JP2009046752A - Steel sheet for container material with less load on environment and its manufacturing method, and laminate steel sheet for container material with less load on environment and pre-coat steel sheet for container material using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steel sheet for a container material with less load on environment having excellent adhesiveness to a laminate film or an organic resin coating film such as paint equivalent to the conventional steel sheet for a container material subjected to chromate treatment and excellent iron-dissolution resistance after dent impact, and also to provide its manufacturing method for preventing fluoride or nitrate nitrogen compound from being discharged in a manufacturing step. <P>SOLUTION: In the film laminate steel sheet for the container material or a coated steel sheet for a container material, a tin layer or an iron-tin alloy layer is formed on the steel sheet, and a chromium-free adhesive substrate-treatment layer consisting of tungsten compound which does not contain fluorine or nitrate nitrogen is formed thereon. The thickness of a tin oxide layer present on the tin layer or the iron-tin alloy layer on the steel sheet is ≤3.5 mc/cm<SP>2</SP>in the measurement by the electrolytic stripping method. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a surface-treated metal material and a surface treatment method thereof, and more specifically, a steel plate for a container material that does not use a treatment liquid containing chromium, fluorine, and nitrate nitrogen when the steel plate is subjected to a base treatment, and Laminated steel sheet and container for container material with low environmental impact, excellent in its production method, adhesion to organic resin coatings such as laminate film or paint using the same, and iron elution resistance after dent impact The present invention relates to a precoated steel sheet for materials.

  Treatment with chromate treatment, phosphate treatment, silane coupling agent as treatment to improve the adhesion between organic materials and metal materials such as steel plate, zinc-based plated steel plate, zinc alloy plate, tin-based plated steel plate, aluminum alloy plate Etc. are conventionally known. Among these, chromate treatment has been widely used in fields such as home appliances, building materials, vehicles, and metal containers due to its excellent corrosion resistance and adhesion, but when it is discarded, hexavalent chromium, which is a harmful substance, is eluted into the soil and contaminated. As the possibility of doing so has been pointed out, it is already in the direction of eliminating chromate treatment mainly in Europe.

In the case of metallic materials for containers, hexavalent chromium remains in the coating when tin-plated steel sheets are subjected to cathodic electrolysis in an aqueous solution of sodium dichromate, or the steel sheets are subjected to cathodic electrolysis in an aqueous solution of chromic anhydride containing fluoride. This type of chromate treatment is used, but even in the case of chromate treatment in which the treatment layer does not contain hexavalent chromium, the treatment liquid itself contains hexavalent chromium. It is necessary to perform drainage and exhaust treatment. From the viewpoint of environmental load, surface treatment that does not contain hexavalent chromium in the treatment liquid is preferable.
In addition, fluorine, boron, nitrate nitrogen, etc. are not preferable from the viewpoint of environmental burden, and the emission standards will be strengthened in the future. It is desirable not to.

Therefore, one way to reduce the burden on the environment is to make it chrome-free. As a chromium-free surface treatment for container materials, the tin-plated surface obtained by processing a tin-plated steel sheet has an organic-inorganic composite film composed of an organic compound mainly composed of carbon and an inorganic phosphorus compound. As an example of a surface treatment method for an excellent tin-plated steel can, Patent Document 1 includes at least one of phosphate ions, a tungsten compound, and a titanium compound as a surface treatment solution before painting / printing of an aluminum can or tinplate DI can. Patent Document 2 is known as an example of a DI can surface treatment liquid containing an oxidizing agent, at least one of hydrofluoric acid and fluoride.
Japanese Patent Laid-Open No. 11-264075 JP 7-48677 A

  Conventionally, metal cans for beverage cans and food cans have generally been subjected to paint baking treatment on the inner and outer surfaces after canning, but in recent years as metal materials for beverage cans or food cans More and more, steel plates obtained by thermally laminating a film on a steel plate in advance, and precoated steel plates obtained by performing printing and baking coating on a steel plate in advance have been increasingly used.

