JPH07300160A - Retort-sterilizable food package - Google Patents

Abstract

PURPOSE:To obtain clear prints by covering a food container comprising a base layer of gas barrier resin and heat sealing layer of thermoplastic resin, with a sheet-shaped lid material arranged with gas barrier resin layer, heat sealing resin layer, and print on both sides of synthetic paper. CONSTITUTION:A retort-sterilizable food package comprises a food container (A) that holds foods such as hamburgers in recesses 2 and a sheet-shaped lid (B) covering the recess 2. The food container (A) is thermoformed from a laminate of a base layer (A1) of gas barrier resin on a heat sealing layer (A2) of thermoplastic resin with a melting point of 65-124 deg.C. The sheet-shaped lid (B) is a laminate of a base layer of synthetic paper (B1) with an opacity of 85% or more and whiteness of 85% or more, gas barrier resin layers (B2), (B2') on the base layer (B1), thermoplastic resin heat sealing resin layer B3 with a melting point of 65-124 deg.C on one side, and prints (B4), (B4') are inserted between the layers (B2) and (B1), and between (B1) and (B2'), respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a retort sterilization package for processed meat products such as hamburgers and meatballs.

[0002]

2. Description of the Related Art Conventionally, as a retort pouch for this processed meat product, an ethylene / vinyl acetate copolymer having a melting point of 65 to 124 ° C. on the inner surface of a printed aluminum foil,
A heat-sealable resin layer such as low-density polyethylene or Surlyn is provided, and a laminated film obtained by laminating a transparent film such as polypropylene, polyethylene or polyethylene terephthalate on the outer surface is used as a material, and a bag is formed from this.
The bag is filled with processed foods such as hamburger steak and meatballs and meat juice, and then the bag opening is heat-sealed at 120 to 140 ° C., and this is heat-sterilized in a retort kettle at about 125 ° C. for 20 to 30 minutes. Retort pouches are on sale.

Recently, it has been requested by some consumers that the contents of the retort pouch can be seen through from the outside of the packaging.
A gas barrier resin is used as a base layer (A1), and a thermoplastic resin heat seal layer (A having a melting point of 65 to 124 ° C.) is formed on the surface of the base layer (A1).
The laminated sheet obtained by laminating 2) is thermoformed to store food in the food storage recess of the transparent food container (A) provided with the food storage recess, and then the opening of the food container is filled with the surface layer having no surface layer. A trade name, a manufacturer, a manufacturing date, etc. are printed on the back surface of the oriented polypropylene film (b1), and the biaxially stretched polyethylene terephthalate film (b3) is attached to the adhesive layer of a mixture of linear low density polyethylene and branched low density polyethylene ( b1 / b2 / b3 / b4 having a heat seal layer (b4) having a melting point of 60 to 124 ° C. adhered on the opposite side and bonded on b2)
The sheet-like lid material (b) having a transparent laminated structure of
Then, the heat-sealing layer (A2) of the container and the heat-sealing layer (b4) of the lid material are heated at 120 to 140 ° C. from the lid material (b) side with a heating roll to fuse and seal the container. The sealed food container is put in a retort kettle at a temperature of about 110 to 135 ° C. for 5 to 30 minutes for sterilization.

This retort pouch food is put in boiling water as it is for cooking, or the lid is opened and the container is microwaved for cooking, or the contents are transferred to a pan and cooked for eating. There is. Such a retort-packed food curls to a height of 2 to 3 mm toward the lid side at the heat-sealed portion of the container (A) and the lid member (b), especially the edge (flange portion) of the container after retort sterilization (countermeasure). There is a drawback (Fig. 2), and because the lid material (b) is also transparent, the contrast with the printing of the lid material is poor due to the gravy, and the printed recipe,
There is a drawback that the characters of the manufacturing date are difficult to read.

[0005]

DISCLOSURE OF THE INVENTION The present invention provides a retort sterilized food package in which the letters and patterns printed on the lid material have a clear contrast and the curl at the edge of the container is not seen. With the goal.

