JP7125496B2 - Composite sheet with excellent workability and method for manufacturing packaging container containing the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to a composite sheet with excellent workability and a method for manufacturing a packaging container including the same.

Products used in ordinary food packaging containers are divided into foaming type and non-foaming type. As a foam type food packaging container, a product obtained by mixing polystyrene with a foaming gas and extruding it is used. It is advantageous, and has the advantages of high heat insulation and price competitiveness. On the other hand, foaming products have the disadvantage that harmful substances are detected at high temperatures.

Cup noodle containers are the most commonly used disposable heat-resistant containers, but we used polystyrene foam containers before. However, in the case of polystyrene foam containers, it has become an issue that harmful substances are detected at high temperatures, so paper containers are being used instead, but there is a disadvantage in that they are expensive.

On the other hand, as life becomes more and more convenient in modern society, the use of disposable items is increasing, and the demand for delivery food and simple cooking products is increasing as the number of single-person households increases. As a result, the demand for food packaging containers is increasing, and consumer needs are growing for new container materials that are safe from harmful substances and are given functions according to their intended use.

In relation to this, the food packaging container industry is researching and developing a food packaging container that has convenience, safety, ecological performance and price competitiveness. We have developed resin foams and packaging containers containing them. Since the packaging container is manufactured using a polyester resin as a resin foam, it is environmentally friendly, lightweight, and has high strength, and has excellent durability against temperature changes. .

On the other hand, in some cases, the packaging container includes a polyester film on one surface of the resin foam in order to form a printed layer and the like, and the printed layer is formed by printing on the outer surface of the polyester film. However, since a stretched film that has undergone stretching treatment is used as the polyester film, there is a problem that the molded sheet is broken during the molding process of the packaging container, resulting in deterioration of workability.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems, and to provide a method of manufacturing a composite sheet having excellent processability and a packaging container including the same.

In order to achieve the above object, the present invention provides a structure in which a polyester foam sheet having an average thickness of 0.9 to 10 mm and a polyester film having an average thickness of 15 to 200 μm formed on one or both sides of the foam sheet are laminated. The polyester film is a non-stretched film, and after being treated at a temperature of 200° C. for 30 seconds, the composite sheet has an elongation of 200-600%.

Also, the present invention provides a step of placing the composite sheet between a female mold and a male mold of a molding device; and; wherein, in the molding step, the surface temperature of the mold of the female mold is set to 40 to 200°C.

The composite sheet according to the present invention can provide a composite sheet having an elongation of 200 to 600% at a temperature of 200° C. by including an unstretched polyester film on one or both sides of the polyester foam sheet.

In addition, when manufacturing a packaging container using the composite sheet, there is an advantage of excellent workability.

FIG. 1 is a cross-sectional view of a composite sheet according to the invention.
FIG. 2 is a diagram sequentially showing a method of manufacturing a packaging container according to the present invention.
FIG. 3 is a diagram showing a packaging container manufactured by the method for manufacturing a packaging container according to the present invention.

Since the present invention can be modified in various ways and has various embodiments, specific embodiments will be illustrated in the drawings and will be described in detail in the detailed description.

However, this is not intended to limit the invention to any particular embodiment, but should be understood to include all modifications, equivalents or alternatives falling within the spirit and scope of the invention. not.

In the present invention, terms such as "including" or "having" are intended to specify the presence of the features, figures, steps, acts, components, parts, or combinations thereof set forth in the specification. without precluding the possibility of the presence or addition of one or more other features, figures, steps, acts, components, parts or combinations thereof.

Therefore, the configuration shown in the embodiment described in this specification is merely one of the most preferable embodiments of the present invention, and does not represent the technical idea of the present invention. There may be various equivalents and variations which may be substituted for them at the time.

An "unstretched film" in the present invention is a film that has not been stretched, and specifically means a film that is not stretched in any direction other than at a mechanical extrusion rate to impart orientation without being stretched. Meanwhile, the 'film' may have a broader meaning including not only the form of film commonly used in the art but also the form of sheet.

In the present invention, "elongation" means the ratio of _elongation of _a material during a material tensile test. The ratio δ=(I ₁ −I ₀ )/I ₀ ×100 (%). In particular, the composite sheet according to the present invention can have an elongation of 200-600% after being treated at a temperature of 200° C. for 30 seconds. The elongation here means the total elongation of the composite sheet, not the individual elongation of the foamed sheet or unstretched film.

In the present invention, the "low melting point polyester powder" is a kind of adhesive powder for laminating the foamed sheet of the composite sheet and the polyester film, and as a copolyester powder it has a low melting point of 250 ° C. or less, sometimes about 120 to 130 ° C. (or softening point). The melting point and softening point can be measured using a melting point measuring device and a softening point measuring device, respectively.

TECHNICAL FIELD The present invention relates to a composite sheet with excellent workability and a method for manufacturing a packaging container including the same.

On the other hand, since the composite sheet of the present invention contains a non-stretched polyester film, the elongation rate can be increased and the composite sheet can have excellent processability during the production of packaging containers. In addition, the composite film includes a polyester foam sheet and a polyester film having the same components, and has the advantage of being convenient for recycling separation.

