JP2009154527A - Heat-sealable film and its forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat-sealable film having a cellophane film as a base and having high heat sealing performance and dam-proofing (water vapor barrier properties), and also to provide a forming method of the same. <P>SOLUTION: The heat-sealable film is obtained by forming, at least on one side of the cellophane film, a heat-sealing layer containing 1-12 pts.wt. curatives (poly isocyanate etc.) and 2-25 pts.wt. plasticizer of a low molecular weight, relative to 100 pts.wt. a vinyl chloride-acetic acid vinyl based copolymer whose vinyl chloride content is ≥80 wt.% and an isolated acetic acid vinyl content is ≤0.1 wt.%. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a heat-sealable film excellent in low-temperature sealability and useful as a packaging material for foods and the like, and a method for producing the same.

  Films for packaging such as foods and pharmaceuticals usually require heat sealability in addition to barrier properties against oxygen, water vapor and the like. As such a packaging film, for example, a coating agent (vinylidene chloride resin or polyvinyl alcohol resin) containing a resin having a high gas barrier property is applied to a biaxially stretched polyethylene terephthalate film or a biaxially stretched polypropylene film to form a gas barrier. A gas barrier film in which a layer is formed is known. However, such a gas barrier layer is inferior in heat sealability.

  Cellophane films having a relatively high oxygen gas barrier property are also used as packaging films. However, since the cellophane film does not have a water vapor barrier property and a heat seal property, it is necessary to impart a heat seal property together with the water vapor barrier property in order to form a package.

  JP-A-4-334442 (Patent Document 1) discloses a coated film in which one surface of a base film is coated with a heat seal layer and the other surface is coated with an oil-resistant layer. This document describes that the heat seal layer may be formed of a vinyl chloride-vinyl acetate copolymer, but the heat seal layer may be formed of a vinylidene chloride copolymer such as vinylidene chloride-methyl acrylate. Preferred is described.

  In JP-A-5-42640 (Patent Document 2), a coating containing a vinyl acetate-vinyl chloride copolymer having a vinyl chloride content of 70 to 90% by weight and an average polymerization degree of 350 or more on one surface of a base film. It describes that a liquid is applied to produce a heat-sealable film.

JP-A-8-336927 (Patent Document 3) discloses a barrier composite film in which an inorganic thin film layer is formed on at least one surface of a base film via an anchor coat layer. , (A) 10 to 500 parts by weight of a polyisocyanate compound, (C) a glass transition temperature of -10 to 20 ° C. and several parts per 100 parts by weight of a chlorine-containing resin such as a vinyl chloride-vinyl acetate copolymer. It is also described that it is formed of a coating agent having an average molecular weight of 1 × 10 ^{4 to} 5 × 10 ⁴ and containing 1 to 50 parts by weight of a saturated polyester resin that is substantially non-reactive with the polyisocyanate compound. . In Patent Document 1, as a vinyl chloride-vinyl acetate copolymer, a vinyl chloride-vinyl acetate-maleic anhydride copolymer (chlorine content 48.8%, average polymerization degree 430, glass transition temperature 43 ° C., Acid value caused by maleic anhydride is about 10 mgKOH / g), polyester resin mainly composed of terephthalic acid and ethylene glycol as saturated polyester resin (number average molecular weight 22,000, glass transition temperature 7 ° C., hydroxyl value 4.8 mgKOH) Examples using / g) are also described. Furthermore, it is described that a gas barrier resin layer or a heat seal layer may be formed on the inorganic thin film layer.

However, when the anchor coat layer is applied to a cellophane film, the heat sealability at a temperature of 100 ° C. or lower is inferior to the adhesiveness. Therefore, it is also difficult to impart high moisture resistance to the cellophane film and its package.
JP-A-4-334442 ([Claims], paragraph [0016]) JP-A-5-42640 ([Claims], paragraph [0024]) JP-A-8-336927 ([Claims], paragraph [0041], [Example])

  Therefore, the objective of this invention is providing the heat-sealable film to which the outstanding heat-seal property was provided with respect to the cellophane film, and its manufacturing method.

  Another object of the present invention is to provide a heat-sealable film having an excellent heat-seal layer and adhesion, and having excellent moisture resistance (water vapor barrier property) and a method for producing the same.

  As a result of intensive studies to achieve the above-mentioned problems, the inventor has obtained a predetermined coating containing a cellophane film containing a predetermined chlorine-containing resin, a curing agent (such as polyisocyanate), and a plasticizer (such as an aliphatic plasticizer). It was found that when applied with an agent, the cellophane film can be provided with excellent heat-sealability and also improved in moisture resistance (water vapor barrier property), and the present invention has been completed.

  That is, the heat-sealable film of the present invention has a vinyl chloride-vinyl acetate copolymer, a curing agent (such as polyisocyanate), and a plasticizer (such as an aliphatic plasticizer) on at least one surface of the cellophane film. A heat seal layer is formed.

