JPS591346A - Composite vessel for retort food - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] The present invention relates to a composite container for retort foods such as fruit jelly, coffee jelly, dessert foods such as perennial cans, and canned foods, which has excellent durability and a beautiful appearance. Moreover, it is an object of the present invention to provide a rigid container that is particularly useful for dessert foods that are enjoyed as a luxury item.

Conventionally, retort food containers have been made of thermoplastic resins with gas barrier properties, such as polyethylene terephthalate films, laminated with sheets of low-melting point resin films, or with aluminum foil laminated in order to impart heat-sealing properties. A bag-like product made from a sheet is used. However, since these bag-like products lack rigidity, they can currently only be used to package retort pouch foods such as instant curry and soup. Furthermore, since it does not easily change shape, it is not suitable for packaging foods that require rigidity and fashionability, such as dessert foods that require retort sterilization.

Therefore, containers made of aluminum and containers made of tin are currently the mainstream packaging containers for the above-mentioned dessert foods.

However, aluminum containers are not only difficult to print on, but also have poor impact resistance and are easily dented.

On the other hand, tin containers only require simple printing, and
The disadvantage is that the material cost is high.0 To obtain a cup-shaped container with elaborate multicolor printing on the outside, it is necessary to apply multicolor printing such as offset printing on the outside of a pre-formed container. Simply attach the blanks with adhesive. However, in a retort container, after the contents are filled into the container and the container is covered, H (1 to 1
Because it is sterilized at 30°C and then cooled with water spray, the blank often swells or peels off from the container body during sterilization and cooling, so it is difficult to use this conventional method for retort containers. is of little practical use.

The present inventors fixed a thermoplastic resin film such as polyvinyl chloride, polypropylene, polyethylene, etc. printed with letters and designs in a mold by electrostatic adhesion or reduced pressure, which was conventionally practiced, and then A method for producing a thermoplastic synthetic resin molded product by bringing a melt of thermoplastic resin of the same material as the film into contact with the film under pressure or reduced pressure, cooling the melt, and pasting or painting a blank ( Special Public Show 2
No. 8-5036, No. 38-26119, No. 4 (1-1
No. 2988, No. 46-9959, No. 48-12865
We focused on the fact that the adhesion between the blank and the container body is strong, and that the material of the blank is made of highly water-resistant thermoplastic resin film. When applied to a retort container for this purpose, the following problem was discovered.

■ In conventional blank pasting methods (including labels), the blank material and the molding resin for hollow, injection, etc. are the same resin, so the blank melts during molding, and the printed characters and designs are distorted. It is often blurred and unclear. Conventional blank film printing is done by gravure printing or flexographic printing, and these printing methods can only print large and simple designs and letters, so the overall printing is slightly blurred due to melting of the blank during molding. The actual situation was that it was overlooked as there was no practical problem.

Therefore, it is desired to develop a plastic blank that can be printed with delicate letters and patterns in multiple colors and that can be attached during molding.

(2) The resin forming the container body is a thermoplastic resin with excellent gas barrier properties, such as polycarbonate, polyethylene terephthalate, etc., but if these are used alone, the cost of the container increases.

As a method to solve the above drawback (2), it is conceivable to use, for example, a thermoplastic resin film that can be subjected to offset printing as the blank material. Offset printing is useful as a printing technology because it allows delicate characters and patterns to be printed in multiple colors, but it has the disadvantage that it cannot be applied to conventional plastic films.

Recently, a paper-like layer made of a stretched film of an inorganic filler-containing polypropylene film or a polyethylene film that has been proposed or commercially available as a synthetic paper (Tokukosho, 16-
4 (No. 1794, No. 54-31 (13 (No. 1), British Patent No. 109 (see each publication of No. 1059) includes synthetic paper that can be offset printed.

