JP5802033B2 - Packaging film, laminated packaging film, method for producing the film, and packaging method using the film - Google Patents

Description

  The present invention relates to a film useful as a packaging film.

  Since 4-methyl-1-pentene polymer has a bulky functional group, it has a lower density than other thermoplastic olefin films. For this reason, a film containing 4-methyl-1-pentene polymer has high gas permeability such as oxygen gas and carbon dioxide gas, and is being developed as a gas permeable film for packaging materials such as fresh food (for example, Patent Document 1).

  A film containing 4-methyl-1-pentene polymer is suitable for MA packaging (Modified Atmosphere Packaging) because there is a difference in gas permeability between oxygen gas and carbon dioxide gas. The MA packaging changes the gas composition inside the package, which has been changed by oxygen gas consumption and carbon dioxide accumulation caused by the respiration of fruits and vegetables, to a lower oxygen gas concentration and a higher carbon dioxide concentration than the atmosphere. This is a packaging method that suppresses the action and maintains the freshness. For this reason, a gas permeable film containing 4-methyl-1-pentene polymer having a gas selective permeability of carbon dioxide gas permeability lower than oxygen gas permeability is said to be suitable for MA packaging. (For example, Patent Document 2).

  On the other hand, the packaging film requires not only gas permeability but also seal strength at the time of packaging, and easy peelability that allows the film to be peeled off at the bonding part without causing damage or cracking when the packaging film is peeled off. (Hereinafter, having both high sealing strength and easy peel property is also referred to as heat sealing property).

  4-Methyl-1-pentene polymer has a high melting point and low heat seal strength. In addition, since the toughness (toughness) is low, breakage and cracks are likely to occur at the bonded portion during handling of the film or peeling of the film. For this reason, development of a packaging film containing a 4-methyl-1-pentene polymer having both gas permeability and heat sealability has been studied. Specifically, it is considered to provide heat sealability by laminating a thermoplastic resin such as polyethylene or polypropylene having a low melting point as a heat seal layer on a gas permeable layer containing 4-methyl-1-pentene polymer. (For example, Patent Document 3).

  In addition, since 4-methyl-1-pentene polymer has high packaging properties, the adhesion with the heat seal layer is low, and between the heat seal layer and the layer containing 4-methyl-1-pentene polymer, Further, it is necessary to laminate and fix an adhesive layer such as maleic acid-modified resin. However, in order to impart heat sealability to the gas permeable film containing 4-methyl-1-pentene polymer as described above, when the heat seal layer or the adhesive layer is laminated, the gas permeation is caused by the heat seal layer or the adhesive layer. There was a problem that the performance decreased. In addition, in food packaging containing vegetable oil and the like, since the food locally generates heat, the packaging material is required to have a heat resistance of about 200 ° C., but polyethylene or polypropylene having a low melting point has the required heat resistance. There was a problem that it could not be obtained.

Japanese Patent Laid-Open No. 11-301691 Japanese Patent Laid-Open No. 2000-301474 JP 2001-189051 A

  This invention is made | formed in view of the trouble which the prior art has, and the place made into the subject is providing the film for packaging which has heat-sealability while having high gas permeability.

The first of the present invention relates to a packaging film.
[1] A film comprising 4-methyl-1-pentene (co) polymer (A) and a thermoplastic elastomer (B), wherein the content of (B) is (A) and (B) total 1-40 are parts by weight per 100 parts by weight, and the film a differential scanning calorimeter (DSC) is the (B) the origin to the melting point TmB2 is 100 ° C. or less and the melting point TmB2 measured by the on real Packaging film that is not observed.
[2] A film containing 4-methyl-1-pentene (co) polymer (A) and a thermoplastic elastomer (B), wherein the content of (B) is (A) and (B) total 1 to 40 parts by weight per 100 parts by weight, and the (B) of the differential scanning calorimeter (DSC) melting point TmB1 is 100 ° C. or less and the melting point TmB1 measured by is not substantially observed packaging Film.
[3] The packaging film according to [1] or [2], wherein the thermoplastic elastomer (B) is composed of at least one of an olefin elastomer and a styrene elastomer.
[4] Further, it contains a propylene (co) polymer (C), and the melting point TmC2 derived from (C) measured by a differential scanning calorimeter (DSC) of the film is in the range of 110 to 175 ° C. The packaging film according to any one of [1] to [3].
[5] A propylene (co) polymer (C) is further included, and (C) is 0.3 to 30 parts by mass with respect to a total of 100 parts by mass of (A), (B), and (C). The packaging film according to any one of [1] to [4].
[6] The packaging film according to any one of [1] to [5], wherein the density of the thermoplastic elastomer (B) is 850 to 980 kg / m ³ .
[7] A TEM image of a cut surface perpendicular to the main surface of the film (the distance in the film thickness direction of the imaging range is 15 μm and the imaging area is 45 μm ² ), and a 4-methyl-1-pentene (co) polymer ( The phase dispersion structure of a phase substantially composed of A) and a phase substantially composed of the thermoplastic elastomer (B) is observed, according to any one of [1] to [6] Packaging film.

The second of the present invention relates to a laminated packaging film.
[8] A laminated packaging film comprising the packaging film according to any one of [1] to [7] on a part or all of the outermost surface of at least one main surface.

The third of the present invention relates to a method for producing a packaging film.
[9] A 4-methyl-1-pentene (co) polymer (A) and a thermoplastic elastomer having a melting point TmB1 obtained by a differential scanning calorimeter (DSC) of 100 ° C. or lower, or the melting point TmB1 substantially not observed ( B), and the step of forming a melt-kneaded product having a content of (B) of 1 to 40 parts by mass with respect to a total of 100 parts by mass of (A) and (B) [1] Thru | or the manufacturing method of the film for packaging as described in any one of [7].

