Sheet for forming container, food container, and food container constituent member

Abstract

To provide a sheet for forming a container, which has excellent cold resistance and can reduce an environmental load, and to provide a food container and a food container constituent member.SOLUTION: A container-forming sheet 10-1 has a laminated structure formed by laminating at least an outer layer 11, an intermediate layer 12, and an inner layer 13. The intermediate layer contains recycled polyethylene terephthalate, and isophthalic acid. The outer layer and the inner layer contain cyclohexanedimethanol and / or isophthalic acid. The total mass of the outer layer and the inner layer is 2 mass% or more and 80 mass% or less with respect to the whole sheet.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a container-forming sheet, a food container, and a food container-constituting member. [Background technology]

[0002] In recent years, there has been an increasing number of occasions where cold-resistant containers for storing low-temperature foods (e.g., frozen foods, frozen desserts, ice, etc.) are used in a manner that puts them in direct contact with consumers' hands and mouths. Therefore, there is a demand for containers that are not only cold-resistant but also have the performance to function as food containers. For example, a service is available at convenience stores and other stores where customers can purchase a cup filled with ice and pour a beverage directly into the cup from a drink server or the like, thereby providing a freshly brewed beverage on the spot. Therefore, there is a demand for cold-resistant food containers that have been used for storing and transporting low-temperature foods to not only be cold-resistant and shock-resistant, but also to be endowed with hygienic surfaces that come into contact with food, and to be endowed with a top seal that enables the container to be airtight.

[0003] Furthermore, in recent years, recycled polyethylene terephthalate (hereinafter referred to as "recycled PET") that has undergone a recycling process has been widely used for food containers (including, for example, the container body and lid) in order to reduce the environmental impact and cut costs. When recycled PET is used for food containers, sufficient consideration must be given to safety so that chemical contaminants and foreign substances that are mixed in the recycled PET do not remain in the food container and migrate into the food, causing health hazards to consumers, and food containers that cause health hazards to consumers are not distributed.

[0004] For example, Patent Document 1 proposes a technology in which an intermediate layer made of a mixture of polyamide and polyester is placed between layers made of polyester, and the relationship between the polyamide content of the intermediate layer and the thickness of the intermediate layer in the total thickness is specified to ensure sufficient adhesion between the polyester layer and the intermediate layer. This technology eliminates the need for adhesive resin, and even if resin scrap, which was previously discarded during the production of multilayer containers, is crushed and mixed into the intermediate layer as recycled material, the container still has practical transparency, and furthermore, the layer containing the recycled material does not come into direct contact with the stored items, making it possible to achieve excellent safety. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-297344 Summary of the Invention [Problem to be solved by the invention]

[0006] For the cold-resistant containers, it is necessary to use an amorphous resin to provide excellent cold resistance and top sealing properties, but because the resin is amorphous, it has been difficult to recycle it together with polyethylene terephthalate, which is crystalline.

[0007] Therefore, a primary object of the present invention is to provide a container-forming sheet, a food container, and a food container component that have excellent cold resistance and can reduce the environmental impact. [Means for solving the problem]

[0008] The present invention provides at least It has a laminated structure in which an outer layer, an intermediate layer, and an inner layer are laminated, the intermediate layer comprises recycled polyethylene terephthalate and isophthalic acid; the outer layer and the inner layer contain cyclohexanedimethanol and / or isophthalic acid; The total mass of the outer layer and the inner layer is 2% by mass or more and 80% by mass or less with respect to the entire sheet. A container forming sheet is provided. The outer layer and the inner layer may be composed of cyclohexanedimethanol only. Furthermore, the outer layer and the inner layer may not contain cyclohexanedimethanol. The intermediate layer may also contain cyclohexanedimethanol, The total mass of isophthalic acid contained in the intermediate layer when the intermediate layer does not contain cyclohexanedimethanol, or the total mass of cyclohexanedimethanol and isophthalic acid contained in the intermediate layer when the intermediate layer contains cyclohexanedimethanol, may be 1% by mass or more and 97% by mass or less with respect to the entire sheet. The intermediate layer may contain scraps and / or waste materials of the container-forming sheet. The recycled polyethylene terephthalate contained in the intermediate layer may be recycled polyethylene terephthalate obtained by recycling scraps and / or waste materials generated during the molding of polyethylene terephthalate containers. The polyethylene terephthalate container is a PET bottle, The scraps and / or waste materials may be those generated during the molding of the PET bottle preform. The polyethylene terephthalate contained in the intermediate layer may be entirely recycled polyethylene terephthalate. The present invention also provides a food container and a food container component formed from the container-forming sheet. The food container and food container components may be cold-resistant at a storage temperature of at least -35°C. [Effects of the Invention]