This offset printable synthetic paper is fixed in a mold as a blank, and the same material resin as the blank is used for blow molding, pressure molding, etc. at a pressure of 1-8 Kg/
When crA is subjected to low-pressure molding, the blank shrinks during molding and wrinkles occur, resulting in only defective products. This is because the label is a stretched film, so the external stress memorized during stretching becomes shrinkage stress, and when it comes into contact with molten resin during blow molding or other molding, the heat causes the blank to shrink.

The present inventors manufactured various blanks in order to prevent the occurrence of wrinkles when using this stretched film as a blank material, and as a result of studying the method of attaching the blanks, the inventors found that polypropylene containing an inorganic filler was used. A blank consisting of a composite sheet containing a paper-like stretched film of the above as a paper-like layer and at least a small amount of a thermoplastic resin film having a melting point lower than the melting point of the polypropylene by 15°C or more as a back layer, and a sheet forming a container body. It has been found that the generation of wrinkles can be prevented by using a composite sheet having a thermoplastic resin film with a relatively low melting point as the back layer, and by bonding the blank to the container body using vacuum pressure.

The above-mentioned problem (2) can be solved by using a composite sheet of polypropylene, which has heat resistance and rigidity, and a gas barrier resin as a molding sheet in order to reduce the amount of expensive gas barrier resin used.

That is, in this invention, a stretched polypropylene film containing 8 to 65% by weight of inorganic fine powder with offset printing on the surface is used as a paper-like layer, and the polypropylene forming the surface opposite to the paper-like layer is used as a paper-like layer. 1 than the melting point of
Wall thickness l-go of thermoplastic resin having a melting point lower than 5°C
A 1 micron blank is inserted into the mold so that the paper-like layer side of the blank is in contact with the mold, and then the on top of the mold, at least (a) a polypropylene base film, and (b) a resin film with low gas permeability selected from polyamide, polyester, saponified ethylene/vinyl acetate copolymer, and polyvinylidene chloride. and (C) a back layer made of a thermoplastic resin film having a melting point 15° C. or more lower than the melting point of the polypropylene and compatible with the thermoplastic resin constituting the back layer of the blank. This was obtained by supplying a melt of a composite sheet for use with the back layer side facing a mold, and molding the melt using vacuum and/or compressed air.The blank was integrally laminated on the outer surface. The present invention provides a cup-shaped composite container for retort food.

In carrying out this invention, the simplest structure of the multilayer blank material before offset multicolor printing is to contain an inorganic filler of 8 to 65% by weight, preferably 20 to 55% by weight.
A stretched film of polypropylene containing % by weight is used as a paper-like layer, and the wall thickness is 1-30 microns (μ), preferably 3-30 microns (μ).
10μ polyethylene with density 091-0.97 f/cc, preferably density 0.935-0.9609
/ cc medium-low density or high-density polyethylene as the back layer with a wall thickness of 3 [1 to 300μ].

Preferably, it is a composite sheet having a two-layer laminated structure of 1511-250μ.

Such a composite sheet is produced by melting polypropylene containing an inorganic filler and the polyethylene in separate extruders.
After kneading, the mixture is fed into the same die, laminated in the die and coextruded into a sheet, and after cooling to 4C) ~ 80°C, proceed to 134.
Reheat to 164°C, preferably 145-16 (1°C), and biaxially stretch the film by 35-1 (1 times) in the longitudinal and transverse directions simultaneously or sequentially, if necessary. 1
It is obtained by annealing at 65 to 168°C for 5 to 60 seconds.

The polypropylene film containing an inorganic filler was made using the difference in circumferential speed between the rolls to 134-15.
On the film obtained by longitudinal stretching 35 to 7 times at 5°C,
The polyethylene film was melt-laminated and -[,
50 to 8 (after cooling to 1℃, 134 to 164℃, good 1
Alternatively, it can be obtained by reheating the film to 155° C./164° C., and then stretching it 4 to 10 times in the transverse direction using a tenter. In this method for manufacturing a multilayer sheet as well as in the method for manufacturing a composite sheet having three or more layers to be described later, the annealing treatment is performed as necessary after stretching.

