JP7404397B2 - Container with improved printability and heat insulation properties and method for manufacturing the same - Google Patents

Description

The present invention relates to a container with excellent printability and/or heat insulation properties, and a method for manufacturing the same.

Products used as disposable beverage containers are divided into foam and non-foam types. Generally, foam containers are made by extruding polystyrene mixed with foaming gas, but such foam containers can maintain a relatively thick thickness, maintain their shape, and Although it has the advantages of high heat insulation and price competitiveness, it is less safe for the human body and less suitable for printing because it releases substances harmful to the human body at high temperatures, so it is necessary to introduce a separate printing layer on the surface. , or the hassle of having to wrap it in printed film. As a result, foam container materials that utilize polyethylene terephthalate (PET), which does not release harmful substances at high temperatures, are increasingly being used. There are difficulties in manufacturing thermoformed containers due to poor molding.

In addition, as non-foam containers, cups made of highly processable paper or products made of heat-stable polypropylene film molded into a cup shape are used. The rate of shape change is small and no harmful substances are detected, but the price is high and the insulation properties are extremely low, making it difficult for users to grasp the container with their hands when containing high-temperature contents, and the temperature of the contents is easily cooled down. There is a problem.

In recent years, as concerns about the environment and the quality of personal life have increased, it is important to consider the need for materials that can be reused and recycled, are environmentally friendly, and are harmless to the human body while keeping the state of the materials contained in the containers intact for long periods of time. There is an emerging need for multifunctional storage containers.

Therefore, it has excellent heat resistance and/or insulation properties, and can not only keep the temperature of hot and/or cold beverages constant for a long time, but also has excellent surface printability, and is cost-competitive while keeping the human body safe. There is a need for the development of safe and environmentally friendly beverage containers.

The purpose of the present invention is to be cost-competitive, safe for the human body, environmentally friendly, have excellent heat resistance and/or insulation properties, and be able to maintain a constant temperature even when hot and/or cold liquids are put in it. An object of the present invention is to provide a container and a method for manufacturing the same.

Another object of the present invention is to provide a container with excellent surface printability and a method for manufacturing the same.

Still another object of the present invention is to provide a container with excellent shape stability against heat and a method for manufacturing the same.

In order to achieve the above-mentioned object, the present invention provides a container comprising a main body including a polyester foam sheet and a bottom portion located at the lower end of the main body and including the polyester foam sheet, the container being formed by press-molding the foam sheet. The container is not manufactured in one piece, but the main body and bottom, which are each made separately, are joined together to form a sealed structure, and after 3 minutes of filling the container with 100°C water, the outer surface of the main body and the inner surface of the container are sealed. To provide a container in which the temperature difference of water is 10°C or more.

In the present invention, the main body and the bottom portion may be joined by one or more of heat fusion bonding, ultrasonic bonding, an adhesive, and an adhesive sheet.

In the present invention, the adhesive or the adhesive sheet may contain a low melting point polyester resin, and the low melting point polyester resin may contain repeating units represented by the following chemical formulas 1 and 2, and have a softening point of 100°C to 130°C. ℃ or a glass transition temperature of 50°C to 80°C.

[Case 1]

[Case 2]

In Chemical Formulas 1 and 2, m and n represent the molar fraction of the repeating unit contained in the low melting point polyester resin, and based on m+n=1, n may be 0.05 to 0.5. good.

In the present invention, polyesters include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polyethylene naphthalate (PEN), polyethylene adipate (PEA), polylactic acid (PLA), and polyglycolic acid. (PGA) may be used.

In the present invention, the container may be a beverage container, the average thickness of the polyester foam sheet may be 0.5 mm to 3 mm, and the height (H) of the side surface of the main body may be 5 cm to 20 cm. The ratio (H/D) of the side height (H) of the main body to the diameter (D) of the bottom may be 0.5 or more, and the ratio of the average thickness of the main body and the bottom (body/bottom) may be 0.8 or more.

According to a first embodiment of the present invention, the polyester foam sheet may include a foam layer and a skin layer, and the centerline surface roughness (R _a ) of the skin layer is between 0.1 μm and 2.5 μm. The surface tension of the foam sheet may be 25 mN/m or more.

According to a first embodiment of the invention, the crystallinity of the foam layer may be between 1% and 20%, and the average cell density of the foam layer is between 100 cells/cm ² and 25,000 cells/cm ² The average cell size of the skin layer may be 100 μm or less.

According to a first embodiment of the present invention, the polyester foam sheet may further include a printing layer on the skin layer.

According to a second embodiment of the invention, the polyester foam sheet may be composed of a single layer, and the polyester foam sheet may be a heat-treated foam sheet.

According to a second embodiment of the present invention, the average cell density of the polyester foam sheet may be between 100 cells/cm ² and 25,000 cells/cm ² , and the crystallinity of the heat-treated polyester foam sheet is The volume change rate of the container may be 5% or less after the container is left in an oven at 100° C. for 3 minutes.

The present invention also provides a method for manufacturing the above-mentioned container, which includes the steps of separating and producing or cutting the polyester foam sheet into the shapes of the main body and the bottom, and joining the main body and the bottom. A method for manufacturing a container is provided.

In the present invention, after applying an adhesive containing a low melting point polyester resin to the inside of the lower end of the main body, the side surfaces in the thickness direction of the bottom, or both, or laminating an adhesive sheet, the bottom is attached to the inner lower end of the main body. After pushing up and inserting the body, a temperature of 100° C. to 400° C. may be applied to the joint portion between the inserted bottom and the main body to join them.

According to the first embodiment of the present invention, when manufacturing a polyester foam sheet, after forming a foam layer, the surface of the foam layer may be cooled to form a skin layer.

According to a first embodiment of the invention, a printing layer may be formed on the skin layer.

According to a second embodiment of the present invention, the method may further include heat treating the polyester foam sheet at 150° C. to 300° C. for 10 seconds to 100 seconds before cutting.

The container according to the present invention has a simple structure in which the main body and bottom part including a polyester foam sheet are joined, so it is not only economical, environmentally friendly, and harmless to the human body, but also allows for the creation of a deep container during processing. It has the advantage that it has excellent heat resistance and/or heat insulation, can maintain the temperature of hot and/or cold beverages for a long time, and can be easily printed on the outer surface of the container.

In addition, the container according to the present invention is not only economical, environmentally friendly, and harmless to the human body by using a highly crystalline polyester foam sheet, but also allows for the production of deep containers. The container has excellent heat resistance and insulation properties, and has the advantage of being able to maintain temperature for a long time when used for hot and/or cold beverages.

Because the invention is susceptible to various modifications and embodiments, specific embodiments will be described in detail.

However, it is to be understood that this invention is not limited to a particular embodiment, but is intended to include all modifications, equivalents, and alternatives that fall within the spirit and technical scope of the invention.