The vinyl chloride-vinyl acetate copolymer is a copolymer of vinyl chloride, vinyl acetate, and a monomer having a carboxyl group or an acid anhydride group (for example, vinyl chloride-vinyl acetate-maleic acid copolymer). Merging). The vinyl chloride-vinyl acetate copolymer may have a vinyl chloride content of 80% by weight or more. Further, the heat seal layer may be formed of a coating agent containing a vinyl chloride-vinyl acetate copolymer having a free vinyl acetate content of 0.1% by weight or less. The curing agent may be a polyisocyanate, and the polyisocyanate may have 3 or more isocyanate groups. The plasticizer may be an aliphatic plasticizer. Plasticizers include citrate plasticizers, C _6-10 aliphatic dicarboxylic acid diC _4-12 alkyl ester plasticizers (adipic acid plasticizers, azelaic acid plasticizers, sebacic acid plasticizers, etc. ), it may be an polyester plasticizer, polyester _plasticizer, a _{C 2-6} alkane _diol, polymers of _{C 4-10} alkane dicarboxylic acid or a reactive derivative _thereof; a _{C 4-10} lactone Polymer: at least one selected from polymers of C _2-6 alkanediol, C _4-10 alkanedicarboxylic acid or a reactive derivative thereof, and C _4-10 lactone (for example, C _2-6 alkanediol and Polymer with adipic acid). Further, the plasticizer may have a low molecular weight, and the number average molecular weight of the plasticizer may be about 200 to 3500 (for example, 300 to 3000). The ratio of each component which forms the said heat seal layer is 1-12 weight part of hardening | curing agents (polyisocyanate etc.) with respect to 100 weight part of vinyl chloride-vinyl acetate type copolymers, and 2-25 weight of plasticizers, for example. The coating agent containing such components may be formed. The heat-sealable film of the present invention is excellent in water vapor barrier property and heat seal property. For example, the water vapor barrier property is 300 g / m ² · MPa · day or less, and the heat seal layers are adhered to each other at a temperature of 90 ° C. The heat seal strength may be 800 mN / 15 mm or more.

  The present invention forms a heat seal layer containing a vinyl chloride-vinyl acetate copolymer, a curing agent (such as polyisocyanate) and a plasticizer (such as an aliphatic plasticizer) on at least one surface of a cellophane film. The manufacturing method of a heat-sealable film is also included.

  In this invention, since the heat seal layer comprised by the predetermined component is formed in the surface of a cellophane film, the heat seal property excellent in the cellophane film can be provided. Moreover, it has excellent adhesiveness and is excellent in moisture resistance (water vapor barrier property). Furthermore, in this invention, the heat-sealable film which has the said characteristic can be manufactured by simple operation called application | coating.

  The heat sealable film of the present invention comprises a cellophane film as a substrate and a heat seal layer formed on at least one surface of the cellophane film, and the heat seal layer comprises vinyl chloride-vinyl acetate. A copolymer, a curing agent (such as polyisocyanate), and a plasticizer.

  In the present specification, the “cellophane film” means a film having at least a cellophane layer on the surface (or a cellophane surface exposed on the surface). Accordingly, the cellophane film may be a single-layer film or a laminated film in which one surface of the cellophane layer is coated as long as it has a cellophane layer on at least the surface. Therefore, the heat-sealable film of the present invention comprises a base film having at least a cellophane layer on at least one surface and a heat seal layer formed on at least one cellophane surface of the base film. I can also say.

  In the laminated film, the layer laminated with the cellophane layer may be, for example, an olefin resin film [eg, polypropylene resin (polypropylene, propylene-ethylene copolymer, etc.); polyethylene resin (low density polyethylene, linear low density). Polyethylene, medium density polyethylene, high density polyethylene, etc.); olefin resin film such as cyclic polyolefin resin], styrene resin film (eg, styrene resin film such as polystyrene film, styrene-methyl methacrylate copolymer), Vinyl alcohol resin films (vinyl alcohol resin films such as polyvinyl alcohol and ethylene-vinyl alcohol copolymers), polyester resin films (aliphatic polyesters such as polybutylene adipate; Polyalkylene arylates such as reethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; aromatic polyester-based resin films such as polyarylate), polyamide-based resin films (aliphatic polyamides such as polyamide 6, polyamide 66, polyamide 611, and polyamide 612); Polyamide resin films such as alicyclic polyamides), cellulose ester resin films (cellulose ester resin films such as cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose acetate propionate, and cellulose acetate butyrate). Examples thereof include resin films; metal foils such as aluminum foil; paper; or composite films in which these layers are laminated.

  Furthermore, the cellophane film may be a laminated film in which a barrier layer is formed on one surface of the cellophane layer directly or via an adhesive layer. The barrier layer is a resin having excellent oxygen barrier properties (for example, vinylidene chloride copolymer, ethylene-vinyl alcohol copolymer, polyvinyl alcohol polymer), or a resin having high water vapor barrier properties (for example, vinylidene chloride copolymer). ).

  The cellophane film may be unstretched or may be uniaxially or biaxially stretched. The laminated film may be prepared by adhering a layer such as the resin film with an adhesive on one surface of the cellophane layer, or by adhering by a method such as melt lamination without using an adhesive. May be. The laminated film can be prepared by a method of laminating a barrier resin on one surface of the cellophane layer, a method of applying a coating agent containing the barrier resin, or the like.

  As the cellophane film, a cellophane monolayer film is usually used in many cases.