[0009] The present invention can provide a container-forming sheet, a food container, and a food container-constituting member that have excellent cold resistance and can reduce the environmental load. The effects of the present invention are not necessarily limited to those described herein. This may be any of the effects described in the specification. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a cross-sectional view of a container-forming sheet according to a first embodiment of the present invention. [Figure 2] 1 is a cross-sectional view showing an example of the configuration of an extruder, a cooling device, and a carrying-out device used in the production of a container-forming sheet. [Figure 3] FIG. 10 is a perspective view of a food container and food container components according to a third embodiment of the present invention. [Figure 4] FIG. 10 is a perspective view of a food container according to a fourth embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] [Term definition] In this specification, polyethylene terephthalate may be referred to simply as PET. Furthermore, within polyethylene terephthalate (hereinafter referred to as PET), PET newly synthesized from raw materials may be referred to as virgin PET, and PET produced from used PET containers (e.g., PET bottles) may be referred to as recycled PET.

[0012] Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The embodiments described below are representative of the present invention and should not be construed as narrowing the scope of the present invention. Even when the present specification describes that the container-forming sheet, food container, and food-container-constituting member according to the present invention each have multiple effects, it is sufficient that the container-forming sheet, food container, and food-container-constituting member according to the present invention each have at least one effect. The effects described in the present invention are merely examples and are not intended to be limiting, and other effects may also be achieved.

[0013] This technology will be described in the following order. 1. Container-forming sheet according to the first embodiment (1) Structure of the container forming sheet (2) Explanation of each component (3) Manufacturing method of container forming sheet 2. Container-forming sheet according to the second embodiment 3. Use of the container forming sheet according to the embodiment of the present invention 4. Food container and food container component according to the third embodiment (1) Food container composition (2) Food container manufacturing method (3) Physical properties 5. Food container according to the fourth embodiment

[0014] 1. Container-forming sheet according to the first embodiment The container-forming sheet according to the first embodiment of the present invention is a sheet used for forming food containers (e.g., food container bodies, beverage container bodies and their lids, etc.). The sheet has a laminated structure in which at least an outer layer, an intermediate layer, and an inner layer are laminated, the intermediate layer containing recycled PET and isophthalic acid, the outer layer and the inner layer containing cyclohexanedimethanol and isophthalic acid, and the total mass of the outer layer and the inner layer is 2% by mass or more and 80% by mass or less of the entire sheet.

[0015] (1) Structure of the container forming sheet Fig. 1 is a cross-sectional view of a container-forming sheet 10-1 according to a first embodiment of the present invention. The container-forming sheet 10-1 has a laminated structure (three-layer structure) in which an outer layer 11, an intermediate layer 12, and an inner layer 13 are laminated. In a food container or food-container component formed from the container-forming sheet 10-1, the inner layer 13 is a layer having a surface that comes into contact with food or the like, and the outer layer 11 is a layer located on the other surface of the inner layer 13 in the stacking direction and having a surface that comes into contact with a person's fingers. The intermediate layer 12 is a layer located between the inner layer 13 and the outer layer 11.

