JP2011213364A - Metal can - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a metal can whose cooling and warming characteristics are superior by increasing the amount of heat transmission by the radiation and absorption of infrared rays without spoiling its design characteristic.SOLUTION: This metal can 1 includes a metal can body part 2, and a base coat layer 3 coating the outer face side of the body part 2. The base coat layer 3 contains 20-70 mass% titanium dioxide 3a and an inorganic compound 3b altogether with the rest comprising a resin material when the titanium dioxide 3a is 10-65 mass% and the inorganic compound 3b comprising at least one of silicon dioxide, barium sulfate, calcium carbonate and aluminum oxide is 5-60 mass%. The covering area ratio of the base coat layer 3 relative to the surface area of the can outer face side of the body part 2 is at least 70% and the thickness of the base coat layer 3 is at least 5 μm.

Description

  The present invention relates to a metal can used as a beverage or food container.

  When beverages or foods in metal cans are sold at stores or vending machines, they are often cooled or heated to a temperature suitable for each beverage or food. Moreover, after a consumer purchases, it may cool with a household refrigerator. When cooled or heated in this way, a metal can with high thermal conductivity is efficient, and can be cooled and heated to a predetermined temperature in a short time compared to a glass bottle or the like.

  A printed layer with a printed design is provided on the outer surface of a normal metal can for beverages, and a topcoat layer is provided for the purpose of providing gloss, preventing wrinkles, and improving surface lubricity. Formed on top. In addition, a base coat layer may be formed under the print layer in order to improve the adhesion of the print layer and the sharpness of the design. In general, a white pigment such as titanium dioxide is added to the base coat layer for improving the sharpness of the design. For example, Patent Document 1 describes a metal can that enables various bright expressions by adding titanium dioxide to a print layer and a base coat layer. Titanium dioxide in the base coat layer is added for the above purpose, but as an incidental effect, heat transfer by infrared rays (radiation and absorption of infrared rays) between the metal can and the surroundings is likely to occur. Yes, it has improved cooling and warming to some extent compared to untreated metal cans.

JP 2009-57081 A

  However, since the metal itself has a very low infrared emissivity and absorption rate, the addition of titanium dioxide as an incidental effect as in conventional metal cans ensures a sufficient amount of heat transfer by infrared emission and absorption. There is a problem that can not be.

  Therefore, the present invention was created to solve such problems, and the problem is that the amount of heat transfer by radiation and absorption of infrared rays is increased without impairing the design, and the cooling and heating properties are excellent. To provide a metal can.

  In order to solve the above-mentioned problems, a metal can according to the present invention is coated on a metal can body portion and a can outer surface side of the can body portion, titanium dioxide: 10 to 65 mass%, silicon dioxide, barium sulfate. An inorganic compound consisting of at least one selected from calcium carbonate and aluminum oxide: 5 to 60% by mass, and a total of 20 to 70% by mass of the titanium dioxide and the inorganic compound, with the remainder being a base coat layer made of a resin material. And the covering area ratio of the base coat layer with respect to the surface area on the outer surface side of the can body is 70% or more, and the thickness of the base coat layer is 5 μm or more.

  According to the above configuration, the base coat layer includes a predetermined range of titanium dioxide and an inorganic compound, and the base coat layer has a predetermined coverage area ratio and a predetermined thickness. In addition to titanium dioxide having a high absorptance, the wavelength region of infrared rays to be emitted and absorbed contains an inorganic compound different from titanium dioxide, so that the wavelength region of infrared rays to be emitted and absorbed by the base coat layer is expanded. This increases the amount of heat transfer between the metal can and the surroundings due to infrared radiation and absorption. In addition, the design of the metal can is not impaired.

The metal can according to the present invention is characterized in that the titanium dioxide has a rutile crystal structure.
According to the above configuration, since the titanium dioxide has a rutile-type crystal structure, the infrared radiation emissivity and absorption rate of the titanium dioxide is increased. Therefore, the amount of heat transfer between the metal can and the surroundings due to infrared radiation and absorption. Increases further.