  The thickness of the cellophane film can be selected, for example, from the range of about 3 to 100 μm, and may usually be about 5 to 50 μm, preferably 10 to 45 μm, and more preferably about 15 to 45 μm (for example, 20 to 40 μm). If necessary, the surface of the cellophane film may be subjected to surface treatment (for example, corona discharge treatment).

  The heat seal layer may cover at least one surface (cellophane surface) of the cellophane film via an intermediate layer such as a primer layer, an anchor coat layer, or an adhesive. Usually, the cellophane surface is directly coated. There are many.

The vinyl chloride-vinyl acetate copolymer of the heat seal layer may be a copolymer having vinyl chloride and vinyl acetate as a polymerizable monomer, and further includes vinyl chloride, vinyl acetate and a copolymerizable monomer. The copolymer may be used. Examples of the copolymerizable monomer include olefins (such as α-C _2-6 olefins such as ethylene, propylene, and butene), (meth) acrylic monomers [methyl (meth) acrylate, (meth ) (Meth) acrylic acid alkyl esters such as ethyl acrylate, butyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate; (meth) acrylic acid 2 -Hydroxyethyl, (meth) acrylic acid hydroxyalkyl ester such as 2-hydroxypropyl (meth) acrylate; (meth) acrylic acid glycidyl ester, etc.], polymerizable monomer having a carboxyl group or an acid anhydride group [( Meth) acrylic acid, maleic acid, fumaric acid, maleic anhydride, itaconic acid, etc.] These copolymerizable monomers can be used alone or in combination of two or more. Preferred copolymerizable monomers are (meth) acrylic monomers, polymerizable monomers having a carboxyl group or an acid anhydride group [for example, (meth) acrylic acid, maleic acid, maleic anhydride, etc.]. is there. In the vinyl chloride-vinyl acetate copolymer, a part of vinyl acetate units may be converted to vinyl alcohol units by hydrolysis.

  Preferred vinyl chloride-vinyl acetate copolymers include vinyl chloride-vinyl acetate copolymers, vinyl chloride and vinyl acetate and copolymerizable monomers [(meth) acrylic acid, maleic acid, maleic anhydride, etc.]. It is a copolymer. Examples of the latter copolymer include vinyl chloride-vinyl acetate-maleic acid copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, vinyl chloride-vinyl acetate- (meth) acrylic acid copolymer, etc. it can. Particularly preferred vinyl chloride-vinyl acetate copolymers are vinyl chloride-vinyl acetate-maleic acid copolymer and vinyl chloride-vinyl acetate-maleic anhydride copolymer. Such a copolymer can greatly improve the adhesion to cellophane.

  In the vinyl chloride-vinyl acetate copolymer, the ratio of vinyl chloride to vinyl acetate is, for example, vinyl chloride / vinyl acetate (weight ratio) = 98/2 to 50/50, preferably 97/3 to 65/35. More preferably, it is often selected from the range of about 95/5 to 75/25. In the vinyl chloride-vinyl acetate copolymer, the vinyl chloride content may be large, for example, vinyl chloride / vinyl acetate (weight ratio) = 97 / 3-80 / 20, preferably 95 / 5-83 / 17. (For example, about 93/7 to 85/15). The ratio of the total amount of vinyl chloride and vinyl acetate to the copolymerizable monomer is the former / the latter (weight ratio) = 99.9 / 0.1 to 85/15, preferably 99.5 / 0.5 to 90. / 10, more preferably about 99/1 to 95/5. In the present invention, the vinyl chloride content is 80% by weight or more (for example, 80 to 98% by weight), preferably 83 to 95% by weight, more preferably 85 to 93% by weight (for example 85 to 90% by weight). A vinyl chloride-vinyl acetate copolymer is often used. Usually, even if such a copolymer is used as it is, the adhesiveness with the cellophane film and the heat sealing property at a temperature of 100 ° C. or less between the coating layers do not appear. However, by combining a copolymer with a vinyl chloride content of 80% by weight or more with the curing agent (polyisocyanate, etc.) and a plasticizer, a heat seal layer can be laminated on the cellophane surface with high adhesion, and an excellent heat Sealability and water vapor barrier properties can be imparted. Moreover, as will be described later, such a vinyl chloride-vinyl acetate copolymer is preferable from the viewpoint of the working environment because it often has a low free vinyl acetate content.

A vinyl chloride-vinyl acetate copolymer is generally substantially non-reactive with a curing agent (such as polyisocyanate). That is, the concentration of active hydrogen atoms is low even if the vinyl chloride-vinyl acetate copolymer is non-reactive with a curing agent (polyisocyanate, etc.) or has reactive active hydrogen atoms. It is. The acid value of the vinyl chloride-vinyl acetate copolymer is, for example, about 0 to 30 mgKOH / g, preferably about 0 to 20 mgKOH / g. In addition, the glass transition temperature of the said vinyl chloride-vinyl acetate type copolymer is 50-85 degreeC (for example, 60-83 degreeC), for example, Preferably it is about 65-80 degreeC (for example, 70-80 degreeC). There are many cases. The molecular weight of the vinyl chloride-vinyl acetate copolymer is, for example, a number average molecular weight of 0.5 × 10 ⁴ to 10 × 10 ⁴ , preferably 0.7 × 10 ^{4 to} 7 × 10 ⁴ , and more preferably 1 × 10. It is about ^{4 to} 5 × 10 ⁴ .