[0006]

According to the present invention, a gas barrier resin is used as a base layer (A1) having a melting point of 65 to 1 on its surface.
A laminated sheet in which a thermoplastic resin heat seal layer (A2) at 24 ° C. is laminated is thermoformed to store food in the food storage recess of a transparent food container (A) provided with a food storage recess,
Then, the opening of the food container is made of a synthetic paper (B1) having a opacity of 85% or more and a whiteness of 85% or more, which is made of a stretched product of a microporous propylene resin film containing an inorganic fine powder. And a gas barrier resin layer (B2, B2 ') made of a transparent stretched polyethylene terephthalate film is provided on the front and back surfaces of the base material layer, and the melting point of at least one surface of the gas barrier resin layer is 65-
124 ° C thermoplastic resin heat sealable resin layer (B3)
A sheet-like lid material (1) having a laminated structure in which printing (B4, B4 ') is provided between the synthetic paper (B1) and the gas barrier resin layer (B2, B2'). B), then the container heat seal layer (A
2) and the heat-sealing layer (B3) of the lid material are heat-sealed to seal the container, and the sealed food container is then heated to a temperature lower than the melting point of the propylene resin as the base resin of the synthetic paper (B1). The present invention provides a retort sterilized food package obtained by sterilizing with a retort kettle.

[0007]

[Function] Since opaque synthetic paper is used for the base material layer of the lid material,
The contents of the container are invisible from the product name, manufacturer, recipe, and lid material side where the design is printed, and the white contrast of the print and the synthetic paper (contrast) is excellent, making the print easy to read. In addition to the biaxially stretched polyethylene terephthalate film for the lid material, a microporous synthetic paper made of an inorganic filler-containing propylene resin stretched film is used, and the biaxially stretched polyethylene terephthalate film is used on both front and back surfaces of the synthetic paper. Since they were laminated, no curl was found on the flange of the container even after the retort sterilization treatment.

(Detailed Description of the Invention) Food Container (A ) The food container (A) having an excellent gas barrier property and having a see-through interior has a gas barrier resin as a base layer (A1) and a melting point of 65 to 124 on this surface. A transparent food container (A) having a food-accommodating recess formed by thermoforming a laminated sheet in which a thermoplastic resin heat-sealing layer (A2) at 0 ° C. is laminated.

Gas barrier resin (A1) Examples of the gas barrier resin include polyamides such as nylon 6, nylon 6,6, nylon 6,10 and nylon 12, ethylene content of 20 to 60 mol% and saponification degree of 90.
% Or more of saponified ethylene / vinyl acetate copolymer (ethylene / vinyl alcohol copolymer), polyethylene terephthalate, polyvinylidene chloride, etc., having an air permeability coefficient of 0 to 10 cc / m ² , 24 hours, atmospheric pressure, JIS Z- 0
Moisture permeability measured at 20 ° C by 208 is 0.1-4g /
m ² · 24 hours · atmospheric pressure is used.

Heat-sealable resin (A2) As the heat-sealable resin having a melting point of 65 to 124 ° C., ethylene / vinyl acetate copolymer, maleic anhydride-grafted ethylene / vinyl acetate copolymer, ethylene / acrylic acid Copolymer, ethylene / methacrylic acid copolymer,
Ethylene / acrylic acid lower alkyl ester copolymer,
Ethylene / methacrylic acid lower alkyl ester copolymer, low density polyethylene, linear low density polyethylene, Surlyn, etc. can be used.

Laminated sheet A laminated sheet comprises the above gas barrier resin (A1) and
The heat-sealable resin (A2) may be co-extruded to produce a laminated sheet, or the heat-sealable resin film may be melt-extruded and laminated on the surface of the gas barrier resin sheet. Since the gas barrier resin (A1) is expensive, polypropylene, propylene / ethylene copolymer, poly (4-methylpentene-1), propylene / ethylene / butene-1 copolymer, propylene / 3-methylpentene- An inexpensive and transparent polyolefin resin sheet (A3) such as 1-copolymer may be laminated to reduce the thickness of the gas barrier resin sheet A1.

