JP5247199B2 - Laminated film - Google Patents

Description

  The present invention relates to a laminated film of a polypropylene film and a sealant resin, and relates to a laminated film having excellent interlayer adhesion between both substrates and having useful properties as a packaging material, and a method for producing the same.

  Plastic films represented by polyolefin films, polyamide films, polyester films and the like are indispensable in the field of packaging materials and the like. Above all, polyolefin film has a good balance between various physical properties and economy and is a highly demanding film material. Among them, polypropylene film has characteristics such as rigidity, low slip, wear resistance and chemical resistance. It is generally recognized as an important packaging material. When these plastic films are used as packaging materials, in many cases, heat-sealability is obtained by laminating a heat-sealable resin such as polyethylene, polypropylene, or ethylene-vinyl acetate copolymer on one or both sides of the film. Various packaging forms are taken by giving. However, a polypropylene film has a significantly poor adhesion to a sealant resin compared to other plastic films such as a polyamide film and a polyester film, so that it is difficult to realize lamination with excellent interlayer adhesion, which has been a problem in the past. It was.

  Attempts have been made for a long time to improve the interlaminar adhesion with a sealant resin to a polypropylene substrate. Patent Document 1 discloses a method of extruding and laminating a blend resin of polyethylene and propylene copolymer to a biaxially stretched polypropylene film, and Patent Document 2 has a specific physical property to a polypropylene film having specific physical properties. A laminated film obtained by extruding and laminating an ethylene copolymer is shown. However, the propylene copolymer and the ethylene copolymer used in such a method are more expensive than general-purpose sealant resins such as polyethylene resins and polypropylene resins, and further provide sufficient heat sealability. However, since it is necessary to laminate such an expensive sealant resin thickly, it is economically disadvantageous.

For such a method, a method is known in which an adhesive layer is provided on a polypropylene film and a general-purpose sealant resin is laminated via the adhesive layer (here, the adhesive layer is generally an anchor layer, an anchor coat layer, a primer). Although it may be expressed as a layer or the like, it is expressed as an adhesive layer in the present invention). In this case, the cost of providing the adhesive layer is generated, but it is possible to obtain economic merit by reducing the thickness of the adhesive layer. As such a method, Patent Document 3 discloses a laminated film for extrusion lamination in which a biaxially stretched film is provided with an adhesive layer composed of a polyolefin resin, a polyurethane resin and a melamine-based crosslinking agent, and Patent Document 4 discloses a biaxially stretched polypropylene. A laminated film in which an adhesive layer made of polyethyleneimine or polyepoxy compound is provided on the film is shown. However, in Patent Document 3, there is no description about the adhesiveness of the polypropylene film, and in the laminated film of Patent Document 4, interlayer adhesion is insufficient and further improvement is required.
JP 2005-138345 A JP 2004-209672 A JP 2004-148729 A JP-A-55-37338

  The present invention is intended to provide a laminated film having good interlayer adhesion between a polypropylene film and a sealant resin, and a method for producing them, in order to solve the above-described problems.

  As a result of intensive studies to solve the above problems, the present inventors found that in a laminated film of a polypropylene film and a sealant resin, an adhesive layer having a specific composition was provided between the polypropylene film and the sealant resin layer. The present inventors have found that a laminated film having good interlayer adhesive strength can be obtained, and have reached the present invention.

That is, the gist of the present invention is as follows.
(1) In a laminated film in which a sealant layer is laminated on at least one surface of a polypropylene film via an adhesive layer, the adhesive layer contains a (meth) acrylic acid ester component and an unsaturated carboxylic acid component amount is 0.01. A mixture of an acid-modified polyolefin resin (A) of ˜5.0 mass% and a polyether-type polyurethane resin (B) having a glass transition temperature of 5 ° C. or less, and the mass ratio (A) / (B) is 99. / 1-20 / 80 laminated film.
( 2 ) The laminated film according to (1), wherein the sealant resin is a polyethylene resin and / or a polypropylene resin.
( 3 ) An aqueous dispersion containing a resin solid content of the polyolefin resin (A) and the polyether-type polyurethane resin (B) in a mass ratio (A) / (B) = 99/1 to 20/80, and polypropylene. The method for producing a laminated film according to (1) or (2), wherein the film is applied to at least one side of the film and then dried to form an adhesive layer, and then a sealant resin is laminated via the adhesive layer.
( 4 ) The method for producing a laminated film according to ( 3 ), wherein the sealant resin is laminated by extrusion lamination.

  According to the laminated film of the present invention, a laminated film having high adhesion between the layers of the polypropylene film and the sealant resin can be obtained, and it is suitable as a packaging material for food, medicine, cosmetics, detergents, pharmaceuticals, toys, medical materials, electronic materials, etc. Can be used for

  Since the production method of the present invention can easily form the adhesive layer of the laminated film of the present invention, it has excellent productivity. In addition, when an aqueous dispersion is used, the wettability when applied to a polypropylene film is improved and the productivity is improved, and the use of an aqueous medium gives consideration to the environment.

  Furthermore, an extrusion laminating process that is advantageous in terms of cost can be employed as a method for laminating the sealant resin.

  Hereinafter, the present invention will be described in detail.

(Polypropylene film)
The composition of the polypropylene film used in the present invention is not particularly limited, but a polypropylene homopolymer based on a propylene homopolymer, an α-olefin mainly composed of propylene, or a propylene-α-olefin copolymer obtained by block copolymerization. A polypropylene copolymer film or sheet made of a polymer or the like can be used. In the above, as the α-olefin, ethylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene, 5-ethylidene-2-norbonene, 5-methyl-2-norbonene An olefin monomer such as 1,4-hexadiene can be used.

  The polypropylene film may be either a non-stretched film or a stretched film, but a uniaxial or biaxially stretched film is preferable and a biaxially stretched film is more preferable from the viewpoint of imparting transparency and gloss. The thickness of the film is not particularly limited, and usually 5 to 500 μm is used.

  The polypropylene film is preferably subjected to surface activation treatment on the surface on which the adhesive layer is provided in order to improve adhesiveness. Examples of the surface activation treatment include corona discharge treatment, flame plasma treatment, atmospheric pressure plasma treatment, low pressure plasma treatment, ozone treatment, electron beam irradiation treatment, ultraviolet irradiation treatment, chemical treatment, and solvent treatment. Corona discharge treatment is preferred from the balance of the adhesion effect.