  In the can manufacturing process by DI molding and DRD molding, the ironing force works on the can wall. Is easy to peel off the resin film. In addition, in the heat sterilization treatment (retort treatment) performed after filling the contents, water penetrates into the resin film under high temperature and high pressure, and the adhesion tends to be lowered. It may lead to rusting.

  The problems to be solved by the present invention are excellent in adhesion to an organic resin film such as a laminate film or paint equivalent to a conventional steel plate for a container material subjected to chromate treatment, and iron dissolution resistance after dent impact. Another object is to provide a chromate-free type steel plate for container materials.

  In addition, the treatment liquid containing fluoride and nitrate nitrogen as in the case of the chromium compound requires a waste water treatment facility in the case of the waste water treatment, and needs to be detoxified with a great deal of cost and time. From the environmental point of view, it is more desirable that the treatment liquid does not contain fluoride or nitrate nitrogen compounds. It is another problem to be solved by the present invention to provide a chromate-free steel sheet for container materials that does not contain fluoride and nitrate nitrogen, which have a low operating cost load and low environmental burden.

  In order to solve the above-mentioned problems, the present inventors have intensively studied a pre-surface treatment method before chromate-free pretreatment when using a tin steel plate and a chromate-free pretreatment method optimal for the tin steel plate. It has been found that a chromate-free type steel plate for container materials that does not contain fluoride and nitrate nitrogen compounds with less capital investment load, operation cost load, and environmental load can be obtained.

That is, the present invention
(1) A tin layer or an iron-tin alloy layer is formed on the steel plate, and further, a chromium-free adhesion base treatment layer made of a tungsten compound not containing fluorine or nitrate nitrogen is formed on the steel plate. A steel plate for a container material having a low environmental load, wherein the tin oxide layer thickness present on the tin layer or the iron-tin alloy layer is 3.5 mc / cm ² or less as measured by electrolytic stripping;
(2) A method for producing a steel plate for a container material having a low environmental impact as described in (1), wherein a tin layer or an iron-tin alloy layer is formed on the steel plate, and then in a sodium hydrogen carbonate solution. By performing cathodic electrolysis, the tin oxide layer on the tin layer or the iron-tin alloy layer is reduced to 3.5 mc / cm ² or less as measured by the electrolytic stripping method, and is then composed of a tungsten compound containing no fluorine or nitrate nitrogen. A method for producing a steel plate for a container material having a low environmental impact, characterized by performing a chromium-free adhesion base treatment,
(3) A method for producing a steel plate for a container material with a low environmental load described in (1), wherein a tin layer or an iron-tin alloy layer is formed on the steel plate and then immersed in a sulfuric acid solution. The tin oxide layer or the tin oxide layer on the iron-tin alloy layer is reduced to 3.5 mc / cm ² or less as measured by the electrolytic stripping method, and then a chromium-free adhesion base treatment made of a tungsten compound containing no fluorine or nitrate nitrogen is performed. A method for producing a steel plate for a container material having a low environmental impact,
(4) Ammonium tungstate aqueous solution is applied or dipped onto the tin layer or iron-tin alloy layer, and then dried to form a chromium-free adhesive undercoat made of a zirconium compound on the tin layer or iron-tin alloy layer. (2) or (3), the method for producing a steel plate for a container material having a low environmental load,
(5) A laminated steel sheet for container materials and a coated pre-coated steel sheet for container materials, characterized by using the steel sheet for container materials having a low environmental load described in (1),
It is.

  The container material steel plate of the present invention, which has a low environmental impact, has the same adhesion to a conventional chromate-treated steel plate for container material as that of an organic resin film such as a laminate film or paint, and resistance to dent impact. Because it has iron-eluting properties and does not contain chromium compounds, fluorides, and nitrate nitrogen in its processing solution, it performs the detoxification process required when draining these substances with high environmental impact. This is a chromate-free steel plate for container materials that has less environmental impact from the viewpoint of the environment, and has extremely high industrial value because of its excellent food safety and industrial productivity.

