KR20190033180A - Food packaging container with excellent elongation, and preparation method thereof - Google Patents

Abstract

The present invention relates to a food packaging container with excellent elongation and a manufacturing method thereof. To this end, the food packaging container with excellent elongation includes a polyester resin forming sheet, thereby providing an advantage that strength from a product stacking load and an external impact generated in a distribution process is excellent by improving the elongation through control of the degree of crystallization.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a food packaging container having excellent elongation,

The present invention relates to a food packaging container excellent in elongation and a method of manufacturing the same.

Recently, retailers such as supermarkets, convenience stores, and supermarkets sell meat or meat products such as pigs, cows, and chickens in packaging containers, and then sell them using transparent film or lids to visually check their condition. This is because visual factors such as the color of meat or meat products have a significant impact on merchantability. Therefore, it is important that meat or meat products maintain the consumer's preferred freshness.

When the meat or meat products are packaged and sold as described above, it takes a certain period of time until the consumer consumes them through various distribution processes such as production, transportation, and sale, and inevitably receives various external forces. It is important that packaged products are kept fresh so that consumers can safely consume high quality meat or meat products.

Therefore, when meat or meat products are packed, packaging materials such as polypropylene (PP), polystyrene foam (PS foam) and the like are used, and fresh atmosphere And the like.

Conventional packaging materials have problems in that the container may be damaged or damaged in an optimal storage temperature of meat or meat products of 4 to 5 ° C or in a freezing storage environment of a home, which may cause deterioration of meat or meat products . In addition, foamed polystyrene, aka styrofoam, is a disposable packaging container, which is the main cause of pollution in the environmental aspect. It is currently recommended to change the styrofoam packaging material to a recyclable material gradually by regulation under the environmental law. The use of the Internet itself is in a trend of banning.

In particular, considering the weight and mass distribution of the contents of meat or meat products, the container may be damaged or damaged by impacts or external forces generated during the distribution process, resulting in deterioration of the product. Refrigerated or frozen storage Special containers with eco-friendly materials that can be recycled and formed in a low temperature environment considering special circumstances such as distribution and contents of heavy weight should be used.

Also, given the recent trends in the quality and size of meat or meat products, the market for and demand for packaged meat is increasing, so a variety of meat or meat products packaging containers need to be developed.

Korean Patent Publication No. 10-2012-0058347

The present invention provides a food packaging container comprising a polyester resin foam sheet and a method of manufacturing the same.

The present invention relates to a foam sheet of a polyester resin having no crystallization peak in the range of 110 to 180 占 폚 in DSC analysis; And

And a coating layer formed on one side or both sides of the foam sheet.

Further, according to the present invention,

Preparing a foamed sheet by extrusion foaming a polyester resin prepared by polymerizing an acid component and a diol component;

Forming a resin coating layer on one side or both sides of the foam sheet; And

Heating and pressurizing the foam sheet having the resin coating layer formed thereon to form a recessed shape having an upper opening,

Wherein the acid component comprises at least one of terephthalic acid and terephthalic acid derivatives and at least one of isophthalic acid, isophthalic acid derivative and phthalic anhydride,

Wherein the foam sheet does not have a crystallization peak in the range of 110 ° C to 180 ° C during DSC analysis.

The food packaging container according to the present invention is advantageous in that the polyester resin polymer contains various derivatives and thus the crystallization degree is controlled to form a thermosensitive property.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail.

It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

In the present invention, the terms " comprising " or " having ", and the like, specify that the presence of a feature, a number, a step, an operation, an element, a component, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

Therefore, the configurations shown in the embodiments described herein are merely the most preferred embodiments of the present invention and are not intended to represent all of the technical ideas of the present invention. Therefore, various equivalents And variations.

The present invention relates to a food packaging container comprising a foam sheet of a polyester resin.

Conventionally, packaging containers made of various materials such as polypropylene (PP), polystyrene foam (PS foam) and the like have been used so as to maintain the fresh state of food. However, the packaging container described above has a problem that the container may be damaged or damaged at a temperature of 4 to 5 ° C or in a freezing storage environment at home. In addition, expanded polystyrene, a so-called styrofoam, And it is recommended to change the styrofoam packaging materials to materials that can be recycled progressively by regulations in the environmental laws. It is in the trend of prohibiting the use of styrofoam packaging containers outside the country.

