WO2021039822A1

WO2021039822A1 - Container

Info

Publication number: WO2021039822A1
Application number: PCT/JP2020/032128
Authority: WO
Inventors: 中川　圭一; 石田　義一; 裕也藤原; 悠介齋藤
Original assignee: 東洋アルミエコープロダクツ株式会社
Priority date: 2019-08-26
Filing date: 2020-08-26
Publication date: 2021-03-04
Also published as: WO2022044377A1; JPWO2022044377A1; CN116096647A; JPWO2021039822A1

Abstract

This container (1) mainly comprises a paper-made substrate layer (10) and a resin layer (11) laminated on an inner surface of the substrate layer (10). A copolymerized polyethylene terephthalate resin constituting the resin layer (11) is a copolymerized polyethylene terephthalate resin obtained by copolymerization with an isophthalic acid, and the copolymerization ratio of the isophthalic acid in the copolymerized polyethylene terephthalate resin is 1 mol% or more and less than 10 mol%. Due to the above configuration, a container having high adhesion between the substrate layer (10) and the resin layer (11) and high heat resistance can be obtained, and thus, molding defect of the container (1) can be prevented and the container is also suitable for use even in a case in which an object in the container has high temperature or in a case in which the object undergoes a firing step.

Description

container

The present invention relates to a container, and more particularly to a container used as a paper cup, a case, etc. for storing beverages, foods, etc.

Conventionally, as a container for storing beverages, foods, etc., there has been a container using a composite base material in which a synthetic resin is laminated on one side or both sides of a paper base material.

Japanese Patent No. 4750909 discloses a container using homopolyethylene terephthalate (PET) as a resin.

Further, Japanese Patent No. 5680917 discloses a container using a copolymerized PET resin (copolymerization component ratio is 10 mol% to 40 mol%) as a resin.

Japanese Patent No. 4750909 Japanese Patent No. 5680917

Homo PET as used in Japanese Patent No. 4750909 has a relatively high melting point of about 255 ° C., and the extrusion temperature of the resin is required to uniformly form a film on the surface of a paper substrate by extrusion lamination. It is necessary to extrude at a high temperature exceeding 310 ° C. However, PET resin is prone to hydrolysis under high temperature conditions. Therefore, it is often assumed that a homo-PET resin having a high melting point originally has higher heat resistance, but if the extrusion temperature is too high, a part of the PET resin on the surface of the container formed after extrusion lamination will be hydrolyzed. As a result, the heat resistance of the portion and the container as a whole is lowered. On the other hand, if the extrusion temperature is lowered in order to reduce the influence of hydrolysis, the heat resistance is increased, but the melt viscosity at the time of extrusion lamination is increased, which makes it difficult to form a uniform film on the paper surface. Even if the film can be formed successfully, the high melt viscosity of the resin causes poor adhesion to the paper when extruded to the paper surface, and when a container is molded using such a composite base material, the container is deteriorated in adhesion. Molding defects and delamination between the paper and the PET resin were likely to occur.

Further, since the copolymerized PET resin of Japanese Patent No. 5680917 has a relatively low melting point of 230 ° C. or lower, the extrusion temperature of the resin can be suppressed to a low level, and hydrolysis under high temperature conditions is less likely to occur. The decrease in adhesion to the paper during extrusion to the paper surface can be reduced. However, since the melting point is as low as 230 ° C. or lower, the heat resistance of the container after molding is inferior. In particular, when filling a container with foods that require cooking such as gratin, for example, in the case of gratin, it is necessary to go through a baking step under high temperature conditions in order to brown the surface after filling the container. Therefore, high heat resistance is required because the temperature is locally high. In addition, the container is also required to have high heat resistance because the container becomes hot even when it is distributed to the market as a food product after being packaged through a baking process and is heated by a general consumer for eating. However, the container of Japanese Patent No. 5680917, which is inferior in heat resistance, could not sufficiently satisfy such a requirement.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a container having high adhesion between a base material layer and a resin layer and high heat resistance.

In order to achieve the above object, the container in the first aspect of the present invention comprises a base material layer made of paper and a resin layer laminated on at least one surface of the base material layer and made of a copolymerized polyethylene terephthalate resin. The copolymerized polyethylene terephthalate resin is a copolymerized polyethylene terephthalate resin obtained by copolymerization with isophthalic acid, and is a copolymer of isophthalic acid in the copolymerized polyethylene terephthalate resin. The polymerization ratio is 1 mol% or more and less than 10 mol%.