In the present invention, terms such as "comprising" or "having" specify the presence of features, numbers, steps, acts, components, parts, or combinations thereof that are described in the specification. It is to be understood that this does not exclude in advance the existence or possibility of the addition of one or more other features, figures, steps, acts, components, parts or combinations thereof.

In the present invention, the term "cell" refers to a microstructure expanded by foaming within a polymer. Cells may include closed cells and/or open cells.

The present invention relates to a container and a method for manufacturing the same.

In recent years, interest in the quality of life of individuals has increased as well as concern for the environment, and products that can be reused and recycled, are environmentally friendly, harmless to the human body, are easy to process such as printing, and have a good design quality. There is an increasing demand for multi-functional containers that are of excellent quality and capable of preserving the state of the substances contained in them for long periods of time, but the reality is that no materials have yet been developed that meet these demands. be.

Therefore, the present invention provides a container with excellent printability, heat insulation, heat resistance, etc., and a method for manufacturing the same.

Since the container according to the present invention has a simple structure in which the main body including a polyester foam sheet and the bottom are joined, it is not only economical, environmentally friendly, and harmless to the human body, but also has excellent heat resistance and/or insulation properties. This has the advantage that the temperature of hot and/or cold beverages can be maintained for a long time, and that it is easy to print on the outer surface of the container during processing.

The present invention will be explained in more detail below.

[container]
The container according to the invention may be a food container, a packaging container or the like, in particular a beverage container.

The container according to the present invention is a container comprising a main body including a polyester foam sheet and a bottom portion located at the lower end of the main body and including a polyester foam sheet, wherein the container is not manufactured in one piece by press molding of the foam sheet; The container is characterized in that a main body and a bottom, which are separately manufactured, are joined to each other to form a sealed structure.

When a container is manufactured through press molding (thermoforming), physical properties such as heat insulation and printability may deteriorate. Further, when manufacturing a container with a deep shape such as a beverage container, there is difficulty in press molding. At this time, press molding is a method in which the foam sheet is placed between the female mold and the male mold of a press molding device, and then the female mold and the male mold are pressurized to integrally mold the main body and bottom of the container. It is.

In the present invention, by simply cutting the foam sheet into a main body and a bottom part and then joining them without using press molding, it is possible to improve physical properties such as heat insulation and printability, and also to form a deep shape. Containers can be easily produced.

Regarding heat insulation, after 3 minutes have elapsed after filling the container with water at 100°C, the temperature difference between the outer surface of the main body and the water inside the main body may be 10°C or more. Specifically, under the conditions of room temperature (23 ± 5 °C) and Josho (1 ± 0.2 atm), water at 60 to 120 °C is placed in a container at 70 ± 20% (v/v) of the total volume inside the container. v) After 3 minutes have passed, the temperature difference between the water in the container and the outer surface of the container may be 10°C or more, specifically, 10 to 35°C, 10°C. It may be ~30°C, 10-20°C, 10-18°C, 10-16°C, 13-40°C, 15-35°C, 20-32°C, or 21.5-30°C. The temperature difference between the water in the container and the outside surface of the container is 10℃ or more, which means that the temperature difference between the inside and outside of the container is maintained relatively high, and the container has excellent heat insulation properties. , indicating that this effectively preserves the temperature of the beverage in the container.

The shape of the body is not particularly limited, and when considering formability and workability, the body may be a cylinder or an n-sided (n = integer from 3 to 20) column with the same shape and size at the upper and lower ends of the body. , the shape of the upper and lower ends of the main body is the same, but the length or diameter of the upper end is larger than the length or diameter of the lower part. Integer) It may be tubular in the shape of a frustum. For example, the main body may be cylindrical or may have a truncated conical shape with a wide top and a narrow bottom.

The bottom portion may be joined to the inside of the lower end of the tubular body to form a structure that seals the lower end of the tubular body, whereby the container of the present invention may provide a space for containing a liquid substance. To this end, the bottom may have the same shape as the inside of the lower end of the body, and its size may be the same as or smaller than the inside of the lower end of the body. The bottom portion is located at the lower end of the main body, but may be located at the extreme end of the lower end, or may be located a short distance upward from the end. If it is located at the extreme end, there may be no space at the bottom of the bottom, and if it is located a little upward from the end, there may be some space at the bottom of the bottom.

The height (H) of the side surface of the main body may be 5 cm to 20 cm, specifically, 5 cm to 18 cm, 5 cm to 16 cm, 5 cm to 14 cm, 5 cm to 12 cm, 5 cm to 10 cm, 8 cm to 20 cm, 10 cm. ~20 cm, 12 cm to 20 cm, 14 cm to 20 cm, 16 cm to 20 cm, 7 cm to 18 cm, 7 cm to 16 cm, or 7 cm to 14 cm.

The ratio of the height (H) of the side surfaces of the main body to the size of the bottom portion may be constant. Specifically, when the shape of the main body is a cylinder or a tubular shape of a truncated cone, the shape of the bottom joined to the inside of the lower end of the main body is circular, and in this case, the height (H) of the side surface of the main body The ratio (H/D) of the bottom diameter (D) is 0.5 or more, more specifically, 0.5 to 5, 0.5 to 4, 0.5 to 3, 0.5 to 2. , 0.5-1.5, 1-5, 1.5-5, 2-5, 2.5-5, 3-5, 3.5-5, 4-5, 0.9-1.5 , 0.7-3, 0.9-3, 1-3, 1.1-4, 1.1-2, 1.1-1.5, 1.2-3, 1.2-2.5 , 1.2-2, 1.2-1.8, 1.2-1.5, 1.3-1.8, 1.3-1.6, 1.4-1.9, 1.4 ~1.7 or 1.5-1.8. The height (H) of the side surface of the main body means the vertical height, and even if the main body has a tapered structure, it does not mean the length from the top end to the bottom end of the main body, but the vertical height. If the bottom is not circular, for example polygonal or oval, then an equivalent diameter may apply. In the present invention, since containers are manufactured by cutting and joining without press forming, containers with a deep depth (height), that is, containers with a large H/D ratio can be easily manufactured.

The average thickness ratio of the body and the bottom (body/bottom) may be 0.8 or more, specifically 0.8 to 1.2, 0.9 to 1.1 or 0.95. ˜1.05, and in some cases may be close to 1. This means that the containers according to the invention are manufactured by cutting and joining rather than by high temperature and pressure forming such as press molding.

The main body and the bottom portion may be joined by one or more of thermal bonding, ultrasonic bonding, an adhesive, and an adhesive sheet. That is, the bottom portion may be bonded by heat fusion or ultrasonic bonding, or may be bonded to the inside of the lower end portion of the main body with an adhesive or an adhesive sheet. More specifically, the bottom part is pushed up and inserted inside the bottom end of the main body, and an adhesive or an adhesive sheet containing a low melting point polyester resin is located between the inserted bottom part and the inside of the bottom end of the main body. The bottom and the main body can be joined together, thereby completely sealing the lower end of the container.