In particular, considering the weight and mass distribution of the contents of meat or meat products, the container may be damaged or damaged by impacts or external forces generated during the distribution process, resulting in deterioration of the product. Refrigerated or frozen storage Special containers with eco-friendly materials that can be recycled and formed in a low temperature environment considering special circumstances such as distribution and contents of heavy weight should be used.

In order to solve the above problem, the food packaging container according to the present invention includes a foamed sheet containing a polyester copolymer, and exhibits an appropriate degree of crystallinity, thereby improving its elongation and thus having an excellent impact strength.

Hereinafter, the foam sheet according to the present invention will be described in detail.

The present invention relates to a foam sheet of a polyester resin having no crystallization peak in the range of 110 to 180 占 폚 in DSC analysis; And

And a coating layer formed on one side or both sides of the foam sheet.

Wherein the foam sheet of the polyester resin comprises a repeating unit derived from an acid component and a diol component, wherein the acid component is at least one member selected from the group consisting of terephthalic acid derivatives, isophthalic acid derivatives and phthalic acid derivatives,

Wherein the diol component is selected from the group consisting of ethylene glycol derivatives, 2-methyl-1,3-propanediol, MP, neopentyl glycol, 1,2- 2-propanediol, diethylene glycol, and isosobide, and more preferably,

And a repeating unit derived from a terephthalic acid derivative and an ethylene glycol derivative in an amount of 80 mol% to 99 mol% based on the total repeating units,

The DSC analysis may not have a crystallization peak in the range of 110 ° C to 180 ° C.

Specifically, the foam sheet of the present invention may be a foam sheet of a polyester resin containing a repeating unit derived from an acid component and a diol component. For example, the acid component may contain a terephthalic acid derivative, and in some cases, it may further include at least one member selected from the group consisting of isophthalic acid derivatives and phthalic acid derivatives. In addition, the diol component may contain an ethylene glycol derivative. In some cases, 2-methyl-1,3-propanediol (MP), neopentyl glycol ), 1, 2-propanediol, diethylene glycol, and isosobide may be further included.

In one example, the repeating unit derived from the terephthalic acid derivative and the ethylene glycol derivative may be contained in an amount of 80 mol% to 99 mol% based on the total repeating units. Specifically, the repeating units derived from the terephthalic acid derivative and the ethylene glycol derivative may be contained in an amount of 80 mol% to 99 mol%, 85 mol% to 99 mol%, or 90 mol% to 99 mol% based on the total repeating units. More specifically, the repeating units derived from the terephthalic acid derivative and the ethylene glycol derivative may contain 92 mol% to 99 mol% or 96 mol% to 98 mol% with respect to 100 mol% of the total repeating units. When the above-mentioned content contains repeating units derived from a terephthalic acid derivative and an ethylene glycol derivative, the degree of crystallization of the foamed sheet can be adjusted to an appropriate range.

For example, in the acid component, the repeating unit derived from at least one member selected from the group consisting of an isophthalic acid derivative and a phthalic acid derivative may be contained in an amount of 1 mol% to 10 mol% based on the total repeating units. Specifically, the repeating unit derived from an isophthalic acid derivative or a phthalic acid derivative may be contained in an amount of 1 mol% to 8 mol% or 2 mol% to 4 mol% based on the total repeating units.

In the above-mentioned diol component, 2-methyl-1,3-propanediol (MP), neopentyl glycol, 1,2-propanediol (1,2 -propanediol, diethylene glycol, and isosobide may be contained in an amount of 1 mol% to 10 mol% based on the total repeating units . Specifically, 2-methyl-1,3-propanediol, MP, neopentyl glycol, 1,2-propanediol, The repeating unit derived from diethylene glycol or isosobide may be contained in an amount of 1 mol% to 8 mol% or 2 mol% to 4 mol% based on the total repeating unit%.

In the case of containing an acid component or a diol component as described above, the degree of freedom of the polyester resin copolymer can be increased to lower the melting point of the foam sheet, thereby lowering the crystallization degree of the foam sheet and preventing the food packaging container from hardening And the elongation can be improved, so that the strength from the laminated load or external impact can be improved. In addition, the polyester resin as described above has excellent heat resistance and cold resistance, so that the food packaging container can be easily frozen and stored.