[0016] (2) Explanation of each component [Outer layer 11 and inner layer 13] The outer layer 11 and the inner layer 13 contain cyclohexanedimethanol and / or isophthalic acid. Furthermore, as long as they contain cyclohexanedimethanol and / or isophthalic acid, the outer layer 11 and the inner layer may have the same or different compositions. Due to the inclusion of cyclohexanedimethanol and isophthalic acid, which have excellent cold resistance, in the outer layer 11 and the inner layer 13, the container forming sheet 10-1 of the present invention has excellent cold resistance. Furthermore, when a lid made of a top seal material is used, the inner layer, including the heat-sealed surface of the lid, contains amorphous cyclohexanedimethanol, thereby providing excellent top sealability. Furthermore, the outer layer 11 and the inner layer 13 are laminated to cover the intermediate layer 12, which contains recycled PET. This configuration prevents the recycled PET from coming into contact with human hands and contents such as food, thereby reducing environmental impact and improving the hygiene of the container forming sheet.

[0017] (cyclohexanedimethanol) In this embodiment, cyclohexanedimethanol is a component that imparts cold resistance to a container formed from the container-forming sheet according to the present invention. Furthermore, since it is amorphous, it is a component that is added to impart top-sealing properties.

[0018] In the present invention, cyclohexanedimethanol may be substituted for a part of another polymer or may be contained as a copolymer of another polymer. For example, cyclohexanedimethanol may be contained in a form in which cyclohexanedimethanol substitutes for the glycol component of a polyoxyalkylene glycol such as polyethylene glycol or polypropylene glycol. Alternatively, cyclohexanedimethanol may be contained as a copolymer of a polyester resin and a polyoxyalkylene glycol in which the glycol component is substituted with cyclohexanedimethanol.

[0019] (Isophthalic acid) In this embodiment, isophthalic acid is a component that imparts cold resistance to containers formed from the container-forming sheet according to the present invention. It is also compatible with amorphous cyclohexanedimethanol and functions as a crystallization inhibitor for cyclohexanedimethanol. Since isophthalic acid itself crystallizes when treated at high temperatures, it can be recycled together with PET, which is also crystalline.

[0020] In the present invention, isophthalic acid may be substituted for a part of another polymer or may be contained as a copolymer of another polymer. For example, isophthalic acid may be contained in a form in which isophthalic acid is substituted for the glycol component of a polyoxyalkylene glycol such as polyethylene glycol or polypropylene glycol. Alternatively, isophthalic acid may be contained as a copolymer of a polyester resin and a polyoxyalkylene glycol in which the glycol component is substituted with isophthalic acid.

[0021] The total mass of the outer layer 11 and the inner layer 13 is preferably 2% by mass or more, more preferably 5% by mass or more, and even more preferably 30% by mass or more, of the entire container-forming sheet 10-1. The total mass of the outer layer 11 and the inner layer 13 is preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 60% by mass or less, of the entire container-forming sheet 10-1. The outer layer 11 and the inner layer 13 may have the same mass or different masses.

[0022] [Middle layer 12] The intermediate layer 12 contains recycled PET and isophthalic acid. The PET contained in the intermediate layer 12 may contain only recycled PET, or may contain recycled PET and virgin PET. Because the intermediate layer 12 contains recycled PET, carbon dioxide emissions can be significantly reduced compared to when virgin PET is used, thereby reducing the environmental impact and reducing costs. Furthermore, because the intermediate layer 12 contains isophthalic acid, the cold resistance of the intermediate layer 12 is improved.

[0023] (Recycled PET) In this embodiment, recycled PET is used instead of virgin PET as the resin for constituting the intermediate layer of the container-forming sheet according to the present invention, the food container, and the food container constituent members. The recycled PET is PET that can be recycled from used PET food containers (e.g., PET bottles) and reused. Recycling methods for obtaining the recycled PET used in this embodiment mainly include chemical recycling (chemical recycling method) and mechanical recycling (physical recycling method). Mechanical recycling is a recycling method in which collected PET is sorted, crushed, and washed to thoroughly remove surface dirt and foreign matter, and then exposed to high temperatures to diffuse contaminants remaining inside the resin, decontaminating it and allowing it to be reused. Chemical recycling is a recycling method in which collected PET is sorted, crushed, and washed to remove foreign matter, and then depolymerized to break it down into raw materials or intermediate materials for PET resin, which are then purified and reused as new polymerized PET.

