TW201520044A - Antifogging multilayer film, laminate using same, and packaging material - Google Patents

Abstract

The present invention relates to a multilayer film obtained by laminating in the order (A)/(B)/(C)/(D): a laminate layer (A) having a polyolefin (a1) as a main component and not including an antifogging agent; an intermediate layer (B) containing a polyolefin (b1) and an antifogging agent (b2); an adhesive layer (C) having an acid-modified polyolefin (c1) as a main component; and a heat seal layer (D) containing a polyester resin (d1) and an antifogging agent (d2), the outer surface of the heat seal layer of the multilayer film being treated to have a wet tensile strength within the range of 50-60 mN/m, and the outer surface of the laminate layer being treated to have a wet tensile strength within the range of 35-45 mN/m.

Description

Antifogging multilayer film, laminated body using the same, and packaging material

The present invention relates to a multilayer film which can be suitably used as a covering material for a food packaging container and which has both antifogging property and easy-opening property, and a laminate body using the same.

In the past, as a package of refrigerated food such as cut vegetables or cut fruits, a polyester container excellent in transparency and recyclability has been widely used. The covering material of these packages requires antifogging property in order to improve the visibility of the contents. This is because if mist is generated on the inner surface of the packaging material due to evaporation of moisture from the refrigerated food in the container, it is difficult to see that the value of the contents and the product is lowered, that is, the consumer who cannot become safe and secure in response to the request. Demand. In addition, in the covering material of the container, it is necessary to have a certain sealing property before the contents are taken out, and on the other hand, in the general design tendency, the socially weak (aged, young, disabled, etc.) In terms of concerns, there is a growing emphasis on the way consumers open their doors, such as easy opening.

Now, as a method of imparting antifogging property to a packaging material, there is known a method of kneading an antifogging agent into a resin used for a packaging material, forming it into a film shape, and then forming it into various packaging materials by secondary molding; After molding the resin into a film shape, a method of applying an antifogging agent to a surface that is in contact with the content (for example, see Patent Document 1).

In the method of kneading the antifogging agent to the resin, in a single layer of thin In the case of a film or in the case where an anti-fogging agent is kneaded on all the layers of the multilayer film, when printing is applied to the surface thereof and bonded to other substrate films, sometimes the surface is bleed-out. The antifogging agent reacts with the printing ink or the adhesive to cause the printed surface to peel off or subsequently deteriorate. On the other hand, although an example in which an antifogging agent is kneaded on a heat seal layer is provided in the case of a multilayer film, since the antifogging agent has a property of easily moving in the multilayer film, the effect of antifogging property is not fixed. There is no problem of persistence in effect, or there is a problem that the antifogging agent is transferred to a layer adjacent to the layer containing the antifogging agent, which affects the adhesion between the layers and causes peeling.

Also, applying a coating liquid containing an antifogging agent to the surface of the film In the method, there is a problem that the drying step of the coating film is required, the production efficiency is low, and the antifogging agent on the coated surface flows due to the evapotranspiration of the moisture from the content, and the sustainability of the antifogging effect is lowered.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2004-025825

In view of the above circumstances, an object of the present invention is to provide a multilayer film which is excellent in antifogging property against fogging due to water vapor from a content, and which has excellent easy-opening property and is suitable for use as a covering material for a packaging container; And laminating the multilayer film on the substrate film The laminated body formed; and the packaging material using the same.

In order to solve the problem, the inventors of the present invention have found that at least four layers of a multilayer film composed of a layered olefin resin and a polyester resin are selected, and a layer for kneading the antifogging agent is selected, and a multilayer film is appropriately formed. The multilayer film obtained by the surface treatment can solve the above problems, and the present invention has been completed.

That is, the present invention provides an antifogging multilayer film, a laminate comprising the laminate of the base film, and a packaging material using the same, and the antifogging multilayer film is (A)/(B)/( The order of C)/(D) is a multilayer film composed of a laminate of a layer (A), an intermediate layer (B), a layer (C), and a heat seal layer (D), and the layer (A) is laminated. The olefin (a1) as a main component does not contain an antifogging agent; the intermediate layer (B) contains a polyolefin (b1) and an antifogging agent (b2); and the subsequent layer (C) is an acid-modified polyolefin (c1) The heat seal layer (D) contains a polyester resin (d1) and an antifogging agent (d2), and is characterized in that the outer surface of the heat seal layer of the multilayer film is treated to have a wetting tension of 50 to 60 mN. In the range of /m, the outer surface of the laminate layer is treated to have a wetting tension of 35 to 45 mN/m.

