Can for sparkling beverages and method for manufacturing same

Abstract

To provide a can for sparkling drinks, which can further improve the sparkling properties, and a method for manufacturing the same. The can for a sparkling beverage has an upper surface, a lower surface, and a body portion, and the inner surface of the body portion is provided with a plurality of first recesses each having a diameter of 5 μm or more, and the number of the plurality of first recesses is 1 mm. 2 There are 200 to 2000 pieces per

Description

Technical Field

[0001] The present invention relates to a can for a foaming beverage and a method for manufacturing the same.

Background Art

[0002] Foaming beverages such as beer may be provided in a sealed container. One of the important characteristics of a foaming beverage is its foaming property. Various studies have been conducted to obtain an appropriate amount of foam when drinking.

[0003] In order to enhance the foaming property, there are also known ones in which the structure of the container is devised. For example, Patent Document 1 (Japanese Patent No. 4758693) discloses a technique aimed at providing a can for a foaming beverage that has no adverse effect on the filling property and can improve the foaming property at the time of opening the can. In Patent Document 1, in a can for a foaming beverage, an organic resin coating layer is provided on the inner surface of the can, an organic resin coating material in which predetermined large-diameter particles are mixed in a predetermined amount occupies 20% or more and 60% or less of the inner surface area of the can, an organic resin coating material in which predetermined small-diameter particles are mixed in a predetermined amount occupies the remaining part of the inner surface area of the can, and at least a part of the large-diameter particles is formed in the organic resin coating layer as a concave portion generated by detachment or a convex portion generated by remaining, and a concave portion generated by the detachment of the small-diameter particles.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The present inventors consider that they want to further improve the foaming property. Therefore, an object of the present invention is to provide a can for a foaming beverage and a method for manufacturing the same that can further improve the foaming property.

Means for Solving the Problems

[0006] The inventors of the present invention have discovered that the above problems can be solved by forming a predetermined structure on the inner surface of the can, and have arrived at the present invention. That is, the present invention is realized by the following means. [1] Having an upper surface, a lower surface, and a body, the inner surface of the body is provided with a plurality of first recesses having a diameter of 5 μm or more and 20 μm or less, and the number of the plurality of first recesses is 1 mm 2 Each pack contains 200 to 2000 cans of carbonated beverages. [2] Multiple second recesses having a diameter of 0.5 μm or more and less than 5 μm are provided on the inner surface of the body, and the number of the multiple second recesses is 1 mm 2 The carbonated beverage cans described in [1] are 5,000 to 20,000 per can. [3] The can for effervescent beverages according to [1] or [2], wherein a resin layer is provided on the inner surface of the body, and the first recess is formed in the resin layer. [4] The can for effervescent beverages according to any one of [1] to [3], wherein the top surface is formed by a can lid configured to open in a full-open manner. [5] A method for manufacturing a foamed beverage can having an upper surface, a lower surface, and a body, comprising the steps of: painting a paint containing resin and wax on the inner surface of the body, or an area that is to become the inner surface of the body; and heating the painted paint to form a resin layer and remove the wax, wherein the average particle size of the wax in the paint is 1 μm or more, and the wax content in the paint is 7 to 40 parts by mass per 100 parts by mass of nonvolatile components (excluding wax). [6] The manufacturing method according to [5], wherein the wax comprises polyethylene wax. [7] The manufacturing method according to [5] or [6], wherein the paint comprises at least one resin selected from the group consisting of epoxy resin, acrylic resin, polyester resin, and urethane resin. A carbonated beverage comprising a beverage can as described in any of [8][1] to [4], and a carbonated drinkable liquid filled in the beverage can. [Effects of the Invention]