The low melting point polyester resin contains repeating units represented by the following chemical formulas 1 and 2, and can strengthen the adhesive strength of the main body and bottom portion including the polyester resin foam sheet.

[Case 1]

[Case 2]

In Chemical Formulas 1 and 2, m and n represent the molar fraction of the repeating unit contained in the low melting point polyester resin, and based on m+n=1, n is 0.05 to 0.5, 0.05 to 0.4, 0.1-0.4, 0.15-0.35 or 0.2-0.3, m is 0.5-0.95, 0.6-0.95 , 0.6-0.9, 0.65-0.85 or 0.7-0.8.

Specifically, the low melting point polyester resin may be a copolymerized polyester resin having a structure containing repeating units represented by Chemical Formulas 1 and 2. The repeating unit represented by Chemical Formula 1 is a repeating unit of polyethylene terephthalate (PET), and the repeating unit represented by Chemical Formula 2 functions to improve the tearing characteristics of a polyester resin containing PET repeating units. Specifically, the repeating unit represented by Chemical Formula 2 contains a methyl group (-CH ₃ ) as a side chain in the ethylene chain bonded to terephthalate to secure a space so that the main chain of the polymerized resin can rotate. Accordingly, the softening point (Ts) and/or glass transition temperature (Tg) can be adjusted by increasing the degree of freedom of the main chain and decreasing the crystallinity of the resin. This can have the same effect as using isophthalic acid (IPA) containing asymmetric aromatic rings to reduce the crystallinity of conventional crystalline polyester resins.

When the molar fraction of the total resin is 1, the low melting point polyester resin may contain 0.5 to 1 repeating unit represented by Chemical Formulas 1 and 2, specifically, 0.55 to 1,0 .6-1, 0.7-1, 0.8-1, 0.9-1, 0.5-0.9, 0.5-0.85, 0.5-0.7, or 0. It may contain 6 to 0.95.

The mole fraction (n) of the repeating unit represented by chemical formula 2 contained in the low melting point polyester resin is calculated as follows: when the total mole fraction of the repeating units represented by chemical formula 1 and chemical formula 2 is 1 (m+n=1 ), 0.01 to 1, specifically 0.05 to 1, 0.05 to 0.9, 0.05 to 0.8, 0.05 to 0.7, 0. 05-0.6, 0.05-0.5, 0.05-0.4, 0.05-0.3, 0.1-0.3, 0.55-1, 0.6-1, 0.7-1, 0.8-1, 0.5-0.9, 0.5-0.85, 0.5-0.7, 0.6-0.95, 0.05-0. 4, 0.15 to 0.35, or 0.2 to 0.3. m may be 0 to 0.99, specifically 0 to 0.95, 0.1 to 0.95, 0.2 to 0.95, 0.3 to 0.95, 0. 4-0.95, 0.5-0.95, 0.6-0.95, 0.7-0.95, 0.7-0.9, 0-0.45, 0-0.4, 0-0.3, 0-0.2, 0.1-0.5, 0.15-0.5, 0.3-0.5, 0.05-0.4, 0.6-0. 95, 0.65 to 0.85, or 0.7 to 0.8. Here, a polyester resin in which the mole fraction of the repeating unit represented by Chemical Formula 1 is 0 (m=0) and the mole fraction of the repeating unit represented by Chemical Formula 2 is 1 (n=1), It may have a structure containing a repeating unit represented by Chemical Formula 2 as a main chain.

The melting point (Tm) of the low melting point polyester resin may be 180° C. to 250° C., or there may be no melting point. Specifically, the melting point (Tm) is 180 °C to 250 °C, 185 °C to 245 °C, 190 °C to 240 °C, 180 °C to 200 °C, 200 °C to 230 °C, 195 °C to 230 °C, or It doesn't have to exist.

The softening point of the low melting point polyester resin may be 100°C to 130°C, specifically, 110°C to 120°C, 115°C to 125°C, 118°C to 128°C, 120°C to 125°C, 121°C The temperature may be between 124°C and 124°C, between 124°C and 128°C, or between 119°C and 126°C.

The low melting point polyester resin may have a glass transition temperature (Tg) of 50°C or higher. Specifically, the glass transition temperature may be 50°C to 80°C, more specifically, 50°C to 60°C, 60°C to 70°C, 70°C to 80°C, 50°C to 55°C, 55°C. °C to 60 °C, 60 °C to 65 °C, 65 °C to 70 °C, 68 °C to 75 °C, 54 °C to 58 °C, 58 °C to 68 °C, 59 °C to 63 °C, or 55 °C to 70 °C Good too.

The low melting point polyester resin contains repeating units represented by chemical formula 2, and the softening point (Ts) and/or glass transition temperature (Tg) of the polyester resin can be adjusted within the range, so it can be thermally bonded at 100°C to 200°C. It can embody sexuality. The glass transition temperature, softening point, melting point, etc. may be measured using a differential scanning calorimeter (DSC), a melting point meter, a thermomechanical analyzer (TMA), or the like.

Containers according to the invention may be constructed from polyester foam sheets. The main body and bottom are
Each may be constructed from the same or different polyester foam sheets, preferably the same PET foam sheets. Here, the polyester foam sheet is a single sheet mainly composed of polyester resin, and has the advantage of being inexpensive, not emitting harmful substances to the human body even at high temperatures, and being environmentally friendly. Here, "consisting as a main component" means 90 parts by weight or more, 95 parts by weight or more, 96 parts by weight or more, 97 parts by weight or more, 98 parts by weight or more, or 99 parts by weight or more, based on the total weight of the foam sheet. This means that it contains polyester resin.

Polyester resins include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polyethylene naphthalate (PEN), polyethylene adipate (PEA), polylactic acid (PLA), and polyglycolic acid (PGA). One or more types selected from these may be used. Preferably, polyethylene terephthalate (PET) may be used. Polyester foam sheets contain polyester resin as a main component, are inexpensive, do not emit substances harmful to the human body even at high temperatures, and have the advantage of being environmentally friendly.

The average thickness of the polyester foam sheet may be 0.5 mm to 3 mm. Specifically, the thickness of the foam sheet is 0.5 mm to 2.5 mm, 1 mm to 2.5 mm, 1.5 mm to 2.5 mm, 2 mm to 2.5 mm, 0.5 mm to 2 mm, and 0.5 mm to 1.5 mm. It may be 5 mm, 0.5 mm to 1 mm, 1 mm to 2 mm, 1 mm to 1.5 mm, or 0.8 mm to 1.7 mm.