The anti-fog multilayer film of the present invention and the laminate using the same are heat-sealed when heat-sealed as a covering material of a polyester-based packaging container or when heat-sealed in a bag shape. (D) is a polyester-based resin as a main component, so that the polyester-based packaging container is firmly thermally fused, and when it is opened, it is easy to peel off between the layers of the heat-sealing layer (D) and the adhesive layer (C). Unsealing. In addition, since the anti-fogging property is good, it can It is suitable for use as a packaging material for frozen foods such as fruits and vegetables or cooked food.

[Formation of the Invention]

Hereinafter, each part of the anti-fogging multilayer film constituting the present invention and the laminated body using the same will be described in detail.

[Layered layer (A)]

The layered layer (A) of the present invention is characterized in that the polyolefin (a1) is mainly contained, and the layer does not contain an antifogging agent.

In the present invention, the main component is a specific resin containing 65 mass% or more, preferably 80 mass% or more, based on the total amount of the resin component forming the layer.

The polyolefin (a1) is exemplified by various ethylene resins or propylene resins, and is capable of effectively preventing the antifogging agent in the multilayer film described later from being transferred to the lamination surface and preventing peeling from the layer of the base film. From the viewpoint, it is preferred that the resin has a density of 0.880 g/cm ² or more and less than 0.960 g/cm ^{2 of} a vinyl-based resin or a propylene-α-olefin polymerized using a single-site catalyst. The copolymer is particularly preferably an ethylene resin.

Examples of the vinyl resin include ultra low density polyethylene (VLDPE), linear low density polyethylene (LLDPE), low density polyethylene (LDPE), linear medium density polyethylene (LMDPE), and medium density polyethylene. A polyethylene resin such as (MDPE) or an ethylene-vinyl acetate copolymer (EVA) may be used singly or in combination of two or more. In this Among them, LLDPE is preferred from the viewpoint of good balance between film formability and suppression of migration of the antifogging agent.

As LDPE, if it is obtained by high pressure radical polymerization In the case of the branched low-density polyethylene, it is preferably a branched low-density polyethylene obtained by polymerizing ethylene in a high-pressure radical polymerization method.

As LLDPE, the use of a single location catalyst is low A pressure radical polymerization method in which an ethylene monomer is used as a main component, and an α-olefin such as butene-1, hexene-1, octene-1, 4-methylpentene or the like as a comonomer Aggregated. The content of the comonomer in the LLDPE is preferably in the range of 0.5 to 20 mol%, more preferably in the range of 1 to 18 mol%.

As the single site catalyst, the periodic table IV A single-site catalyst such as a metallocene compound of a group V transition metal or a metallocene catalyst such as a combination of an organoaluminum compound and/or an ionic compound. Moreover, since the active sites of the single-site catalyst are averaged, the molecular weight distribution of the obtained resin is sharper than that of the multi-point catalyst having an uneven activity point, so that it is low when the film is formed into a film. A resin having a small amount of precipitation of a molecular weight component and having physical properties excellent in stability of lamination strength or blocking resistance is preferable.

As described above, the density of the vinyl resin is preferably from 0.880 to 0.960 g/cm ³ . When the density is in this range, it has moderate rigidity, excellent mechanical strength such as pinhole resistance, and improved film formability and extrusion suitability. Further, the melting point is generally preferably in the range of 60 to 130 ° C, more preferably 70 to 120 ° C. If the melting point is in this range, the processing stability (dead holding property) or the co-extrusion processability is improved. Further, the MFR (190 ° C, 21.18 N) of the vinyl resin is preferably 2 to 20 g/10 min, more preferably 3 to 10 g/10 min. If the MFR is in this range, the extrusion formability of the film is improved.