The composite sheet according to the present invention will now be described in detail.
FIG. 1 is a cross-sectional view of a composite sheet according to the invention. Referring to FIG. 1, the composite sheet 100 of the present invention is laminated with a polyester foam sheet 101 having an average thickness of 0.9 to 10 mm; and a polyester film 102 having an average thickness of 15 to 200 μm formed on one or both sides of the foam sheet. The polyester film 102 is a non-stretched film, and the elongation of the composite sheet 100 is 200-600% after the composite sheet 100 is treated at a temperature of 200° C. for 30 seconds. The average thickness may be, for example, a value obtained by averaging the thickness of the sheet or film at 10 points using a thickness gauge.

The composite sheet 100 of the present invention includes the polyester film 102 on one or both sides of the polyester foam sheet 101, so that the surface smoothness can be improved, the printability is excellent, and the beautiful appearance can be realized after processing. There is an effect that can be done. For example, when manufacturing food packaging containers, the polyester film 102 can be printed to form the exterior surface.

The polyester film 102 is not a foam sheet but a polyester sheet or non-stretched film. In particular, the polyester film 102 is characterized by being a non-stretched film, which has the advantage of excellent workability when manufacturing packaging containers. Specifically, if the stretched film is used to manufacture the packaging container, the stretched film is already in a stretched state, so it is not easy to stretch even if heat is applied. However, since the composite sheet of the present invention uses a non-stretched film and has excellent high-temperature elongation, it has the advantage of being excellent in workability. Meanwhile, the packaging container means a food packaging container, and may be a disposable food packaging container.

In addition, since the composite sheet 100 of the present invention includes the polyester foam sheet 101 and the polyester film 102 of the same component, it has the advantage of being convenient for recycling separation.

First, the polyester foam sheet 101 and the polyester film 102 of the present invention are polyester resin, and the polyester resin may contain repeating units derived from an acid component and a diol component. Specifically, the polyester resin may be one or more selected from the group consisting of aromatic and aliphatic polyester resins synthesized from dicarboxylic acid components and glycol components or hydroxycarboxylic acids.

Examples of the polyester resin include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polylactic acid (PLA), polyglycolic acid (PGA), and polyethylene adipate. , PEA), polyhydroxyalkanoate (PHA), polytrimethylene terephthalate (PTT) and polyethylene naphthalate (PEN). Specifically, polyethylene terephthalate (PET) may be used in the present invention.

That is, the polyester foam sheet 101 may be a polyethylene terephthalate (PET) foam sheet, and the polyester film 102 may be a polyethylene terephthalate (PET) film.

The composite sheet 100 includes a polyester foam sheet 101 and a polyester film 102 of the same component, and has the advantage of being convenient for recycling separation. Meanwhile, the polyester foam sheet 101 and the polyester film 102 may be laminated with a low melting point polyester powder (not shown), a solvent-based adhesive, or the like. In the composite film 100 of the present invention, not only the polyester foam sheet 101 and the polyester film 102 but also the adhesive components are made of the same polyester resin, so that the adhesive strength between the foam sheet and the film can be increased. has the advantage of being convenient during recycle separation. The low-melting powder melts completely or partially during the lamination process and then cures to bond the two layers together. It is possible to maintain the bonding state of the two layers.

Also, the density of the foamed sheet (KS M ISO 845) can average from 50 to 700 kg/m ³ . Specifically, the foam sheet has an average density of 50 to 500 kg/m ³ , 50 to 300 kg/m ³ , 50 to 100 kg/m ³ , 100 to 700 kg/m ³ , 200 to 700 kg/m ³ , 300 to 700 kg/m 3 . m ³ , 500-700 kg/m ³ , 300-600 kg/m ³ or 400-500 kg/m ³ .

On the other hand, when the density of the foamed sheet is extremely low, there are many air bubbles in the foamed sheet, so the foamed sheet may be broken during processing of the packaging container, and H/D≧0.3 (H: depth of the container, D: The diameter of the opening) cannot be easily manufactured. Alternatively, although the above H/D≧0.3 can be satisfied, it is difficult to realize a packaging container with an average thickness of 2.0 mm or less, and the thickness deviation between the bottom and the wall of the packaging container is large. As a result, the compressive strength, heat resistance, or heat shielding properties of the packaging container are low.

If the density of the foamed sheet is extremely high, the weight of the packaging container itself is so heavy that it is not suitable as a packaging container for disposable use, and there is a problem that the cost increases during the manufacturing process.

Therefore, the density of the foam sheet forming the packaging container is preferably 50 to 700 kg/m ³ on average, so that the foam sheet has a small thickness and achieves improved compressive strength, heat resistance, and heat shielding properties. can do.

In the present invention, the polyester film 102 may be an unstretched film. Here, the unstretched film is a film that has not been stretched, and specifically means a film that is not stretched or stretched without being stretched in any direction other than at a mechanical extrusion speed. On the other hand, the film may have a broader meaning including not only the film form generally used in the art but also the sheet form.

