JP2000263696A - Resin-coated steel plate for vessel and vessel employing this - Google Patents

Abstract

PROBLEM TO BE SOLVED: To give an excellent adhesion with a resin layer, and cause no contraction of a resin layer during welding, and also render a corrective coated film unnecessary by coating a non-orientated polyester resin layer on a surface treated steel plate with two layers consisting of the metal chrome layer of a lower layer and chrome hydration oxide layer of a lower layer on the surface of a steel plate. SOLUTION: A non-orientated polyester resin layer is coated on a surface treated steel plate formed with two layers consisting of a metal chrome layer of a lower layer and a chrome hydration oxide layer of an upper layer formed on the surface of a steel plate. A coating method of the resin layer employs a film lamination method in which one made by heat melting material resin pellets to subsequently be made into a film having a thickness of the order of 10-100 μm is press bonded on a surface treated steel plate being heated to a melting point of resin or higher, and an extrusion lamination method in which material resin pellets are heat melted to then be directly extruded for lamination onto the surface treated steel plate from a Ti-die. Also, in the use of filling a content having strong corrosion behavior, it is available to laminate a film with a primer consisting of a various kinds of resins coated in advance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a large-sized container for filling and storing a liquid seasoning, a detergent, a paint and the like, that is, a resin-coated steel plate used for a so-called 18-liter can, and a container using the same.

[0002]

2. Description of the Related Art A large welding container for filling and storing liquid seasonings, detergents, paints, and the like, so-called large square cans (18-liter cans) has conventionally been prepared by coating the inner surface with a double or triple paint. Although baked products have been used, there are problems such as that the process of baking paint is complicated, and that solvents and the like volatilize into the air during the baking of paint and pollute the environment. To resolve these issues,
A large square can coated with a biaxially stretched polyester film (JP-A-7-232731) is disclosed.

In this large rectangular can, the body, the canopy and the canopy are joined by double winding, and except for a welded portion (joining part of the body) extending in the height direction of the body, the inside of the body and the canopy and the canopy. Is coated with a biaxially stretched polyester film,
The welded portion is covered with a correction coating, and the canopy is provided with a washer for attaching a hand ring, which is joined by electric welding, and a biaxially stretched polyester film on the inner surface side of the canopy facing the washer is coated with the correction coating. It is characterized by being coated with a film.

Further, an opening for liquid injection is provided in the canopy, and the can is sealed by fitting a separately prepared lid. Conventionally, this opening is formed by piercing a canopy and projecting the opening end of the piercing portion upward, and projecting a ring-shaped base having an inner diameter of the piercing diameter and an outer diameter slightly smaller than the diameter of the lid. It was crimped on the part and formed as an opening. However, in recent years, for the purpose of cost reduction, as shown in FIG. 1, the opening end of the perforated portion of the canopy is protruded upward, and further protruded to the outside of the perforated portion, so that a portion that conventionally used a ring-shaped base is used. A rigorous molding method that directly molds the canopy directly from the canopy plate has been adopted.

[0005] However, in the large square can covered with the biaxially stretched polyester film, the biaxially stretched polyester film coated on the body member is baked with an external coating applied to display the contents or a joint portion of the body. The film shrinks due to heating during welding, and the correction coating of the welded portion becomes incomplete. In addition, the biaxially stretched polyester film at the hand ring attachment portion of the canopy is damaged by the embrittlement and shrinkage of the film due to heating during electric welding, and therefore needs to be covered with a correction coating film. further,
When severe forming of the canopy opening is performed, the biaxially stretched polyester film has high rigidity and low elongation, so that the film is torn or peeled off from the steel plate, and the canopy opening cannot be integrally formed.

[0006]

In the present invention, in order to solve the above-mentioned drawbacks of the prior art, the resin layer does not shrink when the outer surface coating film is baked, and the washer for attaching the hand ring of the canopy is electrically welded. The present invention provides a resin-coated steel plate for a container, which does not require a resin layer to be damaged even when coated with a correction coating film, and can be integrally formed with a canopy opening, and a container using the same. Aim.