The fourth of the present invention relates to a packaging method using the packaging film of the present invention.
[10] A first step of covering a package to be packaged that absorbs or consumes oxygen and generates carbon dioxide with the packaging film according to any one of [1] to [8], and the packaging films And a second step of heat-sealing.

It is a cross-sectional TEM photograph parallel to MD direction of the base material layer of the packaging film which concerns on one Embodiment of this invention. It is a cross-sectional TEM photograph parallel to the TD direction of the base material layer of the packaging film which concerns on one Embodiment of this invention.

1. Packaging Film The packaging film of the present invention is a film containing 4-methyl-1-pentene (co) polymer (A) and a thermoplastic elastomer (B), the content of (B) mp TmB2 is 100 but the sum from 1 to 40 parts by weight per 100 parts by weight of (a) and (B), and derived from the measured by differential scanning calorimetry (DSC) (B) for the film It is a packaging film in which the melting point TmB2 is not substantially observed or below.

Or it is a film containing 4-methyl-1-pentene (co) polymer (A) and a thermoplastic elastomer (B), wherein the content of (B) is (A) and (B) For packaging in which the melting point TmB1 measured by the differential scanning calorimeter (DSC) of (B) is 100 ° C. or less or the melting point TmB1 is not substantially observed, with respect to 100 parts by weight in total. It is a film.

(1) 4-methyl-1-pentene (co) polymer (A)
The 4-methyl-1-pentene (co) polymer (A) is not particularly limited as long as it has a repeating unit derived from 4-methyl-1-pentene. That is, the 4-methyl-1-pentene (co) polymer is a homopolymer of 4-methyl-1-pentene, and 4-methyl-1-pentene other than 4-methyl-1-pentene. It may be a copolymer with a copolymerizable monomer. The “(co) polymer” in the present specification, such as propylene (co) polymer (C) described later, is a homopolymer as in the case of 4-methyl-1-pentene (co) polymer (A). And a copolymer are also included. Specifically, the monomer copolymerizable with 4-methyl-1-pentene is an olefin having 2 to 20 carbon atoms other than 4-methyl-1-pentene (hereinafter referred to as “olefin having 2 to 20 carbon atoms”). ").

  Examples of olefins having 2 to 20 carbon atoms to be copolymerized with 4-methyl-1-pentene include ethylene, propylene, 1-butene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1 -Tetradecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-eicosene, and the like are included, and olefins having 10 to 18 carbon atoms are preferable from the viewpoint of imparting appropriate flexibility to the film.

  The olefin having 2 to 20 carbon atoms copolymerized with 4-methyl-1-pentene may be one kind or a combination of two or more kinds. In the 4-methyl-1-pentene (co) polymer, the proportion of the structural unit derived from 4-methyl-1-pentene is usually 85 mol% or more, and from the viewpoint of improving gas permeability described later. 90 mol% or more is preferable. The proportion of structural units derived from olefins having 2 to 20 carbon atoms other than 4-methyl-1-pentene is preferably 15 mol% or less and 10 mol% or less. When the proportion of the structural unit derived from 4-methyl-1-pentene is less than 85 mol%, the density of the film increases and the gas permeability of a gas component having a large molecular weight decreases.

  The 4-methyl-1-pentene (co) polymer (A) is preferably a highly crystalline polymer from the viewpoint of making it difficult to break as a packaging film. The crystalline polymer may be either a polymer having an isotactic structure or a polymer having a syndiotactic structure, and is particularly preferably a polymer having an isotactic structure. It is easy to obtain. Further, the stereoregularity is not particularly limited as long as the 4-methyl-1-pentene polymer has a strength that can be formed into a film and can be used as a packaging film.

The density measured according to ASTM DM 1505 of the 4-methyl-1-pentene polymer (A) of the present invention is preferably 825 to 840 (kg / m ³ ), and is preferably 830 to 835 (kg / m). ³ ) is more preferable. When the density is smaller than the above range, the mechanical strength of the film is lowered, and there is a possibility that problems such as easy tearing may occur when used for packaging. On the other hand, if the density is larger than the above range, the gas permeability tends to decrease.

   The melt flow rate (MFR) of the 4-methyl-1-pentene (co) polymer (A) measured at 260 ° C. and a load of 2.16 kg in accordance with ASTM D1238 is a thermoplastic elastomer (B ) And within the extruder and is not particularly defined as long as it can be co-extruded, but is 0.5 to 50 g / 10 min, more preferably 1 to 30 g / 10 min. If MFR is in the above range, it is easy to extrude to a relatively uniform film thickness.

  The 4-methyl-1-pentene (co) polymer (A) may be produced directly by polymerizing olefins, or produced by thermally decomposing a high molecular weight 4-methyl-1-pentene polymer. May be. Further, the 4-methyl-1-pentene polymer may be purified by a method such as solvent fractionation that is fractionated based on a difference in solubility in a solvent, or molecular distillation that is fractionated based on a difference in boiling point.

  When the 4-methyl-1-pentene (co) polymer is directly produced by a polymerization reaction, for example, the amount of 4-methyl-1-pentene and an olefin having 2 to 20 carbon atoms, the kind of polymerization catalyst, the polymerization The melting point, stereoregularity, molecular weight and the like are controlled by adjusting the temperature, the amount of hydrogenation during polymerization, and the like. The method for producing the 4-methyl-1-pentene polymer by a polymerization reaction may be a known method. For example, it can be produced by a method using a known catalyst such as a Ziegler-Natta catalyst or a metallocene catalyst, preferably using a metallocene catalyst. On the other hand, when the 4-methyl-1-pentene polymer is produced by thermally decomposing a higher molecular weight 4-methyl-1-pentene polymer, the temperature and time of the pyrolysis are controlled. To the desired molecular weight. The 4-methyl-1-pentene (co) polymer (A) may be a commercially available polymer such as TPX manufactured by Mitsui Chemicals, Inc. in addition to the one produced as described above.