When the composite sheet has three or more layers, it can be manufactured in various ways. For example, polypropylene containing 8 to 65% inorganic fine powder, (B) PoIJ 7" Robylene, (
Each of the polyethylenes with a density of 0 to 0.91 - 0,97 f/cc, preferably 0.935 to 0.97 (l f/cc) is melted and kneaded using separate extruders, and the melt is mixed into one Transferred to a die, laminated in the die so that a film consisting of (2) becomes an intermediate layer, and coextruded the laminated sheet at a temperature lower than the melting point of the polypropylene (a), simultaneously or sequentially biaxially stretched. Manufactured by. It's 1 (
After longitudinally stretching the coextruded sheet of polypropylene (B) and polyethylene (Q), the coextruded sheet of (
It can also be obtained by laminating a sheet of the polypropylene composition (A) on the surface side of the polypropylene sheet (B), and then laterally stretching the sheet. Furthermore, (5
It can also be obtained by melt-laminating a sheet of polypropylene composition () and a sheet of polyethylene (0) and then transversely stretching.

In addition, when coextruding the polyethylene layer and the polypropylene layer, if the polypropylene layer side contains polyethylene in an amount of 5 to 25% by weight, a coextruded sheet with a uniform thickness distribution can be obtained.

Among these multilayer sheets, from the viewpoint of offset printability, it is preferable that the paper-like layer of polypropylene containing 8 to 65% by weight of inorganic fine powder is oriented only in the l-axis direction. By stretching, cracks are generated on the surface with the inorganic fine powder as the nucleus, and the adhesion and drying properties of the printing ink are improved. 2
Axial stretching orientation increases the chances of inorganic fine powder falling off, and deep cracks formed by axial stretching may disappear with further stretching, resulting in poor offset printability in l-axis oriented films. Inferior.

However, the number of layers is preferably three or more layers including a biaxially oriented polypropylene film layer as an intermediate layer. This biaxially oriented polypropylene film can give stiffness to the blank and facilitate paper feeding during sheet offset printing.

The wall thickness of the blank used in this invention is 30 to 300.
µ, preferably 150 to 250 µ, and the thickness of the back layer is 1 to 30 µ, preferably 3 to 2 (l µ). If the thickness of the blank is thinner than 30 µ, paper feeding and offset Printing is difficult. 1. Blank shrinkage may occur during molding. If the thickness exceeds 300 μm, it is economically disadvantageous. The thickness of the polyethylene film on the back layer is determined by vacuum forming.

A thickness of at least 1 μm is required because the polyethylene film is melted by the heat of molten polyethylene during differential pressure molding such as air pressure molding, and the molded product and blank are firmly adhered. Also, 30μ
Exceeding this is not preferable because the blank will curl, making offset printing difficult and making it difficult to fix the blank to the mold.

(In the above blank description, polyethylene is used as an example of a thermoplastic resin having a melting point 15° C. or more lower than that of polypropylene.

Instead of polyethylene, metals (Na, Zn) of ethylene/vinyl acetate copolymer, ethylene/acrylic acid copolymer
, K, etc.) It is also possible to use salts.

The blank is a wall plate partially connected to a bottom plate, and in the present invention, it also includes a sheet-like label. Of course, the composite sheets used to create the blanks can be printed in multiple colors using not only offset printing, but also gravure printing, flexographic printing, and other methods.

Next, the molding sheet) K will be described. This molding sheet is a multilayer structure sheet, and at least the following (a) and (C)
It has three layers.

(a) Polypropylene base layer film (b) Gas barrier resin film (c) Low melting point thermoplastic resin back layer film to be melt-adhered to the label.

In addition, an adhesive film layer is provided, if necessary, for adhesion between these layers or for facilitating heat sealing between the container body and the lid.