In one example, the food packaging container according to the present invention may have no crystallization peak in the range of 110 ° C to 180 ° C in the differential scanning calorimetry (DSC) analysis. Specifically, in the differential scanning calorimetry (DSC) analysis, crystallization peaks may not be present in the range of 120 ° C to 160 ° C. In the case of a conventional polyester resin foam sheet, a food packaging container having a crystallization peak in a range of 110 ° C to 180 ° C in the differential scanning calorimetry (DSC) analysis is hardened, but the food packaging container according to the present invention has crystallinity So that the elongation is excellent.

For example, the crystallization degree of the food packaging container according to the present invention may be from 10% to 20% on average. Specifically, the degree of crystallization of the food packaging container may be from 12% to 17% on average, and the food packaging container exhibiting the degree of crystallization in the above range is excellent in impact strength so that the food packaging container is deformed from the lamination load and / . Thus, the product contained in the food packaging container can be prevented from being deteriorated.

Further, in the food packaging container of the present invention, the thickness of the foam sheet may be 0.5 mm to 5 mm. Specifically, the thickness of the foam sheet may be 0.8 mm to 4.0 mm and 1.0 mm to 3.5 mm, and more specifically, the thickness of the foam sheet may be 1.0 mm to 4.0 mm or 1.3 mm to 3.0 mm.

The foam sheet of the polyester resin may satisfy the following formula (1): " (1) "

[Equation 1]

| V ₁ -V ₀ | / V ₀ x 100? 5%

In the above equation (1)

V ₀ is the volume (mm ³ ) of the foam sheet before exposure for 3 hours at 150 ° C,

V ₁ is the volume (mm ³ ) of the foam sheet after exposure at 150 ° C for 3 hours.

Specifically, the rate of dimensional change of the foamed sheet sample before and after the exposure at 150 캜 for 3 hours was measured. This is a measurement time in which the foam sheet corresponds to the actual use environment for heat. For example, the volume may mean a value calculated by multiplying the length of each foam sheet by the length of each of the width and thickness. For example, the rate of dimensional change according to Equation 1 may range from 0.01 to 5%, from 0.01 to 3%, or from 0.01 to 1%. By satisfying the value of the expression (1) in the above range, it can be seen that the foam sheet according to the present invention hardly undergoes morphological change even when used in a high temperature environment. As a result, it can be seen that the foam sheet according to the present invention is excellent in heat resistance.

As one example, the foam sheet may have a barrier property, a hydrophilization function, or a waterproof function, and may include a surfactant, a hydrophilizing agent, a heat stabilizer, a waterproofing agent, a cell size enlarging agent, an infrared attenuator, One or more functional additives selected from the group consisting of a chemical agent, a pigment, an elastic polymer, an extrusion aid, an antioxidant, a nucleating agent, an anti-static agent and a UV absorber. Specifically, the resin foam of the present invention may contain a thickener, a nucleating agent, a heat stabilizer and a foaming agent.

Although the thickening agent is not particularly limited, for example, pyromellitic dianhydride (PMDA) may be used in the present invention.

Examples of the nucleating agent include at least one of talc, mica, silica, diatomaceous earth, alumina, titanium oxide, zinc oxide, magnesium oxide, magnesium hydroxide, aluminum hydroxide, calcium hydroxide, potassium carbonate, calcium carbonate, magnesium carbonate, , Sodium hydrogencarbonate, and glass beads. These nucleating agents can play a role in imparting functionality and reducing the cost of the resin foam. Specifically, Talc may be used in the present invention.

The heat stabilizer may be an organic or inorganic compound. The organic or inorganic phosphorus compound may be, for example, phosphoric acid and organic esters thereof, phosphorous acid and organic esters thereof. For example, the heat stabilizer may be a commercially available material, such as phosphoric acid, alkyl phosphate or aryl phosphate. Specifically, in the present invention, the heat stabilizer may be triphenyl phosphate, but it is not limited thereto, and it can be used within a usual range without limitation as long as it can improve the thermal stability of the resin foam.

Examples of the foaming agent include physical foaming agents such as N ₂ , CO ₂ , freon, butane, pentane, neopentane, hexane, isohexane, heptane, isoheptane and methyl chloride, azodicarbonamide- (P, P'-oxy bis (benzene sulfonyl hydrazide)], N, N'-dinitroso pentamethylene tetramine-based compounds, and the like. Specifically, CO ₂ can be used in the present invention.

In one example, the food packaging container comprises a foam sheet of polyester resin; An ethylene vinyl alcohol coating layer; And a polyethylene resin layer may be sequentially laminated. Specifically, an ethylene vinyl alcohol coating layer; A foamed sheet of a polyester resin; An ethylene vinyl alcohol coating layer; And a polyethylene resin layer may be sequentially laminated.