This vinyl resin can also maintain transparency at the time of lamination Sex. Moreover, since it is also flexible, the pinhole resistance is also improved.

Examples of the propylene-based resin include propylene. Polymer, propylene-α-olefin random copolymer, for example, propylene-ethylene copolymer, propylene-butene-1 copolymer, propylene-ethylene-butene-1 copolymer, metallocene catalyst polypropylene Wait. They can be used alone or in combination. A propylene-α-olefin random copolymer is desirable, and a propylene-α-olefin random copolymer polymerized using a single site catalyst is particularly preferred.

Further, these propylene-based resins are preferably MFR (230 ° C) 0.5 ~30.0g/10 minutes, the melting point is 110~165 °C, more preferably MFR (230 °C) is 2.0~15.0g/10 minutes, and the melting point is 115~162 °C. When the MFR and the melting point are in this range, the shrinkage of the covering material is small, and the film forming property of the film is also improved.

As mentioned above, the layer (A) is based on polyolefin (a1). In the case of using a binder to laminate with another substrate, or when printing or the like is applied, the adhesion to the adhesive or the printing ink is improved, and the like. Other resins can also be used in combination. In this case, as another resin which can be used in combination, an ethylene-vinyl acetate copolymer (EVA) and an ethylene-methyl methacrylate copolymer are mentioned. (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), ethylene-based copolymer such as ethylene-methacrylic acid copolymer (EMAA); and polyionic polymer (ionomer) of ethylene-acrylic acid copolymer, polyionic polymer of ethylene-methacrylic acid copolymer, etc. Further, a copolymer having a cyclic olefin structure such as a norbornene-based monomer and a copolymer of ethylene or the like may be used singly or in combination of two or more kinds.

[Intermediate layer (B)]

The intermediate layer (B) in the multilayer film of the present invention must contain a polyolefin (b1) and an antifogging agent (b2). The polyolefin (b1) can be exemplified by the same as the polyolefin (a1) used in the above-mentioned laminated layer (A), and is preferably the same. The polyolefin (a1) used in the layered layer (A) and the polyolefin (b1) used in the intermediate layer (B) may be the same or different, but from the viewpoint that peeling between layers is hard to occur, It is preferably used in combination with the same series of resins. In the case of combining the same series of resins, the density may be the same or different.

The ratio of use of the polyolefin (b1) in the intermediate layer (B) is preferably such that the resin contains a resin as a main component, and particularly preferably contains 90% by mass or more. The other types of resins that can be used in combination are the same as those exemplified as the resin which can be used in combination with the layer (A).

The anti-fogging agent (b2) is not particularly limited as long as it is added to the olefin-based resin to impart antifogging property. For example, an anionic surfactant and a nonionic interfacial activity can be used. Agent, cationic surfactant, amphoteric surfactant, etc. It is preferred to use a nonionic surfactant.

Specifically, sorbitan monostearate, mountain Pear anhydride distearate, sorbitan monopalmitate, sorbitan dipalmitate, sorbitan monocosylate, sorbitan didocate, sorbitan monolauric a sorbitol-based surfactant such as an acid ester or sorbitan dilaurate; glycerol monolaurate, glyceryl dilaurate, diglycerin monopalmitate, diglycerin dipalmitate, glyceryl monostearate Glycerin-based surfactant such as ester, glyceryl distearate, diglycerin monostearate, diglyceryl distearate, diglycerin monolaurate, diglycerin dilaurate; polyethylene glycol single a polyethylene glycol-based surfactant such as stearate or polyethylene glycol monopalmitate; a trimethylolpropane-based surfactant such as trimethylolpropane monostearate; lauryl diethanolamine or oil Interfacial activity of diethanol alkylamines and diethanol alkyl amides such as alkenyl diethanolamine, stearyl diethanolamine, lauryl diethanol decylamine, oleyl diethanol decylamine, stearyl diethanol decylamine Pentaerythritol surfactant such as pentaerythritol monopalmitate and polyoxyethylene sorbitol Monostearate, polyoxyethylene sorbitan distearate, sorbitan - diglycerol monostearate and polycondensates distearate. They can be used singly or in combination of two or more.

