Insulated container

Abstract

To provide a heat insulating container excellent in heat insulating properties, visibility and heat resistance though it is made of a resin based on a polyolefin.SOLUTION: According to the present invention, there is provided a heat-insulating container including a container body, wherein the container body includes an inner container and an outer container disposed so as to cover the inner container, and a sealed space is provided between the inner container and the outer container, the inner container is made of a resin containing 60% by mass or more of a homopolymer of propylene, the outer container is made of a resin containing 60% by mass or more of a random copolymer of propylene and another olefin, the gas in the sealed space contains a gas having a lower thermal conductivity than air, and the air pressure in the sealed space is 0.5 to 1.5 atm.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a heat-insulating container.

Background Art

[0002] Patent Document 1 discloses a heat-insulating container in which an inner container and an outer container are arranged with a gap therebetween and integrally joined.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In some cases, it is desirable to form a heat-insulating container mainly from a resin based on polyolefin from the viewpoints of moldability and material cost. However, since polyolefin has lower transparency and heat resistance than PET, a heat-insulating container in which the inner container and the outer container are formed of polyolefin has problems such as low visibility of the contents and easy deformation under a high-temperature environment.

[0005] The present invention has been made in view of such circumstances, and provides a heat-insulating container that is made of a resin mainly based on polyolefin and has excellent heat insulation, visibility, and heat resistance.

Means for Solving the Problems

[0006] According to the present invention, the following inventions are provided. [1] An insulated container comprising a container body, wherein the container body comprises an inner container and an outer container disposed to cover the inner container, a sealed space is provided between the inner container and the outer container, the inner container is made of a resin containing 60% by mass or more of a homopolymer of propylene, the outer container is made of a resin containing 60% by mass or more of a random copolymer of propylene and other olefins, the gas in the sealed space contains a gas with a lower thermal conductivity than air, and the atmospheric pressure in the sealed space is 0.5 to 1.5 atmospheres. An insulated container as described in [2][1], wherein the thickness of the inner container is 0.5 to 1.5 mm at the center of the height of the container body, and the thickness of the outer container is 1.0 to 2.0 mm. An insulated container according to [3] [1] or [2], wherein the total proportion of argon gas, krypton gas, and xenon gas in the sealed space is 50% by volume or more. [Effects of the Invention]

[0007] Through diligent research, we discovered that the above-described insulated container, while primarily made of polyolefin resin, exhibits excellent heat insulation, visibility, and heat resistance, leading to the completion of this invention. [Brief explanation of the drawing]

[0008] [Figure 1] This is a front view of the container body 1 of the insulated container 10 of one version of the present invention. [Figure 2] This is a longitudinal cross-sectional view of the container body 1 in Figure 1, passing through the central axis C. [Figure 3] This is a magnified view of region A in Figure 2. [Figure 4] This figure corresponds to Figure 3 in Reference Example 1. [Figure 5] This is an explanatory diagram of the grinding process for grinding the area 2i of the inner container 2 that is scheduled to be laser-welded. [Figure 6]Figure 6A is a magnified view of area A in Figure 5. Figure 6B shows the grinding tool 5 being pressed against the area 2i to be laser-welded, grinding the protruding portion 2i1 that constitutes the area 2i to be laser-welded. Figure 6C shows the state after grinding is complete and the grinding tool 5 has been removed from the area 2i to be laser-welded. [Modes for carrying out the invention]

[0009] Embodiments of the present invention will be described below. The various features shown in the embodiments below can be combined with each other. Furthermore, each feature constitutes an independent invention. In addition, elements not specified in the claims in the embodiments below are optional and can be omitted. Any number of zeros (for example, one or two) may be added to the end of the numerical values ​​disclosed in the following description. For example, one or two zeros may be added after "1.4" to make it "1.40" or "1.400".

[0010] An embodiment of the present invention, a heat-insulating container 10, and a method for manufacturing the same will be described with reference to Figures 1 to 6. The embodiments shown below include inventions in at least the following aspects.