For example, the thickness of the ethylene-vinyl alcohol coating layer may be 30 탆 to 200 탆. Specifically, the thickness of the ethylene vinyl alcohol coating layer may be 40 to 180 탆, 50 to 150 탆 or 20 to 80 탆, and more specifically, the thickness of the ethylene vinyl alcohol coating layer may be 30 탆 to 80 탆, To 100 [mu] m or 100 [mu] m to 150 [mu] m. By including the ethylene vinyl alcohol coating layer as described above, it is possible for the food packaging container to discharge the gas generated in the food inside the food container to the outside, and at the same time, the oxygen supply from the outside can be blocked.

Also, the thickness of the polyethylene resin layer may be 20 탆 to 150 탆. Specifically, the thickness of the polyethylene resin layer may be 25 탆 to 130 탆, 30 탆 to 120 탆, or 35 탆 to 100 탆, and more specifically, the thickness of the resin layer may be 30 탆 to 80 탆, Or 100 [mu] m to 150 [mu] m. By including the polyethylene resin layer having the thickness as described above, it is possible for the food packaging container to discharge the gas generated from the food inside the food container to the outside, and at the same time, the oxygen supply from the outside can be blocked.

As an example, a food packaging container according to the invention can be up to temperature and under a relative humidity of 50% of the oxygen transmission rate ^{23 ℃, 10cc / m 2 /} 24h. Specifically, the oxygen permeability of food packaging containers may be from 0.1 to ^{10 cc / m 2 / 24h,} 0.1 to 5 cc / m ² / 24h, or from 0.1 to 3 cc / m ² / 24h. The food packaging container according to the present invention can prevent the food in the food packaging container from reacting with oxygen and decaying by having the oxygen permeability within the above range, thus making it easy to store food.

The food packaging container according to the present invention comprises a foam sheet of a polyester resin having no crystallization peak in the range of 110 to 180 占 폚 in DSC analysis; And a coating layer formed on one or both sides of the foam sheet, wherein the foam sheet has an upper opening; And

A lid portion including a polyester or nylon resin layer and a coating layer formed on one or both sides of the polyester or nylon resin layer and having a shape corresponding to an upper opening of the food containing portion,

The upper surface of the rim of the food compartment forming the upper opening and the lower surface of the lid may be respectively coated with the same kind of resin.

As an example, the food packaging container according to the present invention may have an impact strength of at least 5 KJ / m < ² > at a temperature of -10 DEG C according to ASTM D 256. Specifically, the impact strength of the food packaging container may be 5 to 50 KJ / m ² , 8 to 45 KJ / m ² or 10 to 40 KJ / m ² . The food packaging container according to the present invention has an impact strength in the above range, so that the food packaging container can protect the product from external impact.

Further, the food packaging container according to the present invention may have a moisture permeability (WVTR) of less than 400 mg / m ² day under a temperature of 23 ° C and a relative humidity of 50%. Specifically, the moisture permeability of the food packaging container may be 10 to 350 mg / m ² day, 20 to 300 mg / m ² day or 30 to 250 mg / m ² day. The food packaging container according to the present invention has a water permeability within the above range, so that the food in the food packaging container can be prevented from reacting with oxygen and decaying, so that the food packaging container can be easily stored.

In one example, the food storage part comprises a foamed sheet of a polyester resin; An ethylene vinyl alcohol coating layer; And a polyethylene resin layer, wherein the lid portion comprises a polyester or nylon resin layer; An ethylene vinyl alcohol coating layer; And a polyethylene resin layer are laminated in this order, and the polyethylene resin layer of the food containing portion and the polyethylene resin layer of the lid portion are bonded to each other so as to face each other.

Specifically, the lid part is joined on the food compartment in the state where the object to be stored is housed in the food compartment, and the internal space formed by the bonding of the food compartment and the lid part may be filled with nitrogen gas have.

Further, according to the present invention,

Preparing a foamed sheet by extrusion foaming a polyester resin prepared by polymerizing an acid component and a diol component;

Forming a resin coating layer on one side or both sides of the foam sheet; And

Heating and pressurizing the foam sheet having the resin coating layer formed thereon to form a recessed shape having an upper opening,

Wherein the acid component comprises at least one of terephthalic acid and terephthalic acid derivatives and at least one of isophthalic acid, isophthalic acid derivative and phthalic anhydride,

Wherein the foamed sheet has no crystallization peak in a range of 110 ° C to 180 ° C in DSC analysis.

