JP5314528B2 - Packaging materials and methods of use - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new, unique and excellently versatile packaging material or the like capable of storing not only an object to be packaged with a little water content but also the object to be packaged containing a large amount of water content and a liquid component, for a long period at a high quality, and capable of suppressing an excessive deterioration of quality of a package, the object to be packaged in the package and the packaging material even when temperature and humidity in the package are changed. <P>SOLUTION: The packaging material is formed by molding a resin composition containing a thermoplastic resin, and includes at least one moisture transmission controlling layer having a transition region where an increase in water vapor transmission amount W<SB>VTR</SB>from a reference temperature T<SB>S</SB>(&deg;C) to a temperature T<SB>S</SB>+10(&deg;C) of 2-100 times of an increase in water vapor transmission amount W<SB>VTR</SB>from T<SB>S</SB>-10(&deg;C) to the reference temperature T<SB>S</SB>(&deg;C), in a plot-chart of temperature (&deg;C)-water vapor transmission amount W<SB>VTR</SB>(g/(m<SP>2</SP>h)) measured under a moisture condition of 60%RH based on JIS L1099 A-2 method, and having a reference temperature T<SB>S</SB>(&deg;C) in the range of 0-100&deg;C. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a packaging material whose water vapor transmission amount changes dramatically depending on temperature, and a method of using the same.

  Conventionally, packaging materials such as resin films and resin molded bodies have been widely used. In general, this type of packaging material is required to have the ability to block the package from the outside, that is, high sealing performance, thereby preventing the moisture and liquid components from oozing out of the package, and packaging of dust and foreign matters. Prevention of intrusion into the inside and prevention of infection due to invasion of pathogens such as bacteria and bacteria in the outside air have been realized. In addition, when storing a package containing a package containing a large amount of moisture and liquid components for a long period of time in a low temperature environment such as a room temperature to a refrigerator, the package loses moisture over time. In order to prevent the product from drying, a packaging material that is excellent in airtightness and more specifically has a small water vapor transmission amount is used.

  On the other hand, if the amount of water vapor permeated through the packaging material is excessively small, a large amount of water vapor is generated from the package in the package, such as packaging a high-temperature package or heating the package or package from the outside. When this occurs, the package may be deformed by volume expansion, the packaging material may be damaged in some cases, and the packaged material may be scattered and contaminate the external environment. Also, the water vapor generated condenses and condenses on the inner surface of the packaging material, and it reabsorbs or partially stays on the surface of the package, causing the water content to vary greatly depending on the site. It can cause quality degradation. Furthermore, since a partial increase in the amount of water can promote the growth of bacteria and the like, it causes inconveniences such as difficulty in long-term storage and restrictions on the storage conditions.

  For this reason, attempts have been made to form a large number of holes of several millimeters in the resin film used as a packaging material in order to increase the amount of water vapor permeation. Is only implemented in some applications where high sealability is not required.

On the other hand, in Patent Document 1, a laminate for bread packaging having a thermoplastic resin film having a water vapor permeability of 500 to 4000 g · 30 μm / (m ² · 24 h, 40 ° C. · 90% RH) on at least one side of the permeable substrate. A film has been proposed. And, according to the laminated film for bread packaging, internal water vapor can be appropriately released through the water vapor permeable thermoplastic resin film without excessively impairing the sealing performance, so that the inside of the foreign material can be suppressed while preventing the entry of foreign matter. It is described that water vapor can be released to suppress condensation inside the package and deformation of the package.

  In Patent Document 2, a urethane polymer film is laminated on at least one surface of the fiber fabric, the glass transition temperature of the urethane polymer film is in the range of 0 to 60 ° C., and A moisture-permeable waterproof fabric characterized in that the weight-average molecular weight of the polyurethane polymer is 15000 or more has been proposed. And since such a moisture-permeable waterproof fabric changes the amount of water vapor permeation depending on the outside air temperature, it is stated that if clothing is made using this, the body can be placed in a comfortable environment regardless of the outside air temperature. ing.

  On the other hand, in patent document 3, the food packaging material which laminated | stacked aluminum foil and paper is proposed. And, such a food packaging material can suppress the occurrence of moisture spots due to variation in the moisture content of the food in the package and the deterioration of the taste of the food by absorbing condensed water droplets etc. on the paper. Has been.

JP 2002-370320 A Japanese Patent No. 3074335 Japanese Patent No. 2882591

  However, the laminated film described in Patent Document 1 is specialized for bread packaging applications, and has a relatively high water vapor permeability, so that it can be used for packaging containing a large amount of moisture and liquid components. When packaging is carried out, depending on the storage environment and period, there is a problem in that water vapor in the package is gradually released, the packaged product is dried, and the quality of the packaged product can be deteriorated.

In addition, the moisture-permeable waterproof fabric described in Patent Document 2 is intended for apparel use, and cannot be diverted to the use for packaging a packaged object containing a large amount of water or liquid components for the following reasons. It was. That is, it is apparent from the examples that the moisture permeable waterproof fabric exhibits a moisture permeability of about 100 to 1000 g / (m ² · h) even in a low moisture permeable region. In addition, since the water vapor permeability is relatively high, if this is used to wrap a package containing a large amount of moisture or liquid components, depending on the storage environment and period, the water vapor in the package will gradually be released and the package will be wrapped. There was a problem that the product could be dried and the quality of the packaged product could be deteriorated. Furthermore, since the moisture-permeable waterproof fabric described in Patent Document 2 has high rigidity, when formed into a film, there is a problem that followability and adhesion to a packaged object to be packaged are poor, When molded into a container, there is a problem that the container shape cannot be maintained due to insufficient strength. Further, the moisture-permeable waterproof fabric described in Patent Document 2 has a problem that transparency is low and visibility is poor, and it is difficult to confirm the state of the packaged object to be packaged from the outside. Furthermore, the moisture-permeable waterproof fabric described in Patent Document 2 is inferior in surface smoothness, and the packaged material easily enters the voids on the fabric surface, so that the packaged material attached to the fabric surface has poor peelability. There was a problem.

  On the other hand, since the food packaging material described in Patent Document 3 has a paper layer to increase the amount of moisture absorbed, it has relatively high rigidity and does not have flexibility suitable for various packaging applications. Moreover, since the paper layer containing moisture may be spoiled by bacteria or the like and contaminate the package, there is a problem that the versatility is poor. In particular, in the case of a packaging form in which the paper layer can come into contact with the packaged object, there is a disadvantage that the paper layer can excessively absorb moisture and liquid components from the packaged object. In addition, when used repeatedly, the strength and the hygroscopicity of the paper layer are likely to fluctuate greatly, resulting in poor performance stability. Furthermore, the food packaging material described in Patent Document 3 has a problem that transparency is low and visibility is poor, and it is difficult to confirm the state of the packaged object from the outside of the package.