Use as an antifogging agent (b2) in the aforementioned intermediate layer (B) The ratio is preferably in the range of 0.5 to 4.0% by mass, particularly preferably in the range of 1.0 to 3.0% by mass, based on the total mass of the layer. By using the antifogging agent (b2) in this range, excessive migration to the above-mentioned laminated layer (A) does not occur, and it is easy to improve the antifogging property as a film.

[Next layer (C)]

The adhesive layer (C) in the multilayer film of the present invention contains the acid-modified polyolefin (c1) as a main component. The olefin component of the main component of the acid-modified polyolefin (c1) is not particularly limited, but is preferably ethylene, propylene, isobutylene, 2-butene, 1-butene, 1-pentene, 1-hexene, or the like. Alkene having 2 to 6 carbon atoms may also be used as a mixture thereof. Among them, an olefin having 2 to 4 carbon atoms such as ethylene, propylene, isobutylene or 1-butene is more preferable, and ethylene or propylene is more preferable, and ethylene is most preferable. Further, the acid-modified polyolefin (c1) must contain a (meth) acrylate component. Examples of the (meth) acrylate component include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, and (meth) acrylate. Ester, octyl (meth) acrylate, decyl (meth) acrylate, lauryl (meth) acrylate, octyl (meth) acrylate, dodecyl (meth) acrylate, stearic acid (meth) acrylate Ester and the like. From the viewpoint of easy availability and adhesion, it is more preferably methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate or hexyl (meth)acrylate, and even more preferably Methyl acrylate, ethyl acrylate. In addition, the (meth) acrylate component may be copolymerized with the olefin component, and the form thereof is not limited, and examples of the copolymerization state include random copolymerization and block copolymerization. Graft copolymerization (graft modification) and the like. (Also, "(meth)acrylic acid ~" means "acrylic acid ~ or methacrylic acid ~") Specifically, for example, as the ethylene-(meth) acrylate copolymer, ELVALOY (trade name: MJTSUI-DUPONT POLYCHEMICAL CO., LTD.), ACRYFT (trade name: manufactured by Sumitomo Chemical Co., Ltd.), etc. These may be used alone or in combination of two or more.

Moreover, the acid-modified polyolefin (c1) may also utilize unsaturated The carboxylic acid component is acid-modified. Examples of the unsaturated carboxylic acid component include acrylic acid, methacrylic acid, maleic acid, maleic anhydride, itaconic acid, itaconic anhydride, fumaric acid, crotonic acid, and the like, and a half ester of an unsaturated dicarboxylic acid. , hemi-amine and the like. Among them, acrylic acid, methacrylic acid, maleic acid, and maleic anhydride are preferred, and acrylic acid and maleic anhydride are particularly preferred. In addition, the unsaturated carboxylic acid component may be copolymerized with the olefin component, and its form is not limited. Examples of the copolymerization state include random copolymerization, block copolymerization, and graft copolymerization. Polymerization (graft modification) and the like. Specifically, examples of the ethylene-acrylic acid copolymer include NUCREL (trade name: manufactured by MITSUI-DUPONT POLYCHEMICAL CO., LTD.). The ethylene-(meth)acrylate-maleic anhydride copolymer may, for example, be BONDINE (trade name: manufactured by ARKEMA Co., Ltd.). These may be used alone or in combination of two or more.

As the acid modification ratio of the aforementioned acid-modified polyolefin (c1), From the standpoint of goodness, it is preferably 0.5 to 40%, more preferably 0.5 to 35%, and particularly preferably 0.5 to 30%.

The layer (C) in the present invention is the aforementioned acid-modified polyolefin (c1) As the main component, other resins may be used in combination as long as the adhesion of the layer (B) and the layer (D) is not impaired. In particular, a polyolefin-based resin can be used in combination from the viewpoint of being mixed with the acid-modified polyolefin (c1) and easily coextruded with the layer (B) or the layer (D).

[Heat seal layer (D)]

The heat seal layer (D) in the multilayer film of the present invention contains a polyethylene terephthalate resin (d1) and an antifogging agent (d2).