According to a first embodiment of the invention, the polyester foam sheet may include a foam layer and a skin layer. The skin layer may be formed on one or both sides of the foam layer. The skin layer may be a foam or coating layer containing polyester resin. The foam layer and the skin layer may be formed separately and then laminated, or the foam layer may be coated with the skin layer. Preferably, the foam layer and the skin layer may be formed integrally, and for example, a skin layer may be formed on the surface of the foam layer by cooling the surface of the foam layer during production of the foam sheet. The foam layer and the skin layer may be classified by cell size or the like; for example, the cell size of the foam layer may be relatively large, and the cell size of the skin layer may be relatively small.

When the skin layer is a foam, the average cell size of the skin layer may be 100 μm or less. Specifically, the average cell size of the skin layer is 80 μm or less, 60 μm or less, 40 μm or less, 20 μm or less, 0.1 to 100 μm, 5 to 80 μm, 10 to 50 μm, 10 to 30 μm, 40 to 90 μm, or 50 to 100 μm. In some cases, since cells are not formed like a film, the cell size may be close to 0 μm (non-foamed material). In the present invention, by including such a skin layer, the foam sheet has excellent surface uniformity. If the average cell size of the skin layer is too large, the centerline surface roughness (R _a ) of the skin layer may become excessively large. The average cell size of the skin layer may be determined through scanning electron microscopy (SEM) images.

The polyester resins contained in the foam layer and skin layer may be the same or different. Preferably, the foam layer and skin layer may all be composed of PET.

The centerline surface roughness (R _a ) of the skin layer may be between 0.1 μm and 2.5 μm. Centerline surface roughness (R _a ) may be according to KS B 0161. Specifically, the centerline surface roughness (R _a ) of the skin layer is 0.1 μm to 2.1 μm, 0.1 μm to 1.6 μm, 0.9 μm to 1.5 μm, 0.1 μm to 1.1 μm, 0.3 μm to 1.4 μm, 0.5 μm to 1.2 μm, 0.8 μm to 1.1 μm, 0.1 μm to 0.7 μm, 0.3 μm to 0.8 μm, 1.8 μm to 2.2 μm, 0. It may be 5 μm to 2 μm, 0.5 μm to 1 μm or 1 μm to 2 μm. By controlling the centerline surface roughness (R _a ) of the skin layer within such a range, the surface area is increased and the absorbency and/or adhesion to ink, that is, printability, is improved when forming an ink layer. be able to. The surface roughness may be measured using an illuminance meter or the like.

The surface tension of the foam sheet including the foam layer and the skin layer may be 25 mN/m or more. Specifically, the surface tension of the foam sheet is 28 mN/m or more, 25 mN/m to 40 mN/m, 28 mN/m to 40 mN/m, 30 mN/m to 40 mN/m, 25 mN/m to 35 mN/m, 25 mN/m m~34mN/m, 28mN/m~36mN/m, 28mN/m~32mN/m, 31mN/m~36mN/m, 31mN/m~34mN/m, 32mN/m~37mN/m or 30mN/m~ It may be 35 mN/m. In this way, the foam sheet can improve printability and the like by having an appropriate surface tension. Surface tension may be measured using a surface tension test ink pen or the like. The surface tension measurement surface may be the surface of a skin layer.

The skin layer not only has excellent surface smoothness, but also has optimized surface area and surface energy, and has excellent printability. Specifically, printability is influenced by the surface smoothness, surface area, surface energy, etc. of the material on which the printing layer is formed, and the larger the smoothness, surface area, and surface energy, the better the printability. Here, the smoothness and surface area of the material can be affected by surface roughness, but there is a trade-off relationship between smoothness and surface area depending on the value of surface roughness. It is difficult to improve printability because smoothness and surface energy are not easy to control. However, in the present invention, the printability of the container can be significantly improved by optimizing the centerline surface roughness (Ra) and surface tension of the skin layer provided on the outermost side of the polyester foam sheet.

The crystallinity of the foam layer may be 1% to 20%, specifically 1% to 18%, 1% to 15%, 1% to 12%, 1% to 10%, 1%. ~8%, 1%~6%, 1%~4%, 1%~2%, 2%~20%, 4%~20%, 6%~20%, 8%~20%, 10%~20 %, 12% to 20%, or 15% to 20%.

The degree of crystallinity may be calculated by the following formula after measuring the enthalpy of fusion at the melting temperature and the enthalpy of crystallization at the cooling crystallization temperature using a differential scanning calorimeter (DSC).

ΔHm means enthalpy of fusion, ΔHc means enthalpy of crystallization, and ΔHm means standard enthalpy of fusion (140 J/g).

As an example, the foam layer may have a low crystallinity of 10% or less when the container is used to hold cold and hot beverages, and more than 10% when the container is used to hold hot beverages. may have a crystallinity of 15% or more.

The average cell density of the foam layer may be 100 cells/cm ² to 25,000 cells/cm ² , specifically 100 to 20,000 cells/cm ² , 100 to 15,000 cells/cm ² , 100 to 25,000 cells/cm 2 10,000 cells/cm ² , 100-5,000 cells/cm ² , 100-1,000 cells/cm 2 , 100-500 cells/cm ² , 100-400 cells/cm ² , 100-350 cells/ ^{cm 2 ,} 100-30 0cells/ cm ² , 100-250 cells/cm ² , 100-200 cells/cm ² or 160-350 cells/cm ² . The cell density may be determined by counting the number of cells within a certain unit area using a scanning electron microscope (SEM) image, and converting the number to cm ³ .

The average thickness of the foam layer is 0.5-3 mm, 0.6-2 mm, 0.7-1.5 mm, 0.8-1.2 mm, 0.9-1.1 mm or 1-1.5 mm. There may be. The average thickness of the skin layer is 0.01-1 mm, 0.02-0.8 mm, 0.03-0.6 mm, 0.04-0.4 mm, 0.05-0.3 mm, 0.06- It may be 0.2 mm, 0.07-0.15 mm, 0.08-0.12 mm or 0.05-0.1 mm.

The skin layer may be placed on the outside of the container and the foam layer may be placed on the inside of the container. The polyester foam sheet may further include a printing layer on the skin layer. The printing layer may be formed on the entire surface or a portion of the skin layer. The printed layer may be formed by printing a normal ink composition, or a sheet-like printed layer may be attached to the skin layer. The average thickness of the printing layer may be 0.01 to 5 μm, specifically 0.01 to 4.5 μm, 0.01 to 3 μm, 0.01 to 2 μm, 0.1 to 1 μm, It may be 0.1-0.5 μm, 1-5 μm, 1-3 μm, 2-4 μm or 0.1-0.2 μm.

Conventional containers have poor printability and the hue changes due to heat processes such as press molding that are performed when forming containers, making it difficult to use four or more different inks. The inventive container not only has improved printability on the outer surface (skin layer), but also because it is produced by cutting and joining already printed foam sheets, minimizing thermal exposure of the printed layer. Specifically, as described above, there is an advantage that it is possible to print a desired image using five or more hues.