[0024] In a preferred embodiment of the present invention, the recycled PET may be recycled from, for example, used PET containers (e.g., PET bottles) or scraps and / or waste generated during the manufacturing process of PET containers. The scraps and / or waste of the present invention may be, for example, scraps and / or waste generated during the molding of PET bottle container preforms (semi-finished products before blow molding). When the PET bottle preforms are molded by injection molding, the scraps may be, for example, scraps generated from the runners, spools, gates, etc. of the mold when resin is injected into the mold. When the PET bottle preforms are molded by compression molding, the scraps may be, for example, flash generated from excess resin overflowing from the parting surface when resin is poured into the female mold and the male mold is closed. Furthermore, the waste may be, for example, defectively molded PET containers (e.g., PET bottles) (e.g., products that fail inspection). The scraps and / or waste generated during the molding of PET bottle container preforms (semi-finished products before blow molding) are not sold on the market and therefore are relatively free of contamination and foreign matter.

[0025] In a preferred embodiment of the present invention, the intermediate layer 12 may contain cyclohexanedimethanol, which further improves the cold resistance of the intermediate layer 12.

[0026] When the intermediate layer 12 does not contain cyclohexanedimethanol, the total mass of isophthalic acid contained in the intermediate layer 12 is preferably 1% by mass or more, more preferably 3% by mass or more, and even more preferably 5% by mass or more, based on the entire container-forming sheet 10-1. Furthermore, the total mass of isophthalic acid contained in the intermediate layer 12 is preferably 97% by mass or less, more preferably 95% by mass or less, and even more preferably 85% by mass or less, based on the entire container-forming sheet 10-1. This configuration provides excellent cold resistance and reduces environmental impact.

[0027] When the intermediate layer 12 contains cyclohexanedimethanol, the total mass of the cyclohexanedimethanol and isophthalic acid contained in the intermediate layer 12 is preferably 1% by mass or more, more preferably 3% by mass or more, and even more preferably 5% by mass or more, based on the entire container-forming sheet 10-1. Furthermore, the total mass of the cyclohexanedimethanol and isophthalic acid contained in the intermediate layer 12 is preferably 97% by mass or less, more preferably 95% by mass or less, and even more preferably 85% by mass or less, based on the entire container-forming sheet 10-1. This configuration provides excellent cold resistance and reduces environmental impact.

[0028] In a preferred embodiment of the present invention, the intermediate layer 12 may contain scrap and / or waste material from the container-forming sheet 10-1. This configuration enables the container-forming sheet according to this embodiment and containers formed from the container-forming sheet to be recycled, thereby reducing the environmental impact. In particular, in conventional technologies, cyclohexanedimethanol is amorphous, making it difficult to recycle crystalline PET. In contrast, the present invention proposes a new recycling method targeting cold-resistant containers containing cyclohexanedimethanol that were difficult to recycle using conventional technologies and therefore discarded.

[0029] Furthermore, as the number of times the intermediate layer 12 is recycled by utilizing scraps and / or waste materials from the container-forming sheet 10-1 increases, the content of cyclohexanedimethanol in the intermediate layer 12 increases, further improving the cold resistance of the container-forming sheet 10-1. This has an advantage different from the conventional technology in that, while the quality of recycled materials gradually deteriorates with repeated recycling, repeated recycling makes it possible to achieve cold resistance equal to or greater than that of virgin materials.

[0030] The mass of the intermediate layer 12 is preferably 20% by mass or more, more preferably 30% by mass or more, and even more preferably 40% by mass or more, based on the entire container-forming sheet 10-1. The mass of the intermediate layer 12 is preferably 98% by mass or less, more preferably 95% by mass or less, and even more preferably 70% by mass or less, based on the entire container-forming sheet 10-1.