  The present invention has been made in view of such problems, and its purpose is to provide not only a packaged product having a low water content but also a packaged product containing a large amount of moisture and liquid components over a long period of time. New, unique and versatile, which can suppress excessive quality deterioration of the package, the packaged material in the package and the packaging material even if the temperature and humidity in the package change. It is providing the packaging material which is excellent in property, and its suitable usage method.

  As a result of intensive studies, the present inventors have found that the above problem can be solved by using a packaging material including at least one moisture permeation control layer in which the change in the amount of water vapor permeation due to temperature exhibits a specific behavior. The present invention has been completed.

That is, the present invention provides (1) to (5) below.
(1) Temperature (° C.)-Water vapor transmission rate W _VTR (g / g) obtained by molding a resin composition containing a thermoplastic resin and measured under a humidity condition of 60% RH in accordance with the JIS L1099 A-2 method. In the plot chart of (m ² · h)), the increase in the water vapor transmission rate W _VTR from the reference temperature T _S (° C.) to T _S +10 (° C.) is changed from T _S −10 ° C. (° C.) to the reference temperature T _S ( Moisture transition control having a transition region that is 2 to 100 times the increase in the water vapor permeation amount W _VTR of [° C.] and the reference temperature Ts (° C.) is in the range of 0 ° C. to 100 ° C. Comprising at least one layer,
Packaging material.

(2) Using the packaging material according to (1) above, a step of packaging an article to be packaged at a temperature equal to or lower than the reference temperature T _S ;
Heating the obtained package or the article to be packaged in the obtained package to a temperature region T ₂ higher than the reference temperature T _S ;
A method of using a packaging material having at least

(3) Using the packaging material according to (1) above, a step of packaging an article to be packaged having a temperature higher than the reference temperature T _S ;
Cooling the obtained package or the article to be packaged in the obtained package to a temperature region T ₁ equal to or lower than the reference temperature T _S ;
A method of using a packaging material having at least

(4) Using the packaging material described in (1) above, a step of packaging an article to be packaged at a temperature equal to or lower than the reference temperature T _S ;
At least an operation of cooling the resulting package or obtained the material to be packaged in the packaging body in to said reference temperature T _S below the temperature region T ₁ after heating to the reference temperature T _S higher than the temperature range T ₂ A step of performing at least once;
A method of using a packaging material having at least

(5) Using the packaging material according to (1) above, a step of packaging an article to be packaged having a temperature higher than the temperature region T _S ;
At least an operation of heating the resulting package or obtained the material to be packaged in the packaging body in to said reference temperature T a temperature higher than the _S region T ₂ after cooling to the reference temperature T _S below the temperature region T ₁ A step of performing at least once;
A method of using a packaging material having at least

  According to the present invention, a novel, unique and general-purpose product capable of preserving not only a packaged product having a low water content but also a packaged product containing a large amount of moisture and liquid components over a long period of time. A packaging material with excellent properties is realized. And even if temperature and the humidity in a package change according to this packaging material, the excessive quality degradation of a package, the to-be-packaged object in a package, and a packaging material can be suppressed, As a result, Decrease in the commercial value of a product and a packaged body in which the product is packaged can be suppressed for a long time.

  That is, the packaging material of the present invention is less than the transition region S, that is, in a relatively low temperature environment, has a small water vapor transmission amount and excellent water vapor barrier properties. Therefore, by using this to package an item to be packaged, a decrease in moisture over time when stored for a long time in a low temperature environment is sufficiently suppressed. Moreover, the packaging material of the present invention has a large water vapor transmission amount and excellent moisture permeability in the transition region S or more, that is, in a relatively high temperature environment. Therefore, even if a large amount of water vapor is generated in the package when the package is packaged using this, deformation of the package due to volume expansion, breakage of the package, and accompanying scattering of the package, packaging material Condensation on the inner surface and variation in the moisture content of the package are suppressed. Therefore, by using the packaging material of the present invention, it becomes possible to preserve a packaged article with high quality over a long period of time or to directly subject the package to heating and cooling. Furthermore, since the packaging material of the present invention can also have excellent moldability, excellent transparency (visibility), and excellent surface smoothness as compared with the prior art, films, molded articles, etc. It is possible to adopt various forms of the above, and to improve the designability in product display and the like.

It is a graph for demonstrating the temperature dependence of the water vapor transmission rate of a packaging material.

  Embodiments of the present invention will be described below. In addition, the following embodiment is an illustration for demonstrating this invention, and this invention is not limited only to the embodiment.

The packaging material of this embodiment is provided with at least one moisture permeation control layer formed by molding a resin composition containing a thermoplastic resin, and this moisture permeation control layer conforms to JIS L1099 A-2 method. In a plot chart of temperature (° C.)-Water vapor transmission rate W _VTR (g / (m ² · h)) measured under a humidity condition of 60% RH, from the reference temperature T _S (° C.) to T _S +10 (° C.) has a transition region S the increased amount of water vapor permeation amount W _VTR is T _S -10 ℃ (℃) reference temperature T _S (° C.) 100 times 2-fold increase of the water vapor permeation amount W _VTR follows from The reference temperature T _S (° C.) is in the range of 0 ° C. or more and 100 ° C. or less.

In this specification, the water vapor transmission amount W _VTR means a value measured in accordance with JIS L1099 A-2 method, and means a value measured under a humidity condition of 60% RH unless otherwise specified. To do. In addition, since the water vapor transmission amount shows temperature dependence in the packaging material of the present embodiment, the measurement of the water vapor transmission amount W _VTR needs to be performed with various temperatures set for each test, preferably It is carried out every 10 ° C., more preferably every 5 ° C.

  Moreover, in this specification, a packaging material means what is used in order to package a to-be-packaged object in order to preserve | save, move, process, protect, heat, cool, etc. of a to-be-packaged object. The form of the packaging material is not particularly limited, and an arbitrary form can be adopted depending on the purpose. For example, a film shape, a sheet shape, a bag shape, a molded product such as a lidded container or a box can be taken. Furthermore, in this specification, a package means the thing of the state by which the to-be packaged object was packaged with the packaging material. In addition, food is contained in the packaged goods. Here, food means all foods and drinks, and is a concept including ingredients, fresh foods, processed foods, functional foods, foods for specified health use, seasoning materials, food additives, and the like.