As the polyester resin (d1), it is desirable to be amorphous ( Amorphous) or low crystallinity. The polyester resin (d1) can be derived from phthalic acid, terephthalic acid, isophthalic acid, adipic acid, sebacic acid, naphthalene dicarboxylic acid, 4, 4' as a dibasic acid component. -diphenylstilbene dicarboxylic acid, 4,4'-biphenyldicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,3-phenylenedioxy diacetic acid, and their structural isomerism a component selected from the group consisting of dicarboxylic acids such as malonic acid, succinic acid, and adipic acid or derivatives thereof, oxobenzoic acid, p-hydroxybenzoic acid esters, oxyacids such as glycolic acid, or derivatives thereof, and Fat from ethylene glycol, diethylene glycol, neopentyl glycol, hexanediol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, pentanediol, etc. as a diol component a component selected from the group consisting of a group of diols, an alicyclic diol such as cyclohexanedimethanol or an aromatic dihydroxy compound derivative such as bisphenol A or bisphenol S, respectively, and one or more combinations are selected. The transesterification reaction or the esterification reaction of the carboxylic acid component and the diol component is followed by a melt polycondensation reaction.

Further, as the polyester resin (d1), a lactic acid system can also be used. The polymer is not particularly limited, and examples thereof include poly(D-lactic acid), poly(L-lactic acid), a copolymer of D-lactic acid and L-lactic acid, a copolymer of D-lactic acid and other hydroxycarboxylic acid, or a copolymer of L-lactic acid and another hydroxycarboxylic acid, or a blend thereof, or a polyester component obtained by esterifying a dicarboxylic acid and a diol with a lactic acid component, wherein From the viewpoint of film formation stability, it is particularly preferred that the main structural unit is L-lactic acid polylactic acid.

As the above hydroxycarboxylic acid, a diol, and a dicarboxylic acid, a hydroxyl group a hydroxycarboxylate such as a hydroxycaproic acid such as acetic acid, hydroxybutyric acid or hydroxycaproic acid, or a cyclic lactone such as caprolactone, butyrolactone, lactide or glycolide. Acid; aliphatic diols such as ethylene glycol, propylene glycol, 1,4-butanediol, 1,4-cyclohexanedimethanol; aromatic two of terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid, etc. An aliphatic dicarboxylic acid such as carboxylic acid; succinic acid, adipic acid, suberic acid or sebacic acid.

In particular, as the polyester resin (d1) used in the present invention, An amorphous copolymerized polyethylene terephthalate resin having a combination of a dibasic acid component and a diol component and a glass transition temperature Tg of about -20 to 80 ° C is particularly suitable.

The antifogging agent (d2) used as the heat seal layer (D) can be used It is to be noted that the antifogging agent (b2) used in the intermediate layer (B) is also the same.

Antifogging agent (b2) and heat seal layer used as intermediate layer (B) (D) The antifogging agent (d2) used may be the same or different.

Ratio of use as antifogging agent (d2) in heat seal layer (D) With respect to the total mass of the layer, it is preferably in the range of 1.5 to 2.5% by mass, particularly preferably in the range of 1.8 to 2.3% by mass. By using the antifogging agent (d2) in this range, it is easy to obtain the antifogging property and the antifogging durability which are favorable as a film.

[Anti-fog multilayer film]

The antifogging multilayer film of the present invention has the above laminated layer (A), intermediate layer (B), adhesive layer (C) and heat seal layer (D) as (A)/(B)/(C)/(D). A multilayer film that is laminated. In the layered structure of the antifogging multilayer film of the present invention, the layer (A) does not contain an antifogging agent, and the two layers of the intermediate layer (B) and the heat seal layer (D) contain an antifogging agent. The wetting tension of the outer surface of the sealing layer is 50~ 60 mN/m, the wetting tension of the outer surface of the laminate layer is 35 to 45 mN/m. The multilayer film of this constitution can achieve suitable antifogging property and can achieve a suitable adhesive strength at the time of heat sealing, and can maintain a suitable easy-opening property between (C)/(D) layers even when unsealing. Moreover, in addition to the detachment of the antifogging agent, it is difficult to stably maintain the antifogging property, and the printing or the adhesion to other substrates is also good.