When the adhesiveness between the gas barrier resin (A1) and the polyolefin is poor, the heat-sealable resin, polyether polyol / polyisocyanate, polyester polyol / polyisocyanate, polyethyleneimine or polyamine polyamide is provided between the two. The adhesive force between the two is increased by interposing a primer such as an epichlorohydrin adduct. The thickness of the laminated sheet is 0.3-2m
m, preferably 0.5 to 1 mm, and the wall thickness of the gas barrier resin is 5 μm to 1.98 mm, preferably 10
μm to 100 μm. The thickness of the heat-sealable resin layer is 5 to 80 μm, preferably 20 to 45 μm.
The thickness of the polyolefin resin layer is 0.27 to 1.95 m
m, preferably 0.3 to 0.9 mm. The thickness of both adhesive layers is 0.5 to 40 μm.

The container (A) is formed by subjecting the laminated sheet to thermoforming such as vacuum forming, pressure forming, and press forming, and is usually a flange because it facilitates heat fusion with the lid material. The structure is provided with a portion at the edge.

Lid material (B) Lid material (B) is an opacity (JI) made of a stretched product of a microporous propylene resin film containing an inorganic fine powder.
SP-8138) is 85% or more, whiteness (JIS L
-1015) is a synthetic resin (B1) having a base layer of 85% or more, and a gas barrier resin (B) made of transparent stretched polyethylene terephthalate film on the front and back surfaces of the base layer.
2, B2 ′) and a thermoplastic resin heat seal layer (B3) having a melting point of 65 to 124 ° C. on at least one surface of the gas barrier resin layer, and the thickness is 60 to 25.
It is a laminated film of 0 μm.

The synthetic paper (B1) is a microporous synthetic paper used for clarifying the printing and preventing curling of the container of the retort sterilized food package.
The opacity is 90% or more, preferably 93 to 100%, the whiteness is 85% or more, preferably 95 to 110%, and the porosity calculated by the following formula (1) is 10 to 60%, preferably Is 15 to 45%, the wall thickness is 30 to 300 μm, preferably 50 to 120 μm, and the density is 0.6 to 1.0 g / c.
It is a water-resistant synthetic paper comprising a propylene-based resin stretched film containing m ³ of inorganic fine powder.

[0016]

[Formula 1]

Examples of such microporous synthetic papers include the following, which are described in the above-mentioned patent publications. Biaxially stretched film of a microporous thermoplastic resin containing an inorganic fine powder or an organic filler in a proportion of 8 to 65% by weight (Japanese Patent Publication No. 54-31032, US Pat. No. 3).
775521, U.S. Pat. No. 4,191,719, U.S. Pat. No. 4,377,616, U.S. Pat. No. 4,560,614). The biaxially stretched propylene-based resin film containing 5 to 40% by weight of the inorganic fine powder was used as the base layer (1a), and the uniaxially stretched propylene resin film containing 8 to 65% by weight of the inorganic fine powder was used as the paper layer ( 1b) (refer to Japanese Patent Publication No. 46-40794, Japanese Patent Publication No. 57-149363, Japanese Patent Publication No. 57-181829, etc.).

This synthetic paper may have a two-layer structure or a three-layer structure in which a paper-like layer of a uniaxially stretched film exists on the front and back surfaces of a base material layer (Japanese Patent Publication No. 46-40794). 3 layers in which another resin film layer exists between the paper-like layer and the base material layer
Even with a seven-layer synthetic paper (Japanese Patent Publication No. 50-29738, Japanese Patent Publication No. 57-149363, Japanese Patent Publication No. 56-126155, Japanese Patent Publication No. 57-181829), the back side is made of ethylene / methyl acrylate. Polymer, ethylene / (meth) acrylic acid copolymer metal salt (Na, Li, Zn,
K), three or more layers of synthetic paper having a heat seal layer made of a resin having a melting point lower than that of the base layer resin such as chlorinated polyethylene may be used (Japanese Patent Publication No. 13973/1993).

In order to further improve the offset printability on the surface of the synthetic paper, polyethyleneimine, poly (ethyleneimine-urea), ethyleneimide adduct of polyamine polyamide, epichlorohydrin adduct of polyamine polyamide, tertiary to tertiary A water-soluble coating layer for improving printability selected from the group consisting of quaternary nitrogen-containing acrylic resins may be provided.

