JP2007238155A - Packaging body for air containing boiling - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent whitening due to precipitation on the film surface of a low molecular weight component containing in a bi-axially oriented polyamide film of a constitution material of the package bag wherein a package bag can withstand an air-containing boiling treatment, a boil puncture ratio of a bag-breakage ratio due to boil puncture in the air-containing boiling treatment is low, and which is generated by the air-containing boiling treatment, and suppress moisture permeability of the package bag in the air-containing treatment in the air-containing boiling packaging body wherein the air-containing treatment is performed by hermetically sealing a water-containing food to the package bag in an air-containing state. <P>SOLUTION: In the air-containing boiling package body which is composed by at least polypropylene-based un-oriented film and the bi-axially oriented polyamide film, and wherein the air-containing treatment is performed by hermetically sealing the water-containing food to the package bag, the boil puncture ratio measured under a specified condition is not larger than 15%, and the whitening due to precipitation on the film surface of the low molecular weight component containing in the bi-axially oriented polyamide film is not generated on the package bag surface after evaluation of the boil puncture ratio. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a package for an air-containing boil, and more specifically, at least a polypropylene-based unstretched film and a biaxially stretched polyamide film are used as constituent materials, and a moisture-containing food is sealed in a package bag in an air-filled state. When the aerated boil package subjected to the boil treatment (hereinafter also referred to as the aerated boil treatment) is subjected to the aerated boil treatment, the packaging bag of the package can withstand the aerated boil treatment. The low molecular weight component contained in the biaxially stretched polyamide film, which is a constituent material of a packaging bag generated by the aeration boil treatment, with a low boil puncture rate in the aeration boil treatment, that is, a bag breakage rate due to the boil puncture The present invention relates to a package for an aerated boil that does not cause whitening due to precipitation on the film surface.

In recent years, with the improvement of food culture, authenticity has become stronger, and noodle instant foods are also being switched from dry noodle types to raw noodle types. In the case of the raw noodle type, heat sterilization is performed after the raw noodles are sealed and packaged in an aerated state. Since this heat sterilization process is performed in an aerated state, a large stress is applied to the seal portion due to expansion of air and water vapor inside the sealed body due to heat. For this reason, only the sealing strength of the conventional packaging material is insufficient in terms of characteristics, and sealability and pressure resistance that can withstand the internal pressure generated by the air-containing boil treatment are required. In recent years, the aerated boil conditions have become more severe in order to meet high taste demands. As a laminated film for an air-containing boil packaging body that can withstand this requirement, a laminated film composed of a polypropylene-based unstretched unstretched film and a biaxially stretched polyamide film is disclosed (for example, see Patent Document 1).
JP-A-9-239929

  The laminated film for an air-containing boil package disclosed in the above patent document satisfies the market demand for suppressing the boil puncture rate in the air-containing boil treatment, but the biaxially stretched polyamide by the air-containing boil treatment There is a problem that a low molecular weight component composed of a polyamide monomer, an oligomer, or the like contained in the film is deposited on the film surface, and the surface whitening phenomenon of the laminated film may occur. Since the whitening phenomenon gives consumers a sense of filth by generating mold and food contamination, it has been strongly desired to improve it.

  In addition, with the recent increase in consumer-oriented luxury, there is an increasing demand for more severe management of the moisture content of packaged water-containing foods, and market demands for reducing the moisture permeability of packaging bags are increasing. .

  In the laminated film for an air-containing boiled package, the property of the polypropylene-based unstretched film, which is a constituent material of the laminated film, greatly affects the suppression of the boil puncture rate in the air-borne boil treatment, which is an important characteristic. The improvement is being promoted.

For example, in response to these requirements, a polypropylene system comprising a blend of an ethylene random copolymer polypropylene polymer and a binary copolymer of ethylene and propylene or butene-1 or a terpolymer of these and a non-conjugated diene. It has been proposed to improve low-temperature heat sealability with an unstretched film (see, for example, Patent Document 2).
JP-A-5-262900

  However, the above method is not compatible with a binary copolymer of ethylene random copolymer and ethylene and butene or a ternary copolymer of these and a non-conjugated diene. Voids are formed, the sealing strength is reduced, and the internal pressure generated by the air-containing boil treatment cannot be withstood.

It has also been proposed to improve low-temperature heat sealability by using a propylene / α-olefin copolymer having a specific melting peak temperature, melting start temperature, and melting end temperature for the heat-sealing layer, that is, the sealing layer. (For example, see Patent Document 3).
JP 2004-268532 A

  However, although the method disclosed in Patent Document 3 improves the low-temperature heat sealability, it uses ethylene / α-olefin for the laminate layer, and the interlaminar strength decreases at the time of boiling, which makes it easy to peel off. There was a problem that the laminate layer was whitened.

Furthermore, by laminating a base layer made of an ethylene random copolymer polypropylene polymer with a seal layer containing an ethylene random copolymer polypropylene polymer and a polyolefin random copolymer elastomer, low-temperature sealability and aerated boil puncture resistance are achieved. Improvement has been proposed (see, for example, Patent Document 4).
Japanese Patent Laid-Open No. 10-166526

  However, the above method is excellent in the resistance to aerated boil puncture when a biaxially stretched polyamide film that is easily deformed is used as the base film, but the case where a large amount of an organic slip agent is added for high speed processing or When a material that is not easily deformed at the time of boiling, such as a biaxially stretched polyester film or a biaxially stretched polypropylene film, is used as the material film, there is a problem that the aeration boil puncture resistance is impaired.

  An object of the present invention is to solve the above problems, and more specifically, in an aerated boil package in which an aerated boil treatment is performed by sealing a hydrated food in a packaging bag in an aerated state. The packaging bag can withstand the aeration boil treatment, the boil puncture rate, which is the boil puncture rate due to the boil puncture in the aeration boil treatment, is low and the constituent material of the packaging bag generated by the aeration boil treatment A laminated film for an air-containing boil package and an air-boiled boil packaging in which whitening due to precipitation of a low molecular weight component contained in the biaxially stretched polyamide film is not generated and the moisture permeability of the packaging bag is further suppressed To provide a body.

