド樹脂
Ｄ：ＰＥＴ／ＩＡ２０モル（８２ｗｔ％）
Ｅ：ＰＥＴ／ＩＡ１５モル（５４ｗｔ％）とＰＢＴ／ＩＡ１０モル（３６ｗｔ％）とアイオノマー樹脂（１０ｗｔ％）のブレンド樹脂
Ｆ：ＰＥＴ／ＩＡ８モル（８２ｗｔ％）とアイオノマー樹脂（１８ｗｔ％）のブレンド樹脂
Ｇ：ＰＢＴ／ＩＡ２０モル（９０ｗｔ％）とポリプロピレン樹脂（１０ｗｔ％）のブレンド樹脂

Resin type A: Blend resin D of PET / IA 15 mol (82 wt%) and ionomer resin (18 wt%) B: PET / IA 15 mol C: Blend resin D of PET / IA 11 mol (82 wt%) and polypropylene resin (18 wt%) : PET / IA 20 mol (82 wt%)
E: Blend resin of PET / IA 15 mol (54 wt%), PBT / IA 10 mol (36 wt%) and ionomer resin (10 wt%) F: Blend resin G of PET / IA 8 mol (82 wt%) and ionomer resin (18 wt%) : PBT / IA 20 mol (90 wt%) and polypropylene resin (10 wt%) blend resin

It is a figure which shows an example of the cross-sectional structure of the resin coating surface treatment steel plate used for this invention. It is a side view which shows an example of the press molding can of this invention. It is a top view which shows an example of the cover material of this invention. It is a side view of the lid | cover material shown in FIG.

Claims (13)

Press molding formed by press-molding a resin-coated surface-treated steel sheet in which a tin plating layer, a tin-zinc alloy layer, a non-chromium surface treatment layer, and a thermoplastic resin layer are formed in order from the steel plate side on the steel plate on the inner surface of the can. A tin amount of the tin plating layer is 0.8 g / m ² or more, a Zn amount in the tin-zinc alloy layer is 0.06 to 0.5 g / m ² , and a can after retorting A press-molded can characterized by having a peel strength of a thermoplastic resin layer at the upper portion of the can body having a peel strength of 100 g / 15 mm width or more. Sn content of the tin plating layer, press molding can of claim 1 wherein the 0.8~12g / ^{m 2.}   The press-molded can according to claim 1 or 2, wherein the thermoplastic resin layer is formed of a polyester-based thermoplastic resin having a melting point of 200 to 235 ° C.   The non-chromium surface treatment layer comprises at least one of a surface treatment layer mainly composed of a silane coupling agent, a surface treatment layer made of a water-soluble phenol-based compound, and an inorganic surface treatment layer containing Zr and / or Ti. 4. A press-molded can according to any one of items 3 to 3. 5. The press-molded can according to claim 4, wherein the amount of Si in the surface treatment layer containing the silane coupling agent as a main component is ² to 50 mg / m ² . The press molding can according to claim 4, wherein the C content of the surface treatment layer by the water-soluble phenol compound is 0.8~50mg / ^{m 2.}   The press-molded can according to claim 4, wherein the inorganic surface treatment layer is formed by intermittent cathodic electrolysis using an aqueous solution mainly composed of Zr and / or Ti, O, and F.   The surface treatment layer is formed by performing an inorganic surface treatment containing Zr and / or Ti, and then performing a surface treatment mainly using a silane coupling agent or a surface treatment with a water-soluble phenol compound. A press-molded can according to any one of claims 1 to 7.   The press-molded can according to any one of claims 3 to 8, wherein the polyester-based thermoplastic resin is a copolymer resin of polyethylene terephthalate and / or a copolymer resin of polybutylene terephthalate.   The press-molded can according to any one of claims 3 to 9, wherein the polyester-based thermoplastic resin layer is formed by blending a polyester-based thermoplastic resin with a polyolefin.   The press-molded can according to any one of claims 3 to 10, wherein the polyester-based thermoplastic resin is subjected to corona treatment.   Prior to the retort treatment, heat treatment is performed in a range of Tm-40 ° C to Tm + 10 ° C (Tm: melting point of a base thermoplastic resin used for a thermoplastic resin layer bonded to a surface treatment layer). The press-molded can according to any one of 11. In order from the steel sheet side on the steel sheet is at least the can inner surface side, Sn amount is 0.8 g / ^{m 2} or more of the tin plating layer, a tin zinc alloy layer of Zn amount 0.06~0.5g / ^{m 2,} non-chromium surface A lid comprising a treated layer and a resin-coated surface-treated steel sheet formed with a polyester thermoplastic resin layer having a melting point of 200 to 235 ° C.

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