[0011] The invention from the first perspective is, An insulated container 10 comprising a container body 1, The container body 1 comprises an inner container 2 and an outer container 3 arranged to cover the inner container 2. A sealed space 4 is provided between the inner container 2 and the outer container 3. The inner container 2 is made of a resin containing 60% by mass or more of a propylene homopolymer. The outer container 3 is made of a resin containing 60% by mass or more of a random copolymer of propylene and other olefins. The gas in the sealed space 4 contains a gas with a lower thermal conductivity than air. The air pressure in the sealed space 4 is 0.5 to 1.5 atmospheres, and it is an insulated container 10.

[0012] The invention from the second perspective is, A method for manufacturing the container body 1 of the heat-insulating container 10, comprising a molding step, a grinding step, and a laser welding step, in the molding step, the inner container 2 and the outer container 3 are each molded, in the grinding step, at least one of the inner container 2 and the outer container 3 is ground at a laser welding planned site 2i which is a site where laser welding is to be performed, in the laser welding step, the inner container 2 and the outer container 3 are laser welded at the laser welding planned site 2i. This is the method.

[0013] The invention of the third aspect is, a heat-insulating container 10 including a container body 1, the container body 1 includes an inner container 2 and an outer container 3 disposed so as to cover the inner container 2, a sealed space 4 is provided between the inner container 2 and the outer container 3, the inner container 2 includes a mouth portion 2a and a body portion 2g having an outer diameter larger than that of the mouth portion 2a, the body portion 2g includes a shoulder portion 2g1 whose outer diameter increases as it moves away from the mouth portion 2a, and a reduced diameter portion 2g5 that is continuous with the outer edge 2g4 of the shoulder portion 2g1 and whose outer diameter decreases as it moves away from the mouth portion 2a, when the outer diameter of the inner container 2 at the outer edge 2g4 is D1 and the radius of curvature of a portion 2g8 of the shoulder portion 2g adjacent to the outer edge 2g4 is R1, it is a heat-insulating container in which R1 / D1 is 0.10 or more.

[0014] 1. Structure of the heat-insulating container 10 The heat-insulating container 10 is preferably a refillable bottle that is repeatedly filled with and used for contents. Examples of the contents of the heat-insulating container 10 include water, tea, soft drink water, carbonated beverages, and the like.

[0015] The insulated container 10 comprises a container body 1. The container body 1 comprises a mouth portion 1a, a body portion 1b, and a bottom portion 1c. The container body 1 is preferably bottle-shaped. In the following description, "top" or "bottom" refers to the "top" or "bottom" when the container body 1 is upright with the bottom portion 1c facing downwards, unless otherwise specified.

[0016] As shown in Figures 2 and 3, the container body 1 comprises an inner container 2 and an outer container 3 positioned to cover the inner container 2.

[0017] The inner container 2 is a bottomed cylindrical container, and the contents are housed inside it. The inner container 2 comprises a mouth portion 2a, a body portion 2g, and a bottom portion 2f. The mouth portion 2a becomes the mouth portion 1a of the container body 1. The mouth portion 2a is provided with an engaging portion 2c to which a cap (not shown) can be attached. The cap may be screw-type or press-fit type. The outer diameter at the opening end of the mouth portion 2a is, for example, 20 to 50 mm (33 mm in this embodiment), preferably 25 to 45 mm, and more preferably 30 to 40 mm.

[0018] The body portion 2g has a larger outer diameter than the mouth portion 2a (in this specification, "outer diameter" means the equivalent diameter of a circle if the cross-section is not circular). The body portion 2g is cylindrical, and the bottom portion 2f is provided at the lower end of the body portion 2g, closing the lower end of the body portion 2g. The body portion 2g includes a shoulder portion 2g1 whose outer diameter increases as it moves away from the mouth portion 2a, and a reduced diameter portion 2g5 which is connected to the outer edge 2g4 of the shoulder portion 2g1 and whose outer diameter decreases as it moves away from the mouth portion 2a. If the outer diameter of the inner container 2 at the outer edge 2g4 of the shoulder portion 2g1 is D1, and the radius of curvature of the portion 2g8 of the shoulder portion 2g1 adjacent to the outer edge 2g4 is R1, then it is preferable that R1 / D1 is 0.10 or more (0.15 in this embodiment). In the embodiment of Reference Example 1, R1 / D1 is 0.06.