  Further, the polypropylene film may be subjected to a vapor deposition treatment of a metal, an inorganic oxide or the like in order to impart barrier properties.

<Polyolefin resin (A)>
The polyolefin resin (A) is an acid-modified polyolefin resin containing a (meth) acrylic acid ester component and having an unsaturated carboxylic acid component amount of 0.01 to 5.0% by mass.

  Examples of the olefin component include olefins having 2 to 6 carbon atoms such as ethylene, propylene, isobutylene, 1-butene, 1-pentene and 1-hexene, and a mixture thereof may be used. Among these, olefins having 2 to 4 carbon atoms such as ethylene, propylene, isobutylene and 1-butene are more preferable, and ethylene is particularly preferable.

  The unsaturated carboxylic acid component may be an acid anhydride, such as acrylic acid, methacrylic acid, ethacrylic acid, maleic acid, fumaric acid, itaconic acid, maleic anhydride, itaconic anhydride, monomethyl maleate, monoethyl maleate, etc. And a mixture thereof may be used. Among these, maleic anhydride, acrylic acid, and methacrylic acid are preferable. The form of copolymerization of the unsaturated carboxylic acid component is not limited, and examples thereof include random copolymerization, block copolymerization, and graft copolymerization.

  Content of an unsaturated carboxylic acid component is 0.01-5.0 mass% of the whole polyolefin resin (A), 0.1-4.5 mass% is preferable, 0.5-4.0 mass% Is more preferable, 1.0-3.5 mass% is further more preferable, and 2.0-3.0 mass% is especially preferable. When the content of the unsaturated carboxylic acid or its anhydride (A1) is less than 0.01% by mass, the adhesiveness with the polypropylene substrate tends to be lowered, and further when used as an aqueous dispersion described later. Aqueous dispersion becomes difficult. When the content is more than 5.0% by mass, the adhesion to the polypropylene base material tends to be lowered, and further, when used as an aqueous dispersion described later, the resin aggregates when mixed with the thermoplastic resin (B). Minutes tend to settle.

  The polyolefin resin (A) needs to contain a (meth) acrylic acid ester component in order to improve the adhesion to the polypropylene substrate. The (meth) acrylic acid ester component is preferably in the range of (olefin component) / {(meth) acrylic acid ester component} = 55/45 to 99/1 in relation to the mass ratio with the olefin component. The range of 60/40 to 98/2 is more preferable, and the range of 75/25 to 95/5 is most preferable. When the mass ratio of the (meth) acrylic acid ester component is less than 1% by mass, the adhesion with the polypropylene substrate tends to be lowered, and further, it is difficult to disperse in water when used as an aqueous dispersion described later. Tend to be. On the other hand, when it is more than 45% by mass, the rigidity of the adhesive layer tends to be low and sufficient interlayer adhesion strength tends not to be obtained.

  Examples of the (meth) acrylic acid ester component include lower alkyl esters of (meth) acrylic acid such as methyl acrylate, ethyl acrylate, methyl methacrylate, and ethyl methacrylate, and methyl acrylate and ethyl acrylate are preferable.

  As the polyolefin resin (A), ethylene- (meth) acrylate methyl-maleic anhydride terpolymer or ethylene-ethyl (meth) acrylate-maleic anhydride terpolymer is most preferable.

  In the polyolefin resin (A), other monomers may be copolymerized at 20% by mass or less of the entire resin. Examples thereof include alkyl vinyl ethers having 3 to 30 carbon atoms such as methyl vinyl ether and ethyl vinyl ether, dienes, (meth) acrylonitrile, halogenated vinyls, halogenated vinylidenes, carbon monoxide, and sulfur dioxide.

The polyolefin resin (A) preferably has a melt flow rate in the range of 0.01 to 500 g / 10 min at 190 ° C. and a load of 2160 g, which is a measure of molecular weight. More preferably 1 to 250 g / 10 minutes, more preferably 2 to 150 g / 10 minutes, particularly preferably 2 to 100 g / 10 minutes, and most preferably 2 to 80 g / 10 minutes. When the melt flow rate is less than 0.01 g / 10 minutes, it becomes difficult to process and disperse the resin in water. On the other hand, when it exceeds 500 g / 10 minutes, the rigidity of the adhesive layer decreases and sufficient interlayer adhesion strength is obtained. Although there is no particular limitation on the synthesis method of the polyolefin resin (A) that tends to disappear, it is generally obtained by high-pressure radical copolymerization of the monomer constituting the polyolefin resin in the presence of a radical generator. Moreover, the unsaturated carboxylic acid component may be graft-copolymerized (graft-modified).

<Thermoplastic resin (B)>
In the laminate of the present invention, the adhesive layer comprises a polypropylene film and a sealant by mixing a polyolefin resin (A) and a thermoplastic resin (B) having a glass transition temperature (hereinafter referred to as Tg) of 5 ° C. or less. Interlayer adhesion with resin is improved. The reason why the interlayer adhesion is improved by mixing the thermoplastic resin (B) having a Tg of 5 ° C. or less with the polyolefin resin (A) is not clear, but the polyolefin resin (A) has a Tg of about −50 to 0 ° C. The thermoplastic resin having a Tg close to or lower than the Tg of the polyolefin resin (A) is mixed with such a resin to further soften the polyolefin resin (A). It is presumed to have an effect of improving the followability to fine irregularities on the surface of the film.

  The Tg of the thermoplastic resin (B) needs to be 5 ° C. or less, preferably 0 ° C. or less, more preferably −5 ° C. or less, further preferably −10 ° C. or less, from the viewpoint of the effect of improving adhesiveness, −20 A temperature of not higher than ° C is particularly preferred. Although a minimum is not specifically limited, The minimum of Tg of the generally available thermoplastic resin is about -70 degreeC. When Tg exceeds 5 ° C., the effect of improving the adhesion between the polypropylene film and the sealant layer is poor.

  Tg of the thermoplastic resin (B) can be measured with a dynamic viscoelasticity measuring device (DMA). The temperature at the maximum point of the peak of the loss elastic modulus (E ″) found in the temperature range of the refraction point of the measured storage elastic modulus (E ′) was defined as Tg.