According to a second embodiment of the invention, the polyester foam sheet may be composed of a single layer, and the polyester foam sheet may be a heat-treated foam sheet. After manufacturing the foam sheet, heat treating the foam sheet before cutting the foam sheet can increase the crystallinity of the foam sheet, and as the crystallinity increases, not only the insulation property but also the heat resistance properties (dimensional change rate).

The heat-treated polyester foam sheet may have high crystallinity, and specifically, the crystallinity of the heat-treated polyester foam sheet is 10% to 30%, 12% to 30%, 15% to 30%. %, 18% to 30%, 21% to 30%, 12% to 21%, 15% to 21% or 18% to 21%. If the degree of crystallinity is too low, heat insulation can be ensured to some extent, but heat resistance (dimensional change rate) may decrease.

The average cell density of the polyester foam sheet according to the second embodiment may be 100 cells/cm ² to 25,000 cells/cm ² , specifically 150 to 20,000 cells/cm ² , 200 to 15 cells/cm 2 , 000 cells/cm ^{2 ,} 250-10,000 cells/cm ² , 300-5,000 cells/cm 2 , 310-1,000 cells/cm ² , 320-800 cells/cm ² , 330-600 cells/cm ² , 340-50 0cells/ cm ² or 350-460 cells/cm ² . As cell density increases, crystallinity may increase.

It is also possible to combine the configuration of the first embodiment and the configuration of the second embodiment. That is, the foam sheet may have a multi-layer structure of a foam layer and a skin layer, and the multi-layer structure foam sheet may be heat-treated.

By having such a configuration, the present invention can not only prevent container deformation from stacked loads and/or external impact, but also suppress container deformation due to temperature changes, and improve the heat resistance and heat insulation of the container. The effect can be increased.

As an example, the container is less deformed due to temperature changes and can satisfy the condition of Equation 2 below.

In number 2,
V ₀ is the volume of the container (mm ³ ) after 3 hours of exposure to -10°C;
V ₁ is the volume of the container (mm ³ ) after exposure to 110° C. for 3 hours.

Specifically, Equation 2 means the dimensional change rate when the container is exposed to −10° C. for 3 hours and when the container is exposed to 110° C. for 3 hours. Volume means a value calculated by multiplying the width of the bottom of the container by the length of the sides of the main body. The container of the present invention has a dimensional change rate ((V ₁ - V ₀ )/V ₀ ×100) according to equation 2 in the range of 0.01 to 5%, 0.01 to 3%, or 0.01 to 1%. There may be. The dimensional change rate of the container between high and cold temperatures of 5% or less means that the container has excellent heat resistance even in sudden temperature changes, and there is almost no deformation of the container shape.

As another example, the container may be less deformed due to temperature changes and may have a volume change rate of 5% or less when evaluating the volume change before and after being left in an oven at 100° C. for 3 minutes. In particular, after the container according to the second embodiment is left in an oven at 100° C. for 3 minutes, the volume change rate of the container may be 5% or less. Here, "volume" is a value calculated by multiplying the width of the bottom part of the container by the length of the side surface of the main body, and the volume of the container is 0.01% to 5%, 0.5% to 5%, 0.5% to 4%, 0.5% to 3%, 0.5% to 2%, 0.5% to 1%, 1% to 4%, 2% to 4%, 3% to It may have a volume change rate of 5% or 3.5% to 5%. A container volume change rate of 5% or less at high temperature means that the container has excellent heat resistance, and there is almost no deformation of the container shape even at high temperatures.

The container according to the present invention is not only economical, environmentally friendly and harmless to the human body, but also allows for the production of deep containers. Further, the container according to the present invention can be easily printed on the outer surface and has excellent processability. In addition, the container according to the present invention has excellent heat resistance, heat insulation, etc., and can hold hot and/or cold contents for a long time without temperature change, so it can be usefully used as a container for food and beverages. Good too.

Since the container of the present invention has a main body and a bottom that are individually cut and joined together like a disposable cup, it can be easily manufactured even with a foam sheet with a high degree of crystallinity, and can be manufactured using conventional press molding. Compared to containers manufactured under high temperature and/or pressurized conditions, the foam sheet does not stretch and the average thickness ratio between the body and the bottom is high, making it suitable for use as containers for hot and/or cold beverages. May be usefully used.

[Container manufacturing method]
The method for manufacturing a container according to the present invention may include the steps of separating and cutting a polyester foam sheet into the shapes of a main body and a bottom, and joining the main body and the bottom.

A polyester foam sheet may be manufactured using a polyester resin composition. Specifically, the polyester resin is obtained by reacting a dicarboxylic acid component with a glycol component or by reacting a hydroxycarboxylic acid component. As the dicarboxylic acid component, one or more selected from the group consisting of terephthalic acid, naphthalene dicarboxylic acid, and adipic acid may be used. As the glycol component, one or more selected from the group consisting of ethylene glycol, butylene glycol, and 2-methyl-1,3-propanediol may be used. Further, as the hydroxycarboxylic acid component, one or more types selected from the group consisting of lactic acid and glycolic acid may be used. Preferably, polyethylene terephthalate (PET) obtained by reacting terephthalic acid and ethylene glycol may be used.

The polyester resin may be introduced in the form of pellets, granules, beads, chips, powder, etc., and in some cases may be introduced in a molten state. For example, the polyester resin may be introduced into an extruder in the form of chips to be extruded and foamed, and in this case, the resin chips may be melted at a temperature of 260 to 300°C. .

Additionally, in order to functionalize the foam sheet, various forms of additives may optionally be introduced into the fluid connection line when the polyester resin extruder is introduced, or may be introduced during the foaming process. Specifically, additives may impart barrier performance, hydrophilic function, waterproof function, etc. to the foam sheet, as well as thickeners, surfactants, hydrophilic agents, heat stabilizers, waterproofing agents, and cell size expansion agents. It may also contain one or more selected from the group consisting of agents, infrared attenuators, plasticizers, fire protection chemicals, pigments, elastic polymers, extrusion aids, antioxidants, nucleating agents, anti-revolution agents, and UV absorbers.

For example, the foamed sheet of the present invention may be manufactured using one or more of a thickener, a nucleating agent, a heat stabilizer, and a foaming agent in addition to the polyester resin, and may also include the above-mentioned functional additives. One or more of these may be further used.

The thickener is added to control the melt viscosity of the foam composition, and for example, pyromellitic dianhydride (PMDA) may be used. The content of the thickener may be 0.1 to 5 parts by weight, 0.3 to 3 parts by weight, or 0.5 to 2 parts by weight based on 100 parts by weight of the resin.

