JPH0213412A - Food packaging receptacle capable of cooking in oven-toaster - Google Patents

Abstract

PURPOSE:To keep scorched cooked food from adhering to a receptacle and to keep good flavor by using coating material formed by dispersing polyolefine in thermosetting resin coating material to form a protective coat on the inner surface of a receptacle main body. CONSTITUTION:A packaging receptacle comprises a receptacle main body 1 and a cover 2. The receptacle main body 1 comprises a tapered cylindrical drum wall portion 3A formed by drawing of stacked or coated sheet 5, the base portion 3B connected to the lower end of the drum wall portion and a flange portion 4 connected to the upper end of the drum wall portion. The sheet 5 comprises a metal foil 6, an inner coating layer 7 applied to the surface of the metal foil, that becomes the receptacle inside and an outer coating protective layer 8 applied to the surface of the metal foil that becomes the receptacle outside. The inner coating layer 7 is formed by thermosetting resin coat in which polyolefine denaturated with acid dispersed. As the thermosetting resin coating material, material having the thermosetting temperature within the range of 90-130 deg.C is used. The outer coating protective layer 8 may be film of thermosetting resin or thermoplastic resin.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application) The present invention relates to a toastable packaging container, and more specifically, the present invention relates to a toasterable packaging container, and more specifically, the present invention relates to a toasterable packaging container. Pre-cooked food does not stick to the container wall,
It also relates to a toastable packaging container that retains good flavor.

(Prior Art and its Problems) Recently, so-called toaster packaging containers, in which the packaging container and the food contents are placed in a toaster oven and cooked, have come into wide use.

This conventionally known toasterable packaging container is a metal container made of aluminum or the like filled with the food content.In this type of container, when cooked in a toaster oven, the food will not burn. There is a problem with cooked food sticking to the walls of the container.

In order to avoid this problem, it is possible to provide a protective coating consisting of a thermosetting resin coating on the inner surface of the container body, but it is not possible to effectively avoid the problem of burnt cooked food. In this case, a new problem arises in that the flavor characteristics deteriorate due to softening of the coating film and generation of decomposition products during cooking.

(Means for Solving the Problems) The present invention solves the above-mentioned problems by forming a protective coating on the inner surface using a paint in which acid-modified polyolefin is dispersed in a certain thermosetting resin paint. This is what I did.

That is, according to the present invention, there is provided a container formed by heat-sealing a "Francy" container body formed by drawing a metal foil sheet and a lid body at the flange portion, the container body including the flange. 1.-Stable packaging, characterized in that the entire inner surface is provided with an inner surface protective coating formed from a coating in which acid-modified polyolefin is dispersed in a thermosetting resin coating with a heat softening temperature of 90 to 130 degrees Celsius. container or provided.

(Function) As described above, according to the present invention, an oven tote coating film is formed by forming an internal protective coating using a coating material in which an acid-modified polyolefin is blended and dispersed in a thermosetting resin coating.
Star cooking also achieves the significant advantage that burnt cooked food does not stick to the walls of the container.

The reason why such advantages are achieved in the present invention is not clear, or it is presumed as follows.

That is, acid-modified polyolefin has a lower density than thermosetting resin, so when a protective coating is formed, the acid-modified polyolefin is held floating on the surface of the coating, and this floating It is thought that the lubricating effect of the acid-modified polyolefin prevents the roasted boar and 7A raw food from adhering to the container wall surface.

In addition, in the present invention, since acid-modified polyolefin is blended into the paint, this inner surface protective coating is not applied to the entire inner surface of the container, that is, the container flange, thereby creating a special heat-sealable resin layer. It becomes possible to perform heat sealing with the lid body without causing any damage.

Furthermore, due to the surfactant action of acid-modified polyolefin itself,
The wettability of the paint is improved, and when the paint is applied to the inner surface of a container, it becomes possible to form a uniform protective coating in which pinholes are effectively suppressed. Moreover, the presence of such a protective coating improves the lubricity and effectively suppresses seizure, abrasion, etc. when forming the container body by drawing.

In the present invention, it is also important to use a thermosetting resin paint having a heat softening temperature in the range of 90 to 130°C as the paint in which the acid-modified polypropylene is dispersed.

That is, since a toaster oven does not have a temperature adjustment mechanism, when cooking is performed, the container may be heated to an extremely high temperature. For example, in the case of content food or gratin, when this gratin is cooked,
The temperature of the container flange reaches approximately 220°C.