As the total thickness of the antifogging multilayer film of the present invention, From the viewpoint of easy lamination in the case of laminating it with another substrate, it is preferably in the range of 20 to 100 μm, and particularly preferably in the range of 20 to 50 μm from the viewpoint of easy film formation.

Also, as the ratio of the layers in the multilayer film, from the seal From the viewpoints of properties, easy-opening properties, and lamination properties, it is preferable that the thickness ratio of the layer (A) is in the range of 20 to 30%, and the thickness ratio of the intermediate layer (B) is in the range of 30 to 40%, and heat sealing. The thickness ratio of the layer (D) is in the range of 10 to 20%.

Anti-fog multilayer film of the present invention as a whole The total amount of the aerosol is 0.7 to 1.5% by mass, and is particularly preferably in the range of 0.8 to 1.3% by mass from the viewpoint of good film formability, antifogging property, and antifogging durability.

The present invention can be carried out without departing from the scope of the present invention. Each layer (A), (B), (C), (D) of the anti-fog multilayer film is provided with an antistatic agent, a heat stabilizer, a nucleating agent, an antioxidant, a lubricant, an anti-coagulant, and a mold release agent. Agent, UV absorber, colorant and other ingredients. In particular, in order to impart processing suitability during film formation and packaging suitability of the filling machine, the friction coefficient of the film surface is 1.5 or less, and preferably 1.0. Hereinafter, it is preferred to add a lubricant, an anti-coagulant or an antistatic agent to the resin layer corresponding to the surface layer of the multilayer film.

Further, in the antifogging multilayer film of the present invention, it is necessary to The outer surfaces of the heat-treated layer are treated to a wetting tension of 50 to 60 mN/m, and the outer surface of the layer is treated to a wetting tension of 35 to 45 mN/m. Examples of such a treatment method include surface oxidation treatment such as corona discharge treatment, plasma treatment, chromic acid treatment, flame treatment, hot air treatment, and ozone-ultraviolet treatment, or surface unevenness treatment such as sand blasting. Treated for corona discharge. By performing such a surface treatment, the coating property of the ink or the adhesive becomes good in the case where the subsequent step of laminating the layer (A) of the multilayer film or applying an adhesive to laminate with the substrate is performed. It is excellent in adhesion to ink, aluminum, anchor coating agent, etc., and it becomes easy to avoid the problem of fall of an ink, vapor deposition, and delamination. Further, by treating the surface of the heat seal layer (D), the antifogging agent can be fixed to the outer surface for a relatively long period of time, and the film is excellent in antifogging property and antifogging durability. The treatment method and degree of treatment of the layered layer (A) and the heat seal layer (D) may be the same or different, but from the viewpoint of productivity, it is preferably treated by the same method.

The method of the corona discharge treatment is not particularly limited. For example, Japanese Patent Publication No. Sho 39-12838, Japanese Patent Laid-Open No. Sho 47-19824, Japanese Patent Laid-Open No. 48-28067, and Japanese Patent Laid-Open No. 52-42114 Each of the bullets is described in a processing method such as a description. As the corona discharge treatment apparatus, a SOLID-STATE CORONA processor manufactured by Pillar Co., Ltd., a LEPEL type surface treatment machine, a VETAPHON type processor, or the like can be used. The treatment can be carried out under normal pressure in air. The discharge frequency during processing is 5kV to 40kV, more preferably 10kV to 30kV, and the waveform is preferably an alternating current sine wave. The gap transparent lance of the electrode and the dielectric roller is 0.1 mm to 10 mm, more preferably 1.0 mm to 2.0 mm. The discharge is processed above the dielectric support roller disposed in the discharge zone, and the treatment amount is 0.34 kV-A-minute/m ² to 0.4 kV-A-minute/m ² , more preferably 0.344 kV-A-minute/ m ² ~ 0.38 kV - A - min / m ² .