Nucleating agents are added to control cell density, and include, for example, talc, mica, silica, diatomaceous earth, alumina, titanium oxide, zinc oxide, magnesium oxide, magnesium hydroxide, aluminum hydroxide, calcium hydroxide, Potassium carbonate, calcium carbonate, magnesium carbonate, potassium sulfate, barium sulfate, sodium bicarbonate, glass beads, etc. may also be used. The content of the nucleating agent may be 0.1 to 5 parts by weight, 0.3 to 3 parts by weight, or 0.5 to 2 parts by weight based on 100 parts by weight of the resin.

As the heat stabilizer, organic or inorganic phosphorus compounds may be used, specifically phosphoric acid, alkyl phosphates, aryl phosphates, such as triphenyl phosphate. The content of the heat stabilizer may be 0.01 to 5 parts by weight, 0.03 to 3 parts by weight, or 0.05 to 1 part by weight based on 100 parts by weight of the resin.

The foaming agent is added to foam the composition and control the density of the foam sheet, and includes, for example, gases such as N2 _, CO2 _, and chlorofluorocarbons, butane, pentane, neopentane, hexane, isohexane, heptane, Physical blowing agents such as isoheptane and methyl chloride, chemical blowing agents such as azodicarbonamide-based compounds, P,P'-oxybis(benzenesulfonylhydrazide)-based compounds, N,N'-dinitrosopentamethylenetetramine-based compounds may be used. The content of the blowing agent may be 0.1 to 10 parts by weight, 1 to 8 parts by weight, or 3 to 7 parts by weight based on 100 parts by weight of the resin.

Extrusion may be performed using various types of extruders. The foaming step may normally be performed by bead foaming or extrusion foaming, but extrusion foaming is preferred in the present invention. In extrusion foaming, the resin mixture is continuously extruded and foamed, which simplifies the process steps and allows for mass production.When foaming beads, it is possible to prevent cracks and granular breakage phenomena between the beads, so it is more efficient. It can realize excellent bending strength and compressive strength.

In the case of the main body, the foam sheet may be directly produced in the shape of the main body. For example, if the main body is cylindrical and tubular, the cylindrical main body may be directly produced by using an annular nozzle during the production of the polyester foam sheet. good. Alternatively, after manufacturing the foam sheet, it may be cut into body-forming members, and then both ends of the body-forming members may be joined to form the body. Specifically, the main body may be manufactured by cutting a polyester foam sheet into a rectangular or fan shape, and then joining both ends thereof. The foam sheet may be cut using a normal cutting machine. Bonding of the foam sheets may be performed by applying heat or ultrasound, or by using a low melting point polyester resin adhesive or an adhesive sheet.

The bottom may be made or cut to have the same shape as the inside of the lower end of the body thus produced. For example, if the body is made cylindrical or truncated, the bottom may be made or cut into a circle (disc). The size of the bottom may be the same as or smaller than the inside of the lower end of the body.

When joining the main body and the bottom, the bottom may be pushed up and inserted into the inner lower end of the main body, and then joined. At this time, heat or ultrasonic waves may be applied to the area where the inserted bottom part contacts the inside of the main body, or a low melting point polyester resin adhesive or an adhesive sheet may be used to bond the bottom part to the lower end of the main body. Specifically, the bonding process is performed by applying direct heat or irradiating ultrasonic waves to the area between the thicknesswise side surface of the bottom that abuts the main body and/or the inner surface of the bottom end of the main body that abuts the bottom. Alternatively, an adhesive containing a low melting point polyester resin may be applied to the area, or an adhesive sheet may be laminated and then heat may be applied to bond the area.

The temperature of the heat applied during bonding may be 100 to 400°C, specifically 100 to 350°C, 100 to 300°C, 100 to 250°C, 100 to 200°C, 100 to 150°C, 100°C -130°C or 120-140°C. For example, if an adhesive or adhesive sheet is not used, heat of 200 to 330°C can be applied, and if an adhesive or adhesive sheet is used, a temperature of 100 to 200°C can be applied so that the low melting point polyester resin exhibits adhesive properties. ℃ heat can be applied.

According to the first embodiment of the present invention, when manufacturing a polyester foam sheet, after forming a foam layer, the surface of the foam layer may be cooled to form a skin layer. Specifically, when manufacturing the foam sheet, the skin layer may be formed by rapidly cooling the surface of the foam layer by adjusting the temperature of a mandrel, which is a cooling device. The temperature of the mandrel may be -30 to 0°C, -25 to -5°C, or -20 to -10°C.

According to a first embodiment of the invention, a printing layer may be formed on the skin layer. For example, a printed layer may be formed using an ink composition by a normal printing method. The printed layer may be formed during manufacture of the foam sheet, before or after cutting, or before or after bonding. For example, a pattern and/or pattern may be applied using a conventional printing method using four or more inks having different hues. As the printing method, inkjet printing, gravure printing, screen printing, offset printing, rotary printing, flexo printing, etc. may be used.

According to a second embodiment of the present invention, the method may further include heat treating the polyester foam sheet before cutting. The heat treatment temperature may be 150-300°C, 160-270°C, 170-250°C, 180-230°C or 190-210°C. The heat treatment time may be 10-100 seconds, 15-80 seconds or 20-60 seconds. The degree of crystallinity of the foam sheet may increase as the heat treatment temperature and heat treatment time increase.

Hereinafter, the present invention will be explained in more detail with reference to Examples, Comparative Examples, and Experimental Examples.

[Examples 1-1 to 1-5]
After drying 100 parts by weight of polyethylene terephthalate (PET) resin at 130°C to remove water, add 1 part by weight of pyromellitic dianhydride based on the PET resin from which water was removed and 100 parts by weight of PET resin to an extruder. , 1 part by weight of talc, and 0.1 part by weight of Irganox (IRG1010) were mixed and heated to 280°C to prepare a resin melt. Next, 5 parts by weight of butane gas as a foaming agent is added to the extruder based on 100 parts by weight of PET resin, and extrusion is carried out to produce a PET foam sheet. A skin layer in which the surface of the foam layer was rapidly cooled was formed by adjusting the temperature as shown in Table 1 below. The cell density, cell size, and average thickness of the foamed sheet thus manufactured are shown in Table 1 below.

Next, the produced PET foam sheet was cut into fan shapes (large arc: 22.2 cm, small arc: 15.7 cm, side length: 7.5 cm) and circles (diameter: 5 cm). After that, a low melting point polyester adhesive sheet with a thickness of about 5 mm was pasted on the outside of one end of the fan-shaped foam sheet and the inside of the other end, and after wrapping both ends and stacking them, heat was applied to 130℃. The main body was fabricated. After applying a low melting point polyester adhesive to a thickness of about 2±0.1 mm on the inside of the lower end (small arc side) of the fabricated main body, and pushing the previously cut circular foam sheet into position, A disposable cup-shaped container was manufactured by applying heat at 130° C. to join the bottom to the main body. At this time, the height (H) of the side surface of the container was 7 cm, and the diameter (D) of the bottom surface was 5 cm (H/D=1.4).