[0031] (3) Manufacturing method of container forming sheet An example of a method for manufacturing a container-forming sheet according to the first embodiment will be described below with reference to Fig. 2. Fig. 2 is a cross-sectional view showing an example of the configuration of an extruder, a cooling device, and a carrying-out device involved in the manufacture of a container-forming sheet.

[0032] First, materials for the container-forming sheet 10-1 are introduced into an extruder 100. The extruder 100 performs a co-extrusion multilayer T-die process, which is a method for simultaneously extruding multiple different materials. For example, the extruder 100 includes three cylinders 110 and a T-die 120. Specifically, the materials for the outer layer 11, the intermediate layer 12, and the inner layer 13 are introduced into the three cylinders 110 through inlets 130. Cyclohexanedimethanol and isophthalic acid are introduced as the materials for the outer layer 11 and the inner layer 13, and recycled PET, isophthalic acid, cyclohexanedimethanol, and, if necessary, scrap and / or waste material from the container-forming sheet 10-1 are introduced as the materials for the intermediate layer 12. The materials introduced into each cylinder 110 are kneaded while being conveyed by a heated, rotating screw 140, and then join near the discharge outlet 120a of the T-die 120 and are extruded together through the discharge outlet 120a. The container forming sheet 10-1 extruded from the extrusion molding machine 100 is cooled while being conveyed in a straight state by the cooling device 200, and then conveyed out by the conveying device 300.

[0033] 2. Container-forming sheet according to the second embodiment The container-forming sheet according to the second embodiment of the present invention is a sheet used for forming food containers (e.g., food container bodies, beverage container bodies and their lids, etc.). The sheet has a laminated structure in which at least an outer layer, an intermediate layer, and an inner layer are laminated, and the intermediate layer contains recycled PET and isophthalic acid, and the outer layer and the inner layer contain isophthalic acid. Furthermore, none of the outer layer, the intermediate layer, or the inner layer contains cyclohexanedimethanol. The total mass of the outer layer and the inner layer is 2% by mass or more and 80% by mass or less of the entire sheet.

[0034] The container-forming sheet 10-2 according to the second embodiment of the present invention is similar to the container-forming sheet 10-1 according to the first embodiment, except that cyclohexanedimethanol is not contained in any of the outer layer 11, intermediate layer 12, and inner layer 13. Therefore, the explanations given above in 1. (1) Structure of the container-forming sheet, (2) Explanation of each component, and (3) Manufacturing method of the container-forming sheet for the container-forming sheet 10-1 according to the first embodiment also apply to the container-forming sheet 10-2 according to the second embodiment. Therefore, explanations of the structure, each component, and manufacturing method of the sheet according to the second embodiment will be omitted.

[0035] The container-forming sheet according to the second embodiment of the present invention has excellent cold resistance because the outer layer, the intermediate layer, and the inner layer each contain isophthalic acid. Furthermore, although isophthalic acid is a crystallization inhibitor, the sheet itself is crystalline, allowing it to be used in conventional PET recycling. Therefore, the container-forming sheet according to the second embodiment of the present invention has excellent cold resistance and can reduce environmental impact.

[0036] 3. Use of the container forming sheet according to the embodiment of the present invention The components of each layer of the container-forming sheet according to the embodiment of the present invention may be appropriately selected depending on the recycling method. For example, when only the container-forming sheet according to the present invention and food containers formed from the sheet are recycled, the container-forming sheet according to the first embodiment may be selected. Furthermore, when the container-forming sheet and food containers formed from the sheet are recycled together with general PET, the container-forming sheet according to the second embodiment may be selected. In this way, the present invention can be configured to be suitable for various recycling methods.

[0037] 4. Food container and food container component according to the third embodiment The food container according to the third embodiment of the present invention is a food container formed from the container forming sheet according to the present invention and is composed of food container components (e.g., the container body of a food container, the body of a beverage container and their lids, etc.).