  The metal can according to the present invention further includes a printed layer made of an ink base material on which a design is printed on the base coat layer, and the thickness of the printed layer is 3 μm or less.

  According to the said structure, design property improves, without further providing the printing layer of predetermined thickness on a basecoat layer, without reducing the heat transfer amount of a metal can.

  The metal can according to the present invention further includes a top coat layer made of a resin material on the base coat layer, wherein the thickness of the top coat layer is 5 μm or less.

  According to the above configuration, by further providing a top coat layer having a predetermined thickness on the base coat layer, the gloss, scratch resistance and lubricity of the metal can can be improved without reducing the heat transfer amount of the metal can. To do.

  The metal can according to the present invention further comprises a printed layer made of an ink base material having a design printed on the base coat layer, and a top coat layer made of a resin material on the printed layer, and the printed layer and the The total thickness with the top coat layer is 5 μm or less.

  According to the above configuration, the print layer and the top coat layer are further provided in this order on the base coat layer, and the total thickness of the print layer and the top coat layer is a predetermined thickness. This improves the gloss, scratch resistance, lubricity and design of the metal can without lowering.

The metal can according to the present invention is characterized in that the can body is made of aluminum or an aluminum alloy.
According to the said structure, when a can main-body part consists of aluminum or aluminum alloy, the heat conductivity of a can main-body part becomes high, and the heat transfer amount of a metal can increases. In addition, the can body is lightened.

  According to the metal can according to the present invention, by providing a base coat layer containing titanium dioxide and an inorganic compound, the amount of heat transfer between the metal can and the surroundings can be increased without impairing the design, and cooling or heating can be achieved. Excellent in properties. In addition, according to the metal can according to the present invention, it is possible to provide gloss, wrinkle resistance, lubricity, and design by providing a print layer, a top coat layer, or a top coat layer formed on the print layer. Will also be excellent. According to the metal can according to the present invention, by using the aluminum or aluminum alloy can main body, the cooling property or the heating property is further improved, and the weight reduction of the metal can can be achieved.

The structure of DI can which is one of the metal cans which concern on this invention is shown typically, (a) is a perspective view, (b) is sectional drawing of a can copper part. It is a perspective view showing typically the composition of the bottle can which is one of the metal cans concerning the present invention. (A) is a schematic diagram which shows the manufacturing method of a DI can-shaped metal can, (b) is a schematic diagram which shows the manufacturing method of a bottle can-shaped metal can.

The metal can according to the present invention will be described with reference to the drawings.
As shown in FIG. 1 (a), a metal can 1 is used as a beverage or food container, and is connected to a bottomed cylindrical can body 12 and a can body 12, and this can body 12 It is a DI can shape including a neck portion 13 having a smaller outer diameter, and a flange portion 14 and an opening portion 15 formed at an end portion of the neck portion 13. The shape of the metal can 1 is not limited to a straight can shape, and as shown in FIG. 2, the outer diameter of the neck portion 23 is a bottle can shape that is further narrowed with respect to the outer diameter of the can body portion 22. Also good. A screw portion for screwing a screw cap (not shown) for sealing the contents (beverage etc.) filled in the metal can 1A into the end portion (opening 24) of the neck portion 23 of the metal can 1A. 25 is provided. In addition, in the metal can 1 of Fig.1 (a), a cover part (not shown) is wound around the flange part 14 instead of a screw cap. Moreover, the cross-sectional shape orthogonal to the axial direction of the can body parts 12 and 22 of the metal cans 1 and 1A is not limited to a circular shape (including an elliptical shape), and may be a polygonal shape.

  As shown in FIG. 1 (b), the metal can 1 includes a can body 2 and a base coat layer 3. Moreover, it is preferable that the metal can 1 further includes the printed layer 4, the top coat layer 5, or the top coat layer 5 formed on the printed layer 4. Each configuration will be described below.