Therefore, if a thermosetting resin paint with a heat softening temperature lower than 90° C. is used, the paint film will soften during cooking and thermal decomposition products will be generated, which will significantly impair the flavor of the food contents.

Further, if the heat softening temperature exceeds 130° C., the protective coating film becomes too hard, making drawing forming difficult.

This thermal softening temperature is measured by a penetration heating method using a thermal yJ and mechanical analyzer (TM8), as shown in the examples below.

(Preferred Embodiment of the Invention) Packaging Container In FIG. 1 showing an example of the packaging container of the present invention, this packaging container consists of a container body 1 and a lid 2. As shown in FIG. Container body 1
The body wall portion 3A is formed by laminating or drawing forming a covering sheet as described below, and is made up of a tapered or cylindrical body wall portion 3A, a bottom portion 3B continuous to the lower end of the body wall portion, and a flange portion 4 continuous to the top end of the body wall portion. There is. In FIG. 2 showing the cross-sectional structure of the container body sheet, this sheet 5 includes a metal foil 6, an inner coating layer 7 applied to the surface of the metal foil that will become the inner surface of the container, and an outer surface applied to the surface of the metal foil that will become the outer surface of the container. It consists of a covering protective layer 8.

In the present invention, as already mentioned, the inner surface coating layer 7 is composed of a thermosetting resin coating containing an acid-modified olefin resin.

On the other hand, the lid body 2 is composed of a laminate as described below, has approximately the same dimensions and shape as the outer circumference of the flange portion of the container body, and has a heat-sealed portion between it and the flange portion 4. 9 is formed. In FIG. 3 showing the cross-sectional structure of the laminate that constitutes the lid 2, the laminate 1
0 is formed by a base N1'1 made of metal foil or the like, an inner surface material layer 12 provided on the innermost side of the container of the base 11, and an outer protective layer 13 provided on the outer surface of the base layer 11. Container body The metal foil that makes up the container body is aluminum foil.
Light metal foils such as ゛, steel foils or iron foils, or surface-treated steel foils such as tin foil, chromic acid treated steel foil, electrolytic chromic acid treated steel foil, nickel plated steel foil, nickel/tin plated steel foil, etc. are used. Ru. These metal foils generally have a thickness of 0.3 to 0.0
It is preferable to have a thickness of 2 mm, especially 0.2 to 0.05 mm.

An inner coating layer 7 and an outer coating layer 8 are provided on the inner and outer surfaces of this metal foil, respectively, to form a coated metal foil sheet, and the sheet is subjected to a drawing process known per se, and if necessary,
Obtained by curling the outer periphery of the flange. The drawing process can be carried out using any combination of a male die and a die (female die).
If the tool described in the publication is used and the method described in Japanese Patent Publication No. 57-4408 is carried out, the franchise of the trunk wall section can be obtained.
This is preferable because it can prevent wrinkles from forming near the roots.

Inner Coating Layer 7 In the present invention, the inner coating layer 7 provided on the inner surface of the container of the metal foil 6 is made of a thermosetting resin coating film in which acid-modified polyolefin is dispersed, as described above.

As the acid-modified olefin resin, a resin obtained by graft-modifying an otnofin resin with an ethylenically unsaturated carboxylic acid or its anhydride is used. Examples of the olefin resin backbone polymer include low-medium density polyethylene or high-density polyethylene, linear low-density polyethylene, homopolypropylene, crystalline propylene-ethylene copolymer, polybutene-1, polybentene-1, butene-1/propylene copolymer. Examples include a butene-1/propylene/engineered ethylene terpolymer and the like. From the point of view of retort resistance, homopolypropylene is suitable. Examples of ethylenically unsaturated carboxylic acids and their anhydrides include acrylic acid, methacrylic acid, maleic acid, fumaric acid, crotonic acid, itaconic acid, citraconic acid, 5-norbornene-2,3-dicarboxylic acid, maleic anhydride, and anhydride. citraconic acid, 5-norbornene-2,
3-dicarboxylic anhydride, tetrahydrophthalic anhydride, etc. may be mentioned, but maleic anhydride is most suitable in terms of heat sealability. The acid-modified olefin resin used is 001 to 60 milliequivalents/100 g resin, especially 10 to 20
It is preferable to contain the resin at a concentration of 0 mm/100 g resin.

In the present invention, maleic anhydride-modified propylene resin is most preferably used.

As the thermosetting resin paint containing the above-mentioned acid-modified polyolefin, one having a heat softening temperature in the range of 90 to 130 IC, particularly 95 to 120 °C is used, and as long as the heat softening temperature is within this range, Thermosetting resin coatings known per se are used.