In particular, by including the polyester film 102 on one or both sides of the polyester foam sheet 101, surface smoothness can be improved, printability is excellent, and a beautiful appearance can be realized after processing. For example, when manufacturing food packaging containers, the polyester film 102 can be printed to form the exterior surface.

Such a polyester film 102 may be a non-stretched film, and the density of the non-stretched film is 1,000-1,700 kg/m ^{3 , 1,100-1,600 kg/m 3 ,} 1,200-1 , 500 kg/m ³ , 1,300-1,450 kg/m ³ , 1,350-1,400 kg/m ³ or 1,380 kg/m ³ .

The non-stretched film may have a tensile strength of 15 kg/mm ² or less. For example, the tensile strength of the unstretched film is 1 to 15 kg/mm ² , 1 to 12 kg/mm ² , 1 to 10 kg/mm ² , 1 to 8 kg/mm ² , 1 to 6 kg/mm ² , 1 to 4 kg/mm. ² , 1-2 kg/mm ² , 2-15 kg/mm ² , 4-15 kg/mm ² , 6-15 kg/mm ² , 10-15 kg/mm ² , 3-13 kg/mm ² or 5-11 kg/mm ² can be The tensile strength can be measured using a tensile strength tester under the conditions of a test piece size of 70 mm in height×25 mm in width, a test speed of 50 mm/min, and a gap size of 20 mm.

In the composite sheet 100 of the present invention, the polyester foam sheet 101 may have an average thickness of 0.9-10 mm, and the polyester film 102 may have an average thickness of 15-200 μm. For example, the polyester foam sheet 101 has an average thickness of 0.9 to 10 mm, 0.9 to 8 mm, 0.9 to 6 mm, 0.9 to 4 mm, 0.9 to 2 mm, 1 to 10 mm, 2 to 10 mm, It can range from 4-10 mm, 6-10 mm, 8-10 mm, 2-8 mm or 4-6 mm.

On the other hand, if the average thickness of the polyester foam sheet 101 is extremely thin, there may be a problem that the foam sheet 101 may be broken during the manufacture of the food container. When the average thickness of the polyester foam sheet 101 is extremely thick, even if a food container is manufactured, there is a problem that the price rises due to the extremely thick thickness, and it is difficult to manufacture a food container having a desired shape when molding the food container. I have a difficult problem.

The average thickness of the polyester film 102 is 15 to 200 μm, 15 to 150 μm, 15 to 100 μm, 15 to 80 μm, 15 to 60 μm, 15 to 50 μm, 15 to 40 μm, 40 to 200 μm, 60 to 200 μm, 80 to 200 μm. , 100-200 μm, 40-150 μm, 80-150 μm, 20-45 μm or 20-30 μm.

On the other hand, the thinner the polyester film 102, the better the moldability. However, the non-stretched polyester film 102 may be difficult to implement, and if it is too thick, the price may increase.

Meanwhile, the composite sheet 100 may be a composite sheet 100 in which a polyester foam sheet 101 and a polyester film 102 are laminated. Specifically, the composite sheet 100 may be formed by laminating a polyester film 102 on a polyester foam sheet 101 in which low melting point polyester powder or resin is dispersed or laminated on one side, or by laminating a polyester film 102 on one side. It may be formed by laminating the polyester foam sheet 101 on the polyester film 102 in which the low melting point polyester powder or resin is dispersed or laminated. Here, the method of dispersing or laminating the low-melting polyester powder or resin may include spreading, placement, coating, adhesion, vapor deposition, and the like.

Here, the low melting point polyester powder or resin is a kind of adhesive powder or adhesive resin for laminating the foamed sheet 101 and the polyester film 102 of the composite sheet 100 in the present invention. It is interposed between the polyester film 101 and the polyester film 102 and performs the function of providing adhesion between the polyester foam sheet 101 and the polyester film 102 . A low melting point polyester powder or resin means a copolyester powder or resin having a melting point (or softening point) as low as 250°C or less, sometimes as low as 120-130°C.

The low-melting-point polyester powder may include at least one resin (low-melting-point polyester resin) capable of achieving adhesion, and the resin may be formed in the form of powder. For example, the low melting point polyester powder may be in the form of powder of polyester resin having a melting point of 180-250°C or a softening point of 100-150°C.

As an example, the low melting point polyester powder or resin may have a melting point (Tm) of 180° C. to 250° C. or 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, or 195°C to 230°C, may not exist.

In addition, the softening point of the low melting point polyester powder or resin may be 100°C to 150°C, specifically 100°C to 130°C, 118°C to 128°C, 120°C to 125°C, 121°C to 124°C. °C, 124°C to 128°C or 119°C to 126°C.

In turn, the low melting point polyester powder or 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 61°C to 69°C, 60°C to 65°C, 63°C to 67°C, 61°C to 63°C, 63°C to It can be 65°C, 65°C-67°C or 62°C-67°C.