The steel plate for container material with a low environmental load of the present invention has a tin plate layer or an iron-tin alloy layer at least on the surface of the steel plate which is the inner surface of the can, and further has fluoride or nitric acid thereon. Characterized in that a chromium-free adhesion base treatment layer made of a tungsten compound containing no reactive nitrogen is formed, and in particular, before performing the chromium-free adhesion base treatment, cathodic electrolysis in a sodium hydrogen carbonate solution, or By performing the sulfuric acid immersion treatment, the tin oxide layer or the tin oxide layer on the iron-tin alloy layer is reduced to 3.5 mc / cm ² or less as measured by electrolytic stripping.
The best mode for carrying out the invention will be described below.

<Steel plate>
The type of the steel plate used in the present invention is not particularly limited, and may be the same as the tin plate or TFS original plate that has been conventionally used for container materials.

<Tin plating>
Plating types that can be used for food applications must satisfy food safety and hygiene, manufacturability, etc., and practically usable plating types include tin, aluminum, and nickel as suitable candidates. It is done. In the chromium-free steel sheet for container materials used as a container material steel sheet with low environmental impact in the present invention, the reason for using tin plating is that it has a high track record of use in canned applications and has no problems in food safety and hygiene, and is excellent in corrosion resistance. For example, excellent formability, and relatively inexpensive as compared with other plating.

The tin-plated steel sheet used in the present invention may be a normal electroplated tinplate steel sheet and may be subjected to an iron-tin alloying treatment (reflow treatment). The tin plating amount is preferably in the range of 0.5 to 12.0 g / m ² from the viewpoint of suppressing iron elution in the dent portion after film lamination or coating. When the tin plating amount is less than 0.5 g / m ² , the iron elution amount after dent increases and the corrosion resistance decreases, which is not preferable. Moreover, even if the tin plating amount exceeds 12.0 g / m ² , there is no particular problem in performance. However, in the manufacturing process, it tends to adhere to and accumulate on rolls, etc., which may cause pressing. This is not preferable because the plating cost is higher than necessary.

<Tin oxide removal treatment>
The steel plate for a container material having a low environmental load according to the present invention is formed by forming a chromium-free adhesion base treatment layer made of a tungsten compound not containing fluorine or nitrate nitrogen on a tin plating layer or an iron-tin alloy layer. Although it is characteristic, since the tin oxide layer exists on the surface of the plated plate as it is, it is difficult to uniformly deposit the tungsten compound on the tin plating layer or the iron-tin alloy layer.

  If the adhesion of the tungsten compound on the tin-plated layer or iron-tin alloy layer is not uniform, uneven adhesion will occur with the laminated film or paint, and when steel sheets after film lamination or coating are canned When the film or paint is peeled off, or when a dent impact is applied to the can body, the film is liable to be peeled off.

Therefore, the inventors investigated the influence of the amount of tin oxide remaining in the tin-plated steel sheet on the film peel strength of the film-laminated tin-plated steel sheet on which the tungsten compound was pretreated. The result is shown in FIG. The laminated steel plate used at this time is a chromate-free base-treated steel plate in which ammonium tungstate is immersed in a 2.8 g / m ² tin-plated steel plate on one side, and an unstretched copolyester film having a thickness of 20 μm on both sides of the steel plate. Was obtained by heat laminating.
The peel strength of the film is the result of measurement using a film-laminated steel sheet placed in a retort steam kettle and subjected to retort sterilization at 125 ° C. for 90 minutes.
The amount of tin oxide in the tin-plated steel sheet is the amount of tin oxide measured by the electrolytic stripping method before the base treatment of the tin-plated steel sheet that has been appropriately treated to remove tin oxide from the untreated tin-plated steel sheet.

As can be seen from FIG. 1, the peel strength is stable until the tin oxide amount on the tin plating is 3.5 (mc / cm ² ), but the tin oxide amount is 3.5 (mc / cm ² ). When it exceeds cm ² ), it can be seen that the peel strength of the film rapidly decreases.
When the amount of tin oxide on the tin plating is 3.5 (mc / cm ² ) or less, it is considered that there is a portion with a small amount of tin oxide. Are considered to be firmly bonded. On the other hand, when the tin oxide amount on the tin plating exceeds 3.5 (mc / cm ² ), the entire surface of the tin plating is covered with the tin oxide layer, so that it easily peels from the fragile tin oxide layer. Conceivable.