For example, epoxy resin, phenolic resin, epoxy-phenolic resin, polyimide resin, urea resin, melamine resin, unsaturated polyester resin, diallyl phthalate resin, epoxy acrylate resin, urethane resin, xylene resin, thermosetting acrylic resin, etc. These can be used alone or in combination of two or more.

In the present invention, epoxy-phenol resins are particularly preferred.

Examples of the epoxy-phenol paint include paints containing an epoxy resin derived from hisphenols and shrimp herrohydrin and a resol type phenol aldehyde resin. The epoxy resin used has an epoxy equivalent of 2-000 to 6,000, particularly 2,500 to 4.
500 is appropriate. As a phenolic resin,
Average molecular weight is 200 to 800, especially 250 to 600
The number of methylol groups or etherified methylol groups per phenol ring is from 0.3 to 10, especially from 0.4 to 10.
It has excellent adhesion to metal foil, workability, and corrosion resistance. Phenols used in the production of phenolic resins include, for example, trifunctional phenol necks such as carbolic acid, p
-Cresol, 0-cresol, p-ethylphenol, bifunctional phenols such as p-butylphenol, polyhydric phenols such as bisphenol A, bisphenol F, etc., or a combination of 2fffi or more may be used. Epoxy resin components and phenolic resin components are generally 505
It is preferably present in a weight ratio of 0 to 90.0, particularly 60,140 to 9,010.

The inner surface protective coating film, that is, the inner surface coating layer 7, is made by dispersing acid-modified olefin resin in the above-mentioned thermosetting resin coating solution.
It is formed by applying this paint onto metal foil and baking it. Baking of paint film is usually 180 to 250℃
This can be done in 30 seconds to 10 minutes.

The thickness of this inner surface protective coating is generally desirably in the range of 2 to 30 μm, particularly 5 to 20 μm.

In addition, in the present invention, the amount of acid-modified polyolefin blended in the thermosetting resin paint is determined by the following formula, where L represents the thickness (μm) of the inner surface protective coating, and X represents the thermosetting resin. It is the number of parts by weight of the acid-modified polyolefin per 100 parts by weight, and d is the density of the thermosetting resin (g
/cm3), and d2 is the density (g/ctn3) of the acid-modified polyolefin.The blending amount is such that the coverage (A) defined by the following is satisfied in the range of 05 to 20, especially 08 to 15. This is desirable.

That is, if this coverage (1> is less than 05),
Since the amount of acid-modified polyolefin is small, the amount of acid-modified polyolefin floating on the surface of the protective coating is reduced, making it possible to achieve the objective of the present invention, which is to prevent baked cooked food from adhering to the container wall. It becomes difficult. Furthermore, it becomes difficult to effectively seal the lid.

In addition, when the coverage (f!,) exceeds 20, the amount of acid-modified polyolefin blended is too large, and the modified polyolefin that floats tends to melt during cooking, causing problems such as stickiness on the container wall. Furthermore, a problem arises in that the flavor of the cooked food is reduced.

Outer coating layer 8 The protective coating provided on the outer surface of the metal foil is made of, for example, phenol.
Formaldehyde resin, urea/polmaldehyde resin,
Thermosetting resin consisting of melamine/formaldehyde resin, xylene/formaldehyde resin, epoxy resin, alkyd resin, polyester resin, thermosetting acrylic resin, urethane phase 1 resin alone or in combination of two or more, or acrylic resin, hinyl chloride-acetic acid A coating film of a thermoplastic resin such as vinyl copolymer, vinyl chloride-vinyl acetate maleic acid copolymer, vinyl resin such as vinyl butyral resin, styrene-butacyene-acrylic acid ester copolymer, polyamide resin, etc. good.

5-The base body 1 of the cover body is the metal foil mentioned above, 20'! Thermoplastic resin films such as stretched polyethylene terephthalate film, biaxially stretched nylon film, and polycarbonate film, various papers; or laminates of two or more of these are used, and the inner surface material 12 is applied to this to form the lid.

As the inner surface material layer 12, a thermoplastic polyolefin resin of the same kind as the above-mentioned acid-modified polyolefin or a blend thereof is used, thereby forming an inner surface protective coating film (inner surface coating layer 7) also formed on the container flange portion 4. A strong heat-seal bond can be formed between the two.

The thickness of this inner material layer 12 is generally 3 to 100 μm,
In particular, it is desirable that the thickness be in the range of 5 to 40 μm.