Moisture permeation control layer has a reference temperature T _S transition region S water vapor permeation amount W _VTR varies dramatically between the high-temperature region side and the low-temperature region side as a reference, this transition region S (reference temperature T _S) Is characterized in that the water vapor transmission amount W _VTR increases (decreases) specifically before and after. The transition region S includes an increase in the water vapor transmission rate W _VTR from the reference temperature T _S (° C.) to T _S +10 (° C.), and from the T _S −10 ° C. (° C.) to the reference temperature T _S (° C.). This is determined by comparing the increase in the water vapor transmission amount W _VTR .

In general, in the range of 0 ° C. or more and 100 ° C. or less, the moisture is in an equilibrium state between the liquid and the gas, and problems such as the drying of the articles to be packaged such as food and the dew condensation in the package occur in this range. Therefore, the reference temperature T _S needs to be set in the range of 0 ° C. or higher and 100 ° C. or lower, preferably in the range of 0 ° C. or higher and 80 ° C. or lower, more preferably in the range of 10 ° C. or higher and 60 ° C. or lower. . When the reference temperature T _S exceeds 100 ° C. and the reference temperature T _S is 0 ° C. or less, the fluctuation range of the water vapor transmission amount W _VTR within the temperature range of the practical packaging environment and storage environment is small. Since the functions of both the moisture release effect and the drying suppression effect cannot be compatible within the temperature range, it is not suitable as the packaging material of this embodiment. In addition, the storage temperature of the packaged goods during (long-term) storage converges near the storage environment temperature, and the storage time near the storage environment temperature occupies a large proportion. Therefore, in order to design with an emphasis on the drying suppression effect during long-term storage, it is preferable to set the reference temperature T _S to a temperature slightly higher than the recommended (long-term) storage environment temperature for each packaged object to be packaged. . On the other hand, to make a design that emphasizes the moisture release effect, such as when heating the package or the packaged item in the package with a microwave oven, other heating means or humidifying warming means before opening the reference temperature T _S is preferably set to a temperature slightly lower than the heating temperature of the objects to be packaged.

On the other hand, the increase in the water vapor transmission rate W _VTR from the reference temperature T _S (° C.) to T _S +10 (° C.) is the water vapor transmission rate W from T _S −10 ° C. (° C.) to the reference temperature T _S (° C.). It must be 2 to 100 times the increase in _VTR , preferably 2 to 50 times, more preferably 3 to 20 times. By thus water vapor permeation amount W _VTR changes suddenly as a boundary the reference temperature T _S, excellent water vapor barrier properties at low temperature side than the reference temperature T _S is an excellent water vapor transmission at a high temperature side than the reference temperature T _S And both functions of moisture release effect and drying suppression effect are compatible. If the difference in the increase amount of the water vapor transmission amount W _VTR exceeds 100 times, the water vapor transmission amount W _{VTR at a} temperature higher than the reference temperature T _S is too large, and the drying suppression effect of the package becomes insufficient. If it is less than double, the fluctuation range is small, so that both functions of the moisture release effect and the drying suppression effect cannot be achieved.

The water vapor transmission amount W _VTR (g / (m ² · h)) of the moisture permeation control layer at a temperature lower than the transition region S is preferably greater than 0 and 50 or less, more preferably 1 or more and 30 or less. More preferably, it is 5 or more and 20 or less. If the W _{VTR at} a temperature lower than the transition region S exceeds 50 (g / (m ² · h)), the water vapor barrier property is insufficient when packaging a package that cannot allow excessive variation in water content. In some cases, the effect of suppressing the drying of the package is not effectively exhibited, and even in a relatively low temperature environment, the moisture of the package is lost rapidly and the function required as a packaging material cannot be sufficiently achieved.

The moisture permeation control layer exhibits a specific behavior in which the water vapor transmission amount W _VTR (g / (m ² · h)) changes dramatically with the transition region S as a boundary. In other words, the moisture permeation control layer functions as a water vapor barrier layer by exhibiting an excellent drying suppression effect until just before the reference temperature T _S , while the moisture release effect suddenly appears as the reference temperature T _S is exceeded. Functions as a water vapor permeable membrane. The reason why the packaging material of the present embodiment exhibits the moisture permeation control effect optimized for the packaging of an object to be packaged such as food can be explained as follows.

FIG. 1 is a plot chart of temperature (° C.) − Water vapor transmission rate W _VTR (g / (m ² · h)) measured under a humidity condition of 60% RH in accordance with JIS L1099 A-2 method. The water vapor permeability of the conventional packaging material shows the behavior of dotted line a or dotted line c in the figure. In the case of a porous packaging material formed of a dotted line a, for example, a nonwoven fabric or paper, it has a sufficient amount of water vapor permeation in a region higher than the reference temperature T _S , so that water vapor is filled in the package at a high temperature. Although it is unlikely to cause problems such as expansion of the package or condensation on the inner surface of the packaging material, the water vapor permeation amount is large even in the temperature range below the reference temperature T _S, so that it is packaged when stored for a long time. When the product is dried, or the packaged product is a food, the original flavor and texture of the food are impaired, and foreign matters are likely to be mixed. Moreover, when it is what is shown by the dotted line c, for example, the commercially available food packaging wrap made of polyethylene, the packaging container made of polypropylene, etc., the water vapor permeability at the temperature below the reference temperature T _S is low and the water vapor barrier property is excellent. Therefore, it is difficult to cause problems such as drying of the package or mixing of foreign substances when stored for a long time, but the package is heated because the amount of water vapor transmission is small even in the temperature range above the reference temperature T _S. The water vapor generated during the process cannot be fully released from the inside of the package to the outside world, and the package body expands, the packaging material expands, the packaging material breaks, or condensation forms on the inner surface of the packaging material. It may be difficult to avoid problems such as deteriorating, and may cause deterioration of handling property due to enlargement of the package, reduction of safety due to ejection of internal high-temperature steam, and the like. Table 1 specifically shows an example of the behavior of the water vapor transmission amount W _VTR (g / (m ² · h)) of the above-described typical representative packaging material.