(Can body part)
As shown in FIG. 3, the can main body 2 is a container obtained by processing the metal plate A into a DI can shape, a bottle can shape, or the like. The can body 2 is made of a metal material, made of a metal material such as steel, aluminum, or an aluminum alloy, preferably aluminum or an aluminum alloy, more preferably a JIS standard 3000 series alloy, and most preferably a 3004 alloy. When the can main body 2 is made of aluminum or an aluminum alloy, the cooling or heating property of the metal can 1 is improved. This is due to the high thermal conductivity of aluminum or aluminum alloys. Moreover, weight reduction can be achieved because the can main-body part 2 consists of aluminum or an aluminum alloy. The thickness of the can main body 2 is appropriately set in consideration of the strength and weight reduction of the metal can 1 and is, for example, 0.1 to 0.5 mm.

  The surface of the can main body 2 may be subjected to a chemical conversion treatment such as a zirconium phosphate treatment or other chemical conversion treatment containing zirconium, a phosphoric acid chromate treatment, or a chemical conversion treatment containing titanium as a coating base treatment. Thereby, adhesiveness and corrosion resistance with a coating film (basecoat layer 3) can be improved.

(Base coat layer)
The base coat layer 3 is a resin coating film that is coated on the outer surface side of the can main body 2 and is at least one selected from titanium dioxide 3a: 10 to 65% by mass, silicon dioxide, barium sulfate, calcium carbonate, and aluminum oxide. Inorganic compound 3b composed of 5 to 60% by mass, and the total of titanium dioxide 3a and inorganic compound 3b: 20 to 70% by mass, with the remainder being made of resin material 3c.

  The resin material 3c serving as a coating film substrate of the base coat layer 3 is particularly limited as long as the base coat layer 3 can be formed by coating and baking by dispersing titanium dioxide 3a and an inorganic compound 3b in the resin solution or dispersion. Although not used, acrylic resins, polyesters, epoxy resins, amino resins, copolymers thereof, and the like are used. The application may be performed by a conventionally known application method such as spray or roll coater. The baking condition is not particularly limited as long as the resin material 3c is sufficiently cured. For example, the baking is performed at a baking temperature of 170 to 230 ° C. for 10 to 60 seconds.

  By containing the titanium dioxide 3a, the base coat layer 3 increases the amount of heat transfer due to infrared radiation and absorption, and the cooling property or heating property of the metal can 1 is improved. This is due to the high infrared emissivity and absorptance of titanium dioxide 3a. In addition to the titanium dioxide 3a, the base coat layer 3 can contain an inorganic compound 3b, thereby expanding the wavelength region of infrared rays that the base coat layer 3 emits or absorbs. This is because the inorganic compound 3b emits or absorbs infrared rays having a wavelength region different from that of the titanium dioxide 3a. As a result, the amount of heat transfer due to infrared radiation and absorption is further increased without impairing the design, and the cooling or heating property of the metal can 1 is further improved.

  Therefore, when the content of titanium dioxide 3a is less than 10% by mass, the content of inorganic compound 3b is less than 5% by mass, or the total content of titanium dioxide 3a and inorganic compound 3b is less than 20% by mass, sufficient heat transfer is obtained. I can't get it. Further, when the content of titanium dioxide 3a exceeds 65% by mass, the content of inorganic compound 3b exceeds 60% by mass, or the total content of titanium dioxide 3a and inorganic compound 3b exceeds 70% by mass, the coating film The adhesiveness of is reduced.

  The titanium dioxide 3a has three types of crystal structures: tetragonal rutile type or anatase type and orthorhombic brookite type. Any crystal structure has a function of increasing the amount of heat transfer by infrared radiation and absorption. And since the emissivity and absorptance of infrared rays resulting from the crystal structure are highest in the rutile type, it is preferable to use rutile type titanium dioxide 3a.

  The particle diameters of the titanium dioxide 3a and the inorganic compound 3b are not particularly limited as long as they can be dispersed in a resin solution to form a paint, but in order to efficiently emit and absorb infrared rays, the particle diameters measured with an optical microscope or the like are used. Is preferably 3.0 μm or less. Also, graphite and the like have the effect of increasing the amount of heat transfer by infrared radiation and absorption, but graphite and the like cannot be used because the design restrictions are increased.