The polypropylene base layer film (a) above is used to impart rigidity to the container, and is made of homopropylene polymer (melting point 163-167°C), propylene as the main component (
95 mol% or more), and a copolymer of this with an olefin such as ethylene or butene-1 (melting point 142 to 161°C) is used. If necessary, to improve adhesion with other layers, gas barrier resin, low melting point resin, maleic anhydride kraft polyethylene, maleic anhydride kraft polyethylene, etc. may be added to 0.5% or 20% by weight. There is also. Furthermore, 0.5 to 5% by weight of a pigment such as titanium oxide may be added to give the container an aesthetic appearance. Generally, this polypropylene-based layer film is 40-95% of the wall thickness of the differential pressure molding sheet.
used to occupy the majority of

(b) The resin providing the gas barrier film includes polyamide, such as nylon 6; polyester, fl
, l is polyethylene terephthalate 1 saponified EVA (preferably an ethylene/vinyl acetate copolymer with an ethylene content of 25 to 51 mol%, saponified to a degree of saponification of 93% or more); polyvinylidene chloride can be mentioned. This gas barrier resin film is used so as to account for 1 to 50% of the thickness of the molding sheet.

As the low melting point resin (c), a thermoplastic resin having a melting point 15° C. lower than the melting point of the polypropylene (a) is used. The resin is polyethylene, ethylene,
Metals (Zn, Na, Lj.

K) salts, etc., which need to be compatible with the thermoplastic resin forming the back layer of the label. Polyethylene is preferred from the viewpoint of odorlessness. The thickness of the film (C) accounts for 2 to 2 (1%) of the sheet.

If the adhesion between these layers is poor, use adhesives such as maleic anhydride grafted polyethylene/lene, maleic anhydride kraft polypropylene, maleic anhydride grafted ethylene/vinyl acetate copolymer, or metal salts of ethylene/acrylic acid copolymer. Uses a synthetic resin. For such items, anhydrous
Leic acid-modified polyolefin resins are sold by Mitsubishi Yuka Co., Ltd. under the trade name Modic, and metal salts of the latter copolymer are sold by DuPont under the trade name Surlyn.

As a method for producing a molding sheet with a multilayer structure, +vLj fat forming each layer is melt-kneaded using separate extruders,
Then, the melt is supplied to one die and laminated within the die,
It goes without saying that in addition to the method of manufacturing by coextrusion, it can also be manufactured by an outside-die lamination method or a tandem method.

The wall thickness of this molding sheet is 20,000 microns to 1 micron, preferably 40(l to 1rl).

The present invention will be explained in more detail below based on the accompanying drawings.

The molding of a composite container, that is, a cup-shaped container l, involves forming a wall plate 8 shown in FIG. 1 into a blank 2 to which a bottom plate 9 is partially connected.
2-2 of mold 4 fixed with the back layer facing inside
1 (Guide the molten molding sheet 3 1 cm upward, 1.
With compressed air of 5-7 Kg/ca, or 2-6 (1
This is carried out by differential pressure molding at a reduced pressure of 11 mm Hff or by using both in combination (see Fig. 2). During this molding, the blank 2 comes into contact with the melted thermoplastic resin 3c such as polyethylene, which is the layer (c) of the molding sheet 3, but the paper-like layer 2a side of the blank 2 on which the offset printing 10 is printed is in the mold 4. Since the surface of the paper-like layer 2a is cooled in contact with the paper-like layer 2a, the surface of the paper-like layer 2a does not melt. In other words, multicolor printing does not lose its clarity. Further, since the blank 2 is attached to the cup-shaped container l under pressure and in a state where all of the polypropylene of the paper-like layer 2a of the blank 2 is not melted, shrinkage of the blank 2 is prevented. Note that 2b is a low melting point synthetic resin film and 3a is a polypropylene base layer film. (See Figure 3) The temperature of the molten sheet depends on the gas barrier used (b).
Although it depends on the type of resin 3b, it is generally 14 (1-0°C).