[0007]

The resin-coated steel sheet for containers according to the first aspect of the present invention is formed by forming two layers of a lower metal chromium layer and an upper chromium hydrated oxide layer on the surface of the steel sheet. It is characterized in that an unoriented polyester resin layer is coated on a surface-treated steel sheet. The resin-coated steel sheet for containers according to claim 2, wherein the tin layer is formed so as to have an exposed portion on the surface of the steel sheet, and the lower metal chromium is formed so as to cover the tin layer and the exposed portion of the steel sheet surface. It is characterized in that a non-oriented polyester resin layer is coated on a surface-treated steel sheet in which three layers composed of a layer and an upper chromium hydrated oxide layer are formed. In these resin-coated steel sheets for containers, the unoriented polyester resin layer has an intrinsic viscosity (IV).
Of polyethylene terephthalate having a value of 0.4 to 1.4. Further, it is desirable that the unoriented polyester resin layer is a copolymerized polyester resin composed of polyethylene terephthalate and isophthalate having an intrinsic viscosity (IV) of 0.4 to 1.4. Further, it is desirable that the unoriented polyester resin layer be composed of two layers of an upper layer of polyethylene terephthalate and a lower layer of a copolymerized polyester resin composed of polyethylene terephthalate and isophthalate. Further, the unoriented polyester resin layer is composed of two layers of an upper layer of a copolymerized polyester resin composed of polyethylene terephthalate and isophthalate and a lower layer of a copolymerized polyester resin composed of polyethylene terephthalate and isophthalate having different isophthalate component amounts. Is desirable. Further, the unoriented polyester resin layer, the upper layer is polybutylene terephthalate,
It is desirable that the lower layer be composed of two layers of a copolymerized polyester resin composed of polyethylene terephthalate and isophthalate. The container of claim 8 is characterized by using the resin-coated steel sheet for a container according to any one of claims 1 to 7.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, as a resin-coated steel sheet for a container used in a large square can, a steel sheet which has excellent adhesion to a resin layer and has been subjected to a surface treatment capable of being welded is suppressed from heat embrittlement. By coating the unoriented polyester resin layer, the resin layer does not shrink during welding of the can body, a complete correction part is obtained, and the resin layer is damaged even if the hand ring is electrically welded to the canopy. Therefore, it was found that it was not necessary to cover with a coating film for correction. Furthermore, it was found that the canopy opening can be integrally formed without avoiding the resin layer or peeling off from the steel plate. Hereinafter, the present invention will be described.

First, a steel sheet applied to the present invention will be described. Since the resin-coated steel sheet applied to the present invention is premised on coating the resin layer, it is essential that the adhesiveness with the resin layer be good. Furthermore, the steel plate applied to the body of the large rectangular can, which is the object of the present invention, is preferably weldable because the seam is joined by electric welding. As a steel sheet having good adhesion to the resin layer, a surface-treated steel sheet (a so-called tin-free steel (TFS), which is formed by forming two layers of a lower metal chromium layer and an upper chromium hydrated oxide layer) TFS). Since the canopy and the canopy of the large rectangular can are wound around the body and used, it is preferable to use TFS having good adhesion to the resin layer.

Further, as described above, since the steel plate applied to the body portion is formed by joining the seam portion by electric welding, a steel plate which has been subjected to a surface treatment capable of electric welding and having good adhesion to the resin layer is used. There is a need. As a steel plate that has been subjected to surface treatment that can be electrically welded and has good adhesion to the resin layer,
A surface-treated steel sheet excellent in seam weldability and paint adhesion described in JP-B-2-16397 is exemplified. The surface-treated steel sheet described in Japanese Patent Publication No. 2-16397 discloses a tin layer formed so that an exposed portion is present on the surface of the steel sheet, and covering both the tin layer and the exposed portion of the steel sheet surface. A surface-treated steel sheet formed by forming a surface treatment layer consisting of three layers in which two layers consisting of a lower metal chromium layer and an upper chromium hydrated oxide layer are formed (a so-called compromise between tinplate and TFS, Hereinafter referred to as Arisu TFS). In the present invention, the above-mentioned tin-containing TFS is used as a base steel sheet for coating a resin layer of a can body. Naturally, this tinned TFS may be applied to a canopy and a ground cover.