Also, the low melting point polyester powder or resin may have an intrinsic viscosity (I.V) of 0.5 to 0.75 dl/g. Specifically, the intrinsic viscosity (I.V) is 0.6 to 0.65 dl/g, 0.65 to 0.7 dl/g, 0.64 to 0.69 dl/g, 0.65 to 0.65 dl/g. 68 dl/g, 0.67-0.75 dl/g, 0.69-0.72 dl/g, 0.7-0.75 dl/g or 0.63-0.67 dl/g.

The low melting point polyester powder or resin according to the present invention may contain repeating units represented by Formula 1 and Formula 2. Through this, the melting point (Tm), softening point, and glass transition temperature (Tg) can be adjusted within the above ranges, and the resin having physical properties adjusted within the above ranges can exhibit excellent adhesiveness.

In the chemical formula 1 and chemical formula 2,
m and n represent the molar fraction of repeating units contained in the low-melting polyester powder or 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 and m is 0.5-0.95, 0.6-0.95, 0.6-0 .9, 0.65-0.85 or 0.7-0.8.

The low melting point polyester powder or resin according to the present invention may have a structure containing repeating units represented by Formulas 1 and 2. The repeating unit represented by Chemical Formula 1 represents a repeating unit of polyethylene terephthalate (PET), and the repeating unit represented by Chemical Formula 2 functions to improve tear properties of the polyester resin including the polyethylene terephthalate (PET) repeating unit. Specifically, the repeating unit represented by Formula 2 includes a methyl group (--CH ₃ ) as a side chain in the propylene chain bound to the terephthalate, and secures a space so that the main chain of the polymerized resin can rotate. This can induce an increase in the degree of freedom of the main chain and a decrease in the crystallinity of the resin, thereby reducing the melting point (Tm). This can have the same effect as conventionally using isophthalic acid (IPA) containing an asymmetric aromatic ring to reduce the melting point (Tm) of the crystalline polyester resin.

At this time, the polyester resin may include the repeating unit of Chemical Formula 1 including the ester repeating unit and the repeating unit of Chemical Formula 2 that lowers the melting point (Tm) of the resin as main repeating units. Specifically, the low-melting-point polyester resin of the present invention may contain 0.5 to 1 repeating units represented by Formulas 1 and 2 when the mole fraction of the entire resin is 1. Specifically, 0.55-1, 0.6-1, 0.7-1, 0.8-1, 0.5-0.9, 0.5-0.85, 0.5-0.7 or 0.5-1. 6 to 0.95.

In addition, the amount (n) of the repeating unit represented by Chemical Formula 2 contained in the low-melting polyester powder or resin is 0.05 when the total fraction including the repeating unit represented by Chemical Formula 1 is 1 (m+n=1). ~0.5, specifically 0.05-0.4, 0.1-0.4, 0.15-0.35 or 0.2-0.3.

As an example, the average weight per unit area of the low melting point polyester powder or resin may range from 10 to 50 g/m ² , specifically, the polyester resin powder may have an average weight per unit area of 10 to 40 g/m 2 . ² , 10-30 g/m ² , 10-20 g/m ² , 20-50 g/m ² , 30-50 g/m ² , 40-50 g/m ² or 20-40 g/m ² . According to the present invention, by controlling the average weight per unit area of the low-melting polyester powder within the above range, excessive weight increase of the composite sheet can be prevented, and the adhesion between the polyester foam sheet and the polyester film is suitable within the weight range described above. It is possible to implement the performance and to suppress the peeling between the polyester foam sheet and the polyester film.

In addition, the average particle size of the low melting point polyester powder may be in the range of 1 to 5 μm. It can range from 3-5 μm, 4-5 μm or 2-4 μm. According to the present invention, by controlling the average particle diameter of the low melting point polyester powder within the above range, it can be uniformly dispersed when dispersed on the surface of the foam sheet 101 or film 102 .

In one example, the polyester foam sheet 101 of the composite sheet 100 according to the present invention can exhibit excellent processability by including calcium carbonate. Specifically, the polyester foam sheet 101 may include 0.5-9% by weight of calcium carbonate (CaCO ₃ ).

Specifically, the calcium carbonate (CaCO ₃ ) is inorganic particles, and by including the inorganic particles as described above, the foamed sheet 101 of the present invention has a uniform sheet surface and excellent thermoformability. can be shown.

The calcium carbonate may have a thermal conductivity of 1-3 kcal/mh°C. Specifically, the thermal conductivity of calcium carbonate may be 1.2-2.5 kcal/mh°C, 1.5-2.2 kcal/mh°C, or 1.8-2 kcal/mh°C. More specifically, the thermal conductivity of calcium carbonate can be 1.5-2.5 kcal/mh°C or 1.8-2.3 kcal/mh°C. The foamed sheet containing calcium carbonate as described above can have a uniform surface and exhibit excellent thermoformability by exhibiting excellent thermal conductivity.

For example, the calcium carbonate content may be 0.5-9% by weight based on the total weight of the foam sheet composition. Specifically, the content of calcium carbonate is 0.5-8 wt%, 0.6-7 wt%, 0.7-6 wt%, 0.8-5 wt%, 0.9-4 wt%, It can be 1-3% by weight, 2-3.5% by weight. As an example, it can be 1 wt% or 3 wt%.