[0007] According to the present invention, a can for effervescent beverages and a method for manufacturing the same are provided, which can further improve the effervescence. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a schematic cross-sectional view showing the crater-like structure. [Figure 2] Figure 2 is a schematic cross-sectional view illustrating the method of forming crater-like structures. [Figure 3A] Figure 3A is a micrograph showing the inner surface of the body of the control group. [Figure 3B] Figure 3B is a micrograph showing the inner surface of the body of test section 1. [Figure 3C] Figure 3C is a micrograph showing the inner surface of the body of test section 2. [Figure 4A] Figure 4A shows a 3D image of the inner surface of the torso of the control group. [Figure 4B] Figure 4B shows a 3D image of the inner surface of the torso in test section 1. [Figure 4C] Figure 4C shows a 3D image of the inner surface of the torso in test section 2. [Figure 5A] Figure 5A shows the measurement locations for the surface profile of test section 2. [Figure 5B] Figure 5B is a graph showing the measurement results of the surface profile in test section 2. [Modes for carrying out the invention]

[0009] Embodiments of the present invention will be described in detail below. The effervescent beverage can according to this embodiment has a top surface, a body, and a bottom surface. The body and bottom surface are integrated or joined together, forming a bottomed cylindrical shape, and the opening at the top is closed by the top surface in a way that allows it to be opened.

[0010] Multiple first recesses are provided on the inner surface of the body. In addition, in this specification, the "recess" refers to a structure with a depth of 1 μm or more. When viewed from the front, the first recess is generally circular. The first recess is a recess with a diameter of 5 μm or more and 20 μm or less. The number of the first recesses is 200 to 2000 per 1 mm 2 and preferably 300 to 1500, more preferably 400 to 1200. The average depth of the plurality of first recesses is, for example, 1 to 5 μm, and preferably 2 to 4 μm. In addition, the number and average depth of the first recesses can be determined using, for example, a laser microscope.

[0011] The first recess is preferably a crater-shaped structure. FIG. 1 is a cross-sectional view schematically showing the crater-shaped structure. As shown in FIG. 1, the crater-shaped structure refers to a structure in which the edge portion of the recess is raised conversely. [[ID=十五]]

[0012] Preferably, in this embodiment, a plurality of second recesses are further provided on the inner surface of the body portion. The second recess is a recess with a diameter of 0.5 μm or more and less than 5 μm. The number of the plurality of second recesses is 5000 to 20000 per 1 mm 2 and preferably 7000 to 15000. The average depth of the plurality of second recesses is, for example, 1 to 5 μm, and preferably 2 to 4 μm. The number and average depth of the second recesses can be determined by the same method as the first recesses. Similar to the first recess, the second recess is preferably a crater-shaped structure.

[0013] Preferably, the can for a foaming beverage according to this embodiment is made of metal. Further preferably, a resin layer obtained by coating and drying a paint on a metal layer is provided on the inner surface of the body portion, and the first recess and the second recess are formed in the resin layer. The thickness of the resin layer is, for example, 1 to 10 μm, and preferably 3 to 8 μm. It should be noted that in this invention, the term "resin layer" refers to the layer after the applied paint has dried, and is distinct from the paint layer before drying.

[0014] Preferably, the can lid of the effervescent beverage can according to this embodiment is a fully open end. A fully open end is a type of lid in which 30% or more of the area of ​​the top surface of the can lid is open. Preferably, the open area is 50% or more of the top surface of the can lid, more preferably 90% or more, and even more preferably the entire top surface of the can lid. A preferred embodiment is a lid of the type in which a score (notch) is cut around the entire circumference of the top surface of a circular can lid, allowing the entire top surface of the lid to detach from the can body and open. On the other hand, the lid may not detach completely, with a portion of the lid remaining attached to the can body. A fully open end allows for a visual perception of the foam emanating from the can body compared to a regular can lid, which evokes the image of beer poured into a mug. In addition, because a larger volume of liquid flows into the mouth at the same angle than with a regular can lid, the foam and liquid can be enjoyed at the same time.

[0015] The capacity of a can for effervescent beverages (the amount of beverage liquid filled inside) is, for example, 135 to 1000 ml, preferably 320 to 500 ml. Furthermore, if the lid is circular, the diameter of the opening of the can for effervescent beverages is, for example, 200 to 211 mm in diameter, preferably 202 to 206 mm in diameter.