(2) Thermoplastic elastomer (B)
The thermoplastic elastomer (B) contained in the packaging film of the present invention is mixed with the packaging film of the present invention itself, that is, at least the 4-methyl-1-pentene (co) polymer (A) described above. The melting point TmB2 measured by a differential scanning calorimeter (DSC) is 100 ° C. or less or substantially no melting point TmB2 is observed, or the above (B) is measured by a scanning calorimeter (DSC). The melting point TmB1 is 100 ° C. or lower, or the melting point TmB1 is not substantially observed.

  By adjusting the melting point TmB1 or the melting point TmB2 to be lower than the temperature at the time of heat sealing described later, or by using a thermoplastic elastomer that does not have a melting point in the first place, that is, a low crystalline and thermoplastic elastomer, And forming an alloy structure (also referred to as phase dispersion structure) in which the thermoplastic elastomer (B) and the 4-methyl-1-pentene (co) polymer (A) are finely dispersed, without significantly impairing gas permeability, The toughness and heat sealability of the film can be improved.

  The melting point TmB1 of the thermoplastic elastomer (B) alone and the melting point TmB2 of the thermoplastic elastomer (B) in the packaging film are usually almost the same, but the aforementioned 4-methyl-1-pentene (co) polymer ( When the crystallinity of A) and other components described later is high, the melting point of the thermoplastic elastomer (B) itself may change due to the influence of these crystal components. Similarly, when the thermoplastic elastomer (B) having no melting point is used, the melting point TmB2 in the film may be observed. Usually, the difference between TmB1 and TmB2 is within 20 ° C. Further, by using a thermoplastic elastomer (B) having a melting point TmB1 of 100 ° C. or lower or a melting point TmB1 substantially not observed, a packaging film in which the melting point TmB2 is 100 ° C. or lower or substantially no melting point TmB2 is observed can be obtained. it can. The thermoplastic elastomer (B) is not particularly limited as long as it is a thermoplastic elastomer having the above-mentioned melting point, and specific examples include olefin-based elastomers and styrene-based elastomers.

  Specific examples of the olefin elastomer include a propylene / α-olefin copolymer, that is, a copolymer of propylene and an α-olefin other than propylene. The α-olefin in the propylene / α-olefin copolymer is preferably an α-olefin having 2 to 20 carbon atoms. Examples of the α-olefin having 2 to 20 carbon atoms include ethylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene and 1-decene, preferably Ethylene, 1-butene. The α-olefin contained in the propylene / α-olefin copolymer may be one type or a combination of two or more types. The propylene / α-olefin copolymer is more preferably a propylene / 1-butene / ethylene copolymer.

  The styrene elastomer is composed of polystyrene as a hard segment and polybutadiene, polyisoprene, a copolymer of polybutadiene and polyisoprene, or a hydrogenated product thereof as soft segments. Hydrogenation may be performed only on a part of polybutadiene or polyisoprene, or all may be hydrogenated. Such styrenic elastomers can be imparted with good adhesion by being modified with functional groups such as carboxylic acid groups, acid anhydride groups, amino groups, epoxy groups and hydroxyl groups. Commercially available modified styrene elastomers include “Tuftec” (manufactured by Asahi Kasei Chemicals, registered trademark), “Clayton” (manufactured by Kraton Polymer Japan, registered trademark), “Dynalon” (manufactured by JSR, registered trademark), “ Septon "(manufactured by Kuraray Co., Ltd., registered trademark)," SIBSTER "(manufactured by Kaneka Corporation, registered trademark), and the like.

  Olefin-based elastomers and styrene-based elastomers can be obtained by copolymerizing monomers (monomers) constituting the elastomer in the presence of a conventionally known production method, for example, a Ziegler-Natta catalyst or a metallocene-based catalyst. Specifically, the propylene / α-olefin copolymer can be obtained by copolymerizing propylene and an α-olefin other than propylene.

  1-50 MPa is preferable and, as for the tensile elasticity modulus in 23 degreeC measured based on JISK7113-2 of a thermoplastic elastomer (B), 3-45 MPa is more preferable. When the tensile elastic modulus is smaller than the above range, the handling property of the film is lowered. On the other hand, when the tensile elastic modulus is larger than the above range, there is a concern that the flexibility and toughness of the film of the present invention are lowered and the heat sealability is lowered.

Further preferably the density is measured in accordance with ASTM DM1505 of the thermoplastic elastomer (B) is a 850~980kg / m ^3, more preferably 860~970kg / m ^3.

  The melt flow rate (MFR) measured at 260 ° C. under a load of 2.16 kg in accordance with ASTM D1238 of the thermoplastic elastomer (B) is an extrusion with the 4-methyl-1-pentene (co) polymer (A). It is not particularly defined as long as it is easy to mix in the machine and can be co-extruded. As described later, in order to improve the handleability of the thermoplastic elastomer (B), a propylene (co) polymer (C) and a thermoplastic elastomer (B) are mixed to form a mixture, and then 4-methyl-1 -When the pentene (co) polymer (A) and the mixture are mixed in an extruder, the melt flow rate (MFR) of the mixture of the thermoplastic elastomer (B) and the propylene (co) polymer (C) is preferably It is 1-50 g / 10min, More preferably, it is 3-40 g / 10min. If MFR is in the above range, it is easy to extrude to a relatively uniform film thickness.