  In the vinyl chloride-vinyl acetate copolymer, the free vinyl acetate content is 0.1 wt% or less (for example, 0 to 700 ppm, industrially 5 to 500 ppm, preferably 10 to 300 ppm, more preferably 20 to 250 ppm). Such vinyl chloride-vinyl acetate copolymers often have a vinyl chloride content of 80% by weight or more. Further, the vinyl chloride-vinyl acetate copolymer is often marketed in a solid form (for example, a form such as a pellet or a resin powder). When such a vinyl chloride-vinyl acetate copolymer is used, no odor is generated in the production process of the heat-sealable film. In order to secure adhesion to the cellophane film and heat sealability at a temperature of 100 ° C. or less, vinyl chloride-vinyl acetate having a vinyl acetate content of 25 to 40% by weight and an average molecular weight of 8,000 to 40,000. It is advantageous to use a system copolymer (such as vinyl chloride-vinyl acetate-maleic acid copolymer). Such a copolymer is commercially available in the form of a solution dissolved in an organic solvent (such as ethyl acetate). However, because such a vinyl-vinyl acetate copolymer is prepared by a solution polymerization method, the free vinyl acetate content is as high as about 6 to 8% by weight, and an odor is generated in the coating process. It is not preferable in terms of the working environment.

  As the curing agent, various curing agents or crosslinking agents that can improve the adhesion of the heat seal layer can be used, and such curing agents include polyisocyanate and the like. Examples of the polyisocyanate include tolylene diisocyanate, phenylene diisocyanate, xylylene diisocyanate, tetramethylxylene diisocyanate, diphenylalkane diisocyanate [diphenylmethane diisocyanate, bis (4-isocyanate-3-methylphenyl) methane, 2,2-bis ( 4-isocyanatophenyl) propane], aromatic diisocyanates such as triphenylmethane triisocyanate, 1,5-naphthalene diisocyanate; 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, 1, 10-decamethylene diisocyanate, lysine diisocyanate, 1,3,6-hexamethylene triisocyanate Aliphatic diisocyanates such as over preparative; isophorone diisocyanate, hydrogenated xylylene diisocyanate, alicyclic diisocyanates such as hydrogenated diphenylmethane diisocyanate; modified products of polyisocyanates and the like are exemplified. Examples of the modified polyisocyanate include adducts and dimers obtained by adding polyisocyanates to polyhydric alcohols (for example, triols such as glycerin, trimethylolpropane and trimethylolethane, and tetraols such as pentaerythritol). , A trimer having an isocyanurate ring, an allophanate-modified product, a urea-modified polyisocyanate, a burette-modified polyisocyanate, and the like. These polyisocyanates can be used alone or in combination of two or more.

  Preferred polyisocyanates include low molecular weight compounds having 3 or more isocyanate groups in the molecule, for example, adducts in which 3 moles of polyisocyanate (diisocyanate such as tolylene diisocyanate and hexamethylene diisocyanate) are added to 1 mole of trimethylolpropane, Examples include trimers of diisocyanates having an isocyanurate ring, prepolymers, and the like. Furthermore, the molecular weight (or number average molecular weight) of the polyisocyanate can be selected from the range of about 150 to 1000, preferably about 300 to 1000, for example.

Even if it is a phthalate plasticizer (phthalic acid C _1-12 alkyl ester, etc.), heat sealability is effectively expressed, but from the viewpoint of safety and hygiene, the plasticizer is a non-phthalate ester plasticizer. Preferably there is. Examples of the plasticizer include aliphatic plasticizers (aliphatic polycarboxylic acid alkyl esters, polyhydric alcohol fatty acid esters (triacetin, etc.), polyester components, etc.), trimellitic ester plasticizers (trioctyl trimellitic acid, etc.) _Trimellitic acid C _4-16 alkyl ester, etc.), phosphate ester plasticizer (triaryl phosphate such as triphenyl phosphate, tricresyl phosphate; tributyl phosphate, trioctyl phosphate, tri (2-ethylhexyl) phosphate, etc. Examples thereof include trialkyl phosphates) and epoxy derivatives (epoxidized soybean oil, epoxidized linseed oil, etc.). These plasticizers can be used alone or in combination of two or more.

Preferred plasticizers are aliphatic plasticizers, particularly aliphatic polyvalent carboxylic acid alkyl esters and polyester components (or polyester plasticizers). Examples of the aliphatic polycarboxylic acid alkyl ester include hydroxypolycarboxylic acid plasticizers and aliphatic dicarboxylic acid plasticizers. Typical hydroxypolycarboxylic acid plasticizers include citrate ester plasticizers (tri-C _4-12 alkyl citrates such as tributyl acetyl citrate, trioctyl acetyl citrate, tri (2-ethylhexyl) citrate). Ester) and the like. Examples of the aliphatic dicarboxylic acid plasticizer include C _4-12 aliphatic dicarboxylic acid diC _2-12 alkyl esters such as adipic acid plasticizer (dibutyl adipate, dioctyl adipate, di (2-ethylhexyl) adipate, diisodecyl adipate and adipate C _4-12 alkyl esters such as diisononyl adipate), azelaic acid plasticizer (dibutyl azelate, dioctyl azelate, di (2-ethylhexyl) azelate, azelate such as diisodecyl azelate C _{4- 12} such as an alkyl ester), sebacate plasticizers (dibutyl sebacate, dioctyl sebacate, di (2-ethylhexyl) sebacate, sebacic acid di C _4-12 alkyl esters such as diisodecyl sebacate), these alkyl Pimelic acid dialkyl ester corresponding to the ester, such as suberic acid dialkyl ester can be exemplified.