From the above results, in order to stabilize the adhesion state of the tungsten compound on the tin plating layer or iron-tin alloy layer, the tin oxide layer of the tin-plated steel sheet was measured by electrolytic stripping immediately before the tungsten adhesion treatment. The removal process is performed to a level of 3.5 mc / cm ² or less. If the thickness of the tin oxide layer exceeds 3.5 mc / cm ² as measured by the electrolytic stripping method, it tends to cause cohesive failure from the remaining tin oxide layer when processing or impact is applied, and the adhesion of the film or paint is improved. Since it falls remarkably, it is not preferable.

  As a method for removing the tin oxide layer formed on the tin plating layer or the iron-tin alloy layer, the cathodic electrolysis treatment in a sodium hydrogen carbonate solution is performed, and the tin oxide layer is reliably removed in a short time. And there is almost no dissolution of tin, which is the most preferable method.

  From the viewpoint of improving the adhesion of films and paints, it is preferable that the tin oxide layer is not present at all. However, even if the tin oxide layer is completely removed, the outermost surface of the tin is oxidized as soon as there is some oxygen. It is difficult to carry out film lamination or coating with no tin oxide on the surface of the tin plating, which is difficult with ordinary equipment, and even if it can be realized, it is not a preferable method because of high manufacturing costs.

If the tin oxide layer on the tin plating is removed to 0.01 mc / cm ² , adhesion substantially equivalent to the state without the tin oxide layer can be obtained, so that the tin oxide layer has a thickness of 0.01 mc / cm ² to 3 The range is preferably 0.5 mc / cm ² .

  As a method of removing the tin oxide layer formed on the other tin plating layer or iron-tin alloy layer, a method of immersing in a sulfuric acid aqueous solution is preferable. If washing is not carried out with water, the sulfuric acid content remains and the coating film adhesion may deteriorate, so care must be taken.

  In the electrolytic stripping method, the constant current electrolysis principle is applied to perform constant current electrolysis of the test piece, the potential change of the test piece accompanying the electrolytic stripping is recorded on a pen recorder, and the electrolysis time-potential curve is used to This is a method of measuring the amount, that is, the amount of surface tin adhesion and the oxide film.

<Tungsten compound treatment>
In the present invention, the measurement by an electrolytic stripping method is performed by cathodic electrolysis in a sodium hydrogen carbonate solution or by immersing a tin oxide layer on an iron-tin alloy layer on a tin-plated steel sheet or in a sulfuric acid solution. A chromium-free adhesion base treatment layer made of a tungsten compound not containing fluorine or nitrate nitrogen is formed after the tin oxide layer is removed to a level of 3.5 mc / cm ² or less. The reason for using as a surface treatment agent is that the surface of the tin-plated steel sheet is coated with a hydrated oxide of tungsten, so that the hydrated oxide of tungsten and the hydroxyl group contained in the resin coating layer are covered in the same manner as the chromate treatment. It aims at improving the adhesiveness with the resin film by generating a hydrogen bond.

  The inventors have studied the suitability of various metal oxides as a chromium-free adhesive base treatment agent in anticipation of the same effect as a tungsten compound. It has been found that it is excellent in adhesion (especially secondary adhesion after retorting).

  As a method for forming a chromium-free adhesive base treatment layer comprising a tungsten compound containing no fluorine or nitrate nitrogen, a coating method using a normal roll coater, a roll or an air knife after dipping a steel plate in a treatment solution, etc. There is a dipping method that drops excess liquid. In the conventional chromate treatment, fluoride or nitric acid is sometimes added to the treatment liquid for the purpose of activating the tin plating surface containing tin oxide. In the chromium-free ground treatment of the present invention, the ground treatment is performed. By removing to a level below which there is no influence of the tin oxide layer, it is possible to form a uniform chromium-free ground treatment layer with good adhesion to the plating layer without adding fluoride or nitric acid to the treatment liquid Can do.

