Anti-fogging multi-layer film, laminate using same, and packaging material

Abstract

Provided is a multi-layer film comprising a seal layer (A) and a resin layer (B) that is adjacent to the seal layer (A), wherein the seal layer (A) contains a polyester-based resin (a) and an anti-fogging agent, and the resin layer (B) contains an acid-modified polyolefin and a polyester-based resin (b). Also provided are a laminate, a packaging material, and a food packaging container. It is preferable that the seal layer contains a polyester-based resin (a1) and a polyester-based resin (a2) as the polyester-based resin, the glass transition temperature of the polyester-based resin (a1) is 60-140°C, and the glass transition temperature of the polyester-based resin (a2) is not higher than 45°C.

Description

Anti-fogging multilayer film, laminate using the same, and packaging material

[0001] The present invention relates to a multilayer film that has both anti-fogging properties and easy-open properties and can be suitably used as a lid material for food packaging containers, and a laminate using the same.

[0002] Polyester containers, which have excellent transparency and recyclability, have traditionally been widely used as packaging for chilled foods such as cut vegetables and fruits. The lids of these containers are required to have anti-fogging properties to improve the visibility of the contents. This is because if the inner surface of the packaging material becomes cloudy due to moisture evaporation from the chilled food inside the container, the contents become difficult to see, reducing the product value and failing to meet consumer demands for food safety and security. Furthermore, while it is essential for container lids to have a reliable seal until the contents are removed, the trend toward universal design has placed importance on methods that are easy for consumers to open, such as easy-opening, as a consideration for socially vulnerable people (e.g., the elderly, young children, and people with disabilities).

[0003] Currently, known methods for imparting anti-fogging properties to packaging materials include a method in which a resin is formed into a film and then an anti-fogging agent is applied to the surface that comes into contact with the contents (see, for example, Patent Document 1), and a method in which an anti-fogging agent is kneaded into a resin used for the packaging material, which is then formed into a film and then secondary molded for use in various packaging materials.

[0004] The method of applying a coating liquid containing an anti-fogging agent to the surface of a film requires a step of applying the coating liquid containing the anti-fogging agent and a step of drying the coating film, which results in low production efficiency. Furthermore, there is a problem that the anti-fogging agent on the coated surface is washed away by evaporation of water from the contents, thereby reducing the durability of the anti-fogging effect.

[0005] In addition, when an anti-fog agent is kneaded into a resin by kneading the anti-fog agent into all layers of a single-layer film or a multilayer film, when the surface is printed or laminated to another substrate film, the anti-fog agent bleeds out onto the surface and acts on the printing ink or adhesive, which can cause peeling of the printed surface or poor adhesion. On the other hand, in a method of kneading an anti-fog agent into a sealing layer (A) of a multilayer film (see, for example, Patent Document 2), the anti-fog agent has the property of easily moving within the multilayer film, so the anti-fog effect is not constant and there are concerns about the durability of the effect. Furthermore, the migration of the anti-fog agent to a layer adjacent to the layer containing the anti-fog agent can reduce the adhesion between layers, potentially causing deterioration in film tearability.

[0006] In response to these problems, the applicants conducted research and found that a film having an antifogging agent in a heat seal layer and having an adjusted free volume pore size and rigidity of the heat seal layer can suppress deterioration of film tearability over time, leading to the completion of the invention of Patent Document 3. The present invention was developed to achieve both better film tearability and antifogging properties, and to achieve improved seal strength.

[0007] JP 2004-025825 A JP 2019-171792 A WO2023 / 063091 A

[0008] In view of the above circumstances, an object of the present invention is to provide a multilayer film that has good film tearability and excellent easy-open properties, is particularly excellent in anti-fogging properties that prevent fogging due to water vapor from the contents, and has good seal strength, and is suitable for use as a lid material for packaging containers, etc.; a laminate obtained by laminating this multilayer film onto a base film; and a packaging material using the same.

[0009] As a result of intensive research conducted by the present inventors to solve the above problems, they found that the above problems can be solved by a multilayer film comprising a sealing layer (A) and a resin layer (B) adjacent to the sealing layer (A), wherein the sealing layer (A) contains a polyester-based resin (a) and an anti-fogging agent, and the resin layer (B) contains an acid-modified polyolefin and a polyester-based resin (b), and thus completed the present invention.

[0010] That is, the present invention provides the following multilayer films, packaging materials, and food packaging containers (1) to (10). (1) A multilayer film comprising a sealing layer (A) and a resin layer (B) adjacent to the sealing layer (A), wherein the sealing layer (A) comprises a polyester-based resin (a) and an antifogging agent, and the resin layer (B) comprises an acid-modified polyolefin and a polyester-based resin (b). (2) The multilayer film according to (1), wherein the sealing layer comprises polyester-based resins (a1) and (a2) as polyester-based resins, wherein the polyester-based resin (a1) has a glass transition temperature of 60 to 140°C and the polyester-based resin (a2) has a glass transition temperature of 45°C or lower. (3) The multilayer film according to (1), wherein the polyester-based resin (b) has a glass transition temperature of 45°C or lower. (4) The multilayer film according to (1), wherein the amount of the antifogging agent in the sealing layer (A) is 1.0 to 7.0% by mass. (5) The multilayer film according to (1), wherein the mass ratio of the acid-modified polyolefin to the polyester-based resin (b) in the resin layer (B) is 45:55 to 95:5. (6) The multilayer film according to (1), wherein the multilayer film further comprises a laminate layer (A). (7) A laminate having the multilayer film according to any one of (1) to (6). (8) A packaging material using the laminate according to (7). (9) The packaging material according to (8), which is a lid material for a food packaging container. (10) A food packaging container using the packaging material according to (9) as a lid material, wherein the portion of the food packaging container that is to be adhered to the lid material contains a polyester-based resin.

[0011] The multilayer film and the laminate using the same of the present invention, when used as a lid material for a polyester packaging container or when sealed in the form of a bag, exhibit excellent ease of opening without film tearing when opened, since the sealing layer (A) is firmly heat-sealed to the polyester packaging container or polyester film. In addition, since the anti-fogging properties are particularly good, the multilayer film and the laminate using the same can be suitably used as packaging materials for chilled foods such as fresh produce and prepared foods.

[0012] The multilayer film of the present invention and each of the components constituting the laminate using the same will be described in detail below.

[0013] <Sealing layer (A)> In the multilayer film of the present invention, the sealing layer (A) contains a polyester resin (a) and an antifogging agent. The sealing layer (A) constitutes a surface layer on one side of the multilayer film and laminate of the present invention and is a layer that seals the sealing surface of a polyester packaging container. The sealing layer (A) also has an antifogging function and can turn water droplets adhering to the surface of the multilayer film and laminate facing the inside of the container into a water film, thereby reducing fogging caused by water vapor from the contents and improving the visibility of the contents.

[0014] <Anti-fogging agent> The sealing layer (A) used in the present invention contains an anti-fogging agent. The anti-fogging agent is not particularly limited as long as it is generally known to impart anti-fogging properties, and for example, anionic surfactants, nonionic surfactants, cationic surfactants, amphoteric surfactants, etc. can be used. Among these, it is preferable to use nonionic surfactants.

[0015] Specific examples of the nonionic surfactants include sorbitan surfactants such as sorbitan monostearate, sorbitan distearate, sorbitan monopalmitate, sorbitan dipalmitate, sorbitan monobehenate, sorbitan dibehenate, sorbitan monolaurate, and sorbitan dilaurate; glycerin surfactants such as glycerin monolaurate, glycerin dilaurate, diglycerin monopalmitate, diglycerin dipalmitate, glycerin monostearate, glycerin distearate, diglycerin monostearate, diglycerin distearate, diglycerin monolaurate, and diglycerin dilaurate; polyethylene glycol monostearate, polyethylene glycol dilau ... Examples of suitable surfactants include polyethylene glycol surfactants such as polyethylene glycol monopalmitate; trimethylolpropane surfactants such as trimethylolpropane monostearate; diethanolalkylamine and diethanolalkylamide surfactants such as lauryl diethanolamine, oleyl diethanolamine, stearyl diethanolamine, lauryl diethanolamide, oleyl diethanolamide, and stearyl diethanolamide; pentaerythritol surfactants such as pentaerythritol monopalmitate; polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan distearate, and mono- and distearates of sorbitan-diglycerin condensates. These surfactants may be used alone or in combination of two or more. Glycerin surfactants are particularly preferred.

[0016] The lower limit of the proportion of the antifogging agent in the sealing layer (A) used in the present invention is preferably 0.5% by mass or more, more preferably 1.0% by mass or more, based on the total mass of the layer. Using an antifogging agent within this range facilitates the antifogging properties. The upper limit of the proportion is preferably 7.0% by mass or less, more preferably 5.0% by mass or less, and even more preferably 4.0% by mass or less, based on the total mass of the sealing layer (A). Using an antifogging agent within this range reduces the risk of excessive migration of the antifogging agent to layers in contact with the sealing layer (A), thereby suppressing a decrease in interlayer strength. That is, the amount of antifogging agent in the sealing layer (A) is preferably 0.5 to 7.0% by mass, more preferably 1.0 to 7.0% by mass, even more preferably 1.0 to 5.0% by mass, and particularly preferably 1.0 to 4.0% by mass.

[0017] <Polyester-based resin (a)> The sealing layer (A) used in the present invention contains a polyester-based resin (a). The polyester resin (a) contains, as a polyvalent carboxylic acid component, a component selected from phthalic acid, terephthalic acid, isophthalic acid, orthophthalic acid, adipic acid, sebacic acid, naphthalenedicarboxylic acid, 4,4'-diphenylsulfonedicarboxylic acid, 4,4'-biphenyldicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,3-phenylenedioxydiacetic acid, and structural isomers thereof, dicarboxylic acids such as malonic acid, succinic acid, and adipic acid, or derivatives thereof, p-hydroxybenzoic acid, p-hydroxybenzoic acid esters, and oxyacids such as glycolic acid, or derivatives thereof, and a polyhydric alcohol component selected from ethylene glycol, diethylene glycol, propylene glycol, 2-methyl-1,3-propanediol, 2,2-dimethyltrimethylene glycol, 1,4-butanediol, 1,5-pentanediol, 3-methylpentanediol, 1,6-hexanediol, and the like. and a component selected from polyhydric alcohols such as 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-dodecanediol, 1,16-hexadecanediol, 1,18-octadecanediol, 1,20-icosanediol, 1,4-cyclohexanedimethanol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polytetramethylene ether glycol, neopentyl glycol, pentaethylene glycol, and trimethylolpropane, alicyclic glycols such as isosorbide, and aromatic dihydroxy compound derivatives such as bisphenol A and bisphenol S. One or more components are selected and combined from the group consisting of a dibasic acid component and a glycol component, and a transesterification reaction or esterification reaction is carried out, followed by a melt polycondensation reaction.