注１）０℃以上１００℃以下の範囲内に水蒸気透過量Ｗ_VTRが飛躍的に増大する特異点を有さず、遷移領域Ｓが存在しない。このような挙動を示す包装材を用いて中心温度８０℃のおにぎりを包装した後に２０℃にて８時間保管した場合、乾燥が生じ食味が損なわれ易く、そればかりか、異物が混入し易い。このような挙動を呈する包装材は、例えば、コットンリンターの再生セルロースをスパンボンド法により１０〜５０ｇ／ｍ²の坪量の不織布を形成することにより得ることができる。
注２）０℃以上１００℃以下の範囲内に水蒸気透過量Ｗ_VTRが飛躍的に増大する特異点を有さず、遷移領域Ｓが存在しない。このような挙動を示す包装材を用いて中心温度８０℃のおにぎりを包装した後に２０℃にて８時間保管した場合、包装材の内面に結露が発生して食味が損なわれ易い。このような挙動を呈する包装材は、例えば、軟質ポリ塩化ビニル樹脂等を融点以上で熱溶融して広幅のスリットから押し出して約５〜５０μｍ程度の厚みに製膜することにより得ることができる。

Note 1) There is no singular point where the water vapor transmission rate W _VTR dramatically increases within the range of 0 ° C. or higher and 100 ° C. or lower, and the transition region S does not exist. When packaging a rice ball with a central temperature of 80 ° C. using a packaging material exhibiting such behavior and storing it at 20 ° C. for 8 hours, drying tends to occur and the taste is likely to be impaired, as well as foreign matters are likely to be mixed. A packaging material exhibiting such a behavior can be obtained, for example, by forming a nonwoven fabric having a basis weight of 10 to 50 g / m ² by using a spunbond method of regenerated cellulose of cotton linter.
Note 2) There is no singular point where the water vapor transmission rate W _VTR dramatically increases in the range of 0 ° C. or higher and 100 ° C. or lower, and the transition region S does not exist. When a rice ball with a central temperature of 80 ° C. is packaged using a packaging material exhibiting such a behavior and then stored at 20 ° C. for 8 hours, condensation is likely to occur on the inner surface of the packaging material, and the taste tends to be impaired. A packaging material exhibiting such behavior can be obtained, for example, by thermally melting a soft polyvinyl chloride resin or the like at a melting point or higher and extruding it from a wide slit to form a film having a thickness of about 5 to 50 μm.

On the other hand, the water vapor permeability of the packaging material of this embodiment shows the behavior of the solid line b in the figure. As described above, the packaging material of the present embodiment has a sufficiently small amount of water vapor permeation in a temperature range equal to or lower than the reference temperature T _S , so that moisture release from the package body to the outside is suppressed, and as a result, the package is dried. Is suppressed. At this time, the humidity in the package can be increased in the temperature range below the reference temperature T _S, but the amount of water vapor generated is relatively small because it is in a relatively low temperature environment, and even if condensed water droplets are generated, the taste is good. There is no impact on hygiene and is negligible. On the other hand, as described above, the packaging material of the present embodiment has a water vapor permeability that increases the amount of water vapor as the temperature rises from the vicinity of the reference temperature T _S , and can quickly release the generated water vapor. For this reason, it is difficult for condensation to occur on the inner surface of the packaging material, and adverse effects on the packaged object due to water droplets generated by the condensation and expansion of the package are suppressed. Table 2 specifically shows a behavior example of the water vapor transmission amount W _VTR (g / (m ² · h)) of the packaging material of the present embodiment.

注３）５０〜７０℃に遷移領域Ｓが存在し、基準温度Ｔ_Sが６０℃に存在する。このような挙動を示す包装材を用いて中心温度８０℃のおにぎりを包装した後に２０℃にて８時間保管した場合、結露の発生、被包装物の乾燥、食味の悪化、異物の混入は生じ難い。また、上記従来の不織布等の包装材に比して、視認性（透明性）、形状追従性、剥離性、繰り返し使用の耐久性にも優れる。このような挙動を呈する包装材は、例えば、スチレン・ブタジエン共重合高分子（旭化成ケミカルズ株式会社製樹脂、商品名「アスマー」）を、融点以上で熱溶融して広幅のスリットから押し出して約５〜５０μｍ程度の厚みに製膜することにより得ることができる。
注４）２５〜４５℃に遷移領域Ｓが存在し、基準温度Ｔ_Sが３５℃に存在する。このような挙動を示す包装材を用いて中心温度８０℃のおにぎりを包装した後に２０℃にて８時間保管した場合、結露の発生、被包装物の乾燥、食味の悪化、異物の混入は生じ難い。また、上記従来の不織布等の包装材に比して、視認性（透明性）、形状追従性、剥離性、繰り返し使用の耐久性にも優れる。このような挙動を呈する包装材は、例えば、４，４’−ジフェニルメタンジイソシアネートとポリプロピレングリコールを共重合させて得たウレタンプレポリマーをエチレングリコールと反応させて得られるウレタン系高分子を、融点以上で熱溶融して広幅のスリットから押し出して約５〜５０μｍ程度の厚みに製膜することにより得ることができる。

Note 3) The transition region S exists at 50 to 70 ° C., and the reference temperature T _S exists at 60 ° C. When packaging rice balls with a central temperature of 80 ° C using a packaging material exhibiting such behavior and storing them at 20 ° C for 8 hours, condensation will occur, the package will dry, the taste will deteriorate, and foreign matter will be mixed in. hard. Moreover, it is excellent in visibility (transparency), shape followability, peelability, and durability for repeated use as compared with the conventional packaging materials such as nonwoven fabrics. The packaging material exhibiting such a behavior is, for example, about 5 by extruding a styrene / butadiene copolymer polymer (resin made by Asahi Kasei Chemicals Co., Ltd., trade name “Asmer”) above the melting point and extruding it from a wide slit. It can be obtained by forming a film to a thickness of about ˜50 μm.
Note 4) The transition region S exists at 25 to 45 ° C., and the reference temperature T _S exists at 35 ° C. When packaging rice balls with a central temperature of 80 ° C using a packaging material exhibiting such behavior and storing them at 20 ° C for 8 hours, condensation will occur, the package will dry, the taste will deteriorate, and foreign matter will be mixed in. hard. Moreover, it is excellent in visibility (transparency), shape followability, peelability, and durability for repeated use as compared with the conventional packaging materials such as nonwoven fabrics. The packaging material exhibiting such behavior is, for example, a urethane polymer obtained by reacting a urethane prepolymer obtained by copolymerizing 4,4′-diphenylmethane diisocyanate and polypropylene glycol with ethylene glycol at a melting point or higher. It can be obtained by heat melting and extruding from a wide slit to form a film having a thickness of about 5 to 50 μm.