That is, the polyester foam sheet 101 of the composite sheet 100 contains calcium carbonate, and the polyester film 102 is formed from a non-stretched film and can have excellent elongation.

Specifically, the composite sheet 100 according to the present invention is characterized by having an elongation of 200-600% after being treated at a temperature of 200° C. for 30 seconds. Specifically, the elongation of the composite sheet 100 can be 250-550%, 300-500%, 350-450%, or 370-430%.

Moreover, this invention provides the manufacturing method of a packaging container.

FIG. 2 is a diagram sequentially showing the manufacturing method of the packaging container according to the present invention. Referring to FIG. placing between the female mold 22 and pressing the female mold 21 and the male mold 22 to form the packaging container; A method for manufacturing the packaging container 10 is provided in which the surface temperature of the mold 21 is set to 40 to 200°C.

The composite sheet 100 may be a composite sheet in which a polyester foam sheet and a polyester film are laminated. Specifically, the method of manufacturing the composite sheet 100 is not particularly limited, but it may be manufactured through thermal fusion bonding or thermal bonding under pressure and heating conditions. More specifically, polyester powder or resin having a melting point of 180 to 250° C. or a softening point of 100 to 150° C. is dispersed or laminated on one surface of a polyester foam sheet, and a polyester film is laminated on the polyester foam sheet. can be

At this time, the lamination step can be controlled within the range of melting or softening of the polyester resin powder. For example, the laminating step may be performed at a temperature range of 100-250.degree. Specifically, the It can be performed through pressing at a temperature of 175-185°C, 160-180°C or 165-175°C for 1-3 minutes. Also, in the laminating step, a pressure higher than atmospheric pressure is applied. It can be molded into a desired shape under simultaneous application of heat and pressure. The applied pressure range is not particularly limited, and may be, for example, 1.5 to 10 atmospheres or 2 to 5 atmospheres.

For example, the method may further include preheating the polyester film at a temperature of 150° C. to 250° C. before laminating. Specifically, the Heat may be applied at a temperature of 185-195° C. for 1-60 seconds, 3-40 seconds or 5-20 seconds.

The polyester foam sheet may be prepared by dispersing a low melting point polyester powder on the surface of the polyester foam sheet.

In another embodiment, a low melting point polyester powder having a melting point of 180° C. to 250° C. or a softening point of 100° C. to 150° C. or a polyester film dispersed or laminated with a resin is laminated on a preheated polyester foam sheet. can include the step of The detailed description is as described above, so it will be omitted.

On the other hand, in the manufacturing method of the packaging container, the composite sheet 100 arranged between the female mold 21 and the male mold 22 can be thermoformed into the packaging container 10 . The thermoforming includes vacuum forming, air pressure forming, or vacuum pressure forming combining vacuum forming and pressure forming, using a male mold (plug), or using a male mold 22, followed by vacuum molding. and/or thermoforming methods such as pressure forming can be used.

Referring to FIG. 2, FIG. 2(a) illustrates the placement stage of placing the composite sheet 100 between the female mold 21 and the male mold 22 of the molding apparatus prior to molding the composite sheet 100. indicates FIG. 2(b) is a diagram showing the stretching process and the heating process. As shown in FIG. 2(b), the male mold 22 is lowered to stretch the composite sheet 100, and Vacuum suction from 21 is formed into the cavity shape of a female mold 21 and heat is applied. FIG. 2C shows that the molded composite sheet 100 is shaped into the shape of the male mold 22 by pressurization of the male mold 22 and compressed air from the female mold 21, It shows that the packaging container 10, which is the final molded product, is molded. Next, the molded packaging container 10 is removed by raising the male mold 22 after cooling.

On the other hand, the foamed sheet included in the composite sheet 100 can be a foamed sheet manufactured by melting a polyester resin introduced into an extruder and extruding and foaming it.

Specifically, the method for manufacturing the packaging container may include a step of manufacturing a foam sheet, and in one example, the step of manufacturing a polyester foam sheet is a foaming process of foaming a polyester resin to manufacture a foam sheet. can include The foaming process can be performed using various types of extruders. The foaming process is large and can be done through bead foaming or extrusion foaming, with extrusion foaming being preferred. The extrusion foaming can simplify the process steps by continuously extruding and foaming the resin melt, and mass production is possible. etc. can be prevented, and more excellent compressive strength can be achieved.

For example, various forms of additives may be added during the process of manufacturing the polyester foam sheet according to the present invention. Said additives can be introduced into fluid connecting lines or during the foaming process as required. The additive may have barrier performance, hydrophilic function, waterproof function, etc. Specifically, the additive may be a thickener, a surfactant, a hydrophilic agent, a heat stabilizer, a waterproof agent, or a cell size enlarging agent. , infrared attenuators, plasticizers, fire retardant chemicals, pigments, elastomeric polymers, extrusion aids, antioxidants, nucleating agents, anti-skid agents and UV absorbers. can include Specifically, in the method for producing a foamed sheet of the present invention, one or more of a thickener, a nucleating agent, a heat stabilizer and a foaming agent can be added, and one of the functional additives listed above can be added. The above can be further included.