[0018] From the viewpoint of exhibiting sealing properties with polyester-based packaging containers, the sealing layer (A) used in the present invention preferably contains the polyester-based resin (a) in an amount of 90 mass% or more relative to the total amount of resin components forming the sealing layer (A).

[0019] The polyester resin (a) may be used alone or in combination with a plurality of types. Among these, it is preferable to use a polyester resin (a1) having a glass transition temperature of 60 to 140°C in combination with a polyester resin (a2) having a glass transition temperature of 45°C or lower as the polyester resin (a). The combined use of the polyester resin (a1) and the polyester resin (a2) facilitates the performance of the anti-fogging agent, and facilitates compatibility with seal strength. The glass transition temperature (Tg) of the polyester resin (a) is a value determined by a method conforming to Japanese Industrial Standards (JIS K7121), i.e., differential scanning calorimetry (DSC).

[0020] (Polyester-based resin (a1)) The polyester-based resin (a1) is a polyester-based resin (a) having a glass transition temperature of 60 to 140° C. The polyester-based resin (a1) is obtained by polycondensation of a polycarboxylic acid and a polyhydric alcohol.

[0021] Examples of the polycarboxylic acid include malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, hexahydrophthalic acid, 1,4-cyclohexanedicarboxylic acid, maleic acid, maleic anhydride, citraconic acid, dimethylmaleic acid, cyclopentene-1,2-dicarboxylic acid, 1-cyclohexene-1,2-dicarboxylic acid, 4-cyclohexene-1,2-dicarboxylic acid, fumaric acid, mesaconic acid, itaconic acid, glutaconic acid, phthalic acid, phthalic anhydride, terephthalic acid, isophthalic acid, orthophthalic acid, 1,2,5-hexanetricarboxylic acid, 1,2,4-cyclohexanetricarboxylic acid, trimellitic acid, trimellitic anhydride, 1,2,5-benzenetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid, pyromellitic acid, pyromellitic anhydride, etc. These may be used alone or in combination of two or more. Furthermore, if necessary, monocarboxylic acids such as methanoic acid, ethanoic acid, propanoic acid, butanoic acid, pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, dodecanoic acid, tetradecanoic acid, hexadecanoic acid, heptadecanoic acid, and octadecanoic acid may be used as raw material components.

[0022] Examples of the polyhydric alcohol include ethylene glycol, diethylene glycol, propylene glycol, 2-methyl-1,3-propanediol, 2,2-dimethyltrimethylene glycol, 1,4-butanediol, 1,5-pentanediol, 3-methylpentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-dodecanediol, 1,16-hexadecanediol, 1,18-octadecanediol, 1,20-icosanediol, 1,4-cyclohexanedimethanol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polytetramethylene ether glycol, neopentyl glycol, pentaethylene glycol, isosorbide, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, and trimethylolpropane. These may be used alone or in combination of two or more.

[0023] The polycarboxylic acids and polyhydric alcohols may be used in any combination, and specific examples thereof include terephthalic acid / ethylene glycol / neopentyl glycol copolymer, terephthalic acid / ethylene glycol / 1,4-cyclohexanedimethanol / isosorbide copolymer, terephthalic acid / isophthalic acid / ethylene glycol copolymer, terephthalic acid / ethylene glycol / 1,4-cyclohexanedimethanol copolymer, and terephthalic acid / 1,4-cyclohexanedimethanol / 2,2,4,4-tetramethyl-1,3-cyclobutanediol copolymer.

[0024] The glass transition temperature of the polyester resin (a1) is 60 to 140°C, preferably 60 to 130°C, and more preferably 60 to 120°C. By using a polyester resin (a1) with such a glass transition temperature, favorable film processability and heat resistance can be ensured. Examples of such polyester resin (a1) include, but are not limited to, resins commercially available under the trade name "ECOZEN" (SK Chemicals).

[0025] (Polyester-based resin (a2)) The polyester-based resin (a2) is a polyester-based resin (a) having a glass transition temperature of 45° C. or lower. The polyester-based resin (a2) is obtained by polycondensation of a polycarboxylic acid and a polyhydric alcohol.

[0026] Examples of the polycarboxylic acid include aromatic polycarboxylic acids such as phthalic acid, phthalic anhydride, terephthalic acid, isophthalic acid, orthophthalic acid, naphthalenedicarboxylic acid, and trimellitic acid, as well as aliphatic polycarboxylic acids such as succinic acid, adipic acid, azelaic acid, sebacic acid, decanoic acid, undecanediacid, dodecanediacid, tridecanediacid, tetradecanediacid, heptadecanedioic acid, hexadecanedioic acid, heptadecanedioic acid, octadecanedioic acid, dimer acid, and cyclohexanedicarboxylic acid. These may be used alone or in combination of two or more. Furthermore, if necessary, monocarboxylic acids such as methanoic acid, ethanoic acid, propanoic acid, butanoic acid, pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, dodecanoic acid, tetradecanoic acid, hexadecanoic acid, heptadecanoic acid, and octadecanoic acid may also be used as raw material components.

[0027] Examples of the polyhydric alcohol include ethylene glycol, diethylene glycol, propylene glycol, 2-methyl-1,3-propanediol, 2,2-dimethyltrimethylene glycol, 1,4-butanediol, 1,5-pentanediol, 3-methylpentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-dodecanediol, 1,16-hexadecanediol, 1,18-octadecanediol, 1,20-icosanediol, 1,4-cyclohexanedimethanol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polytetramethylene ether glycol, neopentyl glycol, pentaethylene glycol, and trimethylolpropane. These may be used alone or in combination of two or more.

[0028] The polycarboxylic acids and polyhydric alcohols may be used in any combination. Specific examples include terephthalic acid / ethylene glycol copolymer, terephthalic acid / 1,4-butanediol copolymer, terephthalic acid / adipic acid / 1,4-butanediol copolymer, terephthalic acid / polytetramethylene ether glycol / 1,4-butanediol copolymer, terephthalic acid / isophthalic acid / 1,4-butanediol / polytetramethylene ether glycol copolymer, terephthalic acid / isophthalic acid / 1,4-butanediol copolymer, and terephthalic acid / isophthalic acid / 1,4-butanediol / polytetramethylene ether glycol / 1,4-butanediol copolymer.

[0029] The glass transition temperature of the polyester resin (a2) is 45°C or lower, preferably -80 to 40°C, more preferably -80 to 0°C, and even more preferably -80 to -20°C. By using a polyester resin (a2) with such a glass transition temperature, the function of the antifogging agent can be easily exerted, and it becomes easy to achieve compatibility with seal strength. Examples of such polyester resin (a2) include, but are not limited to, resins commercially available under the trade name "Vylon" (Toyobo Co., Ltd.).

[0030] In the seal layer (A) of the present invention, when a polyester resin (a1) having a glass transition temperature of 60 to 140°C and a polyester resin (a2) having a glass transition temperature of 45°C or lower are used in combination as the polyester resin (a), the total content of the polyester resin (a1) and the polyester resin (a2) in the seal layer (A) is preferably 70% by mass or more in terms of obtaining favorable heat sealability and heat resistance. Furthermore, in terms of obtaining favorable film appearance, it is more preferably 75% by mass or more, and even more preferably 80% by mass or more. The upper limit of this content is not particularly limited, but is preferably 99% by mass or less, and more preferably 97% by mass or less.

[0031] The content of the polyester resin (a1) in the seal layer of the present invention is preferably 20 to 90% by mass, more preferably 30 to 80% by mass, and even more preferably 50 to 70% by mass. The content of the polyester resin (a2) in the seal layer of the present invention is preferably 10 to 80% by mass, more preferably 20 to 70% by mass, and even more preferably 30 to 50% by mass. This content range is preferable because it allows for both anti-fogging properties and heat sealability.

[0032] The content ratio of the polyester resin (a1) to the polyester resin (a2) is preferably 20:80 to 90:10, more preferably 30:70 to 80:20, and even more preferably 50:50 to 70:30. When the content ratio is within this range, the function of the antifogging agent is easily exhibited, and both antifogging properties and film tearability can be achieved, and transparency is also improved.

[0033] The polyester resin (a) in the sealing layer (A) used in the present invention may be a biodegradable polyester. Examples of biodegradable polyesters include polyhydroxyalkanoates such as polylactic acid resins, poly(butylene succinate) (PBS), poly(butylene succinate / adipate) copolymer (PBSA), poly(3-hydroxybutyric acid), copolymers of 3-hydroxybutyric acid and 3-hydroxyvaleric acid, and copolymers of 3-hydroxybutyric acid and 4-hydroxybutyric acid; aliphatic polyester compounds such as polyglycolic acid, polycaprolactone, and ring-opening polymers such as β-propiolactone and γ-valerolactone; polyesters composed of aliphatic dibasic acids and aliphatic diols, such as copolyesters of adipic acid, 1,4-butanediol, and terephthalic acid (polybutylene adipate terephthalate), polyesters composed of succinic acid and ethylene glycol (polyethylene succinate); copolymers of aromatic polyesters and aliphatic polyesters; and copolymers of aliphatic polyesters and polyamides. The composition may further contain other biodegradable resins such as polyvinyl alcohol, pullulan, chitosan, curdlan, starch-based green plastics, esterified starch, cellulose, and cellulose acetate.

[0034] The resin constituting the sealing layer (A) in the present invention may be used in combination with other resins as long as the sealing property and anti-fogging property are not impaired. From the viewpoint of exhibiting sealing property with a polyester-based packaging container, the content of the other resins in the sealing layer (A) is preferably 10% by mass or less, more preferably 5% by mass or less, and more preferably no other resins are contained, based on the total amount of the resin components constituting the sealing layer (A).