Reactive components (monomers) that form aliphatic polyester components (or polyester plasticizers) include diols and dicarboxylic acids (dicarboxylic acids or reactive derivatives thereof); lactones; and oxycarboxylic acids or reactions thereof Diols and dicarboxylic acids may be combined with lactones and / or oxycarboxylic acids. In addition, the reactive derivative of dicarboxylic acid includes an acid anhydride, an acid halide (acid chloride, etc.), a lower alkyl ester (C _1-2 alkyl ester, etc.), and the reactive derivative of oxycarboxylic acid includes Acid halides (such as acid chlorides), lower alkyl esters (such as _C1-2 alkyl esters) and the like are included.

Diols include aliphatic diols (chain diols) such as ethylene glycol, propylene glycol, trimethylene glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6 -C _2-10 alkane diols such as hexanediol and neopentyl glycol; polyoxy C _2-4 alkylene glycols such as diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, and polytetramethylene ether glycol. These diols can be used alone or in combination of two or more. Of these diols, C _2-6 alkanediol (particularly C _2-4 alkanediol) is often used.

Dicarboxylic acids include aliphatic dicarboxylic acids (chain dicarboxylic acids), for example, C _4-16 alkanedicarboxylic acids such as succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, and the like. And reactive derivatives. These dicarboxylic acids can be used alone or in combination of two or more. Of these dicarboxylic acids, saturated C _4-10 alkane dicarboxylic acids (particularly C _4-6 alkane dicarboxylic acids) such as adipic acid, azelaic acid and sebacic acid or reactive derivatives thereof are often used.

Examples of lactones include C _3-10 lactones such as propiolactone, butyrolactone, valerolactone, ε-caprolactone, and laurolactone; dimers of hydroxycarboxylic acids such as C _4-10 cyclics such as glycolide and lactide. Examples include diesters. These lactones can be used alone or in combination of two or more. Preferred lactones are C _4-8 lactones (particularly C _4-6 lactones such as ε-caprolactone).

Examples of oxycarboxylic acids include hydroxy C _2-10 alkanecarboxylic acids such as glycolic acid, lactic acid, β-oxypropionic acid, and α-oxybutyric acid. Hydroxycarboxylic acids may be used alone or in combination of two or more. Among these hydroxycarboxylic acids, α-hydroxy C _2-6 alkane carboxylic acid, particularly α-hydroxy C _2-4 alkane carboxylic acid (such as lactic acid) is used.

  If necessary, alicyclic components (cyclohexanediol, cyclohexanedimethanol, alicyclic diols such as hydrogenated bisphenol A, alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid, etc.), aromatic components (bisphenols and Aromatic polyhydric alcohols such as adducts with alkylene oxides, aromatic dicarboxylic acids such as terephthalic acid and isophthalic acid, aromatic hydroxycarboxylic acids such as hydroxybenzoic acid and hydroxynaphthoic acid, etc.), polyfunctional monomers ( Glycerin, trimethylolethane, trimethylolpropane, polyols such as pentaerythritol, polyvalent carboxylic acids such as pyromellitic acid, etc.) may be used. Moreover, in order to block the remaining hydroxyl group or carboxyl group, a monohydric alcohol, monocarboxylic acid, or the like may be used as a terminal blocking agent.

The aliphatic polyester component (or polyester plasticizer) is a polymer obtained by a condensation reaction between a diol and a dicarboxylic acid or a reactive derivative thereof, a polymer of a lactone, a polymer of an oxycarboxylic acid, a diol and a dicarboxylic acid or its It may be a polymer of a reactive derivative and a reaction component selected from lactones and oxycarboxylic acids, or a polymer of lactones and oxycarboxylic acids. A preferred aliphatic polyester component (or polyester plasticizer) is a polymer of C _2-6 alkanediol and C _4-10 alkanedicarboxylic acid or a reactive derivative thereof [poly (alkylene adipate), poly (alkylene azela]. Ate), poly (alkylene sebacate), etc.]; C _4-10 lactone polymer (polycaprolactone, etc.); C _2-6 alkanediol, C _4-10 alkanedicarboxylic acid or a reactive derivative thereof, and C _{4 It} may be a polymer with _-10 lactone [poly (alkylene adipate) -caprolactone graft copolymer, etc.]. The aliphatic polyester component (or polyester plasticizer) is often a polymer of C _2-6 alkanediol and C _4-10 alkane dicarboxylic acid or a reactive derivative thereof.

  The aliphatic polyester component may be an unsaturated polyester, but is usually a saturated polyester. In addition, the aliphatic polyester component may be crystalline, but is usually amorphous in many cases.