[0019] In Reference Example 1 shown in Figure 4, when attempting to weld the inner container 2 and outer container 3 together by pressing the opening 2a of the inner container 2 downwards to bring them into close contact, the inner container 2 deforms so that the shoulder portion 2g1 rotates around the outer edge 2g4 of the shoulder portion 2g1 as a pivot point, as indicated by arrow X. This makes it difficult for the pressing force applied to the opening 2a to be transmitted to the area 2l that brings the inner container 2 and outer container 3 into close contact, making defects in the welding of the inner container 2 and outer container 3 more likely.

[0020] In this embodiment, as shown in Figure 3, D1 is the same as in Reference Example 1, but R1 is larger than in Reference Example 1, resulting in a larger R1 / D1 ratio than in Reference Example 1. The larger R1 / D1 ratio, the less likely deformation is to occur where the shoulder portion 2g1 rotates around the outer edge 2g4 as a pivot point. In this embodiment, since R1 / D1 is a relatively large value of 0.10 or more, the rotation of the shoulder portion 2g1 around the outer edge 2g4 as a pivot point is suppressed, and as a result, welding defects between the inner container 2 and the outer container 3 are suppressed. R1 / D1 is, for example, 0.10 to 0.50, specifically, for example, 0.10, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45, 0.50, and may be within the range of any two of the values ​​exemplified here, or greater than or equal to either of them.

[0021] D1 is, for example, 50 to 80 mm (66.5 mm in this embodiment), and preferably 60 to 70 mm. Specifically, D1 may be, for example, 50, 55, 60, 65, 70, 75, or 80 mm, and may be in a range between any two of the values ​​exemplified here. R1 is, for example, 5 to 30 mm (10 mm in this embodiment), and preferably 8 to 15 mm. Specifically, R1 may be, for example, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30 mm, and may be in a range between any two of the values ​​exemplified here.

[0022] The shoulder portion 2g1 has an inclination angle α of 10 to 60 degrees (30 degrees in this embodiment) at the point 2g6 where the inclination angle with respect to the plane P1 perpendicular to the central axis C of the mouth portion 2a is minimized. In this case, the rotation of the shoulder portion 2g1 with the outer edge 2g4 as the pivot point is suppressed compared to Reference Example 1 where the inclination angle α is 4 degrees. The inclination angle α is preferably 20 to 45 degrees, specifically, for example, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, and 60 degrees, and may be in the range between any two of the values ​​exemplified here. As shown in Figure 3, if D2 is the radial length from the base 2d of the mouth portion 2a to the outer edge 2g4, and D3 is the radial length of the part of the shoulder portion 2g1 where the inclination angle is constant, then D3 / D2 is, for example, 0.30 to 0.90 (0.63 in this embodiment), and preferably 0.45 to 0.75. Specifically, D3 / D2 could be, for example, 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, 0.60, 0.65, 0.70, 0.75, 0.80, 0.85, or 0.90, or any range between any two of the numbers exemplified here.

[0023] It is preferable that the shoulder portion 2g1 and the reduced diameter portion 2g5 are connected in a curved shape. In this case, thinning and damage to the outer edge 2g4 are suppressed compared to Reference Example 1 in which the outer edge 2g4 has a pointed shape. It is preferable that the reduced diameter portion 2g5 is curved so as to be convex outward. In this case, thinning and damage to the outer edge 2g4 are suppressed compared to Reference Example 1 in which the reduced diameter portion 2g5 is flat. The inclination angle β of the reduced diameter portion 2g5 with respect to the central axis C is, for example, 15 to 75 degrees (45 degrees in this embodiment), and preferably 30 to 60 degrees. Specifically, the inclination angle β is, for example, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75 degrees, and may be in the range between any two of the values ​​exemplified here. The reduced diameter portion 2g5 faces the open end 3a of the outer container 3. The reduced diameter portion 2g5 may or may not be in contact with the open end 3a. Preferably, the outer diameter at the outer edge 2g4 matches the outer diameter at the open end 3a. In this case, the appearance of the heat-insulating container 10 is particularly excellent. In Figure 3, a gap is provided between the reduced diameter portion 2g5 and the open end 3a. The gap between the reduced diameter portion 2g5 and the open end 3a at the center of the thickness direction of the open end 3a is preferably 10 mm or less (1.4 mm in this embodiment), and more preferably 5 mm or less. Specifically, this gap may be, for example, 0, 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 7, 8, 9, 10 mm, or it may be in the range between any two of the values ​​exemplified here.