For example, in the steps of manufacturing the foamed sheet of the present invention, thickening agents, hydrophilizing agents, heat stabilizers, waterproofing agents, cell size enlarging agents, infrared attenuating agents, plasticizers, fire retardant chemicals, pigments, elastic polymers, extrusion One or more additives selected from the group consisting of adjuvants, antioxidants, anti-slip agents and UV absorbers can be introduced into the fluid connection line. Additives that are not introduced into the fluid connection line among the additives required during the production of the foamed sheet can be introduced during the extrusion process.

Meanwhile, the surface temperature of the male mold 22 and the surface temperature of the cavity of the female mold 21 may be different from each other in the molding step. Preferably, the surface temperature of the female mold 21 can be 40-200°C, for example, 40-180°C, 40-150°C, 40-120°C, 40-100°C, 40-80°C, 40°C ~60°C, 60-200°C, 80-200°C, 100-200°C or 150-200°C. Also, the surface temperature of the male mold 22 can be 20-200°C, for example, 20-180°C, 20-150°C, 20-120°C, 20-100°C, 20-80°C, 20-200°C. It can be 60°C, 60-200°C, 80-200°C, 100-200°C or 150-200°C. In one example, the surface temperature of the male mold 22 can be 110°C and the surface temperature of the female mold 21 can be 145°C. Preferably, the male mold 22 contacts or presses the female mold 22 for 0.5-40 seconds, 1-30 seconds, 3-20 seconds, or 5-15 seconds. In addition, the female mold 21 may have a structure in which a decompression hole 23 for decompressing a cavity, which is an internal space, is formed on one side.

Next, the method for manufacturing a packaging container according to the present invention may further include cooling the molded packaging container to a temperature range of -10 to 20°C. More specifically, the temperature of the cooling step is -5 to 18°C, -1 to 17°C, 1 to 16°C, 2 to 15°C, 3 to 14°C, 4 to 13°C, 5 to 12°C, 6 It can be ~11°C or 10°C. When the hot-formed packaging container is cooled to a temperature within the above range, the crystallinity of the polyester resin foam sheet can be formed in the range of 10 to 35%. When cooling is performed within the above temperature range, the degree of crystallinity of the polyester resin foam sheet is prevented from increasing excessively, and molding of the in-mold packaging container can be facilitated. can be manufactured.

FIG. 3 is a diagram showing a packaging container manufactured by the method for manufacturing a packaging container according to the present invention. Referring to FIG. 3, the packaging container manufacturing method of the present invention can manufacture the packaging container 10 that satisfies Equation 1 below. The packaging container 10 can include a receptacle and an opening. The storage part is a storage space (internal space) of the packaging container 10 and means a space surrounded by the bottom part 11 and the wall part 12 . The opening means a part opened at the upper end of the packaging container 10 .

[Formula 1]
0.01≦H/D≦2;

In formula 1,
H indicates the depth of the housing portion and is 1 to 15 cm,
D indicates the diameter of the opening.

For example, in Equation 1, the value of H/D may range from 0.01 to 2. Specifically, the range of H/D may range from 0.01 to 1.5, 0.01 to 1.2, 0.01-1.0, 0.01-0.8, 0.01-0.6, 0.01-0.4, 0.01-0.2, 0.2-2, 0.6- It can be 2, 1-2, 1.5-2, 0.6-1.2, 0.7-1.1, 0.8-1 or 0.85-0.95. From the above H/D value, it can be seen that the packaging container 10 of the present invention has excellent moldability and can be dip molded.

That is, as described above, by manufacturing the packaging container 10 using the composite sheet 100 including the polyester foam sheet 101 and the unstretched polyester film 102, excellent workability can be exhibited.

As an example, the packaging container 10 according to the present invention includes a bottom portion 11; a wall portion 12 extending upward along the circumference of the bottom portion 11 and having an open top end; The average thickness of the walls 12 can each be 2.0 mm or less. More specifically, the average thickness of the bottom portion 11 and the average thickness of the wall portion 12 are 0.8 to 2.0 mm, 0.9 to 1.8 mm, 1.0 to 1.6 mm, and 1.1 to 1.1 mm, respectively. It can be 1.4 mm or 1.2-1.3 mm. On the other hand, when the thickness of the bottom portion 11 and the wall portion 12 of the packaging container 10 is within the above range, it is possible to reduce the weight of the packaging container 10 and prevent deterioration of strength and rigidity.

Also, the ratio (T _a :T _{b ) of the average thickness (T a ) of the bottom portion 11 and the average thickness (T b ) of} the wall portion 12 may be in the range of 1:0.9 to 1.1. As an example, the ratio (T _a :T _{b ) of the average thickness (T a ) of the bottom portion 11 and the average thickness (T b ) of} the wall portion 12 is 1:0.9 to 1.05, 1:0.9. ~1.0, 1:0.9-0.95, 1:0.95-1.1, 1:0.95-1.0, or 1:0.97-0.99 .

That is, although the packaging container 10 according to the present invention is manufactured by dip molding, the thickness of the bottom portion 11 and the wall portion 12 can be substantially constant.