  The moisture permeation control layer of the packaging material of this embodiment can be obtained by molding a resin composition containing a thermoplastic resin. More specifically, using a thermoplastic resin obtained by polymerizing or blending a plurality of components having different glass transition temperatures, melting points, crystallinity, molecular weight, molecular chain length, steric structure, molecular gap, polarity, hydrophilicity, etc. By molding a resin composition containing such a thermoplastic resin, a moisture permeation control layer in which water vapor permeability (temperature dependence of water vapor transmission amount) is controlled within the above range can be easily obtained.

  Although it does not specifically limit as a specific example of the thermoplastic resin which comprises a moisture-permeable control layer, For example, the copolymer (preferably a block copolymer or a graft copolymer) which consists of 2 or more types of monomers, 1 type Polymers comprising the above prepolymers and one or more monomers (preferably block copolymers or graft copolymers), polymer blends of two or more polymers (including physical blends, chemical blends, polymer alloys) And a polymer complex of two or more kinds of polymers. The reason why the water vapor permeability of the moisture permeation control layer is adjusted within the above range cannot be unambiguously described because various factors are intertwined. However, the moisture permeation control layer is mainly composed of a thermoplastic resin. Due to the chemical properties, physical properties, and thermal properties of the multiple components that comprise, for example, partially having a crystalline structure and an amorphous structure, soft units (soft segments) and hard units (hard segments) This is presumably due to non-uniform construction. Therefore, as illustrated, it is preferable to use a thermoplastic resin capable of easily constructing the soft unit and the hard unit when forming the moisture permeation control layer.

A method for controlling the water vapor permeability (water vapor transmission amount, temperature dependency of water vapor transmission amount, reference temperature T _S ) of the moisture permeation control layer is not particularly limited, and any method can be adopted. For example, glass transition temperature, melting point, crystallinity, molecular weight, molecular chain length, three-dimensional structure, molecular gap, polarity, hydrophilicity, etc. of each component constituting the thermoplastic resin, blending ratio of multiple components, melting during molding Alternatively, the water vapor permeability of the moisture permeation control layer can be controlled by appropriately adjusting the cooling conditions (temperature, time, process management, etc.), the thickness of the film or sheet during molding, the thickness of the molded body, and the like.

For example, in the case where T _S is determined using the difference in glass transition temperature, it is presumed that the control of the water vapor transmission amount can be explained as follows. That is, normally, the soft unit has a glass transition point lower than that of the hard unit, and above the glass transition temperature, the micro-Brownian motion of the molecule is activated, the molecular gap is increased, and the water vapor transmission rate is remarkably increased. On the other hand, at the same temperature, there is almost no change in the physical characteristics of the hard unit, and the rigidity and shape can be maintained. Therefore, the moisture permeation control layer in which these are present in a non-uniform manner maintains the shape and rigidity required as a packaging material due to the characteristics of the hard unit in a high temperature environment higher than the glass transition temperature of the soft unit, while at the same time A significant increase in quantity can be caused by the properties of the soft unit. In general, the higher the blending ratio of the hard unit, the higher the glass transition temperature as a whole, and the higher the molecular weight of the components constituting the hard unit and the soft unit, the lower the glass transition temperature. As the three-dimensional rigidity increases, the glass transition point becomes higher. As the hydrophilicity of each component increases, the amount of water vapor transmission increases, and as the activity of the soft brown of the soft unit increases, the amount of increase in the amount of water vapor transmission tends to increase. Therefore, it is possible to precisely control the water vapor permeability of the moisture permeation control layer by adjusting the combination and blending ratio of each component constituting the thermoplastic resin.

Although it does not specifically limit as a specific example of the copolymer which consists of 2 or more types of monomers, For example, the styrene-butadiene copolymer which is a styrene-type alloy is mentioned. In this case, for example, polystyrene is used as a hard unit that melts at a high temperature of about 120 ° C. and hardly changes in shape and rigidity at a temperature lower than that. By adopting the crystalline polybutadiene whose permeability is remarkably increased as a soft unit, it is possible to realize the moisture permeation control layer of the present embodiment in which a change in the amount of water vapor permeation due to temperature exhibits a specific behavior. In such a styrene-butadiene copolymer, for example, by changing the blending ratio of polystyrene and crystalline polybutadiene, the fluctuation amount of the water vapor transmission amount W _VTR around the reference temperature T _S can be arbitrarily adjusted.

Specific examples of the polymer composed of one or more prepolymers and one or more monomers are not particularly limited. For example, a polyisocyanate represented by the general formula OCNR ₁ NCO and a diol represented by HOR ₂ OH are co-polymerized. Urethane polymer OCN [(R ₁ NHCOOR ₂ OCONH) _m (R ₁ NHCOOR ₃ OCONH) _n ] _l R obtained by reacting a urethane prepolymer obtained by polymerization with a chain extender represented by HOR ₃ OH ₁ NCO [wherein m, n and l represent a positive integer, particularly preferably 1 to 16]. Such a polyurethane-based polymer does not become a completely uniform state at the molecular level, and is composed of a soft segment composed of a non-crystalline diol unit and a hard segment composed of a chain extender and a polyisocyanate. It is conceivable that the glass transition temperature and the water vapor transmission characteristics may vary depending on the rigidity of R ₁ , R ₂ , R ₃ , molecular weight, steric structure, polarity, hydrophilicity, etc., as well as the number of m and n. That is, the glass transition temperature becomes lower as the molecular weight of R _2, R ₃ is increased, in R _1, R _2, a glass transition temperature higher rigidity of the R ₃ increases increases tendency. In addition, the higher the hydrophilicity of R ₁ , R ₂ , and R ₃ , the greater the amount of water vapor transmission, and the higher the activity of micro Brownian motion, such as the longer molecular chain length of R ₃ , the water vapor transmission amount at the glass transition temperature. The range of increase tends to increase. Therefore, in such a polyurethane polymer, by combining these in consideration, the fluctuation amount of the water vapor transmission amount W _VTR around the reference temperature T _S and the reference temperature T _S can be precisely adjusted. It is possible to realize the moisture permeation control layer of this embodiment in which the change in the amount of water vapor permeation due to temperature exhibits a specific behavior.

  Although it does not specifically limit as a specific example of polyisocyanate, For example, what has two or more isocyanate groups at the terminal, More specifically, 2, 4- toluene diisocyanate, 4,4'- diphenylmethane diisocyanate, carbodiimide modification | denaturation 4,4′-diphenylmethane diisocyanate, hexamethylene diisocyanate, prepolymer type polyisocyanate, and the like. These can be used individually by 1 type or in mixture of 2 or more types.