[0024] Furthermore, in this embodiment, compared to Reference Example 1, the curvature of the inner container 2 near the outer edge 2g4 is gentler, making it easier to clean the inside of the inner container 2. Also, in this embodiment, compared to Reference Example 1, the inclination angle β of part 2g6 is larger, so when the insulated container 10 is tilted to discharge the contents, the contents are less likely to remain inside the insulated container 10.

[0025] The torso 2g is provided with a torso body 2g2 located on the bottom 2f side of the shoulder 2g1. The torso body 2g2 has a shape in which the outer diameter is substantially constant toward the bottom 2f, or a shape in which the diameter decreases toward the bottom 2f. The bottom 2f is provided with a pair of parallel grooves 2f1. Both ends of each groove 2f1 face toward the mouth 2a. A protrusion 2f2 is formed between the pair of grooves 2f1. Both ends of the protrusion 2f2 face toward the mouth 2a. With this configuration, the bottom 2f is reinforced by the grooves 2f1 and the protrusion 2f2, and deformation of the bottom 2f is suppressed.

[0026] As shown in Figure 2, the outer container 3 is a bottomed cylindrical shape, and the parts of the body 2g2 other than the reduced diameter portion 2g5 and the bottom portion 2f are housed inside the outer container 3. The outer container 3 comprises a cylindrical body portion 3d and a bottom portion 3e that closes the lower end of the body portion 3d. The shoulder portion 2g1, the reduced diameter portion 2g5 and the body portion 3d become the body portion 1b of the container body 1, and the bottom portion 3e becomes the bottom portion 1c of the container body 1.

[0027] The body 3d of the outer container 3 comprises, in order from the open end 3a side, an upper body 3d1, a central body 3d2, and a lower body 3d3. The upper body 3d1 and the lower body 3d3 are each curved so as to be convex inward, while the central body 3d2 is curved so as to be convex outward. A stepped portion 3d4 is provided between the central body 3d2 and the upper body 3d1, with the central body 3d2 on the inside (i.e., the side closer to the central axis C of the container body 1; the same applies hereinafter). A stepped portion 3d5 is provided between the central body 3d2 and the lower body 3d3, with the central body 3d2 on the inside. The rigidity of the body 3d is increased by these curved shapes and stepped portions.

[0028] As shown in Figure 3, the body 2g2 of the inner container 2 is provided with a diameter-reducing portion 2g7 that decreases in diameter as it moves away from the shoulder portion 2g1, and is connected to the diameter-reducing portion 2g5. The body 3d of the outer container 3 is provided with a diameter-expanding portion 3d6 adjacent to the opening end 3a, which expands in diameter toward the opening end 3a. When the inner container 2 is inserted into the outer container 3, the outer surface of the diameter-reducing portion 2g7 comes into contact with the inner surface of the diameter-expanding portion 3d6, so it is preferable to join these portions to form a joint portion 3b.

[0029] When the inner container 2 and outer container 3 are made of thermoplastic resin, the joining at the joint 3b is preferably done by welding. Examples of welding methods include ultrasonic welding and laser welding.