  When the aqueous dispersion is used when forming the adhesive layer of the present invention, the aqueous dispersion of the polyolefin resin (A) alone shows repellency of the aqueous dispersion during coating on the polypropylene film. On the other hand, the effect of improving repellency (paintability) can be seen by mixing the thermoplastic resin (B) having a Tg of 5 ° C. or less. Thus, the blending of the thermoplastic resin (B) has an advantageous effect in a specific production method.

  Examples of the thermoplastic resin having a Tg of 5 ° C. or lower include polyester resins, polyurethane resins, polyolefin resins, polyacrylic resins, polyvinyl chloride resins, polyamide resins, etc. Among them, the effect of improving adhesiveness is high. Therefore, a polyester resin and a polyurethane resin are preferable.

<Polyester resin>
The polyester resin used as the thermoplastic resin (B) is not particularly limited as a constituent component, and examples thereof include polyesters obtained by a known production method comprising an acid component and an alcohol component.

  The acid component of the polyester resin includes terephthalic acid, isophthalic acid, orthophthalic acid, naphthalenedicarboxylic acid, biphenyldicarboxylic acid, oxalic acid, succinic acid, succinic anhydride, adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, hydrogenated Dimer acid, fumaric acid, maleic acid, maleic anhydride, itaconic acid, itaconic anhydride, citraconic acid, citraconic anhydride, dimer acid, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2- Examples include cyclohexanedicarboxylic acid, 2,5-norbornenedicarboxylic acid and its anhydride, tetrahydrophthalic acid and its anhydride, and the like.

  Examples of the alcohol component of the polyester resin include ethylene glycol, 1,2-propylene glycol, 1,3-propanediol, 1,4-butanediol, 2-methyl-1,3-propanediol, 1,5-pentanediol, Neopentyl glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,9-nonanediol, 2-ethyl-2-butylpropanediol, 1,4-cyclohexanedimethanol, diethylene glycol, triethylene glycol Ethylene oxide is added to two phenolic hydroxyl groups of bisphenols such as ethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and 2,2-bis (4-hydroxyethoxyphenyl) propane. Or glycols such as obtained by propylene oxide was to several mols, respectively, and the like.

<Polyurethane resin>
The polyurethane resin used as the thermoplastic resin (B) is a polymer containing a urethane bond in the main chain, and is obtained, for example, by a reaction between a polyol compound and a polyisocyanate compound. Examples of the polyurethane resin include a polyether type polyurethane resin, a polyester type polyurethane resin, a polycarbonate type polyurethane resin, a polyester polycarbonate type polyurethane resin, and the like. Among these, a polyether type polyurethane resin having a high effect of improving adhesiveness is preferable.

  As the polyol component constituting the polyurethane, 1,3-butanediol, 1,4-butanediol, 1,2-propanediol, 1,3-propanediol, 1,6-hexanediol, neopentyl glycol, 1, In addition to alkylene diols and alicyclic diols such as 4-cyclohexanedimethanol, methyl-1,5-pentanediol, 1,8-octanediol, 2-ethyl-1,3-hexanediol, polyether polyols, polyesters Examples include polyols, polyester polycarbonate polyols, and polycarbonate polyols. Among these, polyether polyols having a high effect of improving adhesiveness are preferable. Examples of polyether polyols include polyoxyethylene polyols such as polyethylene glycol, polyoxypropylene polyols such as polypropylene glycol, and polyoxyethylene / propylene polyols such as polytetramethylene ether glycol, among which polyethylene glycol and polytetramethylene. Polyether methylene glycol such as glycol is preferable because it is easily available, and polytetramethylene glycol is more preferable because adhesion is improved. Although the molecular weight of polyether diol is not specifically limited, The thing of the range of 1000-10000 is preferable and 1000-5000 are especially preferable. Polyols may be used as a mixture.

  As the polyisocyanate component constituting the polyurethane resin, one or a mixture of two or more known aromatic, aliphatic and alicyclic diisocyanates can be used. Specific examples of diisocyanates include tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 1,3-phenylene diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, 1,5-naphthalene diisocyanate, isophorone diisocyanate, dimethyl diisocyanate, lysine diisocyanate. , Hydrogenated 4,4′-diphenylmethane diisocyanate, hydrogenated tolylene diisocyanate, dimerized isocyanate obtained by converting the carboxyl group of dimer acid to an isocyanate group, and adducts, biurets, isocyanurates, etc. Isophorone diisocyanate is preferred because of improved properties.

  Furthermore, the thermoplastic polyurethane resin used in the present invention preferably has an anionic group for use as an aqueous dispersion described later. Examples of the anionic group include a carboxyl group, a sulfonic acid group, a sulfuric acid group, and a phosphoric acid group, and a carboxyl group and a sulfonic acid group are preferable. These anionic groups may be partially salted.

<Adhesive layer>
In the present invention, the adhesive layer is a mixture of the polyolefin resin (A) and the thermoplastic resin (B), and the mass ratio thereof is (A) / (B) = from the viewpoint of the effect of improving the adhesion between the polypropylene film and the sealant layer. 99 / 1-20 / 80, preferably (A) / (B) = 97 / 3-50 / 50, more preferably (A) / (B) = 95 / 5-60 / 40, (A) / (B) = 90/10 to 70/30 is more preferable, and (A) / (B) = 80/20 to 70/30 is particularly preferable. If the polyolefin resin (A) exceeds 99% by mass, the wettability with respect to the polypropylene film tends to deteriorate rapidly, and if the polyolefin resin (A) is less than 20% by mass, sufficient interlayer adhesive strength cannot be obtained.