Next, the unoriented polyester resin to be coated on the TFS or tinned TFS will be described. Examples of the unoriented polyester resin applicable to the present invention include polyethylene terephthalate having an intrinsic viscosity (IV) of 0.4 to 1.2, polyethylene terephthalate having an intrinsic viscosity of 0.4 to 1.2, and isobutylene. A phthalate copolymerized polyester resin, an upper layer of polyethylene terephthalate, a lower layer of a two-layered copolymerized polyester resin of polyethylene terephthalate and isophthalate, and an upper layer of polyethylene terephthalate and isophthalate having different amounts of isophthalate components. A polymerized polyester resin, a lower layer composed of two layers of a copolymerized polyester resin composed of polyethylene terephthalate and isophthalate, an upper layer composed of polybutylene terephthalate, and a lower layer composed of polyethylene terephthalate and isophthalate. It is preferably one of two layers of ester resin. If the intrinsic viscosity of the resin is less than 0.4 and more than 1.2, the melt viscosity of the resin pellets when heated and melted is too low or too high, and the resin pellets can be formed into a film or directly formed on a steel plate. When extruding and coating, work becomes extremely difficult.

The copolymerized polyester resin contains 70 to 95 mol% of terephthalic acid and 5 to 3 mol of isophthalic acid.
It is preferable to polymerize an acid component composed of 0 mol% and an alcohol component composed of 100 mol% of ethylene glycol. The copolymerized polyester resin has a low crystallization rate,
After coating the steel sheet with the surface treatment, it is processed as a canopy and the hand ring is electrically welded, or the resin layer is hardly damaged even when heated by welding.

It is preferable to use a single-layer or multiple-layer resin layer or the constituents of the resin layer depending on the intended use. A large-sized welding container (18-liter can) intended for the present invention may be subjected to painting printing showing the contents on the outer surface of the can. The coating printing is performed in a state of a flat plate before being formed into a can, and the flat plate coated with paint or ink is heated in an oven to dry and solidify the paint or ink. At this time, the flat plate may come into contact with a support called a wicket. However, if the resin layer covering the flat plate comes into contact with the wicket, the contact trace may remain and the appearance may be deteriorated. In particular, the resin layer is a single-layer resin layer made of a copolymerized polyester resin composed of polyethylene terephthalate and isophthalate, or a two-layer resin layer composed of an upper layer of a copolymerized polyester resin composed of polyethylene terephthalate and isophthalate having different amounts of isophthalate components. In the case where the amount of the isophthalate component is large, the polyethylene terephthalate and the isophthalate copolymer resin are likely to soften, and a contact mark with the wicket may remain. When used, it is preferable to use a resin having a small amount of isophthalate component.

In the case of a resin-coated steel sheet used for a canopy, when a severe process such as integral molding is performed to provide a canopy opening as shown in FIG. May worsen. In particular, the copolymer resin of polyethylene terephthalate and isophthalate is significantly whitened by processing, and when applied to the use of integrally forming the canopy opening, the application of a single-layer copolymer of polyethylene terephthalate and isophthalate is not preferred.
Also, in the two-layer resin layer, the lower layer of the copolymer resin of polyethylene terephthalate and isophthalate is preferably a thin layer to the extent that no whitening is observed.

The thickness of these resin layers is 10 to 100 μm
It is preferred that If the thickness is less than 10 μm, it is difficult to make the thickness of the film uniform, and the resin layer is formed of TFS or tin-TFS
(Hereinafter, when both are described, they are called surface-treated steel sheets.)
Cannot be coated. Further, even when the extrusion lamination method is used, it is extremely difficult to coat with a uniform thickness.
On the other hand, if it exceeds 100 μm, the resin cost becomes unnecessarily high. In the case of a two-layer resin, as described above, as the lower layer of the copolymer resin of polyethylene terephthalate and isophthalate becomes thinner, whitening becomes more difficult to recognize, but the workability of the two-layer resin layer decreases, and the above-mentioned canopy opening is integrated. When severe processing for forming is performed, the resin layer may peel off. Therefore, the thickness of the lower layer of the polyethylene terephthalate and isophthalate copolymer resin layer in the two-layer resin layer is 2 to 2.
It is preferably 10 μm.