  Although it does not specifically limit as a specific example of diol, For example, what has two or more hydroxyl groups in a molecule | numerator, More specifically, polypropylene glycol, 1, 4- butane glycol adipate, polytetramethylene glycol, bisphenol A + Examples include polyether polyols such as propylene oxide, polyester polyols, and polyether polyester polyols obtained by polymerizing these. These can be used individually by 1 type or in mixture of 2 or more types.

  Specific examples of the chain extender are not particularly limited. For example, ethylene glycol, diethylene glycol, propylene glycol, 1,4-butane glycol, bis (2-hydroxyethyl) hydroquinone, bisphenol A + ethylene oxide, bisphenol A + propylene oxide, and the like. Is mentioned. These can be used individually by 1 type or in mixture of 2 or more types.

  Specific examples of the polymer blend of two or more polymers and the polymer complex of two or more polymers are not particularly limited. For example, styrene-based, olefin-based, ester-based, amide-based, carbonate-based polymer blends, polymer alloys More specifically, for example, polyamide / polypropylene, polyamide / elastomer, polycarbonate / polystyrene, polycarbonate / polypropylene, polycarbonate / polybutylene terephthalate, polycarbonate / polyethylene terephthalate, modified polyphenylene ether, ABS / polyolefin and These combinations and the like can be mentioned. These can be used individually by 1 type or in mixture of 2 or more types.

  In addition to the above, examples of the material having a crystalline / non-crystalline part include a polyvinyl chloride part having a crystalline polyvinyl chloride part and an amorphous polyvinyl chloride part. In this case, the crystalline polyvinyl chloride part functions as a hard unit, and the amorphous polyvinyl chloride part functions as a soft unit. Conceivable. Examples of a material that exhibits the same effect include viscose, transisoprene, polynorbornene, and polybutadiene rubber.

  The resin composition containing a thermoplastic resin may contain other components as necessary. Other components are not particularly limited and are known additives such as surfactants, antioxidants, heat stabilizers, flame retardants, internal mold release agents, antiblocking agents, antistatic agents, plasticizers, lubricants. , Ultraviolet absorbers, infrared absorbers, pigments, various solvents and the like.

  In molding a moisture permeation control layer from a resin composition containing a thermoplastic resin, a known thermoplastic resin film forming / molding method or the like can be used. Specific examples include a solution cast molding method, a T-die method, a cutting method, an inflation method, an injection molding method, a blow molding method, a pressure forming method, a vacuum molding method, a foam molding method, and the like. It is not limited.

  The thickness of the moisture permeation control layer is not particularly limited, and is appropriately set according to the required water vapor permeability. In general, as the thickness of the moisture permeation control layer increases, the water vapor permeability tends to decrease. On the other hand, as the moisture permeation control layer decreases, the water vapor permeability tends to increase. ) And shape followability tend to be improved.

  Even if the packaging material has the above-described configuration of the moisture permeation control layer alone, it has a configuration in which another functional layer is partially or entirely provided on one or both sides of the moisture permeation control layer formed into a film or sheet. Alternatively, the moisture permeation control layer may be configured to include another functional layer, or the moisture permeation control layer may be integrated with the other functional layer.

  Specific examples of the functional layer are not particularly limited. For example, in addition to silicone resins, fluororesins, superabsorbent resins, elastomers such as natural rubber and synthetic rubber, natural fibers, synthetic fibers or semi-synthetic fibers are used. Nonwoven fabric, woven fabric, paper, etc. By adopting a laminated structure with such a functional layer, it is possible to impart or improve functions such as adhesiveness, slipperiness, water absorption, oil absorption, releasability, adhesion, etc. The utility value as a highly functional packaging material is increased.

The functional layer preferably has a water vapor transmission amount W _VTR (g / (m ² · h)) that is always larger than that of the moisture permeation control layer over the entire temperature range of 0 to 100 ° C. Water vapor permeability of W _VTR of the functional layer ^{(g / (m 2 · h} )) water vapor permeability of the entire wrapper is less than moisture permeable control layer ^{_{W VTR (g / (m 2}} · h)) is functional layer Since it can be controlled, the moisture permeation control effect of the moisture permeation control layer may not be sufficiently exhibited. Moreover, it is preferable that a functional layer is a thing with poor hygroscopicity. If the hygroscopicity of the functional layer is high, it is difficult to adjust the moisture permeability at the time of use, and thus the moisture permeability control effect of the moisture permeability control layer may not be sufficiently exhibited.

  It is desirable that the packaging material does not contain a fabric. If the packaging material includes a fabric, the fabric is opaque and it is difficult to visually recognize the packaged item in the package from the outside. Can occur. In addition, when the packaging material containing the fabric is in the form of a film or sheet, the thickness and rigidity of the fabric impairs flexibility and shape following at the time of molding or handling of the film or sheet, resulting in production. , Handling properties and versatility tend to decrease. On the other hand, when the packaging material containing the fabric is a container-shaped molded body, the flexibility of the fabric makes it difficult to maintain the shape when the molded body is molded or when it is handled after molding, resulting in productivity and shape stability. And dimensional stability tends to be lowered. Furthermore, since the fabric has irregularities on the surface and is poor in smoothness and inferior in peelability, problems such as invasion of an article to be packaged in the package into a void on the surface of the fabric may occur during packaging or storage. Moreover, since the fiber which comprises a cloth may drop | omit and mix in a to-be-packaged object, the use as a packaging material may be restrict | limited.

  The method of forming the functional layer is not particularly limited. For example, a method of laminating or integrating a functional layer separately formed into a sheet shape with an adhesive or heat and laminating or integrating the moisture permeability control layer formed into a film shape or a sheet shape , A method of laminating or integrating a molten functional layer directly onto a moisture permeation control layer formed into a film or sheet and forming a film, or applying or spraying a functional layer separately dissolved in a solution to the moisture permeation control layer Examples thereof include a method of drying and then laminating or integrating, and a method of laminating or integrating the functional layer on the moisture permeation control layer by coextrusion or vapor deposition.