[0035] Examples of the other resins include polyolefin resins such as ethylene resins, propylene resins, and cyclic olefin resins; thermoplastic elastomers such as polyethylene elastomers, polypropylene elastomers, and butene elastomers; ethylene copolymers such as ethylene-vinyl acetate copolymer (EVA), ethylene-methyl methacrylate copolymer (EMMA), ethylene-ethyl acrylate copolymer (EEA), ethylene-methyl acrylate (EMA) copolymer, ethylene-ethyl acrylate-maleic anhydride copolymer (E-EA-MAH), ethylene-acrylic acid copolymer (EAA), and ethylene-methacrylic acid copolymer (EMAA); and further ionomers of ethylene-acrylic acid copolymers, ionomers of ethylene-methacrylic acid copolymers, and other biodegradable resins mentioned above. Examples of ethylene-based resins include polyethylene resins such as very low density polyethylene (VLDPE), linear low density polyethylene (LLDPE), low density polyethylene (LDPE), linear medium density polyethylene (LMDPE), medium density polyethylene (MDPE), and high density polyethylene (HDPE). Examples of propylene-based resins include propylene homopolymers, propylene-α-olefin random copolymers such as propylene-ethylene butene-1 copolymers, and propylene block copolymers such as propylene-α-olefin block copolymers. Examples of cyclic olefin-based resins include norbornene polymers, vinyl alicyclic hydrocarbon polymers, and cyclic conjugated diene polymers. Among these, norbornene polymers are preferred. Examples of norbornene polymers include ring-opening polymers of norbornene monomers (hereinafter sometimes referred to as "COP") and norbornene copolymers (hereinafter sometimes referred to as "COC") obtained by copolymerizing norbornene monomers with olefins such as ethylene.

[0036] The sealing layer (A) used in the present invention can contain components such as antistatic agents, heat stabilizers, nucleating agents, antioxidants, lubricants, antiblocking agents, release agents, UV absorbers, colorants, and biodegradable agents, provided that the object of the present invention is not impaired. In particular, to ensure processability during multilayer film molding and packaging suitability for filling machines, the coefficient of friction of the multilayer film surface is preferably 2.0 or less, and more preferably 1.5 or less. Therefore, it is preferable to appropriately add lubricants, antiblocking agents, and antistatic agents to the sealing layer (A), which serves as the surface layer of the multilayer film of the present invention. The additives such as lubricants and antiblocking agents are not particularly limited, and commercially available ones can be used.

[0037] <Resin Layer (B)> The resin layer (B) of the present invention is a layer adjacent to the sealing layer (A), and contains an acid-modified polyolefin and a polyester-based resin (b).

[0038] <Acid-Modified Polyolefin> The resin layer (B) of the present invention contains an acid-modified polyolefin. The olefin component constituting the main chain of the acid-modified polyolefin is not particularly limited, but is preferably an alkene having 2 to 6 carbon atoms, such as ethylene, propylene, isobutylene, 2-butene, 1-butene, 1-pentene, or 1-hexene, or a mixture thereof may be used. Among these, an alkene having 2 to 4 carbon atoms, such as ethylene, propylene, isobutylene, or 1-butene, is more preferred, ethylene or propylene is even more preferred, and ethylene is most preferred.

[0039] The acid-modified polyolefin also contains a (meth)acrylic acid ester component. Examples of the (meth)acrylic acid ester component include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, hexyl (meth)acrylate, octyl (meth)acrylate, decyl (meth)acrylate, lauryl (meth)acrylate, octyl (meth)acrylate, dodecyl (meth)acrylate, and stearyl (meth)acrylate. From the standpoints of availability and adhesiveness, methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, and hexyl acrylate are more preferred, and methyl acrylate and ethyl acrylate are more preferred. The (meth)acrylic acid ester component may be copolymerized with the olefin component, and the form of the copolymerization is not limited. Examples of the copolymerization state include random copolymerization, block copolymerization, and graft copolymerization (graft modification). (Note that "(meth)acrylic acid..." means "acrylic acid... or methacrylic acid...".) Specific examples of ethylene-(meth)acrylic acid ester copolymers include Elvaloy (trade name: manufactured by DuPont-Mitsui Polychemicals Co., Ltd.) and Acryft (trade name: manufactured by Sumitomo Chemical Co., Ltd.). These may be used alone or in combination of two or more.

[0040] The acid-modified polyolefin may also be acid-modified with an unsaturated carboxylic acid component. Examples of unsaturated carboxylic acid components include acrylic acid, methacrylic acid, maleic acid, maleic anhydride, itaconic acid, itaconic anhydride, fumaric acid, and crotonic acid, as well as half esters and half amides of unsaturated dicarboxylic acids. Among these, acrylic acid, methacrylic acid, maleic acid, and maleic anhydride are preferred, with acrylic acid and maleic anhydride being particularly preferred. The unsaturated carboxylic acid component may be copolymerized with the olefin component in any form, and examples of the copolymerization state include random copolymerization, block copolymerization, and graft copolymerization (graft modification). Specific examples of ethylene-acrylic acid copolymers include Nucrel (trade name: manufactured by DuPont-Mitsui Polychemicals Co., Ltd.). Examples of ethylene-(meth)acrylic acid ester-maleic anhydride copolymers include Bondine (trade name: manufactured by Arkema). These copolymers may be used alone or in combination of two or more.

[0041] The acid-modified polyolefin preferably has an acid modification rate of 0.5 to 40%, more preferably 0.5 to 35%, and particularly preferably 0.5 to 30%, from the viewpoint of good adhesiveness.

[0042] The resin layer (B) in the present invention preferably contains the acid-modified polyolefin in an amount of 40 to 95% by mass, more preferably 51 to 95% by mass, and even more preferably 55 to 90% by mass. By setting the content of the acid-modified polyolefin within this range, sufficient interlayer strength between the seal layer (A) and the resin layer (B) can be obtained.

[0043] <Polyester-based resin (b)> In the resin layer (B) of the present invention, a polyester-based resin (b) is used in combination with the acid-modified polyolefin. The combined use of the acid-modified polyolefin and the polyester-based resin (b) significantly improves the interlayer strength between the antifogging agent-containing seal layer (A) and the resin layer (B) without impairing transparency, thereby improving film tearability. Generally, acid-modified polyolefins are known as adhesive resins and have been used to bond different resin layers (e.g., polyester-based resin layers and polyolefin resin layers). Therefore, it has been thought that the use of another resin in combination with an acid-modified polyolefin would result in a decrease in interlayer adhesion. However, in the present invention, it has been discovered that the use of the resin layer (B) as described above has the effect of suppressing the adhesion inhibition caused by the antifogging component, particularly in the interlayer adhesion between the antifogging agent-containing polyester-based seal layer and a different resin layer.

[0044] The polyester resin (b) may be the same as the polyester resin (a) described above. However, it is preferable to use a polyester resin (b) having a glass transition temperature of 45°C or less, and the same resin as the polyester resin (a2) described above can be used. The use of a polyester resin (b) having a glass transition temperature of 45°C or less improves interlayer adhesion even in the presence of an antifogging agent, thereby allowing for an increased amount of antifogging agent in the sealing layer and improving antifogging properties. Biodegradable polyesters may also be used. The polyester resin (b) is preferably a polyester resin (b) obtained by polycondensing a low-molecular-weight polyhydric alcohol having a molecular weight of 2000 or less with a polycarboxylic acid. The glass transition temperature of the polyester resin (b) is preferably 45°C or less, more preferably -80 to 40°C, even more preferably -80 to 0°C, and particularly preferably -80 to -20°C.

[0045] The content of the polyester resin (b) in the resin layer (B) of the present invention is preferably 5 to 60% by mass, more preferably 5 to 49% by mass, and even more preferably 10 to 45% by mass.

[0046] The mass ratio of the acid-modified polyolefin to the polyester resin (b) in the resin layer (B) of the present invention is preferably 30:70 to 95:5, more preferably 40:60 to 95:5, and even more preferably 45:55 to 95:5. When the mass ratio is within this range, the interlayer strength is improved, which tends to improve film tearability.

[0047] Components such as antistatic agents, heat stabilizers, nucleating agents, antioxidants, lubricants, antiblocking agents, release agents, ultraviolet absorbers, colorants, and biodegradable agents may also be added to the resin layer (B) as long as the object of the present invention is not impaired.

[0048] (Other Layers) The multilayer film of the present invention may contain layers other than the seal layer (A) and the resin layer (B). The other layers may be, but are not limited to, polyester-based resin layers, polyolefin-based resin layers, etc., and are preferably polyolefin resin layers. It is also preferable that the other layers include two or more polyolefin resin layers. In this case, the layer that constitutes the other surface of the multilayer film of the present invention other than the seal layer (A) is referred to as the "laminate layer," and the layer located between the laminate layer and the resin layer (B) is referred to as the "intermediate layer."

[0049] (Polyolefin-Based Resin Layer) The multilayer film of the present invention preferably includes two or more polyolefin-based resin layers in addition to the above-mentioned seal layer (A) and resin layer (B).

[0050] Examples of the polyolefin resin include, but are not limited to, ethylene resin, propylene resin, and cyclic olefin resin. The resin that serves as the main component of each layer may be appropriately selected depending on the properties required for each layer of the multilayer film.

[0051] Examples of the ethylene-based resin include low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), medium-density polyethylene (MDPE), and high-density polyethylene (HDPE), which may be used alone or in combination. Among these, linear low-density polyethylene is preferred.

[0052] The low density polyethylene (LDPE) is 0.935 g / cm ３ By "ethylene" is meant a homopolymer of ethylene having a density less than 1000 MPa.

[0053] The linear low-density polyethylene is obtained by copolymerizing ethylene monomer as a main component with an α-olefin such as butene-1, hexene-1, octene-1, or 4-methylpentene as a comonomer by a low-pressure radical polymerization method using a multi-site catalyst or a single-site catalyst typified by a Ziegler-Natta catalyst, and has a density of 0.925 g / cm ３ It refers to a linear low-density polyethylene having a comonomer content of less than 100 mol %. Therefore, it is distinguished from low-density polyethylene (LDPE), which is a homopolymer of ethylene. The comonomer content in linear low-density polyethylene is preferably in the range of 0.5 to 20 mol %, and more preferably in the range of 1 to 18 mol %. The use of butene-1 as the comonomer is preferred because it improves transparency, impact resistance, tearability, etc., and in this case, the butene monomer content is most preferably in the range of 1 to 5 mol %.