Next, a method of coating the above-mentioned surface treated steel sheet with the above resin layer will be described. As the coating method,
Heat and melt the pellets of the raw resin, thickness 10-100μ
A film lamination method in which a film formed into a film of about m is pressed against a surface-treated steel sheet heated above the melting point of the resin, the pellets of the raw resin are heated and melted, and extruded directly from the T-die onto the surface-treated steel sheet for lamination Any of the extrusion lamination methods described above can be applied. Furthermore, since the film stretched and oriented in the longitudinal and transverse biaxial directions as described above shrinks due to heating by welding, in the present invention, the resin film formed on the film is in an unoriented state without stretching. It is essential to use it. In addition, in applications where highly corrosive contents are to be filled, a film pre-coated with a primer made of a resin such as polyester, acrylic, urethane, epoxy, or melamine is applied to the surface of the film that comes into contact with the surface-treated steel sheet. They may be stacked.

The resin layer may be coated on only one surface, which is the inner surface of the surface-treated steel plate can, or may be coated on both surfaces.
When a surface-treated steel sheet coated with a resin layer on both sides is applied to the canopy, it is necessary to remove the resin layer at the portion where the washer for attaching the ring is welded.

The resin-coated surface-treated steel sheet produced as described above is formed into a large square can as follows. First, the processing of the body member will be described. The above-mentioned tinned TFS was used as a base steel sheet, and a body member obtained by laminating a polyester resin layer except for facing edges was rolled, and the edges were subjected to electric resistance seam welding to form a cylindrical body. Then, a correction paint is applied to the welded portion to form a baking correction coating film layer. Thereafter, both ends of the opening are framed to provide a framed portion for tightening. Or, after processing the body member laminated with the polyester resin layer leaving the edge portion in the shape of a square can body, providing a framed processing portion for both sides of the opening and performing a framed process for winding and tightening, Next, the edge portion is subjected to electric resistance seam welding, and a correction paint is applied to the welded portion to form a baking correction coating film layer.

Next, the processing of the canopy and the canopy will be described. A polyester resin layer is laminated on the inner surface of the can using the above TFS or tinned TFS as a base steel plate, and a sealant is lined on a peripheral seam portion. In the case of a canopy, a hand ring washer is further electrically welded to the surface that will be the outer surface of the can. Furthermore, the canopy is pierced, the opening end of the perforated portion is protruded upward, and a ring-shaped base having an inner diameter of the perforation and an outer diameter slightly smaller than the diameter of the lid is crimped on the protruding portion of the canopy. An opening is provided. Alternatively, as shown in FIG. 1, the canopy is perforated, the opening end of the perforated portion is protruded upward, and further protruded outside the perforated portion, and the opening is directly formed integrally from the canopy plate. When TFS is used as the base steel sheet, it may be preferable to weld after removing the chromium metal layer and the chromium hydrated oxide layer.

Using a known method, a can body provided with a framed portion for winding up at both open ends as described above and a canopy and a canopy having a peripheral seam portion lined with a sealant are used. Double-wrapped to obtain the container of the present invention. The resin-coated steel sheet for a container of the present invention is not only applicable to a welding can produced by seam welding a can body as described above, but also to an adhesive can produced by bonding a can body. It is equally applicable.

[0021]

The present invention will be described in more detail with reference to the following examples. (Example) A cold-rolled steel sheet having a thickness of 0.32 mm was subjected to electrolytic cleaning and pickling by a conventional method, and then subjected to a surface treatment under the conditions shown in Tables 1 and 2 to obtain a coating having a coating amount shown in Table 3. Tin TFS and TFS were made. In Table 4, PET represents polyethylene terephthalate, PET / I represents a copolymerized polyester resin of polyethylene terephthalate and isophthalate, and PBT represents polybutylene terephthalate.