After differential pressure molding, the cup-shaped container is trimmed and collected as a product, and then sent to a filling process.

After filling the container with the contents 7, the lid 5 is heat-sealed to the rim portion 6 of the container 1, and then 110~.1 is heated in the retort pot.
Sterilized at 30℃ for 60 minutes, 20~60℃
A cooled sealed retort food container is obtained by sprinkling with water (see FIG. 4).

According to this method of attaching a blank, the blank can be firmly attached to the molded article without problems such as heat shrinkage or unclear printing, even though the blank uses a stretched film.

Furthermore, since polypropylene, which is highly water and chemical resistant, is used as the blank material, the blank will not peel off due to water sprinkling even if the container obtained by implementing the present invention is used as a retort food container.

The composite container of the present invention obtained by this molding method has the following advantages.

1. It is more economical than tin containers or aluminum retort containers.

2. It is lighter than tin containers and has excellent logistics suitability.

3. Unlike aluminum containers, the container will not dent due to impact.

4. A rigid container whose shape and dimensions can be freely changed can be obtained.

5. Since the container itself can be printed in multiple colors, it is possible to obtain a retort container that is both retortable and fashionable.

Hereinafter, this invention will be explained in more detail with reference to Examples. However, the present invention is not limited to these examples, and any embodiments may be included within the scope of the present invention as long as they do not exceed the gist thereof. Note that parts and percentages in the examples are based on weight.

Example 1゜(B), 87 parts of polypropylene “Mitsubishi Noprene MA-6J (trade name, melting point = 164°C), manufactured by Mitsubishi Yuka Co., Ltd.,
Mitsubishi Yuka Co., Ltd. Weir high-density polyethylene “Yukalon Hard EY-40J (trade name, melting point = 130°C, density 0.95
(1f/cc) After melt-kneading a composition consisting of 10 parts and 3 parts of fired clay using an extruder, it was extruded into a sheet from a die at a temperature of 250°C, and this was continued until the temperature reached about 50°C. The sheet was cooled.

Next, this sheet was heated to about 153[deg.] C., and then stretched 4 times in the machine direction using the difference in circumferential speed between the roll groups to obtain a -axis stretched film.

Separately, (g) polypropylene manufactured by Mitsubishi Yuka Co., Ltd. “Mitsubishi Noblen MA-3J (trade name, melting point 163°C) 57
A mixture of (C) and high-density polyethylene [Yukaronno-de EY-4 (14 (melting point: 134°C)) was melt-kneaded using two separate extruders. , the molten material was heated to 25 (1°C) from two dies.
A three-layer sheet was obtained by extruding polyethylene of (0) into sheets at a temperature of 23°C (1°C) and laminating them on the front and back surfaces of the -axially stretched film.

This three-layer sheet was once cooled to 60°C.

The film was reheated to a temperature of about 163°C until its end of life, stretched 8 times in the transverse force direction using a tenter, then passed through an oven set at 165°C to heat set, and then cooled to about 60°C. By slitting the edges, the thickness of the intermediate biaxially stretched base layer film is 62 microns, the thickness of the obliquely stretched surface layer film made of the composition (a) is 20 microns, and the polyethylene of (C'l) A composite stretched film (1) with a back layer thickness of 8 microns was obtained.

In the above production example, after corona discharge treatment was applied to the paper-like layer side of Tokuda synthetic paper (composite stretched film), Mitsubishi Yuka Co., Ltd.
Acrylic antistatic agent solution ST-13 (1 (+) was applied and dried.

Next, the edges of the composite stretched film are slit, and further,
The composite stretched film was cut into widths of 5 (1 cm) using a knife cutter at right angles to the film flow direction.

The cut composite stretched film was stored in a sheet stocker.

After performing multicolor offset printing according to each purpose on the paper-like layer surface of a sheet-like synthetic paper cut at 1θ1, blanks were obtained by performing a stamping process.