  To the mixture of the polyolefin resin (A) and the thermoplastic resin (B), in order to further improve the adhesion, 0 to 20 parts by mass of a tackifier may be added to 100 parts by mass of the mixture. Is preferably 1 to 20 parts by mass, more preferably 3 to 20 parts by mass, and even more preferably 5 to 20 parts by mass. When it exceeds 20 mass parts, the adhesive improvement effect tends to be lowered. As the tackifier, various known ones can be used, and examples thereof include terpene resins, rosins, rosin derivatives, and the like. One of these can be used alone or a mixture of two or more can be used. Examples of terpene resins include α-pinene resins, β-pinene resins, aromatic terpene resins obtained by copolymerizing terpenes such as α-pinene and β-pinene, and aromatic monomers such as styrene, and hydrogens thereof. Examples include chemicals. Examples of rosins include raw rosin of gum rosin, wood rosin or tall oil rosin, or stabilized rosin or polymerized rosin obtained by disproportionating or hydrogenating the raw rosin. Examples of the rosin derivative include rosin esters and rosin phenols. As the rosin ester, the rosin ester obtained by esterifying the rosin and the polyhydric alcohol, the raw rosin is partially fumarated or maleated, and then partially maleated or partially fumarated obtained by esterification. Polyhydric alcohol ester of rosin, partial maleated or partially fumarated disproportionated rosin polyhydric alcohol ester obtained by partially fumarating or maleating raw material rosin and then disproportionating and then esterifying Say. The rosin phenols are those obtained by adding phenols to rosins and thermally polymerizing them, or subsequently esterifying them. The polyhydric alcohol used for the esterification is not particularly limited, and diethylene glycol, glycerin, trimethylolpropane, trimethylolethane, 1,2,6-hexanetriol, 1,2,4-butanetriol, penta Various well-known things, such as erythritol, can be illustrated. Among these tackifiers, terpene resins or rosin esters are preferable. Moreover, the aqueous dispersion of the said various tackifiers can also be utilized.

  In addition to the mixture of the polyolefin resin (A) and the thermoplastic resin (B), the adhesive layer may contain an anti-blocking agent, a pigment, a dye, a leveling agent, a compatibilizer, an antifoaming agent and an anti-waxing agent depending on the purpose. Further, a pigment dispersant, an ultraviolet absorber and the like may be added within a range not impairing the effects of the present invention.

  The adhesive layer in the present invention is formed on at least one side of a polypropylene film. Examples of the forming method include a method of extruding and laminating a mixture of a polyolefin resin (A) and a thermoplastic resin (B) to a polypropylene film with a T-die, and a polypropylene and adhesive layer composition resin (polyolefin resin (A) and thermoplastic resin). Examples thereof include a method of co-extrusion of a resin (B) mixture, and a method of coating a polypropylene film with a solution or an aqueous dispersion of a polyolefin resin (A) and a thermoplastic resin (B).

  When the extrusion laminating method is adopted, the adhesive layer alone may be laminated, or it can be coextruded with a sealant resin described later. However, at the time of co-extrusion, it is necessary to extrude so that an adhesive layer is formed on the polypropylene film side. When adopting a method of co-extrusion of polypropylene and adhesive layer composition resin, it is generally laminated by three or more types of co-extrusion including a sealant resin. Even in this case, the polypropylene layer, the adhesive layer, and the sealant resin layer need to be laminated in this order. Among these methods, it is more preferable to form an adhesive layer by a solution or an aqueous dispersion coat capable of making the adhesive layer thinner, and it is particularly preferable to use an aqueous dispersion from the viewpoint of the working environment.

  The thickness of the adhesive layer is preferably 0.005 to 20 μm, more preferably 0.01 to 5 μm, still more preferably 0.05 to 2 μm, and particularly preferably 0.1 to 1 μm. When the thickness is less than 0.005 μm, sufficient adhesion cannot be obtained, and when the thickness is more than 20 μm, the amount of resin used increases and the cost increases.

<Aqueous dispersion>
In the present invention, a production method using an aqueous dispersion, which is a preferred method for forming an adhesive layer, will be described. The aqueous dispersion is one that is uniformly dispersed in an aqueous medium containing water as a main component.

  As an aqueous dispersion for forming an adhesive layer, a polyolefin resin (A) and a thermoplastic resin (B) are used in a mass ratio of resin solids of (A) / (B) = 99/1 to 20/80. An aqueous dispersion containing a range is used. The resin solid content can be determined by drying an appropriate amount of the aqueous dispersion weighed with a hot air dryer or the like, and measuring the mass when the mass of the residue (resin component) reaches a constant weight.

  The preparation method of the aqueous dispersion is not particularly limited as long as each raw material resin is uniformly mixed and dispersed in an aqueous medium, and any known method can be applied. For example, a polyolefin resin ( A method of mixing the aqueous dispersion of A) with the aqueous dispersion of the thermoplastic resin (B), and mixing the raw material resins of (A) and (B) by dry blending, melt kneading, etc. Examples thereof include an aqueous dispersion method. Among the above methods, a method of mixing two types of aqueous dispersions is preferable because it is simpler. If the raw material resin (B) is difficult to disperse in water by itself, the mixed resin can be obtained after the polyolefin resin (A) is melt-kneaded and mixed with a twin-screw extruder or the like. Aqueous dispersion may be possible.

  Examples of the aqueous dispersion method include a method in which the raw material resin is heated and stirred in an airtight container together with an aqueous medium mainly containing water and a basic compound. The aqueous medium is a medium composed of water and / or a water-soluble compound, and examples of the compound include a basic compound and a water-soluble organic solvent.

<Solution>
The adhesive layer of the laminate of the present invention may be formed by applying an organic solvent solution containing a polyolefin resin (A) and a thermoplastic resin (B) at a predetermined solid content ratio to a polypropylene film. it can. As the solvent, a common good solvent for the polyolefin resin (A) and the thermoplastic resin (B) can be appropriately used. Examples of such solvents include toluene, heptane, xylene, amylbenzene, isopropylbenzene, octane, cyclohexane, cyclohexylbenzene, cyclohexene, cyclopentane, dipentene, cymene, turpentine, hexane, pentane, mesitylene, Examples include hydrocarbons typified by methylcyclohexane and the like.

  As a method of coating the polypropylene film with the aqueous dispersion or solution described above, a known method can be appropriately employed. For example, using a gravure roll coating, reverse roll coating, wire bar coating, lip coating, air knife coating, curtain flow coating, spray coating, dip coating, or brush coating method, the polypropylene film is uniformly coated. If necessary, the film is set near room temperature and then subjected to heat treatment for drying or drying and baking, whereby a uniform resin film can be formed in close contact with the film surface. As a heating device at this time, a normal hot air circulation type oven, an infrared heater, or the like may be used.