[0054] Examples of the single-site catalyst include various single-site catalysts, such as metallocene catalyst systems that combine a metallocene compound of a transition metal of Group IV or V of the periodic table with an organoaluminum compound and / or an ionic compound. Single-site catalysts have uniform active sites, and therefore, compared with multi-site catalysts with non-uniform active sites, the molecular weight distribution of the resulting resin is sharper, resulting in less precipitation of low-molecular-weight components when formed into a film, and in a resin with excellent physical properties such as stable seal strength and excellent blocking resistance.

[0055] The medium density polyethylene (MDPE) is 0.925 g / cm ３ 0.942g / cm or more ３ It means a copolymer of ethylene and an α-olefin having a density of less than 1000 kJ / mol. Since the density decreases as the α-olefin used as the comonomer increases, the amount of comonomer is preferably small, and specifically, the comonomer ratio is preferably 0.5 to 1%, but is not limited to this range.

[0056] The high density polyethylene (HDPE) has a density of 0.942 g / cm ３ The term "polyethylene" refers to a polyethylene having a density of at least 100%. It may be a homopolymer of ethylene or a copolymer of ethylene and an α-olefin, but since the density decreases as the amount of α-olefin used as a comonomer increases, it is preferable that the amount of comonomer is small, and specifically, the comonomer ratio is preferably 0.5% or less.

[0057] In some cases, the comonomer ratio is not disclosed for commercially available products, so linear low-density polyethylene, medium-density polyethylene, and high-density polyethylene are distinguished by density, and low-density polyethylene and medium-density polyethylene are distinguished by whether they are ethylene homopolymers or not. In the present invention, even if a product is commercially available as linear low-density polyethylene, if the density is 0.925 g / cm ３ The above may be treated as medium density polyethylene. ３ If there is a polyethylene of this type, if it is an ethylene homopolymer it should be treated as low-density polyethylene, and if it is an ethylene and α-olefin copolymer it should be treated as medium-density polyethylene.

[0058] Furthermore, biomass-derived polyethylene may be used as the ethylene-based resin, for example, biomass-derived low-density polyethylene (product name: SBC818, density: 0.918 g / cm) manufactured by Braskem. ３ , MFR: 8.1 g / 10 min), and biomass-derived low-density polyethylene manufactured by Braskem (trade name: SPB681, density: 0.922 g / cm ３ , MFR: 3.8 g / 10 min), and biomass-derived linear low-density polyethylene manufactured by Braskem (trade name: SLL118, density: 0.916 g / cm ３ , MFR: 1.0 g / 10 min).

[0059] Furthermore, the ethylene-based resin may be mixed with an ethylene-based copolymer such as ethylene-vinyl acetate copolymer (EVA), ethylene-methyl methacrylate copolymer (EMMA), ethylene-ethyl acrylate copolymer (EEA), ethylene-methyl acrylate (EMA) copolymer, ethylene-ethyl acrylate-maleic anhydride copolymer (E-EA-MAH), ethylene-acrylic acid copolymer (EAA), or ethylene-methacrylic acid copolymer (EMAA); or further with an ionomer of an ethylene-acrylic acid copolymer, an ionomer of an ethylene-methacrylic acid copolymer, or the like.

[0060] Examples of the propylene-based resin include propylene homopolymer, propylene-ethylene copolymer, propylene-butene-1 copolymer, propylene-ethylene-butene-1 copolymer, metallocene catalyst polypropylene, etc. These may be used alone or in combination. In particular, using a propylene-based copolymer as the polypropylene-based resin is preferred because it is easy to obtain seal strength. When the polypropylene-based resin is used in the seal layer used in the present invention, the heat resistance of the film is improved and the heat seal strength can be increased, making it particularly suitable for use as a packaging material for heavy goods.

[0061] Examples of the cyclic olefin resin include norbornene polymers, vinyl alicyclic hydrocarbon polymers, and cyclic conjugated diene polymers. Among these, norbornene polymers are preferred. Norbornene polymers include ring-opening polymers of norbornene monomers (hereinafter sometimes referred to as "COP") and norbornene copolymers (hereinafter sometimes referred to as "COC") obtained by copolymerizing norbornene monomers with olefins such as ethylene. Hydrogenated products of COP and COC are particularly preferred. The weight-average molecular weight of the cyclic olefin resin is preferably 5,000 to 500,000, more preferably 7,000 to 300,000.

[0062] The norbornene-based polymer and the norbornene-based monomer used as a raw material are alicyclic monomers having a norbornene ring. Examples of such norbornene-based monomers include norbornene, tetracyclododecene, ethylidenenorbornene, vinylnorbornene, ethylidetetracyclododecene, dicyclopentadiene, dimethanotetrahydrofluorene, phenylnorbornene, methoxycarbonylnorbornene, and methoxycarbonyltetracyclododecene. These norbornene-based monomers may be used alone or in combination of two or more.

[0063] The norbornene copolymer (COC) is a copolymer of the norbornene monomer and a copolymerizable olefin, and examples of such olefins include olefins having 2 to 20 carbon atoms such as ethylene, propylene, and 1-butene; cycloolefins such as cyclobutene, cyclopentene, and cyclohexene; and non-conjugated dienes such as 1,4-hexadiene. These olefins can be used alone or in combination of two or more.

[0064] The content of the norbornene monomer in the norbornene copolymer (COC) is preferably 40 to 90 mol %, more preferably 50 to 80 mol %. When the content is in this range, the rigidity, tearability, and processing stability of the film are improved.

[0065] Commercially available products that can be used as the cyclic olefin resin include, for example, "ZEONOR" manufactured by Zeon Corporation as a ring-opening polymer (COP) of a norbornene monomer, and "APEL" manufactured by Mitsui Chemicals, Inc. and "TOPAS" manufactured by TICONA as a norbornene copolymer (COC).

[0066] (Laminate layer) The multilayer film of the present invention preferably includes a laminate layer. The laminate layer is a layer mainly composed of a polyolefin resin, and as described above, is a layer that constitutes the other surface layer of the multilayer film of the present invention, other than the seal layer (A). Furthermore, when the multilayer film is laminated with another substrate to form a laminate, the laminate layer is a layer that is bonded to the other substrate.

[0067] Examples of the polyolefin resin that is the main component of the laminate layer include the ethylene resin and propylene resin described above. From the viewpoint of preventing peeling between the base film and the layer, the polyolefin resin has a density of 0.880 to 0.960 g / cm. ３ The following ethylene-based resins and propylene-α-olefin random copolymers polymerized using a single-site catalyst are preferred, with ethylene-based resins being particularly preferred, and linear low-density polyethylene being more preferred.

[0068] As mentioned above, the density of the ethylene resin is 0.880 to 0.960 g / cm ３ is preferably 0.890 to 0.940 g / cm ３ More preferably, it is 0.890 to 0.935 g / cm ３ It is more preferable that the density is within this range. If the density is within this range, the resin has appropriate rigidity, excellent mechanical strength such as pinhole resistance, and improved film-forming properties and extrusion suitability. Furthermore, the melting point is generally preferably in the range of 60 to 140°C, more preferably 70 to 135°C, and even more preferably 90 to 130°C. If the melting point is within this range, processing stability (dead-hold properties) and co-extrusion processability are improved. Furthermore, the MFR (190°C, 21.18N) of the ethylene-based resin is preferably 0.5 to 50 g / 10 min, more preferably 1 to 30 g / 10 min, even more preferably 2 to 20 g / 10 min, and particularly preferably 5 to 15 g / 10 min. An MFR within this range is preferable in that good film-forming properties can be obtained. By using such an ethylene-based resin, transparency can be maintained when laminated. Furthermore, since the resin has flexibility, pinhole resistance is also improved.

[0069] The propylene-based resin in the laminate layer preferably has an MFR (230° C.) of 0.5 to 30.0 g / 10 min and a melting point of 110 to 165° C., and more preferably has an MFR (230° C.) of 2.0 to 15.0 g / 10 min and a melting point of 115 to 162° C. If the MFR and melting point are within these ranges, the film formability is improved.

[0070] The density of the propylene-based resin is not particularly limited and can be appropriately selected depending on the purpose. ３ ~0.93 g / cm ３ is preferred, and 0.90 g / cm ３ ~0.92 g / cm ３ is more preferred.

[0071] The melting point of the propylene-based resin is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 110°C to 170°C, more preferably 121°C to 166°C, and even more preferably 121°C to 140°C.

[0072] As described above, the laminate layer is primarily composed of a polyolefin resin, but resins other than polyolefin resins may be used in combination with the layer for the purpose of improving adhesion to adhesives or printing inks when laminating the layer with another substrate using an adhesive or when printing, etc. Examples of resins other than polyolefin resins that can be used in combination include ethylene copolymers such as ethylene-vinyl acetate copolymer (EVA), ethylene-methyl methacrylate copolymer (EMMA), ethylene-ethyl acrylate copolymer (EEA), ethylene-methyl acrylate (EMA) copolymer, ethylene-ethyl acrylate-maleic anhydride copolymer (E-EA-MAH), ethylene-acrylic acid copolymer (EAA), and ethylene-methacrylic acid copolymer (EMAA); as well as ionomers of ethylene-acrylic acid copolymers, ionomers of ethylene-methacrylic acid copolymers, and copolymers of ethylene and other monomers having a cyclic olefin structure, such as norbornene-based monomers. These resins may be used alone or in combination of two or more.

[0073] The laminate layer may contain components such as antifogging agents, antistatic agents, heat stabilizers, nucleating agents, antioxidants, lubricants, antiblocking agents, release agents, UV absorbers, colorants, and biodegradable agents, provided that the object of the present invention is not impaired. In particular, to ensure processability during film formation and packaging suitability for filling machines, the coefficient of friction of the multilayer film surface is preferably 2.0 or less, and more preferably 1.5 or less. Therefore, it is preferable to appropriately add lubricants, antiblocking agents, and antistatic agents to the laminate layer, which corresponds to the surface layer of the multilayer film. Additives such as lubricants and antiblocking agents are not particularly limited, and commercially available ones can be used. Furthermore, the antifogging agents described in detail for the sealing layer (A) can be used.

[0074] (Intermediate Layer) The multilayer film of the present invention may include an intermediate layer. The intermediate layer is a layer mainly composed of a polyolefin resin, and as described above, is located between the laminate layer and the resin layer (B) used in the present invention. Examples of the polyolefin resin mainly composed of the intermediate layer include polyolefin resins similar to the polyolefin resin mainly composed of the laminate layer, and the same applies to preferred polyolefin resins. The polyolefin resin used in the intermediate layer and the polyolefin resin used in the laminate layer may be the same or different polyolefin resins, but it is preferable to use a combination of polyolefin resins of the same type in order to prevent peeling between the layers. When combining polyolefin resins of the same type, the densities may be the same or different.