An example of a three-layer synthetic paper is a uniaxially oriented film obtained by unidirectionally stretching a thermoplastic resin film containing 5 to 40% by weight of inorganic fine powder at a temperature lower than the melting point of the resin. Inorganic fine powder on both sides of the film
A paper-like layer obtained by laminating a molten film of a thermoplastic resin containing 65% by weight and then stretching the laminated film in a direction perpendicular to the above-mentioned direction is uniaxially oriented and has many fine voids. It is a film, and the base material layer is a biaxially oriented laminated structure. Of course, a layer of the primer (coating agent) may be provided on this surface to further improve the offset printability, and the base layer (1a) of the biaxially stretched film provides the strength balance between the length and width of the synthetic paper. Uniaxially stretched film (1b, 1c) that contributes to the
Has a paper texture.

On the paper-like layer side of the above synthetic paper,
Synthetic paper with high gloss having a structure in which a transparent thermoplastic resin laminate layer having a wall thickness of 0.1 to 20 μm and containing no inorganic fine powder is provided (Japanese Patent Publication No. 60437/1992).
-60411, Japanese Patent Laid-Open No. 61-3748).
For example, a biaxially stretched film of a propylene-based resin is used as a base material layer (1a), and a surface layer (1b) and a back surface layer (1c) made of a uniaxially stretched film of a propylene-based resin containing 8 to 65% by weight of inorganic fine powder. Is used as a support, a transparent film layer of a thermoplastic resin containing no inorganic fine powder is provided on the surface layer (1b) side of the support, and a coating layer (1d) having an antistatic function is further provided. Prepared synthetic paper (Japanese Patent Laid-Open No. 61-3748) or a biaxially stretched film of a propylene-based resin film as a base material layer (1
a), a paper-like layer (1b) made of a uniaxially stretched film of a propylene-based resin containing an inorganic fine powder in a proportion of 8 to 65% by weight on at least one surface of the base material layer, and a uniaxial propylene-based resin film. A synthetic paper provided with a laminate with a surface layer (1d) made of a stretched film, wherein the surface layer (1d) has a wall thickness (t) of an average particle of inorganic fine powder present in the paper-like layer. A synthetic paper (Japanese Patent Publication No. 1-60411) comprising a multilayer resin film, which satisfies the following expression (2) when the diameter is (R).

[0022]

[Formula 2] R ≧ t ≧ 1/10 × R (2) The propylene-based resin used as the material of the synthetic paper contains propylene homopolymer and propylene as main components, and ethylene, butene-1, and hexene- Examples thereof include copolymers with α-olefins such as 1, pentene-1, octene-1, 4-methylpentene-1, and 3-methylpentene-1. The copolymer may be a random copolymer or a block copolymer.

In order to improve the stretchability, a resin having a melting point lower than that of polypropylene such as polyethylene, polystyrene and ethylene-vinyl acetate copolymer is used in the base layer 3 to 2.
It is preferable to add 5% by weight. Also, as inorganic fine powder, calcium carbonate, calcined clay, silica, diatomaceous earth,
Talc, titanium oxide, barium sulfate, etc., particle size 0.03
~ 16 microns are used. The stretching ratio is preferably 4 to 10 times in both the longitudinal and transverse directions, and the stretching temperature is 140 to 1
It is 62 ° C. The stretching speed is 50 to 350 m / min.

When the opacity of the synthetic paper is less than 90% and the whiteness is less than 85%, the appearance of printing is deteriorated. The synthetic paper has a wall thickness of 30 to 300 μm, preferably 50 to 120 μm
If it is less than 30 μm, it is difficult to stably manufacture synthetic paper, and if it exceeds 300 μm, there is no difference in curl prevention effect, and the cost of the lid material becomes high, which is economically disadvantageous. . The presence of minute voids (holes) in synthetic paper contributes to the improvement of the opacity of synthetic paper, but the presence of this void has a heat insulating effect, and the flange of the container is heated by heat sterilization in a retort kettle. It seems that this also contributes to the fact that the section does not curl.