[0030] By joining the inner container 2 and the outer container 3 at the joint 3b, a sealed space 4 is formed between the inner container 2 and the outer container 3. If the sealed space 4 is a depressurized space or contains a gas with a lower thermal conductivity than air (hereinafter referred to as "low thermal conductivity gas," e.g., krypton gas (Kr), argon gas (Ar), xenon gas (Xe)), the thermal conductivity of the sealed space 4 decreases, and the thermal insulation of the insulated container 10 increases.

[0031] Preferably, the gas in the sealed space 4 contains a low thermal conductivity gas, and the atmospheric pressure in the sealed space 4 is 0.5 to 1.5 atmospheres. In this case, since the pressure difference between the sealed space 4 and the outside space is relatively small, deformation of the outer container 3 due to the pressure difference can be suppressed. The atmospheric pressure in the sealed space 4 is preferably 0.8 to 1.2 atmospheres, specifically, for example, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, and 1.5 atmospheres, and may be in the range between any two of the values ​​exemplified here. The total proportion of argon gas, krypton gas, and xenon gas in the sealed space 4 is preferably 50% by volume or more. In this case, the thermal conductivity of the sealed space 4 tends to be particularly low. This percentage is, for example, 50-100% by volume, specifically, for example, 50, 60, 70, 80, 90, 95, 99, 99.9, and 100% by volume, and may also be in the range between any two of the values ​​exemplified here.

[0032] The inner container 2 and outer container 3 are preferably made of thermoplastic resin such as PET or polyolefin. The inner container 2 and outer container 3 can be formed by blow molding. The blow molding may be direct blow molding or injection blow molding. In direct blow molding, a molten cylindrical parison extruded from an extruder is sandwiched between a pair of split molds and blown air into the parison to perform blow molding. In this case, an elongated cut-off portion (not shown) is formed at the bottom 3e when the parison is squeezed and cut off by the pair of molds. In injection blow molding, a test tube-shaped bottomed parison called a preform is formed by injection molding, and blow molding is performed using this parison.

[0033] It is preferable that the inner container 2 has higher rigidity (higher tensile modulus) than the outer container 3. In this case, in addition to the inner container 2 being less likely to break due to its own rigidity, the outer container 3 acts as a cushion when the insulated container 10 is dropped, thus suppressing leakage of contents due to damage to the inner container 2. The tensile modulus of the inner container 2 is, for example, 1500 to 2500 MPa. Specifically, this value is, for example, 1500, 1600, 1700, 1800, 1900, 2000, 2100, 2200, 2300, 2400, and 2500 MPa, and may be in the range between any two of the values ​​exemplified here. The tensile modulus of the outer container 3 is, for example, 200 to 1000 MPa. Specifically, these values ​​are, for example, 200, 300, 400, 500, 600, 700, 800, 900, and 1000 MPa, and may be within a range between any two of the values ​​exemplified here. The difference in tensile modulus between the inner container 2 and the outer container 3 is preferably 1000 MPa or more, and more preferably 1000 to 2300 MPa. Specifically, these differences are, for example, 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900, 2000, 2100, 2200, and 2300 MPa, and may be within a range between any two of the values ​​exemplified here. In this specification, tensile modulus refers to the measurement value at 25°C. Tensile modulus can be measured in accordance with JIS K 7161-1:2014.

[0034] Incidentally, polyolefins such as polypropylene have superior moldability in direct blow molding compared to PET, so when forming the inner container 2 and outer container 3 by direct blow molding, it is preferable to construct the inner container 2 and outer container 3 from a resin mainly composed of polyolefin. On the other hand, polyolefins have lower transparency and heat resistance compared to PET, so an insulated container 10 in which the inner container 2 and outer container 3 are made of polyolefin has the problem of poor visibility of the contents and being prone to deformation in high-temperature environments.