[0075] The proportion of the polyolefin resin in the intermediate layer is preferably 50% by mass or more, more preferably 70% by mass or more, and particularly preferably 90% by mass or more. Other resins that can be used in combination are the same as those exemplified as resins that can be used in combination in the laminate layer.

[0076] The multilayer film of the present invention may not have any intermediate layer, may be a single layer, or may have two or more layers.

[0077] The intermediate layer may also contain components such as antistatic agents, heat stabilizers, nucleating agents, antioxidants, lubricants, antiblocking agents, release agents, UV absorbers, colorants, and biodegradable agents, provided that the objects of the present invention are not impaired. The intermediate layer may also contain an antifogging agent. When the intermediate layer contains an antifogging agent, the antifogging agent may migrate between layers, resulting in a decrease in seal strength. However, such a problem is unlikely to occur in the multilayer film of the present invention.

[0078] <Multilayer Film> The multilayer film of the present invention is a multilayer film including a seal layer (A) and a resin layer (B) adjacent to the seal layer (A). Examples of layer configurations include: (1) (laminate layer) / (intermediate layer) / (resin layer (B)) / (seal layer (A)); (2) (laminate layer) / (resin layer (B)) / (seal layer (A)); and (3) (laminate layer) / (intermediate layer) / (intermediate layer) / (resin layer (B)) / (seal layer (A)). These are examples of specific embodiments of the present invention, and the present invention is not limited to these. Among these, the configuration of (1), in which the (laminate layer) / (intermediate layer) / (resin layer (B)) / (seal layer (A)) is stacked, is preferred.

[0079] The multilayer film of the present invention can realize excellent anti-fogging properties, can achieve suitable seal strength when heat-sealed, and can maintain suitable easy-open properties between the seal layer (A) and the resin layer (B) used in the present invention when opened. Furthermore, the anti-fogging agent is less likely to fall off, the anti-fogging properties can be stably maintained, and the film also has good adhesion to printing and other substrates.

[0080] The total thickness of the multilayer film of the present invention is preferably 20 μm or more because this facilitates film formation, and is preferably 100 μm or less, particularly preferably 50 μm or less, because this facilitates lamination when the multilayer film of the present invention is used in combination with another substrate.

[0081] In addition, from the viewpoints of sealability, easy-openability, and lamination, it is preferable that the thickness ratio of each layer in the multilayer film is such that the thickness ratio of the laminate layer is in the range of 20 to 85%, the thickness ratio of the resin layer (B) is in the range of 10 to 40%, and the thickness ratio of the seal layer (A) is in the range of 5 to 20%.

[0082] The total amount of antifogging agent contained in the entire antifogging multilayer film of the present invention is preferably 0.1 mass% or more relative to the total mass of the film. When the total amount of antifogging agent is within this range, favorable antifogging properties and durability of antifogging properties can be obtained. Furthermore, the upper limit of the total amount of antifogging agent is preferably 0.7 mass% or less, and particularly preferably 0.5 mass% or less, relative to the total mass of the film. When the total amount of antifogging agent is within this range, film tearability is improved and deterioration of seal strength over time is easily suppressed.

[0083] In the multilayer film of the present invention, the surface of the laminate layer is preferably treated to a wetting tension in the range of 35 to 45 mN / m. Examples of such treatment methods include surface oxidation treatments such as corona discharge treatment, plasma treatment, chromic acid treatment, flame treatment, hot air treatment, and ozone / ultraviolet treatment, as well as surface roughening treatments such as sandblasting, with corona discharge treatment being preferred. Such surface treatments improve the coatability of inks and adhesives when subsequent processes, such as printing or applying an adhesive to the surface of the polyolefin resin layer of the multilayer film and laminating it to a substrate, and provide excellent adhesion to inks, aluminum, anchor coating agents, and the like, thereby making it easier to avoid problems such as ink or vapor-deposited aluminum peeling and delamination.

[0084] In the multilayer film of the present invention, it is also preferable that the surface on the sealing layer (A) side is treated to have a wet tension in the range of 50 to 60 mN / m. By treating the surface on the sealing layer (A) side, it becomes possible to fix the antifogging agent to the surface for a relatively long period of time, resulting in a film with excellent antifogging properties and antifogging durability. The treatment method and treatment degree for the surface on the polyolefin resin layer side and the surface on the sealing layer (A) side may be the same or different, but from the viewpoint of productivity, it is preferable to treat them by the same method.

[0085] (Production Method) The method for producing the multilayer film of the present invention is not particularly limited, but examples include a coextrusion method in which each resin or resin mixture used for each layer is heated and melted in a separate extruder, laminated in the molten state in the order required for the layer structure of the present invention using a method such as a coextrusion multilayer die method or a feed block method, and then formed into a film using an inflation method or a T-die / chill roll method. This coextrusion method is preferred because it allows relatively free adjustment of the thickness ratio of each layer and produces a multilayer film that is hygienic and cost-effective. Among these, the T-die / chill roll method is preferred because it prevents deterioration of the film appearance when coextruding resins with different melting points or Tg's, facilitates the formation of a uniform layer structure, and facilitates the production of a multilayer film with suitable transparency and gloss. The inflation method is also preferred because it requires simple equipment and is suitable for small-lot, high-mix production.

[0086] The multilayer film of the present invention can be obtained as a substantially unstretched multilayer film by the above-mentioned production method, and therefore can be subjected to secondary forming such as deep drawing by vacuum forming and embossing.

[0087] Immediately after extrusion of the laminate layer or the seal layer, the laminate layer or the seal layer may be embossed by contacting it with a roll having irregularities.

[0088] (Laminate) The multilayer film of the present invention can be laminated to a substrate, for example, by bonding it to form a laminate. Examples of the configuration of the laminate of the present invention include, but are not limited to, (1) substrate / adhesive layer / multilayer film of the present invention (2) substrate / adhesive layer / printed layer / multilayer film of the present invention (3) substrate / adhesive layer / second substrate / printed layer / adhesive layer / multilayer film of the present invention (4) substrate / adhesive layer / first printed layer / second printed layer / multilayer film of the present invention (5) substrate / adhesive layer / barrier layer / adhesive layer / multilayer film of the present invention (6) substrate / adhesive layer / barrier layer / printed layer / adhesive layer / multilayer film of the present invention (7) substrate / printed layer / adhesive layer / multilayer film of the present invention (8) substrate / first printed layer / second printed layer / adhesive layer / multilayer film of the present invention (9) substrate / printed layer / adhesive layer / barrier layer / adhesive layer / multilayer film of the present invention, and the laminate may further include an additional substrate. The second and additional substrates may be unstretched resin films, stretched resin films, metal-deposited films such as metal-deposited unstretched films and metal-deposited stretched films, transparent vapor-deposited films, or papers such as coated paper and fine paper, and are not particularly limited. Furthermore, the multiple adhesive layers may have the same composition or different compositions. Furthermore, an anchor coat layer may be sandwiched between the adhesive layers to improve the adhesive strength.

[0089] The method for laminating the multilayer film of the present invention and the substrate film is not particularly limited, and any of a number of composite techniques such as dry lamination, wet lamination, non-solvent lamination, extrusion lamination, sand lamination, and thermal lamination may be used.

[0090] Examples of the stretched resin film include biaxially oriented polyester (PET), easily tearable biaxially oriented polyester (PET), biaxially oriented polypropylene (OPP), biaxially oriented polyamide (PA), coextruded biaxially oriented polypropylene with a central layer of ethylene-vinyl alcohol copolymer (EVOH), biaxially oriented ethylene-vinyl alcohol copolymer (EVOH), and coextruded biaxially oriented polypropylene coated with polyvinylidene chloride (PVDC). Among these, films made of α-olefin resins are preferred, and polypropylene-based resin films such as biaxially oriented polypropylene (OPP) are particularly preferred. Furthermore, plastic films may be coated to improve gas barrier properties or ink receptivity when forming a printing layer, as described below. Commercially available coated plastic films include K-OPP film and K-PET film. These may be used alone or in combination.

[0091] The thickness of the stretched resin film is preferably 10 to 60 μm, more preferably 20 to 40 μm, and even more preferably 20 to 30 μm. When the thickness of the stretched resin film is in this range, production of a laminate film becomes easy.

[0092] Examples of the unstretched resin film include a CPP film, a nylon film, a PET film, a PVC film, etc. A combination of two or more substrates can also be used.

[0093] The substrate may also be formed from a biomass polyolefin. The biomass polyolefin refers to a polyolefin resin using a plant-derived olefin as a raw material monomer. The raw material monomer may contain a petroleum-derived monomer, and may not contain 100% plant-derived monomers. Commercially available biomass polyolefins may also be used. Examples of commercially available products include SGM9450F, SLL118, SLL118 / 21, SLL218, SLL318, SLH118, SLH218, and SLH0820 manufactured by Braskem.

[0094] The substrate to be laminated on the multilayer film of the present invention may be a substrate having a vapor-deposited layer made of an inorganic substance and / or inorganic oxide provided on the above-mentioned resin film. By using a substrate having such a vapor-deposited layer, barrier properties can be imparted to the laminate of the present invention. The vapor-deposited layer can be formed by a known method using a known inorganic substance or inorganic oxide, and its composition and formation method are not particularly limited. Furthermore, a laminate film made of the multilayer film of the present invention may have two or more vapor-deposited layers, which may have the same composition or different compositions.

[0095] The vapor-deposited layer may be, for example, a vapor-deposited film of an inorganic substance or inorganic oxide such as silicon (Si), aluminum (Al), magnesium (Mg), calcium (Ca), potassium (K), tin (Sn), sodium (Na), boron (B), titanium (Ti), lead (Pb), zirconium (Zr), yttrium (Y), etc. Vapor-deposited films of inorganic oxides such as silicon oxide and aluminum oxide are transparent.