As a result of intensive studies to solve the above problems, the present inventors have completed the present invention.
That is, the present invention is an aerated boiled package comprising a laminated film comprising at least a polypropylene-based unstretched film and a biaxially stretched polyamide film as a constituent material, wherein a moisture-containing food is sealed in an aerated state and subjected to a boil treatment. The boil puncture rate measured under the following conditions is 15% or less, and whitening occurs due to the migration of low molecular weight components contained in the biaxially stretched polyamide film to the surface of the package after the evaluation of the boil puncture rate It is an aerated boiled package characterized by not having.
Evaluation method of boil puncture rate The laminated film for an air-containing boiled package is formed into a three-side sealed bag having an inner size of 13 cm × 13 cm and an outer size of 14 cm × 14 cm. The sealing conditions for bag making are as follows: pressure 0.2 MPa, time 1 second, and temperature 200 ° C. The three-side sealed bag is filled with 200 cc of water and 200 cc of air, and sealed under the same sealing conditions as above. The 100 sealed bags are boiled for 60 minutes, the number of bags broken during the boil processing is counted, and the boil puncture rate is obtained by the following equation.
Boil puncture rate (%) = (number of bags broken / 100) × 100

In this case, it is preferable that the moisture permeability of the laminated film for an air-containing boil packaging is 2.0 g / m ² · 24 h or less.

  In this case, the sealing strength of the laminated film for an air-containing boil packaging body is preferably 53 N / 15 mm or more.

  In this case, the laminated film for an air-containing boil package may be formed by laminating a polypropylene-based unstretched film, a biaxially stretched polyamide film, a biaxially stretched polypropylene film, and / or a biaxially stretched polyester film in the above order. preferable.

  In this case, the polypropylene-based unstretched composite film preferably has a seal strength of 13.0 N / 15 mm or more.

  In this case, the polypropylene-based unstretched film is composed of at least two layers of a laminate layer and a seal layer, and (1) the laminate layer is propylene / α- having an α-olefin content of 2 to 8% by mass. Olefin Random Copolymer Resin (A) 40-70% by mass and α-olefin content 3-10% by weight propylene / α-olefin block copolymer resin (B) and / or xylene soluble at 20 ° C. The propylene / ethylene block copolymer resin (C) having a part of 5 to 12% by mass, a melting point of 130 to 150 ° C., and an ethylene content of 6 to 15% by mass, (2) The seal layer has 80 to 90% by mass of propylene / α-olefin random copolymer resin (A) having an α-olefin content of 2 to 8% by mass and 20 ° C. It consists of 10 to 20% by mass of propylene / ethylene block copolymer resin (C) having a soluble part of 5 to 12% by mass, a melting point of 130 to 150 ° C., and an ethylene content of 6 to 15% by mass. Is preferred.

  In this case, an intermediate layer is laminated between the laminate layer and the seal layer, and the intermediate layer is a propylene / α-olefin random copolymer having an α-olefin content of 2 to 8% by mass. The propylene / α-olefin block copolymer resin (B) having a resin (A) of 60 to 85% by mass and an α-olefin content of 3 to 10% by weight and / or 5 xylene-soluble parts at 23 ° C. It consists of 15 to 40% by mass of an ethylene / propylene block copolymer resin (C) having a melting point of 130 to 150 ° C. and an ethylene content of 6 to 15% by mass, and a laminate layer and an intermediate layer It is preferable to increase the amount of the propylene / α-olefin random copolymer resin (A) contained in the seal layer in the order of laminate layer <intermediate layer <seal layer.

In this case, the biaxially stretched polyamide film is preferably subjected to a water-resistant easy adhesion treatment. In addition, it is preferable to use a biaxially stretched polypropylene film or a biaxially stretched polyester film that does not have antistatic properties.
In this case, the polypropylene-based unstretched film, biaxially stretched polyamide film, biaxially stretched polypropylene film, and biaxially stretched polyester film have thicknesses of 20 to 65 μm, 12 to 28 μm, 17 to 33, and 12 to 25 μm, respectively. It is preferable that

  In addition, the present invention is a package for aerated boil, wherein a moisture-containing food is enclosed in a packaging bag made of the above laminated film for aerated boiled package.

  The package for an aerated boil using the laminated film for an aerated boil package of the present invention is such that when the hydrated food is sealed in an aerated state and subjected to an aerated boil treatment, the package can withstand the aerated boil treatment. The boil puncture rate in the aerated boil treatment is low, and the low molecular weight component contained in the biaxially stretched polyamide film which is a constituent material of the package generated by the aerated boil treatment is transferred to the package surface and deposited. Therefore, the laminated film for an aerated boil packaging body of the present invention is used as a packaging material for an aerated boil packaging body in which the aerated food is sealed in an aerated state and subjected to an aerated boil treatment. It can be used suitably. That is, the low boil puncture rate in the aerated boil treatment can improve the reliability of the aerated boiled package. Moreover, since the occurrence of whitening makes consumers feel unclean by image of the occurrence of mold and food contamination, the problem can be avoided by suppressing the occurrence of whitening. In addition, the package for aerated boil using the laminated film for aerated boiled package according to the present invention has moisture permeability suppressed, so that the moisture content of the packaged moisture-containing food can be treated with aerated boil. It is possible to suppress the change caused by, so that it is possible to answer the high demands of consumers' taste.

The laminated film for an air-containing boil package according to the present invention comprises at least a polypropylene-based unstretched film and a biaxially stretched polyamide film as constituent materials, and an air-containing boil in which a moisture-containing food is sealed in an air-containing state and subjected to a boil treatment. In a laminated film for an aerated boil packaging body used as a packaging material for a packaging body, the boil puncture rate measured under the following conditions is 15% or less, and the biaxial to the surface of the packaging body after evaluation of the boil puncture rate It is important that whitening (hereinafter sometimes referred to as whitening phenomenon) due to migration of low molecular weight components contained in the stretched polyamide film does not occur.
[Evaluation method for boil puncture rate]
The laminated film for an air-containing boil package is formed into a three-side sealed bag having an inner size of 13 cm × 13 cm and an outer size of 14 cm × 14 cm. The sealing conditions for bag making are as follows: pressure 0.2 MPa, time 1 second, and temperature 200 ° C. The three-side sealed bag is filled with 200 cc of water and 200 cc of air, and sealed under the same sealing conditions as above. The 100 sealed bags are boiled for 60 minutes, the number of bags broken during the boil processing is counted, and the boil puncture rate is obtained by the following equation.
Boil puncture rate (%) = (number of bags broken / 100) × 100

  The boil puncture rate evaluated by the above method is more preferably 10% or less, and further preferably 5% or less. In the case of exceeding 15%, in the air-containing boil treatment of the packaged body in which the moisture-containing food is packaged, the steam generated by the evaporation of water contained in the food and air inside the sealed body expands due to heat. A large stress is applied to this, and there is a high probability that bag breakage will be caused by the destruction of the seal portion due to the pressure, and the reliability as a package is lowered.