[0016] Next, we will describe an example of a manufacturing method for the carbonated beverage cans mentioned above. The manufacturing method according to this embodiment includes the steps of applying a paint containing resin and wax to the inner surface of the body (or the area that is to become the inner surface of the body), and subsequently heating the applied paint to form a resin layer on the inner surface and remove the wax (hereinafter also referred to as the baking step). According to this method, a recess is formed in the resin layer by removing the wax. While wax is generally used in the can manufacturing process to prevent damage to the coating, in this specification, wax refers to a component that is solid and particulate at room temperature. One method for forming a can body with a resin layer on the inside is to first form a bottomed cylindrical can body by drawing and ironing, then apply the paint according to the present invention by spray painting and bake it to form the resin layer (the resulting can is called a two-piece can). Alternatively, one can also be used to prepare a metal plate having a region that will become the inner surface, apply paint to the region that will become the inner surface and bake it to form a resin layer, then shape the metal plate with the resin layer into a cylindrical shape, and crimp the bottom of the can to obtain a bottomed cylindrical can body (the resulting can is called a three-piece can).

[0017] The painting and baking processes are described in detail below.

[0018] First, prepare a paint containing resin and wax. For example, water-based paints can be used as the coating. Examples of resins used in paints include epoxy resin, acrylic resin, polyester resin, and urethane resin.

[0019] The wax in the paint is defined as wax with an average particle size of 1 μm or larger. Here, the average particle size refers to the particle size (D50) at which the frequency cumulative volume is 50%, and this value was measured using a dynamic light scattering particle size distribution analyzer (Nikkiso Co., Ltd. "Microtrac S3500") on an aqueous dispersion containing approximately 20% by mass of wax, diluted 500 times with water. The average particle size of the wax is preferably 1 to 15 μm, more preferably 2 to 10 μm, and even more preferably 3 to 8 μm.

[0020] The wax content in the paint is, for example, 7 to 40 parts by mass, preferably 10 to 40 parts by mass, and more preferably 12 to 30 parts by mass, per 100 parts by mass of nonvolatile components (excluding wax) in the paint. The nonvolatile components (excluding wax) referred to here are the components that remain on the substrate after the paint is applied and baked, forming a resin layer, excluding wax.

[0021] Furthermore, multiple types of wax with different average particle sizes may be used in combination. By combining multiple waxes with different average particle sizes in this way, it becomes easier to control the size and number of recesses.

[0022] As for the wax, for example, one with a softening point of 90 to 160°C, preferably 110 to 140°C, is used. Carnauba wax and polyethylene wax can be used as the wax. The wax can be used in various forms, such as powder, paste, or water / solvent dispersion, but from the viewpoint of dispersion stability in the paint, it is preferable to use water or solvent dispersion.

[0023] In this embodiment, the painting method is preferably spray painting such as air spray, airless spray, or electrostatic spray, roll coater painting, dipping painting, or electrodeposition painting, with spray painting being more preferred. To ensure proper drying of the paint and the formation of a uniform resin layer, it is preferable to perform a baking process immediately after painting. The conditions for the baking process can be appropriately selected to allow the paint to dry and the resin layer to form, but 150-280°C for 10 seconds to 30 minutes is preferable. Furthermore, in order to melt the wax during this baking process and cause it to detach from the paint film, 180-280°C for 1 minute to 30 minutes is more preferable. The thickness of the resin layer after baking is, for example, 1-10 μm, preferably 3-8 μm. Figure 2 is a schematic cross-sectional view illustrating the method of forming a crater-like structure. As shown in Figure 2, by applying and drying the paint, water and solvents first evaporate, forming a resin layer 1. Here, the wax 2 is initially positioned so as to be embedded in the resin layer 1. The upper part of the wax 2 is exposed on the surface of the resin layer 1. Subsequently, during baking, the wax 2 melts and detaches from the resin layer 1. This forms crater-like depressions in the resin layer 1.

[0024] Subsequently, beverage cans are manufactured, filled with drinkable liquid, and sealed, in the same manner as is commonly used in this industry. The filling of the drinkable liquid is preferably carried out at a low temperature (e.g., 1-20°C).

[0025] According to the method described above, by using a paint containing a specific amount of wax having a specific average particle size, recesses of a specific size are formed on the inner surface of the can body at a specific density. By using a can for effervescent beverages in which such a special structure is formed on the can body at a specific density, extremely high foaming properties can be achieved.