Example 1 (a) Polypropylene [Mitsubishi G-Prene MA-8'j (
Mitsubishi Yuka product name, melting point 164°C) 90 parts, maleic anhydride-modified polypropylene r Modic J l (mixture of 1 part, (b) polyethylene terephthalate r A
RNITE A2 (10J (product name manufactured by AKZO),
(c) High-density polyethylene “Yukalonhar” EY-4
(14 were melt-kneaded in separate extruders, then 1
The melt is supplied to the die on the stand, and inside the die (c) / (a
) / (b) / (a) / (c) were laminated in this order, then coextruded (248°C), and then cooled to a thickness of 8.
(1 (1 micron 5-layer sheet (each wall thickness is 35/3)
I got 50/30/35 (1/35 micron).

Example 2゜(a) Polypropylene MA-895 parts and T:Oz 5
(b) saponified product of ethylene/vinyl acetate copolymer EVALj (trade name manufactured by Kuraray), (c
) Low density polyethylene [Yukalon LK-3 (l j
(trade name manufactured by Mitsubishi Yuka, melting point 119°C') and (d) adhesive resin rModicJ are each melt-kneaded using separate extruders, and then the melt is supplied to one die,
(c) / (d) / (b) / (d) in the die
/ (a) / (d) / (c) were laminated in this order, then coextruded and cooled to obtain a sheet with a 7-layer structure (wall thickness 5 (1/2015 (1/2) (1/69 (1) /2(115
(1 micron).

Go to Example 3・5 (b) As the resin, instead of EVALO, nylon-6[
Tsubamitsudo 1 (14 (trade name) manufactured by Mitsubishi Kasei, or vinylidene chloride-vinyl chloride copolymer “Flex (product name) manufactured by Kureha Chemical Industry Co., Ltd.”), or linear thermoplastic polyester [Vylon 20 (manufactured by Toyobo Co., Ltd.) A sheet having a seven-layer structure with a wall thickness of 9 (10 microns) was obtained in the same manner as in Example 2 above, except that (trade name) was used.

To Example 1/5 The offset-printed blank obtained above was subjected to plate processing to obtain a blank having a bottom plate diameter of 53 mm and a circumferential wall height of 28 m+n.

After fixing 16 of these blanks in the cavity of a vacuum mold so that the printing side was in contact with the cavity surface of the mold, the melted sheets (14
(1 to 1) was introduced 5 cm above the mold using a compressed air vacuum forming machine manufactured by Uniku, and the pressure was reduced (60 mmHf).
) At the same time, compressed air of 9/ca G was supplied from the upper mold side to perform plug assist molding for 10 seconds, and trimming was performed to mold 16 cup-shaped containers at once. The average wall thickness of the container was 55C) to -50 (1 micron).

In either product, there was no fading of the print on the blank, and no deformation of the blank was observed. Furthermore, the adhesion strength between the container body and the blank was strong, and the blank could not be peeled off by hand.

Inside the container printed in multiple colors using the blank obtained in the above example,
The contents (approximately 93° C.) were poured into the container, and then a lid having a four-layer structure of polyethylene terephthalate/Modjc/aluminum foil/polyethylene was heat-sealed to obtain a sealed container.

Place the sealed container obtained in this way in the retort pot +2
(After sterilizing at 1°C for 60 minutes, the container was cooled by sprinkling with water.

No deformation or discoloration was observed in any of the containers. ,
,! ! In addition, no separation between the blank and the container was observed.