  Among the above requirements, those other than the requirement that the whitening phenomenon does not occur are known as described above. Therefore, the novelty of the present invention is to add the characteristic that the whitening phenomenon does not occur while satisfying the conventionally known configuration and characteristics.

Moreover, it is preferable that the moisture permeability of the laminated film for an air-containing boil packaging body of the present invention is 5.5 g / m ² · 24 h or less. The moisture permeability is more preferably 4.0 g / m ² · 24 h or less,
3.0 g / m ² · 24 h or less is more preferable.

When the moisture permeability exceeds 5.5 g / m ² · 24 h, the moisture content change in the moisture-containing food packaged by the above-described aerated boil treatment and the time before and after the treatment increases, for example, consumers It is not preferable because it becomes impossible to respond to the high demands of the taste of the past.

  The present invention provides a laminated film for an aerated boil packaging body that satisfies the conventionally known configuration and characteristics and maintains the reliability as an aerated boil packaging body, and increases the commercial value as a packaging body by adding the above characteristics, and The object is to provide an aerated boiled package. The method for adding the above characteristics is not limited. For example, it is preferable to form a coating or a layer that can add the above properties on the surface of a biaxially stretched polyamide film of a laminate comprising a conventionally known polypropylene-based unstretched film and a biaxially stretched polyamide film. As the coating, a method of coating a coating having a barrier property such as an oxide coating made of an inorganic oxide composed of vinylidene chloride, silica, alumina, and a composite component thereof, or a hybrid coating of the oxide and an organic substance. Is mentioned.

  As a method of forming the layer, it is preferable to laminate a biaxially stretched polypropylene film, a biaxially stretched polyester film, or the like.

  Of the above methods, the method of coating a vinylidene chloride coating is not preferable in terms of environmental load. In addition, the method of coating the oxide-based coating has a problem in terms of reliability such as durability of the coating due to deformation of the packaging bag in the air-containing boil treatment. Therefore, the method of laminating the latter layer is a more preferred embodiment. In the case of carrying out by this method, the content is not limited as long as the above characteristics can be added after satisfying the conventional characteristics, but the polypropylene-based unstretched film, biaxially stretched polyamide film, biaxially stretched polypropylene film and / or biaxial It is a preferred embodiment that the stretched polyester film is laminated in the above order. In this case, the polypropylene-based unstretched unstretched film, biaxially stretched polyamide film, biaxially stretched polypropylene film and biaxially stretched polyester film have thicknesses of 20 to 65 μm, 12 to 28 μm, 17 to 33 and 12 respectively. It is preferably ˜25 μm.

  Further, the biaxially stretched polyamide film is preferably subjected to a water-resistant easy adhesion treatment. For example, use of Harden (trademark registered) film, N6062, 15 μm, etc. manufactured by Toyobo Co., Ltd. is preferable. By this measure, the reliability of the effect of suppressing the aerated boil puncture rate is improved.

  In addition, it is preferable to use a biaxially stretched polypropylene film or a biaxially stretched polyester film that does not have antistatic properties. As the biaxially stretched polypropylene film, for example, Pyrene (trademark registered) film manufactured by Toyobo Co., Ltd., P2102, 20 μm and the like are preferable. The biaxially stretched polyester film is preferably, for example, Toyobo Ester (trademark registered) film manufactured by Toyobo Co., Ltd., E5100, 12 μm or the like. By the correspondence, the above-described additional effect of the present invention can be exhibited.

Since the elongation stress in the wet heat state is increased by the above configuration, the stress when the laminated film is stretched 75% in hot water at 90 ° C. exceeds 2.8 × 10 ⁷ Pa. Because the puncture rate increases, countermeasures are necessary.

The present inventors have found that the above problem can be solved by setting the sealing strength of the laminated film to 53 N / 15 mm or more. 55N / 15mm or more is more preferable, 57
N / 15 mm or more is more preferable. When the sealing strength of the laminated film is less than 53 N / 15 mm, the boil puncture rate is increased, which is not preferable.

  The method for satisfying the sealing strength of the laminated film is not limited, but the sealing strength of the polypropylene-based unstretched film is preferably 13.0 N / 15 mm or more. The seal strength is more preferably 13.5 N / 15 mm or more, and further preferably 14.0 N / 15 mm or more. A sealing strength of less than 13.0 N / 15 mm is not preferable because the sealing strength of the laminated film is lowered and the boil puncture rate is increased.

  Although the method of satisfying the sealing strength of the polypropylene-based unstretched film is not limited, the polypropylene-based unstretched film is composed of at least two layers of a laminate layer and a seal layer. (1) The laminate layer has an α-olefin content. 2-8 mass% propylene / α-olefin random copolymer resin (A) 40-70 mass% and α-olefin content 3-10 wt% propylene / α-olefin block copolymer resin (B ) And / or propylene / ethylene block copolymer resin (C) having a xylene-soluble portion of 5 to 12% by mass at 20 ° C., a melting point of 130 to 150 ° C., and an ethylene content of 6 to 15% by mass. Propylene / α-olefin comprising 30 to 60% by mass, (2) the sealing layer having an α-olefin content of 2 to 8% by mass Propylene having an ethylene content of 80 to 92% by mass, a xylene-soluble part at 20 ° C. of 5 to 12% by mass, a melting point of 130 to 150 ° C., and an ethylene content of 6 to 15% by mass. -It is preferable to use what consists of 8-20 mass% of ethylene block copolymer resin (C).