Further, the base body 11 and the inner surface material 12 can be easily joined or laminated by using the acid-modified olefin resin or urethane adhesive described above.

As the outer surface protective wave N13 of the lid body, the paint mentioned above for the container body, various resin films, etc. are used.

In the packaging container of the present invention, after filling the container body with the contents and carrying out operations such as nitrogen replacement and water vapor replacement as necessary, a lid is applied to the container flange, and a heat seal bar and high frequency Heat-seal at a temperature of 170 to 250°C using heat-sealing means such as conductive heating or ultrasonic irradiation,
Perform sealing. If necessary, the sealed packaging container is sterilized at a temperature of 100 to 135° C. for 10 to 60 minutes to form a package that can withstand storage.

This package is placed in the oven i-star as it is, and the contents are heated and cooked.

(Effects of the Invention) According to the present invention, a protective coating is formed on the entire inner surface of the container body using a coating material made by blending an acid-modified polyolefin into a thermosetting resin coating having a softening temperature in the range of 90 to 130 t. By forming this, even when cooking in a toaster oven, the cooked food will not stick to the container wall.
The flavor of cooked foods is also effectively preserved.

The packaging container of the present invention is extremely effective as a toasterable packaging container for heating foods such as gratin, stew, curry, etc. in a toaster oven.

(Examples) Example 1 A yellow epoxyphenol paint was applied to one side of a 75 μm thick rolled #4 foil having a chromate surface IA buried layer on both sides at a coating amount of 65 mg/dm2.

Next, on the other side, an epoxyphenol paint (specific gravity d+ = 1.20 g/cm3) containing a bisphenol A type epoxy resin and a resol type phenol/formaldehyde resin consisting of a binuclear component at a weight ratio of 8020 (specific gravity d+ = 1.20 g/cm3) 1
Powder (specific gravity d 2
= 0.90g/cm3) 6 parts by weight (5,66wt
%) and baked at 230°C for 40 seconds (-1 digit. The coating amount after single coating was 1
05mg/dm2.

The thermal softening temperature of the obtained inner surface coating film was measured using a thermomechanical analyzer (T
As measured by the penetration method of MA), 1
The temperature was 10°C.

In addition, the coverage degree °C of the obtained inner surface coating film is expressed by the formula U-L /
It was calculated as (1+100·d2/x'd+) and found to be 6.6. (However, L=89 μm, d+
-1,20g/cIn3, d2= 0.90g/am3
) The thus obtained material was punched into a blank with a blank diameter of φ135 mm, and by a drawing method using an elastic punch, a corner with a height of 25 mm, an outer diameter of 83 mm, an inner diameter of 70 mm, a corner radius of 25 mm, and a flange portion curled outward. A mold container was molded.

In addition, as a lid material, we used a laminate base material of 12 μm PET/15 μm biaxially stretched nylon/20 μm aluminum foil and a thickness of 30 μm.
It consists of a μm thick ethylene-propylene copolymer support layer and a 5 μm thick blend layer of 70 wt% polypropylene and 30 wt% low density polyethylene. 10 μm ethylene-propylene copolymer 15 μm between coextruded film
A laminate with a PP-LDPE blend layer as a sealing layer is created by co-extruding two layers of maleic anhydride-modified polypropylene (modified PP or aluminum foil side) to perform sun lamination and then heat-treating in an oven. I got it. A lid with a size of 85 mm x 85 mm and having an opening knob at a part of the corner was punched out from this laminate.

Next, macaroni gratin was filled into the rectangular molded container, and the lid material was heat-sealed. This sealed container is 120
Retort sterilization was performed at ℃ for 30 minutes. The heat seal strength between the container body and the lid after retort sterilization was measured and found to be 2.5 kg/15 n1m. Also,
When the lid 2 was opened from the opening knob, the beer could be easily peeled off.

Further, the container was opened, the lid was removed, and the main body of the container containing macaroni gratin was heated in an 890 W toaster oven for 7 minutes. When the container was removed from the toaster oven, the macaroni gratin had a moderate amount of fish eyes. When I tried this macaroni gratin, it was cooked to the center and was very delicious. On the other hand, no changes such as discoloration were observed in the flange of the container body, where the temperature rises the most during heating in a toaster oven. In addition, when we investigated whether the macaroni gratin was scorched on the inner surface of the container body, no scorching was found.

Moreover, no strange odor was generated from the container body while the macaroni gratin was being heated in a toaster oven. Further, no off-taste or odor was observed in the macaroni gratin after heating.