[0026] Furthermore, the beverage liquid filled into the effervescent beverage can according to this embodiment may be any effervescent liquid and is not particularly limited. Preferably, the beverage to be filled is a beer-like sparkling beverage. A "beer-like sparkling beverage" means a sparkling beverage that has a flavor, taste, and texture equivalent to or similar to beer, regardless of alcohol content, whether or not malt and hops are used, or whether or not it is fermented, and has high thirst-quenching and drinkability (the property of being able to drink many glasses without getting tired of it). A beer-like sparkling beverage may be an alcoholic beverage, or it may be a so-called non-alcoholic beverage or low-alcohol beverage with an alcohol content of less than 1% by volume. It may also be a beverage made from malt, or a beverage not made from malt, or it may be a fermented beverage produced through a fermentation process, or it may be a non-fermented beverage produced without a fermentation process. Examples of beer-like sparkling beverages include beer, sparkling alcoholic beverages made from malt, sparkling alcoholic beverages that do not use malt, low-alcohol sparkling beverages, and non-alcoholic beer. In addition, liqueurs obtained by mixing a beverage made from malt and produced through a fermentation process with an alcohol-containing distillate may also be included. More preferably, the beverage to be filled is beer. When beer is filled into a can for effervescent beverages according to this embodiment, foam is generated from the inside of the can as soon as it is opened, and the foam and beer can be consumed together. However, even when beverages other than beer are filled into the bottles, the flavor of the contents can be strongly perceived because aromatic components evaporate as the bottles are carbonated. Preferably, the effervescent beverage has a gas pressure of 2 to 4 gas volumes. [Examples]

[0027] To further explain the present invention, the inventors will now describe some examples they have provided.

[0028] (Control group) An aluminum container (350 ml capacity) with a bottom and a body was prepared. A water-based epoxy acrylic paint was also prepared, containing 1 part by mass of carnauba wax with an average particle size of 0.3 μm per 100 parts by mass of the non-volatile components (excluding wax) in the paint. The prepared paint was spray-coated onto the entire inner surface of the body of the container, and then heated at 200°C for 2 minutes to obtain a beverage can for the control group. The average thickness of the resin layer on the body was 5 μm.

[0029] (Test Section 1) As the wax, a wax with an average particle size of 6 μm was used in an amount of 7.5 parts by mass per 100 parts by mass of the non-volatile components (excluding wax) in the paint. In other respects, the same procedure as in the control group was followed to obtain the beverage can according to Example 1.

[0030] (Examination Section 2) Two types of wax were used: a wax with an average particle size of 6 μm (first wax) and a wax with an average particle size of 4 μm (second wax). The amount of the first wax was 7.5 parts by mass per 100 parts by mass of non-volatile components (excluding wax) in the paint. The amount of the second wax was also 7.5 parts by mass per 100 parts by mass of non-volatile components (excluding wax) in the paint. In other respects, the beverage cans for test group 2 were obtained in the same manner as for the control group.

[0031] (Measurement of gas leakage) 350 ml of beer was gently poured into each prepared beverage can, and its mass was measured. After letting it stand for 5 minutes, the mass was measured again. The difference between the mass before and after the 5-minute standing period was calculated as the "amount of gas released." Five measurements were taken for each beverage can. The upper and lower limits of the gas release measurements for each beverage can are shown in Table 1 below. [Table 1]

[0032] As shown in Table 1, the amount of gas released was significantly greater in test sections 1 and 2 than in the control section. Furthermore, the amount of gas released in test section 2 was even greater than in test section 1. The amount of gas released represents the amount of gas released (the size of the bubbles), meaning that a larger value indicates higher effervescence (larger bubbles).

[0033] (Evaluation of coverage) Each prepared beverage can was filled with beer, and the top was closed with a fully opening can lid. After filling, the beverage cans were left to stand at 4°C for 24 hours. Next, the cover time (the time from opening the beverage can until foam rises from inside and the top of the beverage can is covered by the foam) was set at 10 seconds, and the cover performance was evaluated. Ten tests were conducted for each beverage can, and the number of cans with a cover time of 10 seconds or less was counted. The results are shown in Table 2. [Table 2]

[0034] As shown in Table 2, the coverage was greatest in Test Group 2, followed by Test Group 1, and then the control group. The results of the coverage evaluation also showed that Test Groups 1 and 2 were superior to the control group, with Test Group 2 being particularly superior.

[0035] (Measurement of surface condition) The surface condition of the inner surface of each beverage can was observed. Specifically, images of the inner surface of the can were acquired using a white light interferometer-equipped laser microscope VK-X3000 (manufactured by Keyence Corporation). Figures 3A to 3C show the images obtained for the control group, test group 1, and test group 2, respectively. Figures 4A to 4C show 3D processed images obtained for the control group, test group 1, and test group 2, respectively.

[0036] Furthermore, the surface profile was measured for test section 2. Figure 5A shows the measurement locations of the surface profile. That is, the surface profile was measured along the line segment shown in Figure 5A. Figure 5B is a graph showing the measurement results of the surface profile. In Figure 5B, the horizontal axis represents the position, and the vertical axis represents the height (depth) from the baseline.

[0037] Furthermore, based on the obtained images, the number of recesses with a diameter of 5 μm or more (first recesses) and recesses with a diameter of 1 μm or more and less than 5 μm (second recesses) was counted using a white light interferometer-equipped laser microscope VK-X3000 (manufactured by Keyence Corporation), and the number of recesses was measured per 1 mm. 2 The number of winning items was calculated. In counting the number of recesses, we counted the number of recesses with a depth of 1 μm or more from the baseline. The results are shown in Table 3 below. Note that the structures counted as the first recess had a maximum diameter of 8.8 μm. [Table 3]

[0038] (Summary of results) The first recess is 1 mm 2 Test sections 1 and 2, each containing 200 to 2000 depressions, showed significantly greater gas release and coverage, and higher foaming properties compared to the control section where no first depressions were observed. The number of second depressions was 1 mm. 2 Test plot 2, with a value of 7,000 to 15,000 per unit area, showed even higher foaming properties. [Explanation of Symbols]

[0039] 1. Resin layer 2 wax

Claims

1. A method for manufacturing a can for a sparkling beverage having an upper surface, a lower surface, and a body portion, comprising: step A: applying a paint containing a resin and a wax to an inner surface of the body portion or an area to become the inner surface of the body portion; and step B: heat-treating the applied paint to form a resin layer and release the wax, the method comprising the steps of: Resin and and 7 to 40 parts by mass of wax having an average particle size of 1 to 15 μm and capable of being desorbed in the step B to form recesses in the resin layer, relative to 100 parts by mass of non-volatile components (excluding wax) in the coating material. Paint for coating the inside of sparkling beverage cans.

2. The coating material for coating the inner surface of cans for carbonated beverages according to claim 1, wherein the wax has an average particle size of 2 to 10 μm.

3. The paint for coating the inner surface of a can for a sparkling beverage according to claim 1 or 2, comprising 10 to 40 parts by mass of the wax.

4. The paint for coating the inner surface of a can for a sparkling beverage according to any one of claims 1 to 3, wherein the softening point of the wax is 90 to 160°C.

5. The paint for coating the inner surface of a can for a sparkling beverage according to any one of claims 1 to 4, wherein the wax comprises at least one wax selected from the group consisting of carnauba wax and polyethylene wax.

6. The paint for coating the inner surface of a can for a sparkling beverage according to any one of claims 1 to 4, wherein the wax comprises a polyethylene wax.

7. The coating material for coating the inner surface of a can for a sparkling beverage according to any one of claims 1 to 6, wherein the resin comprises at least one resin selected from the group consisting of an epoxy resin, an acrylic resin, a polyester resin, and a urethane resin.

8. A sparkling beverage can having a top surface, a bottom surface, and a body portion, A can for a sparkling beverage, comprising, on an inner surface of the body, a resin layer formed from the paint for coating the inner surface of a can for a sparkling beverage according to any one of claims 1 to 7.

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