  As described above in detail, the packaging material of the present embodiment is not only a packaged product having a low water content such as bread, but also a packaged product containing a large amount of moisture and liquid components over a long period of time. For example, it can be suitably used as a packaging material for packaging foods containing cooked, steamed or fermented rice or grains. For example, rice balls are usually molded at a high temperature of about 60 to 90 ° C., and after being radiated for a certain period of time in order to maintain the flavor, the rice balls are often stored and transported as they are. Since the packaging material of the embodiment has both functions of a moisture release effect at a relatively high temperature and a drying suppression effect at a relatively low temperature, the process of radiating heat can be omitted by using this. Can be packaged. Therefore, by using the packaging material of the present embodiment, the process tolerance is dramatically increased, and as a result, productivity and economy are improved.

Hereinafter, the preferable usage method of the packaging material of this embodiment is explained in full detail.
A preferred first method of use is to wrap a packaged object having a temperature equal to or lower than the reference temperature T _S using the packaging material of the present embodiment, and use the obtained packaged body or the packaged object in the obtained packaged body as a reference. This is a method of heating to a temperature region T ₂ higher than the temperature T _S. A specific example of such a method of use is not particularly limited. For example, in the case where a food at room temperature is heated in a cooker such as a microwave oven after packaging, is the frozen food heated in a cooker after packaging? In case of thawing by leaving at room temperature or the like, in case of heating a wet cloth after packaging and making a steamed towel, etc. are mentioned. The unpacking of the package can be performed in either the temperature region T _{1 or the} temperature region T ₂ .

A preferred second method of use is to wrap a package object having a temperature higher than the reference temperature T _S using the packaging material of the present embodiment, and to reference the obtained package object or the package object in the obtained package object. This is a method of cooling to a temperature region T ₁ below the temperature T _S. A specific example of such a method of use is not particularly limited. For example, when the food immediately after cooking is packaged and stored in a refrigerator or freezer, a room temperature environment is obtained after packaging a high temperature liquid or gel. In the case of leaving it down or moving it in a room temperature environment, and the like. The unpacking of the package can be performed in either the temperature region T _{1 or the} temperature region T ₂ .

A preferred third usage method is to use the packaging material of the present embodiment to wrap a packaged material having a temperature equal to or lower than the reference temperature T _S , and to obtain the packaged product or the packaged product in the obtained packaged product. the operation of cooling to a temperature region T ₁ below the reference temperature T _S after heating to the reference temperature T _S higher than the temperature range T ₂ is a method of performing at least once. If dew condensation occurs on the inner surface of the packaging material, local heating spots are likely to occur during heating, and the intended high-quality preservation becomes difficult to perform when using a packaging material that has been elongated due to breakage or formed with holes, etc. For this reason, when the packaging body repeatedly experiences the temperature region T ₁ and the temperature region T ₂ as described above, the packaging material of the present embodiment having both functions of a moisture release effect and a drying suppression effect is superior. Become prominent. Specific examples of such a method of use are not particularly limited. For example, when a food is once heated after packaging and then recooled for the purpose of preparation by mixing with a low temperature food, packaging a wet fabric is performed. In the case of later heating and sterilizing and disinfecting, and further re-cooling for the purpose of using as a hygienic water-containing fabric or providing a cold spring, etc. The unpacking of the package can be performed in either the temperature region T _{1 or the} temperature region T ₂ .

A preferred fourth method of using the packaging material of the present embodiment is to package a packaged material having a temperature higher than the temperature region T _S , and obtain the packaged product or the packaged product in the obtained packaged product. the operation of heating after cooling to the reference temperature T _S below the temperature region T ₁ to the reference temperature T a temperature higher than the _S region T ₂ is a method of performing at least once. If dew condensation occurs on the inner surface of the packaging material, local heating spots are likely to occur during heating, and the intended high-quality preservation becomes difficult to perform when using a packaging material that has been elongated due to breakage or formed with holes, etc. For this reason, when the packaging body repeatedly experiences the temperature region T ₁ and the temperature region T ₂ as described above, the packaging material of the present embodiment having both functions of a moisture release effect and a drying suppression effect is superior. Become prominent. Although it does not specifically limit as a specific example of such a usage method, For example, when packaging the food immediately after heat cooking, it preserve | saves in a refrigerator, and also heats before a meal etc. are mentioned. The unpacking of the package can be performed in either the temperature region T _{1 or the} temperature region T ₂ .

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not restrict | limited to these.

[Example 1]
A styrene-butadiene copolymer polymer (resin made by Asahi Kasei Chemicals Co., Ltd., trade name “Asmer”) is melted at a temperature equal to or higher than the melting point to form a sheet by a T-die method, and then 15 cm in thickness of 1 mm by vacuum / pressure forming. A square packaging container was obtained. In this container, a transition region S having a reference temperature T _S (° C.) of 60 ° C. is confirmed, and the amount of water vapor transmission W _VTR in the range of 60 to 70 ° C. is the amount of water vapor transmission in the range of 50 to 60 ° C. The increase in W _VTR was about 8 times.

[Example 2]
Urethane obtained by copolymerizing 4,4'-diphenylmethane diisocyanate, which is a diisocyanate component, and polypropylene glycol, which is a long chain diol component, to obtain a urethane prepolymer, and reacting this urethane prepolymer with ethylene glycol, which is a chain extender. A high molecular weight polymer (glass transition point Tg = 35 ° C.) was thermally melted at a melting point or higher and extruded from a wide slit to form a film having a thickness of 30 μm to obtain a packaging film. In this film, a transition region S having a reference temperature T _S (° C.) of 30 to 35 ° C. was confirmed.

[Comparative Example 1]
As a packaging material of Comparative Example 1, a commercially available food packaging wrap made of polyethylene resin (trade name “NEW Rose wrap”, manufactured by CI Kasei Co., Ltd.) was used. This film did not have the reference temperature T _S and the transition region S in the temperature range of 0 to 100 ° C., and the water vapor transmission amount W _VTR was always lower than 50 (g / (m ² · h)).

[Comparative Example 2]
As the packaging material of Comparative Example 2, a non-woven fabric made of regenerated cellulose fibers of cotton linter formed to a basis weight of 30 g / m ² by the spunbond method was used. This nonwoven fabric did not have the reference temperature T _S and the transition region S in the temperature range of 0 to 100 ° C., and the water vapor transmission amount W _VTR always exceeded 50 (g / (m ² · h)).

Table 3 shows the water vapor permeation amount W _VTR of the packaging materials of Examples and Comparative Examples.

(Performance evaluation 1)
After packaging a 15 ° C. water-containing towel having a temperature equal to or lower than the reference temperature T _S of the packaging material of Example 1, it was heated to about 80 ° C. in a microwave oven for 2 minutes. Table 4 shows the observation results and evaluation results of the package and the package.