  The base coat layer 3 has a covering area ratio of 70% or more with respect to the surface area on the outer surface side of the can body 2. When the covering area ratio is less than 70%, an increase in the amount of heat transfer due to infrared radiation and absorption cannot be expected, and the cooling property or heating property of the metal can 1 decreases.

  The base coat layer 3 has a thickness of 5 μm or more. If the thickness is less than 5 μm, an increase in heat transfer due to infrared radiation and absorption cannot be expected. Further, the thickness can be expected to increase the amount of heat transfer as the thickness increases, but does not change much when the thickness exceeds a certain level. Furthermore, if it is too thick, heat conduction may be hindered, and the cost will increase. Therefore, the thickness is preferably 5 to 30 μm. The thickness is controlled by the coating amount of the paint in which titanium dioxide 3a and inorganic compound 3b are dispersed in a resin solution or dispersion.

(Print layer)
The print layer 4 is a layer formed on the base coat layer 3 and made of an ink base material on which a design is printed, and has a thickness of 3 μm or less. By providing such a printing layer 4, the design can be improved without reducing the heat transfer amount of the metal can 1. The ink base material is not particularly limited as long as it can print the design, and examples thereof include solvent-based inks containing alkyd resin as a main component and containing known pigments and additives.

  When the thickness of the printing layer 4 exceeds 3 μm, the heat transfer amount of the metal can 1 is lowered, and the cooling property or heating property of the metal can 1 may be lowered. Moreover, the formation of the printing layer 4 is performed by applying and baking ink on the can main body 2, and the thickness of the printing layer 4 is controlled by the amount of ink applied. The coating method may be performed by a conventionally known printing method. The baking condition is not particularly limited as long as the ink is sufficiently cured. For example, the baking is performed at a baking temperature of 170 to 230 ° C. for 10 to 30 seconds.

(Topcoat layer)
The top coat layer 5 is formed on the base coat layer 3 and is a layer made of a resin material, and the thickness thereof is 5 μm or less. By providing such a topcoat layer 5, the gloss, scratch resistance and lubricity can be improved without reducing the heat transfer amount of the metal can 1. The resin material is not particularly limited as long as a coating film can be formed on the base coat layer 3, and an epoxy resin, a phenol resin, a polyester, an amino resin, an acrylic resin, a copolymer thereof, or the like is used. Moreover, you may mix | blend additives, such as a wax.

  When the thickness of the topcoat layer 5 exceeds 5 μm, the heat transfer amount of the metal can 1 is lowered, and the cooling property or heating property of the metal can 1 may be lowered. The top coat layer 5 is formed by applying and baking a resin solution or dispersion to the can body 2, and the thickness of the top coat layer 5 is controlled by the amount of the resin solution or dispersion applied. To do. The application method may be a conventionally known application method such as spraying or roll coater. The baking conditions are not particularly limited as long as the topcoat layer is sufficiently cured. For example, the baking is performed at a baking temperature of 170 to 230 ° C. for 10 to 30 seconds.

  The top coat layer 5 may be formed on the printing layer 4 formed on the base coat layer 3. In this case, the total thickness of the printing layer 4 and the topcoat layer 5 is 5 μm or less. If the total thickness exceeds 5 μm, the heat transfer amount of the metal can 1 is reduced, and the cooling property or heating property of the metal can 1 may be reduced. In addition, when forming the topcoat layer 5 on the printing layer 4, after apply | coating the ink for forming the printing layer 4, the resin solution for forming the topcoat layer 5 without baking Alternatively, a dispersion liquid may be applied. Then, for example, the printing layer 4 and the topcoat layer 5 can be formed simultaneously by baking at a baking temperature of 170 to 230 ° C. for 10 to 30 seconds.