[0038] The food container according to the third embodiment may be a food container comprising, for example, a food container body and a food container component that serves as a lid for the food container. The food container body is formed from the container forming sheet according to the present invention and includes, for example, a bottom portion, side portions extending upward from the periphery of the bottom portion, and an opening surrounded by the upper end of the side portions. The food container body may also include a flange portion formed at the opening that extends from the inside of the container to the outside. The lid is formed from the container forming sheet according to the present invention and includes, for example, a mating portion that mates with the opening of the food container body and a ceiling portion that covers the opening. The lid may be mated with the flange portion of the opening of the food container body to close the opening of the food container body.

[0039] The shapes of the bottom and the opening of the container body may be, for example, circular, elliptical, polygonal, or substantially polygonal, but are not limited thereto and may be appropriately selected depending on the purpose. The shapes of the bottom and the opening may be the same or different.

[0040] In the lid, the shape of the fitting portion may be, for example, but not limited to, a circle, an ellipse, a polygon, or a substantially polygonal shape, and may be appropriately selected depending on the shape of the container. In addition, the ceiling portion may be flat or may protrude in a dome shape to fit the contents, but is not limited to these.

[0041] (1) Container configuration FIG. 3 is a perspective view of a food container and food container components according to a third embodiment of the present invention. As shown in FIG. 3, the food container 30 is composed of a container body 31 and a lid 32. The container body 31 is a container body formed, for example, from the container forming sheet according to the first embodiment of the present invention. As shown in FIG. 3, the container body 31 has a bottom surface portion 33, a container body side surface portion 34, and a flange portion 35 extending outward from the outer edge of the opening of the container body. The lid 32 has a mating portion 36 and a ceiling portion 37. The flange portion 35 of the container body 31 and the mating portion of the lid 32 are mated to close the opening of the container body 31.

[0042] In the food container 30 of the third embodiment of the present invention, in the container forming sheet 10-1 of the first embodiment, the outer layer 11 can be the inner layer of the container body 31 (the layer having the food contact surface and the top seal fused surface of the flange portion 35), and the inner layer 13 can be the outer layer of the container body 31 (the layer having the surface that comes into contact with human fingers).

[0043] The food container and food container component according to the third embodiment of the present invention are formed from the container forming sheet according to the first embodiment, and therefore have excellent cold resistance and can reduce the environmental impact.

[0044] (2) Food container manufacturing method [Food container and food container component molding process] As described above, the food container 30 and food container components (container body 31 and lid 32) are formed, for example, by sheet forming (e.g., vacuum forming, pressure forming, press forming, etc.) the container-forming sheet 10-1. By this sheet forming, multiple food container components are simultaneously formed in a continuous, integrated manner on the container-forming sheet 10-1.

[0045] A brief description will now be given of a method for manufacturing the food container 30 and the food container components (container body 31 and lid 32). As described above, the container forming sheet 10-1 extruded from the extrusion molding machine 100 is transported through the cooling device 200 and then carried out from the carrying-out device 300 (see FIG. 2) and delivered to the sheet forming machine.

[0046] The sheet forming machine heats and softens the sheet obtained in the sheet forming step, and forms it into food container components by vacuum suction using a mold installed in the forming machine. For example, a single container forming sheet 10-1 can be molded with multiple (e.g., 64) food container components in a continuous grid pattern (e.g., 8 x 8). Then, only the multiple food container components are cut out from the container forming sheet 10-1 to obtain the individual food container components.

[0047] (3) Physical properties [Cold resistance] The food container 30 according to the third embodiment is cold-resistant at a storage temperature of at least -35°C.

[0048] Cold resistance is judged by whether or not cracks occur when the food container is subjected to a drop test under the following conditions. If no cracks are found, the food container is judged to have excellent impact resistance after frozen storage and is evaluated as having cold resistance.