Specifically, in the step of polymerizing an acid component and a diol component to prepare a polyester resin, the acid component may necessarily contain a terephthalic acid derivative, and in some cases, a terephthalic acid derivative Or more species. In addition, the diol component may contain an ethylene glycol derivative. In some cases, 2-methyl-1,3-propanediol (MP), neopentyl glycol ), 1, 2-propanediol, diethylene glycol, and isosobide may be further included.

In one example, the produced polyester resin may contain 80 mol% to 99 mol% of repeating units derived from a terephthalic acid derivative and an ethylene glycol derivative, based on the total repeating units. Specifically, the repeating units derived from the terephthalic acid derivative and the ethylene glycol derivative may be contained in an amount of 80 mol% to 99 mol%, 85 mol% to 99 mol%, or 90 mol% to 99 mol% based on the total repeating units. More specifically, the repeating units derived from the terephthalic acid derivative and the ethylene glycol derivative may contain 92 mol% to 99 mol% or 96 mol% to 98 mol% with respect to 100 mol% of the total repeating units. When the above-mentioned content contains repeating units derived from a terephthalic acid derivative and an ethylene glycol derivative, the degree of crystallization of the foamed sheet can be adjusted to an appropriate range.

For example, in the acid component, the repeating unit derived from at least one member selected from the group consisting of an isophthalic acid derivative and a phthalic acid derivative may be contained in an amount of 1 mol% to 10 mol% based on the total repeating units. Specifically, the repeating unit derived from an isophthalic acid derivative or a phthalic acid derivative may be contained in an amount of 1 mol% to 8 mol% or 2 mol% to 4 mol% based on the total repeating units.

In the above-mentioned diol component, 2-methyl-1,3-propanediol (MP), neopentyl glycol, 1,2-propanediol (1,2 -propanediol, diethylene glycol, and isosobide may be contained in an amount of 1 mol% to 10 mol% based on the total repeating units . Specifically, 2-methyl-1,3-propanediol, MP, neopentyl glycol, 1,2-propanediol, The repeating unit derived from diethylene glycol or isosobide may be contained in an amount of 1 mol% to 8 mol% or 2 mol% to 4 mol% based on the total repeating units.

When an acid component or a diol component is included as described above, the degree of freedom of the resin can be increased to lower the melting point of the foam sheet. Accordingly, the foam sheet has a low degree of crystallization, and the foam sheet can be prevented from hardening at the time of thermoforming have.

In one example, the step of producing a polyester resin may be carried out by mixing an isophthalic acid derivative or a phthalic acid derivative in an acid component at a ratio of 1 mol% to 10 mol% with respect to the total of the acid component and the diol component. Specifically, an isophthalic acid derivative or a phthalic acid derivative in an acid component may be mixed in an amount of 1 mol% to 8 mol% or 2 mol% to 4 mol% based on the total amount of the acid component and the diol component.

In addition, the step of preparing the polyester resin may be carried out in the diol component using 2-methyl-1,3-propanediol (MP), neopentyl glycol, 1,2-propanediol 1,2-propanediol, diethylene glycol or isosobide can be mixed in an amount of 1 mol% to 10 mol% based on the total amount of the acid component and the diol component. Specifically, in the diol component, 2-methyl-1,3-propanediol, MP, neopentyl glycol, 1,2-propanediol (1,2- propanediol, diethylene glycol or isosobide may be mixed in an amount of 1 mol% to 8 mol% or 2 mol% to 4 mol% based on the total amount of the acid component and the diol component.

In one example, the step of producing the foam sheet may include a foaming process of foaming the polyester resin to produce a foam. The foaming process can be performed using various types of extruders. The foaming process can be largely carried out through bead foaming or extrusion foaming, and extrusion foaming is preferred. The extrusion foaming can simplify the process steps by continuously extruding and foaming the resin melt, and can be mass-produced. It prevents cracks and granular fracture between the beads at the time of bead foaming, And compressive strength can be realized.

For example, in the step of producing the foam sheet, the foam sheet may be formed to a thickness of 0.5 mm to 5 mm. Specifically, the foam sheet may be formed to a thickness of 0.8 mm to 4.0 mm and 1.0 mm to 3.5 mm, and more specifically, the foam sheet may be formed to a thickness of 1.0 mm to 4.0 mm or 1.3 mm to 3.0 mm .