<Sealant resin>
As the sealant resin constituting the laminate of the present invention, a conventionally known resin can be used as a polyolefin resin. For example, low density polyethylene, linear low density polyethylene, medium density polyethylene, high density polyethylene, etc. Polyethylene resins and polypropylene resins made of propylene homopolymers are preferred, and among them, polyethylene resins excellent in low-temperature heat sealing are particularly preferred. In the present invention, it is not particularly necessary to use a relatively expensive modified polyolefin resin having undergone modification such as copolymerization as the sealant layer, but it is necessary to have stronger adhesiveness or for the purpose of using the laminated film. If there are, they may be used. Examples of such sealant resins include ethylene resins such as ethylene-α-olefin, propylene resins such as propylene-α-olefin, and ethylene-α, β-unsaturated ethylene- (meth) acrylic acid copolymers. Esterified products of ethylene-α and β-unsaturated carboxylic acid copolymers such as carboxylic acid copolymer, ethylene-methyl (meth) acrylate copolymer, and ethylene in which carboxylic acid sites are crosslinked with sodium ion, zinc ion, etc. -Anionic anhydrides represented by ionic cross-linked products of α, β-unsaturated carboxylic acid copolymers, ethylene-maleic anhydride graft copolymers and ethylene- (meth) acrylic acid ester-maleic anhydride terpolymers Modified polyolefin, epoxy compound modified polyolefin such as ethylene-glycidyl methacrylate copolymer, vinyl Examples include vinyl silanes such as rutrimethoxysilane, vinyltriethoxysilane and methacryloxypropyltrimethoxysilane, acrylic silane-modified polyolefins, olefin copolymers, ethylene-vinyl alcohol copolymers, ethylene-vinyl acetate copolymers, etc. Can be mentioned. The above resins may be used singly, two or more types may be blended and used in multiple layers. If necessary, various additives such as an antioxidant, a tackifier, a filler, and various fillers can be added to these resins.

  Examples of the method of laminating the sealant resin include an extrusion laminating process in which the sealant resin is extruded by a T-die on the adhesive layer surface of the polypropylene film, and a dry laminating process in which a film made of the sealant resin is adhered to the adhesive layer surface of the polypropylene film. Among these, it is preferable to employ extrusion laminating which is simple and advantageous in terms of cost. In the extrusion, surface treatment such as ozone treatment may be performed on the molten sealant resin. In addition, when the sealant resin is multilayered by extrusion lamination, single layer extrusion may be repeated a plurality of times, or a plurality of resins may be multilayered by coextrusion.

  The thickness of the sealant resin layer is not particularly limited, but considering the suitability as a packaging material and the processability when laminated with other layers, the range of 3 to 300 μm is preferable for practical use, and 5 to 30 μm depending on the application. Is more preferable.

<Laminated film>
The laminated film of the present invention is a laminated film having good interlayer adhesion between the polypropylene film and the sealant resin, and the required interlayer adhesion strength cannot be generally specified depending on the purpose of use or use, but was cut to a width of 15 mm. 2. The peel strength when peeling between the propylene film and the sealant resin layer of the laminated film at a rate of 200 mm / min is preferably 1.5 N / 15 mm or more, more preferably 2.0 N / 15 mm or more. 0 N / 15 mm or more is more preferable, and 4.0 N / 15 mm or more is particularly preferable.

  In the laminated film of the present invention, when the polypropylene film surface is the outside and the sealant resin surface is the inside, another layer may be laminated on the further outside of the polypropylene film surface or further inside the sealant resin surface. Examples of the layer include thermoplastic resin, paper, synthetic paper, nonwoven fabric, and metal foil. However, generally, since the sealant resin surfaces are required to have a heat seal performance with the sealant resin surfaces or with another base material, it is usually unnecessary to further laminate another layer.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto. Various characteristics were measured or evaluated by the following methods.

<Resin characteristics>
(1) Configuration of polyolefin resin (A)
^It calculated | required from < ¹ > H-NMR analysis (The product made by Varian, 300MHz). The polyolefin resin was measured at 120 ° C. using orthodichlorobenzene (d ₄ ) as a solvent.
(2) Melt flow rate of polyolefin resin (A) It measured by the method of JIS6730 description (190 degreeC, 2160g load).
(3) Glass transition temperature (Tg) of thermoplastic resin (B)
Storage elastic modulus (E ') measured using a dynamic viscoelasticity measuring device (Orientec, RHEOVIBRON DDV-III-EP) under conditions of a heating rate of 3 ° C / min and a measuring temperature of -50 ° C to 150 ° C. The glass transition temperature (Tg) was defined as the temperature at the peak of the loss elastic modulus (E ″) found in the temperature range of the refraction point. When the thermoplastic resin (B) is a solid, use a hot press machine. A press film having a thickness of 150 μm was prepared and cut into a rectangular piece of 8 mm × 35 mm, and when the thermoplastic resin (B) was an aqueous dispersion, the aqueous dispersion was dried on a Teflon (registered trademark) sheet, The dried coating film obtained by completely drying the aqueous medium was peeled off from the Teflon (registered trademark) sheet, a dried coating film having a thickness of 150 μm was selected, and cut into a rectangle of 8 mm × 35 mm as a test method. 5 and the measured value is the average value .

<Adhesive layer properties>
(1) Paintability When an adhesive layer is formed on a polypropylene film using an aqueous dispersion, the degree of application of the coat layer (adhesive layer) of the polypropylene film in the coating step and drying step of the aqueous dispersion is visually checked according to the following criteria. evaluated.

○: No repelling △: Partial repelling can be confirmed ×: Repelling is observed on the entire surface, and an adhesive layer cannot be formed

<Laminated film characteristics>
(1) Interlayer adhesion of polypropylene film / sealant resin A test piece having a width of 15 mm was cut out from a polypropylene film on which a sealant resin was laminated, and a trigger was created between the layers of the sealant resin and the polypropylene film. Using a company Intesco precision universal material testing machine 2020), the peel strength was measured by T-type peeling at a tensile speed of 200 mm / min. The measurement was performed at n = 5 and the average value was adopted.

<Raw material polyolefin resin>
As the polyolefin resin, Bondine HX8290 (manufactured by Arkema, hereinafter referred to as HX8290) and Primacol 5980I (manufactured by Dow Chemical Co., hereinafter 5980I), which are commercially available products, were used. The properties of the polyolefin resin are summarized in Table 1. HX8290 and 5980I were used as aqueous dispersions by the following method.

<Production of HX8290 aqueous dispersion>
Using a pressure-resistant autoclave provided with a stirring blade, 25 parts by mass of HX8290, 20 parts by mass of 2-propanol, 0.9 part by mass of triethylamine and 51 parts by mass of distilled water were charged into the autoclave, and after sealing, Stirring was performed at a rotational speed of 100 rpm. Subsequently, the system temperature of the autoclave was heated to 120 ° C., and further stirred for 60 minutes while maintaining 120 ° C. Thereafter, the mixture was cooled to about 40 ° C. while stirring with air cooling at 100 rpm, and then filtered through a 300 mesh stainless steel filter to obtain an aqueous resin dispersion of HX8290. The solid content concentration of this aqueous dispersion was 25% by mass.