These aliphatic plasticizers can be used alone or in combination of two or more. Preferred plasticizers include citrate plasticizers, aliphatic dicarboxylic acid dialkyl ester plasticizers (C _6-10 aliphatic dicarboxylic acid diplastics such as adipic acid plasticizers, azelaic acid plasticizers, sebacic acid plasticizers, etc. C _4-12 alkyl ester), aliphatic polyester component [polymer of C _2-6 alkanediol and C _6-10 alkanedicarboxylic acid such as adipic acid or a reactive derivative thereof (poly (1,3-butylene adipate) Poly (C _2-6 alkylene adipate) and the like)]. In order to suppress bleed-out or migration of the plasticizer from the heat seal layer, an aliphatic polyester component (polyester plasticizer) is advantageous.

  The plasticizer may be substantially non-reactive with a curing agent (polyisocyanate or the like), like the vinyl chloride-vinyl acetate copolymer. The OH value of a plasticizer (such as an aliphatic polyester component) is, for example, 0 to 15 mgKOH / g, preferably about 0 to 10 mgKOH / g, and often about 0 to 5 mgKOH / g. The acid value of the plasticizer (such as an aliphatic polyester component) is, for example, 0 to 10 mgKOH / g, preferably about 0 to 7 mgKOH / g, and often about 0 to 5 mgKOH / g.

  The plasticizer may be a solid at room temperature (15 to 25 ° C.), but may be a viscous liquid or a liquid. The glass transition temperature of the plasticizer is, for example, about −80 ° C. to 20 ° C., preferably about −60 ° C. to 15 ° C. (eg, −50 ° C. to 15 ° C.), and may be about −30 ° C. to 20 ° C. Many.

A plasticizer (such as an aliphatic polyester component) is an aliphatic polyester plastic having a relatively high molecular weight (for example, a number average molecular weight of 3 × 10 ^{4 to} 20 × 10 ⁴ ) in gel permeation chromatography (reference polymer: polystyrene). The molecular weight of the plasticizer (such as an aliphatic polyester component) may be a number average molecular weight of about 0.1 × 10 ⁴ to 1 × 10 ⁴ . The molecular weight of a plasticizer (such as an aliphatic polyester component) is often a relatively low molecular weight (molecular weight of the oligomer region) (for example, a number average molecular weight of 200 to 5000, preferably about 250 to 4000). The molecular weight of the relatively low molecular weight plasticizer may be, for example, about a number average molecular weight of 200 to 3500 (eg, 250 to 3000), and is usually 300 to 3500 (eg, 350 to 3200), preferably 400 to It is about 3000 (for example, 400-2500). In addition, the number average molecular weight of a low molecular weight plasticizer (for example, adipic acid plasticizer etc.) can be calculated based on the chemical formula of a plasticizer.

  The heat seal layer can be composed of a vinyl chloride-vinyl acetate copolymer, a curing agent (polyisocyanate, etc.) and a plasticizer, and the ratio of each component is selected within a range that does not impair the heat seal property and the barrier property. it can. The amount of the curing agent (such as polyisocyanate) used is 1 to 12 parts by weight, preferably 2.5 to 10 parts by weight (for example, 3 to 9 parts by weight) with respect to 100 parts by weight of the vinyl chloride-vinyl acetate copolymer. Part), more preferably about 3.5 to 8 parts by weight (for example, 4 to 7 parts by weight). Moreover, the usage-amount of a plasticizer is 2-25 weight part (for example, 2.5-23 weight part) with respect to 100 weight part of vinyl chloride-vinyl acetate type copolymers, Preferably it is 3-20 weight part ( For example, it may be about 4 to 18 parts by weight), more preferably about 5 to 15 parts by weight (for example, 7 to 12 parts by weight).

  The thickness of the heat seal layer can be selected from a range of, for example, about 0.1 to 10 μm (for example, 0.2 to 7 μm), preferably about 0.25 to 5 μm (for example, 0.3 to 3 μm). Even if it is about ˜1 μm (for example, 0.2 to 0.7 μm), excellent heat sealability is exhibited without deteriorating the gas barrier property.

  The cellophane film and / or the heat seal layer may contain various additives such as stabilizers (antioxidants, ultraviolet absorbers, heat stabilizers, etc.); antistatic agents; crystal nucleus growth agents; Plasticizers such as acid esters; fillers; waxes (higher fatty acid amides, higher fatty acids and salts thereof, higher fatty acid esters, natural waxes such as minerals and plants, synthetic waxes such as polyethylene); particulate lubricants (silica) Inorganic lubricants such as system fine particles and alumina based microparticles, organic lubricants such as polyethylene microparticles and acrylic microparticles), and the like. The amount of these additives used can be appropriately selected according to the type of additive, the type of layer to be added, and the like. For example, in the heat seal layer, the stabilizer is often used in a range of about 10 to 1000 ppm relative to the resin component constituting the layer, and the wax is 0 per 100 parts by weight of the resin component constituting the layer. 0.1 to 5 parts by weight (for example, 0.5 to 3 parts by weight), and the particulate lubricant is 0.05 to 2 parts by weight (for example, 100 parts by weight of the resin component constituting the layer). , 0.1 to 1 part by weight, preferably 0.2 to 0.5 part by weight).