As one example, the step of producing the foam sheet according to the present invention may be carried out in various types of additives. The additive may be injected into the fluid connection line, or may be injected during the foaming process, if necessary. Examples of the additive may include a barrier property, a hydrophilization function or a waterproof function, and may be selected from the group consisting of a thickener, a surfactant, a hydrophilizing agent, a heat stabilizer, a waterproofing agent, a cell size expanding agent, an infrared attenuator, a plasticizer, At least one functional additive selected from the group consisting of a pigment, an elastic polymer, an extrusion aid, an antioxidant, a nucleating agent, an antistatic agent, and a UV absorber. Specifically, the method for manufacturing a foam of the present invention may contain at least one of a thickener, a nucleating agent, a heat stabilizer and a foaming agent, and may further include at least one of the above-mentioned functional additives.

For example, the step of preparing the foam sheet of the present invention can be carried out by using a thickener, a hydrophilizing agent, a heat stabilizer, a waterproofing agent, a cell size enlarging agent, an infrared attenuator, a plasticizer, a fire retardant chemical, a pigment, an elastic polymer, One or more additives selected from the group consisting of a nucleating agent, an anti-static agent, and a UV absorber may be introduced into the fluid connection line. Of the additives required in the production of the foam, the additives which have not been introduced into the fluid connection line can be put in the extrusion process.

Although the thickening agent is not particularly limited, for example, pyromellitic dianhydride (PMDA) may be used in the present invention.

Examples of the nucleating agent include at least one of talc, mica, silica, diatomaceous earth, alumina, titanium oxide, zinc oxide, magnesium oxide, magnesium hydroxide, aluminum hydroxide, calcium hydroxide, potassium carbonate, calcium carbonate, magnesium carbonate, , Sodium hydrogencarbonate, and glass beads. These nucleating agents can play a role in imparting functionality and reducing the cost of the resin foam. Specifically, Talc may be used in the present invention.

The heat stabilizer may be an organic or inorganic compound. The organic or inorganic phosphorus compound may be, for example, phosphoric acid and organic esters thereof, phosphorous acid and organic esters thereof. For example, the heat stabilizer may be a commercially available material, such as phosphoric acid, alkyl phosphate or aryl phosphate. Specifically, in the present invention, the heat stabilizer may be triphenyl phosphate, but it is not limited thereto, and it can be used within a usual range without limitation as long as it can improve the thermal stability of the resin foam.

Examples of the foaming agent include physical foaming agents such as N ₂ , CO ₂ , freon, butane, pentane, neopentane, hexane, isohexane, heptane, isoheptane and methyl chloride, azodicarbonamide- (P, P'-oxy bis (benzene sulfonyl hydrazide)], N, N'-dinitroso pentamethylene tetramine-based compounds, and the like. Specifically, CO ₂ can be used in the present invention.

The waterproofing agent is not particularly limited and includes, for example, silicone, epoxy, cyanoacrylate, polyvinyl acrylate, ethylene vinyl acetate, acrylate, polychloroprene, polyurethane and polyester resins , A mixture of polyol and polyurethane resin, a mixture of acrylic polymer and polyurethane resin, a polyimide, and a mixture of cyanoacrylate and urethane.

The forming of the coating layer on one side or both sides of the foam sheet may further comprise: Specifically, the coating layer may include ethylene vinyl alcohol. For example, in the step of forming the coating layer, a coating layer may be formed by coating (or applying) ethylene vinyl alcohol on one side or both sides of the foamed sheet using an extrusion T-die prior to the processing step. By forming the coating layer, moisture and / or oxygen permeability of the food packaging container can be kept low.

For example, the coating layer may be formed to a thickness of 20 to 150 탆. Specifically, the coating layer may be formed to a thickness of 25 탆 to 130 탆, 30 탆 to 120 탆 or 35 탆 to 100 탆, and more specifically, the coating layer may have a thickness of 30 탆 to 80 탆, 60 탆 to 100 탆, To 150 mu m.

In one example, the method for producing a foamed sheet according to the present invention may further comprise the step of forming a resin layer on the coating layer after the step of forming the coating layer on one side or both sides of the foam sheet. Specifically, the resin layer may be a polyethylene resin layer. For example, in the step of forming the resin layer, a resin layer may be formed by melting a polyethylene resin using an extruded T-die before coating the foam sheet, and coating the foamed sheet on one surface of the foam sheet. By forming the resin layer as described above, moisture and / or oxygen permeability of the food packaging container can be kept low.