With this configuration, the container has high adhesion between the base material layer and the resin layer and high heat resistance.

The container in the second aspect of the present invention has a melting point of 235 ° C. or higher and 250 ° C. or lower in the copolymerized polyethylene terephthalate resin in the configuration of the invention in the first aspect.

With this configuration, the melting point is within a suitable numerical range.

The container in the third aspect of the present invention has a resin layer adhesion to the base material layer of 4N / 50 mm or more in the configuration of the invention in the first aspect or the second aspect.

With such a configuration, the adhesion becomes suitable.

The container in the fourth aspect of the present invention has an isophthalic acid copolymerization ratio of 1.5 mol% or more in the copolymerized polyethylene terephthalate resin in the constitution of the invention in any of the first to third aspects. It is 2.2 mol% or less.

With this configuration, the adhesion between the base material layer and the resin layer and the heat resistance of the container become more preferable.

The container according to the fifth aspect of the present invention is the composition of the invention according to any one of the first to fourth aspects, wherein the copolymerized polyethylene terephthalate resin is of biological origin having a biobase carbon content of 5% or more. It is a biomass polyethylene terephthalate resin.

With this configuration, the amount of fossil resources used can be reduced and carbon neutrality is improved.

The container according to the sixth aspect of the present invention includes a bottom portion and a side wall portion rising from the peripheral edge of the bottom portion in the configuration of the invention in any one of the first to fifth aspects. It is connected by heat bonding.

With this configuration, the bottom and side walls are firmly adhered.

The container in the seventh aspect of the present invention is formed by press molding or bending molding of a single base paper obtained from a composite base material in the constitution of the invention in any of the first to fifth aspects. It is an invention.

With this configuration, the container becomes a press-molded product or a bent-molded product.

As described above, the container in the first aspect of the present invention is a container having high adhesion between the base material layer and the resin layer and high heat resistance, so that it is possible to prevent molding defects of the container and also to prevent molding defects. It is also suitable for use when the contents become hot or undergo a firing process.

In addition to the effects of the invention in the first aspect, the container in the second aspect of the present invention has a melting point within a suitable numerical range, so that the adhesion between the base material layer and the resin layer and the heat resistance of the container are improved. It becomes suitable.

The container in the third aspect of the present invention has favorable adhesion in addition to the effects of the invention in the first or second aspect, so that molding defects of the container can be suitably prevented.

In the container in the fourth aspect of the present invention, in addition to the effect of the invention in any of the first to third aspects, the adhesion between the base material layer and the resin layer and the heat resistance of the container are more preferable. Therefore, it is more convenient to use.

The container in the fifth aspect of the present invention is sustainable because, in addition to the effect of the invention in any of the first to fourth aspects, the amount of fossil resource-derived material used can be reduced and the carbon neutrality is improved. The possibility is improved and it helps to protect the environment.

The container in the sixth aspect of the present invention was stably molded because the bottom portion and the side wall portion were firmly adhered to each other in addition to the effect of the invention in any of the first to fifth aspects. It becomes a container.

The container in the seventh aspect of the present invention is stably molded because the container is a press-molded product or a bent molded product in addition to the effects of the invention in any of the first to fifth aspects. It becomes a container.

It is sectional drawing which shows the whole structure of the container of 1st Embodiment of this invention. FIG. 5 is an enlarged cross-sectional view of the “X” portion shown in FIG. It is sectional drawing which shows the whole structure of the container of the 2nd Embodiment of this invention.

FIG. 1 is a cross-sectional view showing the entire structure of the container according to the first embodiment of the present invention, and FIG. 2 is an enlarged cross-sectional view of the “X” portion shown in FIG.

With reference to these figures, the container 1 is mainly composed of a bottom portion 2 and a side wall portion 3 rising from the peripheral edge of the bottom portion 2.

With reference to FIG. 2, the side wall portion 3 is made of a base material layer 10 made of paper and a copolymerized polyethylene terephthalate resin laminated on the inner side (the surface in the direction in which the contents are stored) of the base material layer 10. It is composed of a composite base material 7 provided with a resin layer 11.