The content of the thermoplastic elastomer (B) contained in the packaging film of the present invention is 100 parts by mass in total of 4-methyl-1-pentene (co) polymer (A) and the thermoplastic elastomer (B). preferably 1 to 40 by mass parts, and more preferably 2 to 20 parts by weight. By including the 4-methyl-1-pentene (co) polymer (A) and the thermoplastic elastomer (B) at the above ratio, the component A and the component B are appropriately phase-dispersed as described later, for example, When the present invention is used as a packaging film, heat sealability can be imparted without greatly impairing gas permeability.

The packaging film of the present invention has a structure in which 4-methyl-1-pentene (co) polymer (A) and thermoplastic elastomer composition (B) having relatively high crystallinity are phase-separated and dispersed. It is preferable to have (phase dispersion structure). Specifically, a sea-island structure or a laminated structure is observed in a TEM image of a cut surface perpendicular to the main surface of the packaging film of the present invention (the distance in the film thickness direction of the imaging range is 15 μm and the imaging area is 45 μm ² ). The sea part is substantially composed of the 4-methyl-1-pentene copolymer (A), and the island part is substantially composed of the propylene-based elastomer composition (B). It is preferable to have. Note that “substantially constituted” means that a compound that is easily compatible with either component (A) or component (B) may be included. Specifically, since the component (C) described later is easily compatible with the component (B), in the packaging film of the present invention containing the component (C), the island portion is composed of the component (B) and the component (C). Becomes compatible.

  FIG. 1A is an example of a TEM image of a cross section parallel to the MD direction of the packaging film of the present invention, and FIG. 1B is an example of a TEM image of a cross section parallel to the TD direction of the packaging film of the present invention. As shown in FIGS. 1A and 1B, in the film cross-sectional TEM images in the MD direction and the TD direction, a bright portion extending in a direction parallel to the film surface, that is, a portion having a lower electron density than the dark portion is seen.

  Such a phase dispersion structure can be observed as a “light / dark structure” by a transmission electron microscope (TEM) image obtained by observing a cross section of the packaging film of the present invention in a thin slice. In the TEM image of FIG. 1A, for example, “bright part” is 4-methyl-1-pentene (co) polymer (A) having a relatively low electron density; “dark part” is heat having a relatively high electron density. 4-methyl-1-pentene (co) polymer having high compatibility with thermoplastic elastomer (B), such as propylene (co) polymer (C), which will be described later, is relatively high in plastic elastomer (B) or thermoplastic elastomer (B) It is considered to be a mixture of compounds having low compatibility with (A).

  The mechanism that the phase dispersion structure exerts on the effect of the present invention is not necessarily clear, but is presumed as follows. That is, when the gas comes into contact with the packaging film having the phase separation structure as described above, the sea part is a phase substantially consisting of a 4-methyl-1-pentene (co) polymer (A) which is bulky and has a low electron density. Gas permeates through (continuous phase). Further, the gas permeates through a fine gap at the interface between the phase substantially consisting of component A and the phase consisting essentially of component B. On the other hand, since the phase substantially consisting of the thermoplastic elastomer (B) having a lower gas permeability than the component A is distributed in the packaging film in the form of islands, the gas permeation in the film is not significantly inhibited. In addition, it is considered that heat sealability is expressed because the island portion substantially composed of the thermoplastic elastomer (B) in the vicinity of the film surface of the present invention is dissolved or softened by heating at the time of heat sealing described later and spreads on the film surface.

(3) Propylene (co) polymer (C)
The packaging film of the present invention may further contain a propylene (co) polymer (C). By including such a propylene (co) polymer (C), an effect of suppressing blocking at the time of kneading of raw materials or film forming, and an effect of improving film moldability can be expected.

  The propylene (co) polymer (C) is substantially a homopolymer of propylene, but may contain a small amount of α-olefin other than propylene, so-called homopolypropylene (hPP), random polypropylene (rPP) and Any of block polypropylene (bPP) may be used. The content of α-olefin other than propylene in polypropylene is preferably 20 mol% or less, more preferably 10 mol% or less.

  When the packaging film of the present invention contains the propylene (co) polymer (C), the film of the present invention itself, that is, at least the aforementioned 4-methyl-1-pentene (co) polymer (A) and thermoplasticity. It is preferable that melting | fusing point TmC2 measured by a differential scanning calorimeter (DSC) exists in 110 to 175 degreeC with respect to the thing in which the elastomer (B) and the component C are mixed, and 120 to 170 degreeC is more. preferable.

Substantially propylene (co) polymer Mika Ranaru propylene (co) polymer of (C) (C) a single melting point TMC1, the melting point TmC2 propylene packaging films in the (co) polymer (C) is Usually, the thermoplastic elastomer (B), which is almost the same but has a low melting point or substantially no melting point, and a 4-methyl-1-pentene (co) polymer (A) having a high melting point are kneaded. When a dispersion structure is formed, TmC2 may be higher or lower than TmC1, but the difference between TmC1 and TmC2 is usually within 20 ° C.

The content of the propylene (co) polymer (C) is preferably 0.3 to 30 parts by mass with respect to 100 parts by mass in total of the component A, the component B and the component (C), and 0.5 More preferably, it is -25 mass parts . When the content of the propylene (co) polymer (C) is less than 5 parts by mass , the thermoplastic elastomer (B) may be easily blocked. On the other hand, when it exceeds 20 mass parts , when the film of this invention is used for packaging, gas permeability and heat sealability may fall.

(4) Other components The packaging film of the present invention is preferably substantially composed of the above-mentioned component A and component B and / or component (C) in order to form the aforementioned phase separation structure. In the range which does not impair the purpose, other resins and additives may be included. Examples of the additive include a heat stabilizer, a weather stabilizer, a rust inhibitor, a copper damage stabilizer, and an antistatic agent. It is preferable that content of an additive shall be 0.0001-10 mass parts with respect to 100 mass parts of the whole resin composition which comprises the film of this invention.