For example, the resin layer may be formed to a thickness of 30 to 200 탆. Specifically, the resin layer may be formed to a thickness of 40 탆 to 180 탆, 50 탆 to 150 탆, or 20 탆 to 80 탆, and more specifically, the resin layer may have a thickness of 30 탆 to 80 탆, And can be formed to a thickness of 100 mu m to 150 mu m.

In one example, the step of heating and pressurizing the foamed sheet having the resin coating layer formed thereon to form a recessed shape with an upper opening may be performed by heating and heating the foamed sheet at a temperature ranging from 300 DEG C to 400 DEG C on average, at a pressure of 4 mm / min, And pressurized.

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

However, the following Examples and Experimental Examples are merely illustrative of the present invention, and the present invention is not limited to the following Examples and Experimental Examples.

Example  One

Terephthalic acid and ethylene glycol were added to the ester reaction tank, and a typical polymerization reaction was carried out at 258 ° C to prepare a polyethylene terephthalate polymer (PET oligomer) having a reaction rate of about 96%. 2-methyl-1,3-propanediol (MPD) was mixed with the prepared polyethylene terephthalate (PET) in an amount ratio of 2 mol%, and an esterification reaction catalyst was added to carry out an esterification reaction at 250 占 2 占Respectively. Then, a condensation polymerization catalyst was added to the obtained reaction mixture, and the condensation polymerization reaction was carried out while controlling the final temperature and pressure in the reaction vessel to be 280 ± 2 ° C. and 0.1 mmHg, respectively, to prepare a copolymer polyester resin.

0.5 part by weight of pyromellitic dianhydride, 0.5 part by weight of talc, and 0.1 part by weight of Irganox (IRG 1010) were mixed with 100 parts by weight of the polyester resin, and heated at 280 degrees to prepare a resin melt. Then, 3 parts by weight of butane as a foaming agent was added to the first extruder based on 100 parts by weight of PET resin, and extrusion foaming was carried out to form a foam layer having a thickness of 2 mm to prepare a polyester resin foam sheet.

Then, an EVOH resin was placed on the foam sheet, and the EVOH melt was heated to 100 ° C. to prepare an EVOH melt. The EVOH melt was extrusion-coated on a T-die maintained at 90 ° C. to form a coating layer.

A polyethylene resin was placed in a separate extruder on the foamed sheet on which the coating layer was formed, heated at 170 DEG C to prepare a resin melt, and extrusion coated with a T-die maintained at 150 DEG C to form a resin layer. Then, the foamed sheet was heated and pressurized at a temperature of 300 ° C to 400 ° C at a pressure of 4 mm / min to prepare a food packaging container.

Comparative Example  One

A foam sheet was prepared in the same manner as in Example 1, except that 2-methyl-1,3-propanediol (MPD) was not mixed.

Experimental Example  One

The gas barrier properties, water permeability, heat resistance and low temperature impact resistance (cold resistance) of the food packaging container prepared in Example 1 and Comparative Example 1 were measured. The measurement conditions are described below, and the results are shown in Table 1 below.

1) Gas barrier property measurement

Based on ASTM F 1249, the water permeability was measured at a temperature of 37.8 DEG C and a relative humidity of 100%.

2) Low temperature impact strength measurement

Using the resin foams prepared in Example 1 and Comparative Example 1, cold resistance test was carried out. The measurement method was -10 ° C impact strength according to ASTM D 256 conditions.

3) Secondary foaming rate

Secondary foaming refers to the foaming that occurs when the foam produced by extrusion is preheated during the secondary processing of the molding, and the change in thickness is measured after exposing the foam at a temperature of 215 캜 for 30 seconds.

4) Elongation measurement

Under the AST, D 882 conditions, both ends of a specimen of 165 mm X 19 mm were fixed with a fixture and pulled in the axial direction of the specimen to measure the rate of change of the predefined line drawn by the specimen.