[0035] To address these issues, it is preferable that the inner container 2 be made of a resin containing 60% by mass or more of a propylene homopolymer (hereinafter referred to as "hPP") (hereinafter referred to as "hPP-based resin"), and the outer container 3 be made of a resin containing 60% by mass or more of a random copolymer of propylene and another olefin (e.g., ethylene) (hereinafter referred to as "rPP") (hereinafter referred to as "rPP-based resin"). If the outer container 3 is made of hPP-based resin, the visibility of the contents of the inner container 2 deteriorates significantly. If both the inner container 2 and the outer container 3 are made of rPP-based resin, the outer container 3 may deform in a high-temperature environment if the air pressure in the sealed space 4 is too low, and if a low-thermal-conductivity gas is filled into the sealed space 4, the inner container 2 is likely to deform due to gas expansion in a high-temperature environment. On the other hand, by filling the sealed space 4 with a low thermal conductivity gas so that the air pressure inside the sealed space 4 is 0.5 to 1.5 atmospheres, and then constructing the inner container 2 from hPP resin and the outer container 3 from rPP resin, it is possible to suppress deformation of the inner container 2 and outer container 3 in high-temperature environments while ensuring heat insulation and visibility of the contents.

[0036] The proportion of hPP in hPP-based resins and the proportion of rPP in rPP-based resins are, for example, 60 to 100% by mass, preferably 70 to 100% by mass, and specifically, for example, 60, 65, 70, 75, 80, 85, 90, 95, and 100% by mass, and may be in the range between any two of the values ​​exemplified here, or greater than or equal to either of them. hPP-based resins may contain other resins other than hPP in layers, or in the form of a mixed resin with hPP. rPP-based resins may contain other resins other than rPP in layers, or in the form of a mixed resin with rPP. Other resins include, for example, gas barrier resins such as EVOH and adhesive resins.

[0037] The inner container 2 preferably comprises an hPP layer made of hPP and a gas barrier layer made of a gas barrier resin, and it is preferable that the gas barrier layer is sandwiched between a pair of hPP layers. The outer container 3 preferably comprises an rPP layer made of rPP and a gas barrier layer made of a gas barrier resin, and it is preferable that the gas barrier layer is sandwiched between a pair of rPP layers. By providing a gas barrier layer, the permeation of gas through the wall surface is suppressed, and thus the decrease in thermal insulation performance due to gas permeation is suppressed. Furthermore, the proportion of other resins other than polypropylene contained in the hPP resin or rPP resin is preferably less than 6% by mass. In this case, the hPP resin or rPP resin can be considered as a single material (monomaterial), which improves recyclability.

[0038] Preferably, at the center of the height direction of the container body 1, the wall thickness of the inner container 2 is 0.5 to 1.5 mm, and the wall thickness of the outer container 3 is 1.0 to 2.0 mm. With such wall thicknesses, it is possible to suppress an increase in the weight of the container body 1 while particularly improving heat insulation, visibility, and heat resistance. Specifically, the wall thickness of the inner container 2 may be, for example, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, or 1.5 mm, and may be within a range between any two of the values ​​exemplified here. Specifically, the wall thickness of the outer container 3 may be, for example, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, or 2.0 mm, and may be within a range between any two of the values ​​exemplified here.

[0039] 2. Manufacturing method of the insulated container 10 The insulated container 10 can be manufactured by attaching a cap to the mouth portion 2a of the container body 1. The container body 1 can be manufactured by molding the inner container 2 and the outer container 3 separately, and then joining the inner container 2 and the outer container 3 to form a joint portion 3b.

[0040] As shown in Figures 5 and 6, the container body 1 is preferably manufactured by a method comprising a molding process, a grinding process, and a laser welding process. Each process will be described below.

[0041] <Forming process> In the molding process, the inner container 2 and the outer container 3 are molded separately. The molding method for the inner container 2 and the outer container 3 is as described above.

[0042] <Grinding process> In the grinding process, as shown in Figures 5 and 6, the laser welding area 2i, which is the area where laser welding is to be performed, is ground on at least one of the inner container 2 and the outer container 3. In this embodiment, the laser welding area 2i on the inner container 2 side is ground, but it may also be configured to grind the laser welding area on the outer container 3 side, or to grind the laser welding area on both the inner container 2 and the outer container 3. This grinding makes the laser welding area 2i suitable for laser welding, thereby suppressing the occurrence of laser welding defects. It is preferable that the laser welding area 2i is provided around the entire circumference of the inner container 2. This grinding is preferably performed by rotating the inner container 2 around the central axis C of the mouth 2a of the inner container 2 while bringing the grinding tool 5 into contact with the laser welding area 2i. In this case, stable grinding is easier to perform. In one example, the rotation of the inner container 2 can be performed by attaching the head 7 of the rotating device to the opening 2a with the bottom 2f supported by the bearing member 6, and then rotating the opening 2a together with the head 7.