The film of the present invention can greatly improve the water vapor barrier property by covering the cellophane surface with a heat seal layer. For example, when the heat seal layer is formed on one surface of a single-layer cellophane film, the water vapor barrier property (unit: g / m ² · MPa · day) is 300 or less (eg, about 10 to 250), preferably It is 200 or less (for example, about 20 to 180), more preferably 170 or less (for example, about 30 to 170), and usually about 40 to 170 (for example, 50 to 160).

  In addition, when the heat seal layer is formed on one surface of a single-layer cellophane film and the heat seal layers are adhered to each other at a temperature of 90 ° C., the heat seal strength (unit: mN / 15 mm) is 800 or more. Breaking strength (for example, 900 to 2500), preferably 1000 or more to breaking strength (for example, 1100 to 2300), more preferably about 1100 or more to breaking strength (for example, 1200 to 2200), usually 1300 to 2200 ( For example, about 1500 to 2000).

  The heat-sealable film of the present invention includes a vinyl chloride-vinyl acetate copolymer, a curing agent (such as polyisocyanate), and a plasticizer (such as an aliphatic polyester component) on at least one surface of a cellophane film. It can be manufactured by forming a layer. The heat seal layer covering the cellophane surface may be formed by laminating the resin composition layer containing the component directly or via an adhesive, but is formed by applying a coating agent containing the component. There are many cases.

  The coating agent is in the form of a resin composition composed of the vinyl chloride-vinyl acetate copolymer, a curing agent (such as polyisocyanate), and a plasticizer (such as an aliphatic polyester component) (for example, a melt coating composition). In general, it is often in the form of either a solution or a dispersion containing a solvent. Examples of the solvent include hydrocarbons (aliphatic hydrocarbons such as hexane and octane, alicyclic hydrocarbons such as cyclohexane, aromatic hydrocarbons such as benzene, toluene, and xylene), and halogenated hydrocarbons. (Dichloromethane etc.), esters (ethyl acetate, butyl acetate etc.), ketones (acetone, methyl ethyl ketone, cyclohexanone etc.), ethers (dioxane, diethyl ether, tetrahydrofuran etc.), cellosolve acetates and the like. These solvents may be used as a mixed solvent. If necessary, a solvent having an active hydrogen atom, for example, alcohols (ethanol, propanol, isopropanol, cyclohexanol, etc.), cellosolves, carbitols and the like may be used in combination.

  The said coating agent may contain the said various additives, and in order to improve applicability | painting, it may contain conventional additives, such as an antifoamer and a viscosity modifier, for example.

  The coating agent may be applied to at least one surface (cellophane surface) of the cellophane film, or may be applied to both surfaces. The coating method is not particularly limited, and conventional methods such as an air knife coating method, a roll coating method, a gravure coating method, a blade coating method, a dip coating method, a spray method, and the like can be employed. After apply | coating the said coating agent, a heat seal layer can be formed by drying at the temperature of about 50-150 degreeC, for example, and making it age | cure | ripen or harden | cure as needed.

  The heat sealable film of the present invention has excellent heat sealability and water vapor gas barrier properties (moisture resistance) as described above. Moreover, the transparency is high and the contents can be easily seen. Therefore, the heat-sealable film can be suitably used as various packaging materials such as foods, pharmaceuticals, and electronic parts (such as precision electronic parts).

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

Example 1
Vinyl chloride-vinyl acetate-maleic acid copolymer (manufactured by Dow Chemical Co., UCAR Solution Vinyl Resins VMCH, number average molecular weight: 27000) and a mixed solvent of toluene and methyl ethyl ketone (weight ratio: toluene / methyl ethyl ketone = 1/1) ) At a solid content concentration of 10% by weight, and 5 parts by weight of trifunctional polyisocyanate (manufactured by Nippon Polyurethane Co., Ltd., Coronate L) with respect to 100 parts by weight of the vinyl chloride-vinyl acetate-maleic acid copolymer. 10 parts by weight of poly (1,3-butylene adipate) having a number average molecular weight of 1300 to 1700 (manufactured by Daihachi Chemical Industry Co., Ltd., BAA-15), 2 parts by weight of paraffin wax having a melting point of 125 ° C., and silica fine particles 0.3 After adding a weight part, it stirred at 70 degreeC for 1 hour, and prepared the coating liquid. The above coating solution was applied to one side of a # 300 cellophane film (thickness 20 μm, basis weight 30 g / m ² ) at an applied amount of 0.9 g / m ² after drying, and dried to form a heat seal layer. A characteristic film was obtained.

Examples 2-9 and Comparative Examples 1-3
The vinyl chloride-vinyl acetate-maleic acid copolymer resin described in Example 1 and the polyisocyanate and polyester plasticizer were used in the proportions (parts by weight) described in Table 1, and vinyl chloride-vinyl acetate-malein. A coating solution was prepared in the same manner as in Example 1 using 2 parts by weight of paraffin wax having a melting point of 125 ° C. and 0.3 parts by weight of silica fine particles per 100 parts by weight of the acid copolymer. These coating liquids were applied to one side of a # 300 cellophane film (thickness 20 μm, basis weight 30 g / m ² ) at a coating amount 0.9 g / m ² after drying, and dried to form a heat seal layer. A heat-sealable film was obtained.