Moisture permeability
(g / m ² · day) Low temperature impact strength
(kJ / m ² ) Secondary foaming rate
(%) Elongation
(%) Example 1 5.0 31 200 8.2 Comparative Example 1 6.0 33 210 5.9

Referring to Table 1, the foam sheet (Example 1) according to the present invention exhibited similar physical properties to those of Comparative Example 1 in terms of physical properties of moisture permeability and low temperature impact strength as compared with Comparative Example 1, It can be seen that the elongation (tensile strain) is remarkably improved. As a result, it can be confirmed that the foam sheet of the present invention has an increased elongation including a polyester resin. By having the excellent elongation as described above, it is possible to prevent the container from being damaged by the contents and the external impact under the conditions of refrigeration and freezing supplementation and circulation process.

Secondary foaming means that the formed sheet is foamed once as it is heated for molding, and in the case of Example 1, the moldability is improved by forming a thickness of more than a proper thickness through secondary foaming On the other hand, in the case of Comparative Example 1, it is confirmed that the elongation is decreased due to the secondary foaming in the molding process.

Therefore, the foam sheet according to the present invention can remarkably improve the elongation while maintaining excellent water permeability and low temperature impact strength required for food containers, and can achieve excellent formability.

Claims (11)

A foam sheet of a polyester resin having no crystallization peak in the range of 110 to 180 占 폚 in DSC analysis; And
And a coating layer formed on one or both sides of the foam sheet.
The method according to claim 1,
In the food packaging container,
A foamed sheet of a polyester resin; An ethylene vinyl alcohol coating layer; And a polyethylene resin layer are sequentially laminated.
The method according to claim 1,
In the food packaging container,
An ethylene vinyl alcohol coating layer; A foamed sheet of a polyester resin; An ethylene vinyl alcohol coating layer; And a polyethylene resin layer are sequentially laminated.
The method according to claim 1,
Wherein the foam sheet of the polyester resin satisfies the following formula (1): " (1) "
[Equation 1]
| V ₁ -V ₀ | / V ₀ x 100? 5%
In the above equation (1)
V ₀ is the volume (mm ³ ) of the foam sheet before exposure for 3 hours at 150 ° C,
V ₁ is the volume (mm ³ ) of the foam sheet after exposure at 150 ° C for 3 hours.
A foam sheet of a polyester resin having no crystallization peak in the range of 110 to 180 占 폚 in DSC analysis; And a coating layer formed on one or both sides of the foam sheet, wherein the foam sheet has an upper opening; And
A lid portion including a polyester or nylon resin layer and a coating layer formed on one or both sides of the polyester or nylon resin layer and having a shape corresponding to an upper opening of the food containing portion,
Wherein the upper surface of the rim portion of the food containing portion forming the upper opening portion and the lower surface of the lid portion are respectively coated with the same kind of resin.
6. The method of claim 5,
Wherein said food packaging container has an impact strength of at least 5 KJ / m < ² > at a temperature of -10 DEG C according to ASTM D 256.
6. The method of claim 5,
Wherein the food storage part comprises: a foamed sheet of a polyester resin; An ethylene vinyl alcohol coating layer; And a polyethylene resin layer are sequentially laminated,
The lid portion may comprise a polyester or nylon resin layer; An ethylene vinyl alcohol coating layer; And a structure in which a polyethylene resin layer is sequentially laminated,
Wherein the polyethylene resin layer of the food storage portion and the polyethylene resin layer of the lid portion are bonded to each other so as to face each other.
6. The method of claim 5,
Wherein the lid portion is joined on the food storage portion in a state where an object to be stored is stored in the food storage portion,
Wherein the inner space formed by the bonding of the food storage portion and the lid portion is in a state filled with nitrogen gas.
Preparing a foamed sheet by extrusion foaming a polyester resin prepared by polymerizing an acid component and a diol component;
Forming a coating layer on one side or both sides of the foam sheet; And
Heating and pressurizing the foam sheet having the resin coating layer formed thereon to form a recessed shape having an upper opening,
Wherein the acid component comprises at least one of terephthalic acid and terephthalic acid derivatives and at least one of isophthalic acid, isophthalic acid derivative and phthalic anhydride,
Wherein the foamed sheet has no crystallization peak in a range of 110 ° C to 180 ° C in DSC analysis.
10. The method of claim 9,
Wherein the content of at least one of the isophthalic acid, the isophthalic acid derivative and the phthalic anhydride is 1 mol% to 10 mol% with respect to the total of the acid component and the diol component.
10. The method of claim 9,
Wherein the diol component comprises at least one of ethylene glycol, 2-methyl-1,3-propanediol, niopentyl glycol, 1,2-propanediol, diethylene glycol and isosorbide. ≪ / RTI >