Examples 2 to 7, Comparative Examples 1 to 3 Macaroni gratin filling using the thermosetting resin of the modified polypropylene-added thermosetting paint used for coating the inner surface of the container body in Example 1 as shown in Table 1. Samples were prepared and examined for the presence or absence of off-odor when heated in a toaster oven, and the presence or absence of off-taste and odor in macaroni gratin after heating.

In addition, the KMnO4 consumption of the container inner material, which is closely related to the flavor characteristics of the contents, was measured (measurement method according to the operation of Ministry of Health and Welfare Notification No. 20).

The above results are shown in Table 1.

1. In the case of resins with a high thermal softening temperature corresponding to the glass transition point, as in Examples 2 to 7, there was no occurrence of any off-odor when heated in a toaster oven, and no off-taste or odor was transferred to the macaroni gratin after heating. I hadn't. Furthermore, KMnO4 consumption was also at a low level.

On the other hand, when the epoxy acrylic resin had a high acrylic content and a low heat softening temperature, as in Comparative Example 1, a strange odor was generated when heated in a toaster oven. In addition, the polyester-based and vinyl chloride-based products of Comparative Examples 2 and 3 also had low heat softening temperatures, and generation of off-flavors was observed.

Examples 8 to 10, Comparative Examples 4 to 5 In Example 1, only the amount of maleic anhydride-modified PP added to the modified polypropylene-added epoxy phenol paint used for coating the inner surface of the container body was changed as shown in Table 2, and coating Samples and samples with different properties (fl) were prepared, and the KM of the inner surface material of the container, which is closely related to the heat seal strength after retort processing and the flavor characteristics of the contents, was prepared.
nO,+ consumption amount (measurement method according to the operation of Ministry of Health and Welfare Notification No. 20) was measured. The results are shown in Table 2.

When the degree of coverage p was small as in Comparative Example 4, the heat sealing strength was low and it was unbeatable as a sealed container. Further, when the degree of coverage was too high as in Comparative Example 5, the amount of KMnO4 consumed was large and the flavor of the contents tended to deteriorate.

Examples 11 to 14 Container bodies as shown in Table 3 were produced in the same manner as in Example 1.

In addition, a lid material as shown in Table 4 was prepared by the same method as in Example 1, and after filling with the contents shown in Table 4,
Tort treatment was carried out under the conditions shown in the table. In all cases, there was no change in the container at all due to the retort I-Suri, and the sealability was perfect. The heat seal strength after retort treatment was measured and was 2.5 kg 715 mm as shown in Table 4.
It was possible to open the package by peeling off the beer.

Furthermore, when the container was opened, the lid was removed, and the container containing the contents was heated in a toaster oven for 7 minutes, no abnormal odor was observed. Furthermore, no transfer of any off-taste or odor was observed in the contents after heating.

Table 2

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an example of a toastable packaging container of the present invention, FIG. 2 is a sectional view showing an example of a container body sheet of the present invention, and FIG. 3 is a perspective view showing an example of a lid body of the present invention. It is a sectional view of the laminate, in which reference numeral 1 is the container body, 2 is the lid, 3A is the body wall, and 3B is the sectional view of the laminate.
4 is the bottom, 4 is the flange, 5 is the container body sheet, 6 is the metal foil, 7 is the inner coating layer, 8 is the outer coating protective layer, 9 is the heat sealing portion, 10 is the laminate constituting the lid, 11 is the The base body, 12 is an inner surface material layer, and 13 is an outer surface protective layer.

Claims (2)

[Claims] (1) A container formed by heat-sealing a flange-equipped container body formed by drawing a metal foil sheet and a lid body at the flange portion, wherein the container body has a flange formed on the entire inner surface including the flange. 1. A toastable packaging container comprising an inner surface protective coating formed from a thermosetting resin coating having a heat softening temperature of 90 to 130° C. and an acid-modified polyolefin dispersed therein. (2) The above-mentioned inner surface protective coating has a formula, ▲mathematical formula, chemical formula, table, etc.▼ In the formula, L represents the thickness (μm) of the inner surface protective coating, and x represents the thickness per 100 parts by weight of thermosetting resin. It is the number of parts by weight of the acid-modified polyolefin, and d_1 is the density of the thermosetting resin (
g/cm^3), and d_2 is the density (g/cm^3) of the acid-modified polyolefin.It is characterized by having a coverage (l) in the range of 0.5 to 20. The toastable packaging container according to claim 1.