JPS6024014B2 - Food packaging for high temperature heat sterilization - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a food packaging bag for high temperature heat sterilization, and more specifically, during high temperature heat sterilization (so-called retort sterilization),
The present invention relates to a heat-sealed food packaging bag in which a very small amount of components contained in the layers constituting the food packaging bag migrate into the food contents, and a method for manufacturing the same.

Conventional food packaging bags for high temperature heat sterilization usually consist of an outer layer made of a heat-resistant resin such as polyethylene terephthalate or polycarbonate, an inner layer made of a heat-sealable polyolefin film such as polyethylene or polypropylene, and often aluminum foil. It was constructed by heat-sealing the periphery of two laminated films laminated together with an intermediate layer bonded with an isocyanate adhesive or the like.

That is, the green peripheral part of the film constituting the inner layer in contact with the food of the packaging bag was used as it is as the heat-sealable resin.

In this case, the inner surface of the bag is entirely covered with a heat-sealable polyolefin film, such as polyethylene or polypropylene film. Relatively low molecular weight components such as plasticizers, antioxidants, catalyst residues, low molecular weight polyolefins and blended rubbers contained in the food, especially oil-containing foods, migrate into the food content (see Table 1), resulting in flavor, There is a problem that taste, color tone, etc. may be impaired, and it is also undesirable from a sanitary point of view. The above problems should be solved if the inner layer of the bag is made of a synthetic resin that is less likely to be extracted by the food contents during high-temperature heat sterilization treatment, instead of using polyolefin resin, etc., as the inner layer of the bag. All of these layers have poor heat-sealability and cannot be easily and reliably heat-sealed to seal the periphery of the bag like conventionally used polyolefin resin films. In this case, it is necessary to apply some kind of adhesive to seal the periphery. Conventionally, there has been a technique called part coating as a method of applying adhesive to such a surrounding green area.

This liquid adhesive is applied using rollers to form a continuous pattern of constant medium (inside the adhesive) lines in a grid pattern with the same shape and dimensions as the periphery of the bag on the surface of the synthetic resin film that is the material of the bag. This method involves applying the agent and drying it. However, since the adhesives conventionally used in this method are solvent-based such as polyvinylidene chloride, they do not withstand high-temperature heat sterilization, and can easily cause bubbles and peel when treated at 120°C for 30 minutes. This caused the bag to lose its sealing performance as a food packaging bag.

An object of the present invention is to provide a food packaging bag for high-temperature heat sterilization in which the amount of bag material components transferred into the food contents is extremely small during high-temperature heat sterilization treatment.

The next object of the present invention is to make heat sealing, that is, heat rutting, easy and reliable, and to prevent damage not only during high-temperature heat sterilization treatment but also due to drop impact during storage, transportation, handling, etc. To provide a food packaging bag for high-temperature heat sterilization having a hard and strong heat-sealed green part. According to the present invention, there is provided a food packaging bag in which the edges of opposing rectangular bag films are heat-sealed with a heat-sealable resin layer, and the inner layer of the bag film in contact with food is , the following formula [1} Emi 0.1% by weight
...'1l In the formula, E is formed of polyethylene terephthalate that satisfies the extraction amount of low molecular weight components when boiled in n-hepta for 30 minutes, and the heat-sealable resin layer is
A food packaging bag for high-temperature heat sterilization characterized by being formed into a square shape or a square shape and made of polyester ether resin consisting of units satisfying the following formula (2'), where R is It is an aromatic divalent group, R2 and R3 are each an alkylene group, p is a number of 2 or more, and m, n, and g are numbers of 1 or more.

The present invention will be explained in detail below.

The food packaging bag of the present invention differs from conventional food packaging bags for high-temperature heat sterilization in which the green part of the inner layer film in contact with the food content functions as a heat-sealable resin. One feature is that the bag is sealed using a heat-sealable resin having a specific composition and having a square or U-shape.

To explain this using an example, FIG. 2 is a plan view of a first example of the packaging bag of the present invention, in which the green portions on the four sides of the bag made of flexible material 1 are transparent inside. It is heat-sealed with a heat-sealable resin film piece 2 (FIG. 1) having a rectangular shape (the outer periphery is not limited to a square but also includes a rectangle) having holes, and is further heat-sealed in a cross-sectional view as shown in FIG. 3. As shown, the inner layer la in contact with the food contents is the heat-sealable resin film piece 2.
It is made of a specific synthetic resin that has a very low extractability of low molecular weight components.