[Brief explanation of drawings]

FIG. 1 is a plan view of a blank, FIG. 2 is a sectional view showing the process of forming a composite container of the present invention, and FIG. 3 is a partially cutaway sectional view of a composite container showing an embodiment of the present invention. FIG. 4 is a cross-sectional view of a sealed container filled with contents. In the figure: 1 Composite container (cup-shaped) 2 Blank 2a Paper-like layer 2b Low melting point synthetic resin film 3 Molding sheet 3a Polypropylene base film 3b
Gas barrier and other resins 3c are thermoplastic resins. Patent Applicant Fururashi Shiko Co., Ltd. Patent Applicant Oji Yuka Synthetic Paper Co., Ltd. Procedural Amendment August 3, 1980 Commissioner of the Patent Office Mr. Kazuo Wakasugi1, Indication of the Case 1982 Patent Application No. 1008452, Invention Name Composite container for retort food 3, Relationship with the case of the person making the amendment Patent applicant 4, Agent Address 4th floor, Sakura Masamune Building, 2-1-1 Nihonbashi, Chuo-ku, Tokyo 103 (Contents of amendment 6) Specification Middle School 1) "Terephthalate" on page 4, line 12 is corrected as follows and becomes "terephthalate" 2) "Label" on page 20, line 11 is corrected as follows and "blank" 3) Page 21, line 11 4) Correct “1 label” in the first line of page 23 to “blank” 5) “140 to 160°C” in the second line of page 26 ” was corrected as follows: “140-260°C” 6) On page 28, line 14, [melting point = 130 J was corrected as follows: [melting point = 134 J] 7) “Open” on page 30, line 6 8) Corrected "6.2 microns" in line 8 of the same page as follows and changed it to "62 microns." 9) Corrected "plate processing" in line 10 of page 31 as follows. 10) In line 13 of the same page, ``Mitsubishi Geepren'' was corrected as follows, ``Mitsubishi Nopren.'' 11) In line 9, page 33, ``(Product Motomata)'' was corrected as follows. "(Product name)" +2) On the 13th line of the same page, correct "(Product name)" as follows and change it to "(Product name)" 13) 1-stroke slope on the 3rd line of page 34 14) In line 5 of the same page, correct ``of the die of the mold'' as follows and read ``of the lower die of the die'' +5) Line 8 of the same page "140-160℃" is corrected as follows [140-2600CJ "Figure 2" and "Figure 4" in the attached drawings are corrected as shown in the attached sheet.

Claims (1)

[Claims] 1. The blank is integrally formed in a container, obtained by molding a heated thermoplastic synthetic resin composite sheet using compressed air and/or vacuum on the inner surface of a blank inserted into a mold. In a papermaking container having a thermally bonded structure, the blank has a paper-like layer made of a stretched polypropylene film containing 8-65% by weight of inorganic fine powder, and the surface opposite to this paper-like layer (the back surface). 1 from the melting point of the constituent polypropylene
Wall thickness of thermoplastic resin with melting point lower than 5℃ 1-3
The thermoplastic synthetic resin composite sheet is composed of (a) a polypropylene base film, and (b) polyamide, polyester, ethylene/acetic acid. (c) a resin film layer with low gas permeability selected from saponified vinyl copolymers and polyvinylidene chloride;
It has a melting point that is 15°C or more lower than the polypropylene, and. The composite sheet for molding has at least a back layer made of a thermoplastic resin film that is compatible with the thermoplastic resin constituting the back layer of the blank, and the bonding is between the back layer of the blank and the back surface of the composite sheet for molding. A composite container for retort food with a structure in which layers are thermally bonded. 2. The composite container for retort food according to claim 1, wherein the paper-like layer side of the blank is printed in multiple colors. 3. Claims characterized in that the blank has a structure including a paper-like layer made of a uniaxially stretched film and a base layer made of a biaxially stretched polypropylene film between the paper-like layer and the back layer. The composite container for retort food according to item 1 or 2. 4. Claim 1, wherein the thermoplastic resin constituting the back layer of the blank is polyethylene.
The composite container for retort food according to item 2, item 2, or item 3. 5. For retort food according to claim 1, 2, 3, or 4, wherein the thermoplastic resin constituting the back layer of the composite sheet for molding is polyethylene. Composite container.