(Performance evaluation 2)
After packaging a rice ball with a center temperature of 80 ° C., which is higher than the reference temperature T _S of the packaging material of Example 2, it was stored at room temperature for 12 hours. Table 5 shows the observation results and evaluation results of the package and the package.

(Performance evaluation 3)
The baby bottle is packaged at room temperature (20 ° C.), which is equal to or lower than the reference temperature T _S of the packaging material of Example 2, and heated to about 100 ° C. for 5 minutes in a microwave oven for the purpose of sterilization. Stored for 8 hours. Table 6 shows the observation results and evaluation results of the package and the package.

(Performance evaluation 4)
The bun just after cooking heated to 100 ° C., which is higher than the reference temperature T _S of the packaging material of Example 1, is packaged, stored in the refrigerator for 8 hours, and then heated in a microwave oven for 2 minutes. The temperature was raised to 80 ° C. Table 7 shows the observation results and evaluation results of the package and the packaged objects.

Here, each evaluation standard in the performance evaluation was as follows.
[1] Condensation After unpacking and removing the package after the test, the weight of water droplets adhering to the inner surface of the packaging material is measured, and if it is ² g / m ² or less, “no condensation” is 2 g / m Those exceeding ² were rated as “condensation”.
[2] Drying of packaged object The surface layer of the packaged object before and after the test was sampled at 5 locations in a 1 cm ² square, and the moisture content measured with an infrared moisture meter (FD-240 manufactured by Kett Chemical Laboratory Co., Ltd.) was measured. The average values were compared, and when the decrease rate before and after the test was 20% or less, “no drying” was evaluated, and when the decrease rate exceeded 20%, “drying” was evaluated.
[3] Presence / absence of foreign matter The surface of the object to be packaged before and after the test was visually observed, and the presence / absence of dust, packaging material, and the like was evaluated.
[4] Taste Tens of panelists who ate the packaged food after the test and scored in five stages sensuously with 5 as the one that had no texture such as partial dryness or wisdom, etc. The average evaluation of 4 or more was evaluated as ◎, 2.5 or more as ○, and less than 2.5 as ×.
[5] Moisture spots The surface layer of the package after the test was sampled at 5 locations in a 1 cm 2 square, and the variation in the moisture content measured with an infrared moisture meter (FD-240 manufactured by Kett Chemical Laboratory Co., Ltd.) was an average. The case where the value was within ± 20% of the value was evaluated as “no water spots”, and the case where it was distributed over 20% was evaluated as “water spots”.
[6] Offensive odor Sensory evaluation of the wrapping after testing and the presence or absence of spoiled odor or foul odor. Eight out of 10 panelists judged that there was no off-flavor. When it was, it was evaluated as “abnormal odor”.
[7] Ease of opening Sensory evaluation was conducted for the presence or absence of problems such as being difficult to peel off when closely unpacked after unpacking after testing. When the number of people judged to be no problem was evaluated as ○, and when the number of people judged as no problem was 5 or less, it was evaluated as ×.
[8] Deformation of packaging material The package during heating was visually observed from the outside, and the presence or absence of a change in the shape of the package was evaluated.
[9] Destruction of packaging material The packaging material after the test was visually confirmed, and the presence or absence of holes, cracks, dissolution, and tearing was evaluated.
[10] Spout of water vapor The packaging body being heated was visually observed from the outside, and for those with a severe outflow of water vapor from the packaging body, the presence or absence of destruction of the packaging material after the test was observed, and there was destruction. The thing was evaluated as “with water vapor spout”.

  As is clear from Tables 4 to 7, in the packaging materials shown in the examples, the effect of suppressing condensation due to the improvement of water vapor permeability at high temperatures, the effect of reducing the pressure inside the package, and the effect of suppressing destruction of the packaging material. And other features such as high barrier properties due to a decrease in water vapor permeability at low temperatures, and a deformation-inhibiting effect. It turns out that the outstanding effect is demonstrated.

  The packaging material of the present invention has both functions of a moisture releasing effect at a relatively high temperature and a drying inhibiting effect at a relatively low temperature, and not only a packaged product having a low water content but also a large amount of moisture and Since the package containing liquid components can be stored in high quality for a long period of time, or the package can be subjected to heating and cooling as it is, storage, movement, processing, protection, heating, As a material used for cooling, it can be used widely and effectively. In particular, it can be used widely and particularly effectively in a packaged product containing a large amount of water and liquid components, for example, food packaging.

Claims (5)

A temperature (° C.)-Water vapor transmission rate W _VTR (g / (m ² ) obtained by molding a resin composition containing a thermoplastic resin and measured under a humidity condition of 60% RH in accordance with JIS L1099 A-2 method. In the plot chart of h)), the increase in water vapor transmission rate W _VTR from the reference temperature T _S (° C.) to T _S +10 (° C.) is from T _S −10 ° C. (° C.) to the reference temperature T _S (° C.). At least a moisture permeation control layer having a transition region that is 2 to 100 times the increase in water vapor transmission rate W _VTR and that has a reference temperature Ts (° C.) in the range of 0 ° C. to 100 ° C. It is characterized by having one more layer,
Packaging material. Using the packaging material according to claim 1, a step of packaging an article to be packaged at a temperature equal to or lower than the reference temperature T _S ;
Heating the obtained package or the article to be packaged in the obtained package to a temperature region T ₂ higher than the reference temperature T _S ;
A method of using a packaging material having at least Using the packaging material according to claim 1 to package a packaged object having a temperature higher than the reference temperature T _S ;
Cooling the obtained package or the article to be packaged in the obtained package to a temperature region T ₁ equal to or lower than the reference temperature T _S ;
A method of using a packaging material having at least Using the packaging material according to claim 1, a step of packaging an article to be packaged at a temperature equal to or lower than the reference temperature T _S ;
At least an operation of cooling the resulting package or obtained the material to be packaged in the packaging body in to said reference temperature T _S below the temperature region T ₁ after heating to the reference temperature T _S higher than the temperature range T ₂ A step of performing at least once;
A method of using a packaging material having at least Using the packaging material according to claim 1, packaging a packaged object having a temperature higher than the temperature region T _S ;
At least an operation of heating the resulting package or obtained the material to be packaged in the packaging body in to said reference temperature T a temperature higher than the _S region T ₂ after cooling to the reference temperature T _S below the temperature region T ₁ A step of performing at least once;
A method of using a packaging material having at least

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