  In addition, although the metal can 1 which concerns on this invention is not shown in figure, it is desirable to form a resin coating film (inner surface coating layer) also in the can inner surface side of the can main-body part 2. FIG. Thereby, the corrosion resistance with respect to the contents can be improved. The resin used for the inner surface coating layer can be appropriately selected depending on the type of contents, etc., but epoxy resins, phenol resins, polyesters, amino resins, acrylic resins, polyvinyl chloride, copolymers thereof, etc. may be used. it can. The thickness of the inner surface coating layer can also be appropriately selected depending on the type of contents, etc., but if it is too thick, the cost is increased and heat conduction may be hindered. The inner surface coat layer is formed by applying and baking a resin solution or dispersion on the inner surface side of the can body 2, and the thickness of the inner surface coat layer is controlled by the amount of the resin solution or dispersion applied. . The coating method may be performed by a conventionally known coating method such as spraying. The baking condition is not particularly limited as long as the inner surface coating layer is sufficiently cured. For example, the baking is performed at a baking temperature of 170 to 230 ° C. for 30 to 90 seconds.

Next, the manufacturing method of a metal can is demonstrated with reference to drawings.
When the metal can is in the shape of a DI can, for example, as shown in FIG. 3A, the bottom of the cylindrical can body portion is formed by subjecting the metal plate A to can body molding such as cup molding or DI molding. 12 is formed. Thereafter, if necessary, a coating treatment such as cleaning and zirconium phosphate is performed. Subsequently, the base coat layer 3 and, if necessary, the printed layer 4, the top coat layer 5, or both layers (see FIG. 1B) are formed on the outer surface side of the can body 12 by coating and baking. Furthermore, if necessary, an inner surface coating layer is formed on the inner surface side of the can body portion 12 by coating and baking. And the DI can-shaped metal can 1 can be manufactured by performing the necking process for forming the neck part 13 in the bottomed cylindrical can body part 12, and the flange process for forming a flange part. .

  Further, when the metal can has a bottle can shape (here, a two-piece bottle can shape will be described as an example), for example, as shown in FIG. A bottomed cylindrical can body 22 is formed by forming a can body such as forming. Thereafter, if necessary, a coating treatment such as cleaning and zirconium phosphate is performed. Subsequently, the base coat layer 3 and, if necessary, the print layer 4, the top coat layer 5, or both layers (see FIG. 1B) are formed on the outer surface side of the can body 22 by coating and baking. Furthermore, if necessary, an inner surface coating layer is formed on the inner surface side of the can body 22 by coating and baking. The bottomed cylindrical can body portion 22 is subjected to necking processing for forming the neck portion 23, threading processing for forming the screw portion 25, and curling of the end portion 24 to form a bottle can shape. Metal can 1A can be manufactured.

Next, examples of the present invention will be described.
A can body portion made of an aluminum alloy (3004 alloy) having a can body diameter of 66 mm and a capacity of 350 ml in a DI can shape (see FIG. 1A) was produced.
A base coating layer was formed by applying a resin paint mainly composed of an acrylic resin to the outer surface of the can body and baking it at 200 ° C. for 1 minute. In the resin paint, titanium dioxide (A) and inorganic compound (in advance) so that the contents of titanium dioxide (A) and inorganic compound (B) in the base coat layer after baking are the amounts shown in Table 1. B) was added. Further, the coverage area ratio and thickness of the base coat layer in the total surface area on the outer surface side of the can were as shown in Table 1.
Next, a resin paint mainly composed of polyester was applied on the base coat layer and baked at 200 ° C. for 30 seconds to form a top coat layer, thereby obtaining a metal can (sample). The thickness of the top coat layer was as shown in Table 1.

  About the produced metal can (sample), the cooling property and the adhesiveness of the base coat layer or the top coat layer were evaluated by the following methods. The results are shown in Table 1.

(Coolability evaluation method)
Cooling that measures 350 minutes of water in a metal can (sample) after cooling in a household refrigerator with an internal temperature of 5 ° C and a water temperature of 10 ° C. A test was conducted. A similar cooling test was also performed on a metal can without a base coat layer and a top coat layer. The time until the water temperature reaches 10 ° C. is shortened by 10 minutes or more than the metal can without the base coat layer and the top coat layer. When it was small, it was set as "x: Fail".