If the treatment tank and piping system are used for treatments other than chromium-free ground treatment, fluorine or nitrate nitrogen may be inevitably mixed even if the treatment process is switched to chromium-free ground treatment. but as the level which does not contain fluorine or nitrate nitrogen, preferably fluorine or nitrate nitrogen in the chrome-free bonding undercoat treatment layer is 5 mg / m ² or less, if the 5 mg / m ² or less of inclusion levels It can be said that it is substantially not treated with fluorine or nitrate nitrogen, and the treatment liquid wastewater treatment can also be handled by the conventional wastewater treatment facility for electrolytic chromic acid treatment, and the load on the wastewater treatment equipment is electrolytic chromium It is far less than the acid treatment liquid and the waste liquid treatment cost is negligible.

  As for the method of depositing the tungsten compound by coating, an aqueous solution of ammonium tungstate is most preferable as the treatment liquid from the viewpoints of stability and ease of handling.

According to the study by the present inventors, it is known that the adhesion amount of the tungsten compound is less than 10 mg / m ^{2 by} weight in terms of tungsten after drying. It is preferable to apply the treatment liquid so that the adhesion amount in terms of tungsten is 10 mg / m ² or less. After the treatment liquid is applied on the tin-plated steel sheet, it is preferably dried to evaporate water. The drying method may be natural drying or heat drying.

Through the examples and comparative examples, each evaluation test was performed as follows.
1. Tin oxide layer thickness measurement Below, the tin oxide layer thickness shown in the examples and comparative examples is the removal of the tin oxide layer when the tin-plated steel sheet is used as the anode and the electrolysis peeling is performed at a constant current of 1 mA in 0.01% HBr aqueous solution. The amount of electricity was calculated from the electrolytic stripping time until it was applied, and displayed as the amount of electricity required for electrolytic stripping per unit area (mc / cm ² ).

2. Measurement of surface treatment agent adhesion amount Measurement of the surface agent adhesion amount after the surface treatment is performed by measuring the amount of metal in the metal oxide by fluorescent X-ray absorption spectrum measurement and displaying it as a converted value of the amount of adhered metal per unit area (mg / M ² ).

3. Film Laminate The front and back surfaces of the steel sheets prepared in Examples and Comparative Examples were heated to 225 ° C., 7 ° C. lower than the melting point of tin, and 20 μm thick unstretched copolymer polyester (terephthalic acid / isophthalic acid (weight ratio 88/12) on both sides) A film-laminated steel sheet was obtained by heat laminating a copolymer polyester (melting point: 228 ° C.) film composed of ethylene glycol with ethylene glycol at a laminating roll temperature of 150 ° C. and a sheet passing speed of 150 m / min and immediately cooling with water.

4). Retort treatment The film-laminated steel sheet was placed in a steam kettle for retort treatment and subjected to retort sterilization at 125 ° C for 90 minutes.

5). Film peel strength measurement Untreated and retort-treated film-laminated steel sheet is punched into a shape as shown in FIG. 2 using a dedicated punching die, and the width of the test piece is widened to a film with a width of 15 mm. Put a spear that reaches a steel plate surface of 30 mm or more.
A part of the steel sheet whose test piece width extends from 15 mm to 30 mm is cut using a special die press, leaving the film in the width direction, and the part with the test piece width of 15 mm is folded back toward the test piece width of 30 mm to obtain a film of 180. ° Make sure it is folded.
The 30 mm width portion of the test piece is inserted into a jig attached to the tensile tester, and the test piece width 15 mm portion is attached to the grip portion of the other tensile tester.
At a room temperature, a tensile speed of 20 mm / min. Measure the 180 ° peel strength of the film.

6). Can-making A wax-type lubricant is applied to both surfaces of a film-laminated steel sheet, and a disk having a diameter of 155 mm is punched out by pressing to obtain a shallow drawn cup. Subsequently, this shallow drawn cup was subjected to stretch ironing to obtain a cup having a cup diameter of 52 mm, a cup height of 138 mm, and an average plate thickness reduction rate of 18% at the side wall of the can. The cup was heat-treated at 215 ° C. for film distortion removal, and further subjected to heat treatment at 200 ° C. corresponding to printing baking to prepare a sample for can characteristic evaluation.