[Comparative example 1-1]
I bought a commercially available paper cup. At this time, the height (H) of the side surface and the diameter (D) of the bottom surface of the paper cup were the same as those of the container of Example 1-1, and the average thickness of the paper cup was 1±0.1 mm.

[Comparative example 1-2]
It was carried out in the same manner as in Example 1-1, except that a commercially available polypropylene film (PP rigid film, average thickness: 1.0 ± 0.05 mm) was purchased and used instead of the PET foam sheet. Manufactured a container. At this time, the cell density of the polypropylene film was 900 cells/cm ² .

[Comparative example 1-3]
Example 1-1 except that the cell density and average thickness of the foam layer provided in the PET foam sheet, the cell size and average thickness of the skin layer, and the temperature of the mandrel were controlled as shown in Table 2 below. The same method was followed to produce containers.

[Comparative example 1-4]
After producing a foam sheet in the same manner as in Example 1-1, the PET foam sheet was introduced into a press molding machine without cutting, joining, or heat treatment, and the surface temperature of the foam sheet was 160 ° C. The temperature of the male mold (Plug) was set to 60°C, and the temperature of the female mold (Mold) was set to 120°C, and press molding was performed for 10 seconds to manufacture a container.

[Experiment example 1]
In order to confirm the performance of the containers according to the present invention, the following experiments were conducted using the containers manufactured in Examples 1-1 to 1-5 and Comparative Examples 1-1 to 1-4, and the results are summarized below. It is shown in Table 3.

<Measurement of center line surface roughness>
The centerline surface roughness of the containers manufactured in Examples and Comparative Examples was measured according to KS B 0161.

<Measurement of surface tension>
The surface tension of the outer surface of the containers manufactured in Examples and Comparative Examples was measured using a surface tension test ink pen (Dyne pen, Arotes). At this time, the ink pen should be a product with a surface tension of 30 to 60 mN/m, and after painting the outer surface of the container with the ink pen, the dyne of the ink pen should be applied to the outer surface of the container if there is no stain on the surface. The surface tension was determined.

<Evaluation of insulation>
Water at 100° C. was poured into each container prepared in Examples and Comparative Examples to make up 70% by volume of the container accommodating portion, and the containers were left for 3 minutes at room temperature (20° C.) and at normal temperature (1 atm). Thereafter, the temperature of the water in the container and the temperature of the outer surface of the container body were measured, and the deviation between the measured temperatures was calculated.

As shown in Table 3, it can be seen that the containers according to the present invention have excellent printability and excellent heat resistance and/or heat retention.

Specifically, the containers manufactured in the examples have a low centerline surface roughness (R a ) of less than 2.5 μm and a high surface tension of more than 28 mN/m, whereas the beverage containers of the comparative examples have a low centerline surface roughness (R _a ) of less than 2.5 μm and a high surface tension of more than 28 mN/m. It was confirmed that both the surface roughness (R _a ) and high surface tension were not satisfied.

In addition, when the beverage containers manufactured in the examples are filled with water at 100 degrees Celsius, the temperature difference between the inside and outside of the container is 10 degrees Celsius or more, whereas the beverage containers manufactured in the comparative examples are It showed a low temperature deviation. This means that the containers manufactured in Examples had excellent heat insulation properties, and the temperature difference between the inside and outside of the container was kept relatively large.

According to the examples, as the cell density of the foam layer decreased, the heat insulation increased, and as the cell size of the skin layer decreased, the surface roughness decreased and the surface tension increased.

In the case of Comparative Example 1-1, the surface tension was large and the heat insulation properties were decreased. In the case of Comparative Example 1-2, the surface tension was low and the heat insulation property was very low. In the case of Comparative Example 1-3, the cell size of the skin layer was too large, the surface roughness was too large, and the surface tension was too small. In the case of Comparative Example 1-4, the surface tension was low and the heat insulation properties were decreased due to press molding.

These results show that the container according to the present invention not only has excellent thermal properties such as heat insulation, but also has excellent printability.

[Examples 2-1 to 2-6]
After drying 100 parts by weight of polyethylene terephthalate (PET) resin at 130°C to remove moisture, the PET resin from which the moisture was removed and 1 weight of pyromellitic dianhydride based on 100 parts by weight of this PET resin were added to an extruder. 1 part by weight of talc, and 0.1 part by weight of Irganox (IRG 1010) were mixed and heated to 280°C to prepare a resin melt. Next, 5 parts by weight of butane gas as a foaming agent was introduced into the extruder based on 100 parts by weight of PET resin, and extrusion foaming was performed to produce a PET foam sheet. The cell density, average thickness, crystallinity, heat treatment time, and ratio of the thickness of the main body and the bottom of the produced foamed sheet are shown in Table 4 below.

Next, the manufactured PET foam sheet was heat-treated in a 200°C chamber for the time shown in Table 4 below, and the heat-treated foam sheet was shaped like a fan (large arc: 22.2 cm, small arc: 15.7 cm, side It was cut into circles (length: 7.5 cm) and circles (diameter: 5 cm). After that, a low melting point polyester adhesive sheet with a thickness of about 5 mm was pasted on the outside of one end of the fan-shaped foam sheet and the inside of the other end, and after wrapping both ends and stacking them, heat was applied to 130℃. The main body was fabricated. After applying a low melting point polyester adhesive to a thickness of about 2±0.1 mm on the inside of the lower end (small arc side) of the fabricated main body, and pushing the previously cut circular foam sheet into position, A disposable cup-shaped container was manufactured by applying heat at 130° C. to join the bottom to the main body. At this time, the height (H) of the side surface of the container was 7 cm, and the diameter (D) of the bottom surface was 5 cm (H/D=1.4).

[Comparative example 2-1]
I bought a commercially available paper cup. At this time, the height (H) of the side surface and the diameter (D) of the bottom surface of the paper cup were the same as those of the container of Example 2-1, and the average thickness of the paper cup was 1±0.1 mm.

[Comparative example 2-2]
It was carried out in the same manner as in Example 2-1, except that a commercially available polypropylene film (PP rigid film, average thickness: 0.7 ± 0.05 mm) was purchased and used instead of the PET foam sheet. Manufactured a container. At this time, the cell density of the polypropylene film was 900 cells/cm ² . The ratio of body to bottom thickness was 1.0.

[Comparative example 2-3]
A PET foam sheet (cell density: 350 cells/cm ³ , average thickness: 1.5 mm, crystallinity: 4%) under the same conditions as in Example 2-1 was prepared. Next, the prepared PET foam sheet was taken into a press molding machine without any separate heat treatment so that the surface temperature of the foam sheet became 160°C, and then the temperature of the male mold (Plug) was changed to 60°C, and the temperature of the female mold was set to 60°C. The temperature of the mold was set to 120° C., and press molding was performed for 10 seconds to produce a container. The H/D of the mold is 1.0, the depth (H) of the accommodating part is 10 cm, and the diameter (D) of the opening is 10 cm. The bottom thickness ratio was 0.5.