[0043] Examples of grinding tools 5 include grinding wheels and cutting tools. It is also preferable that the laser welding area 2i is roughened by grinding. When laser welding is performed with a laser absorbent applied to the laser welding area 2i, roughening the laser welding area 2i can suppress dripping of the laser absorbent if it is in liquid form. The thickness removed by this cutting is, for example, 0.05 to 0.30 mm, specifically, for example, 0.05, 0.10, 0.15, 0.20, 0.25, 0.30 mm, and may be in the range between any two of the values ​​exemplified here.

[0044] As shown in Figure 5, the grinding tool 5 is driven by a cylinder mechanism 8 in one example. The cylinder mechanism 8 comprises a cylinder 8a and a rod 8b whose protrusion from the cylinder 8a is variable. The grinding tool 5 is fixed to the rod 8b, and the grinding tool 5 can be displaced by changing the protrusion amount of the rod 8b.

[0045] As shown in Figure 6A, the laser welding target area 2i is preferably a protruding portion 2i1 that protrudes in an annular shape from the reference plane P2 connecting the upper portion 2j of area 2i and the lower portion 2k of area 2i before grinding. This grinding is preferably performed in such a way that at least a portion of the protruding portion 2i1 is removed, as shown in Figure 6B. Furthermore, as shown in Figure 6C, it is preferable that the protruding portion 2i1 remains partially after grinding. In this case, the grinding area is prevented from becoming recessed below the reference plane P2, thus suppressing the occurrence of laser welding defects. In the state before grinding, the protruding portion 2i1 has a protrusion height from the reference plane P2 of, for example, 0.10 to 0.50 mm, preferably 0.20 to 0.40 mm. Specifically, these protrusion heights are, for example, 0.10, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45, and 0.50 mm, and may also be within a range of any two of the values ​​exemplified here.

[0046] If the inner container 2 has a parting line in the area 2i to be laser-welded, the protruding shape caused by the parting line makes laser welding defects more likely to occur. However, by removing the protruding shape caused by the parting line through a grinding process, the occurrence of laser welding defects can be suppressed.

[0047] <Laser welding process> In the laser welding process, the inner container 2 and the outer container 3 are laser-welded at the laser welding target area 2i. This forms a joint 3b between the inner container 2 and the outer container 3, creating a sealed space 4 between the inner container 2 and the outer container 3. Laser welding can be performed by irradiating the laser welding target area 2i with the inner container 2 and the outer container 3 while rotating them around the central axis C of the mouth 2a of the inner container 2. It is preferable to perform laser welding with a laser absorbent applied to the laser welding target area 2i. This increases the laser absorption efficiency, enabling efficient laser welding. [Examples]

[0048] The following describes test examples related to the invention from the first perspective.

[0049] 1. Manufacturing of a sample of insulated container 10 <Sample 1> The insulated container 10 of Sample 1 has the structure shown in the above embodiment and has a capacity of 390 mL. The container body 1 of the insulated container 10 is composed of an inner container 2 made of a 1 mm thick hPP resin layer (specifically, from the outside in, hPP layer (70%) / adhesive resin layer (3.5%) / EVOH layer (4%) / adhesive resin layer (3.5%) / hPP layer (19%): the values ​​in parentheses are the layer thickness ratios), and an outer container 3 made of a 1.5 mm thick rPP resin layer (specifically, from the outside in, rPP layer (70%) / adhesive resin layer (3.5%) / EVOH layer (4%) / adhesive resin layer (3.5%) / rPP layer (19%): the values ​​in parentheses are the layer thickness ratios). The sealed space 4 was manufactured by depressurizing to 0.01 atmospheres and then filling with argon gas to 1 atmosphere. The adhesive resin layer was made using a polypropylene-based adhesive resin.