7). Canned product retort treatment A part of the canned product shown in the previous section was put into a steam bath for retort treatment, and retort sterilization treatment was performed at 125 ° C for 90 minutes.

8). Measurement of iron elution amount Fill the can with alkaline ion soft drink (for example, Aquarius, Coca-Cola Japan) to the top of the can, heat it in a constant temperature bath at 37 ° C for 7 days, take it out of the constant temperature bath, Discard Aquarius.
Next, a DuPont impact test (weight) was performed in a 5 ° C environment using separate cans at the steel plate rolling direction (0 ° direction) and 90 ° direction of the can wall at the can heights of 25 mm and 75 mm. Weight 1 kg, weight drop height 40 mm, impact indenter tip diameter Φ16 mm).
After the DuPont impact, the can was filled again with Aquarius and placed in a thermostat at 50 ° C. for 7 days, and then the amount of iron eluted in the aquarius in the can was measured by atomic absorption spectrometry.
The difference between the amount of iron in the Aquarius before filling and the amount of iron in the Aquarius after the dissolution test was defined as the amount of iron dissolved in one can (mg / L).
The number of tests was 3 cans for each DuPont impact position, and the total average (12 cans) of iron dissolution for 4 DuPont impact positions was taken as the iron dissolution per level.

9. Preparation of pre-coated steel sheet Using a bar coater on the surface of the steel sheet that had been subjected to the ground treatment in the examples and comparative examples, 25 g of single-sided epoxy paint (sizing varnish 10-031 manufactured by Dainippon Ink & Chemicals) was used. / M ² , followed by baking at 210 ° C. for 10 minutes in a baking drying oven.

10. Preparation of T-Peel Test Specimen for Coating Adhesion Evaluation Two coated surfaces of pre-coated steel plates are hot-pressed (200 ° C., 60 seconds, 1 MPa) with a hot press through a nylon adhesive film. After thermocompression bonding, the test piece is cooled, and then an adhesive test piece having a width of 10 mm and a length of 150 mm is cut out, and about 50 mm of the length of the adhesive test piece is peeled in advance as a grip allowance during the tensile test to produce a T peel test piece. To do.

11. Paint adhesion evaluation (T peel test)
The grip part that had been peeled in advance was sandwiched between the grip parts of a tensile tester, and the adhesive part 100 mm was pulled at room temperature at a pulling speed of 20 mm / min. To measure the T peel strength and evaluate the paint adhesion. Tables 1 and 2 show the surface treatment conditions of the steel sheets used in the examples and comparative examples.

  In Table 3, a film-laminated steel plate is produced using the plates treated under the conditions of Tables 1 and 2, and the initial adhesion strength of the film, the adhesion strength after the retort treatment, and the iron elution of the can product Indicates the amount.

  Table 4 shows pre-coated steel sheets prepared using the plates treated under the conditions in Tables 1 and 2, and the initial adhesion of T-peel specimens in which the coated surfaces are thermocompression bonded with a nylon adhesive film, and retort treatment. Indicates the adhesion strength afterwards.

Examples 1, 4, 5, 6, 7, 8, 9, 12, 13, 14, 15, and 16 were obtained by subjecting tin oxide on the surface of a tin-plated steel sheet to 0.7 (mc / cm) by cathodic electrolysis in an aqueous NaCO ₃ solution. ² ) The tin-plated steel sheet removed to the level of ( ² ) is further immersed in NH ₄ [H ₂ W ₁₂ O ₄₀ ] · nH ₂ O (5%) aqueous solution and dried to form a tungsten compound film on the tin plating. As shown in Tables 3 and 4, it can be seen that the film adhesion after initial and retort treatment as a film-laminated steel sheet and the paint adhesion as a pre-coated steel sheet are excellent.