Stretched polyethylene terephthalate film
(B2, B2 ') Stretched polyethylene terephthalate film (OPET)
Is transparent and usually available in the market with a thickness of 8 to 80 μm. Preferably, the thickness of 8 to 25 μm is economical. The stretching temperature of this film is about 100 to 130 ° C.
Is generally.

Heat-sealable layer (B3) The resin of the heat-sealable resin layer (B3) of the lid material that is fused with the heat-sealable resin layer (A2) of the container is described in the section of the heat-sealable resin layer of the container. The ones listed can be used.
The heat-sealable resin layer (B3) has a wall thickness of 5 to 50 μm.
m, preferably 20-40 μm.

Printing (B4) for printing the product name, manufacturer, recipe, design, etc.
It may be applied to synthetic paper or drawn polyethylene terephthalate film. The printing (B4 ') for improving the appearance of the contents may be performed on either side of the synthetic paper or OPET. This printing is solid printing such as yellow, orange, and ultramarine, and yellow / ultraviolet. Is printed in a striped pattern.

The laminate of the stretched polyethylene terephthalate film and the heat-sealable resin is obtained by melt-laminating the heat-sealable resin film on the stretched polyethylene terephthalate film at a temperature at which the stretched film does not shrink by heat or by bonding both films with a primer. Stack.

As the primer, a liquid polyisocyanate / polyether polyol such as EL-150 (trade name) or BLS-20 manufactured by Toyo Morton Co., Ltd.
A mixture of 80A and BLS-2080B is a polyisocyanate / polyester polyol such as AD of the same company.
-503 (trade name), and polyvinyl acetate aqueous emulsion, for example, MB-100 manufactured by Saiden Chemical Co., Ltd.
(Trade name), vinyl acetate / acrylic acid alkyl ester copolymer emulsion can be used. Lamination of synthetic paper and stretched polyethylene terephthalate film is performed using the above-mentioned primer. The coating amount of the primer is 0.1 to ²⁰ g / m ² , preferably 0.5 to 8 g / m ² in terms of solid content.
^{Is 2} .

Retort-sterilized food package As shown in FIG. 1, a hamburger, meatball processed food 3 and, if necessary, meat juice 4 are placed in a storage recess 2 of a container 1, and a lid material is placed in the opening of the container 1. 5 is guided so that the manufacturer, the product name, etc. are printed on the outside, and the heat-sealing resin layer side of the lid material is heated to 120 to 140 ° C. to be softened,
The container 1 and the lid member 5 are pressed by a roll, and the flange portion 6 of the container is pressed.
Heat fusion with. Then put this in the retort kettle,
The retort sterilized food package 7 of the present invention is obtained by heat sterilization at 110 to 140 ° C for 5 to 40 minutes.

[0031]

EXAMPLES The present invention will be described in more detail below with reference to examples. Production Example of Synthetic Paper (Example 1) (1) Melt Flow Rate (MFR) 0.8 g / 10
Min polypropylene (melting point about 164-167 ° C) 81% by weight, high-density polyethylene 3% by weight and average particle size 1.
The composition (A) containing 16% by weight of calcium carbonate of 5 μm was kneaded by an extruder set at a temperature of 270 ° C., extruded into a film, and further cooled by a cooling device to obtain an unstretched film. It was Then, this film was heated again to a temperature of 150 ° C., and then stretched 5 times in the longitudinal direction to obtain a 5 times longitudinally stretched film.

(2) A composition (B) prepared by mixing 54% by weight of polypropylene having an MFR of 4 g / 10 min (melting point: about 164-167 ° C.) and 46% by weight of calcium carbonate having an average particle size of 1.5 μm is separated. After kneading at 210 ° C. with an extruder of No. 3, the film was extruded with a die and laminated on both sides of the 5 × longitudinally stretched film obtained in the above step (1) to form a three-layer structure. I got a film. Next, after cooling the laminated film having the three-layer structure to a temperature of 60 ° C., it is heated again to a temperature of about 155 ° C. and stretched 7.5 times in the transverse direction using a tenter, and then at a temperature of 165 ° C. Annealed, cooled to a temperature of 60 ° C, slits in the ears, three-layer structure (uniaxial stretching / biaxial stretching / uniaxial stretching)
Thickness of 60 μm (B / A / B = 15 μm / 30 μm / 1
5 μm) laminated film, porosity 33%, density 0.7
A multi-layer synthetic paper having 8 g / cm ³ , whiteness of 85%, opacity of 91% and breaking strength of 7 kg / cm ² was obtained.