<Manufacture of 5980I>
Using a pressure-resistant autoclave provided with a stirring blade, 20 parts by weight of 5980I, 5.6 parts by weight of triethylamine and 75 parts by weight of distilled water were charged into the autoclave, and after sealing, the stirring blade was stirred at a rotational speed of 100 rpm. Subsequently, the system temperature of the autoclave was heated to 120 ° C., and further stirred for 60 minutes while maintaining 120 ° C. Thereafter, the mixture was cooled to about 40 ° C. while stirring with air cooling at a rotation speed of 100 rpm, and then filtered through a 300 mesh stainless steel filter to obtain a 5980I aqueous resin dispersion. The solid content concentration of this aqueous dispersion was 20% by mass.

<Various thermoplastic resins>
As the polyester resin, commercially available unitika elitel (manufactured by Unitika) KZT-0507 (solid content concentration 25% by mass, resin solid content Tg = −20 ° C., hereinafter referred to as KZT-0507), unitika elitel OX-5127 ( Tg = −9 ° C., hereinafter OX-5127), Unitika Eritel UE-3220 (Tg = 4 ° C., hereinafter UE-3220), Unitika Eritel UE-3500 (Tg = 17 ° C., hereinafter UE-3500) were used. .

  The form of KZT-0507 is an aqueous dispersion, the form of OX-5127, UE-3220 and UE-3500 is solid.

  Examples of polyurethane resins include polyether-type polyurethane aqueous dispersions U-1 (Tg = −32 ° C.), polyester-type polyurethane aqueous dispersions U-2 (Tg = −29 ° C.), and commercially available polyurethane aqueous solutions. Dispersion hydran AP (manufactured by Dainippon Ink & Chemicals, Inc., solid content concentration 23 mass%, Tg = 7 ° C., hereinafter hydran AP) was used.

<Manufacture of U-1>
A reactor equipped with a stirrer, thermometer, nitrogen seal tube, and condenser was charged with 345 parts by mass of polytetramethylene glycol having an average molecular weight of 2000, 77.8 parts by mass of isophorone diisocyanate, and 0.03 parts by mass of dibutyltin dilaurate. , Reacted at 85 ° C. for 2 hours. Subsequently, after cooling this reaction liquid to 50 degreeC, 11.7 mass parts of dimethylpropanolamine, 8.85 mass parts of triethylamine, and 177 mass parts of acetone were added, and it was made to react. Further, 175 parts by mass of acetone was added to the reaction liquid and cooled to 30 ° C., 13.4 parts by mass of isophorone diisocyanate, 1.07 parts by mass of monoethanolamine, 87.9 parts by mass of isopropyl alcohol, and 1039 parts by mass of water. A mixed liquid consisting of parts was added and stirred at high speed, and acetone and IPA were distilled off from this liquid to obtain an aqueous polyether type polyurethane resin dispersion U-1. It was -32 degreeC when Tg of U-1 was measured. Moreover, solid content concentration was 30 mass%.

<Manufacture of U-2>
A reactor equipped with a stirrer, thermometer, nitrogen seal tube, and cooler is charged with 345 parts by mass of polyneopentyl adipate having an average molecular weight of 2000, 77.8 parts by mass of isophorone diisocyanate, and 0.03 parts by mass of dibutyltin dilaurate. , Reacted at 85 ° C. for 2 hours. Subsequently, after cooling this reaction liquid to 50 degreeC, 11.7 mass parts of dimethylpropanolamine, 8.85 mass parts of triethylamine, and 177 mass parts of acetone were added, and it was made to react. Further, 175 parts by mass of acetone was added to the reaction liquid and cooled to 30 ° C., 13.4 parts by mass of isophorone diisocyanate, 1.07 parts by mass of monoethanolamine, 87.9 parts by mass of isopropyl alcohol, and 1039 parts by mass of water. A liquid mixture consisting of parts was added and stirred at high speed, and acetone and IPA were distilled off from this liquid to obtain a polyester-type polyurethane resin aqueous dispersion U-2. It was -29 degreeC when Tg of U-2 was measured. Moreover, solid content concentration was 30 mass%.

[ Reference Example 1]
An aqueous dispersion of HX8290 as a polyolefin resin, KZT-0507 as an aqueous dispersion of a polyester resin, and an aqueous dispersion were mixed so that the resin solid mass ratio was (polyolefin resin) / (polyester resin) = 70/30. .

  The mixture of the obtained aqueous dispersion was reduced in diameter so that the thickness after drying was 0.5 μm on the corona-treated surface of the biaxially stretched polypropylene film raw material (manufactured by Tosero Co., Ltd .: OP U-1 # 20, thickness 20 μm). The coating was performed with a gravure reverse coater (line speed: 15 m / min), and the coated surface was dried at 120 ° C. for 60 seconds. Here, when the paintability of the coated surface after drying was evaluated, no repelling was confirmed.

  A low-density polyethylene resin (Sumitomo Chemical Co., Ltd .: Sumikasen L211, hereinafter referred to as LDPE), which is a sealant resin, is applied to the adhesive layer surface of the biaxially stretched polypropylene film on which the adhesive layer is formed, using an extrusion laminating apparatus equipped with a T die. A 40 μm sealant layer was laminated by melt extrusion at a die temperature of 330 ° C. to obtain a laminated film. The measurement results of the peel strength of the obtained laminated film are shown in Table 2.

[ Reference Examples 2 to 4]
A laminated film was obtained by performing the same operation as in Reference Example 1 except that the mixing ratio of the aqueous dispersion of HX8290 and the mixing ratio of KZT-0507 was changed so that the resin solid content mass ratio as shown in Table 2 was obtained. The measurement results of the peel strength of the obtained laminated film are shown in Table 2.