[0050] <Samples 2-6> The insulated container 10 was manufactured in the same manner as Sample 1, except that its configuration was changed as shown in Table 1. In Table 1, hPP-based and rPP-based refer to the hPP-based resin layer and the rPP-based resin layer, respectively.

[0051] 2. Exam The following tests were conducted on samples 1-6 of the insulated container 10.

[0052] <Heat resistance test> In the heat resistance test, the container body 1 of an empty insulated container 10 was left in a 70°C environment for 1 hour, and then it was checked whether the inner container 2 or outer container 3 changed. Containers where neither the inner container 2 nor the outer container 3 deformed were considered OK, while containers where at least one of the inner container 2 or outer container 3 deformed were considered NG. The test results are shown in Table 1.

[0053] In samples 1-3, neither the inner container 2 nor the outer container 3 deformed. In samples 4-5, the inner container 2 deformed. In sample 6, the outer container 3 deformed.

[0054] <Visibility Test> The visibility test involved filling the inner container 2 of the container body 1 of the insulated container 10 with 200 mL of water and checking whether the water level was visible from the outside of the outer container 3. Containers where the water level was clearly visible were considered OK, and those where the water level was unclear were considered NG. The test results are shown in Table 1.

[0055] <Thermal insulation test> The thermal insulation test was conducted by filling an insulated container 10 with 4°C water and leaving it to stand in a 20°C environment for 3 hours, after which the water temperature was measured. After 3 hours of standing, the water temperatures for the PET single-wall container, the polypropylene single-wall container, and the double-wall container (which had the same configuration as Sample 1 except that the gas in the sealed space 4 was air) were 16.3°C, 15.3°C, and 14.1°C, respectively. On the other hand, the water temperatures for Samples 1 and 2 were 12.2°C and 11.2°C, respectively. This result indicates that the insulated containers 10 of Samples 1 and 2 have excellent thermal insulation properties.

[0056] [Table 1] [Explanation of symbols]

[0057] 1: Container body 1a: Mouth 1b: Torso 1c: Bottom 2: Inner container 2a: Mouth 2c: Engagement part 2f: Bottom 2f1 : Groove 2f2: Convex strip 2g: Body 2g1:Shoulder 2g2: Main body 2g4: outer edge 2g5: Reduced diameter part 2g6 : Part 2g7: Reduced diameter part 2g8 : Part 2i: Area to be laser-welded 2i1:Protruding site 2j :part 2k: part 2l: part 3: Outer container 3a: Open end 3b:Joint part 3D: Torso 3d1: Upper torso 3d2: Central Torso 3d3: lower torso 3d4: Stepped section 3d5: Stepped section 3d6: Expanded diameter part 3e: bottom 4: Closed space 5: Grinding Tools 6: Bearing component 7: Head 8: Cylinder mechanism 8a: Cylinder 8b: Rod 10: Insulated container C: Central axis P1: Surface P2: Reference plane α: Inclination angle

Claims

1. An insulated container having a container body, The container body comprises an inner container and an outer container positioned to cover the inner container. A sealed space is provided between the inner container and the outer container. The inner container is made of a resin containing 60% by mass or more of a propylene homopolymer. The outer container is made of a resin containing 60% by mass or more of a random copolymer of propylene and other olefins. The gas in the aforementioned sealed space contains a gas with a lower thermal conductivity than air. An insulated container in which the air pressure in the sealed space is 0.5 to 1.5 atmospheres.

2. An insulating container according to claim 1, An insulated container wherein, at the center of the height of the container body, the wall thickness of the inner container is 0.5 to 1.5 mm, and the wall thickness of the outer container is 1.0 to 2.0 mm.

3. An insulating container according to claim 1 or claim 2, An insulated container in which the total proportion of argon gas, krypton gas, and xenon gas in the sealed space is 50% by volume or more.

Images