(5) Laminate The packaging film of the present invention can also be used as a laminated film (also referred to as a laminated packaging film) laminated with another film. In order to make use of the gas permeability and heat sealability of the film of the present invention, the packaging film of the present invention is placed on the surface of at least one main surface of the laminated packaging film so as to be brought into contact with an object fixed by heat sealing. It is preferable to use it on a part of or the entire surface of the layer (also called the outermost layer). Moreover, you may form the thin skin layer mentioned later in the grade which does not inhibit gas permeability to the surface layer of the said film further. Moreover, in order to adjust mechanical strength and heat resistance, you may provide the base material layer which is not made to contact with a molding material.

(Skin layer)
The skin layer may be formed by uneven distribution of components in the film formed during the production of the film of the present invention described later, or may be formed by a coextrusion method. In addition, after manufacturing the packaging film, it may be formed by laminating another film, or may be formed by applying and drying a liquid material by a coating method or the like, although not particularly limited. The skin layer is preferably formed of a material having gas permeability and heat sealability. Specifically, the content of the aforementioned 4-methyl-1-pentene (co) polymer (A) or component A is included. An example is a resin having a large amount of.

  The skin layer preferably has a tensile modulus or thickness that does not impair gas permeability, and specifically has a thickness of about 1 to 10 μm. The laminated packaging film may have an intermediate layer. At least one main surface of the intermediate layer is provided with the packaging film of the present invention, and the intermediate layer is preferably used so as not to contact the molding material during heat sealing.

(Base material layer)
The base material layer is used for adjusting the mechanical strength of the laminated packaging film of the present invention. Specifically, propylene (co) polymer, 4-methyl-1-pentene (co) polymer, 4-methyl-1-pentene (co) polymer (A) and thermoplastic elastomer (B) and / or A mixture of propylene (co) polymer (C), wherein the content of (B) is less than 10 parts by mass with respect to a total of 100 parts by mass of (A) and (B), polyethylene terephthalate or poly Examples include polyesters such as butylene terephthalate, polyamides, polyacetals, polycarbonates, and mixtures thereof. By laminating with a base material layer formed of these materials, it is possible to obtain a packaging film more suitable for packaging such as being hard to tear.

  The thickness of a base material layer is 5-40 micrometers normally, Preferably it is 5-25 micrometers, More preferably, it is 10-25 micrometers. When the thickness of the base material layer is within the above range, the tear resistance is exhibited. Further, by setting the thickness of the base material layer within the above range, the gas permeability is not greatly impaired.

(Adhesive layer)
An adhesive layer may be disposed between the base material layer and the surface layer. By disposing the adhesive layer, the adhesion between the base material layer and the surface layer can be made more reliable, and defects such as peeling during use can be effectively suppressed.

  The adhesive layer can be formed of an adhesive resin. Specific examples of the adhesive resin include a modified 4-methyl-1-pentene-based polymer graft-modified with at least a part of unsaturated carboxylic acid and / or an acid anhydride of unsaturated carboxylic acid; Examples thereof include a mixture containing a 1-pentene polymer and an α-olefin polymer; a polyolefin elastomer and the like. The thickness of the adhesive layer is preferably a thickness that does not inhibit gas permeation, and is specifically about 4 to 6 μm.

   As the layer structure of the laminated packaging film of the present invention, the surface layer is “A”, the base material layer is “B”, the adhesive layer is “C”, and the skin layer is “S”. Structure), A / B (two-layer structure), A / B / A (three-layer structure), A / C / B (three-layer structure), S / A / B (three-layer structure), S / A / B / A / S (5-layer structure). In addition, the packaging film of the present invention which is not a laminate is expressed as A (single layer structure) in the above description.

  Although the preferable thickness of the film for packaging of this invention is not specifically limited, It is preferable that it is 10-300 micrometers, and it is still more preferable that it is 50-200 micrometers. When the thickness of the packaging film is less than 10 μm, the handleability may be deteriorated or the film may be broken at the time of peeling. On the other hand, if it exceeds 300 μm, the easy peel property may deteriorate. Similarly, in the case of a laminated packaging film using the packaging film of the present invention, the thickness of the entire laminate is preferably 10 to 300 μm, and more preferably 50 to 200 μm.

  60-500 MPa is preferable and, as for the tensile elasticity modulus in 23 degreeC measured based on JISK7127 of the packaging film of this invention, 70-400 MPa is more preferable. If the tensile modulus is too small, the handling property of the packaging film of the present invention is lowered, and the film is easily deformed. If the tensile elastic modulus is larger than the above range, the easy peel property may be impaired.

2. Method for Producing Packaging Film The packaging film of the present invention can be produced by any method, but has a melting point TmB1 obtained by 4-methyl-1-pentene copolymer (A) and a differential scanning calorimeter (DSC). And a thermoplastic elastomer (B) in which the melting point TmB1 is not substantially observed, and the content of (B) is 1 to 100 parts by mass with respect to a total of 100 parts by mass of (A) and (B). It is preferable to manufacture by the manufacturing method including the process of shape | molding 40 mass parts melt-kneaded material.

  A specific method for forming a film is, for example, 1) Melting and kneading pellets of 4-methyl-1-pentene (co) polymer (A) and pellets of thermoplastic elastomer (B) with an extruder, and extrusion. Method of forming a packaging film by molding (dry blend method); 2) Melting and kneading 4-methyl-1-pentene (co) polymer (A) and thermoplastic elastomer (B) with a twin screw extruder or the like The melt blend resin pelletized in this way is melt-kneaded again in an extruder and extruded to produce a packaging film (melt blend method); 3) 4-methyl-1-pentene (co) polymer ( For example, there is a method (press film method) in which a melt blend resin obtained by melting and kneading A) and a thermoplastic elastomer (B) with an extruder or the like and pelletizing is pressed to a predetermined thickness with a press.