The bottom portion 2 is also made of a composite base material 7 having the same structure as the side wall portion 3, and the bottom portion 2 and the side wall portion 3 are connected by heat adhesion. Specifically, after punching a side wall member (expanded shape of the side wall portion 3) and a bottom surface member (expanded shape of the bottom portion 2) having a predetermined shape from the composite base material 7, the ends of both members are known to be thermally bonded to each other. The container shape is formed by adhering by the method of.

The copolymerized polyethylene terephthalate resin in the present invention is a copolymerized polyethylene terephthalate resin obtained by copolymerization with isophthalic acid (IPA), and the copolymerization ratio of isophthalic acid in the copolymerized polyethylene terephthalate resin is 1 mol% or more. It is less than 10 mol%.

With this configuration, the container has high adhesion between the base material layer 10 and the resin layer 11 and high heat resistance, so that it is possible to prevent molding defects in the container 1 and the contents become hot. It is also suitable for use in cases and when undergoing a firing process.

The copolymerization ratio of isophthalic acid is preferably 1.5 mol% or more and 8 mol% or less, and more preferably 1.5 mol% or more and 2.2 mol% or less. In this way, the effects of improving adhesion and heat resistance are more preferably compatible. Generally, a polyethylene terephthalate resin is obtained by polycondensing an acid component containing terephthalic acid as a main component and a glycol component containing ethylene glycol as a main component, but the copolymerized polyethylene terephthalate resin used in the present invention has an acid component. A copolymerized polyethylene terephthalate resin can be obtained by containing isophthalic acid in addition to terephthalic acid and copolymerizing this isophthalic acid at a predetermined ratio. It should be noted that other acid components may be contained as long as the effects of the present invention are not impaired, and the glycol component may also contain a component such as diethylene glycol in addition to ethylene glycol. Further, as the copolymerized polyethylene terephthalate resin used in the present invention, a plurality of polyethylene terephthalate resins having different copolymerization ratios are mixed and adjusted to a predetermined copolymerization ratio suitable for the present invention. For example, the present invention may be prepared by mixing a homopolyethylene terephthalate resin and a copolymerized polyethylene terephthalate resin in a predetermined ratio to adjust the copolymerization ratio suitable for the present invention, or by mixing polyethylene terephthalate resins having different copolymerization ratios in a predetermined ratio. It is also possible to use a product adjusted to a predetermined copolymerization ratio suitable for the above. The copolymerization ratio of isophthalic acid can be calculated by subjecting the ^{copolymerized polyethylene terephthalate resin to qualitative / quantitative analysis by 1 H-NMR spectrum measurement.} More specifically, the estimated ^{1 H-NMR} from the spectrum obtained by the spectrum measurement during copolymerization polyethylene terephthalate resin monomer units composed of monomer units and isophthalic acid composed of terephthalic acid, respectively, the peak of the spectrum The composition ratio (molar ratio) of each monomer unit in the copolymerized polyethylene terephthalate resin is calculated from the area ratio, and the "isophthalic acid monomer unit molar ratio" to the "total of the terephthalic acid monomer unit molar ratio and the isophthalic acid monomer unit molar ratio". It can be obtained by calculating the ratio (%) of.

Further, the copolymerized polyethylene terephthalate resin in the present invention preferably has a melting point of 235 ° C. or higher and 250 ° C. or lower. With this configuration, the melting point is within a suitable numerical range, and the melting point itself is sufficiently high while keeping the extrusion temperature at the time of extrusion lamination relatively low. Therefore, the base material layer 10 and the resin layer 11 are combined. Adhesion and heat resistance of the container 1 are preferable. The melting point can be measured by differential scanning calorimetry (DSC).

Further, the adhesion of the resin layer 11 to the base material layer 10 in the present invention is preferably 4N / 50 mm or more. With such a configuration, the adhesiveness becomes preferable, so that molding defects of the container 1 can be preferably prevented. From the viewpoint of molding defects, the higher the value of adhesion is, the better, so there is no particular preferable upper limit of adhesion, but considering the ease of disassembling and disassembling the container to reduce the volume of dust after using it as a container. Then, it may be about 20 N / 50 mm or less. The adhesion can be measured by the measuring method in the examples described later.