In one example, the packaging container 10 of the present invention may have a compressive strength of 4-25 kgf/cm ² when the H/D value is 1. Specifically, when the H/D value is 1, the packaging container 10 of the present invention has a compressive strength of 4 to 22 kgf/cm ² , 4 to 18 kgf/cm ² , 4 to 15 kgf/cm ² , 4 to 10 kgf/cm 2 . cm ² , 10-25 kgf/cm ² , 15-25 kgf/cm ² , or 10-15 kgf/cm ² . As an example, when the H/D value is 1, the packaging container 10 may have a compressive strength of 12 kgf/cm ² or 9 kgf/cm ² . By having the compressive strength as described above, the packaging container 10 of the present invention is excellent in durability.

On the other hand, as shown in FIG. 3, the upper end of the wall portion 12 may be formed with a flange 13 extending outwardly along the circumference of the wall portion 12 .

Also, as shown in FIG. 3, in the packaging container 10, the foam sheet 101 can be placed inside and the unstretched polyester film 102 can be placed outside, or vice versa. Also, the composite sheet 100 may be composed of two or more layers.

The packaging container 10 according to the present invention may include a polyester resin foam sheet 101 and a film 102, and the polyester resin may be polyethylene terephthalate (PET) resin. By using the PET resin, it can be environmentally friendly and easy to reuse.

Based on the standards of the Ministry of Food and Drug Safety for equipment, containers and packaging and their raw materials, when measuring the dissolution standards, the total dissolution amount of acetic acid, water and heptane should be 30 ppm or less, antimony, germanium, terephthalic acid, Isophthalic acid, acetaldehyde substances shall not be detected, and volatile substances shall not be detected when measuring residue specifications.

Specifically, the packaging container according to the present invention uses polyester resin, which is an eco-friendly material, as described above, so that the standards and standards for equipment and containers and packaging issued by the Ministry of Food and Drug Safety No. 2015-7 can be adjusted within acceptable limits.

By manufacturing the packaging container 10 using the composite sheet using such materials, the packaging container 10 that is friendly to the environment can be provided.

The present invention will now be described in more detail with reference to Examples and Experimental Examples.

However, the following examples and experimental examples merely illustrate the present invention, and the content of the present invention is not limited to the following examples and experimental examples.

Example 1
3% by weight of calcium carbonate and 97% by weight of PET resin are mixed, and based on 100 parts by weight of PET resin, 0.5 parts by weight of pyromellitic dianhydride and 0.1 parts by weight of Irganox (IRG 1010) are added. were mixed and heated at 280° C. to produce a resin melt. Next, 1.5 parts by weight of butane as a foaming agent based on 100 parts by weight of PET resin was put into the first extruder and extruded and foamed to produce a PET foam sheet with an average thickness of 1.0 mm. At this time, the density of the produced PET foam sheet was 460 kg/m ³ .

Then, an unstretched PET film having an average thickness of 30 μm and a density of 1,380 kg/m ³ was prepared.

After that, a low melting point PET powder was dispersed on one surface of the PET foam sheet, and the prepared PET film was laminated thereon to manufacture a composite sheet. At this time, the low-melting point PET powder used is mainly composed of a polyester resin having a melting point of 180-250°C or a softening point of 100-150°C.

The manufactured composite sheet was passed through an IR-type ceramic heater zone, and the upper heater was set to 400°C, the lower heater to 280°C, and the residence time to 30 seconds so that the surface temperature of the foamed sheet reached 160°C. After that, the temperature of the male mold (Plug) was set to 60° C. and the temperature of the female mold (Mold) was set to 40° C., and pressed for 10 seconds to produce a container.

A cup container design with a mold H/D of 0.91, a container depth (H) of 10.5 cm and an opening diameter (D) of 11.5 cm was applied.

Example 2
A packaging container was produced by molding in the same manner as in Example 1, except that the thickness of the unstretched PET film was 50 μm.

Comparative example 1
A packaging container was produced by molding in the same manner as in Example 1, except that a stretched PET film was used instead of the unstretched PET film. Meanwhile, the stretched PET film was a biaxially stretched film, specifically, a film with a tensile strength of 20 kg/mm ² .

Comparative example 2
A packaging container was produced by molding in the same manner as in Example 1, except that a non-stretched PP film was used instead of the non-stretched PET film.

Comparative example 3
A cup container (H/D 0.91) molded into a product of polystyrene (PS) chemically foamed PS foam sheet (density 730 kg/m ³ , thickness 1 mm) was purchased and compared.

Table 1 below summarizes the types of sheets and molding conditions in Examples and Comparative Examples.

Referring to Table 1, it was confirmed that when the composite sheet according to the present invention was used to form a packaging container, it was successfully formed without breakage. However, since the composite sheet of Comparative Example 1 used an already stretched film, it was not stretched even when heat was applied. In addition, in the case of Comparative Example 2, when a PP film was used and subjected to high temperature heat from a heater, the problem of deterioration of the film occurred.