FIG. 6 shows a second embodiment of the present invention,
The three local edges of the bag are heat-sealed with U-shaped heat-sealable film pieces 3 (FIG. 4).

FIG. 9 shows a third embodiment of the present invention,
The bottom of the bag, the green end of the filling opening, and the lap seam are heat-sealed with a U-shaped heat-sealable film piece 3.

The flexible material 1 (hereinafter referred to as bag film) constituting the food packaging bag of the present invention is preferably made of a laminated film including a metal foil and a synthetic resin layer, and the inner layer constituting at least the surface in contact with food is as follows. It is important to have a synthetic resin layer that satisfies the formula and has a very small extraction amount in order to achieve the object of the present invention.

Emi 0.1% by weight...'1' Here, E is the amount of low molecular weight components extracted when boiling in n-hepta for 3 minutes.

N-hebutane was selected as the diluting agent because it is suitable for foods to be stored in the food packaging bag of the present invention, such as curry, stew, meat sauce, cream stew, soup, or meat or processed fish products. This is because numerous experiments have confirmed that there is a high correlation between the amount of components contained in the bag material extracted by oil-containing foods and the amount extracted by boiling in n-hebutane.

If the extraction amount E under the above conditions exceeds 0.1% by weight,
There is a risk that the flavor, taste, and color of the contents of the food will be impaired.Furthermore, as food hygiene standards tend to become stricter year by year, there is a risk of hygienic problems, so the upper limit of the extraction amount E has been set at 0.1% by weight. And so.

The extraction amount E is measured as follows. A sample of a certain weight of the synthetic resin film that constitutes the inner layer la of a food packaging bag that is in contact with the food is cut into small pieces, soaked in a certain amount of n-hebutane, and boiled for 30 minutes (the boiling point of n-hebutane is Satoshi.4
qo) After removing the sample piece, the n-hebutane is removed by evaporation, the residual solution is weighed, and the weight % amount is determined from the comparison with the weight of the original sample. Inner layer la that satisfies the above conditions
As a material constituting the film, polyethylene terephthalate has an extremely low extraction amount E of low molecular weight components as shown in Table 1, is low cost, and has good mechanical strength (especially in the case of stretched films). It is particularly suitable because of its advantages such as:

In addition, as long as the extraction amount of the above formula is satisfied, various additives such as pigments, antioxidants, and thickeners may be added to the inner layer. When packaged food is to be stored at room temperature for a long period of time, perfect gas barrier properties are often required, depending on the type of food contained. ) is desirable. In this case, the bag film 1 preferably has a structure of inner layer la+metal foil+heat-resistant resin coating (outer layer).

The above-mentioned outer layer has functions such as anti-corrosion coating and damage prevention of the metal foil, and is, for example, a film made of polyester resin, polycarbonate resin, polypolyolefin resin, etc., or a baked coating film such as ferrepoxy resin. It's normal. Furthermore, if a food packaging bag is required to have high impact resistance against dropping, etc., polyamide resin, polycarbonate resin, polyester resin, or polyether may be used between the inner layer la and the metal foil and/or between the outer layer and the metal foil layer. A suitable impact-reducing layer made of resin or the like can be provided. Each of these layers is adhered with an isocyanate adhesive or the like. The thickness of each of the above layers is determined to be an appropriate value in consideration of the functions to be shared by each layer, ie, gas barrier properties, strength, etc., within a range that maintains the flexibility of the bag film as a whole. To give an example of a preferable thickness, the inner layer la made of polyethylene terephthalate constituting the surface in contact with food is 5
~100mm, metal foil 7~50mm,
It is not necessarily limited to these. The thermosealable resin used in the present invention has excellent heat fusion properties with the inner layer la constituting the surface that comes into contact with food and, if necessary, the outer layer, and is not altered by high-temperature heat sterilization treatment. It is required that there be no reduction in adhesive strength, no peeling of the adhesive layer, no formation of pores, etc.

Here, the high temperature heat sterilization treatment refers to treatment by steam heating or electronic heating at a temperature of 100 qo to 160 qo for several tens of seconds to several tens of minutes.

As a synthetic resin that satisfies these requirements, the following formula [
A polyester-ether resin composed of units satisfying 2} is suitable.

In the formula, R is an aromatic divalent group, R2 and R3 are each an alkylene group, P is a number of 2 or more, and m, n
and g is a number of 1 or more.