Further, the polyethylene terephthalate resin in the present invention is preferably a biomass polyethylene terephthalate resin derived from a living organism (derived from a biomass resource) having a biobase carbon content of 5% or more. The polyethylene terephthalate resin is a resin obtained by polycondensing ethylene glycol and terephthalic acid as main components, and most of them (the above-mentioned Japanese Patent No. 4750909 and Japanese Patent No. 5680917). ) Is derived from fossil resources. By using this as a biomass polyethylene terephthalate resin obtained from a biological raw material such as sugar cane, the amount of fossil resource-derived material used can be reduced and carbon neutrality is improved, which improves sustainability and contributes to environmental conservation.

In the present invention, the biobase carbon content, which is an index indicating the proportion of the biological raw material in the copolymerized polyethylene terephthalate resin, is preferably 5% or more, and more preferably 15% or more. The higher the bio-based carbon content, the smaller the proportion of fossil resource-derived raw materials, making the container useful for environmental conservation. On the other hand, as the proportion of the biobase carbon content increases, the cost also increases, so that it is more preferably within an appropriate range. The bio-based carbon content can be indicated by the value of the C14 content obtained by the radiocarbon (C14) measurement method conforming to ISO-16620-2 (equivalent to the ASTM-D6866 standard). That is, since C14 is hardly contained in fossil resources, while C14 is contained in a certain ratio (105.5 pMC) in biological resources, assuming that the content of C14 in the copolymerized polyethylene terephthalate resin is PC14, The biobase carbon content can be calculated by the following formula.

Bio-based carbon content (%) = PC14 / 105.5 × 100
Next, FIG. 3 is a cross-sectional view showing the entire structure of the container according to the second embodiment of the present invention.

Since the container 21 according to the second embodiment of the present invention has basically the same configuration as the container 1 according to the first embodiment described above, the differences will be mainly described below.

With reference to the figure, the container 21 is formed by press molding a single base paper obtained from the composite base material 27 (similar to the composite base material 7 in the first embodiment described above). Is. Specifically, a container 21 having a bottom portion 22 and a side wall portion 23 rising from the peripheral edge of the bottom portion 22 is formed by punching a sheet of base paper having a predetermined shape obtained from the composite base material 27 and then press-molding the base paper. Will be done.

Further, although not shown, the container according to the third embodiment is determined by bending a single base paper obtained from the composite base material (similar to the composite base material 7 in the first embodiment described above). It is formed by molding into the shape of a container. Specifically, the bottom and the bottom are formed by punching out a sheet of base paper having a predetermined shape obtained from the composite base material and then bending the base paper so as to form a side wall portion that rises from the periphery of the bottom and the bottom. A container is configured with a side wall that rises from the periphery of the.

The container according to each embodiment of the present invention can be used for various purposes, and the use is not limited, but can be used, for example, for storing food. Further, it is particularly suitable for storing foods that are heated under high temperature conditions after filling the container with foods. Specifically, it can be used even under high-temperature heating conditions of 100 ° C. or higher, and can be rephrased as a heat-resistant paper container. It can also be used for cooking in an oven (including a toaster, grill, etc.) at 200 ° C. or higher.

Further, in the container according to each embodiment of the present invention, the composition of the paper constituting the composite base material is not particularly limited, and pure white roll paper, kraft paper, parchment paper, ivory paper, depending on the desired application. , Manila paper, card paper, cup paper and the like can be used. The basis weight of the paper is preferably ^{150 g / m 2} to 500 g / m ^2. With such a configuration, the molding of the container can be facilitated and the cost of the container can be suppressed.

Further, in the container according to each embodiment of the present invention, the method of laminating the polyethylene terephthalate resin on paper is not particularly limited, and extrusion lamination, thermal lamination, dry lamination, wet lamination and the like can be exemplified. In the present invention, it is preferable to use extrusion lamination because it is suitable for mass production, is excellent in terms of cost, and can be directly laminated without using an anchor coat or the like. However, it does not exclude the formation of an anchor coat layer on the paper in advance during extrusion lamination.

Further, in the container according to each embodiment of the present invention, the thickness of the resin layer is not particularly limited, but is preferably 6 μm to 50 μm. Within this range, the container can be imparted with desired heat resistance. Further, when the resin layers of the composite base material are heat-bonded to each other in container molding, the temperature of the resin can be easily raised uniformly, and the adhesion can be made uniform. Further, it is possible to suppress the occurrence of tunneling and pinholes in the resin layer during thermal adhesion.