After subjecting the surface of this three-layer laminated film to corona discharge treatment, an aqueous coating solution containing the following antistatic agents (a) and (a) was applied to both surfaces at a solid content of 0.05 g / side.
m ² (wall thickness of about 0.1 μm) was applied, dried and wound. The composition of the coating agent aqueous solution is as follows.

(A) "Antistatic agent" manufactured by Mitsubishi Petrochemical Co., Ltd.
Acrylic resin aqueous solution "ST-1100" (trade name)
[The following group (1) is included in the molecular chain]: 100 parts by weight

[Chemical 1] (A) Water-soluble polyamine polyamide epichlorohydrin adduct (Tik Hercules "Kaymen 5"
57H ": 25 parts by weight The coating material layer of the obtained synthetic paper had a gloss of 15% and a Bekk smoothness of 680 seconds.

Example 2 (1) Melt flow rate (MFR) 4.0 g / 10
55% by weight of polypropylene (melting point of about 164-167 ° C.), 25% by weight of high-density polyethylene, and 20% by weight of calcium carbonate having an average particle size of 1.5 μm are mixed, and the composition (A) is set at a temperature of 270 ° C. After kneading with the extruder, the film was extruded into a film and further cooled by a cooling device to obtain an unstretched film. (2) Then, this film was heated again to a temperature of 150 ° C., and then stretched 5 times in the longitudinal direction to obtain a 5 times longitudinally stretched film.

Next, the film was heated again to a temperature of 155 ° C., stretched 7.5 times in the transverse direction using a tenter, and annealed at a temperature of 165 ° C. to obtain 60.
Cool to a temperature of ℃, slit the ears and make the density 0.
88g / cm ³ , opacity 86%, burst strength 3kg / c
A microporous film made of a biaxially stretched film having a wall thickness of m ² of 45 μm and a porosity of 37% was obtained. After the surface of this biaxially stretched film was subjected to corona discharge treatment, an aqueous solution of coating agent was applied to both surfaces in a solid content of 0.05 g / m ² on one side (thickness of about 0.1 μm).
It was applied and dried so that

The composition of the above coating agent aqueous solution was as follows. (A) "Antistatic agent" manufactured by Mitsubishi Yuka Co., Ltd. Acrylic resin aqueous solution "ST-1100": 100 parts by weight (B) Epichlorohydrin adduct of water-soluble polyamine polyamide ("Kamen 5 manufactured by Tick Hercules")
57H ": 25 parts by weight The coating material layer of the obtained synthetic paper had a glossiness of 33% and a Beck's smoothness of 3800 seconds.

(Example 1) (Molding of container) Propylene homopolymer (melting point: about 168)
C.), maleic anhydride-grafted polypropylene (Modic manufactured by Mitsubishi Yuka; trade name), polyethylene terephthalate (melting point about 234.degree. C.) and ethylene content of 95.degree.
6 wt% ethylene-vinyl acetate copolymer (melting point about 88
C.) and melt-kneaded in separate extruders, each of which is supplied to one co-extrusion die and laminated, and then co-extruded into a sheet shape, which is cooled and polypropylene (PP) 0.6 m
m, Modic 20 μm, PET 20 μm, ethylene / vinyl acetate copolymer (EVA) 25 μm, transparent (haze 4.8%) laminated sheet (PP / Modic / PE
T / EVA; total thickness 665 μm) was obtained. This laminated sheet was heated to about 260 ° C. and vacuum-formed to obtain a container having a storage recess (depth 2 cm) and a flange (5 mm width).