[0096] The inorganic oxides are expressed as MOx (where M represents an inorganic element), such as SiOx and AlOx. The value of x can range from 0 to 2 for silicon (Si), 0 to 1.5 for aluminum (Al), 0 to 1.5 for magnesium (Mg), 0 to 1 for calcium (Ca), 0 to 0.5 for potassium (K), 0 to 2 for tin (Sn), 0 to 0.5 for sodium (Na), 0 to 1.5 for boron (B), 0 to 1.5 for titanium (Ti), 0 to 2 for lead (Pb), 0 to 1 for zirconium (Zr), and 0 to 1.5 for yttrium (Y). In the above, when x = 0, the material is a completely inorganic element (pure substance) and is not transparent. When the value of x is at the upper limit of the range, the material is completely oxidized. Silicon (Si) or aluminum (Al) is preferably used as the vapor deposition layer, and silicon (Si) having an x ​​value in the range of 1.0 to 2.0 and aluminum (Al) having an x ​​value in the range of 0.5 to 1.5 can be used.

[0097] The vapor deposition layer can be formed on the surface of the substrate or the like by a physical vapor deposition method (PVD method) such as vacuum deposition, sputtering, or ion plating, or a chemical vapor deposition method (CVD method) such as plasma chemical vapor deposition, thermal chemical vapor deposition, or photochemical vapor deposition.

[0098] The thickness of the vapor-deposited layer is not particularly limited as long as the vapor-deposited layer alone can exhibit a certain level of gas barrier function. The preferred thickness range varies depending on the type of metal or metal oxide to be vapor-deposited, but is preferably 0.05 to 70 nm, more preferably 0.1 to 70 nm, still more preferably 3 to 70 nm, and even more preferably 5 to 60 nm.

[0099] Examples of the metal-deposited film include a VM-CPP film obtained by depositing a metal such as aluminum on a CPP film, and a VM-OPP film obtained by depositing a metal such as aluminum on an OPP film. Examples of the transparent deposited film include films obtained by depositing silica or alumina on an OPP film, PET film, nylon film, or the like. For the purpose of protecting the inorganic deposited layer of silica or alumina, a film with a coating applied to the deposited layer may also be used.

[0100] In addition, for applications that do not require transparency, aluminum foil can be used alone or in combination as a barrier layer, but since the multilayer film of the present invention has excellent anti-fogging properties, it is preferable not to use aluminum foil as a barrier layer in order to exhibit the anti-fogging properties.

[0101] Paper can also be used as the substrate. Examples of the substrate that can be used include paperboard such as coated cardboard, cardboard, ivory paper, and manila cardboard used for printing on packaging materials and the like for cosmetics, beverages, pharmaceuticals, toys, and equipment, as well as paper such as milk carton base paper, cup base paper, fine paper, kraft paper, pure white roll paper, glassine paper, parchment paper, manila cardboard, white cardboard, coated paper, art paper, imitation paper, thin paper, thick paper, and polyethylene-coated paper, as well as various synthetic papers and acid-resistant papers.

[0102] Examples of the lamination method for laminating the above-mentioned substrate or a substrate that has been printed or vapor-deposited onto the multilayer film of the present invention to form a laminate include dry lamination, wet lamination, non-solvent lamination, extrusion lamination, etc. In this case, the layer located between the sealant film and the substrate is called an adhesive layer.

[0103] Examples of adhesives used in the dry lamination include solvent-based two-component curing adhesives, etc. A "solvent-based" adhesive refers to a form used in a so-called dry lamination method, in which the adhesive is applied to a substrate, heated in an oven or the like to volatilize the organic solvent in the coating, and then bonded to another substrate, and includes a polyisocyanate composition, a polyol composition, and an organic solvent capable of dissolving (diluting) them.

[0104] In the two-component curing adhesive, in consideration of the creation of a sustainable recycling-based society (sustainability), it is preferable to use plant-derived materials (biomass materials) as raw materials for the polyisocyanate composition or polyol composition. By appropriately using biomass materials, the environmental impact can be reduced. Examples of biomass materials include castor oil-based polyols such as castor oil, dehydrated castor oil, hydrogenated castor oil (a hydrogenated castor oil), and 5 to 50 mol alkylene oxide adducts of castor oil; aliphatic polybasic acids such as succinic acid, succinic anhydride, glutaric acid, adipic acid, azelaic acid, sebacic acid, and itaconic acid; alkyl esters of these acids; and dimer acids.

[0105] Commercially available adhesives using biomass raw materials can also be used, such as those listed by the Japan Organics Resources Association, including DIC Dry BM (manufactured by DIC Corporation) and Takenate BM (manufactured by Mitsui Chemicals, Inc.).

[0106] The weight of the adhesive layer after drying is 0.1 to 10 g / m ２ It is preferable that the density is 1 to 6 g / m ２ More preferably, it is 2 to 5 g / m ２ The thickness of the adhesive layer is preferably 0.1 to 10 μm, more preferably 1 to 7 μm, and even more preferably 2 to 5 μm.

[0107] Although various pressure-sensitive adhesives can be used for the adhesive layer, it is preferable to use a pressure-sensitive adhesive. Examples of such pressure-sensitive adhesives include rubber-based adhesives obtained by dissolving polyisobutylene rubber, butyl rubber, or mixtures thereof in organic solvents such as benzene, toluene, xylene, and hexane, or those rubber-based adhesives blended with tackifiers such as abiethylene acid rosin ester, terpene-phenol copolymer, and terpene-indene copolymer, and acrylic-based adhesives obtained by dissolving an acrylic copolymer having a glass transition temperature of −20° C. or lower, such as a 2-ethylhexyl acrylate-n-butyl acrylate copolymer or a 2-ethylhexyl acrylate-ethyl acrylate-methyl methacrylate copolymer, in an organic solvent.

[0108] When a material having gas barrier properties is used as the adhesive or the anchor coating agent described below, a laminate film having particularly excellent gas barrier properties can be obtained. ２ The oxygen barrier property of the cured coating film of the adhesive applied at (solid content) is 300 cc / m ２ / day / atm or less, or water vapor barrier property of 120 g / m ２ Commercially available products include the "PASLIM" series, such as PASLIM VM001 and PASLIM J350X manufactured by DIC Corporation, and "MAXIEVE" manufactured by Mitsubishi Gas Chemical Company, Inc.

[0109] The adhesive layer can also be formed from a thermoplastic resin, and the method for forming the adhesive layer can be a conventionally known method, such as a melt extrusion lamination method or a sand lamination method. Examples of the thermoplastic resin that can be used for the adhesive layer include polyethylene resins such as low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), medium-density polyethylene (MDPE), and high-density polyethylene (HDPE), polypropylene resins such as propylene homopolymers, propylene-α-olefin random copolymers, and propylene-α-olefin block copolymers, norbornene polymers and hydrogenated products thereof, such as norbornene copolymers (COC) obtained by copolymerizing norbornene monomers with olefins such as ethylene, vinyl alicyclic hydrocarbon polymers, and cyclic conjugated diene polymers, and cyclic polyolefin resins such as ethylene homopolymers, propylene copolymers (COC), and propylene copolymers (COC) obtained by copolymerizing norbornene monomers with olefins such as ethylene. Examples of suitable elastomers include polyethylene-based elastomers such as ethylene-vinyl acetate copolymer (EVA) and ethylene-α-olefin copolymers, polypropylene-based elastomers, and butene-based elastomers; ethylene-based copolymers such as ethylene-methyl methacrylate copolymer (EMMA), ethylene-ethyl acrylate copolymer (EEA), ethylene-methyl acrylate (EMA) copolymer, ethylene-ethyl acrylate-maleic anhydride copolymer (E-EA-MAH), ethylene-acrylic acid copolymer (EAA), and ethylene-methacrylic acid copolymer (EMAA); and ionomers of ethylene-acrylic acid copolymers and ionomers of ethylene-methacrylic acid copolymers. Furthermore, in order to improve interlayer adhesion, acid-modified polyolefin-based resins obtained by modifying the above-mentioned polyolefin-based resins with unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, and itaconic acid can also be used. In addition, resins obtained by graft polymerizing or copolymerizing unsaturated carboxylic acids, unsaturated carboxylic anhydrides, or ester monomers with polyolefin resins can also be used. These resins can be used alone or in combination of two or more. It is also preferable to use polyethylene-based resins that use biomass-derived ethylene as a monomer unit.

[0110] When laminating an adhesive layer using extrusion lamination, an anchor coating layer may be formed by applying and drying an anchor coating agent to the surface of the layer to be laminated. Examples of anchor coating agents include anchor coating agents made of any resin with a heat resistance temperature of 135°C or higher, such as polybutadiene-based resins, urethane resins, polyisocyanate-polyether polyols, polyethyleneimine, vinyl-modified resins, epoxy resins, polyester resins, and alkyl titanates, as well as anchor coating agents obtained by diluting the above adhesives with organic solvents. Among these, polyethyleneimine-based anchor coating agents and anchor coating agents obtained by diluting the above adhesives with organic solvents are preferred. A silane coupling agent may also be used as an additive, and soluble nitrocellulose may also be used to enhance heat resistance.

[0111] When the laminate of the present invention is obtained by laminating the multilayer film of the present invention and a substrate or the like by extrusion lamination or sand lamination, the nip roll or chill roll used during lamination may be replaced with an embossing roll to apply embossing to the surface of the seal layer side.

[0112] The laminate of the present invention may further include a printed layer between the multilayer film of the present invention and the substrate. The printed layer is a layer on which a desired design is formed using liquid printing ink to impart aesthetic appeal, various content-related information, and functionality to the printed object. The printed layer is formed by printing a gravure printing ink or flexographic printing ink (hereinafter referred to as liquid printing ink) containing a binder resin and a colorant, an active energy ray-curable ink, or an inkjet ink. The printed layer may be a single layer or may include multiple printed layers. When multiple printed layers are present, the liquid printing inks used for each printed layer may be the same, or may have the same composition but with different colorants, or may have different compositions. Furthermore, printing may involve the use of two types of printing inks in combination, such as a liquid printing ink and an inkjet ink. When there are multiple printed layers, the printed matter may have, for example, a first printed layer formed from a printing ink containing a colorant, a second white printed layer formed from a liquid ink containing a white pigment as a colorant, and a third white printed layer, in that order. The first printed layer can form a pattern using a colorant, and the second white printed layer and the third printed layer, both formed from liquid ink containing a white pigment, can be used as a background for the pattern. If the second or third printed layer is an overprint varnish, it does not need to contain a colorant.

[0113] The liquid printing inks are used as gravure printing inks or flexographic printing inks, and are broadly classified into organic solvent-based liquid printing inks, which use organic solvents as the main solvent, and water-based liquid printing inks, which use water as the main solvent. The printing layer is preferably a general-purpose organic solvent-based liquid printing ink.