[0022]

[Table 1]

[0023]

[Table 2]

[0024]

[Table 3]

Next, a resin film shown in Table 4 was formed.
The above-mentioned tinned TFS and TFS using the known heat fusion method
Was laminated on one side. A commercially available biaxially stretched polyethylene terephthalate / isophthalate film was similarly laminated on one side of the tin-containing TFS. Thus, resin-coated steel sheets used in the present invention samples and comparative examples shown in Table 4 were prepared. For resin-coated steel sheets for canopies,
A ring for washer attachment was spot-welded to the surface not coated with resin by electric welding. Then, the opening shown in FIG. 1 was formed by integral molding.

[0026]

[Table 4]

(Evaluation of Characteristics) The heat shrinkage and heat resistance of the resin layer of the resin-coated steel sheet obtained as described above, the heat resistance of the resin layer on the back surface of the welded portion of the washer for attaching the ring, and the opening. Was evaluated under the following conditions. [Heat Shrinkage Resistance] A resin-coated steel sheet shown in Table 4 was 10 cm × 10
cm, and heated in an oven at 205 ° C. for 10 minutes, after which the resin layer contracted from the cut end: S (m
m) was measured, and the heat shrink resistance was evaluated according to the following five grades. Rating 5: 0 ≦ S ≦ 0.5 mm Rating 4: 0.5 mm <S ≦ 1 mm Rating 3: 1 mm <S ≦ 2 mm Rating 2: 2 mm <S ≦ 3 mm Rating 1: S> 3 mm

[Heat resistant workability] The resin-coated steel sheet shown in Table 4
After cutting into a size of 0 cm × 10 cm and heating in an oven at 205 ° C. for 10 minutes, a cross-hatched flaw having a vertical and horizontal crossing reaching the steel plate surface was made on the resin-coated surface of the resin-coated steel plate using a cutter knife. After that, an Erichsen overhanging process with a height of 5 mm was carried out centering on the intersection of the cross hatches, and peeling of the resin layer from the cross hatch and cracking of the resin layer were visually observed. Was evaluated. Rating 5: Peeling and cracking of the resin layer were not recognized. Rating 4: No peeling of the resin layer was observed, but slight cracking was observed which was not a problem in practical use. Rating 3: Peeling and cracking of the resin layer to such an extent as to cause a practical problem are observed. Rating 2: considerable peeling and cracking of the resin layer are observed. Rating 1: Peeling of the resin layer is observed in the entire processed portion.

[Heat resistance] A sponge impregnated with 3% saline was brought into contact with the back surface of the welded portion of the resin-coated steel plate to which the washer for attaching the ring for the canopy shown in Table 4 was welded, and the exposed portion of the steel plate of the resin-coated steel plate was contacted. A DC voltage of 6.5 V was applied between the sponge and the sponge, and the presence or absence of a current flowing through the resin layer was measured.

[Whitening resistance] After forming an opening shown in FIG. 1 by integral molding on a resin-coated steel sheet for a canopy shown in Table 4, the degree of whitening of the coating resin layer of the processed part was visually observed.
The degree of whitening resistance was evaluated according to the following five grades. Rating 5: No whitening was observed in the resin layer. Rating 4: Slight whitening was observed in the resin layer to such an extent that no practical problem occurred. Rating 3: Whitening is observed in the resin layer to such an extent as to cause a practical problem locally. Rating 2: Whitening is observed in a considerable part of the resin layer. Rating 1: Whitening of the resin layer is observed in the entire processed portion. Table 5 shows the results of the above characteristic evaluation.

[0031]

[Table 5]

As shown in Table 5, the resin-coated steel sheet for a welding container of the present invention has a resin layer having excellent heat shrinkage resistance, heat processing resistance, and heat resistance.