(Manufacture of lid material) The synthetic paper obtained in Example 1 was subjected to multicolor gravure printing on the surface of the manufacturer, trade name, recipe and hamburger, and solid printing was performed on the back surface with yellow gravure printing ink. A polyurethane anchor coating agent "BLS-" from Toyo Morton Co., Ltd. is used as a primer on both of these printed surfaces.
An adhesive mixture of "2080A" and "BLS-2080B" was applied at 2 g / m ² (ratio of solid content), and then ethylene / vinyl acetate copolymer (melting point: about 90) was applied to this one side.
C.) Biaxially oriented polyethylene terephthalate film (OPET; laminated with film (thickness 30 μm))
A biaxially stretched polyethylene terephthalate film (12) having a thickness of 12 μm on the solid printing side with the OPET side being the primer side and on the other primer surface.
(μm) was adhered to obtain a lid material having a wall thickness of about 118 μm.

(Manufacture of Package) The processed meat hamburger is placed in the container, and after pouring the meat juice, the opening of the container is closed with a lid material heated to 125 ° C., and the lid material is pressed with a roll. Pressing was performed to fuse the container and the lid material. This was placed in a retort kettle and heat-sterilized at 125 ° C. for 30 minutes to obtain a retort-sterilized food package. No curl was found at the flange portion of the container (0.1 mm or less), and the container was not deformed.

Example 2 Instead of the synthetic paper of Example 1, Example 2 is used.
A retort sterilized food package was obtained in the same manner as in Example 1 except that the above synthetic paper was used. The curl of this container was as small as about 0.5 mm, which was not a problem compared with the conventional product having a curl of 2 to 3 mm.

(Examples 3 to 4) A retort was prepared in the same manner as in Example 1 except that ethylene (about 22 mol%) / vinyl alcohol copolymer or nylon 6 was used in place of the polyethylene terephthalate used in the container. A sterilized food container was obtained. The performance of the obtained food container is shown in Example 1.
It did not change.

[0043]

In the food package of the present invention, since the lid is opaque, the contents cannot be seen through from the lid side, and the letters and patterns printed on the lid can be seen clearly. Further, no conventional curl is found in the flange portion of the retort-sterilized container.

[Brief description of drawings]

FIG. 1 is a lid material and a container according to the present invention.

FIG. 2 is a conventional retort sterilization-treated food package curled toward the lid side.

FIG. 3 is a manufacturing process diagram of a retort-sterilized food package of the present invention.

[Explanation of symbols]

A Food container A1 Gas barrier resin base layer A2 Heat seal layer B Lid material B1 Synthetic paper base material layer B2 Gas barrier resin layer B2 'Same as above B3 Heat sealable resin layer B4 Printing B4' Same as above b Cover material b1 Polypropylene film b2 Adhesive layer b3 Biaxially oriented polyethylene terephthalate film (OPET) b4 Heat seal layer

Claims (1)

[Claims] 1. A laminated sheet in which a gas barrier resin is used as a base layer (A1) and a thermoplastic resin heat seal layer (A2) having a melting point of 65 to 124 ° C. is laminated on the surface of the base layer (A1) is thermoformed to provide a food accommodating recess. The transparent food container (A) has a transparent food container in which the food is stored, and the opening of the food container has an opacity of a stretched product of a microporous propylene-based resin film containing inorganic fine powder. Of 85% or more and a whiteness of 85% or more as a base material layer, and a gas barrier resin layer (B which is made of a transparent stretched polyethylene terephthalate film on the front and back surfaces of the base material layer (B).
2, B2 ') and a thermoplastic resin heat-sealing resin layer (B3) having a melting point of 65 to 124 ° C on at least one surface of the gas barrier resin layer, Printing (B4, B) is performed between the synthetic paper (B1) and the gas barrier resin layer (B2, B2 '), respectively.
4 ') is closed with a sheet-like lid material (B) having a laminated structure, and then the heat-sealing layer (A2) of the container and the heat-sealing layer (B3) of the lid material are heat-sealed to hermetically seal the container. Then
Then, the sealed food container is sterilized using a retort kettle at a temperature lower than the melting point of the propylene-based resin as the base resin of the synthetic paper (B1) to obtain a retort-sterilized food package.