[ Reference Example 5]
Using an aqueous dispersion of HX8290 as the polyolefin resin and KZT-0507 as the aqueous polyester dispersion, mixing was performed so that the resin solid content mass ratio was (polyolefin resin) / (polyester resin) = 70/30. An aromatic-modified terpene-based tackifier (manufactured by Yashara Chemical, Nanolet R-1050, solid content concentration 50% by mass) as an additive, and a tackifier solid content of 10 with respect to 100 parts by mass of the resin solid content of the obtained mixture. Using the aqueous dispersion added so as to be part by mass, coating and extrusion lamination were performed in the same manner as in Reference Example 1 to obtain a laminated film. The measurement results of the peel strength of the obtained laminated film are shown in Table 2.

[ Reference Example 6]
Using HX8290 as the polyolefin resin and XO-5127 as the polyester resin, dry blending was carried out at a mass ratio of (polyolefin resin) / (polyester resin) = 70/30, and this was mixed with a biaxial kneader (Ikegai PCM) at a temperature of 200 ° C. -30, screw rotation 180 rpm, discharge rate 100 g / min) and kneaded and pelletized with a cutter to obtain a mixed resin. Then, using a pressure-resistant autoclave provided with a stirring blade, 25 parts by mass of melt-kneaded mixed resin, 20 parts by mass of 2-propanol, 0.9 parts by mass of triethylamine and 51 parts by mass of distilled water were charged into the autoclave. After sealing, the stirring blade was stirred at a rotational speed of 100 rpm. Subsequently, the system temperature of the autoclave was heated to 120 ° C., and further stirred for 60 minutes while maintaining 120 ° C. Thereafter, the mixture was cooled to about 40 ° C. while stirring with air cooling at 100 rpm, and then filtered through a 300 mesh stainless steel filter to obtain an aqueous resin dispersion. Using the aqueous dispersion obtained here, coating and extrusion lamination were performed in the same manner as in Reference Example 1 to obtain a laminated film. The measurement results of interlayer adhesion of the obtained laminated film are shown in Table 2.

[ Reference Example 7]
A laminated film was obtained in the same manner as in Reference Example 6 except that UE-3220 was used as the polyester resin. The measurement results of interlayer adhesion of the obtained laminated film are shown in Table 2.

[Examples 1 to 4 ]
Instead of the aqueous dispersion of the polyester resin, a polyether type polyurethane resin aqueous dispersion U-1 is used, and the aqueous dispersion of HX8290 and U-1 are adjusted so as to have a resin solid content mass ratio as shown in Table 2. A laminated film was obtained in the same manner as in Reference Example 1 except that the mixing ratio was changed. The measurement results of the peel strength of the obtained laminated film are shown in Table 2.

[Example 5 ]
An aqueous dispersion of HX8290 was used as the polyolefin resin, and an aqueous dispersion U-1 was used as the polyether-type polyurethane resin, and mixing was performed so that the resin solid content mass ratio was (polyolefin resin) / (polyurethane resin) = 70/30. Aromatically modified terpene tackifier (manufactured by Yashara Chemical, Nanolet R-1050) is added as an additive to 100 parts by mass of the resin solid content of the obtained mixture so that the solid content of the tackifier is 10 parts by mass. Using the obtained aqueous dispersion, coating and extrusion lamination were performed in the same manner as in Reference Example 1 to obtain a laminated film. The measurement results of the peel strength of the obtained laminated film are shown in Table 2.

[ Reference Example 8 ]
A laminated film was obtained by performing the same operation as in Reference Example 1 except that the polyester-type polyurethane resin aqueous dispersion U-2 was used instead of the polyester resin aqueous dispersion. The measurement results of the peel strength of the obtained laminated film are shown in Table-2.

[Example 6 ]
A laminated film was obtained by performing the same operation as in Example 1 except that a polypropylene resin (manufactured by Nippon Polypro Co., Ltd .: Novadic PP FL02A, hereinafter referred to as PP) was used as the sealant resin, and the die temperature during extrusion lamination was set to 300 ° C. Obtained. The measurement results of the peel strength of the obtained laminated film are shown in Table 2.

[Example 7 ]
The same as Example 1 except that an ethylene-vinyl acetate copolymer (Mitsui / DuPont Polychemical Co., Ltd .: EVAFLEX EV550, hereinafter EVA) was used as the sealant resin, and the die temperature during extrusion lamination was 230 ° C. The operation was performed to obtain a laminated film. The measurement results of the peel strength of the obtained laminated film are shown in Table 2.

[Example 8 ]
Example 1 except that an ethylene-ethyl acrylate copolymer (manufactured by Mitsui DuPont Polychemical Co., Ltd .: Everflex EEA A-712, hereinafter referred to as EEA) was used as the sealant resin, and the die temperature at the time of extrusion lamination was 300 ° C. The same operation was performed to obtain a laminated film. The measurement results of the peel strength of the obtained laminated film are shown in Table 2.

[Example 9 ]
A laminated film was obtained in the same manner as in Example 1 except that an unstretched polypropylene film original fabric (manufactured by Tosero Co., Ltd .: CP SC # 30, thickness 30 μm) was used as the polypropylene film. The measurement results of the peel strength of the obtained laminated film are shown in Table 2.

[Example 10 ]
In the same manner as in Example 1 , the aqueous dispersion was adjusted and coated, and a low-density polyethylene film (manufactured by Aicero Chemical Co., Ltd .: Tinlon LS) was used on the adhesive layer surface of the obtained biaxially stretched polypropylene film. -201, thickness 40 μm) was thermocompression bonded at 100 ° C. to laminate a sealant layer to obtain a laminated film. The measurement results of the peel strength of the obtained laminated film are shown in Table 2.

[Comparative Example 1]
A laminated film was obtained by performing the same operation as in Reference Example 1 except that the resin used for the adhesive layer was a polyethyleneimine aqueous solution (Epomin P-1000 manufactured by Nippon Shokubai Co., Ltd., solid content concentration: 30% by mass). The measurement results of the peel strength of the obtained laminated film are shown in Table 3.

[Comparative Example 2]
The same operation as in Reference Example 1 was carried out except that the aqueous dispersion of polyolefin resin HX8290 was used alone. As a result, repelling occurred on the entire coated surface of the biaxially stretched polypropylene film during the coating of the aqueous dispersion. A layer could not be formed. Therefore, the sealant resin was not laminated.

[Comparative Example 3]
A laminated film was obtained in the same manner as in Reference Example 1 except that a 5980I aqueous dispersion was used as the aqueous dispersion of polyolefin resin. The measurement results of the peel strength of the obtained laminated film are shown in Table 3.

