JP7543265B2 - Method for manufacturing preforms and method for manufacturing double-walled containers - Google Patents

Description

The present invention relates to a method for manufacturing a preform, a double-walled container, and a method for manufacturing a double-walled container.

Patent Document 1 discloses a two-layer plastic bottle in which the inner layer is made of virgin plastic and the outer layer is made of recycled plastic. Patent Document 2 discloses a method for manufacturing a laminated resin molded product, which includes an outer layer molding step of molding a cylindrical outer layer material from recycled resin, and an inner layer molding step of laminating an inner layer material made of a cylindrical virgin resin that is thinner than the outer layer material on the inner side of the outer layer material.

Japanese Patent Application Publication No. 2002-103429 Japanese Patent Application Publication No. 2002-104362

In recent years, marine pollution caused by plastic waste has come to be seen as a major issue, and efforts to promote the 3Rs of plastics (reuse, reduce, recycle) have been gaining momentum internationally. A method has been developed for food/beverage/pharmaceutical bottles (food containers) in which a preform that has been injection molded with a two-layer structure, inner and outer, is blow molded, with the part that comes into contact with the contents (inner layer) made from virgin material and the part that does not come into contact with the contents (outer layer) made from recycled material.

Among the plastic containers, there are cup-type containers that have insulating properties (insulation properties for keeping things hot and cold). In this type of container, the body is constructed with an inner and outer double wall, and insulating properties are achieved by forming an appropriate space between the inner and outer walls. Although recycled materials should be actively used in such containers as well, no containers that are hygienic when in use and can use recycled materials have been developed at present.

The present invention aims to provide a method for manufacturing a preform that can produce a double-walled container that is hygienic during use even if it uses a large proportion of recycled material, and a method for manufacturing the double-walled container.

One aspect of the present invention that can solve the above problem is
A first step of injecting a recycled material into a first mold to form a primary molded body;
A method for producing a resin preform including the primary molded body and the secondary molded body, comprising: a second step of placing the primary molded body in a second mold and injecting a virgin material to injection mold a secondary molded body;
the primary molded body injection molded in the first step includes an opening, a neck portion connected to the opening, a body portion connected to the neck portion, and a bottom portion connected to the body portion,
The body portion includes a first partial planned portion on the neck portion side, a second partial planned portion on the bottom side, and a third partial planned portion between the first partial planned portion and the second partial planned portion,
a thickness of the second partial planned portion, the third partial planned portion and the bottom portion of the body portion is thinner than a thickness of the first partial planned portion;
This is a method for manufacturing a preform, in which the secondary molded body that is injection molded in the second step is formed on the outside of the second and third partial planned portions and the bottom of the body of the primary molded body.

Another aspect of the present invention that can solve the above problem is
A double-walled container made of resin having an outer wall, an inner wall connected to the outer wall, an inner bottom connected to the inner wall, and an opening provided on the opposite side of the inner bottom across the inner wall,
The opening side portion of the outer wall, the inner wall and the inner bottom have a two-layer structure composed of an inner layer made of recycled material and an outer layer made of virgin material,
A portion of the exterior wall other than the portion on the opening side is made of recycled materials,
The inner wall and the outer layer of the inner bottom are configured to contact contents contained within the double-walled container.

Another aspect of the present invention that can solve the above problem is
a blowing process for stretch-blowing a resin preform including an opening, a neck portion connected to the opening, a body portion connected to the neck portion, and a bottom portion connected to the body portion to form an intermediate molded product;
a pressing step of pressing the intermediate molded product to form a resin double-walled container having an outer wall, an inner wall continuous with the outer wall, an inner bottom continuous with the inner wall, and an opening provided on the opposite side of the inner bottom across the inner wall,
The intermediate molded product has an inner wall corresponding portion corresponding to the inner wall, an outer wall corresponding portion corresponding to the outer wall, and an inner bottom corresponding portion corresponding to the inner bottom,
The inner wall corresponding portion and the inner bottom corresponding portion are formed so as to bulge from the outer wall corresponding portion,
In the pressing step, the inner bottom corresponding portion is pressed so that the inner wall corresponding portion formed to bulge from the outer wall corresponding portion is inverted to the inside of the outer wall corresponding portion, thereby forming the double-walled container;
the body of the preform comprises a first portion on the neck side, a second portion on the bottom side, and a third portion between the first portion and the second portion;
the neck portion and the first portion of the body are constructed from recycled materials;
The method for manufacturing a double-walled container includes manufacturing the second and third portions of the body and the bottom having a two-layer structure having an inner layer made of recycled material and an outer layer made of virgin material.

According to the present invention, it is possible to provide a manufacturing method of a preform capable of forming a double-walled container that is hygienic during use even if a large proportion of recycled material is used, and a manufacturing method of the double-walled container and the double-walled container.

FIG. 2 is a cross-sectional view showing a preform according to an embodiment. FIG. 1 is a cross-sectional view showing a double-walled container according to an embodiment. 4 is a flowchart showing a manufacturing process of a preform according to an embodiment. FIG. 2 is a cross-sectional view showing an injection molding process for a preform according to an embodiment. 4 is a flow chart showing a manufacturing process for a double-walled container according to an embodiment. 3 is a cross-sectional view showing a blow molding process for an intermediate molded product according to an embodiment of the present invention. FIG. 4A to 4C are cross-sectional views showing an embodiment of a pressing step for forming a double-walled container. FIG. 11 is a diagram showing another embodiment of the pressing step. FIG. 11 is a diagram showing another embodiment of the pressing step. FIG. 2 is a diagram showing an apparatus for manufacturing an intermediate molded product or a double-walled container according to an embodiment. 4 is a flowchart showing a manufacturing process of an intermediate molded product or a double-walled container using the manufacturing apparatus according to the embodiment.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the dimensions of each component shown in the drawings may differ from the actual dimensions of each component for the sake of convenience.

First, a preform 10 according to an embodiment will be described with reference to Figure 1. Figure 1 is a cross-sectional view of the preform 10. The preform 10 is a resin molded product having an opening 12, a neck portion 14 connected to the opening 12, a body portion 16 connected to the neck portion 14, and a bottom portion 18 connected to the body portion 16. The body portion 16 of the preform 10 tapers from the neck portion 14 side to the bottom portion 18 side. The body portion 16 has a first portion 16a on the neck portion 14 side, a second portion 16b on the bottom portion 18 side, and a third portion 16c between the first portion 16a and the second portion 16b.

The neck portion 14 and the first portion 16a of the body portion 16 are made of recycled materials prepared by recycling used resin materials. The second portion 16b and the third portion 16c of the body portion 16 and the bottom portion 18 have a two-layer structure consisting of an inner layer 22 made of the above-mentioned recycled material and an outer layer 24 made of virgin material, which is an unused resin material. The first portion 16a and the inner layer 22 in the two-layer structure are continuous and made of the same material. The virgin material and the recycled material are made of synthetic resins such as polypropylene (PP) and polyethylene terephthalate (PET). The preform 10 is used to mold a double-walled container 30, which will be described later.

The weight ratio of the recycled material contained in the preform 10 to the virgin material contained in the preform 10 is 2 or more. Specifically, the weight ratio of the total weight of the first part 16a of the body 16, the second part 16b and the third part 16c of the body 16, and the inner layer 22 in the bottom 18 to the weight of the second part 16b and the third part 16c of the body 16 and the outer layer 24 in the bottom 18 is 2 or more. In addition, although not particularly limited, it is preferable that the ratio of the length of the first part 16a of the body 16 in the direction extending from the neck part 14 to the bottom 18 to the total length of the second part 16b and the third part 16c of the body 16 in the direction extending from the neck part 14 to the bottom 18 is 0.1 or more and less than 1. In addition, it is more preferable that the ratio is 0.3 or more, and particularly preferable that the ratio is 0.5 or more. In addition, it is more preferable that the ratio is 0.9 or less, and particularly preferable that the ratio is 0.8 or less. By being in this numerical range, the ratio of recycled materials used can be further improved, and a double-walled container 30 that is more hygienic during use can be formed. In addition, the thicknesses of the inner layer 22 and the outer layer 24 are approximately uniform in the second portion 16b and the third portion 16c of the body 16 and the bottom 18.

Next, referring to FIG. 2, a double-walled container 30 according to an embodiment will be described. FIG. 2 is a cross-sectional view of the double-walled container 30. The double-walled container 30 is a resin container obtained by blow molding the preform 10. The double-walled container 30 has an outer wall 32, an inner wall 34 connected to the outer wall 32, an inner bottom 36 connected to the inner wall 34, and an opening 38 provided on the opposite side of the inner bottom 36 across the inner wall 34. The outer wall 32 and the inner wall 34 are connected via an edge portion 33 at the end on the opening 38 side. The end of the inner wall 34 opposite the opening 38 is connected via the inner bottom 36. The portion 32a on the opening 38 side of the outer wall 32, the edge portion 33, the inner wall 34, and the inner bottom 36 have a two-layer structure composed of an inner layer (base layer) 42 composed of recycled material and an outer layer (coating layer) 44 composed of virgin material. The recycled material and the virgin material are the same materials as those described in the preform 10. The portion 32b of the outer wall 32 other than the portion 32a on the opening 38 side is made of recycled material. The portion 32b and the inner layer 42 in the two-layer structure are continuous and made of the same material. The third portion 16c of the preform 10 corresponds to the portion 34a on the opening 38 side of the inner wall 34 of the double-walled container 30, the edge portion 33, and the portion 32a on the opening 38 side of the outer wall 32. The outer layer 44 of the inner wall 34 and the inner bottom 36 has a concave shape, and is configured so that the contents, such as a beverage, contained in the double-walled container 30 contacts the outer layer 44 with the concave shape.

In FIG. 2, the distance (diameter) between the inner walls 34 is smaller than the distance (diameter) between the outer walls 32, and the inner walls 34 are disposed inside the outer walls 32. The edge portion 33 has an inner diameter equal to the inner diameter of the inner wall 34 on the opening 38 side, and an outer diameter equal to the outer diameter of the outer wall 32 on the opening 38 side. A space is formed between the inner wall 34 and the outer wall 32. The end of the outer wall 32 opposite the opening 38 on the outer side of the inner wall 34 is open, and the outer bottom 39 of the double-walled container 30 is open. A medium such as air enters the space between the inner wall 34 and the outer wall 32, providing an insulating effect. The double-walled container 30 can be used for purposes such as a coffee cup.

The weight ratio of the recycled material contained in the double-walled container 30 to the virgin material contained in the double-walled container 30 is 2 or more. Specifically, the weight ratio of the total weight of the portion 32b other than the portion 32a on the opening 38 side of the outer wall 32 and the portion 32a on the opening 38 side of the outer wall 32, the edge portion 33, the inner wall 34, and the inner layer 42 on the inner bottom 36 to the weight of the outer layer 44 on the opening 38 side of the outer wall 32, the edge portion 33, the inner wall 34, and the inner bottom 36 is 2 or more. In addition, although not particularly limited, it is preferable that the ratio of the length of the portion 32a on the opening 38 side of the outer wall 32 in the direction extending from the opening 38 to the inner bottom 36 to the length of the portion 32b other than the portion 32a on the opening 38 side of the outer wall 32 in the direction extending from the opening 38 to the inner bottom 36 is greater than 0 and less than 5. In addition, it is more preferable that the ratio is 0.06 or more, and particularly preferably 0.1 or more. Moreover, the ratio is more preferably equal to or less than 3, even more preferably equal to or less than 1, and particularly preferably equal to or less than 0.5. By keeping the ratio within the above range, the ratio of recycled materials used can be further improved, resulting in a double-walled container 30 that is more hygienic during use. The thicknesses of the inner layer 42 and the outer layer 44 are substantially uniform.

Next, a method for manufacturing the preform 10 will be described with reference to Figures 3 and 4. Figure 3 is a flow chart showing the manufacturing process of the preform 10. Figure 4 is a diagram showing the injection molding of the preform 10.

As shown in Figure 3, the manufacturing method of the preform 10 of this embodiment includes a first step S1 and a second step S2, which are two-stage injection molding processes. The first step S1 is a step of injecting recycled material into a first mold to injection mold a primary molded body. The second step S2 is a step of placing the primary molded body in a second mold, injecting virgin material, and injection molding a secondary molded body.

Here, each step will be described with reference to FIG. 4. In the first step S1, the recycled material is injected through the first gate 58 into the cavity formed by the first mold 50, which is composed of the first cavity mold 52, the first injection core mold 54, and the neck mold 56. When the filling of the recycled material into the cavity is completed, the clamping of the first mold 50 is maintained for a predetermined time, and then opened to form the primary molded body 60. In addition, the first cavity mold 52 and the first injection core mold 54 are provided with a circuit (medium circulation hole or medium circulation groove) through which a cooling medium (fluid) for cooling the primary molded body 60 flows, and the cooling medium is appropriately set within a range of, for example, about 5°C to about 20°C.

The primary molded body 60 to be molded includes an opening 62, a neck portion 64 connected to the opening 62, a body portion 66 connected to the neck portion 64, and a bottom portion 68 connected to the body portion 66. The body portion 66 includes a first partial planned portion (first partial forming portion) 66a on the neck portion 64 side, a second partial planned portion (second partial forming portion) 66b on the bottom portion 68 side, and a third partial planned portion (third partial forming portion) 66c between the first partial planned portion 66a and the second partial planned portion 66b. The thicknesses of the second partial planned portion 66b and the third partial planned portion 66c of the body portion 66 and the bottom portion 68 are thinner than the thickness of the first partial planned portion 66a. Furthermore, although not particularly limited, it is preferable that the ratio of the length of the first partial planned portion 66a of the body 66 in the direction extending from the neck portion 64 to the bottom portion 68 to the sum of the lengths of the second partial planned portion 66b and the third partial planned portion 66c of the body 66 in the direction extending from the neck portion 64 to the bottom portion 68 be similar to the length ratio of the first portion 16a of the preform 10 described above to the second portion 16b and the third portion 16c.

The molded primary molded body 60 is raised together with the first injection core mold 54 and the neck mold 56 and separated from the first cavity mold 52. The first injection core mold 54 is further raised and separated from the primary molded body 60. The primary molded body 60 is then rotated together with the neck mold 56 by a rotating means (not shown) while held by the neck mold 56, and is positioned above the second cavity mold 72.

In the second step S2, the neck mold 56 that holds the primary molded body 60 is clamped to the second injection core mold 74 and the second cavity mold 72, so that the primary molded body 60 is accommodated in the second mold 70 that is composed of the second cavity mold 72, the second injection core mold 74, and the neck mold 56. Then, in the cavity formed by the second mold 70, the virgin material is injected through the second gate 78 into the second and third partial planned portions 66b and 66c of the body portion 66 of the primary molded body 60 and the outside of the bottom portion 68. When the filling of the cavity with the virgin material is completed, the clamping of the second mold 70 is maintained for a predetermined time, and then released to mold a preform 10 that includes the primary molded body 60 and the secondary molded body 80 formed outside the second and third partial planned portions 66b and 66c of the body portion 66 and the bottom portion 68.

In this embodiment, the first step S1 of the next preform 10 is performed between the second step S2 of the previous preform 10. In addition, the second cavity mold 72 and the second injection core mold 74 are also provided with a circuit through which a cooling medium flows to cool the secondary molded body 80 and the primary molded body 60, and the cooling medium is appropriately set within a range of, for example, about 5°C to about 20°C. The temperature of the cooling medium, that is, the cooling strength, may be different between the first mold 50 and the second mold 70 (for example, the temperature of the cooling medium of the second mold 70 is set lower than that of the first mold 50). Furthermore, in the second mold 70, the cooling strength may be different between the second cavity mold 72 and the second injection core mold 74 (for example, the temperature of the cooling medium of the second cavity mold 72 is set lower than that of the second injection core mold 55).

In the first step S1 and the second step S2, the primary molded body 60 and the secondary molded body 80 are molded so that the weight ratio of the recycled material contained in the preform 10 to the virgin material contained in the preform 10 is 2 or more. In the second step, the secondary molded body is injection molded so that the thicknesses of the body 16 and the bottom 18 of the preform 10 are uniform. In this embodiment, the thicknesses of the second partial planned portion 66b, the third partial planned portion 66c, and the bottom 68 of the primary molded body are approximately the same as the thickness of the secondary molded body. The ratio of the thickness of these parts (66b, 66c, 68) of the primary molded body to the thickness of the secondary molded body is not particularly limited, but may be, for example, the thickness of these parts (66b, 66c, 68) of the primary molded body: the thickness of the secondary molded body = 1:2 to 5:1, and is particularly preferably set to 1:1 to 3:1. The first partial planned portion 66a, the second partial planned portion 66b, and the third partial planned portion 66c of the primary molded body 60 respectively constitute at least a part of the first portion 16a, the second portion 16b, and the third portion 16c of the preform 10. That is, the third partial planned portion 66c of the primary molded body 60 and the secondary molded body 80 formed outside thereof correspond to the portion on the opening 38 side of the inner wall 34 and the portion 32a on the opening 38 side of the outer wall 32 of the double-walled container 30 molded from the preform 10 (see FIG. 2).

Next, a method for manufacturing the double-walled container 30 will be described with reference to Figures 5 to 7. Figure 5 is a flow chart showing the manufacturing process for the double-walled container 30. Figure 6 is a diagram showing the blow molding of an intermediate molded product, which will be described later. Figure 7 is a diagram showing the pressing process for molding the double-walled container 30. As shown in Figure 5, the manufacturing method for the double-walled container 30 of this embodiment includes a blowing process S3 and a pressing process S4. The blowing process S3 is a process for molding an intermediate molded product by stretch-blowing the preform 10. The pressing process S4 is a process for pressing the intermediate molded product to form the double-walled container 30.

Here, the blowing process S3 will be described with reference to FIG. 6. In the blowing process S3, the preform 10 (not shown) held in the blow neck mold 92 is housed in a blow molding unit 90 including at least a blow cavity mold 94, a blow bottom mold 96, and a stretch rod 98, and the preform 10 is stretched by the stretch rod 98 while being blown with a blow medium to mold an intermediate molded product 100. Note that a pressing rod 96a may be provided in the blow bottom mold. A gas such as air may be used as the blowing medium. A liquid such as water may also be used, or a mixture of a gas and a liquid may also be used.

The intermediate molded product 100 molded in the blow process S3 has an inner wall corresponding portion 104 corresponding to the inner wall 34 of the double-walled container 30, an outer wall corresponding portion 102 corresponding to the outer wall 32 of the double-walled container 30, and an inner bottom corresponding portion 106 corresponding to the inner bottom 36 of the double-walled container 30. The inner bottom corresponding portion 106 is configured to be continuous with the inner wall corresponding portion 104. The inner wall corresponding portion 104 is configured to be continuous with the outer wall corresponding portion 102. The inner wall corresponding portion 104 and the inner bottom corresponding portion 106 are formed to bulge from the outer wall corresponding portion 102.

The part 102a on the inner bottom corresponding part 106 side of the outer wall corresponding part 102, the inner wall corresponding part 104 and the inner bottom corresponding part 106 have a two-layer structure composed of an inner layer 112 composed of recycled material and an outer layer 114 composed of virgin material. The recycled material and the virgin material are the same materials as those described in the preform 10. The part 102b other than the part 102a on the inner bottom corresponding part 106 side of the outer wall corresponding part 102 is composed of recycled material. The part 102b and the inner layer 112 in the two-layer structure are continuous and composed of the same material. The third part 16c of the preform 10 described above corresponds to the part on the outer wall corresponding part 102 side of the inner wall corresponding part 104 of the intermediate molded product 100 and the part 102a on the inner bottom corresponding part 106 side of the outer wall corresponding part 102.

Next, the pressing step S4 will be described with reference to FIG. 7. In the pressing step S4, the inner bottom corresponding part 106 of the intermediate molded product 100 molded in the blowing step S3 is pressed in the blow molding unit 90, and the inner wall corresponding part 104 formed to bulge from the outer wall corresponding part 102 is inverted to the inside of the outer wall corresponding part 102 to mold the double-walled container 30. Specifically, the inner bottom corresponding part 106 is pressed by raising the pressing rod 96a configured to be able to rise and fall provided in the blow bottom mold 96. At this time, the stretch rod 98 may be raised at the same time, or the stretch rod 98 may be raised in advance. In this way, the double-walled container 30 is molded. Note that the pressing step S4 does not have to be performed in the blow molding unit 90. For example, it may be performed in an inversion part or removal part provided downstream of the blow molding part, or it may be performed by another mechanism (device) after the intermediate molded product 100 is removed from the manufacturing device.

8 and 9 are diagrams showing another embodiment of the pressing step S4, which is performed in an inversion section or removal section provided downstream of the blow molding section in the manufacturing apparatus, or in a device (pressing device) separate from the manufacturing apparatus. In the pressing step S4, the intermediate molded product 100 in which the inner wall corresponding portion 104 and the inner bottom corresponding portion 106 are in a softened state and the outer wall corresponding portion 102 is in a solidified state is placed in the containing mold 310 (FIG. 8), the convex pressing mold 330 is moved toward the containing mold 310, the inner bottom corresponding portion 106 is pushed into the containing recess 311 of the containing mold 310, and the inner wall corresponding portion 104 is inverted to the inside of the outer wall corresponding portion 102 (FIG. 9). In addition, before moving the convex pressing die 330 to the housing die 310 side, in a state where the outer wall corresponding part 102 is fitted into the housing recess 311 of the housing die 310, the boundary part between the inner wall corresponding part 104 and the outer wall corresponding part 102 may be held (pressed) in a fixed position by the plane (upper surface) of the housing die 310 located on the opening side of the housing recess 311 and the plane (lower surface) of a ring-shaped die that is movable relative to the housing recess 311. The convex pressing die 330 is a cylindrical die that tapers toward the tip. The convex pressing die 330 is sized so as not to come into contact with the housing recess 311 when moved to the housing recess 311 of the housing die 310. In this method, the outer shape of the convex pressing die 330 is transferred as the outer shape of the inner wall 34 of the double-walled container 30.

Here, an example of a manufacturing apparatus for the intermediate molded product 100 or the double-walled container 30 will be described. The manufacturing apparatus includes a 5- to 6-station manufacturing apparatus (blow molding apparatus) that includes at least a first injection molding section and a second injection molding section for injection molding the preform, a temperature control section for controlling the temperature of the molded preform 10 to a suitable temperature for blowing, a blow molding section for molding the intermediate molded product 100 or the double-walled container 30 by blowing the temperature-controlled preform 10, and a removal section for removing the molded intermediate molded product 100 or the double-walled container 30 (see Japanese Patent Laid-Open Publication No. 55-111236). When the intermediate molded product 100 is removed from the manufacturing apparatus at the removal section, another mechanism (pressing mechanism) is provided downstream of the manufacturing apparatus as a part of the manufacturing apparatus. The configurations of the injection molding section and the blow molding section are the same as those described in the manufacturing method for the preform 10 and the manufacturing method for the double-walled container 30 (FIGS. 4, 6, 7, 8, and 9), respectively. The manufacturing apparatus is a hot parison type resin container manufacturing apparatus, which continuously manufactures the preform 10 and the intermediate molded product 100 or the double-walled container 30.

Figure 10 is a diagram showing an example of a six-station manufacturing apparatus. The six-station manufacturing apparatus 350 shown in Figure 10 includes a first injection molding section 352 that injects recycled material from a first injection device 362 to injection mold a primary molded body, a first temperature adjustment section 354 that adjusts the temperature of the primary molded body formed by the first injection molding section 352, a second injection molding section 353 that injects virgin material from a second injection device 363 outside the primary molded body whose temperature is adjusted by the first temperature adjustment section 354 to injection mold a secondary molded body, a second temperature adjustment section 355 that adjusts the temperature of the molded preform 10 to a suitable temperature for blowing, a blow molding section 356 that blows the temperature-adjusted preform 10 to mold an intermediate molded product 100 or a double-walled container 30, and a removal section 358 for removing the molded intermediate molded product 100 or double-walled container 30. In the manufacturing apparatus 350, the preform 10 and the intermediate molded product 100 or the double-walled container 30 are transported in the direction of the arrow by a transport device 370 composed of a rotating disk or the like. When the intermediate molded product 100 is removed from the manufacturing apparatus 350 at a removal section 358, another mechanism (a pressing mechanism) is provided downstream of the manufacturing apparatus 350 as a part of the manufacturing apparatus.

Figure 11 is a diagram showing the flow of a method for manufacturing an intermediate molded product or a double-walled container when a six-station manufacturing apparatus is adopted. The method for manufacturing an intermediate molded product or a double-walled container implemented by the six-station manufacturing apparatus 350 shown in Figure 10 includes a first injection molding process S31 in which recycled material is injected to injection mold a primary molded body, a first temperature control process S32 in which the temperature of the primary molded body formed in the first injection molding process S31 is controlled, a second injection molding process S33 in which virgin material is injected outside the primary molded body whose temperature is controlled in the first temperature control process S32 to injection mold a secondary molded body, a second temperature control process S34 in which the molded preform 10 is controlled to a temperature suitable for blowing, and a blow molding process S35 in which the intermediate molded product 100 or the double-walled container 30 is molded by blowing the temperature-controlled preform 10. The blow molding process S35 includes at least the blow process described above. The above-mentioned pressing step is preferably performed in the blow molding step S35, but may be performed in an inversion section or removal section provided downstream, or may be performed by a separate mechanism after the intermediate molded product 100 is removed from the manufacturing apparatus 350.

Incidentally, while efforts towards the 3Rs of plastics are gaining momentum internationally, for example, synthetic resin containers for detergents and toners (non-food containers) are often manufactured using flakes obtained by crushing used containers, or blends of recycled pellets and virgin materials. On the other hand, synthetic resin containers for foods, beverages and medicines (food containers) are required to be hygienic, so the use of recycled materials has not progressed much.

Among plastic containers, there are cup-type containers whose body is made of a double wall, with an appropriate space between the inner and outer walls, providing insulation (insulation for keeping things hot or cold). Although recycled materials should be actively used for such containers, no containers that are hygienic when in use and can use recycled materials have been developed to date.

The inventors have intensively studied resin containers that use a large amount of recycled materials while still being hygienic during use. As a result, they have found that by manufacturing a double-walled container using a specific preform, it is possible to form a double-walled container that is hygienic during use even if the proportion of recycled materials used is large. That is, according to the above preform 10, in which the neck portion 14 and the first portion 16a of the body portion 16 are made of recycled materials, and the second portion 16b and the third portion 16c of the body portion 16 and the bottom portion 18 have a two-layer structure consisting of an inner layer 22 made of recycled materials and an outer layer 24 made of virgin material, the inner wall 34 and the inner bottom 36 of the molded double-walled container 30, including the container inner surface and a part of the container outer surface of the outer wall 32 that comes into contact with the user's lips, can be made of virgin material, and the container can be made hygienic and can use a high proportion of recycled materials.

In addition, in the above preform 10, the neck portion 14 and the first portion 16a of the body portion 16 are made from recycled materials, and the second portion 16b and the third portion 16c of the body portion 16 and a portion of the bottom portion 18 are also made from recycled materials, so that the recycled material can be used in a weight ratio of 2 or more to the virgin material, and a high proportion of recycled material can be used.

In the above-mentioned manufacturing method of the preform 10, in the first step S1, a primary molded body 60 having a thickness of the second and third partial planned portions 66b and 66c of the body 66 and the bottom 68 thinner than the thickness of the first partial planned portion 66a of the body 66 is injection molded, and in the second step S2, a secondary molded body 80 is formed on the outside of the second and third partial planned portions 66b and 66c of the body 66 of the primary molded body 60 and the bottom 68 to form the preform 10. In the preform 10 manufactured by this manufacturing method, as described above, the inner surface of the inner wall 34 and the inner bottom 36 of the molded double-walled container 30 and the outer surface of a part of the outer wall 32 that comes into contact with the user's lips can be made of virgin material, and the container can be made hygienic and can use a high proportion of recycled material.

In addition, in the above-mentioned manufacturing method of the preform 10, the secondary molded body 80 is injection molded so that the thickness of the body 16 and bottom 18 of the preform 10 is uniform, thereby providing a preform 10 that can be used to form a double-walled container 30 with high productivity.

In addition, the above-mentioned double-walled container 30 has a two-layer structure in which the portion 32a on the opening 38 side of the outer wall 32, the inner wall 34 and the inner bottom 36 are made of an inner layer 42 made of recycled material and an outer layer 44 made of virgin material, and the portion 32b of the outer wall 32 other than the portion 32a on the opening 38 side is made of recycled material, so that the portions including the inner container surfaces of the inner wall 34 and inner bottom 36 of the double-walled container 30 and the portion of the outer container surface of the part of the outer wall 32 that comes into contact with the user's lips can be made of virgin material, making the container hygienic and enabling the use of a high proportion of recycled material.

The present invention is not limited to the above-described embodiments, and can be modified, improved, etc. as appropriate. In addition, the material, shape, dimensions, values, form, number, location, etc. of each component in the above-described embodiments are arbitrary and not limited as long as they can achieve the present invention.

For example, in the above embodiment, the virgin material and the recycled material are described as having PP resin as the base material, but the material is not limited to this. However, it is preferable to use a synthetic resin material with excellent heat resistance. Note that the recycled material and the virgin material may each be made of a different base resin material, as long as the material has excellent heat resistance.

For example, the edge 33 of the double-walled container 30 in the above embodiment has been described as having an inner diameter equal to the inner diameter of the inner wall 34 on the opening 38 side, and an outer diameter equal to the outer diameter of the outer wall 32 on the opening 38 side, but the present invention is not limited to this. For example, the edge may be a flange-shaped edge having an outer diameter larger than the outer diameter of the outer wall 32 on the opening 38 side.

In the above embodiment, the blowing process S3 and the pressing process S4 are performed in the same blow molding unit 90, but the present invention is not limited to this embodiment. The blowing process S3 may be performed in one molding unit to mold the intermediate molded product 100, and the intermediate molded product 100 may be moved to another molding unit to perform the pressing process S4. In this case, the temperature of the intermediate molded product 100 is adjusted as necessary so that the intermediate molded product 100 can be pressed and reversed in the pressing process S4. Note that performing the blowing process S3 and the pressing process S4 in the same blow molding unit 90 is preferable because it reduces the number of steps.

Although a 5-6 station type manufacturing apparatus for the double-walled container 30 has been described in the above embodiment, the present invention is not limited to this form. The manufacturing apparatus may be configured with a blow molding section that molds the double-walled container 30 from the preforms 10 manufactured by a separate manufacturing apparatus. The manufacturing apparatus may also include at least an injection molding section and a blow molding section.

Below, aspects extracted from the above-described embodiment and its modifications will be listed.
[1]
A resin preform including an opening, a neck portion connected to the opening, a body portion connected to the neck portion, and a bottom portion connected to the body portion,
the body portion includes a first portion on the neck side, a second portion on the bottom side, and a third portion between the first portion and the second portion;
the neck portion and the first portion of the body are constructed from recycled materials;
A preform, wherein the second and third portions of the body and the bottom have a two-layer structure consisting of an inner layer made of recycled material and an outer layer made of virgin material.
[2]
The preform according to [1], wherein the weight ratio of the recycled material contained in the preform to the virgin material contained in the preform is 2 or more.
[3]
A preform for molding a double-walled container having an outer wall, an inner wall continuous with the outer wall, and an inner bottom continuous with the inner wall, wherein the third portion corresponds to at least a part of the inner wall and at least a part of the outer wall of the double-walled container. The preform according to [1] or [2].
[4]
A first step of injecting a recycled material into a first mold to form a primary molded body;
A method for producing a resin preform including the primary molded body and the secondary molded body, comprising: a second step of housing the primary molded body in a second mold and injecting a virgin material to injection mold a secondary molded body,
the primary molded body injection molded in the first step includes an opening, a neck portion connected to the opening, a body portion connected to the neck portion, and a bottom portion connected to the body portion,
The body portion includes a first partial planned portion on the neck portion side, a second partial planned portion on the bottom side, and a third partial planned portion between the first partial planned portion and the second partial planned portion,
a thickness of the second partial planned portion, the third partial planned portion and the bottom portion of the body portion is thinner than a thickness of the first partial planned portion;
a secondary molded body to be injection molded in the second step being formed on the outside of the second partial planned portion and the third partial planned portion of the body and the bottom of the primary molded body.
[5]
The method for manufacturing a preform according to [4], wherein a weight ratio of the recycled material injected in the first step to the virgin material injected in the second step is 2 or more.
[6]
The method for producing a preform according to [4] or [5], wherein in the second step, the secondary molded body is injection molded so that the thickness of the body and bottom of the preform is uniform.
[7]
A method for manufacturing a preform for molding a double-walled container having an outer wall, an inner wall connected to the outer wall, and an inner bottom connected to the inner wall, wherein the third partial intended portion of the primary molded body and the secondary molded body formed outside thereof correspond to at least a part of the inner wall and at least a part of the outer wall of the double-walled container. The method for manufacturing a preform described in any one of [4] to [6].
[8]
A double-walled resin container having an outer wall, an inner wall continuous with the outer wall, an inner bottom continuous with the inner wall, and an opening provided on the opposite side of the inner bottom across the inner wall,
The opening side portion of the outer wall, the inner wall and the inner bottom have a two-layer structure composed of an inner layer made of recycled material and an outer layer made of virgin material,
A portion of the exterior wall other than the portion on the opening side is made of recycled materials,
A double-walled container, wherein the inner wall and the outer layer of the inner bottom are configured to contact contents contained within the double-walled container.
[9]
9. The double-walled container according to claim 8, wherein the weight ratio of recycled material contained in the double-walled container to virgin material contained in the double-walled container is 2 or more.
[10]
a blowing process for stretch-blowing a resin preform including an opening, a neck portion connected to the opening, a body portion connected to the neck portion, and a bottom portion connected to the body portion to form an intermediate molded product;
a pressing step of pressing the intermediate molded product to form a resin double-walled container having an outer wall, an inner wall continuous with the outer wall, an inner bottom continuous with the inner wall, and an opening provided on the opposite side of the inner bottom across the inner wall,
The intermediate molded product has an inner wall corresponding portion corresponding to the inner wall, an outer wall corresponding portion corresponding to the outer wall, and an inner bottom corresponding portion corresponding to the inner bottom,
The inner wall corresponding portion and the inner bottom corresponding portion are formed so as to bulge from the outer wall corresponding portion,
In the pressing step, the inner bottom corresponding portion is pressed so that the inner wall corresponding portion formed to bulge from the outer wall corresponding portion is inverted to the inside of the outer wall corresponding portion, thereby forming the double-walled container;
the body of the preform comprises a first portion on the neck side, a second portion on the bottom side, and a third portion between the first portion and the second portion;
the neck portion and the first portion of the body are constructed from recycled materials;
A method for manufacturing a double-walled container, wherein the second and third portions of the body and the bottom have a two-layer structure consisting of an inner layer made of recycled material and an outer layer made of virgin material.
[11]
The method for manufacturing a double-walled container according to claim 10, wherein the third portion corresponds to at least a portion of the inner wall and at least a portion of the outer wall of the double-walled container.

Although the present invention has been described in detail with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention.
This application is based on a Japanese patent application (Patent Application No. 2019-121122) filed on June 28, 2019, the entirety of which is incorporated by reference. In addition, all references cited herein are incorporated in their entirety.

10: preform, 12: opening, 14: neck portion, 16: body portion, 16a: first portion, 16b: second portion, 16c: third portion, 18: bottom portion, 22: inner layer, 24: outer layer, 30: double-walled container, 32: outer wall, 34: inner wall, 36: inner bottom, 38: opening, 42: inner layer, 44: outer layer, 50: first mold, 52: first cavity mold, 54: first injection core mold, 56: neck mold, 58: first gate, 60: primary molded body, 70: second mold, 72: second cavity mold, 74: second injection core mold, 78: second gate, 80: secondary molded body, 90: blow molding unit, 100: intermediate molded product

Claims (4)

A first step of injecting a recycled material into a first mold to form a primary molded body;
A method for producing a resin preform including the primary molded body and the secondary molded body, comprising: a second step of placing the primary molded body in a second mold and injecting a virgin material to injection mold a secondary molded body;
The primary molded body that is injection molded in the first step includes an opening, a neck portion that is continuous with the opening, a body portion that is continuous with the neck portion, and a bottom portion that is continuous with the body portion,
The body portion includes a first partial planned portion on the neck portion side, a second partial planned portion on the bottom side, and a third partial planned portion between the first partial planned portion and the second partial planned portion,
a thickness of the second partial planned portion, the third partial planned portion and the bottom portion of the body portion is thinner than a thickness of the first partial planned portion,
a secondary molded body injection-molded in the second step being formed on the outside of the second partial planned portion and the third partial planned portion of the body and the bottom of the primary molded body. The method for manufacturing a preform according to claim 1, wherein the weight ratio of the recycled material injected in the first step to the virgin material injected in the second step is 2 or more. A method for manufacturing a preform for molding a double-walled container having an outer wall, an inner wall connected to the outer wall, and an inner bottom connected to the inner wall, the method being as described in claim 1 or 2, in which the third planned portion of the primary molded body and the secondary molded body formed outside thereof correspond to at least a part of the inner wall and at least a part of the outer wall of the double-walled container. a blowing process for stretch-blowing a resin preform including an opening, a neck portion connected to the opening, a body portion connected to the neck portion, and a bottom portion connected to the body portion to form an intermediate molded product;
a pressing step of pressing the intermediate molded product to form a resin double-walled container having an outer wall, an inner wall continuous with the outer wall, an inner bottom continuous with the inner wall, and an opening provided on the opposite side of the inner bottom across the inner wall,
The intermediate molded product has an inner wall corresponding portion corresponding to the inner wall, an outer wall corresponding portion corresponding to the outer wall, and an inner bottom corresponding portion corresponding to the inner bottom,
The inner wall corresponding portion and the inner bottom corresponding portion are formed so as to bulge from the outer wall corresponding portion,
In the pressing step, the inner bottom corresponding portion is pressed so that the inner wall corresponding portion formed to bulge from the outer wall corresponding portion is inverted to the inside of the outer wall corresponding portion, thereby forming the double-walled container;
the body of the preform comprises a first portion on the neck side, a second portion on the bottom side, and a third portion between the first portion and the second portion;
the neck portion and the first portion of the body are constructed from recycled materials;
A method for manufacturing a double-walled container, wherein the second and third portions of the body and the bottom have a two-layer structure consisting of an inner layer made of recycled material and an outer layer made of virgin material.

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