The resin-coated steel sheet of sample No. 20 in Table 4 was seam-welded as a material for the body part to prepare a can body, and a correction coating film was formed on the seam part on the inner side of the can using a polyester-based powder paint. After that, both ends of the opening were framed. The body was double-wrapped with the resin-coated steel sheet of Sample No. 21 as a canopy material and the resin-coated steel sheet of Sample No. 26 as a canopy material to form an 18-liter can. For 6 months, no leakage of soy sauce was observed.

[0034]

Industrial Applicability The present invention provides a large square can which is obtained by coating a non-oriented polyester resin layer which suppresses thermal embrittlement on a steel sheet which has excellent adhesion to a resin layer and has been subjected to a surface treatment capable of being welded. A resin-coated steel sheet for containers used for containers, the resin layer does not shrink when welding the can body, a complete correction part is obtained, and the resin layer is not damaged even if the hand ring is electrically welded to the canopy, There is no need to cover with a correction coating film.

[Brief description of the drawings]

FIG. 1 is a sectional view of a canopy opening formed by integral molding.

[Explanation of symbols]

 1 ... Resin coated steel sheet for container

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C25D 5/26 C25D 5/26 B 7/00 7/00 W (72) Inventor Yoshihide Kawamura Kudamatsu-shi, Yamaguchi Prefecture 1296 Toyoi 1 Toyo Kohan Co., Ltd. Technical Research Institute (72) Inventor Kenichi Miyata 1302 Higashi Toyoi, Kudamatsu City, Yamaguchi Prefecture Toyo Kohan Co., Ltd. Kudamatsu Plant F-term (reference) AK42D AK42J AL01D BA04 BA05 BA07 BA10A BA10D BA44 DA01 EH71 EJ64B EJ64C EJ68 EJ69 GB16 JA03 JA06D JK06 JL01 JL05 4K024 AA02 AA07 AB02 AB09 AB15 AB19 BA03 BB24 BC01 DB04 DB06 DB10 GA08 AA12 GA12 A08 GA12 CA33 EB01 EB08 EB11 4K044 AA02 AB02 BA02 BA10 BA15 BA21 BB04 BB05 BC04 BC05 BC08 BC11 CA16 CA18 CA31 CA62

Claims (8)

[Claims] 1. A container in which an unoriented polyester resin layer is coated on a surface-treated steel sheet having a steel sheet surface formed with two layers of a lower metal chromium layer and an upper chromium hydrated oxide layer. For resin coated steel sheet. 2. A tin layer formed so that an exposed portion is present on the surface of a steel sheet, a lower metal chromium layer formed so as to cover the tin layer and the exposed portion of the steel sheet surface, and an upper chromium water. A resin-coated steel sheet for a container, wherein a non-oriented polyester resin layer is coated on a surface-treated steel sheet obtained by forming three layers consisting of a hydrated oxide layer. 3. The container according to claim 1, wherein the unoriented polyester resin layer is polyethylene terephthalate having an intrinsic viscosity (IV) of 0.4 to 1.4. For resin coated steel sheet. 4. The non-oriented polyester resin layer is a copolymerized polyester resin comprising polyethylene terephthalate and isophthalate having an intrinsic viscosity (IV) of 0.4 to 1.4. The resin-coated steel sheet for a container according to claim 1. 5. The non-oriented polyester resin layer according to claim 1, wherein the upper layer is composed of two layers of polyethylene terephthalate, and the lower layer is composed of a copolymer polyester resin composed of polyethylene terephthalate and isophthalate.
Or the resin-coated steel sheet for containers according to 2. 6. The non-oriented polyester resin layer is composed of an upper layer of a copolymerized polyester resin composed of polyethylene terephthalate and isophthalate having different isophthalate component amounts, and a lower layer of a copolymerized polyester resin composed of polyethylene terephthalate and isophthalate. The resin-coated steel sheet for a container according to claim 1, wherein the steel sheet comprises a layer. 7. The non-oriented polyester resin layer according to claim 1, wherein the upper layer comprises two layers of polybutylene terephthalate, and the lower layer comprises a copolymerized polyester resin comprising polyethylene terephthalate and isophthalate.
Or the resin-coated steel sheet for containers according to 2. 8. A container using the resin-coated steel sheet for a container according to any one of claims 1 to 7.