Further, in the container according to each embodiment of the present invention, the resin layer is formed on the inner side of the base material layer, but it suffices if it is formed on at least one side, and is formed on both sides. You may.

Further, in the container according to each embodiment of the present invention, an anchor coat layer may be interposed between the base material layer and the resin layer as described above as long as the object of the present invention is not impaired. , A print layer may be formed. Further, the paper of the base material layer may be subjected to corona treatment.

Further, in the container according to each embodiment of the present invention, a chain extender, an ultraviolet absorber, a lubricant, an antistatic agent, and a heat stabilizer are used in the copolymerized polyethylene terephthalate resin as long as the object of the present invention is not impaired. , Antioxidants, pigments, dyes, antioxidants, light stabilizers, plasticizers and other various additives may be contained in appropriate amounts.

Further, in the container according to each embodiment of the present invention, the method for producing the copolymerized polyethylene terephthalate resin obtained by copolymerization with isophthalic acid is not particularly limited, and if copolymerization is carried out under known methods and conditions. As described above, a plurality of polyethylene terephthalate resins may be mixed to adjust the copolymerization ratio.

Hereinafter, the present invention will be specifically described based on Examples. The embodiment of the present invention is not limited to the examples.

(Preparation of Examples)
First, a plurality of types of copolymerized polyethylene terephthalate resins obtained by copolymerizing with isophthalic acid at different ratios or mixing a plurality of polyethylene terephthalate resins having different copolymerization ratios to adjust the copolymerization ratio to a predetermined value are obtained. Got ready. Biomass polyethylene terephthalate resin was prepared as the resin used in Examples 1 and 3, and homopolyethylene terephthalate resin was prepared as the resin used in Comparative Example 1. ¹ Results of calculating the ratio (%) of "isophthalic acid monomer unit molar ratio" to "total of terephthalic acid monomer unit molar ratio and isophthalic acid monomer unit molar ratio" by subjecting to qualitative and quantitative analysis by H-NMR measurement. The copolymerization ratios of isophthalic acid in each of the copolymerized polyethylene terephthalate resins were 2.0% (Example 1), 1.6% (Example 2), 5.0% (Example 3), and 7.5, respectively. % (Example 4), 9.2% (Example 5), 14.1% (Comparative Example 2) and 10.5% (Comparative Example 3). The copolymerization ratio of isophthalic acid in the homopolyethylene terephthalate resin was 0% (Comparative Example 1). Moreover, each melting point was measured by a commercially available differential scanning calorimeter. Further, the biobase carbon content was measured by a radiocarbon (C14) measurement method compliant with ISO-16620-2 (equivalent to the ASTM-D6866 standard), and was determined by the above-mentioned biobase carbon content calculation formula.

A paper having a basis weight of 230 g / m ² is used as a base material layer, and each type of polyethylene terephthalate resin described above is applied to one surface thereof by an extrusion lamination method in Example 1, Example 2, Example 4, and Comparative Examples 1 to 3. Each composite substrate was prepared by coating with a thickness of 30 μm, a thickness of 40 μm in Example 3, and a thickness of 20 μm in Example 5. The thickness of the polyethylene terephthalate resin was measured by observing the cross section of the composite base material with a commercially available microscope.

By punching out a side wall member and a bottom surface member having a predetermined shape so as to form a container having a size capable of accommodating 300 g of white sauce, which will be described later, from each of the composite base materials of each type, and combining these and heat-bonding them together. Containers of Examples 1 to 5 and Comparative Examples 1 to 3 were prepared.

(Adhesion test)
A test piece having a size of 50 mm × 150 mm is cut out from each of the composite base materials of each type prepared above, and a peeling test is performed at a speed of 100 mm / min with 180 ° peeling to obtain a base material layer and resin of the composite base material. Adhesion with the layer was tested.

As a measuring device, a product number MAX-R2KN-B manufactured by Japan Measurement System Co., Ltd. was used. The ideal adhesion is complete delamination of paper, but it was judged that there would be no problem if there was strength to delaminate some paper. The adhesion was evaluated as × (unsuitable) for less than 4N / 50 mm, Δ (available) for 4N / 50 mm or more and less than 7N / 50 mm, and ○ (suitable) for 7N / 50 mm or more.