Further, the amount of iron elution of the laminated steel plate cans of Examples 1, 4, 5, 6, 7, and 8 is less than that of the film laminated steel plate using the current mainstream tin-free steel plate shown in Comparative Example 4, It is good.
In addition, Examples 1, 4, 9, and 12 are examples tested using a newly-built circulation cell tank, and it was confirmed that no fluorine or nitrogen remained in the base material film. In Examples 5, 6, 7, 8, 13, 14, 15, and 16 using a circulation cell tank that has been used for other treatment baths in the past, the ground treatment liquid does not contain fluorine or nitric acid. Regardless, it was confirmed that a small amount of fluorine or nitrogen was present in the base material film. However, even if a small amount of fluorine or nitrogen is present in the base material film, there is no effect on the initial film adhesion as a film-laminated steel sheet and the film adhesion after retorting, and the paint adhesion as a pre-coated steel sheet. I couldn't.

In Examples 2, 3, 10, and 11, the tin-plated steel sheet obtained by immersing tin oxide on the surface of the tin-plated steel sheet in an aqueous H ₂ SO ₄ solution to a level of 1.5 to 3.5 (mc / cm ² ) was further obtained. This is a steel plate in which a plate is immersed in an aqueous solution of NH ₄ [H ₂ W ₁₂ O ₄₀ ] · nH ₂ O (5%) and then dried to form a tungsten compound film on tin plating. Thus, it can be seen that the film adhesion after initial and retort treatment as a film-laminated steel sheet and the paint adhesion as a pre-coated steel sheet are excellent.

  Moreover, the amount of iron elution of the laminated steel plate cans of Examples 2 and 3 is smaller and better than that of the film laminated steel plate using the current mainstream tin-free steel plate shown in Comparative Example 4.

In Comparative Examples 1 and 8, a steel plate obtained by immersing tin oxide on the surface of a tin-plated steel plate in an aqueous solution of H ₂ SO ₄ and removing the tin oxide layer up to 3.8 (mc / cm ² ) was obtained using NH ₄ [H ₂ W ₁₂ A steel plate in which a plate is immersed in an aqueous solution of O ₄₀ ] · nH ₂ O (5%) and then dried to form a tungsten compound film on the tin plating.
If the tin oxide layer remains more than 3.5 (mc / cm ² ), as shown in Tables 3 and 4, film adhesion after retorting as a film laminated steel sheet and paint adhesion as a precoated steel sheet You can see that it gets worse.

In Comparative Examples 2 and 9, an untreated tin-plated steel sheet (tin oxide layer 4.4 (mc / cm ² )) was immersed in an NH ₄ [H ₂ W ₁₂ O ₄₀ ] · nH ₂ O (5%) aqueous solution. Thereafter, the steel plate was dried to form a tungsten compound film on the tin plating.
As in Comparative Example 1, when the tin oxide layer remained more than 3.5 (mc / cm ² ), as shown in Tables 3 and 4, film adhesion after retorting as a film laminated steel sheet, and precoated steel sheet It can be seen that the adhesion of the paint becomes worse.

Comparative Examples 3 and 10 are examples of tin-plated steel sheets subjected to the current chromate treatment. As shown in Tables 3 and 4, it can be seen that the film-laminated steel sheet is excellent in initial and retort film adhesion. However, since the ground treatment is a chromate film, it is not a chromate-free steel sheet. In addition, in the chromate treatment, since the treatment liquid contains fluoride, the waste liquid needs to be detoxified. However, the fluoride remaining in the chromate film is 5 mg / m ² or less, and the retort It is a level that does not affect the film adhesion later.

Comparative Examples 4 and 11 are examples of current tin-free steel plates, and as shown in Tables 3 and 4, the film laminate steel plates are excellent in initial film adhesion and after film retort treatment. Because it has a chromate film, it is not a chromate-free steel sheet. Moreover, it turns out that there is much iron elution amount of canned goods compared with what uses a tin plating steel plate. In addition, since TFS contains fluoride in the treatment liquid, it is necessary to detoxify the waste liquid, but the fluoride remaining in the chromate film is 5 mg / m ² or less, and the retort It is a level that does not affect the film adhesion later.