  In addition, the symbol of Table 1 shows the following components.

(A1): Vinyl chloride-vinyl acetate-maleic acid copolymer; “UCAR Solution Vinyl Resins VMCH” manufactured by Dow Chemical Co., Ltd., several molecular weights 27,000, 86% by weight vinyl chloride, 13% by weight vinyl acetate, 1% maleic acid %
(A2): Vinyl chloride-vinyl acetate-maleic acid copolymer; “SOLBIN M” manufactured by Nissin Chemical Industry Co., Ltd., several molecular weights 32,000, 86% by weight vinyl chloride, 13% by weight vinyl acetate, 1% maleic acid %
(B1): Polyisocyanate; manufactured by Nippon Polyurethane Industry Co., Ltd., “Coronate L”, solid content 75% by weight, isoanate content 12%
(B2): Polyisocyanate; manufactured by Mitsui Chemicals Polyurethane Co., Ltd., “Takenate A-3”, solid content 75% by weight, isocyanate content 12.2 to 13.2% (trimethylolpropane adduct)
(B3): Polyisocyanate; manufactured by Nippon Polyurethane Industry Co., Ltd., “Coronate HL”, solid content 75% by weight, isoanate content 12%
(C1): polyester plasticizer “poly (1,3-butylene adipate)”; manufactured by Daihachi Chemical Industry Co., Ltd., “BAA-15”, number average molecular weight 1300 to 1700
(C2): Aliphatic dicarboxylic acid ester plasticizer “Diisononyl adipate”; “DINA” manufactured by Daihachi Chemical Industry Co., Ltd.
(C3): Aliphatic dicarboxylic acid ester plasticizer “dibutyl sebacate”; “DBS” manufactured by Daihachi Chemical Industry Co., Ltd.
The heat seal strength and water vapor permeability of the films obtained in Examples and Comparative Examples were measured as follows.

[Heat seal strength]
The films of Examples and Comparative Examples were allowed to stand at 20 ° C. under a relative humidity of 65% for 2 hours, then cut into small pieces, and the heat seal layer surfaces of the two small pieces were brought into close contact with each other, 1 kg / cm ² , 90 ° C. and After heat-sealing at 120 ° C., a test piece was prepared by cutting to a width of 15 mm. After leaving this test piece at 20 ° C. and 65% relative humidity for 2 hours, each end of the two films of the test piece was pulled in the opposite direction using a tensile tester at a crosshead speed of 300 mm / min. The maximum strength was defined as the heat seal strength. Moreover, the measurement was performed with 3 specimens, and the measured value was the average value. The unit is mN / 15 mm.

[Water vapor transmission rate]
In order to evaluate the water vapor barrier property, the water vapor transmission rate was measured by the measuring method (cup method) of JIS Z0208. The unit is g / m ² · MPa · 24 hr (day).

  The results are shown in Table 1.

  As is clear from Table 1, the heat seal strength and the water vapor barrier property were higher in the examples than in the comparative examples.

Claims (11)

  A heat sealable film in which a heat seal layer containing a vinyl chloride-vinyl acetate copolymer, a curing agent, and a plasticizer is formed on at least one surface of a cellophane film.   The heat-sealable film according to claim 1, wherein the number average molecular weight of the plasticizer is 200 to 3500. The heat according to claim 1 or 2, wherein the plasticizer is at least one selected from a citrate ester plasticizer, a C _6-10 aliphatic dicarboxylic acid diC _4-12 alkyl ester plasticizer, and a polyester plasticizer. Sealing film. The plasticizer is at least one selected from an adipic acid plasticizer, an azelaic acid plasticizer, a sebacic acid plasticizer, and a polymer of C _2-6 alkanediol and adipic acid. The heat-sealable film according to any one of the above.   The heat-sealable film according to any one of claims 1 to 4, wherein the curing agent is a polyisocyanate.   The vinyl chloride-vinyl acetate copolymer is a copolymer of vinyl chloride, vinyl acetate, and a monomer having a carboxyl group or an acid anhydride group, and the vinyl chloride content is 80% by weight or more. The heat-sealable film according to any one of claims 1 to 5.   The heat-sealable film according to any one of claims 1 to 6, wherein the vinyl chloride-vinyl acetate copolymer is a vinyl chloride-vinyl acetate-maleic acid copolymer.   The heat sealable film according to any one of claims 1 to 7, wherein the heat seal layer is formed of a coating agent containing a vinyl chloride-vinyl acetate copolymer having a free vinyl acetate content of 0.1 wt% or less. .   The heat seal layer is formed of a coating agent containing 1 to 12 parts by weight of a curing agent and 2 to 25 parts by weight of a plasticizer with respect to 100 parts by weight of a vinyl chloride-vinyl acetate copolymer. The heat-sealable film in any one of -8. The water vapor barrier property is 300 g / m ² · MPa · day or less, and the heat seal strength is 800 mN / 15 mm or more when the heat seal layers are adhered to each other at a temperature of 90 ° C. 10. The heat-sealable film described in 1.   A method for producing a heat-sealable film, wherein a heat-seal layer comprising a vinyl chloride-vinyl acetate copolymer, a curing agent and a plasticizer is formed on at least one surface of a cellophane film.