Method for manufacturing reusable containers and reusable containers

Abstract

To provide a method for making a container easier to reuse.SOLUTION: There is provided a method for manufacturing a reusable container from a used container. The method comprises: a dissolving process; and a reforming process, and the method is configured in that: the used container has a container body and a used coating layer; the used coating layer is formed on a surface of the container body; the reusable container has the container body and a coating layer; the coating layer is formed on the surface of the container body; in the dissolving process, the container body is obtained by attaching a solvent to the used container and dissolving the used coating layer; and in the reforming process, the coating layer is formed on a surface of the container body that has undergone the dissolving process to manufacture the reusable container.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a reusable container and a reusable container.

Background Art

[0002] Patent Document 1 discloses a method for collecting used containers and sorting containers with foreign substances such as color and dirt attached thereto and containers without such foreign substances attached thereto.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the method described in Patent Document 1, containers with foreign substances attached thereto are used as recycled resources or fuel (thermal recycling), and containers without such foreign substances attached thereto are used as reusable containers. From the perspective of environmental load, it is preferable to use the collected used containers as reusable containers. However, depending on, for example, the contents of the container, even if washing and sterilization are performed, it may be difficult to completely remove foreign substances and use the container as a reusable container.

[0005] The present invention has been made in view of such circumstances and aims to facilitate the reuse of containers.

Means for Solving the Problems

[0006] The present invention provides a method for manufacturing a reusable container from a used container, comprising a dissolution step and a reshaping step, wherein the used container has a container body and a used coating layer, the used coating layer being formed on the surface of the container body, the reusable container has a container body and a coating layer, the coating layer being formed on the surface of the container body, the dissolution step involves applying a solvent to the used container to dissolve the used coating layer and obtain the container body, and the reshaping step involves forming the coating layer on the surface of the container body obtained through the dissolution step to manufacture the reusable container.

[0007] In this invention, during the dissolution process, the used coating layer can be dissolved and easily removed along with foreign matter, etc. Then, during the reforming process, a coating layer can be formed again on the surface of the container body, and the container body can be protected again by the coating layer. For this reason, this invention makes it possible to reuse containers.

[0008] The following are examples of various embodiments of the present invention. The embodiments shown below can be combined with each other. Preferably, the coating layer is made of shellac, and a method is provided. Preferably, the solvent is an alcohol solution or an alkaline aqueous solution, and a method is provided. Preferably, the method further comprises a thermosetting step, in which the reusable container manufactured in the reshaping step is heated to a predetermined temperature or higher to thermoset the coating layer.

[0009] According to another aspect of the embodiments of the present invention, a reusable container is provided, comprising a container body and a coating layer, wherein the container body is made of a non-biodegradable resin and the coating layer is formed on the surface of the container body and is made of shellac. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1A is a schematic front view showing a reusable container 1 according to an embodiment. Figure 1B is an enlarged cross-sectional view of the portion of area B shown in Figure 1A. [Figure 2] Figure 2 schematically shows how a used container 1t is immersed in solvent 11A in tank 11 during the dissolution process. [Figure 3] Figure 3A is a schematic cross-sectional view showing foreign matter d1 to d3 adhering to the used coating layer 3t of a used container 1t. Figure 3B is a schematic cross-sectional view showing the container body 2 after the used coating layer 3t (see Figure 3A) has been removed through the dissolution process. [Figure 4] Figure 4 schematically shows how the container body 2 is immersed in the coating solution 12A in the tank 12 during the reshaping process. [Modes for carrying out the invention]

[0011] Embodiments of the present invention will be described below. The various features shown in the embodiments below can be combined with each other.

[0012] 1. Description of the structure of reusable container 1 As shown in Figures 1A and 1B, the reusable container 1 comprises a container body 2 and a coating layer 3. In this embodiment, the reusable container 1 is a bottle, and the reusable container 1 has an internal space 1a for containing contents. The user can reuse the container body 2 by removing and reforming the coating layer 3.

[0013] The container body 2 is the main body (main material) of the reusable container 1 and is made of resin. The resin that makes up the container body 2 can be, for example, a non-biodegradable resin, and can be made of polypropylene, polyester resin, ABS resin (acrylonitrile butadiene styrene resin), or PC resin (polycarbonate resin). The manufacturing method of the container body 2 is not particularly limited and can be manufactured by, for example, direct blow molding, injection blow molding, or injection molding.

[0014] The coating layer 3 is formed on the surface of the container body 2 and is configured to protect the container body 2. In the embodiment, the coating layer 3 is formed on both the inner and outer surfaces of the container body 2. In the embodiment, the area where the coating layer 3 is formed is the entire surface of the container body 2, but is not limited to this, and may be formed only on the inner surface or only on the outer surface. Because the coating layer 3 protects the inner surface of the container body 2, even when contents are placed in the reusable container 1, it is possible to effectively suppress the adhesion of dirt to the container body 2 itself and the transfer of color and odor. In addition, because the coating layer 3 protects the outer surface of the container body 2, the container body 2 is less likely to be scratched, and it is possible to prevent foreign matter such as film and adhesive from directly adhering to the surface of the container body 2.

[0015] Coating layer 3 is composed of shellac. Shellac is a biodegradable natural polymer obtained by purifying the dendritic substance secreted by the lac insect on trees. Furthermore, as will be explained in the manufacturing method of the reusable container 1 described later, shellac can be dissolved with a specific solvent. Therefore, even if the container contains contents that are difficult to clean or adhesives that are difficult to remove are attached to the outer surface, the shellac layer (coating layer 3) can be removed together with the solvent. In other words, the reusable container 1 has a structure that is excellent in terms of cleaning foreign matter.

[0016] The thickness (μm) of the coating layer 3 is specifically, for example, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, and it may also be within the range between any two of the values exemplified herein. By having the coating layer 3 be the values exemplified herein or within the range of the values exemplified herein, it is easy to achieve both the protection of the container body 2 and the removability of the coating layer 3 by a solvent. Also, it is possible to suppress the coating layer 3 from being highly visible in color.

[0017] 2. Method for manufacturing the reusable container 1 The method for manufacturing the reusable container 1 includes a recovery step, a melting step, a solvent cleaning step, and a reforming step. By repeating these series of steps, the container body 2 will be reused. Although the explanation is omitted here, the container body 2 (new container body 2) will be manufactured in a container body manufacturing process separately from these series of steps. And after the coating layer 3 is formed on the surface of the container body 2, for example, it will be distributed in the market and recovered in the above-mentioned recovery step as the used container 1t. Each step will be described below.

[0018] 2-1 Recovery step In the recovery step, the used container 1t used by users, etc. is recovered. Before the next melting step, it is preferable that the used container 1t has been pre-treated. The pre-treatment is, for example, an operation such as removing the film with product descriptions, etc. attached to the used container 1t and removing a certain amount of the contents attached to the used container 1t. Thereby, it is possible to suppress foreign matter from accumulating in the tank 11 used in the melting step. Note that the pre-treatment is not an essential step and may not be carried out.

[0019] 2-2 Melting step In the dissolution step shown in FIG. 2, a solvent is attached to the used container 1t to dissolve the used coating layer 3t shown in FIG. 3A. In the embodiment, the used container 1t is immersed in a tank 11 in which the solvent 11A is stored. Thereby, the solvent evenly spreads over the entire surface of the used container 1t, removes the coating layer 3 from the container body 2, and a container body 2 (see FIG. 3B) from which the used coating layer 3t has been removed can be obtained.

[0020] As the solvent used in the dissolution step, for example, an alkaline aqueous solution or a lower alcohol solution can be employed. Specifically, as the alkaline aqueous solution, an aqueous sodium hydroxide solution or an aqueous potassium hydroxide solution can be employed. The alkaline aqueous solution may be at room temperature (for example, 15°C to 35°C). The pH of the alkaline aqueous solution is, for example, 10 to 14, specifically, for example, 10.0, 10.5, 11.0, 11.5, 12.0, 12.5, 13.0, 13.5, 13.55, 13.60, 13.65, 13.70, 13.75, 13.80, 13.85, 13.90, 13.95, 14.0, and may be within the range between any two of the values exemplified herein. Preferably, the pH of the alkaline aqueous solution is 13 or more.

[0021] Also, as the lower alcohol solution, an ethanol solution can be employed. The concentration (wt%) of the ethanol solution is specifically, for example, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, and may be within the range between any two of the values exemplified herein.

[0022] As an example, the used coating layer 3t shown in Figure 3A has stains d1 to d3 formed on it. Stain d1 is dirt adhering to the surface of the used coating layer 3t that could not be completely removed by the pretreatment described above. Stain d2 is dirt formed when contents penetrate into the coating layer 3 and stain the coating layer 3. Stain d3 is adhesive adhering to the surface of the used coating layer 3t that could not be completely removed by the pretreatment described above. In the dissolution process, the used coating layer 3t itself is removed using a solvent. Therefore, not only foreign matter that adheres firmly to the surface, such as stains d1 and d3, but also stains like d2 that have seeped in can be easily removed.

[0023] In this embodiment, the used container 1t was described as being immersed in a tank 11 where the solvent 11A is stored, but the invention is not limited to this. For example, the solvent 11A may be applied to the used container 1t by spraying it. Furthermore, the used coating layer 3t will flow into the tank 11, but the shellac that makes up this flowed-out used coating layer 3t may be recovered and purified. This allows the recovered and purified shellac to be reused in the reforming process described later, further improving the resource recyclability (resource reuseability) of the manufacturing process of the reusable container 1.

[0024] 2-3 Solvent cleaning process In the solvent cleaning process, the container body 2, from which the used coating layer 3t has been removed, is taken out of the tank 11 shown in Figure 2. When taking it out, it is preferable to turn the container body 2 downwards so that the solvent inside can be discharged from the container body 2. Since solvent may be adhering to the surface of the container body 2, the container body 2 is washed with water, for example, in the solvent cleaning process. In addition, the manufacturing method of the reusable container 1 may include a step to remove moisture from the container body 2 (drying step) after the solvent cleaning process and before the subsequent reforming step.

[0025] 2-4 Reshaping process In the reforming process, a coating layer 3 is formed on the surface of the container body 2 to produce the reusable container 1 shown in Figures 1A and 1B. In the reforming process, the coating layer 3 is formed on both the outer and inner surfaces of the container body 2. In this embodiment, the container body 2 is immersed in a tank 12 in which a coating solution 12A containing shellac is stored. This causes the coating solution 12A to adhere to the entire surface of the container body 2. The coating solution 12A can be obtained, for example, by dissolving shellac in a lower alcohol (e.g., ethanol). The shellac concentration (wt%) of coating solution 12A is specifically, for example, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, and may also be within the range of any two of the values ​​exemplified here.

[0026] Once the coating solution 12A has spread over the surface of the container body 2, the container body 2 is removed from the tank 12 and dried at room temperature (for example, 15°C to 35°C). This allows the alcohol component to evaporate, forming a coating layer 3 composed of shellac on the surface of the container body 2. Note that air may be supplied (blown) to accelerate the drying process.

[0027] The process of applying the coating solution 12A to the container body 2 and the process of drying the coating solution 12A may be repeated. This makes it easier to form a coating layer 3 of the desired thickness on the container body 2. Furthermore, while the embodiment describes an example in which the container body 2 is immersed in a tank 12 in which the coating solution 12A is stored, the embodiment is not limited to this. For example, the coating solution 12A may be applied to the container body 2 by spraying it. When spraying, the shellac concentration of the coating solution 12A should be set to, for example, 10 to 20 wt%. Also, when the container body 2 is immersed in the tank 12 as in the embodiment, the concentration may be higher, for example, it can be set to 10 to 50 wt%.

[0028] 3. Operation and Effects of the Embodiments In the dissolution process according to the embodiment, the used coating layer 3t can be dissolved and easily removed together with the used coating layer 3t, for example, foreign matter. Since the used coating layer 3t, which has absorbed the odor and color of the contents, is dissolved by the solvent, the container body 2 can be reused even if contents that could not be reused in the conventional container 1 due to poor cleanability are sealed inside the reuse container 1. In addition, because the coating layer 3 is applied to the outer surface of the container body 2, difficult-to-remove seals, labels, and adhesives can be peeled off simultaneously with the used coating layer 3t. Furthermore, because the coating layer 3 is applied to the outer surface of the container body 2, scratches on the design surface of the container body 2 can be effectively suppressed.

[0029] Furthermore, in the reforming process, a coating layer 3 can be formed again on the surface of the container body 2, and the container body 2 can be protected again by the coating layer 3. Since the shellac that constitutes the coating layer 3 is biodegradable, this embodiment can reduce the environmental impact. In addition, the reformed shellac layer (coating layer 3) may be used as food and is harmless even if ingested. Moreover, since the removal and reforming of the shellac layer (coating layer 3) can be carried out repeatedly, the container body 2 can be reused many times until it deteriorates over time.

[0030] When reusing conventional containers that do not have a coating layer 3, the containers may be cleaned using, for example, strong alkaline hot water. However, in this embodiment, shellac is used as the coating layer 3. Therefore, the used coating layer 3t and dirt can be removed under mild conditions such as an alkaline aqueous solution or a lower alcohol solution at room temperature. As a result, deformation of the container body 2 can be suppressed, and the environmental burden of the dirt cleaning process (dissolution process in this embodiment) can be reduced.

[0031] 4. Variations 4-1 Modification 1: Thermosetting process In the embodiment, the coating layer 3 is described as being dried at room temperature, but the invention is not limited to this. After applying the coating solution 12A to the container body 2, the shellac may be heat-cured at a predetermined time and temperature. This heat-curing step can be carried out, for example, by placing the container body 2 coated with the coating solution 12A into an oven. This heat-curing step can also be carried out after the reforming step. The predetermined time (minutes) could be, for example, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, 350, 360, 370, 380, 390, 400, 410, 420, or within the range of any two of the numbers exemplified here. The predetermined temperatures (°C) are, for example, 110, 112, 114, 116, 118, 120, 122, 124, 126, 128, and 130, and may also be within the range of any two of the values ​​exemplified here.

[0032] Furthermore, as in this modified example 1, when the coating layer 3 is heat-cured, it is preferable to keep the temperature of the solvent used in the dissolution process higher than room temperature. Specifically, the solvent temperature (°C) can be, for example, 50, 52, 54, 56, 58, 60, 62, 64, 66, 68, or 70, and may be within the range of any two of the values ​​exemplified here. In addition, for example, if the container body 2 is made of a heat-resistant resin, the temperature of the solvent used may be further increased according to its heat resistance temperature.

[0033] 4-2 Modification 2: Coating layer 3 is composed of calcium alginate In the embodiments described, the coating layer 3 is made of shellac, but it is not limited to this. For example, calcium alginate may be used as the constituent material of the coating layer 3. For example, calcium alginate may be obtained by reacting an aqueous sodium alginate solution with an aqueous calcium solution (e.g., an aqueous calcium chloride solution) and used as the constituent material of the coating layer 3.

[0034] 5 Examples Tests were conducted to see if foreign substances with strong odors and colors could be removed from test plates coated with shellac using various cleaning solutions. The conditions were as follows:

[0035] 5-1 Test plate, coating solution, contents, and cleaning solution Test plate dimensions: 15mm x 60mm x approximately 2mm, PP (FH3315, Sumitomo Chemical, Noblen) Test plate 1: Blank (the test plate itself, without the formation of coating layer 3) Test plate 2: After applying the shellac coating solution to the test plate, dry it at room temperature (23°C). Test plate 3: After applying the shellac coating solution to the test plate, heat it in an oven at 120°C for 5 hours. Coating solution: General-purpose purified shellac GSN (Gifu Cerac Manufacturing Co., Ltd.) 20 wt% EtOH solution (Note that shellac is the same as shellac as used herein.) Contents: A mixture of ketchup and salad oil. Cleaning solution 1: Tap water Washing solution 2: 95 wt% EtOH Washing solution 3: 3 wt% NaOH aq. (at room temperature) Washing solution 4: 3 wt% NaOH aq. (70℃)

[0036] 5-2 Examination Procedure <Test plate coating> (1) Measure the weight of the test plate. (2) Roughen the surface of the test plate with 120-grit sandpaper. This is to ensure that the blank test plate is stained with the contents. The blank test plate is a comparative example test plate in which coating layer 3 is not formed. (3) Immerse 3 / 4 of the test plate in the coating solution and then remove it. Repeat this process 10 times. (4) Hang it up overnight at 23°C and let it dry. (5) Measure the weight and calculate the amount of shellac to be applied from the difference between the weight of the test plate and the weight of the test plate.

[0037] <Stain resistance and cleaning test> (1) Test plates 1 to 3 were immersed in the contents and left standing at 40°C for 7 days. (2) After that, test plates 1 to 3 were removed and immersed in cleaning solutions 1 to 4 for 8 hours. The results are shown in Table 1 below. Table 1 shows whether the foreign matter (in this case, ketchup components) attached to the test plates was removed from the test plates.

[0038] [Table 1]

[0039] 5-3 Test Results When test plate 1 (blank) was immersed in cleaning solutions 1, 3, and 4, the test plate became discolored. When cleaned with cleaning solution 2, the discoloration was slightly suppressed compared to cleaning solution 1, etc. However, in actual products, the contact time between the contents and the main material (test plate) is even longer, so in actual products, cleaning solution 2 may not be able to completely clean the test plate. In contrast, with respect to test plate 2, the coating layer 3 to which the ketchup was attached dissolved along with the ketchup in all four cleaning solutions (2 to 4), resulting in no discoloration. However, the coating layer 3 did not dissolve in tap water. Furthermore, regarding test plate 3, even after immersion in cleaning solution 2 for 8 hours, it was still partially dissolved due to the heat-curing action of shellac. In other words, some of the coating layer 3 remained on test plate 3 along with the ketchup. It is thought that dissolution may be possible by measures such as increasing the immersion time in cleaning solution 2, raising the temperature of cleaning solution 2, or replacing cleaning solution 2. Also, for cleaning solutions 3 and 4, there was no discoloration because the coating layer 3 with the ketchup attached dissolved together with the ketchup. In this way, the effects of the embodiment could be confirmed by exposing test plates 2 and 3 to cleaning solutions 2 to 4. In addition to the test plates, the same experiment was conducted on test bottles coated with shellac, and the same effect was confirmed. [Explanation of Symbols]

[0040] 1: Reusable container 1a: Internal space 1t: Used container 2: Container body 3: Coating layer 3t: Used coating layer 11: Tank 11A: Solvent 12: Tank 12A: Coating solution

Claims

1. A method for manufacturing reusable containers from used containers, The process comprises a dissolution step, a reforming step, and a thermosetting step. The aforementioned used container comprises a container body and a used coating layer. The used coating layer is formed on the surface of the container body, The aforementioned reusable container comprises the container body and a coating layer made of shellac. The coating layer is formed on the surface of the container body, In the dissolution step, the used container body is obtained by applying a solvent to the used container and dissolving the used coating layer. In the reforming step, the coating layer is formed on the surface of the container body that has undergone the dissolution step to manufacture the reusable container. In the aforementioned thermosetting step, the reusable container manufactured in the reforming step is heated to a predetermined temperature or higher to thermoset the coating layer.

2. The method according to claim 1, The aforementioned used coating layer is composed of shellac that has been heated and cured at a predetermined temperature or higher. The method wherein the solvent is an alkaline aqueous solution.

3. The method according to Claim 1 or Claim 2, A method wherein the heating temperature in the heat curing step is 110 to 130°C.

4. A method according to any one of Claims 1 to 3, A method wherein the heating time in the heat curing step is 60 to 420 minutes.

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