This resin has the disadvantage that polyethylene terephthalate resin has an extremely narrow heat-sealable temperature range, is difficult to heat-seal at commercial speeds, and generally has weak peel strength, whereas polyether resin has poor heat resistance and water resistance. By selecting the combination of the above-mentioned structural units, it is possible to obtain a material with excellent heat-sealability and hot water resistance. Among them, R is a phenylene group,
As R2 and R3, linear alkylene groups having 2 to 6 carbon atoms give preferable results. The thickness of the heat-sealable resin film pieces 2 and 3 is preferably 30 to 100 mm.

If it is thinner than 30mm, a satisfactory adhesive effect cannot be obtained;
Even if it exceeds 00 Am, no particular improvement in adhesion is observed.
This is because, on the contrary, defects such as protruding burrs may occur.

Next, a method for manufacturing a food packaging bag according to the present invention will be explained.
A. As shown in Fig. 1, the outer circumferential dimension matches that of the food bag to be heat-sealed, and the interior is transparent or has an inner diameter that is equal or approximately equal to that of the target adhesive (usually sides 7 to 15). A bag film 1 whose inner layer is made of polyethylene terephthalate satisfying the formula It is heat-sealed on top of the inner layer la so that the edge green portions match.

These two sheets are stacked one on top of the other, and the three sides are heat-sealed and sealed, leaving a twilled end portion for food filling. After filling the food, the remaining one is further heat-sealed. In this case, one of the bag films may be used without heat-sealing the heat-sealable film pieces 2 as they are. Alternatively, the bag film 1 to which the square-shaped film 2 is heat-sealed may be folded in half along its center line, stacked on top of each other, and then heat-sealed. Heat fusion and heat sealing are performed by any known means such as a heated roll method, infrared heating, high frequency heating, and ultrasonic method. FIG. 2 is a plan view of the packaging bag formed as described above, and FIG. 3 is a sectional view taken along line A--A in FIG. 2. When using a U-shaped heat-sealable film piece 3 (hereinafter referred to as a U-shaped film piece), place one half of the bag film 1 cut to twice the intended size as shown in Figure 5. After dispensing the U-shaped film piece 3 so that the green edges of each end coincide with each other, the bag film 1 is folded and overlapped along the line connecting the left ends of the U-shape, and then heat-sealing is performed. Then, a packaging bag as shown in FIG. 6 is formed. FIG. 7 shows a sectional view taken along line B--B in FIG. 6. In addition, as shown in FIG. 8, a U-shaped film piece 3 whose upper and lower parallel parts are approximately twice as long as the length of the target packaging bag is heated to a bag body film cut to a predetermined size. 9, the vertical part of the U-shaped film piece 3 is folded in half to form a lap seam part so that the vertical part of the film piece 3 overlaps with the opposite side of the bag film, and then the lap seam part is folded. It is also possible to form a packaging bag by heat-sealing the bottom edge and heat-sealing the top edge after filling with the food contents.

FIG. 10 shows a cross-sectional view along line A--A in FIG. In this embodiment, the outer layer of the bag film 1 is also made of polyethylene terephthalate. C. Next, the continuous manufacturing method of food packaging bags of the present invention will be explained.

First, as shown in FIG. 11, a heat sealable film web 4 is prepared.
A large number of through holes 5 arranged continuously are provided by press punching or the like.

The dimensions of the through holes are made equal to the inner dimensions of the heat-sealed section of the target packaging bag, and the distance between the through-holes is preferably twice that of the inside of the heat-sealed section. However, there is no harm in making it larger than twice. 1st
FIG. 2 shows a heat-sealing layer, in which the web 4 provided with numerous through holes as described above passes through the belt 6.
The upper surface of the web 7 of the bag film (inner layer la of the food packaging bag)
(corresponding to the surface), and then thermally fused by a thermal adhesion roll 8. As the heat fusing roll, a Teflon roll with a built-in heater or the like is preferably used.

Next, the webs 9 that have passed through the mature fusing roll 8 are laminated so that the heat-sealed portions exactly match each other, or the webs 9
After laminating the web of film and bag film, heat sealing bar (high frequency coil or Teflon bar with built-in electric heater, etc.)
By heat-sealing the bag, leaving the edge that will become the filling opening of the packaging bag, and then cutting the bag, it is possible to continuously and efficiently manufacture the packaging bag. As described above, when producing the heat-sealable resin film pieces 2 and 3 having a square shape or a U shape, a problem arises in that a large amount of scrap is generated.