  Also, an intermediate layer is laminated between the laminate layer and the seal layer, and the core layer has a propylene / α-olefin random copolymer resin (A) having an α-olefin content of 2 to 8% by mass. Of the propylene / α-olefin block copolymer resin (B) having an α-olefin content of 3 to 10% by weight and / or 5 to 12% by weight of a xylene soluble part at 23 ° C. And 15 to 40% by mass of an ethylene / propylene block copolymer resin (C) having a melting point of 130 to 150 ° C. and an ethylene content of 6 to 15% by mass, and in the laminate layer, intermediate layer and seal layer It is preferable to use a product in which the amount of the propylene / α-olefin random copolymer resin (A) contained in is increased in the order of laminate layer <intermediate layer <seal layer.

The polypropylene unstretched film will be described below.
First, three types of resins that are important elements in the above configuration will be described.
Resin (A)
The resin (A) according to the present invention is a propylene / α-olefin random copolymer resin having an α-olefin content of 2 to 8% by mass. The content of α-olefin is more preferably 3 to 7% by mass, and further preferably 4 to 6% by mass. When the α-olefin content is less than 2% by mass, the low-temperature sealing property is inferior, and when it exceeds 8% by mass, the blocking resistance deteriorates. Examples of the α-olefin include ethylene, 1-butene, 1-hexene, 4-methyl / 1-pentene, 1-octene and the like. In these, the random copolymer with ethylene and / or 1-butene is preferable. The MFR is not particularly limited as long as it can be a film, but it is usually in the range of 0.5 to 20 g / 10 minutes, preferably 2 to 10 g / 10 minutes. Further, the propylene / α-olefin copolymer (A) according to the present invention usually has a molecular weight distribution (expressed by a ratio of the weight average molecular weight Mw and the number average molecular weight Mn) in the range of 1.5 to 3. It is preferable. When it exceeds 3, low molecular weight substances increase and blocking resistance deteriorates. Therefore, it is preferable to polymerize using a single site catalyst.

Resin (B)
The resin (B) according to the present invention is a propylene / α-olefin block copolymer resin having an α-olefin content of preferably 2 to 10% by mass, more preferably 4 to 8% by mass. When the α-olefin content is less than 2% by mass, the impact resistance is inferior, and when it exceeds 8% by mass, the transparency and rigidity are deteriorated. Examples of the α-olefin include ethylene, 1-butene, 1-hexene, 4-methyl / 1-pentene, 1-octene and the like. In these, ethylene and / or 1-butene are preferable. The MFR is not particularly limited as long as it can be a film, but is usually in the range of 0.5 to 10 g / 10 minutes, preferably 1 to 5 g / 10 minutes. When the MFR is less than 0.5 g / 10 min, the productivity is inferior, and when it exceeds 10 g / 10 min, the impact resistance is inferior.

Resin (C)
The resin (C) according to the present invention is a propylene / ethylene block copolymer resin having an ethylene content in the range of 6 to 15% by mass. The resin (C) preferably has a xylene-soluble portion ratio at 20 ° C. of 5 to 12% by mass and a melting point of 130 to 150 ° C.
As for ethylene content, 7-14 mass% is more preferable, and 8-13 mass% is further more preferable. If the ethylene content is less than 6% by mass, the flexibility is poor, which is not preferable. On the other hand, if it exceeds 15% by mass, the rigidity decreases, which is not preferable.
The ratio of the xylene soluble part is more preferably 6 to 11% by mass, and further preferably 7 to 10% by mass. If the ratio of the xylene-soluble part is less than 6% by mass, the impact resistance is inferior, which is not preferable. On the contrary, when it exceeds 12 mass%, since transparency will deteriorate, it is not preferable.
As for the said melting | fusing point, 135-145 degreeC is more preferable. When the melting point is less than 130 ° C., the blocking resistance is deteriorated. Conversely, when the melting point is 150 ° C. or more, the low-temperature sealing property is deteriorated.

  In the present invention, the blending ratio of the resin (A), the resin (B) and the resin (C) in the laminate layer is such that the resin (A) is 40 to 70% by mass and the remaining 60 to 30% by mass is the resin ( B) and / or resin (C) are preferred. The ratio of the resin (A) is more preferably 45 to 65% by mass. When the proportion of the resin (A) is less than 40% by weight, the transparency is deteriorated. Conversely, if it exceeds 70% by weight, the resistance to aerated boil puncture is deteriorated.

In the present invention, the resin (A), the resin (B), and the resin (C) are mixed in the intermediate layer in a proportion of 60 to 85% by mass of the resin (A), and the remaining 40 to 15% by mass of the resin (A). B) and / or resin (C) are preferred. The ratio of the resin (A) is more preferably 55 to 80% by mass.
When the ratio of the resin (A) is less than 60% by mass, the transparency is deteriorated. On the contrary, when it exceeds 85 mass%, aeration boil puncture tolerance will deteriorate.

  In the present invention, the resin composition in the seal layer is preferably a combination of two types of resin (A) and resin (C). If the sealing layer is blended with the resin (B) blended in the laminate layer or intermediate layer, the low-temperature sealing property is lowered, which is not preferable. The blending ratio of the resin (A) and the resin (C) is preferably 80 to 92% by mass of the resin (A). 82-90 mass% is more preferable. When the ratio of the resin (A) is less than 80% by mass, the blocking resistance is deteriorated. On the contrary, when it exceeds 92 mass%, the low-temperature sealing property deteriorates.

  The above-mentioned resin (A), resin (B) and resin (C) according to the present invention are generally used as antioxidants, weathering stabilizers, antistatic agents, antifogging agents, as long as the object of the present invention is not impaired. Additives such as antiblocking agents, lubricants, nucleating agents, pigments or other polymers can be blended as necessary. In particular, the sealing layer contains various known anti-blocking agents such as inorganic compound particles such as silica, talc, zeolite and aluminum borate, and organic compound particles such as polymethyl methacrylate, melamine formalin resin, melamine urea resin and polyester resin. Addition of 0.01 to 1% by mass is preferable because a film having further improved anti-blocking properties can be obtained. Among these, silica and polymethyl methacrylate are particularly preferable in terms of antiblocking properties and transparency.