    When a packaging film is produced by the extrusion molding of 1) and 2), the extrusion temperature is obtained by uniformly kneading the 4-methyl-1-pentene (co) polymer (A) and the thermoplastic elastomer (B). Any temperature can be used as long as it can be molded to a uniform thickness, for example, about 230 to 290 ° C. Extrusion molding can be performed by a known extruder having, for example, a T die or an inflation die.

  In the case of producing a packaging film by press molding of the above 3), the pressing condition is that the 4-methyl-1-pentene (co) polymer (A) and the thermoplastic elastomer (B) are melted to have a uniform thickness. What is necessary is just to set to the conditions which can be shape | molded on a sheet | seat. The press temperature can be set to, for example, about 230 to 290 ° C. Press molding can be performed with a known press.

  When the above-mentioned propylene (co) polymer (C) is added, the propylene (co) polymer is separated from the 4-methyl-1-pentene (co) polymer (A) and the thermoplastic elastomer (B). (C) may be added, but after the thermoplastic elastomer (B) and the propylene (co) polymer (C) are previously kneaded to prepare a mixture (hereinafter also referred to as composition (D)), 4- In some cases, it is easier to produce a packaging film when kneaded with the methyl-1-pentene (co) polymer (A). This is because it is difficult to handle the thermoplastic elastomer (B) that is sticky even near room temperature alone, and when it is molded into a pellet and stored, the pellets may stick together, whereas propylene having a high melting point ( This is because the co-polymer (C) and the component B are mixed in advance to prepare the composition (D), whereby the tackiness can be reduced and the handling property can be improved. Moreover, after preparing the composition (D) which is a component which becomes an island part of the said phase dispersion structure previously, it mixes with the 4-methyl-1-pentene (co) polymer (A) used as the sea part of the said phase dispersion structure. Thus, it is considered that a phase dispersion structure can be easily formed by manufacturing a film.

  As described above, the packaging film of the present invention has excellent gas permeability and heat sealability. For this reason, the film of the present invention can be used for the packaging of various objects, but is particularly suitable for an MA package that wraps a substance that reacts with oxygen gas to generate carbon dioxide gas, specifically, fruits and vegetables. . When the permeability of oxygen gas such as fruits is too high, the respiratory action is actively performed, and taste components and nutrients such as sugar and acid are consumed, and the freshness is drastically lowered. On the other hand, if the gas permeability is too low, the respiratory action is suppressed, fermentation starts, aldehyde and ethanol are generated, and a bad odor is likely to be generated. Therefore, the film of the present invention is suitably used as an MA packaging film having appropriate gas permeability and gas selectivity in order to achieve a gas composition suitable for maintaining the freshness that changes depending on the type and ripeness of fruits and vegetables. be able to.

3. Packaging Method Using Packaging Film The packaging film of the present invention is suitably used as a packaging film for the aforementioned fruits and vegetables. The packaging method of the present invention includes a first step of covering a packaged body that absorbs or consumes oxygen such as fruits and vegetables and generates carbon dioxide with the packaging film of the present invention, and second heat-seals the packaging films. These steps are included.

  In the first step, a packaged body that absorbs or consumes oxygen such as fruits and vegetables and generates carbon dioxide is placed on the packaging film of the present invention, and the packaged body is wrapped with the packaging film, or for packaging Fold the film to cover it. The method for wrapping may be a commonly used method and is not particularly limited, but may be performed manually or using an existing packaging apparatus.

   In the second step, heat sealing is performed by heating the overlapped portion of the packaging film covering the package in the first step. The heat sealing method is performed by a commonly used method, and is not particularly limited, but is performed by an impulse sealer or the like. Moreover, when heat-sealing, after heating the overlapping part of the said film for packaging to the temperature more than melting | fusing point of a component (B), it cools. As a result, the component (B) is mainly dissolved and fused, so that the overlapping portion is fixed and sealed.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited at all by this.

(1) 4-methyl-1-pentene copolymer (A)
As 4-methyl-1-pentene copolymer (A) contained in the expandable substrate film, 4-methyl-1-pentene copolymer (A1) shown in Table 1 (trade names: TPX DX310, Mitsui Chemicals ( Co., Ltd.), 4-methyl-1-pentene copolymer (A2) (trade name TPX MX002, manufactured by Mitsui Chemicals), 4-methyl-1-pentene copolymer (A3) (trade name TPX MX004) 4-methyl-1-pentene copolymer (A4) (trade name TPX RT31, manufactured by Mitsui Chemicals), 4-methyl-1-pentene copolymer (A5) (manufactured by Mitsui Chemicals, Inc.) Trade name TPX DX845, manufactured by Mitsui Chemicals, Inc.) was used. Furthermore, 1) tensile elastic modulus (room temperature) 2) MFR of 4-methyl-1-pentene copolymers (A1) to (A5) were measured as follows. The results are shown in Table 1.
1) Tensile modulus (room temperature)
Based on ASTM-0638, the elastic modulus was measured about the injection-molded body.
2) Measurement of MFR Measurement was performed under conditions of a temperature of 240 ° C. or 260 ° C. and a load of 2.16 kg in accordance with ASTM D1238.
3) Measurement of melting point It was determined from the peak temperature according to JIS K7121.