As a means for this, when punching out the above-mentioned square or U-shaped film pieces one by one, a square film piece for a smaller packaging bag is punched out from the resulting square film piece. There is a way. Even in this case, the generated scrap can be remelted and then recycled into a film by a known method such as a T-die or an inflation method. In the case of recycling, it is usually necessary to add some new resin to prevent deterioration, but polyester-polyether resin has minimal thermal deterioration, so there is almost no need to add new resin. Economically superior. Compared to other heat-sealable resins such as polyamide resins, polyester-polyether resins have less flavor transfer (from the end surface of the resin in the heat-sealed part) to the food contents during high-temperature heat sterilization treatment, and are more susceptible to drop impact. The heat-sealed portion is characterized by high resistance to A heat-sealable resin layer having a square shape or a U shape can also be formed from powder of the resin using an electrostatic method such as electrostatic coating or electrostatic printing.

In this case, there is an advantage that no scrap loss occurs. In the case of the electrostatic coating method, masking is performed in a predetermined shape and arrangement on the grounded bag film itself or on a non-adhesive sheet substrate such as Teflon, and then heat-sealable resin is applied using a known method. Charged fine particles are deposited on a substrate under high DC voltage to a predetermined thickness in a rectangular or U-shape, and then the particles are fused together using a hot roll or other means.

In the case of a bag film, it is possible to simultaneously fuse the particles together and thermally adhere them to the film using a hot roll. When using a non-adhesive sheet, heat-seal a rectangular or U-shaped heat-sealable resin film piece, in which particles adhere to each other to form a film, to the bag film in the same manner as described above. do. Instead of masking, a small electrostatic powder gun that applies the electric field curtain principle that can discharge a stream of charged particles with a small diameter (for example, "Metal Materials Nikkan Kogyo Shinbunsha, November 1973, 39-45") By moving the nozzle of the electrostatic powder gun (described on page) into a square or U-shape, or by forming the nozzle of an electrostatic powder gun into a square or U-shape, and discharging the charged fine particles from there, Heat-sealable resin particles may be attached to the substrate in a square or U-shape.In the case of electrostatic printing, a square- or U-shaped charged portion is formed on the surface of the substrate, and then thermosealable resin particles are attached on the substrate. After depositing the fine particles to a predetermined thickness, a rectangular or U-shaped heat-sealing resin layer is heat-sealed onto the bag film by the same means as described above.

After the above-mentioned package is filled with the food contents, it is degassed, the filling opening is heat-sealed, and then the package is subjected to high-temperature heat sterilization treatment.

Suitable food contents include cooked or semi-cooked foods that can be eaten as is or heated prior to consumption.

An example is as follows. Cooked curry, cooked hash, borscht, various stews such as beef stew, various gravies such as meat sauce, various vegetables such as sweet and sour pork, sukiyaki, Chinese bean paste, Happo greens, boiled asparagus, boiled IJumu etc. , stewed seafood and/or preserved products, boiled hollyhock and boiled products: Various soups such as consommé and potage, miso soup, pork soup, kenchin soup, and other soups: boiled rice, sekihan,
Rice such as kamameshi, cooked rice, pilaf, porridge, etc.; Dumplings such as spaghetti, soba, udon, ramen, noodles, etc.; Food supplements such as kamameshi mix, Chinese soba mix, boiled azuki beans, zenzashi, and anmitsu. Favorite foods such as meatballs, hamburgers, beefsteaks, roast pork, sautéed pork,
Corned beef, ham, sausage, grilled fish, yakiniku, yakitori, roasted chicken, pork ketchup, fish meat, bacon, kamaboko, and other processed meat or fish products.

In the food packaging bag of the present invention, the surface that comes into contact with food is formed of an inner layer made of polyethylene terephthalate, which has an extremely small amount of extraction, so that almost no low molecular weight components migrate into the food contents during high-temperature heat sterilization. It is extremely hygienic.

In addition, the sealing part of the bag is firmly thermally bonded with a heat-sealing resin film made of polyester ether resin with a specific structure, so it can be used not only during high-temperature heating under harsh conditions, but also during transportation or storage. Peeling or deterioration of the sealing portion can also be sufficiently prevented.

The above effects will be more apparent from the following examples. [Example 1] A 12 rm thick biaxially oriented polyethylene terephthalate film, a 9 m thick aluminum foil, and a 12 rm biaxially oriented polyethylene terephthalate film were laminated and bonded in this order using an isocyanate adhesive, and the three layers were bonded together. A bag film was obtained, which was cut into a predetermined rectangular size.

In addition, a 50 rm thick polyester-ether film (Toyobo Belprene) with a melting point of 200 qo was punched out in the center IW rib to obtain a heat-sealable rectangular film piece whose peripheral dimensions were equal to those of the bag film. . As shown in Figure 2, a piece of white multi-layered film on one side of the bag film is heat-sealed at 290q0 using a heat roll, and two laminates are made by laminating a heat-sealable film on the 4th circumferential twill. Created. These two laminated materials were placed facing each other so that the heat-sealable film portions were aligned, and three sides were thermocompression bonded at 290° C. for 3 seconds at a pressure of 3k9/base to obtain a food packaging bag. This seal strength is 2.0
It was K9/2 Enbutachu. After filling this packaging bag with curry, the filling opening is heat-sealed under the same conditions as above, and then
Retort sterilization was performed for 120 qo x 30 minutes, but there were no abnormalities such as peeling of the heat-sealed portion or generation of bubbles, and the seal strength after retort sterilization was 1.8 kg/20 mm width. Furthermore, the flavor and color tone of the food contents were also good. Table 1 a Boiling the inner layer material with n-hebutane for 30 minutes and the amount of extract expressed as a percentage of the weight of the tested inner layer material.

b Enclose 200 g of n-hebutane in the bag of each example (13 m x 17 m), seal and heat at 65°C for 2 hours, and calculate the amount of extract by weight of test n-hebutane. divided value.

c A normal retort/guchi using a high-density polyethylene film with a melting point of 120°C on the entire inner layer. d Melting point 14
A regular retort pouch that uses 0tsu0 cast polypropylene film on the entire inner layer.

[BRIEF DESCRIPTION OF THE DRAWINGS] Fig. 1 is a plan view of a heat-sealable film piece formed in a square shape, and Fig. 2 is a plan view of the heat-sealable film piece of the present invention formed using the heat-sealable film piece of Fig. 1. 3 is a plan view of a food packaging bag according to the first embodiment, FIG. 3 is a longitudinal cross-sectional view taken along line A-A in FIG. 2, and FIG. A plan view, FIG. 5 is a plan view of the heat-sealable film piece shown in FIG. 4, heat-sealed to a bag film, and FIG. 6 is a plan view of the heat-sealable film piece shown in FIG. 4 formed using the heat-sealable film. A plan view of a food packaging bag according to a second embodiment of the present invention, FIG. 7 is a sectional view taken along line B-B in FIG. 6, and FIG. FIG. 9 is a plan view of a piece of heat-sealable film formed, a third embodiment of the invention having a lap seam formed using the heat-sealable film of FIG. A plan view of a food packaging bag, FIG. 10 is a sectional view taken along the line C-C in FIG. 9, FIG. 11 is a plan view of a web of heat-sealable film in which continuous holes are formed, and FIG. 12 FIG. 1 is a perspective view showing an example of an apparatus for continuously manufacturing food packaging bags of the present invention. 1... Bag film, la... Inner layer in contact with food, 2, 3.
・・Heat-sealable I resin film piece (heat-sealable resin layer), 4
... Heat-sealable resin film web, 5... Through holes,
7... Bag film web, 8... Heat sealing roll. Figure 1 Figure 2 Figure 3 Dance diagram Figure 5 Figure 6 Blind Figure 7 Figure 8 Blind Figure 9 Figure 10 Calculation Figure 11 Figure J312 Figure

Claims (1)

[Claims] 1. A food packaging in which the edges of opposing rectangular bag films are heat-sealed with a heat-sealing resin layer, and the inner layer of the bag film in contact with the food is as follows: Formula (1) E≦0
．． 1% by weight...(1) In the formula, E is formed of polyethylene terephthalate that satisfies the extraction amount of low molecular weight components when boiled in n-heptane for 30 minutes, and the heat sealable resin layer is , a food packaging bag for high-temperature heat sterilization characterized by being made of a polyester-ether resin formed in a square or square shape and consisting of units satisfying the following formula (2);
▲There are mathematical formulas, chemical formulas, tables, etc.▼ In the formula, R_1 is an aromatic divalent group, R_2, R
Each of _3 is an alkylene group, p is a number of 2 or more, and m, n, and g are a number of 1 or more. 2. The food packaging bag for high-temperature heat sterilization according to claim 1, wherein the heat-sealable resin layer is formed by an electrostatic method.