[0114] The organic solvent-based liquid printing ink is prepared by dispersing a mixture of pigment, binder resin, organic solvent medium, dispersant, antifoaming agent, etc. in a disperser to obtain a pigment dispersion. The resulting pigment dispersion is then mixed with a resin, an aqueous medium, and, if necessary, additives such as a leveling agent, followed by stirring and mixing. The ink is prepared using a disperser such as a bead mill, Eiger mill, sand mill, gamma mill, or attritor, which is commonly used in the production of gravure and flexographic printing inks.

[0115] Examples of the binder resin include cellulose-based resins such as nitrocellulose, cellulose acetate propionate (CAP) and cellulose acetate butyronate (CAB), polyamide-based resins, polyurethane resins, acrylic resins, vinyl chloride-based resins such as vinyl chloride-vinyl acetate copolymer resins, chlorinated polypropylene resins, ethylene-vinyl acetate copolymer resins, vinyl acetate resins, polyvinyl chloride resins and vinyl chloride-acrylic copolymer resins, polyester resins, alkyd resins, rosin-based resins, rosin-modified maleic acid resins, ketone resins, cyclized rubber, chlorinated rubber, butyral, petroleum resins, etc. Among these, polyurethane resins are preferably used.

[0116] The polyurethane resin is preferably a polyurethane resin obtained by polymerizing a polyol and a polyisocyanate. The polyol is preferably a polyester polyol. If necessary, the polyurethane resin may be synthesized by using a general-purpose polyol other than polyether polyol, polyester polyol, or polyether polyol, a chain extender, or a terminal blocking agent. Furthermore, the polyol may be reacted with a polyisocyanate to form a urethane prepolymer having an isocyanate group at its terminal, and the resulting urethane prepolymer may be reacted with a polyamine compound to synthesize the polyurethane resin. The polyurethane resin may be used alone or in combination in the liquid ink.

[0117] Examples of the pigment include inorganic pigments and organic pigments used in general inks, paints, recording agents, etc. Examples of the organic pigment include soluble azo pigments, insoluble azo pigments, azo pigments, phthalocyanine pigments, halogenated phthalocyanine pigments, anthraquinone pigments, anthanthrone pigments, dianthraquinonyl pigments, anthrapyrimidine pigments, perylene pigments, perinone pigments, quinacridone pigments, thioindigo pigments, dioxazine pigments, isoindolinone pigments, quinophthalone pigments, azomethine azo pigments, flavanthrone pigments, diketopyrrolopyrrole pigments, isoindoline pigments, indanthrone pigments, and carbon black pigments. Other examples include carmine 6B, lake red C, permanent red 2B, disazo yellow, pyrazolone orange, carmine FB, cromophtal yellow, cromophtal red, phthalocyanine blue, phthalocyanine green, dioxazine violet, quinacridone magenta, quinacridone red, indanthrone blue, pyrimidine yellow, thioindigo bordeaux, thioindigo magenta, perylene red, perinone orange, isoindolinone yellow, aniline black, diketopyrrolopyrrole red, daylight fluorescent pigments, etc. In addition, both non-acid-treated pigments and acid-treated pigments can be used.

[0118] Examples of the inorganic pigment include white inorganic pigments such as titanium oxide, zinc oxide, zinc sulfide, barium sulfate, calcium carbonate, chromium oxide, silica, lithopone, antimony white, and gypsum. Among the inorganic pigments, titanium oxide is particularly preferred. Titanium oxide exhibits a white color and is preferred in terms of coloring power, hiding power, chemical resistance, and weather resistance. From the viewpoint of printing performance, titanium oxide is preferably treated with silica and / or alumina. Examples of inorganic pigments other than white include aluminum particles, mica, bronze powder, chrome vermilion, yellow lead, cadmium yellow, cadmium red, ultramarine, Prussian blue, red iron oxide, yellow iron oxide, iron black, and zircon. Aluminum is in powder or paste form, but is preferably used in paste form from the viewpoints of handleability and safety. Whether to use leafing or non-leafing is appropriately selected from the viewpoints of brightness and density.

[0119] The organic solvent is not particularly limited, and examples thereof include aromatic hydrocarbon organic solvents such as toluene, xylene, Solvesso #100, and Solvesso #150; aliphatic hydrocarbon organic solvents such as hexane, methylcyclohexane, heptane, octane, and decane; and various ester organic solvents such as methyl acetate, ethyl acetate, isopropyl acetate, normal propyl acetate, butyl acetate, amyl acetate, ethyl formate, and butyl propionate. Examples of water-miscible organic solvents include alcohols such as methanol, ethanol, propanol, butanol, and isopropyl alcohol, ketones such as acetone, methyl ethyl ketone, and cyclohexanone, and glycol ethers such as ethylene glycol (mono, di)methyl ether, ethylene glycol (mono, di)ethyl ether, ethylene glycol monopropyl ether, ethylene glycol monoisopropyl ether, monobutyl ether, diethylene glycol (mono, di)methyl ether, diethylene glycol (mono, di)ethyl ether, diethylene glycol monoisopropyl ether, diethylene glycol monobutyl ether, triethylene glycol (mono, di)methyl ether, propylene glycol (mono, di)methyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, and dipropylene glycol (mono, di)methyl ether. These can be used alone or in combination of two or more.

[0120] From the viewpoints of work hygiene during printing and the harmfulness of packaging materials, it is more preferable to use ethyl acetate, propyl acetate, isopropanol, normal propanol, etc., and not use aromatic solvents such as toluene or ketone solvents such as methyl ethyl ketone. Among these, from the viewpoint of the solubility of polyurethane resin, a mixture of isopropyl alcohol / ethyl acetate / methoxypropanol is more preferable. Furthermore, glycol ethers can be added in an amount of less than 10% by mass of the total ink to adjust the drying property.

[0121] The organic solvent-based liquid printing ink has excellent adhesion to various substrates and can be used for printing on paper, synthetic paper, thermoplastic resin films, plastic products, steel plates, etc., and is useful as an ink for gravure printing using a gravure printing plate made by electronic intaglio or the like, or for flexographic printing using a flexographic printing plate made by a resin plate or the like. The film thickness of the liquid printing ink formed by gravure printing or flexographic printing using the organic solvent-based liquid printing ink is preferably 0.1 to 10 μm, more preferably 1 to 5 μm, and even more preferably 1 to 3 μm. The weight of the printed layer after drying is 0.1 to 10 g / m ２ It is preferable that the density is 1 to 5 g / m ２ More preferably, it is 1 to 3 g / m ２ It is more preferable that:

[0122] In view of the establishment of a recycling-based society that should develop sustainably (sustainability), it is preferable to use a liquid printing ink that uses plant-derived raw materials (biomass raw materials). Examples of plant-derived raw materials include cellulose resins such as cellulose acetate propionate resin and nitrocellulose; polyamide resins using dimer acids or polymerized fatty acids derived from natural oils such as soybean oil, palm oil, and rice bran oil; polycarboxylic acids such as succinic acid, succinic anhydride, adipic acid, azelaic acid, sebacic acid, dimer acid, glutaric acid, and malic acid; polyols such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, pentylene glycol, 1,10-dodecanediol, dimer diol, and isosorbide; and polyisocyanates such as 1,5-pentamethylene diisocyanate and dimer diisocyanate. Examples of plant-derived raw materials include biomass polyurethanes, rosin resins, dammar resins, and polylactic acid.

[0123] The liquid printing ink using the plant-derived raw materials may be commercially available, such as inks listed in the Japan Organics Recycling Association, including Finart BM (manufactured by DIC Corporation), LP Bio Series (manufactured by Toyo Ink Co., Ltd.), Bellflora (manufactured by Sakata Inx Corporation), and NB300 BP Series (manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd.).

[0124] The printing layer may be printed on another substrate by so-called reverse printing, and then the substrate and the multilayer film of the present invention may be laminated by methods such as dry lamination, sand lamination, or extrusion lamination. Extrusion lamination is preferred because it reduces the production load, since it is possible to produce the multilayer film of the present invention, laminate it on the substrate, and optionally emboss the seal layer of the multilayer film in a single process. An anchor coat varnish, an overcoat varnish, or the like may also be used.

[0125] <Packaging Material> The use of the multilayer film or laminate of the present invention is not particularly limited, but it can be used as a packaging material for foods, medicines, industrial parts, miscellaneous goods, magazines, etc., and can be particularly suitably used as a lid material for packaging containers. In particular, it is preferable that the outermost layer of the packaging container (the portion that adheres to the seal layer (A) of the multilayer film of the present invention) contains a polyester-based resin from the viewpoint of a balance between easy opening and seal strength. Furthermore, since it exhibits excellent anti-fogging properties, it can be suitably used for packaging foods that contain a lot of moisture, and is preferably used as a lid material for food packaging containers.

[0126] The packaging bag is preferably one formed by overlapping and sealing the sealing layers of the multilayer film or laminate of the present invention, or by overlapping and sealing the outermost layer and the sealing layer. For example, two sheets of the multilayer film are cut to the desired size of the packaging bag, overlapped, and sealed on three sides to form a bag, and then the contents are filled in through the unsealed side and sealed. Furthermore, a packaging bag can be formed by sealing the ends of a rolled film into a cylindrical shape using an automatic packaging machine, and then sealing the top and bottom.

[0127] The multilayer film or laminate of the present invention can also be used to form a packaging bag or container by overlaying and sealing another sealable film on the seal layer (A). In this case, a film with relatively low mechanical strength, such as LDPE or EVA, can be used as the other film. A laminate film formed by bonding a film such as LDPE or EVA with a stretched film with relatively good tearability, such as a biaxially oriented polyethylene terephthalate film (OPET) or a biaxially oriented polypropylene film (OPP), can also be used.

[0128] (Sealing Method) The multilayer film or laminate of the present invention has sealability and can be sealed to form a package. The seal strength of the multilayer film or laminate of the present invention can be adjusted appropriately depending on the mode of use. For example, the multilayer film or laminate of the present invention is heat-sealed to an A-PET sheet (softening point 77°C, crystallization temperature 126°C) at a temperature of 140°C and a pressure of 0.2 MPa for 1.0 second, and then a 15 mm wide test piece is cut out. The maximum load when peeled in a 180° direction at a tensile rate of 300 mm / min in a thermostatic chamber at 23°C and 50% RH is preferably 3 N / 15 mm or more, more preferably 5 N / 15 mm or more, and even more preferably 6 N / 15 mm or more. The upper limit of the maximum load is preferably less than 20 N / 15 mm, more preferably less than 15 N / 15 mm. By achieving this peel strength, the multilayer film is less likely to peel or fall off, and is particularly easy to open. In addition to heat sealing, the multilayer film of the present invention can also be sealed by ultrasonic waves. There are no particular limitations on the method of ultrasonic sealing, and any known ultrasonic sealing method or method using a known ultrasonic sealing device can be appropriately selected depending on the purpose.