In Comparative Examples 5 and 12, the tin-plated steel sheet in which tin oxide on the surface of the tin-plated steel sheet was subjected to cathodic electrolysis in an aqueous NaCO ₃ solution to a level of 0.7 (mc / cm ² ) was further removed in an aqueous solution of phosphate. It is a steel plate formed by electrolytic treatment to form a phosphorus compound film. As shown in Tables 3 and 4, it can be seen that the film adhesion after retort treatment as a film-laminated steel sheet and the paint adhesion as a pre-coated steel sheet deteriorate in the phosphorus compound film treatment.

In Comparative Examples 6 and 13, the tin-plated steel sheet in which tin oxide on the surface of the tin-plated steel sheet was subjected to cathodic electrolysis in an aqueous NaCO ₃ solution to a level of 0.7 (mc / cm ² ) was further treated with silane coupling to silane. It is a steel plate on which a coating film of a coupling agent is formed. As shown in Tables 3 and 4, it can be seen that in the silane coupling treatment, the film adhesion after initial and retort treatment as a film-laminated steel sheet and the paint adhesion as a pre-coated steel sheet are not so good.

In Comparative Examples 7 and 14, the tin-plated steel sheet in which tin oxide on the surface of the tin-plated steel sheet was subjected to cathodic electrolysis in an aqueous NaCO ₃ solution to a level of 0.7 (mc / cm ² ) was further added to Ce (NO ₃ ) ₃ ( 30 g / L) is a steel plate in which a cerium compound film is formed on tin plating by cathodic electrolysis.
As shown in Table 3 and Table 4, the film adhesion after initial and retort treatment as a film-laminated steel sheet is good, but nitric acid is contained in the chromate-free treatment chemical solution, so that nitrate nitrogen waste liquid treatment Since it is necessary, it is not desirable as a chromate-free treatment chemical.

It is a graph which shows the influence which residual tin oxide amount has on film peeling strength. It is explanatory drawing of the test piece for the film peeling strength measurement in an Example.

Claims (5)

A tin layer or an iron-tin alloy layer is formed on the steel plate, and further, a chromium-free adhesion base treatment layer made of a tungsten compound not containing fluorine or nitrate nitrogen is formed on the tin layer. Alternatively, a steel plate for a container material having a low environmental load, wherein the tin oxide layer thickness present on the iron-tin alloy layer is 3.5 mc / cm ² or less as measured by an electrolytic stripping method. A method for producing a steel plate for a container material having a low environmental load according to claim 1, wherein a tin layer or an iron-tin alloy layer is formed on the steel plate, and then cathodic electrolysis treatment in a sodium hydrogen carbonate solution. The tin oxide layer on the tin layer or the iron-tin alloy layer is reduced to 3.5 mc / cm ² or less as measured by the electrolytic stripping method, and then chromium-free adhesion comprising a tungsten compound containing no fluorine or nitrate nitrogen A method for producing a steel plate for a container material with low environmental impact, characterized by performing a ground treatment. A method for producing a steel plate for a container material having a low environmental load according to claim 1, wherein a tin layer is formed by dipping in a sulfuric acid solution after forming a tin layer or an iron-tin alloy layer on the steel plate. Alternatively, the tin oxide layer on the iron-tin alloy layer is reduced to 3.5 mc / cm ² or less as measured by electrolytic stripping, and then a chromium-free adhesion base treatment made of a tungsten compound not containing fluorine or nitrate nitrogen is applied. A method for producing a steel plate for container materials with a low environmental impact.   An aqueous solution of ammonium tungstate is applied or immersed on the tin layer or the iron-tin alloy layer, and then dried to form a chromium-free adhesive undercoat made of a zirconium compound on the tin layer or the iron-tin alloy layer. The method for producing a steel plate for a container material having a low environmental load according to claim 2 or 3.   A laminated steel sheet for container materials having a low environmental load, and a coated precoated steel sheet for container materials, characterized in that the steel sheet for container materials having a low environmental load is used.

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