Experimental example 1
In order to confirm the physical properties of the composite sheet and food container according to the present invention, high-temperature elongation was measured for the packaging containers of Examples and Comparative Examples. The results are shown in Table 2.

At this time, in order to measure the high temperature elongation, a tensile strength tester was placed in an oven, the size of the test piece was 70 mm in height × 25 mm in width, the test speed was 50 mm / min, and the gap size was 20 mm. It was set and measured after dwelling at an oven temperature of 200° C. for 30 seconds.

Referring to Table 2, the high temperature elongation of the composite sheets of Examples 1 and 2 of the present invention is 300% or more, and the high temperature elongation of the composite sheet of Comparative Example 1 is 200% or less. For example, it can be confirmed that the composite sheet of the present invention is excellent in high-temperature elongation.

Experimental example 2
In order to confirm the physical properties of the food container according to the present invention, the side/bottom thickness ratio and compressive strength were measured for the packaging containers of Examples and Comparative Examples, and the results are shown in Table 3.

At this time, the side/bottom thickness ratio was expressed as the ratio of the thickness of the bottom (bottom) to the thickness of the side after measuring the thickness of the central portion of the side and bottom.

The compressive strength was measured using a tensile strength tester with the bottom surface of the food container facing upward and then compressed at a test speed of 50 mm/min under maximum load.

Referring to Table 3, the side/bottom thickness ratios of Examples 1 and 2 were greater than or equal to 0.9, and the thickness ratios of the side and bottom surfaces were similar. On the other hand, the side/bottom thickness ratio of Comparative Example 2 is less than 0.8, indicating that the bottom is slightly thicker than the side. On the other hand, in the case of Comparative Example 1, the food packaging container was broken during molding, and the packaging container could not be manufactured.

Experimental example 3
The elution amount of harmful substances from the food containers manufactured in Example 1 and Comparative Example 3 was evaluated. Specifically, after heating the food container in an 800W microwave oven for 5 minutes, the amount of elution of harmful substances was measured, and the evaluation item showed that the results met the standards of Notification No. 2016-51 of the Ministry of Food and Drug Safety. . Evaluation items and results are shown in Table 4 below.

Referring to Table 4, since no volatile substances were detected in the food container according to the example, it was found to meet the criteria announced by the Ministry of Food and Drug Safety. However, in the case of the food container according to the comparative example, a large amount of 412 mg/kg of styrene remained. In addition, 4% acetic acid and water were not eluted from the food container according to the example. However, in the case of the food container according to the comparative example, 4% acetic acid and water were eluted. Therefore, it was confirmed that the food container according to the present application can significantly reduce the amount of residual and eluted harmful substances.

Claims (8)

a polyester foam sheet with an average thickness of 0.9 to 10 mm; and a polyester film with an average thickness of 15 to 200 μm formed on one or both sides of the foam sheet is laminated,
The polyester film is a non-stretched film,
A composite sheet having an elongation of 200-600% after being treated at a temperature of 200° C. for 30 seconds,
The polyester foam sheet has a density of 460 to 700 kg/m ³ ,
The tensile strength of the non-stretched film is 15 kg/mm ² or less, and the tensile strength is measured using a tensile strength tester with a test piece size of 70 mm in height × 25 mm in width, a test speed of 50 mm/min, and a gap size of 20 mm. measured under the conditions of
A composite sheet in which a polyester foam sheet and a polyester film are laminated via a polyester powder or a polyester resin containing repeating units represented by chemical formulas 1 and 2:

In the chemical formula 1 and chemical formula 2,
m and n represent the molar fraction of the repeating unit, and based on m+n=1, n is 0.05 to 0.5 and m is 0.5 to 0.95. Polyester foam sheet is polyethylene terephthalate foam sheet,
2. The composite sheet of Claim 1, wherein the polyester film is a polyethylene terephthalate film. placing the composite sheet of claim 1 between a female mold and a male mold of a molding apparatus;
pressing the female mold and the male mold to form;
In the molding step, the surface temperature of the female mold is set to 40 to 200°C. The composite sheet of claim 3 is formed by laminating a polyester film on a polyester foam sheet in which the polyester powder or polyester resin defined in claim 1 is dispersed or laminated on one side. Production method. The composite sheet is formed by laminating a polyester foam sheet on a polyester film in which the polyester powder or polyester resin defined in claim 1 is dispersed or laminated on one side. Production method. The method for manufacturing a packaging container according to claim 3, further comprising cooling the molded packaging container at -10 to 20°C. The method for manufacturing a packaging container according to claim 3, wherein the packaging container includes an accommodating portion and an opening and satisfies the following formula 1:
[Formula 1]
0.01≦H/D≦2;
In formula 1,
H indicates the depth of the housing portion and is 1 to 15 cm,
D indicates the diameter of the opening. The packaging container includes a bottom; a wall extending upwardly around the bottom and having an open top;
The average thickness of the bottom and the average thickness of the walls are each 0.8 to 2.0 mm,
The packaging container according to claim 7, wherein the ratio (T _a :T _b ) of the average bottom thickness (T _a ) and the average wall thickness (T _b ) is 1:0.9 to 1.1. Production method.

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