[0129] In packaging materials using the multilayer film or laminate of the present invention, it is preferable to form any tear initiation portion such as a V notch, I notch, perforation, or micropore in the sealed portion in order to weaken the initial tear strength and improve openability.

[0130] The present invention will now be described in more detail with reference to examples and comparative examples. Unless otherwise specified, "parts" are by mass.

[0131] <Polyester Resin> The compositions of the polyester resins used are shown below. Polyester 1: terephthalic acid / isophthalic acid / ethylene glycol = 30 / 10 / 40 (molar ratio) [glass transition temperature: 72°C] Polyester 2: terephthalic acid / ethylene glycol / 1,4-cyclohexanedimethanol / isosorbide = 50 / 20 / 27.5 / 2.5 (molar ratio) [glass transition temperature: 90°C] Polyester 3: terephthalic acid / adipic acid / 1,4-butanediol = 24.5 / 25.5 / 50 (molar ratio) [glass transition temperature: -35°C, melting point: 120°C] Polyester 4: terephthalic acid / isophthalic acid / polytetramethylene ether glycol / 1,4 butanediol = 33.3 / 16.7 / 33.3 / 16.7 [glass transition temperature: -70°C, melting point: 127°C] Polyester 5: Terephthalic acid / 1,4 butanediol / polytetramethylene ether glycol=50 / 35 / 15 (glass transition temperature: −32°C, melting point: 165°C)

[0132] <Preparation of Anti-Fog Agent Masterbatch Based on Polyester Resin> (Preparation Example 1) [Preparation of Anti-Fog Agent Masterbatch Based on Polyester 1] 90 parts of Polyester 1 and 10 parts of a nonionic surfactant (diglycerin fatty acid ester, HLB: 6) were melt-kneaded and granulated to obtain anti-fogging agent masterbatch pellets (hereinafter referred to as anti-fogging agent MB1).

[0133] (Preparation Example 2) [Preparation of anti-fog agent master batch based on polyester 2] 90 parts of polyester 2 and 10 parts of a nonionic surfactant (diglycerol fatty acid ester, HLB: 6) were melt-kneaded and granulated to obtain anti-fog agent master batch pellets (hereinafter referred to as anti-fog agent MB2).

[0134] (Preparation Example 3) [Preparation of anti-fog agent master batch based on Polyester 5] 90 parts of Polyester 5 and 10 parts of a nonionic surfactant (diglycerin fatty acid ester, HLB: 6) were melt-kneaded and granulated to obtain anti-fog agent master batch pellets (hereinafter referred to as anti-fog agent MB3).

[0135] (Example 1) A mixture of polyester 1, polyester 3, and anti-fogging agent MB1 was used as the sealing layer (A) in a ratio of polyester 1 / polyester 3 / nonionic surfactant = 48 parts / 48.5 parts / 3.5 parts, and a linear low-density polyethylene (density 0.93 g / cm) was used as the laminating layer. ３ , melt flow rate 6 g / 10 min (230 ° C.; hereinafter referred to as LLDPE)] was used, LLDPE was used as the intermediate layer, and an acid-modified ethylene-propylene-butene copolymer (acid modification amount 2.9 parts by mass, density 0.89 g / cm) was used as the resin layer (B). ３ The resins were supplied to an extruder for a sealing layer (A) (diameter 40 mm), an extruder for a resin layer (B) (diameter 40 mm), an extruder for an intermediate layer (diameter 50 mm), and an extruder for a laminate layer (diameter 50 mm), respectively, and extruded by a co-extrusion method from a T-die at an extrusion temperature of 230°C so that the thicknesses of the laminate layer / intermediate layer / resin layer (B) / sealing layer (A) would be 9 μm / 12 μm / 6 μm / 3 μm, respectively. The film was cooled with a water-cooled metal cooling roll at 30°C, subjected to a corona discharge treatment so that the wet tension of the laminate layer would be 40 mN / m, then taken up on a roll and aged for 36 hours in an aging chamber at 40°C, to obtain a multilayer film of Example 1 having a total thickness of 30 μm.

[0136] (Examples 2 to 8) Films of Examples 2 to 7 were produced in the same manner as in Example 1, except that the compositions shown in the table were used.

[0137] Example 9 A film of Example 9 was produced in the same manner as in Example 1, except that a mixture of an antiblocking agent (CAS number: 1344-01-0), Polyester 1, Polyester 3, and antifogging agent MB1 was used as the sealing layer (A), with a ratio of Polyester 1 / Polyester 3 / nonionic surfactant / antiblocking agent = 65.5 parts / 30 parts / 3.5 parts / 1 part, and a polyethylene-based antifogging agent MB (ESR-702 manufactured by Riken Vitamin Co., Ltd.) and silica (CAS number: 7631-86-9) was used as the antiblocking agent, with a ratio of LLDPE / antifogging agent / antiblocking agent = 98.5 parts / 0.5 parts / 1 part was used as the laminating layer.

[0138] Example 10 A film of Example 10 was produced in the same manner as in Example 1 except that the composition shown in the table was used.

[0139] Comparative Examples 1 to 7 Films of Comparative Examples 1 to 7 were produced in the same manner as in Example 1, except that the compositions shown in the table were used.

[0140] (Evaluation of anti-fogging properties) A ​​biaxially stretched polyester film with a thickness of 12 μm was laminated onto the polyolefin resin layer side of the obtained multilayer film using a dry lamination adhesive to prepare a laminate film. In this case, a two-component curing adhesive (polyester adhesive "LX500" and curing agent "KW-75") manufactured by DIC Corporation was used as the dry lamination adhesive. The film was made of A-PET, had a 5 mm wide, smooth surface, a square shape with a side length of 88 mm, and a capacity of 80 cm. ３ 30 ml of water at 40°C was poured into the container, and the seal layer (A) side of the obtained laminate film was placed on the container, heat-sealed using a cup sealer, and then stored at 3°C. After 1 hour and 3 hours, the anti-fogging effect was visually confirmed according to the following criteria. (Anti-fogging evaluation criteria) ⊚: A continuous water film was formed on the film surface at 1 hour, and visibility was good. ○: A continuous water film was formed on the film surface at 3 hours, and visibility was good. ×: Water droplets were attached, and visibility was deteriorated.

[0141] (Method for evaluating peel surface (film tearability) after cup sealing) For the A-PET containers for which the anti-fogging properties were measured above, a peel test was carried out using a 45° peel test jig (manufactured by Imada Co., Ltd.) with the peel angle fixed at 45°. The appearance of the container after peeling was visually inspected and evaluated according to the following criteria. (Criteria for evaluating film tearability) ⊚: No film residue occurs even when opened at 30 mm / min. ◯: No film residue occurs even when opened at 100 mm / min. △: No film residue occurs even when opened at 250 mm / min. ×: Film residue occurs in the seal layer (A).

[0142] (Evaluation of heat sealability) The seal layer (A) surface of the laminate film was placed on an A-PET sheet (softening point 77°C, crystallization temperature 126°C), and heat-sealed for 1.0 second using a precision heat sealer (manufactured by Tester Sangyo) at a temperature of 140°C and a pressure of 0.2 MPa with a 10 mm wide seal bar, and then allowed to cool. A 15 mm wide test piece was then cut from the heat-sealed sample, and the maximum load was measured by peeling in a 180° direction using a universal tensile tester (manufactured by A&D Co., Ltd.) at a tensile speed of 300 mm / min in a thermostatic chamber at 23°C and 50% RH (unit: N / 15 mm). (Evaluation criteria for heat sealability) ◯: 6 N or more / 15 mm △: 4 to 6 N / 15 mm ×: 4 N or less / 15 mm

[0143] (Evaluation of Haze) The haze of the multilayer films of the Examples and Comparative Examples was measured using a haze meter (manufactured by Nippon Denshoku Kogyo Co., Ltd.) according to JIS K 7105:1981. ⊚: 8% or less ◯: 8 to 15% ×: 15% or more

[0144]

[0145]

[0146] ​​As is clear from the above table, the multilayer films of Examples 1 to 10 of the present invention were able to achieve favorable anti-fogging properties, film tearability, and heat seal strength. On the other hand, the multilayer films of Comparative Examples 1 to 5, which did not contain a polyester-based resin in the resin layer (B), had relatively good anti-fogging properties but poor film tearability and low heat seal strength. Furthermore, the multilayer films of Comparative Examples 6 and 7, which did not contain an anti-fogging agent in the seal layer (A), had poor anti-fogging properties.

Claims

1. A multilayer film comprising a sealing layer (A) and a resin layer (B) adjacent to the sealing layer (A), wherein the sealing layer (A) contains a polyester-based resin (a) and an anti-fogging agent, and the resin layer (B) contains an acid-modified polyolefin and a polyester-based resin (b).

2. The multilayer film according to claim 1, wherein the sealing layer contains polyester resins (a1) and (a2) as polyester resins, the glass transition temperature of the polyester resin (a1) being 60 to 140°C, and the glass transition temperature of the polyester resin (a2) being 45°C or lower.

3. The multi-layer film according to claim 1, wherein the glass transition temperature of the polyester resin (b) is 45° C. or lower.

4. The multilayer film according to claim 1, wherein the amount of the antifogging agent in the sealing layer (A) is 1.0 to 7.0% by mass.

5. The multilayer film according to claim 1, wherein the mass ratio of the acid-modified polyolefin to the polyester resin (b) in the resin layer (B) is 45:55 to 95:

5.

6. The multilayer film of claim 1, further comprising a laminate layer (A).

7. A laminate comprising the multilayer film according to any one of claims 1 to 6.

8. A packaging material using the laminate according to claim 7.

9. The packaging material according to claim 8, which is a lid material for a food packaging container.

10. A food packaging container using the packaging material according to claim 9 as a lid material, wherein the portion of the food packaging container that is bonded to the lid material contains a polyester-based resin.

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