(2) Thermoplastic elastomer (B)
(Synthesis Example 1)
After charging 833 ml of dry hexane, 100 g of 1-butene, and 1.0 mmol of triisobutylaluminum in a 2000 ml polymerization apparatus sufficiently purged with nitrogen, the temperature in the polymerization apparatus was raised to 40 ° C. The pressure in the system was increased to 0.76 MPa with propylene. Next, the pressure in the polymerization apparatus was adjusted to 0.8 MPa with ethylene. Next, 0.001 mmol of dimethylmethylene (3-tert-butyl-5-methylcyclopentadienyl) fluorenylzirconium dichloride was brought into contact with 0.3 mmol of methylaluminoxane (made by Tosoh Finechem) in terms of aluminum. The toluene solution was added to the polymerization apparatus, polymerized for 20 minutes while maintaining the internal pressure at 0.8 MPa with ethylene at an internal temperature of 40 ° C., and then 20 ml of methanol was added to stop the polymerization reaction. After depressurization, the polymer was precipitated from the polymerization solution in 2 L of methanol and dried under vacuum at 130 ° C. for 12 hours to obtain 36.4 g of a thermoplastic elastomer (B1).

(Synthesis Example 2)
A thermoplastic elastomer (B2) was obtained in the same manner as in Synthesis Example 1 except that the copolymerization ratio of propylene, ethylene and 1-butene was changed as shown in Table 2.
The compositions of the thermoplastic elastomers (B1) to (B2) obtained in Synthesis Examples 1 and 2 are summarized in the table. The results are shown in Table 2. In addition, mol% in a table | surface is mol% when the sum total of the propylene in a thermoplastic elastomer (B), ethylene, and 1-butene is 100 mol%.

(3) Synthesis of Composition (D) Composition (D), which is a mixture of thermoplastic elastomer (B) and propylene (co) polymer (C), was synthesized as follows.
(Synthesis Example 3)
90 parts by mass of the thermoplastic elastomer (B1) obtained in Synthesis Example 1 and 10 parts by mass of homopolypropylene (C1) as a propylene (co) polymer (C) (F107BV made of prime polymer, melting point = 160 ° C., 260 MFR at 14 ° C. = 14 g / 10 min) was kneaded at 200 ° C. with a twin screw extruder to obtain a composition (D1).

(Synthesis Example 4)
85 parts by mass of the thermoplastic elastomer (B2) obtained in Synthesis Example 2 and 15 parts by mass of homopolypropylene (C1) as a propylene (co) polymer (C) (F107BV made of prime polymer, melting point = 160 ° C., 260 A composition (D2) was obtained in the same manner as in Synthesis Example 4 except that the MFR at 14 ° C. was kneaded. MFR of the obtained compositions (D1) to (D2) was measured in the same manner as described above. 4) Tensile modulus (room temperature) and 5) Density was measured as below, and melting point was measured in the same manner as 3) melting point. The results are shown in Table 3.

4) Tensile modulus (room temperature)
In accordance with JIS K7113-2, the test temperature was room temperature (23 ° C.), the test speed was 200 mm / min, and the elastic modulus in the MD direction of the film was measured. Tensile modulus, the S-S curve was calculated from the tangent slope of S-S curve starting from the elongation amount zero.
5) Density The density was measured according to ASTM D1505.

(Synthesis Example 5)
96 parts by mass of 4-methyl-1-pentene copolymer (A1) and 4 parts by mass of the composition (D2) obtained in Synthesis Example 4 were kneaded at 260 ° C. in a twin screw extruder, and the mixture ( E1) was obtained.

(Synthesis Examples 6-15)
In Synthesis Example 5, except that 4-methyl-1-pentene copolymer (A), composition (D), and propylene (co) polymer (C) were kneaded at the ratios shown in Tables 4 and 5. In the same manner as in Synthesis Example 5, mixtures (E2) to (E10) were obtained. MFR of the obtained mixtures (E1) to (E10) was measured in the same manner as described above. The results are shown in Table 4.

(Example 1)
The mixture E1 as a raw material for the packaging film was put into an extruder equipped with a full flight type screw, melted and kneaded, the extrusion temperature was set to 260 ° C., and the molten resin was extruded by a single layer T die.

(Examples 2-6 and 8-10 , Comparative Examples 1-2 , Reference Example)
A packaging film was obtained in the same manner as in Example 1 except that the mixture E1 was changed to a raw material as shown in Tables 5 and 6 as a raw material for the packaging film. For Comparative Examples 1 and 2, films were prepared using only the component (A).

(Comparative Example 3)
The 4-methyl-1-pentene copolymer (A1) and the composition (D2) were charged into extruders equipped with different full-flight screws, and melt-kneaded in the different extruders. Next, the extrusion temperature was set to 230 ° C., and two layers of molten resin (A1) and (D2) were laminated in a multilayer die and co-extruded to obtain a film having a two-layer structure.

  The films obtained in Examples and Comparative Examples were evaluated for 4) tensile elastic modulus (room temperature) as described above, and 6) gas permeability and 7) heat sealability were evaluated as follows. These results are shown in Tables 5 and 6. Further, 8) TEM observation was performed as follows for some examples of films. These results are shown in FIGS. 1A and 1B.

6) Measurement of gas permeability It evaluated based on JISK7126-1 (pressure sensor method). Specifically, using a differential pressure method gas permeability measuring apparatus (manufactured by Toyo Seiki Seisakusho), the film measurement area was 5 cm ² at a test temperature of 23 ° C. and a test humidity of 0% RH. As for the film measurement area, two aluminum masks with adhesive material made by Modern Kotrol Co., Ltd. (Mocon) with a hole of 25 mm in diameter in the center are prepared, and the film to be measured is sandwiched between the two masks. It was laminated and adjusted. The central hole is arranged so that it overlaps with two masks.