(Heat resistance test)
The following two types of heat resistance tests were performed using each type of container prepared above.

(1) Heating test using a microwave oven Put 100 g of water in each container, heat it in a microwave oven (manufactured by Sanyo Electric Co., Ltd., model number: EMO-FM23C, without turntable) at 500 W for 3 minutes, then take it out and put water in the container. After leaving the container for 12 hours with the container in place, the presence or absence of water leakage from the container and the surface condition of the resin layer constituting the container were visually confirmed. The test was performed with the number of n in each container = 5. In the water leakage evaluation, it was judged as 〇 (suitable) when no water leakage occurred in any of the five, and × (inappropriate) when water leakage occurred in even one of the five. In addition, in the evaluation of the surface condition of the resin layer, if no abnormality such as air bubbles or tears is found on the surface of the resin layer that constitutes the container, 〇 (suitable), even one out of five constitutes the container. When an abnormality such as air bubbles or tears was found on the surface of the resin layer, it was judged as × (inappropriate).

(2) Baking test after filling the container with white sauce After filling each container with 300 g of white sauce manufactured by Heinz Japan Ltd., the filled container is placed in an oven (model number: FSCC101) manufactured by Fujimac Co., Ltd. The baking test was carried out by heating at heating temperatures of 200 ° C. and 260 ° C. under the condition of heating time of 5 minutes. The test was carried out at each temperature with n number = 5. After the firing test, the white sauce is taken out from the container, and the presence or absence of delamination (peeling at the interface between the paper and the resin layer, which is the base material layer) between the base material layer (paper) and the resin layer of the composite base material constituting the container is present. Was visually confirmed. The case where delamination did not occur in any part of the container was judged as 〇 (suitable), and the case where delamination occurred in any part of the container was judged as × (unsuitable).

Table 1 below shows the composition of each type of container (resin, composite base material) and the results of each test.

As shown in Table 1, in Examples 1 to 5 in which the copolymerization ratio of isophthalic acid is within a suitable range, the adhesion is suitable, and the heat resistance is also good in the firing test at a heating temperature of 200 ° C. There was no problem. In particular, the heat resistance of Examples 1 to 4 in which the copolymerization ratio of isophthalic acid was 1.5 mol% or more and 8 mol% or less was a suitable result even in the firing test at a heating temperature of 260 ° C.

Further, in Example 1 having a biobase carbon content of 17% and Example 3 having a biobase carbon content of 6.2%, adhesion and heat resistance are preferable as in the other examples having a biobase carbon content of 0%. It was confirmed that.

As described above, the container according to the present invention is suitable as, for example, a paper cup or a case for storing beverages, foods, and the like.

Claims

A container composed of a composite base material (7) having a base material layer (10) made of paper and a resin layer (11) laminated on at least one surface of the base material layer and made of a copolymerized polyethylene terephthalate resin. (1)
The copolymerized polyethylene terephthalate resin is a copolymerized polyethylene terephthalate resin obtained by copolymerization with isophthalic acid.
A container in which the copolymerization ratio of the isophthalic acid in the copolymerized polyethylene terephthalate resin is 1 mol% or more and less than 10 mol%.
The container according to claim 1, wherein the copolymerized polyethylene terephthalate resin has a melting point of 235 ° C. or higher and 250 ° C. or lower.
The container according to claim 1 or 2, wherein the adhesion of the resin layer to the base material layer is 4N / 50 mm or more.
The container according to any one of claims 1 to 3, wherein the copolymerization ratio of the isophthalic acid in the copolymerized polyethylene terephthalate resin is 1.5 mol% or more and 2.2 mol% or less.
The container according to any one of claims 1 to 4, wherein the copolymerized polyethylene terephthalate resin is a biological biomass polyethylene terephthalate resin having a biobase carbon content of 5% or more.
The bottom portion (2) and the side wall portion (3) rising from the peripheral edge of the bottom portion are provided.
The container according to any one of claims 1 to 5, wherein the bottom portion and the side wall portion are connected by thermal adhesion.
The container according to any one of claims 1 to 5, which is formed by press molding or bending molding of one base paper obtained from the composite base material.