[Comparative Example 4]
A laminated film was obtained by performing the same operation as in Reference Example 6 except that UE-3500 was used as the polyester resin. The measurement results of the peel strength of the obtained laminated film are shown in Table 3.

[Comparative Examples 5 to 8]
Instead of the aqueous dispersion of the polyester resin, hydran AP is used as the aqueous dispersion of the polyurethane resin, and the mixing ratio of the aqueous dispersion of HX8290 and the hydran AP is set so that the resin solids mass ratio as shown in Table 3 is obtained. The same operation as in Reference Example 1 was performed except that the change was made. As a result, in Comparative Example 6, cissing occurred on the entire coated surface of the biaxially stretched polypropylene film when the aqueous dispersion was coated, and an adhesive layer could not be formed. Therefore, the sealant resin was not laminated. In Comparative Examples 5, 7, and 8, laminated films were obtained as in Reference Example 1. The measurement results of the peel strength of the obtained laminated film are shown in Table 3.

[Comparative Example 9]
Using an aqueous dispersion of HX8290 as the polyolefin resin and hydran AP as the aqueous dispersion of the polyurethane resin, the mass ratio of resin solids in the aqueous dispersion is (polyolefin resin) / (polyurethane resin) = 70/30 Mixed. To the obtained aqueous dispersion, a melamine-based cross-linking agent (Saimel 327 manufactured by Mitsui Suntex Co., Ltd., solid content concentration: 80% by mass) is added to cross-link to 100 parts by mass of the total solid content of the polyolefin resin and the polyurethane resin. The agent solid content was adjusted to 5 parts by mass. Using the obtained aqueous dispersion, coating and extrusion lamination were performed in the same manner as in Reference Example 1 to obtain a laminated film. The measurement results of the peel strength of the obtained laminated film are shown in Table 3.

[Comparative Example 10]
As shown in Table 3, a laminated film was obtained in the same manner as in Reference Example 1 except that the mixing ratio of the aqueous dispersion of HX8290 and KZT-0507 was changed. The measurement results of the peel strength of the obtained laminated film are shown in Table 3.

From the results of Reference Examples 1 to 8 and Examples 1 to 10 , in the method of providing an adhesive layer on a polypropylene film and laminating a heat seal resin through the adhesive layer, the conventional adhesive layer composition (Comparative Example 1) As a result, it was possible to obtain a laminated film excellent in the peel strength of the polypropylene film / sealant resin.

From the results of Reference Examples 1 to 4, when a mixture of HX8290 and a polyester resin having a Tg of −20 ° C. was used for the adhesive layer, the wettability of the aqueous dispersion was improved as compared with the polyolefin resin alone (Comparative Example 2). It was seen that the film had a high peel strength when the mass ratio was in the range of (A) / (B) = 99/1 to 20/80.

From the result of Reference Example 5, when the tackifier was used as an additive, the peel strength was improved as compared with the case where it was not used ( Reference Example 1).

From the comparison between Reference Examples 1, 6, and 7 and Comparative Example 4, it can be seen that the peel strength is improved by using a polyester resin having a Tg of 5 ° C. or less.

From the results of Examples 1 to 5 and Reference Example 8 , it was confirmed that the peel strength was improved by using polyurethane having a Tg of 5 ° C. or less. When a tackifier was used (Example 5 ), the peel strength was further increased. When polyether type polyurethane was used as the polyurethane (Example 1 ), the peel strength was higher than when polyester type polyurethane was used ( Reference Example 8 ).

From the results of Examples 6 to 8 , it was confirmed that even when a general sealant resin other than LDPE was used, the interlayer adhesion was excellent. When the ethylene-based copolymer was used (Examples 7 and 8 ), the peel strength was higher than when LDPE was used ( Reference Example 1). From the result of Example 9 , even when it was a case where an unstretched film was used as a polypropylene film, high peel strength was shown. From the result of Example 10 , even when the laminating method of the sealant resin was changed from the extrusion laminating method to the dry laminating method, high peel strength was maintained.

  In Comparative Example 1, polyethyleneimine that has been conventionally used as a biaxially oriented polypropylene adhesive layer was used as the adhesive layer, but when it was an LDPE laminate, the peel strength was low and sufficient interlayer adhesion could not be obtained. It was.

  In Comparative Example 2, since an aqueous dispersion of HX8290 was used alone as an adhesive layer and no other thermoplastic resin was mixed, the adhesive layer could not be formed on the polypropylene film due to the problem of wettability.

  In Comparative Example 3, since the structure of the polyolefin resin was different from that defined in the present invention, there was a slight problem with paintability, and sufficient interlayer adhesion was not obtained.

  In Comparative Examples 4 to 9, since a resin having a Tg higher than 5 ° C. was used as the thermoplastic resin to be mixed with the polyolefin resin, there was a slight problem in wettability, and sufficient peel strength was not obtained. Among them, in Comparative Example 6, the effect of adding the polyurethane resin was hardly obtained, and an adhesive layer could not be formed on the polypropylene film due to the problem of paintability. Moreover, although the melamine type crosslinking agent was added in the comparative example 9, there was almost no improvement effect of wettability and peeling strength.

In Comparative Example 10, since the mass ratio of the polyolefin resin (A) and the thermoplastic resin (B) was out of the range defined in the present invention, sufficient peel strength was not obtained.

Claims (4)

In a laminated film in which a sealant layer is laminated on at least one surface of a polypropylene film via an adhesive layer, the adhesive layer contains a (meth) acrylic acid ester component and has an unsaturated carboxylic acid component amount of 0.01 to 5. Including a mixture of 0% by mass of acid-modified polyolefin resin (A) and polyether type polyurethane resin (B) having a glass transition temperature of 5 ° C. or less, the mass ratio (A) / (B) is 99/1 to Laminated film in the range of 20/80. The laminated film of claim 1 Symbol placing sealant resin is a polyethylene resin and / or polypropylene resin. An aqueous dispersion containing the resin solid content of the polyolefin resin (A) and the polyether type polyurethane resin (B) in a mass ratio (A) / (B) = 99/1 to 20/80 is at least included in the polypropylene film. The method for producing a laminated film according to claim 1 or 2 , wherein the adhesive layer is formed by applying to one side and then drying, and then a sealant resin is laminated via the adhesive layer. 4. The method for producing a laminated film according to claim 3, wherein the sealant resin is laminated by extrusion lamination.