[Comparative Examples 2-4 and 2-5]
A container was prepared in the same manner as in Example 2-1, except that the PET foam sheet was not heat-treated separately and the cell density, average thickness, and crystallinity of the foam sheet were adjusted as shown in Table 5 below. was manufactured.

[Experiment example 2]
In order to confirm the thermal performance of the container according to the present invention, the following experiment was conducted and the results are shown in Table 6 below.

<Evaluation of insulation>
Water at 100° C. was poured into each container prepared in Examples and Comparative Examples to make up 70% by volume of the container accommodating portion, and the containers were left for 3 minutes at room temperature (20° C.) and at normal temperature (1 atm). Thereafter, the temperature of the water in the container and the temperature of the outer surface of the container body were measured, and the deviation between the measured temperatures was calculated.

<Evaluation of heat resistance>
The diameter and height of the top and bottom surfaces of each container prepared in Examples and Comparative Examples were measured, and the volume of each container was calculated from the measured diameter and height. Next, each container was heat-treated by leaving it in an oven at 100°C for 3 minutes, and after cooling it again to room temperature, the volume of the container was calculated using the same method as described above, and the rate of change in volume of the container before and after heat treatment was calculated. derived.

As shown in Table 6, it can be seen that the containers according to the present invention have excellent heat insulation properties and heat resistance.

Specifically, it was shown that the temperature of the outer surface of the container manufactured in the example was more than 10°C different from the water temperature even after 3 minutes had passed after filling with 100°C water. The containers made in the comparative example, made of paper or polypropylene film, or made by thermoforming, showed a low temperature deviation of less than 10°C. This means that the containers manufactured in Examples have excellent heat insulation properties, and the temperature difference between the inside and outside of the container is maintained relatively large.

Furthermore, it was confirmed that the volume change rate of the containers manufactured in Examples was less than 5% even when left under high temperature conditions of 100°C. However, it was confirmed that the container of the comparative example manufactured using the foam sheet had a volume change rate of 8% or more. This means that since the containers of Examples have excellent heat resistance, there is almost no deformation of the shape of the containers even with rapid temperature changes.

According to the examples, the crystallinity increased as the cell density increased, the crystallinity increased as the heat treatment time increased, and the heat resistance improved as the crystallinity increased.

In the case of Comparative Examples 2-1 and 2-2, the degree of crystallinity was 0, and the heat resistance was good, but the heat insulation property was low. In the case of Comparative Example 2-3, the degree of crystallinity was low because there was no heat treatment, the heat insulation properties were also decreased due to press molding, and the heat resistance was decreased due to the low degree of crystallinity. In the case of Comparative Examples 2-4 and 2-5, the degree of crystallinity was low because no heat treatment was performed, and the heat insulation properties were good, but the heat resistance was decreased due to the low degree of crystallinity.

These results show that the container according to the present invention has excellent heat resistance and/or heat insulation (ie, heat retention).

Claims (13)

A main body including a polyester foam sheet,
A container comprising a bottom portion located at the lower end of the main body and comprising a polyester foam sheet, the container comprising:
The container is not manufactured in one piece by press molding of a foam sheet;
The container has a main body and a bottom that are made separately and are joined to each other to form a sealed structure,
Under the conditions of 23 ± 5 ° C and 1 ± 0.2 atm, after 3 minutes have passed after filling the container with 100 ° C water, the temperature difference between the outer surface of the main body and the water inside the main body is 10 ° C or more,
The main body and bottom are joined by adhesive or adhesive sheet,
The adhesive or adhesive sheet contains a low melting point polyester resin,
The low melting point polyester resin has the following chemical formulas 1 and 2:

[In Chemical Formulas 1 and 2, m and n represent the molar fraction of the repeating unit contained in the low melting point polyester resin, and based on m + n = 1, n is 0.05 to 0.5]
It contains a repeating unit represented by, and has a softening point of 100°C to 130°C or a glass transition temperature of 50°C to 80°C,
The height (H) of the side surface of the main body is 5 cm to 20 cm,
The ratio (H/D) of the height (H) of the side surface of the main body to the diameter (D) of the bottom part is 0.5 or more,
The ratio of the average thickness of the body and the bottom (body/bottom) is 0.8 or more,
The surface tension of the polyester foam sheet is 25 mN/m or more,
A container in which the polyester foam sheet has an average cell density of 100 cells/cm ² to 25,000 cells/cm ² . Polyesters include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polyethylene naphthalate (PEN), polyethylene adipate (PEA), polylactic acid (PLA), and polyglycolic acid (PGA). The container according to claim 1, which is one or more types selected from among them. The container is a beverage container,
The container according to claim 1, wherein the polyester foam sheet has an average thickness of 0.5 mm to 3 mm. The polyester foam sheet includes a foam layer and a skin layer,
A container according to claim 1, wherein the centerline surface roughness (R _a ) of the skin layer is between 0.1 μm and 2.5 μm. The crystallinity of the foam layer is 1% to 20%,
The average cell density of the foam layer is 100 cells/cm ² to 25,000 cells/cm ² ,
5. The container according to claim 4, wherein the skin layer has an average cell size of 100 μm or less. 5. The container of claim 4, wherein the polyester foam sheet further comprises a printed layer on the skin layer. Polyester foam sheet is composed of a single layer,
2. The container of claim 1, wherein the polyester foam sheet is a heat-treated foam sheet. The crystallinity of the heat- treated polyester foam sheet is 10% to 30%,
The container according to claim 7, wherein the volume change rate of the container is 5% or less after the container is left in an oven at 100° C. for 3 minutes. A method for manufacturing a container according to claim 1, comprising:
Separating or cutting the polyester foam sheet into body and bottom shapes;
A method of manufacturing a container, comprising: joining a body and a bottom. After applying an adhesive containing a low melting point polyester resin to the inside of the lower end of the main body, the sides in the thickness direction of the bottom, or both, or laminating an adhesive sheet,
After pushing up the bottom part and inserting it into the inner lower end of the main body,
10. The method for manufacturing a container according to claim 9, wherein a temperature of 100° C. to 400° C. is applied to a joining portion between the inserted bottom and the main body. 10. The method for manufacturing a container according to claim 9, wherein when manufacturing a polyester foam sheet, after forming a foam layer, the surface of the foam layer is cooled to form a skin layer. The method for manufacturing a container according to claim 11, wherein a printing layer is formed on the skin layer. The method for manufacturing a container according to claim 9, further comprising the step of heat treating the polyester foam sheet at 150° C. to 300° C. for 10 seconds to 100 seconds before cutting.