7) Evaluation of heat sealability Each of the two packaging films of the present invention was folded in two, and sandwiched between 100 μm thick Teflon (registered trademark) films to prevent contamination, was used as a test piece. Next, using a heat seal tester (manufactured by Tester Sangyo Co., Ltd., thermal gradient heat seal tester TP-701-G), the test piece was subjected to an upper temperature of 220 ° C, a lower temperature of 70 ° C, a seal width of 10 mm, and a seal pressure Of 0.2 MPa and a sealing time of 1 second (also referred to as heat sealing). Next, taking out the packaging film of the present invention heat-sealed from the test piece, the heat-sealed sample with a width of 15 mm, using a seal strength tester (Nidec Lampo Co., Ltd. force gauge FPG), Tensile speed 100 mm / min. The film was peeled (also called peel) at a tensile speed of 1, and the maximum strength was defined as heat seal strength. Moreover, when the toughness (toughness) of the film is low, the film is broken or cracked at the time of peeling. When there was no breakage at the time of peeling and the sealed film was peeled off, the easy peelability (also referred to as easy peel property) was evaluated as “◯”. The heat sealability referred to in the present invention means that it has a certain heat seal strength and also has an easy peel property.

8) TEM observation A sample piece of the film of Example 3 having a thickness of 100 μm was prepared. Cross sections obtained by cutting this sample piece in the MD direction parallel to the TD direction and the TD direction parallel to each other at a magnification of 10,000 using a transmission electron microscope (TEM, H-7650 manufactured by Hitachi, Ltd.). Each was observed. 1A is a cross-sectional TEM photograph parallel to the MD direction of the film of Example 3, and FIG. 1B is a cross-sectional TEM photograph parallel to the TD direction of the film.

As shown in Table 5, the films of Examples 1 to 6 , 8 to 10 , and the reference example have a certain gas permeability and excellent heat sealability as compared with the films of Comparative Examples 1 to 3. I understand. In particular, when Comparative Examples 1 to 3 which are films made of 4-methyl-1-pentene (co) polymer (A) are compared with Examples, the films of Examples have high sealing strength and easy peelability. In addition, since it has extremely excellent heat sealability, it can be seen that it is excellent as a packaging film. When Examples 1-4 are compared, it turns out that a gas-permeation coefficient falls, so that a component (A) reduces. From this, in the film of this invention, it turns out that gas permeability can be adjusted by adjusting the addition amount of a component (A) according to the decay property etc. of the thing to package. Moreover, it can be seen from the cross-sectional TEM photographs of FIGS. 1A and 1B that the film of Example 3 has a phase dispersion structure. In addition, the light part (relatively light gray part) of the TEM photograph is a phase substantially composed of 4-methyl-1-pentene (co) polymer (A), and the dark part (relatively dark black part) is It is considered that the phase is substantially composed of the thermoplastic elastomer (B) and the propylene (co) polymer (C).

  Since the packaging film of the present invention has a certain gas permeability and is excellent in heat sealability, it can be widely used as a packaging film. In particular, the film of the present invention is preferably used for MA packaging because of the difference in carbon dioxide gas and oxygen gas permeability.

Claims (9)

A film comprising 4-methyl-1-pentene (co) polymer (A), a thermoplastic elastomer (B), and a propylene (co) polymer (C) ,
Wherein (B) 1 to 40 parts by weight per 100 parts by weight of the content (A) and the (B) and the,
The content of (C) is 0.6 to 11 parts by mass with respect to 100 parts by mass in total of (A), (B) and (C),
And the melting | fusing point TmB2 derived from the said (B) measured with a differential scanning calorimeter (DSC) about the said film is 100 degrees C or less, or the film for packaging in which the said melting | fusing point TmB2 is not observed substantially. A film comprising 4-methyl-1-pentene (co) polymer (A), a thermoplastic elastomer (B), and a propylene (co) polymer (C) ,
Wherein (B) 1 to 40 parts by weight per 100 parts by weight of the content (A) and the (B) and the,
The content of (C) is 0.6 to 11 parts by mass with respect to 100 parts by mass in total of (A), (B) and (C),
And the melting | fusing point TmB1 measured by the differential scanning calorimeter (DSC) of the said (B) is 100 degrees C or less, or the film for packaging in which the said melting | fusing point TmB1 is not observed substantially. The packaging film according to claim 1, wherein the thermoplastic elastomer (B) comprises one or more of an olefin elastomer and a styrene elastomer. Before SL film melting TmC2 derived from said measured by differential scanning calorimetry (DSC) (C) for is in the range of one hundred ten to one hundred and seventy-five ° C., packaging according to any one of claims 1 to 3 the film. The packaging film according to any one of claims 1 to 4 , wherein the density of the thermoplastic elastomer (B) is 850 to 980 kg / m ³ . TEM images main surface of the vertical cutting plane of the film (the imaging range of the film thickness direction of the distance 15μm and imaging area 45 [mu] m ^2,) at the 4-methyl-1-pentene (co) polymer (A) A packaging film according to any one of claims 1 to 5 , wherein a phase-dispersed structure consisting of a phase substantially composed of the above and a phase substantially composed of the thermoplastic elastomer (B) is observed. . A laminated packaging film comprising the packaging film according to any one of claims 1 to 6 on a part or all of the outermost surface of at least one main surface. The 4-methyl-1-pentene (co) polymer and (A), differential scanning calorimetry (DSC) the thermoplastic elastomer having a melting point TmB1 is 100 ° C. or less and the melting point TmB1 is not substantially observed obtained in (B a) comprises at said propylene (co) polymer (C), wherein (1 to 40 parts by weight per 100 parts by weight of the content of B) is the the (a) (B) There is formed a melt-kneaded product having a content of (C) of 0.6 to 11 parts by mass with respect to a total of 100 parts by mass of (A), (B) and (C). The manufacturing method of the film for packaging as described in any one of Claims 1 thru | or 6 including a process. A first step of covering a package that absorbs or consumes oxygen and generates carbon dioxide with the packaging film according to any one of claims 1 to 6 , and a second step of heat-sealing the packaging films together. A packaging method comprising the steps of: