JP5615623B2 - Heat sealing film and packaging bag - Google Patents

Description

  The present invention relates to a heat sealing film and a packaging bag.

  In general, an ethylene-vinyl alcohol copolymer (hereinafter also referred to as “EVOH”) is excellent in transparency, gas barrier properties, aroma retention, solvent resistance, oil resistance, heat sealability, and the like. It is used for heat sealing films as food packaging materials, industrial chemical packaging materials, agricultural chemical packaging materials, pharmaceutical packaging materials, and the like. Such a heat sealing film is molded into a packaging bag or other container such as a bottle. Among the various properties of EVOH, in particular, the use of fragrance retention, in other words, non-sorption of fragrance components, foods, beverages, luxury products, pharmaceuticals, cosmetics, fragrances, toiletry products, etc. containing fragrance components and medicinal components Of these packaging bags, those having a resin layer containing EVOH as the innermost layer are widely used.

  As a technique related to a packaging container provided with such a resin layer containing EVOH, for example, a paper container using EVOH as a back surface (innermost) layer and a polyolefin resin as a surface layer (Japanese Patent Laid-Open No. 1-218823) Gas barrier multilayer container using two types of EVOH satisfying specific conditions as innermost layers (see JP-A-3-112654, JP-A-3-112655, etc.), and having a specific storage elastic modulus A container having a layer made of EVOH in the innermost layer (see JP 2001-192011 A) has been proposed.

  However, there is a high demand for perfume retention during storage of foods, fragrances, luxury products, etc., and any of the above-mentioned containers having a layer containing EVOH is sufficiently satisfied with the perfume retention. It cannot be said that there is room for improvement.

JP-A-1-218823 JP-A-3-112654 JP-A-3-112655 Japanese Patent Laid-Open No. 2001-192011

  The present invention has been made in view of these disadvantages, and provides a heat-sealing film having excellent non-sorption to scent components, and a packaging bag with high aroma retention formed from this film. Objective.

The invention made to solve the above problems is
The outermost layer includes a heat-sealing layer containing an ethylene-vinyl alcohol copolymer,
The ethylene content of the ethylene-vinyl alcohol copolymer is 20 mol% or more and 70 mol% or less, the saponification degree is 90 mol% or more,
The heat-sealing film has an equilibrium moisture content of 0.5% by mass or more and 5.0% by mass or less at a temperature of 23 ° C. and a relative humidity of 50%.

  The film for heat sealing is provided with a heat-sealing layer containing EVOH having an ethylene content and a saponification degree in the above range as an outermost layer, and the heat-sealing layer has an equilibrium moisture content in the above-mentioned range. It can exhibit excellent non-sorption properties for ingredients. In particular, in the heat sealing film, since the heat-sealing layer has an equilibrium moisture content in the above range, the heat-sealing layer can contain a certain amount of water, and as a result, the heat-sealing layer. It is possible to adopt a structure in which water molecules are arranged in the gaps between the EVOH molecular chains. Therefore, according to the heat sealing film, the adsorption of the scent component can be effectively suppressed by reducing the voids in the heat fusion layer with water molecules. In particular, the surface of the heat-sealing layer, which has increased polarity due to the arrangement of water molecules, extremely effectively suppresses the sorption of low-polar scent components such as hydrocarbon compounds. Can be demonstrated. The heat sealing film may be a multilayer or a single layer as long as the heat-sealing layer is at least one outermost layer.

  The heat-sealing film preferably has a layer structure of two or more layers, and at least one outermost layer is preferably composed of the heat-sealing layer. By making the film for heat sealing into such a multilayer structure, mechanical properties can be improved or various functions can be imparted.

  The moisture content of the heat sealing layer is preferably 0.1% by mass or more and 4.0% by mass or less. By setting the moisture content within the above range, foaming of the film due to vaporization of moisture in the heat-sealing layer during heat sealing can be prevented, heat sealing properties can be improved, and appearance defects can be prevented.

  In the differential scanning calorimetry in which the thermal fusion layer was measured from 30 ° C. to 300 ° C. at a heating rate of 10 ° C./min, the half-value width of the endothermic peak indicating the melting of the EVOH was 5.0 ° C. or higher and 20.0 It is good that it is below ℃. According to the heat sealing film, by using EVOH having a specific width in the melting temperature as described above, it is possible to increase the sealing strength by heat sealing at a low temperature and to suppress the thinning at the time of heat sealing. .

The solubility parameter (SP value) of the ethylene-vinyl alcohol copolymer is 11.0 or more, the melting point is 170 ° C. or less, the density of the heat sealing layer is 1.10 g / cm ³ or more, and the thickness is 2 μm or more. It is good in it being 100 micrometers or less. According to the heat sealing film, the non-sorption property is further increased by using EVOH having a solubility parameter of 11.0 or more and the density of the heat-fusible layer being 1.10 g / cm ³ or more. be able to. Moreover, the heat-sealing film can further improve heat-sealability by using EVOH having a melting point of 170 ° C. or lower. Furthermore, according to the film for heat sealing, by making the thickness of the heat-fusible layer in the above range, it is possible to achieve both the non-sorption property and the heat sealing property at a high level.

The ethylene-vinyl alcohol copolymer has a terminal carboxylic acid unit and a lactone ring unit,
The total amount of the terminal carboxylic acid unit and the lactone ring unit relative to the total amount of the ethylene unit, the vinyl alcohol unit, and the vinyl ester unit may be 0.05 mol% or more and 0.30 mol% or less. When the terminal of EVOH has a specific amount of carboxylic acid unit and lactone ring unit, the heat seal strength during heat sealing at a low temperature can be further increased.

  The heat fusion layer contains a metal salt, and the content of the metal salt in the heat fusion layer is preferably 1 ppm or more and 10,000 ppm or less in terms of metal element. According to the heat sealing film, by including a metal salt in the heat-sealing layer, the polarity is further increased, and the non-sorption property of the low-polar scent component can be further increased.

  The said heat sealing | fusion layer contains a boron compound, and it is good in content of this boron compound being 50 ppm or more and 2,000 ppm or less. By including the boron compound in the above range in the heat-sealing layer, the heat-sealing film undergoes crosslinking during heat-sealing, and the heat-sealing strength can be further increased.

  The heat-sealing film has excellent non-sorption properties as described above, and can be suitably used for packaging bags.

  In the heat-sealing film, the heat-sealing layer is made to face each other, and the heat-sealing strength obtained by press-bonding for 1 second at a temperature of 185 ° C. and a pressure of 0.1 MPa using a hot plate heat sealer is 10 N / 15 mm. It is good to be above. The heat-sealing film can obtain excellent heat-sealing strength by heat-sealing, and can be suitably used as a heat-sealing film for packaging bags having high aroma retention.

  Another invention made in order to solve the above-mentioned problems is a packaging obtained by molding the heat-sealing film, with the heat-sealing layer of the heat-sealing film as the inside, and heat-sealing the heat-sealing layer. It is a bag. According to the packaging bag, since it is heat-sealed with excellent strength and further has a heat-sealing layer having excellent non-sorption property of the scent component on the inner surface, excellent scent retention can be exhibited.

  The moisture content of the heat-sealing layer at the time of heat sealing is preferably 0.1% by mass or more and 4.0% by mass or less. By setting the moisture content of the heat-sealing layer at the time of heat sealing to be in the above range, foaming at the time of heat sealing can be suppressed, so that a packaging bag with an excellent appearance of the sealed portion can be obtained.

  The packaging bag may have a zipper. Thus, according to the packaging bag provided with the zipper, the packaging bag can be resealed, and the storage stability of the contents can be improved.

  In the packaging bag, the contents to be packaged may be at least one selected from the group consisting of confectionery, tea leaves, coffee, spices and tobacco. Since the packaging bag has excellent aroma retention as described above, it is particularly suitable as a packaging bag for foods and the like that require aroma retention.

  As described above, the heat sealing film of the present invention has excellent non-sorption properties for scent components. Therefore, the packaging bag using this heat-sealing film has extremely high aroma retention, and therefore, it is suitably used as a packaging bag for foods and the like in which aroma retention such as confectionery, tea leaves, coffee, spices and tobacco is important. be able to.

  Hereinafter, embodiments of the present invention will be described in detail in the order of a heat sealing film and a packaging bag.

<Film for heat sealing>
The heat sealing film of the present invention includes a heat-sealing layer containing EVOH. The heat sealing film may be a single-layer film of the heat-sealing layer or a multilayer film having a layer structure of two or more layers. However, in the case of a multilayer film, at least one outermost layer is composed of the above heat-sealing layer.

  The thickness of the heat sealing film as a whole is not particularly limited, and is appropriately set depending on the number of layers, usage, and the like. For example, in the case of a multilayer film, the thickness is about 2 μm or more and 1 mm or less. By setting the thickness of the heat sealing film within the above range, a film having excellent mechanical strength, gas barrier properties, flexibility, and workability can be obtained.

<Heat-fusion layer>
The heat-sealing layer contains EVOH as an essential component as described above, and may contain a metal salt, a boron compound, a phosphoric acid compound, a carboxylic acid, and other optional components as suitable components. Details of each component will be described later.

  The equilibrium moisture content at a temperature of 23 ° C. and a relative humidity of 50% of the heat-sealing layer is 0.5% by mass or more and 5.0% by mass or less, and 1.0% by mass or more and 3.5% by mass or less. preferable. According to the heat sealing film, since the heat-sealing layer has an equilibrium moisture content in the above range, a certain amount of water can be contained in the heat-sealing layer. As a result, in the heat-sealing layer, A structure in which water molecules are arranged in voids between EVOH molecular chains can be adopted. Therefore, according to the heat sealing film, adsorption of the scent component can be effectively suppressed by reducing the gap in the heat-sealing layer with water molecules. In particular, the surface of the heat-sealing layer, which has increased polarity due to the arrangement of water molecules, extremely effectively suppresses the sorption of low-polar scent components such as hydrocarbon compounds. Can be demonstrated.

  When the equilibrium moisture content in the heat-fusible layer is less than the above lower limit, the amount of water molecules that can be present in the heat-fusible layer is insufficient, and the non-sorption property is not sufficiently improved. On the other hand, when the equilibrium moisture content exceeds the above upper limit, the heat-sealing property tends to be lowered, for example, the heat-sealing layer foams during heat sealing, resulting in poor appearance. Further, when the equilibrium moisture content exceeds the above upper limit, the heat-sealing layer is swollen by moisture, and the scent component is easily sorbed.

  In addition, adjustment of the equilibrium moisture content in a heat-fusion layer can be performed by adjusting the ethylene content and saponification degree of EVOH, which will be described later, or by blending additives. Moreover, an equilibrium moisture content is a value calculated | required based on the measuring method of 8.3 "equilibrium moisture content" of JIS-L1015-2010.

  Moreover, as a moisture content of a heat-fusion layer, 0.1 mass% or more and 4.0 mass% or less are preferable, and 0.2 mass% or more and 3.0 mass% or less are more preferable. By setting the moisture content of the heat-fusible layer in the above range, the non-sorption property and heat sealability of the scent component can be achieved at a high level. When this moisture content is less than the above lower limit, the increase in the polarity of the surface of the heat-sealing layer due to water molecules is small, and in particular, the improvement in the non-sorption property for the low-polarity scent component is not sufficiently exhibited. On the other hand, if the moisture content exceeds the above upper limit, foaming is likely to occur due to vaporization of moisture in the heat-sealing layer at the time of heat sealing, and heat sealability may be deteriorated or the appearance may be deteriorated. . Moreover, when this moisture content exceeds the said upper limit, a heat sealing | fusion layer will swell with a water | moisture content and it will become easy to sorb | suck a scent component. In addition, it is preferable to set it as this range as the moisture content of this heat sealing | fusion layer especially at the time of heat sealing.

The density of the heat fusion layer is preferably 1.10 g / cm ³ or more, more preferably 1.20 g / cm ³ or less. By setting the density of the heat-fusible layer to the above lower limit or more, voids in the layer are reduced, and as a result, it is possible to suppress the adsorption of the scent component into the voids. It will be improved. In addition, when the density of the heat-fusible layer exceeds the above upper limit, there is a possibility that inconveniences such as deterioration of flexibility and moldability may occur.

  The thickness of the heat fusion layer is preferably 2 μm or more and 100 μm or less, and more preferably 5 μm or more and 60 μm or less. By setting the thickness of the heat-sealing layer in the above range, it is possible to achieve both the non-sorption property and the heat sealing property of the heat sealing film at a high level. If this thickness is less than the above lower limit, the layer is too thin to perform adhesion with sufficient sealing strength even by heat sealing, resulting in a decrease in moldability or a decrease in the strength of the resulting packaging bag. Sometimes. Conversely, if this thickness exceeds the above upper limit, the amount of the scent component adsorbed in the heat-sealing layer increases, so that the sorption is increased, the fragrance retention of the resulting packaging bag is reduced, There is a risk of pinholes being generated by bending. Here, the thickness of the layer is obtained by dividing the heat-sealing film into 5 parts in the width direction, measuring the thickness of the central part, and averaging the thicknesses of 5 points.

<EVOH>
EVOH contained in the heat-fusion layer has an ethylene unit and a vinyl alcohol unit as main structural units. The EVOH may contain one or more other structural units in addition to the ethylene unit and the vinyl alcohol unit. Moreover, you may mix and use 2 or more types of EVOH from which ethylene content mentioned later, the saponification degree, the presence or absence of modification | denaturation, or the kind of modification | denaturation differs.

  This EVOH is usually obtained by polymerizing ethylene and a vinyl ester and saponifying the resulting ethylene-vinyl ester copolymer.

  The lower limit of the ethylene content of EVOH (that is, the ratio of the number of ethylene units to the total number of monomer units in EVOH) is 20 mol%, preferably 25 mol%, particularly preferably 30 mol%. On the other hand, the upper limit of the ethylene content of EVOH is 70 mol%, more preferably 60 mol%, and particularly preferably 50 mol%. When the ethylene content of EVOH is smaller than the above lower limit, the heat sealability and melt moldability at low temperatures of the heat seal film are lowered. On the contrary, when the ethylene content of EVOH exceeds the upper limit, the non-sorption property of the heat sealing film is lowered. Here, when EVOH consists of a blend of two or more types of EVOH having different ethylene contents, the average value calculated from the blending mass ratio is taken as the ethylene content.

  The lower limit of the saponification degree of EVOH (that is, the ratio of the number of vinyl alcohol units to the total number of vinyl alcohol units and vinyl ester units in EVOH) is 90 mol%, preferably 95 mol%, and 99 mol% Particularly preferred. On the other hand, the upper limit of the saponification degree of EVOH is preferably 100.0 mol%. When the saponification degree of EVOH is smaller than the above lower limit, the non-sorption property of the scent component is low, and the thermal stability becomes insufficient, so that gels and blisters are likely to occur during melt molding. Here, when EVOH consists of a blend of two or more types of EVOH having different saponification degrees, the average value calculated from the blending mass ratio is taken as the saponification degree.

  EVOH may have structural units other than ethylene units and vinyl alcohol units. Examples of such structural units include the following structural units (Ia), (Ib), and (Ic).

In formula (Ia), R ¹ , R ² and R ³ each independently represent a hydrogen atom, an aliphatic hydrocarbon group having 1 to 10 carbon atoms, an alicyclic hydrocarbon group having 3 to 10 carbon atoms, or a carbon number. It represents 6 to 10 aromatic hydrocarbon group or hydroxyl group. In addition, a pair of R ¹ , R ² and R ³ may be bonded (except when a pair of R ¹ , R ² and R ³ are both hydrogen atoms). The aliphatic hydrocarbon group having 1 to 10 carbon atoms, the alicyclic hydrocarbon group having 3 to 10 carbon atoms, or the aromatic hydrocarbon group having 6 to 10 carbon atoms has a hydroxyl group, a carboxyl group, or a halogen atom. You may do it.

In formula (Ib), R ⁴ , R ⁵ , R ⁶ and R ⁷ are each independently a hydrogen atom, an aliphatic hydrocarbon group having 1 to 10 carbon atoms, or an alicyclic hydrocarbon group having 3 to 10 carbon atoms. Represents an aromatic hydrocarbon group or a hydroxyl group having 6 to 10 carbon atoms. R ⁴ and R ⁵ or R ⁶ and R ⁷ may be bonded (except when R ⁴ and R ⁵ or R ⁶ and R ⁷ are both hydrogen atoms). In addition, the aliphatic hydrocarbon group having 1 to 10 carbon atoms, the alicyclic hydrocarbon group having 3 to 10 carbon atoms, or the aromatic hydrocarbon group having 6 to 10 carbon atoms is a hydroxyl group, an alkoxy group, a carboxyl group, or a halogen atom. You may have an atom.

In formula (Ic), R ⁸ , R ⁹ and R ¹⁰ are each independently a hydrogen atom, an aliphatic hydrocarbon group having 1 to 10 carbon atoms, an alicyclic hydrocarbon group having 3 to 10 carbon atoms, or a carbon number. It represents 6 to 10 aromatic hydrocarbon group or hydroxyl group. Further, a pair of R ⁸ , R ⁹ and R ¹⁰ may be bonded (except when a pair of R ⁸ , R ⁹ and R ¹⁰ are both hydrogen atoms). The aliphatic hydrocarbon group having 1 to 10 carbon atoms, the alicyclic hydrocarbon group having 3 to 10 carbon atoms, or the aromatic hydrocarbon group having 6 to 10 carbon atoms has a hydroxyl group, a carboxyl group, or a halogen atom. You may do it.

  In the structural units (Ia), (Ib) and (Ic), examples of the aliphatic hydrocarbon group having 1 to 10 carbon atoms include an alkyl group and an alkenyl group, and an alicyclic hydrocarbon having 3 to 10 carbon atoms. Examples of the group include a cycloalkyl group and a cycloalkenyl group, and examples of the aromatic hydrocarbon group having 6 to 10 carbon atoms include a phenyl group.

  The modified EVOH containing the structural unit (Ia) is synthesized by, for example, partially leaving an ester group without completely performing saponification. A typical vinyl ester for producing the structural unit (Ia) is vinyl acetate, and other vinyl esters include fatty acid vinyl esters such as vinyl propionate and vinyl pivalate.

  The method for synthesizing the modified EVOH containing the structural unit (Ib) is not particularly limited, but can be synthesized by reacting a monovalent epoxy compound with an ethylene-vinyl alcohol copolymer. Examples of the monovalent epoxy compound include 1,2-epoxybutane, 2,3-epoxybutane, epoxypropane, epoxyethane, and glycidol.

  The modified EVOH containing the structural unit (Ib) can be specifically produced by the method described in WO02 / 092643.

  The method for synthesizing the modified EVOH containing the structural unit (Ic) is not particularly limited, but the structural unit (Ic) is derived when a vinyl ester monomer and ethylene are copolymerized to produce an ethylene-vinyl ester copolymer. And a method of saponifying the obtained copolymer after adding a monomer to be copolymerized. Examples of the monomer from which the structural unit (Ic) is derived include alkene monomers such as propylene, butylene, pentene and hexene, 3-propen-1-ol, 3-acyloxy-1-propene, 3-acyloxy-1-butene, 4-acyloxy-1-butene, 3,4-diacyloxy-1-butene, 3-acyloxy-4-ol-1-butene, 4-acyloxy-1-buten-3-ol, 3-acyloxy-2-methyl- 1-butene, 3-acyloxy-4-methyl-1-butene, 4-acyloxy-2-methyl-1-butene, 4-acyloxy-3-methyl-1-butene, 3,4-diacyloxy-2-methyl- 1-butene, 4-penten-2-ol, 5-penten-1-ol, 4,5-dihydroxy-1-pentene, 4-acyloxy-1-pentene, 5- Siloxy-1-pentene, 4,5-diasiloxy-1-pentene, 4-hydroxy-3-methyl-1-pentene, 5-hydroxy-3-methyl-1-pentene, 4,5-dihydroxy-3-methyl- 1-pentene, 5,6-dihydroxy-1-hexene, 4-hydroxy-1-hexene, 5-hydroxy-1-hexene, 6-hydroxy-1-hexene, 4-acyloxy-1-hexene, 5-acyloxy- Examples thereof include vinyl ester monomers such as 1-hexene, 6-acyloxy-1-hexene, and 5,6-diasiloxy-1-hexene.

  In addition, the modified EVOH containing the structural unit (Ia), (Ib) or (Ic) may be other copolymer components such as (meth) acrylic acid and methyl (meth) acrylate as long as the purpose is not impaired. And unsaturated carboxylic acids such as ethyl (meth) acrylate or esters thereof; vinylsilane compounds such as vinyltrimethoxysilane; unsaturated sulfonic acids or salts thereof; alkylthiols; and vinylpyrrolidones such as N-vinylpyrrolidone You may go out.

  Moreover, as EVOH used for this invention, what has a carboxylic acid unit and a lactone ring unit at the terminal is preferable. The ratio of the total amount of the terminal carboxylic acid units and lactone ring units to the total amount of ethylene units, vinyl alcohol units and vinyl ester units is preferably 0.05 mol% or more and 0.30 mol% or less, preferably 0.07 mol%. More preferably, it is 0.20 mol% or less. When the terminal of EVOH has a small amount of carboxylic acid unit and lactone ring unit, a reaction between the carboxylic acid and lactone ring and a hydroxyl group occurs, and the heat seal strength at the time of heat sealing at a low temperature can be further increased. In addition, when content of this terminal carboxylic acid unit and a lactone ring unit exceeds the said upper limit, since it becomes easy to adsorb | suck a cationic fragrance component, there exists a possibility that non-sorption property may fall.

  The content of the terminal carboxylic acid unit and the lactone ring unit can be controlled by conditions such as composition and temperature during polymerization. Further, in the copolymerization reaction of ethylene and vinyl ester, a terminal carboxylic acid unit and a method of adding a mercapto group-containing carboxylic acid such as 3-mercaptopropionic acid, a method of oxidizing EVOH with hydrogen peroxide, and the like. It is possible to control the content of the lactone ring unit.

The lower limit of the solubility parameter (SP value) of EVOH used in the present invention is preferably 11.0, and more preferably 11.5. On the other hand, the upper limit of the solubility parameter is preferably 15.0, and more preferably 14.0. By setting the solubility parameter of EVOH within the above range, compatibility with hydrocarbon-based scent components such as limonene and terpinene, which are particularly desired to suppress sorption, can be lowered, and the non-sorption property of these components is increased. be able to. In addition, when this solubility parameter exceeds the said upper limit, compatibility with the scent component which has polarity will increase, As a result, the non-sorption property of these components may fall. Here, the solubility parameter is a value determined by the FEDORS method, and the unit is (cal / cm ³ ) ^1/2 .

  The upper limit of the melting point of EVOH used in the present invention is preferably 170 ° C, and more preferably 168 ° C. By setting the melting point of EVOH to the above upper limit or less, the heat sealability can be further enhanced. On the other hand, the lower limit of the melting point of EVOH is not particularly limited, but is preferably 150 ° C. from the viewpoint of improving heat resistance, and more preferably 155 ° C.

  In the differential scanning calorimetry in which the heat-sealing layer used in the present invention was measured from 30 ° C. to 300 ° C. at a rate of temperature increase of 10 ° C./min, the half-value width of the endothermic peak indicating EVOH melting was 5.0 ° C. or more and 20 It is preferably 0.0 ° C. or lower, and more preferably 7.0 ° C. or higher and 18.0 ° C. or lower. According to the heat sealing film, by using EVOH having a specific width in the melting temperature as described above, it is possible to increase the sealing strength by heat sealing at a low temperature and to suppress thinning at the time of heat sealing. .

  In addition, this value is adjusted by adjusting the ethylene content of EVOH, the saponification degree, the mass average molecular weight, the number average molecular weight, the moisture content of the heat fusion layer, and the additives contained in the heat fusion layer, for example. Can be controlled.

  Next, a method for producing EVOH will be specifically described. The copolymerization method of ethylene and vinyl ester is not particularly limited, and for example, any of solution polymerization, suspension polymerization, emulsion polymerization, and bulk polymerization may be used. Moreover, any of a continuous type and a batch type may be sufficient.

  As vinyl ester used for polymerization, fatty acid vinyl such as vinyl acetate, vinyl propionate and vinyl pivalate can be used.

  In the above polymerization, a monomer that can be copolymerized in addition to the above components, for example, alkenes other than those described above; unsaturated acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, or anhydrides thereof Products, salts, mono- or dialkyl esters, etc .; nitriles such as acrylonitrile and methacrylonitrile; amides such as acrylamide and methacrylamide; olefin sulfonic acids such as vinyl sulfonic acid, allyl sulfonic acid and methallyl sulfonic acid; Vinyl ethers, vinyl ketone, N-vinyl pyrrolidone, vinyl chloride, vinylidene chloride and the like can be copolymerized in a small amount. Moreover, a vinyl silane compound can be contained as 0.0002 mol% or more and 0.2 mol% or less as a copolymerization component. Here, examples of the vinylsilane compound include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri (β-methoxy-ethoxy) silane, and γ-methacryloyloxypropylmethoxysilane. Of these, vinyltrimethoxysilane and vinyltriethoxysilane are preferably used.

  The solvent used for the polymerization is not particularly limited as long as it is an organic solvent that can dissolve ethylene, vinyl ester, and ethylene-vinyl ester copolymer. As such a solvent, for example, alcohols such as methanol, ethanol, propanol, n-butanol and tert-butanol; dimethyl sulfoxide and the like can be used. Among them, methanol is particularly preferable in that removal and separation after the reaction is easy.

  Examples of the catalyst used for polymerization include 2,2-azobisisobutyronitrile, 2,2-azobis- (2,4-dimethylvaleronitrile), 2,2-azobis- (4-methoxy-2,4). -Dimethylvaleronitrile), 2,2-azobis- (2-cyclopropylpropionitrile) and other azonitrile initiators; isobutyryl peroxide, cumylperoxyneodecanoate, diisopropylperoxycarbonate, di-n- Organic peroxide initiators such as propyl peroxydicarbonate, t-butyl peroxyneodecanoate, lauroyl peroxide, benzoyl peroxide, t-butyl hydroperoxide, and the like can be used.

  As superposition | polymerization temperature, it is 20-90 degreeC, Preferably it is 40-70 degreeC. The polymerization time is 2 to 15 hours, preferably 3 to 11 hours. The polymerization rate is 10 to 90%, preferably 30 to 80%, relative to the charged vinyl ester. The resin content in the solution after polymerization is 5 to 85%, preferably 20 to 70%.

  After polymerization for a predetermined time or after reaching a predetermined polymerization rate, a polymerization inhibitor is added as necessary, and after removing unreacted ethylene gas, unreacted vinyl ester is removed. As a method for removing the unreacted vinyl ester, for example, the above copolymer solution is continuously supplied from the upper part of the tower filled with Raschig rings at a constant rate, and an organic solvent vapor such as methanol is blown from the lower part of the tower. A method may be employed in which a mixed vapor of an organic solvent such as methanol and unreacted vinyl ester is distilled from the top, and a copolymer solution from which unreacted vinyl ester has been removed is removed from the bottom of the column.

  Next, an alkali catalyst is added to the copolymer solution to saponify the copolymer. The saponification method can be either a continuous type or a batch type. As this alkali catalyst, for example, sodium hydroxide, potassium hydroxide, alkali metal alcoholate and the like are used.

  As the conditions for saponification, for example, in the case of a batch system, the copolymer solution concentration is 10 to 50%, the reaction temperature is 30 to 65 ° C., and the amount of catalyst used is 0.02 to 1.0 per mole of vinyl ester structural unit. Mole, saponification time is 1-6 hours.

  EVOH after the saponification reaction contains an alkali catalyst, by-product salts such as sodium acetate and potassium acetate, and other impurities. Therefore, it is preferable to remove these by neutralization and washing as necessary. Here, when EVOH after the saponification reaction is washed with water containing almost no metal ions such as ion-exchanged water, chloride ions, or the like, a part of sodium acetate, potassium acetate or the like may remain.

<Other thermoplastic resins>
In addition to EVOH, the thermoplastic layer may contain other thermoplastic resins blended. Other thermoplastic resin is not particularly limited, polyolefin, polyamide, polyester, polystyrene, polyvinyl chloride, poly (meth) acrylate, polyvinylidene chloride, polyacetal, polycarbonate, polyvinyl acetate, polyurethane, polyacrylonitrile, Polyketone etc. are mentioned. Various copolymers can also be used.

  The method for blending EVOH and other thermoplastic resins is not particularly limited. The resin pellets can be dry blended and used for melt molding as they are, or more preferably melt-kneaded with a Banbury mixer, single-screw or twin-screw extruder, etc., and pelletized before being used for melt molding.

  In the heat-sealing layer, at least a part of EVOH may be cross-linked from the viewpoint of improving gas barrier properties and non-sorption properties. The EVOH in the heat-fusible layer can be cross-linked by leaving it in the air for a long time, but is usually irradiated with electron beam, X-ray, γ-ray, ultraviolet ray, visible ray, etc. or heated. Therefore, it is preferable to perform crosslinking.

<Other ingredients>
Hereinafter, each component (a metal salt, a boron compound, a phosphoric acid compound, a carboxylic acid, and other optional components as suitable components) included as components other than EVOH in the above-mentioned heat-fusible layer will be described.

<Metal salt>
According to the heat sealing film, by including a metal salt in the heat-sealing layer, the polarity is further increased, and the non-sorption property of the low-polar scent component can be further increased. Moreover, interlayer adhesion and heat sealability are improved by including a metal salt in the heat-fusible layer.

  Although it does not specifically limit as a metal salt, An alkali metal salt or alkaline-earth salt is preferable at the point which raises interlayer adhesiveness more. Among these, alkali metal salts are more preferable.

  The alkali metal salt is not particularly limited, and examples thereof include aliphatic carboxylates such as lithium, sodium, and potassium, aromatic carboxylates, phosphates, and metal complexes. Specific examples of the alkali metal salt include sodium acetate, potassium acetate, sodium phosphate, lithium phosphate, sodium stearate, potassium stearate, sodium salt of ethylenediaminetetraacetic acid, and the like. Among these, sodium acetate, potassium acetate, and sodium phosphate are particularly preferable because they are easily available.

  The alkaline earth metal salt is not particularly limited, and examples thereof include acetates or phosphates such as magnesium, calcium, barium, and beryllium. Among these, magnesium or calcium acetate or phosphate is particularly preferable because it is easily available. When such an alkaline earth metal salt is contained, there is also an advantage that the die adhesion amount of a molding machine for a resin that has been thermally deteriorated during melt molding can be reduced.

  The lower limit of the content (metal element equivalent content) of the metal salt in the heat-fusible layer is preferably 1 ppm, more preferably 5 ppm, still more preferably 10 ppm, and particularly preferably 20 ppm. On the other hand, the upper limit of the content of the metal salt is preferably 10,000 ppm, more preferably 5,000 ppm, further preferably 1,000 ppm, and particularly preferably 500 ppm. When the content of the metal salt is less than the above lower limit, a sufficient increase in polarity does not occur, and the non-sorption property for a low-polar fragrance component is not sufficiently improved. On the other hand, when the content of the metal salt exceeds the above upper limit, a scent component having a high polarity may be easily adsorbed, or the resulting film may be intensely colored to deteriorate the appearance.

<Boron compound>
Moreover, by containing a boron compound in the heat-sealing layer, a crosslinked structure is formed during heat sealing, and the heat sealing strength is further improved. Specifically, when a boron compound is added to a resin composition composed of EVOH or the like, it is considered that a chelate compound is generated between the EVOH or the like and the boron compound. It is possible to improve thermal stability and mechanical properties, and the above-mentioned chelate structure can be cross-linked between the polymer chains of EVOH, whereby the heat seal strength can be further improved. The boron compound is not particularly limited, and examples thereof include boric acids, boric acid esters, borates, and borohydrides. Specifically, examples of boric acids include orthoboric acid (H ₃ BO ₃ ), metaboric acid, and tetraboric acid, and examples of boric acid esters include triethyl borate and trimethyl borate. Examples of the borate include alkali metal salts, alkaline earth metal salts, and borax of the various boric acids. Of these, orthoboric acid is preferred.

  As a minimum of content (in boron compound conversion) in a heat fusion layer of a boron compound, 50 ppm is preferred and 100 ppm is still more preferred. On the other hand, the upper limit of the boron compound content is preferably 2,000 ppm, more preferably 1,800 ppm, and even more preferably 1,600 ppm. If the content of the boron compound is less than the above lower limit, the effect of improving the strength by adding the boron compound may not be obtained. On the contrary, when the content of the boron compound exceeds the above upper limit, gelation tends to occur and there is a risk of forming defects.

<Phosphate compound>
By containing a phosphoric acid compound in the heat-fusible layer, the heat stability and heat-sealability during melt molding of the heat-sealing film can be improved. Moreover, since the polarity of a heat-fusion layer increases, the non-sorption property with respect to a low polarity fragrance component improves. It does not specifically limit as a phosphoric acid compound, For example, various acids, such as phosphoric acid and phosphorous acid, its salt, etc. are mentioned. The phosphate may be contained in any form of, for example, a first phosphate, a second phosphate, and a third phosphate, and is not particularly limited as a counter cation species, but an alkali metal ion Or alkaline earth metal ions are preferred. In particular, sodium dihydrogen phosphate, potassium dihydrogen phosphate, sodium hydrogen phosphate, or potassium hydrogen phosphate is preferred because of its high thermal stability improving effect.

  As a minimum of content (phosphoric acid radical conversion content) in a heat fusion layer of a phosphoric acid compound, 1 ppm is preferred, 10 ppm is more preferred, and 30 ppm is still more preferred. On the other hand, the upper limit of the phosphoric acid compound content (phosphoric acid radical content) is preferably 10,000 ppm, more preferably 1,000 ppm, and even more preferably 300 ppm. If the content of the phosphoric acid compound is less than the above lower limit, coloring during melt molding may become intense. In particular, since the tendency is remarkable when the heat history is accumulated, the heat-sealing film may be poor in recoverability. On the other hand, if the content of the phosphoric acid compound exceeds the above upper limit, there is a risk that gels and blisters of the molded product are likely to occur.

<Carboxylic acid>
By containing carboxylic acid in the heat-fusible layer, there is an effect of controlling the pH of the resin composition forming the heat-fusible layer, preventing gelation and improving the thermal stability. Moreover, since the polarity of a heat-fusion layer increases, the non-sorption property with respect to a low polarity fragrance component improves. As the carboxylic acid, those having a pKa at 25 ° C. of 3.5 or more are preferable. In particular, as the carboxylic acid, acetic acid or lactic acid is preferable from the viewpoint of cost and the like.

  The lower limit of the content of the carboxylic acid in the heat-fusible layer is preferably 1 ppm, more preferably 10 ppm, and even more preferably 50 ppm. On the other hand, the upper limit of the carboxylic acid content is preferably 10,000 ppm, more preferably 1,000 ppm, and even more preferably 500 ppm. If the carboxylic acid content is less than the lower limit, coloring may occur during melt molding. Conversely, if the content of carboxylic acid exceeds the above upper limit, the adhesiveness during heat sealing may be insufficient.

<Other ingredients>
The said heat-fusion layer can contain other various components (additives) as needed. Examples of such additives include antioxidants, plasticizers, heat stabilizers, ultraviolet absorbers, antistatic agents, lubricants, colorants, fillers, etc., and these are effective in the present invention. It can be blended as long as it is not inhibited. Specific examples of each additive include the following.

  Antioxidant: 2,5-di-t-butylhydroquinone, 2,6-di-t-butyl-p-cresol, 4,4′-thiobis (6-t-butylphenol), 2,2′-methylenebis ( 4-methyl-6-t-butylphenol), octadecyl-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) propionate, 4,4′-thiobis (6-t-butylphenol), etc. .

  UV absorber: ethylene-2-cyano-3,3′-diphenyl acrylate, 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- (2′-hydroxy-5′-methylphenyl) benzo Triazole, 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- (2′-hydroxy-3′-t-butyl-5′-methylphenyl) -5-chlorobenzotriazole, 2-hydroxy -4-methoxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, and the like.

  Plasticizer: Dimethyl phthalate, diethyl phthalate, dioctyl phthalate, wax, liquid paraffin, phosphate ester, etc.

  Antistatic agents: pentaerythritol monostearate, sorbitan monopalmitate, sulfated polyolefins, polyethylene oxide, carbowax, etc.

  Lubricant: Ethylene bisstearamide, butyl stearate, etc.

  Colorant: Carbon black, phthalocyanine, quinacridone, indoline, azo pigment, Bengala, etc.

  Filler: Glass fiber, asbestos, ballastite, calcium silicate, etc.

<Other layers>
When the heat sealing film has a multilayer structure, the layers other than the heat fusion layer include polyolefin, polyamide, polyester, polystyrene, polyvinyl chloride, poly (meth) acrylic acid ester, polyvinylidene chloride, polyacetal, polycarbonate, In addition to resins such as polyvinyl acetate, polyurethane, polyacrylonitrile, and various copolymers, paper, metals such as aluminum, metal oxides such as silica and alumina, and the like can be used. The other layer may be a combination of layers made of these materials.

  Specific examples of the multilayer structure in the heat-sealing film include a three-layer structure including a heat fusion layer / a metal layer / a polyester layer. Thus, by providing a metal layer as another layer in the heat sealing film, the non-sorption property and gas barrier property when used as a packaging bag or the like can be further enhanced. Further, as other specific multilayer structures, for example, heat fusion layer / polyamide layer / polyester layer, heat fusion layer / polyamide layer / polyolefin layer, heat fusion layer / paper layer / polyolefin layer, etc. Can do.

  In addition, it does not specifically limit as thickness of each other layer, For example, they are 2 micrometers or more and about 200 micrometers or less.

<Method for producing heat sealing film>
The production method of the heat seal film of the present invention is not particularly limited, and a known production method of a single layer or multilayer film, for example, extrusion method, coextrusion method, dry lamination method, extrusion coating method, coextrusion coating method, etc. Can be adopted. Specifically, when the heat-sealing film is a multilayer, a method of co-extrusion of the heat-sealing layer and other layers, a method of extrusion-coating the heat-sealing layer on the other layer, heat fusion Examples thereof include a method of dry laminating a film composed of layers and a film composed of other layers. In the case of a multilayer film, an adhesive or an adhesive resin can be used as necessary when laminating. In addition, the other layer in the case of forming from a heat-fusion layer or a resin may be oriented by uniaxial stretching or biaxial stretching. Moreover, when laminating | stacking said metal and a metal oxide on the said film for heat seals, a well-known vapor deposition method can be used.

<Applications and performance of heat seal films>
The heat sealing film of the present invention has excellent non-sorption properties as described above, and can be suitably used for packaging bags.

  In the heat-sealing film, the heat-sealing strength obtained by bringing the heat-sealing layers to face each other and press-bonding them for 1 second under conditions of a temperature of 185 ° C. and a pressure of 0.1 MPa using a hot plate heat sealer is 10 N / 15 mm or more. It is good to be. In addition, the heat sealing | fusion layers made to face may be the same and may differ. The heat-sealing film can obtain excellent heat-sealing strength by heat-sealing, and can be suitably used as a heat-sealing film for packaging bags having high aroma retention. The heat seal strength is a value measured according to JIS-Z1707.

<Packaging bag>
The heat-sealing film can be made into a container and a package (bag, cup, tube, tray, bottle, etc.) with the heat-sealing layer inside by heat-sealing the heat-sealing layers. it can. As described above, the heat-sealing film of the present invention can be heat-sealed with high strength, and the heat-sealing layer is excellent in the non-sorption property of the scent component. Bags and the like can exhibit excellent scent retention.

  The heat sealing method is not particularly limited, and a known method can be used. Examples thereof include a heat sealing method using a hot plate heat sealer, impulse sealer, ultrasonic sealer, friction heat sealer, dielectric heating sealer, and the like. The temperature at the time of heat sealing is not particularly limited, but is preferably not less than the melting point of the heat-sealing layer and not more than (melting point + 30 ° C.) from the viewpoint of heat sealing strength and appearance defect prevention. The pressure for heat sealing is not particularly limited, but is preferably 0.01 MPa or more and 1.0 MPa or less from the viewpoint of heat sealing strength and appearance defect prevention. Although it does not specifically limit as time to heat seal, It is preferable from the point of heat seal intensity | strength and productivity that it is 0.05 second or more and 5 second or less.

  As described above, the moisture content of the heat-sealing layer of the heat-sealing film when the heat-sealing film is heat-sealed to form a packaging bag or the like is 0.1% by mass or more and 4% by mass or less. Preferably, 0.2 mass% or more and 3 mass% or less are more preferable. By keeping the moisture content of the heat-sealing layer at the time of heat sealing in the above range, it is possible to suppress the maintenance of the appearance of the seal portion and the decrease in the seal strength. If the moisture content exceeds the above upper limit, foaming is likely to occur due to vaporization of moisture in the heat-sealing layer during heat sealing, resulting in a decrease in the appearance of the heat-sealed part or a decrease in heat-sealability. There is a risk of doing so. Moreover, when this moisture content is below the said minimum, the non-sorption property immediately after shape | molding a packaging bag etc. may fall. If the contents are filled immediately after molding, the aromatic components derived from the contents are easily sorbed on the heat-sealing layer.

  The packaging bag may have a zipper. Thus, according to the packaging bag provided with the zipper, it can be sealed again even after being opened once, so that the packaging bag can be stored for a long time after being opened, and the packaging bag can be used repeatedly.

  In the packaging bag, the method for bonding the heat sealing film and the zipper is not particularly limited, and examples thereof include a method of bonding the heat-sealing layer and the zipper in the heat sealing film by heat sealing. .

  Examples of the contents (packaged items) in the packaging bag include foods, beverages, pharmaceuticals, cosmetics, fragrances, toiletry products and the like containing fragrant components, and in particular, confectionery, tea leaves, coffee, spices and tobacco. It is good that it is at least one selected from the group. Since the packaging bag has excellent aroma retention as described above, it is particularly suitable as a packaging bag for foods and the like that require aroma retention.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples.

[1] Ethylene content of EVOH
^It calculated | required by < ¹ > H-NMR measurement. That is, EVOH resin pellets described in each of Examples and Comparative Examples were dissolved in dimethyl sulfoxide (DMSO) -d ₆ and used at 80 ° C. using ¹ H-NMR of 500 MHz (manufactured by JEOL Ltd., GX-500). The ethylene content was calculated from the methine protons of ethylene units, vinyl alcohol units and vinyl ester units (from a peak intensity ratio of 0.6 to 2.1 ppm).

[2] Saponification degree of EVOH
^It calculated | required by < ¹ > H-NMR measurement. That is, EVOH resin pellets described in each of Examples and Comparative Examples were dissolved in DMSO-d ₆ and measured at 80 ° C. using 500 MHz ¹ H-NMR (manufactured by JEOL Ltd., GX-500). It was calculated from the peak intensity ratio of the side chain site proton of the ester unit and the methine proton (3.15 to 4.15 ppm) of the vinyl alcohol unit.

[3] Melting point of EVOH Obtained by differential scanning calorimetry. That is, the EVOH resin pellets described in each example and comparative example were rapidly heated from 30 ° C. to 220 ° C. at a rate of 10 ° C./min, and then rapidly cooled to 30 ° C. at 100 ° C./min, according to JIS-K7121. Then, differential scanning calorimetry (Seiko Denshi Kogyo Co., Ltd. differential scanning calorimeter (DSC) RDC220 / SSC5200H type) was performed again from 30 ° C. to 220 ° C. at a heating rate of 10 ° C./min. Indium and lead were used for temperature calibration. The melting peak temperature (Tpm) referred to in the above JIS was determined from the 2nd run chart, and this was taken as the melting point.

[4] EVOH terminal carboxylic acid unit content and lactone ring unit content
^It calculated | required by < ¹ > H-NMR measurement. That is, EVOH resin pellets described in each Example and Comparative Example were dissolved in a water / methanol solvent, and measured at 80 ° C. using ¹ H-NMR (GX-500, manufactured by JEOL Ltd.) ¹ H of 500 MHz. , 0.7-2.0 ppm methylene hydrogen integral value (I ₁ ), 2.2-2.5 ppm peak integral value (I ₂ ), 2.5-2.65 ppm peak integral value (I ₃ ), the terminal carboxylic acid unit content and the lactone ring unit content were calculated by the following formula. Here, the integral values (I ₂ ) and (I ₃ ) relate to peaks derived from terminal carboxylic acid units and lactone ring units. In addition, Et described in the following formula is ethylene content.
Terminal carboxylic acid unit content and lactone ring unit content (mol%)
= (Et + 100) · (2I ₂ + I ₃ ) / {200I ₂ + (2I ₂ + I ₃ ) / 2}

[5] Content of metal salt in heat-fusible layer Determined by ICP emission spectroscopic analysis. That is, the heat-sealing layer described in each Example and Comparative Example was pulverized by freeze pulverization, 10 g of the obtained powder and 50 mL of ion-exchanged water were put into a 100 mL Erlenmeyer flask with a stopper, and a cooling condenser was attached. Stir at 10 ° C. for 10 hours, extract with heating, extract 2 mL of the resulting extract diluted with 8 mL of ion-exchanged water, analyze the contained metal using an ICP emission spectrometer (“Optima 4300 DV” manufactured by PerkinElmer), The ion content was quantified to calculate the metal salt content.

[6] Content of boron compound in heat-sealed layer Determined by atomic absorption analysis. That is, 100 g of the heat-sealing layer described in each example and comparative example was put in a magnetic crucible and ashed in an electric furnace, and the obtained ash was dissolved in 200 mL of 0.01 N aqueous nitric acid, and subjected to atomic absorption analysis. The boron compound content in terms of boron compound was obtained.

[7] Moisture content of heat-sealable layer Determined by weight measurement method. When the film for heat sealing described in each Example and Comparative Example is a single layer film, the mass when cut out to 200 × 200 mm is (Wc), and then heated in a hot air dryer at 120 ° C. for 2 hours. The subsequent mass was (Wd), and the moisture content of the heat-sealing layer was determined by the following formula. When the heat-sealing film described in each example and comparative example was a multilayer film, the heat-sealing layer was peeled to form a single-layer film of the heat-sealing layer, and the moisture content was determined in the same manner as described above.
Moisture content (wt%) = {Wc−Wd} ÷ Wd × 100

[8] Equilibrium moisture content of heat-sealing layer The equilibrium moisture content in the heat-sealing layer of the heat sealing film described in each example and comparative example is 8.3 “equilibrium moisture content” of JIS-L1015-2010. It calculated | required based on the measuring method. In the case of a single-layer film, the entire film was obtained. In the case of a multilayer film, the heat-sealed layer was peeled off to form a single-layer film having a heat-fused layer, and the equilibrium moisture content was determined.

[9] Half-value width of endothermic peak indicating melting in differential scanning calorimetry. It was determined by differential scanning calorimetry. That is, the differential scanning calorimetry (at the rate of temperature increase of 10 ° C./min from 30 ° C. to 300 ° C. in accordance with JIS-K7121 for the heat sealing layer of the heat sealing film described in each example and comparative example ( The differential scanning calorimeter (DSC) RDC220 / SSC5200H type manufactured by Seiko Denshi Kogyo Co., Ltd. was used, and in the graph of the DSC curve (defined by the above JIS) with the temperature on the horizontal axis, melting of EVOH in the heat-sealing layer When the difference between the peak of the endothermic peak and the baseline is A, the two temperatures at which the difference from the baseline is (A / 2) before and after the peak of the endothermic peak are calculated and the difference is calculated. Obtained.

[10] Density of heat-sealing layer It was determined with a density gradient tube. That is, the density of the heat-sealing layer of the heat-sealing film described in each example and comparative example was 5 mm × using a density gradient tube filled with an n-hexane / carbon tetrachloride mixed liquid kept at 25 ° C. The density of a 5 mm film-like sample was measured. In the case of a single layer, the entire film was obtained. In the case of a multilayer film, the heat-sealed layer was peeled to form a single-layer film of the heat-fused layer, and the density was determined.

[Example 1]
Ethylene content 48 mol%, saponification degree 99.9 mol% or more, solubility parameter (SP value) 12.0 (cal / cm ³ ) ^1/2 , melting point 160.0 ° C., terminal carboxylic acid unit and lactone ring An EVOH resin pellet containing EVOH having a unit content of 0.17 mol%, having a metal (alkali metal and alkaline earth metal) salt content of 80 ppm and a boron compound content of 500 ppm is simply used with a T die having a die width of 450 mm. A film was formed to obtain a heat seal film (thickness 30 μm) of Example 1 having a moisture content of 0.2% by mass.

The obtained heat sealing film (heat-sealing layer) has a metal (alkali metal and alkaline earth metal) salt content of 80 ppm and a boron compound content of 500 ppm, and has an equilibrium moisture content at a temperature of 23 ° C. and a relative humidity of 50%. Is 1.9% by mass, and the half-value width of the endothermic peak indicating melting of EVOH in differential scanning calorimetry (DSC) measured at a heating rate of 10 ° C./min from 30 ° C. to 300 ° C. is 11.1 ° C. And the density was 1.12 g / cm ³ .

[Example 2]
Ethylene content 44 mol%, saponification degree 99.9 mol% or more, solubility parameter (SP value) 12.2 (cal / cm ³ ) ^1/2 , melting point 165.0 ° C., terminal carboxylic acid unit and lactone ring 80 parts by mass of EVOH resin pellets containing EVOH having a unit content of 0.17 mol%, a metal (alkali metal and alkaline earth metal) salt content of 105 ppm and a boron compound content of 1,400 ppm, and adhesive high density polyethylene (Mitsubishi Chemical Co., Ltd. “Modic H511”) 20 parts by mass was dry blended, a single layer was formed using a T-die having a die width of 450 mm, and the heat seal of Example 2 having a moisture content of 0.2% by mass Film (thickness 30 μm) was obtained.

The obtained heat sealing film (heat-sealed layer) had a metal (alkali metal and alkaline earth metal) salt content of 84 ppm and a boron compound content of 1120 ppm, an equilibrium moisture content at a temperature of 23 ° C. and a relative humidity of 50%. Is 2.0% by mass, and the half-value width of the endothermic peak indicating melting of EVOH in differential scanning calorimetry (DSC) measured at a heating rate of 10 ° C./min from 30 ° C. to 300 ° C. is 8.5 ° C. And the density was 1.10 g / cm ³ .

[Examples 3-15, 17 and 18 and Comparative Examples 1-5]
Except that the physical properties described above are the physical properties described in Table 1, the heat seal films of Examples 3 to 15, 17 and 18 and Comparative Examples 1 to 5 (thickness 30 μm) are the same as in Example 1. Manufactured. In Table 1, “-” indicates that measurement was not performed. In addition, the moisture content shall have a different value by preserve | storing each obtained film for 7 days in the predetermined environment where humidity and temperature differ.

  In Example 18, the EVOH resin pellets used in Example 5 and nylon ("UBE nylon-1022FDX23" manufactured by Ube Industries, Ltd.) were co-extruded to form a two-layer film (each layer has a thickness of 30 μm). . In Comparative Example 1, polyethylene was used as the resin, and in Comparative Example 5, polyvinyl alcohol was used as the resin.

[Example 16]
Ethylene content 32 mol%, saponification degree 99.9 mol% or more, solubility parameter (SP value) 13.0 (cal / cm ³ ) ^1/2 , melting point 183.0 ° C., terminal carboxylic acid unit and lactone ring EVOH resin pellets containing EVOH having a unit content of 0.18 mol%, a metal (alkali metal and alkaline earth metal) salt content of 205 ppm, and a boron compound content of 400 ppm were simply added using a T die having a die width of 450 mm. After film formation, a heat seal film (thickness 20 μm) of Example 16 having a water content of 0.3 mass% was stretched 3 times in the longitudinal direction and 3 times in the lateral direction by a tenter stretching machine.

The obtained heat sealing film (heat-sealed layer) has a metal (alkali metal and alkaline earth metal) salt content of 205 ppm and a boron compound content of 400 ppm, and has an equilibrium moisture content at a temperature of 23 ° C. and a relative humidity of 50%. Is 3.0% by mass, and the half-value width of the endothermic peak indicating the melting of EVOH in differential scanning calorimetry (DSC) measured at a heating rate of 10 ° C./min from 30 ° C. to 300 ° C. is 6.0 ° C. And the density was 1.19 g / cm ³ .

[Evaluation]
(Heat sealability)
The obtained heat sealing films were superposed and pressure-bonded for 1 second under the conditions of a temperature of 185 ° C. and a pressure of 0.1 MPa using a hot plate heat sealer (bag sealer HBS-280 manufactured by Hirai Shoji Co., Ltd.). In addition, in the heat sealing film of Example 18, the heat sealing layers were overlapped and performed in the same manner.

  The heat seal strength (N / 15 mm) per 15 mm width of the heat-sealed film was measured with a tensile tester. The tensile speed at the time of measuring the seal strength was 300 mm / min. The results are shown in Table 1.

Further, the appearance of the heat-sealed portion was visually evaluated according to the following criteria.
○: Excellent appearance △: Slight thinning and foaming occur and appearance is slightly bad ×: Appearance is poor, such as thinning and foaming are conspicuous

(Non-sorption property of scent component)
Each obtained film was cut into a 10 cm square and left in a 500 mL glass bottle to which 0.1 mL of d-limonene was added. The gas phase part in the glass bottle was set to a temperature of 23 ° C. and a relative humidity of 50%. Two samples were prepared with the films of each Example and Comparative Example, and the films were taken out after 1 hour and 1 week, washed with water, and then subjected to sensory evaluation by 10 subjects. Five-stage evaluation of 1 to 5 was performed, assuming that the intensity of the fragrance remaining on the film was weaker. The average value of 10 people was taken, and the numbers after the decimal point were rounded off. In each of the standing times, since the strongest odor was rated as 5 and the weakest odor as 1 relative, the odor intensity corresponding to, for example, evaluation “3” after 1 hour and 1 week. Is different. Here, it is considered that the non-sorption property after 1 hour depends on the moisture content at the time of processing (during heat sealing), and the non-sorption property after 1 week depends on the equilibrium moisture content.

  As shown from the results in Table 1, it is shown that the heat sealing films of Examples 1 to 18 are excellent in heat sealing properties and non-sorption properties of scent components.

  As described above, the heat sealing film of the present invention is excellent in the non-sorption property of the scent component, and therefore can be suitably used as a film for packaging bags for foods, fragrances, and luxury items.

Claims (13)

The outermost layer includes a heat-sealing layer containing an ethylene-vinyl alcohol copolymer,
The ethylene content of the ethylene-vinyl alcohol copolymer is 20 mol% or more and 70 mol% or less, the saponification degree is 90 mol% or more,
Temperature 23 ° C. above the heat sealable layer, the equilibrium moisture content at a relative humidity of 50% Ri der 0.5 mass% to 5.0 mass%,
The ethylene-vinyl alcohol copolymer has a terminal carboxylic acid unit and a lactone ring unit,
Ethylene units, vinyl alcohol units and the carboxylic acid unit and the total amount for the heat-sealing Ru der 0.30 mol% 0.05 mol% film lactone ring unit to the total amount of the vinyl ester units. Having a layer structure of two or more layers,
The heat sealing film according to claim 1, wherein at least one outermost layer is composed of the heat fusion layer.   The heat sealing film according to claim 1 or 2, wherein the moisture content of the heat-sealing layer is 0.1 mass% or more and 4.0 mass% or less.   In the differential scanning calorimetry in which the heat-sealable layer was measured at a heating rate of 10 ° C./min from 30 ° C. to 300 ° C., the half-value width of the endothermic peak indicating the melting of the ethylene-vinyl alcohol copolymer was 5. The film for heat sealing according to claim 1, wherein the film is 0 ° C. or higher and 20.0 ° C. or lower. The ethylene-vinyl alcohol copolymer has a solubility parameter (SP value) of 11.0 or more and a melting point of 170 ° C. or less.
The heat sealing film according to any one of claims 1 to 4, wherein the heat-sealing layer has a density of 1.10 g / cm ³ or more and a thickness of 2 µm to 100 µm. The heat sealing layer contains a metal salt;
The heat sealing film according to any one of claims 1 to 5 , wherein the content of the metal salt in the heat-fusible layer is 1 ppm or more and 10,000 ppm or less in terms of a metal element. The heat fusion layer contains a boron compound,
The film for heat sealing according to any one of claims 1 to 6 , wherein the content of the boron compound in the heat-fusible layer is 50 ppm or more and 2,000 ppm or less. Heat sealing film according to any one of claims 1 to 7 which is used for packaging bag. Is opposed to the thermal adhesion layer between a temperature 185 ° C. using a hot plate type heat sealer to claim 8 strength of the heat seal is 10 N / 15 mm or more which is obtained by bonding 1 second under a pressure of 0.1MPa The film for heat sealing as described. A packaging bag formed from the heat-sealing film according to claim 8 or 9 , wherein the heat-sealing layer of the heat-sealing film is the inside, and the heat-sealing layer is heat-sealed. The packaging bag according to claim 10 , wherein a moisture content of the heat-sealing layer at the time of heat sealing is 0.1 mass% or more and 4.0 mass% or less. The packaging bag according to claim 10 or 11 , which has a zipper. The packaging bag according to claim 10 , 11 or 12 , wherein the content to be packaged is at least one selected from the group consisting of confectionery, tea leaves, coffee, spices and tobacco.