[0049] First, 215 g of frozen dessert (ice cream) and water are placed in the container body 31 according to the third embodiment and sealed with the lid 32. The container is then stored in a freezer at -35°C for at least 24 hours. The container body 31 is then dropped onto an iron plate from a height of 80 cm and 100 cm with the bottom surface 33 facing downwards, and the food container 30 is checked for cracks. The presence or absence of cracks is evaluated according to the following criteria. If no cracks are observed, the food container 30 is evaluated as exhibiting excellent cold resistance at least at a storage temperature of -35°C.

[0050] ○: No visible cracks. ×: Cracks are visually observed.

[0051] [Defect rate] The defective rate indicates the probability of cracking of the container in the above cold resistance test when n=5 (number of experiments).

[0052] 5. Food container according to the fourth embodiment The food container 40 according to the fourth embodiment may be composed of, for example, only the container body 31 of the food container 30 according to the third embodiment. The opening of the food container body is sealed by heat sealing using a top seal material or the like.

[0053] Fig. 4 is a perspective view of a food container according to a fourth embodiment of the present invention. As shown in Fig. 4, food container 40 is composed of a container body 41 and a lid film 42. For example, it is a food container formed from the container forming sheet according to the first embodiment of the present invention. As shown in Fig. 4, container body 41 has a bottom portion 43, container body side portions 44, and a flange portion 45 extending outward from the outer edge of container body side portion 44. The lid film 42 may be made of, for example, a top seal material, and may be heat-sealed to the flange portion 45 of the container body 41 to seal the container body 41 .

[0054] The container body 41 has the same configuration as the container body 31 of the food container 30 according to the third embodiment, and therefore the explanations given in 5. (2) Food container manufacturing method and (3) Physical properties above also apply to the container body 41 of the food container 40 according to the fourth embodiment. Therefore, explanations of the configuration, manufacturing method and physical properties of the container body 41 will be omitted.

[0055] The food container 30 according to the third embodiment of the present invention is formed from the container-forming sheet according to the first embodiment, and therefore has excellent cold resistance and can reduce environmental impact. Furthermore, the top-seal fused surface of the flange 35 is in contact with the outer layer 11 of the container-forming sheet, and the amorphous cyclohexanedimethanol in the outer layer 11 improves the top-sealing property, resulting in excellent sealing performance. [Example]

[0056] The present invention will be described in more detail below with reference to examples. Note that the examples described below are representative examples of the present invention, and the scope of the present invention is not limited to these examples.

[0057] (Test Example 1) Materials for each layer of the container-forming sheet were introduced into the inlets of three cylinders 110 of a twin-screw extruder (TEX77α-31.5AW-2V, manufactured by The Japan Steel Works, Ltd.). Glycol-modified polyethylene terephthalate (PETG(CHDM)) in which the glycol was replaced with cyclohexanedimethanol (PET-G GN-001, manufactured by Eastman Co.) for the outer layer 11 and the inner layer 13 were introduced at 5% by mass of the entire sheet. Also introduced were 40% by mass of glycol-modified polyethylene terephthalate (PETG(IPA)) in which the glycol was replaced with IPA (MA-8334P, manufactured by Unitika Ltd.) and 50% by mass of preformed recycled PET (KA-5, manufactured by Kyoei Sangyo Co., Ltd.), forming the intermediate layer 12. The materials were co-extruded to obtain a container-forming sheet. The resulting sheet was transferred to a sheet-forming machine (TS1300-500, manufactured by GM Engineering Co., Ltd.) to obtain a food container according to the third embodiment. The results of the physical property evaluation of the food container are shown in Table 1.

[0058] (Test Example 2) A container-forming sheet and a food container were obtained in the same manner as in Test Example 1, except that only polystyrene (PET N1: manufactured by Indorama) was used as the container-forming sheet material.

[0059] (Test Example 3) A container-forming sheet and a food container were obtained in the same manner as in Test Example 1, except that only glycol-modified polyethylene terephthalate (PETG) (product name: S2008, manufactured by SK Chemicals) was used as the container-forming sheet material.

[0060] (Test Example 4) A container-forming sheet and a food container were obtained in the same manner as in Test Example 1, except that only cyclohexanedimethanol (trade name: MA8633P, manufactured by Unitika Ltd.) was used as the container-forming sheet material.

[0061] (Test Example 5) A container-forming sheet and a food container were obtained in the same manner as in Test Example 1, except that only isophthalic acid (trade name: MA8334P, manufactured by Unitika Ltd.) was used as the container-forming sheet material.

[0062] The food containers obtained in Test Examples 1 to 5 were evaluated for their physical properties, and the results are shown in Table 1.

[0063] [Table 1]

[0064] As shown in Table 1, Test Example 1, which contained cyclohexanedimethanol in the outer layer 11 and the inner layer 13 and preformed recycled PET and isophthalic acid in the intermediate layer 12, showed no cracks at any height in the drop test and had excellent cold resistance. The defective rate was also 0%.

[0065] In contrast, the single-layer sheet using the cold-resistant material and its container (Test Examples 3 to 5) showed a high number of cracks and a high defect rate, and insufficient cold resistance was not obtained at a storage temperature of -35°C. This indicates that the laminated structure containing cyclohexanedimethanol in the outer layer 11 and the inner layer 13 and preformed recycled PET and isophthalic acid in the intermediate layer 12 contributes to the excellent cold resistance of the present invention. [Explanation of symbols]

[0066] 10-1 Container forming sheet 11 Outer layer 12 Middle Class 13 Inner layer 30 Food Containers 31 Container body 32 Lid 33 Bottom part 34 Container body side part 35 Flange 36 Engagement part 37 Ceiling 40 Food Containers 41 Container body 42 Lid film 43 Bottom part 44 Container body side part 45 flange 100 Extrusion Molding Machine 110 cylinders 120 T-die 120a outlet 130 Inlet 140 screw 200 Cooling device 300 Unloading device

Claims

1. It has a laminated structure in which at least an outer layer, an intermediate layer, and an inner layer are laminated, the intermediate layer comprises recycled polyethylene terephthalate and isophthalic acid; the outer layer and the inner layer contain cyclohexanedimethanol and / or isophthalic acid, The total mass of the outer layer and the inner layer is 2% by mass or more and 80% by mass or less with respect to the entire sheet. Sheet for forming containers.

2. 2. The container-forming sheet according to claim 1, wherein the outer layer and the inner layer are composed solely of cyclohexanedimethanol.

3. The container-forming sheet according to claim 1 , wherein the outer layer and the inner layer do not contain cyclohexanedimethanol.

4. The intermediate layer may contain cyclohexanedimethanol; 2. The container-forming sheet according to claim 1, wherein the total mass of isophthalic acid contained in the intermediate layer when the intermediate layer does not contain cyclohexanedimethanol, or the total mass of cyclohexanedimethanol and isophthalic acid contained in the intermediate layer when the intermediate layer contains cyclohexanedimethanol, is 1% by mass or more and 97% by mass or less with respect to the entire sheet.

5. The container-forming sheet according to any one of claims 1 to 4, wherein the intermediate layer contains scraps and / or waste materials of the container-forming sheet.

6. The container forming sheet according to any one of claims 1 to 4, wherein the recycled polyethylene terephthalate contained in the intermediate layer is recycled polyethylene terephthalate obtained by recycling scraps and / or waste materials generated during the molding of polyethylene terephthalate containers.

7. The polyethylene terephthalate container is a PET bottle, The container-forming sheet according to claim 6, wherein the scraps and / or waste materials are generated during the molding of the PET bottle preforms.

8. 8. The container-forming sheet according to claim 7, wherein the polyethylene terephthalate contained in the intermediate layer is entirely recycled polyethylene terephthalate.

9. A food container formed from the container-forming sheet according to any one of claims 1 to 4.

10. The food container according to claim 9, which has cold resistance at a storage temperature of at least -35°C.

11. A food container component formed from the container forming sheet according to any one of claims 1 to 4.

12. 12. The food container structural member according to claim 11, which has cold resistance at a storage temperature of at least -35°C.

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