(Adhesion evaluation)
A tape peeling test was conducted to attach the tape to the outer surface of the metal can (sample) and then peel the tape. “○: Pass” indicates that the base coat layer or top coat layer did not adhere to the tape at all and had good adhesion, and “×: indicates that the base coat layer or top coat layer adhered to the tape and the adhesion was poor. “Fail”.

  From the results in Table 1, sample No. 1 satisfying the requirements of the present invention was obtained. As for 1-15 (Example), cooling property and adhesiveness passed.

  In contrast, sample no. In No. 16 (Comparative Example), the content of titanium dioxide exceeded the upper limit value, and no inorganic compound was contained. Sample No. In No. 17 (Comparative Example), since the content of the inorganic compound was less than the lower limit, the cooling performance was unacceptable. Sample No. No. 18 (Comparative Example) did not contain titanium dioxide, and the content of the inorganic compound exceeded the upper limit value.

  Sample No. In 19 (Comparative Example), the content of titanium dioxide was less than the lower limit value, so the cooling performance was unacceptable. Sample No. In No. 20 (Comparative Example), the total content of titanium dioxide and the inorganic compound was less than the lower limit value, so the cooling performance was unacceptable. Sample No. In No. 21 (Comparative Example), the coverage ratio of the base coat layer was less than the lower limit value, so the cooling performance was unacceptable.

  Sample No. In No. 22 (Comparative Example), since the thickness of the base coat layer was less than the lower limit, the cooling performance was unacceptable. Sample No. In No. 23 (Comparative Example), the content of titanium dioxide exceeded the upper limit, and the total content of titanium dioxide and the inorganic compound also exceeded the upper limit. Sample No. In No. 24 (Comparative Example), the content of the inorganic compound exceeded the upper limit value, and the total content of titanium dioxide and the inorganic compound also exceeded the upper limit value. Sample No. Since No. 25 (Comparative Example) did not contain titanium dioxide and an inorganic compound, the cooling performance was unacceptable. Sample No. Since No. 26 (Comparative Example) did not contain an inorganic compound, the cooling performance was unacceptable.

DESCRIPTION OF SYMBOLS 1 Metal can 2 Can main-body part 3 Basecoat layer 3a Titanium dioxide 3b Inorganic compound 3c Resin material 4 Printing layer 5 Topcoat layer

Claims (6)

A metal can body,
The can body is coated on the outer surface side of the can, titanium dioxide: 10 to 65% by mass, at least one inorganic compound selected from silicon dioxide, barium sulfate, calcium carbonate, and aluminum oxide: 5 to 60% by mass, the carbon dioxide A total of titanium and the inorganic compound: 20 to 70% by mass, and a base coat layer comprising the resin material as the balance,
The coverage area ratio of the base coat layer with respect to the surface area on the outer surface side of the can body portion is 70% or more,
A metal can, wherein the base coat layer has a thickness of 5 μm or more.   The metal can according to claim 1, wherein the titanium dioxide has a rutile-type crystal structure. On the base coat layer, further comprising a printing layer made of an ink base material printed with a design,
The thickness of the said printing layer is 3 micrometers or less, The metal can of Claim 1 or Claim 2 characterized by the above-mentioned. A top coat layer made of a resin material is further provided on the base coat layer,
The thickness of the said topcoat layer is 5 micrometers or less, The metal can of Claim 1 or Claim 2 characterized by the above-mentioned. A printing layer made of an ink base material having a design printed on the base coat layer; and a top coat layer made of a resin material on the printing layer;
The total thickness of the said printing layer and the said topcoat layer is 5 micrometers or less, The metal can of Claim 1 or Claim 2 characterized by the above-mentioned.   The metal can according to any one of claims 1 to 5, wherein the can body is made of aluminum or an aluminum alloy.

Images