  In the seal layer and the intermediate layer, various known slip agents such as hydrocarbon, fatty acid, higher alcohol, aliphatic amide, metal soap, ester, etc. are added in an amount of 0.01 to 0.5. Addition by mass% is preferable because a film with improved slip properties can be obtained. Among these, when a combination system of erucic acid amide with immediate effect and delayed-acting behenic acid amide is used, stability of winding of the film at the time of film formation by subsequent erucic acid amide and subsequent cutting processing, printing The laminate workability can be improved, while the slow-acting behenic acid amide that is hardly adsorbed by the adhesive can improve the slipperiness and anti-blocking properties after dry lamete.

  Further, in the sealing layer, high density polyethylene, dibenzylidene sorbitol, methyl substituted dibenzylidene sorbitol, hydroxy-di-aluminum, bissorbicyl, bis-sodium methylene bis-acid phosphate sodium Addition of 0.01 to 1.0% by weight of various known crystallization nucleating agents such as salt suppresses the generation of roll marks during film formation, and provides slip and blocking properties immediately after film formation. Is preferable because an improved film can be obtained. Among these, the use of a polyethylene crystallization nucleating agent that is relatively easy to add and has no problem with odor can improve the quality and processability immediately after the film forming process in a well-balanced manner.

  It is preferable to add 0.01 to 1% by mass of various known anti-blocking agents to the laminate layer because a film with improved anti-blocking property of the film product roll can be obtained.

  In addition, as a method for adding these additives and polymers, a method of directly feeding into an extruder at the time of film formation is possible, but a master batch using a polymer used in the present invention as a base resin is prepared in advance. A method of feeding this master batch into an extruder during film formation is preferred.

  The manufacturing method of said resin (A) concerning this invention, resin (B), and resin (C) is not limited. It can be produced by various known methods, for example, using a Ti-based Ziegler catalyst whose main component is Ti, Mg, Cl or the like. However, as described above, the propylene / α-olefin random copolymer resin (A) is particularly preferably a resin produced using a single site catalyst. The single site catalyst is a catalyst having a uniform active site (single site), and examples thereof include a metallocene catalyst (so-called Kaminsky catalyst) and a Brookhart catalyst. For example, a metallocene catalyst is a catalyst composed of a metallocene transition metal compound, an organoaluminum compound and at least one compound selected from the group consisting of compounds that react with the metallocene transition metal compound to form an ion pair. It may be carried on.

In a propylene / α-olefin random copolymer resin, it is common to increase the content of α-olefin in order to lower the sealing start temperature. However, when the content of α-olefin is increased, the film becomes soft and the blocking resistance is deteriorated.
On the other hand, the molecular weight distribution of the resin (expressed by the ratio of the mass average molecular weight Mw to the number average molecular weight Mn) increases the molecular weight distribution as the value increases, so the low molecular weight product increases and the blocking resistance deteriorates. To do. Therefore, in order to balance low-temperature heat sealability and blocking resistance, it is effective to narrow the molecular weight distribution of the resin and reduce low molecular weight products. In order to narrow this molecular weight distribution, it is effective to perform polymerization using a single site catalyst having uniform activity.

  The thickness of the propylene-based unstretched film is preferably 20 to 65 μm. 30-55 micrometers is more preferable. Moreover, as for the thickness ratio of each layer, in the case of a two-layer type, it is desirable that the ratio of the sealing layer is 50 to 80% and the ratio of the lamellar layer is 20 to 50%. Furthermore, it is more desirable that the ratio of the sealing layer is 55 to 70% and the ratio of the lamellar layer is 30 to 55%. When the ratio of the sealing layer is less than 50%, the transparency is deteriorated, and when it exceeds 70%, the aerated boil puncture resistance is deteriorated.

  In addition, the thickness ratio of each layer in the case of the three-layer type is desirably 5 to 40% for the seal layer, 30 to 80% for the intermediate layer, and 10 to 30% for the laminar layer. Further, the ratio of the seal layer is more preferably 10 to 35%, the ratio of the intermediate layer is 40 to 75%, and the ratio of the lami layer is more preferably 15 to 25%.

  If the thickness ratio of the seal layer is less than 10%, the low-temperature sealability is deteriorated, which is not preferable. Conversely, if it exceeds 40%, blocking resistance and film rigidity are lowered, which is not preferable.

  If the thickness ratio of the intermediate layer is less than 30%, the rigidity of the film decreases, which is not preferable. On the other hand, if it exceeds 80%, the resistance to aerated boil puncture is lowered, which is not preferable.

  When the thickness ratio of the laminate layer is less than 10%, the resistance to aerated boil puncture is lowered. Conversely, if it exceeds 30%, the transparency deteriorates, which is not preferable.

  The propylene-based unstretched film can employ various known film forming methods such as an inflation method and a T-die method. In addition, such films may be laminated separately after film formation, but the method of film formation by coextrusion using a multilayer die having a three-layer structure is most preferable. Examples of the method for co-extrusion film formation include lamination using a feed block and a method using a multi-manifold die.

  In order to improve the adhesion to other films, the above-mentioned propylene-based unstretched film is subjected to oxidation treatment by corona treatment, flame treatment, plasma treatment, etc., or surface activity by undercoat treatment, etc. It is also possible to carry out the conversion process.

In this invention, it is preferable that the adhesive agent used for the said laminate consists of a polyester urethane type, and the application quantity is 1.5-3.5 g / m < ² >. The coating amount of the adhesive layer is more preferably 2.0 to 3.0 g / m ^2. If an adhesive made of polyether urethane is used, or if the adhesive layer thickness does not satisfy the above range, the boil puncture rate is deteriorated. Moreover, when the adhesive layer thickness is thick, it is not preferable from the viewpoint of economy.

Although the laminating method of the said structure is not limited, For example, it is preferable to laminate on the following conditions.
Polyester urethane adhesive (main agent: aromatic having a secondary transition point (Tg) of −16 ° C. on a biaxially stretched polypropylene film, a biaxially stretched polyester film, or a laminate of a biaxially stretched polypropylene film and a biaxially stretched polyester film) An aliphatic copolymerized polyester polyol and a crosslinking agent: hexamethylene diisocyanate trimer) were applied so that the solid content concentration of the adhesive was 2.5 g / m ^2, and the temperature was 2 to 5 at a temperature of 60 to 120 ° C. After pre-drying for 2 seconds, a biaxially stretched polyamide film is laminated between a metal roll and a rubber roll that have been temperature-controlled at 50 to 80 ° C. On the biaxially stretched polyamide film side of the laminate produced by the above method, a polyester urethane-based adhesive (main agent: aromatic / aliphatic copolymer polyester polyol having a secondary transition point (Tg) of −16 ° C., cross-linking agent: hexagon. Methylene diisocyanate trimer) is applied so that the solid content concentration of the adhesive is 2.5 g / m ^2, and preliminarily dried at a temperature of 60 to 120 ° C. for 2 to 5 seconds, and then 50 to 80 ° C. A propylene-based unstretched film is laminated between a metal roll and a rubber roll that have been temperature-controlled.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited by the following examples, but may be implemented with appropriate modifications within a scope that can meet the gist of the present invention. These are all included in the technical scope of the present invention.

  The measurement and evaluation methods employed in the present specification are as follows.

1. Melt flow rate [MFR]
(2004 edition) Measured according to JIS K7210 by the method of Condition-14 (load 2.16 kg, temperature 230 ° C.).

2. Melting point About 6 mg of propylene-based copolymer (C) was weighed, and increased to 200 ° C. at a rate of temperature increase of 10 ° C./min using a differential scanning calorimeter (type 5200) manufactured by Seiko Denshi Kogyo Co., Ltd. Warming and holding at 200 ° C. for 5 minutes, then cooling rate: cooling rate to 0 ° C. at 100 ° C./min, temperature rising rate; melting curve when the temperature is raised from 0 ° C. to 200 ° C. at 10 ° C./min From this melting curve, the method of (2004 version) JIS-K-7121 9.1 was followed, and the temperature at the top of the melting peak on the highest temperature side was melted from the melting curve.

3. Ratio of xylene soluble part at 20 ° C (%)
After 5 g of the sample was completely melted in 500 ml of boiling xylene, the temperature was lowered to 20 ° C. and left for 4 hours or more. Thereafter, the precipitate and the solution were separated by filtration, and the filtrate was dried and dried at 70 ° C. under reduced pressure. From the mass of the obtained dried product, the 20 ° C. xylene-soluble part amount was measured, and the ratio was determined.

4. Ethylene content Measured by ¹³ C-NMR method according to the method described on page 616 of Polymer Handbook (published by Kinokuniya Shoten in 1995).

5. Haze (2004 version) Measured according to JIS-K-6714 using “Haze Tester J” manufactured by Toyo Seiki Seisakusho.

6. Blocking resistance In accordance with ATM-D1893-67, apply a load of 90N to the area of A4 size, leave the load for 2 hours in an atmosphere of 60 ° C, remove the load, and then remove the peeling resistance with a φ5 aluminum rod at a moving speed of 100 mm / min. It measured on condition of this.

7. Seal temperature Place the sample so that the seal faces face each other, and place a biaxially stretched polyester film (“Toyobo Ester” film [E5100 12 μm] made by Toyobo Co., Ltd.) on both sides and use a thermal gradient type 5-point sealer Then, sealing was performed at a pressure of 0.2 MPa for 1 second, and the sealing strength was measured at a width of 15 mm. Create a graph where the seal temperature is 5 points on a 5 ° C pitch of 120 ° C to 140 ° C and the temperature is on the horizontal axis and the seal strength is on the vertical axis. The temperature at which the seal strength reaches 4.9 N / 15 mm (500 g / 15 mm) It was read on the graph and this temperature was defined as the seal temperature.

8. Seal strength Polypropylene-based unstretched composite film or laminated film is heat-sealed at a pressure of 0.2 MPa, a time of 1 second, and a temperature of 200 ° C., and T-type peeled off with a tensile tester at a tensile speed of 100 mm / min. The seal strength in the MD direction was determined.

9. Tensile elastic modulus (2004 version) According to JIS K7127, the sample shape conforms to the No. 1 type test piece (sample length 200 mm, sample width 15 mm, chuck distance 100 mm), and crosshead speed 500 mm / min. It measured about MD direction (film longitudinal direction) on conditions. Unit MPa.

10. Evaluation method of boil puncture rate A laminated film for an air-containing boil package was formed into a three-side sealed bag having an inner dimension of 13 cm × 13 cm and an outer dimension of 14 cm × 14 cm with the polypropylene-based unstretched film as the inner surface side. The sealing conditions for bag making were a pressure of 0.2 MPa, a time of 1 second, and a temperature of 200 ° C. The three-side sealed bag is filled with 200 cc of water and 200 cc of air, and sealed under the same sealing conditions as above. The 100 sealed bags were boiled for 60 minutes, the number of bags broken during the boil treatment was counted, and the boil puncture rate was determined by the following formula.
Boil puncture rate (%) = (number of bags broken / 100) × 100

11. Whitening phenomenon in air-containing boil treatment The surface of the sealed body evaluated by the above method was observed with the naked eye, and judged according to the following criteria.
○: Whitening is not observed
X: Whitening is observed

12. Moisture permeability A laminated film sample for an air-containing boiled package was measured using a water vapor permeability measuring device (PARMATRAN-W, manufactured by Modern Controls) under the conditions of 40 ° C. and 90% RH.

13, Measurement of thickness of film, seal layer, and laminate layer A cross section of the film was cut out and measured by reflected light using an optical microscope.

Resins used in the preparation of propylene-based unstretched films of Examples and Comparative Examples are as follows.
Resin (A): Propylene / ethylene random copolymer polymerized with metallocene catalyst (ethylene content = 4 mass%, MFR = 7)
Resin (B): Propylene / ethylene block copolymer (ethylene content = 6 mass%, MFR = 2.5)
Resin (C): Propylene-based copolymer (ethylene content = 10 mass%, 20 ° C. xylene soluble part 10%, melting point 140 ° C., MFR = 3))

Example 1
[Preparation of propylene-based unstretched film]
As a laminate layer, a composition comprising 60% by mass of resin (A), 20% by mass of resin (B), 20% by mass of resin (C), 600 ppm of amorphous silica (Silycia 550) having an average particle diameter of 3 μm, and 400 ppm of erucamide. The product is used as a sealing layer in the form of 88% by mass of resin (A), 12% by mass of resin (C), 2000 ppm of amorphous silica having an average particle size of 3 μm (Silysia 550), 1000 ppm of spherical silica having an average particle size of 4 μm, and erucamide. A composition composed of 600 ppm and 200 ppm behenic acid amide was melt-extruded using separate extruders, and T-die casting was performed under conditions of a T-die outlet resin temperature of 250 ° C., a speed of 50 m / min, and a cooling roll temperature of 30 ° C. A polypropylene-based unstretched composite film having a laminate layer thickness of 15 μm and a seal layer thickness of 25 μm was obtained. . The properties of the obtained film are shown in Table 1.
The average particle size of the inorganic particles was measured using a laser diffraction particle size distribution measuring device (Nikkiso Microtrack HRA model 9320-X100) manufactured by Lees & Northrup, and displayed as a volume average particle size.

[Preparation of laminated film for aerated boiled packaging]
Biaxially stretched polyamide film (Toyobo "Harden (registered trademark)" film N6062 15 μm) and non-static type biaxially stretched polypropylene film (Toyobo "Pyrene (registered trademark)" film P2102 20 μm ) And a polyester urethane adhesive (main agent: aromatic / aliphatic copolymer polyester polyol having a secondary transition point (Tg) of −16 ° C., cross-linking agent: hexamethylene diisocyanate trimer). It was applied so that the partial concentration was 2.5 g / m ^2, and dry laminated according to a conventional method to obtain a two-layer laminate. Furthermore, on the biaxially stretched polyamide film side of the laminate obtained by laminating, a polyester urethane-based adhesive (main agent: aromatic / aliphatic copolymer polyester polyol having a secondary transition point (Tg) of −16 ° C., crosslinking agent: Hexamethylene diisocyanate trimer) was applied so that the solid content concentration of the adhesive was 2.5 g / m ^2, and a polypropylene-based unstretched film was dry-laminated according to a conventional method.
Table 3 shows the characteristic values of the obtained laminated film for an air-containing boil packaging.
The laminated film for an aerated boil package obtained in this example has high sealing strength, and the aerated boil package obtained by molding the laminated film has a low aerated boil puncture rate and is laminated by an aerated boil treatment. The whitening phenomenon of the film was not observed. Further, the moisture permeability was low, and it was high quality as an air-containing boil package.

(Example 2)
Example 1 except that the biaxially stretched polyester film (“Toyobo Ester (trademark)” film E5100, 12 μm, manufactured by Toyobo) is used instead of the biaxially stretched polypropylene film in the method of Example 1. In the same manner, a laminated film of Example 2 was obtained. Table 2 shows the characteristic values of the obtained laminated film. The laminated film obtained in this example has slightly lower moisture permeability than the laminated film obtained in Example 1, but has the same characteristics as the laminated film obtained in Example 1, and is molded. The package for air-containing boil thus obtained was of high quality.

(Comparative Example 1)
In the method of Example 1, a laminated film of Comparative Example 1 was obtained in the same manner as in Example 1 except that the lamination of the biaxially stretched polypropylene film was stopped. Table 2 shows the characteristic values of the obtained laminated film.
In the laminated film obtained in this comparative example, the whitening phenomenon due to the migration of the low molecular weight component contained in the biaxially stretched polyamide film to the surface of the polyamide film occurred in the air-containing boil treatment. Moreover, the packaging bag for an air-containing boil package obtained by processing this with high moisture permeability was of low quality.

(Comparative Example 2)
A laminated film of Comparative Example 2 was obtained in the same manner as in Example 1 except that the resin composition used in each layer of the polypropylene-based unstretched film used in the method of Example 1 was changed as shown in Table 1. The characteristic values of the obtained laminated film are shown in Table 3.
Since the polypropylene-based unstretched film used in these comparative examples had low sealing strength, the laminated film obtained from the polypropylene-based unstretched film had low sealing strength. Therefore, the package for an aerated boil obtained by processing this has a high aerated boil puncture rate and a low quality.

(Example 3)
In the method of Example 1, the polypropylene-based unstretched film and laminate of Example 3 were prepared in the same manner as in Example 1, except that the polypropylene-based unstretched film was changed to the three-layer type prepared by the following method. A film was obtained. The characteristic values of the obtained polypropylene-based unstretched film and laminated film are shown in Tables 2 and 3, respectively. The laminated film obtained in this example has the same properties as the laminated film obtained in Example 1 and is of high quality, and the inclusion of the package for an air-containing boil obtained by processing this film. The air boil puncture rate was also low. .
[Preparation of propylene-based unstretched film]
As a laminate layer, a composition comprising 60% by mass of resin (A), 20% by mass of resin (B), 20% by mass of resin (C), 600 ppm of amorphous silica (Silycia 550) having an average particle diameter of 3 μm, and 400 ppm of erucamide. A composition comprising, as an intermediate layer, 70% by mass of resin [A] having an ethylene content of 4% by mass, 5% by mass of resin (B), 25% by mass of resin (C), and 300 ppm of erucamide, As a sealing layer, resin (A) 88% by mass, resin (C) 12% by mass, amorphous silica (Silycia 550) having an average particle diameter of 3 μm, 2000 ppm, spherical silica having an average particle diameter of 4 μm, 1000 ppm, erucic acid amide 600 ppm, behenine A composition comprising 200 ppm of acid amide was melt extruded using a separate extruder, and the T-die outlet resin temperature was 250 ° C. 50 m / min, and T-die cast under the conditions of a cooling roll temperature 30 ° C., to obtain laminate layer thickness 10 [mu] m, an intermediate layer thickness of 20 [mu] m, the polypropylene-based non-stretched composite film of the sealing layer thickness of 10 [mu] m. The properties of the obtained film are shown in Table 2.
The average particle size of the inorganic particles was measured by the same method as in Example 1.
In addition, the above-mentioned amorphous silica, spherical silica, erucic acid amide, and behenic acid amide are each prepared as a master batch previously added to the resin (A) at a high concentration, and the additive concentration becomes a predetermined value during melt extrusion. The masterbatch was added as follows.

(Comparative Examples 3 and 4)
Laminated films of Comparative Examples 3 and 4 were obtained in the same manner as in Example 3 except that the resin composition used in each layer of the polypropylene-based unstretched film used in the method of Example 3 was changed as shown in Table 2. The characteristic values of the obtained laminated film are shown in Table 3.
Since the polypropylene-based unstretched film used in these comparative examples has a low sealing strength like the polypropylene-based unstretched film obtained in Comparative Example 2, the laminated film obtained from the polypropylene-based unstretched film has a sealing strength. Was low. Therefore, the package for aerated boil obtained by processing this has a high aerated boil puncture rate and a low quality.

  The package for an aerated boil of the present invention is such that when an aerated boil package in which a water-containing food is sealed in a package bag in an aerated state, the package bag of the package can withstand the aerated boil treatment. The low boil puncture rate in the aerated boil treatment is low, and the low molecular weight component contained in the biaxially stretched polyamide film, which is a constituent material of the packaging bag generated by the aerated boil treatment, is deposited on the film surface. Since the occurrence of whitening is suppressed, it can be suitably used as an aerated boiled package in which a hydrated food is sealed in a packaging bag in an aerated state and subjected to an aerated boil treatment. That is, the low boil puncture rate in the aerated boil treatment can improve the reliability of the aerated boiled package. Moreover, since the occurrence of whitening makes consumers feel unclean by image of the occurrence of mold and food contamination, the problem can be avoided by suppressing the occurrence of whitening. In addition, since the air-permeable boil packaging body of the present invention has suppressed moisture permeability, the moisture content in the packaged water-containing food can be suppressed because it can suppress changes in the air-containing boil treatment and time. It can answer the high demands of the taste of the person. Therefore, the package of the present invention can be suitably used as a device for an aerated boil. Therefore, it is important to contribute to the industry.

Claims (11)

Boil puncture rate measured under the following conditions in an aerated boil package in which at least a polypropylene-based unstretched film and a biaxially stretched polyamide film are used as constituent materials, and a moisture-containing food is sealed in an aerated state and boiled. An aerated boiled package characterized in that whitening does not occur due to migration of a low molecular weight component contained in a biaxially stretched polyamide film to the surface of the packaged body after evaluation of the boil puncture rate .
Evaluation method of boil puncture rate The laminated film for an air-containing boiled package is formed into a three-side sealed bag having an inner size of 13 cm × 13 cm and an outer size of 14 cm × 14 cm. The sealing conditions for bag making are as follows: pressure 0.2 MPa, time 1 second, and temperature 200 ° C. The three-side sealed bag is filled with 200 cc of water and 200 cc of air, and sealed under the same sealing conditions as above. The 100 sealed bags are boiled for 60 minutes, the number of bags broken during the boil processing is counted, and the boil puncture rate is obtained by the following equation.
Boil puncture rate (%) = (number of bags broken / 100) × 100 2. The aerated boiled package according to claim 1, wherein a moisture permeability of a laminated film constituting the aerated boiled package is 5.5 g / m ² · 24 h or less.   The aerated boiled package according to claim 1 or 2, wherein the sealing strength of the laminated film is 53 N / 15 mm or more.   The laminated film is formed by laminating a polypropylene-based unstretched film, a biaxially stretched polyamide film, a biaxially stretched polypropylene film and / or a biaxially stretched polyester film in the above order. The aerated boiled package as described.   5. The aerated boiled package according to claim 1, wherein the polypropylene-based unstretched composite film has a seal strength of 13.0 N / 15 mm or more.   The polypropylene-based unstretched film comprises at least two layers of a laminate layer and a seal layer, and (1) a laminate layer is a propylene / α-olefin random copolymer resin (α-olefin content is 2 to 8% by mass) A) Propylene / α-olefin block copolymer resin (B) having 40 to 70 mass% and α-olefin content of 3 to 10 wt% and / or 5 to 12 mass of xylene-soluble part at 20 ° C. %, The melting point is 130 to 150 ° C., and the ethylene content is 6 to 15% by mass, and the propylene / ethylene block copolymer resin (C) is 30 to 60% by mass, and (2) the sealing layer is α- 80 to 90% by mass of propylene / α-olefin random copolymer resin (A) having an olefin content of 2 to 8% by mass and 5 to 12 xylene-soluble parts at 20 ° C. The propylene / ethylene block copolymer resin (C) having a melting point of 130 to 150 ° C. and an ethylene content of 6 to 15% by mass is 10 to 20% by mass. An air-containing boiled package according to any one of the above.   An intermediate layer is laminated between the laminate layer and the seal layer, and the intermediate layer is composed of 60 propylene / α-olefin random copolymer resin (A) having an α-olefin content of 2 to 8% by mass. The propylene / α-olefin block copolymer resin (B) having a content of ˜85% by mass and an α-olefin content of 3 to 10% by weight and / or a xylene soluble part at 23 ° C. of 5 to 12% by mass, It consists of 15 to 40% by mass of an ethylene / propylene block copolymer resin (C) having a melting point of 130 to 150 ° C. and an ethylene content of 6 to 15% by mass, and is contained in the laminate layer, intermediate layer and seal layer The amount of the propylene / α-olefin random copolymer resin (A) to be increased is increased in the order of laminate layer <intermediate layer <seal layer.   The aerated boiled package according to any one of claims 1 to 7, wherein the biaxially stretched polyamide film is formed by a water-resistant easy adhesion treatment.   The aerated boiled package according to any one of claims 1 to 8, wherein the biaxially stretched polypropylene film and the biaxially stretched polyester film have antistatic properties.   The polypropylene-based unstretched unstretched film, biaxially stretched polyamide film, biaxially stretched polypropylene film, and biaxially stretched polyester film have thicknesses of 20 to 65 μm, 12 to 28 μm, 17 to 33, and 12 to 25 μm, respectively. The aerated boiled package according to any one of claims 1 to 9.   The aerated boil package according to claim 1, wherein a moisture-containing food is enclosed.