The heat-sealing strength of the laminated film of the present invention is based on If the condition is appropriately adjusted, for example, the laminated film of the present invention is heat-sealed to A-PET sheet (softening point 77 ° C, crystallization temperature 126 ° C) for 1 second at a temperature of 170 ° C and a pressure of 0.2 MPa. The test piece having a width of 15 mm was cut out, and the maximum load at the time of peeling at a tensile speed of 300 mm/min and the peeling in the 180-degree direction in a constant temperature chamber of 23 ° C and 50% RH was preferably 4 N/15 mm or more. Good for 5N/15mm or more. Further, the upper limit of the maximum load is preferably less than 20 N/15 mm, more preferably less than 15 N/15 mm. By setting the peeling strength, peeling or peeling of the laminated film is less likely to occur, and the easy-opening property at the time of opening is particularly suitable.

As a method of producing the antifogging multilayer film of the present invention, Although not particularly limited, for example, each resin or resin mixture used for laminating layer (A), intermediate layer (B), adhesive layer (C), and heat seal layer (D) by respective extruders may be mentioned. Heating and melting, using a co-extrusion multi-layer method or a feedblock method, in a molten state, after laminating in the order of (A) / (B) / (C) / (D), using blow molding (inflation) or a T-die-cooling roll method or the like is formed into a film-like co-extrusion method. This co-extrusion method is preferable because a multilayer film which can relatively easily adjust the ratio of the thickness of each layer, is excellent in hygienic property, and is excellent in cost performance is obtained. Among them, T mode - cooling The roll method is preferable because it is easy to suppress the deterioration of the appearance of the film or the formation of an average layer structure when the resin having a different melting point or Tg is co-extruded, and it is easy to obtain a film having a suitable transparency or gloss. Moreover, the blow molding system is simple and therefore preferred, and is also suitable for a small variety of production.

The antifogging multilayer film of the present invention is produced by the above According to the method, a multilayer film which is substantially free from stretching is obtained, and thus secondary molding such as deep drawing or embossing by vacuum forming can be performed.

The antifogging multilayer film of the present invention can also be used with other substrates Material fit. The other substrate which can be used at this time is not particularly limited, but from the viewpoint of easily exhibiting the effects of the present invention, it is preferred to use a thermoplastic resin film having high rigidity and high gloss, especially by biaxial stretching. Stretched resin film. Further, in the case where the use of transparency is not required, it can be used alone or in combination with an aluminum foil.

As the stretched resin film, for example, a biaxial can be cited Stretched polyester (PET), biaxially oriented polypropylene (OPP), biaxially stretched polyamine (PA), co-extruded biaxially stretched polymer with ethylene vinyl alcohol copolymer (EVOH) as the center layer Propylene, biaxially stretched ethylene vinyl alcohol copolymer (EVOH), coextruded biaxially oriented polypropylene coated with polyvinylidene chloride (PVDC), and the like. They can be used individually or in combination.

The laminate of the present invention is obtained by using the above-mentioned antifogging property In the multilayer film, a laminate film composed of the thermoplastic resin film is laminated, and examples of the layering method include dry lamination, wet lamination, non-solvent lamination, and extrusion lamination.

There is no particular use as the above-mentioned laminated body of the present invention. However, it is suitable for use as a covering material for packaging containers used for food, medicine, industrial parts, miscellaneous goods, magazines, and the like. In particular, from the viewpoint of the balance between the easy-opening property and the seal strength, it is preferred that the outermost layer of the packaging container (the portion adjacent to the heat-sealing layer of the multilayer film of the present invention) contains a polyester-based resin.

[Examples]

Next, the present invention will be described in more detail by way of examples and comparative examples. Hereinafter, "parts" are quality standards unless otherwise specified.

(Modulation example 1) [Adjustment of anti-fogging agent masterbatch based on polyethylene terephthalate resin]

Melt-kneading amorphous polyethylene terephthalate resin [PETG6763 by EASTMAN CHEMICAL; hereinafter referred to as PETG], and 10 parts of nonionic surfactant [POEM J-4081 manufactured by Riken VITAMIN Co., Ltd.] The granules obtained antifogging masterbatch particles (hereinafter referred to as antifogging agent MB (1)).

(Modulation example 2) [Adjustment of anti-fogging masterbatch based on linear low-density polyethylene]

Melt-kneading 90 parts of linear low-density polyethylene [density 0.93g/cm ³ , melt flow rate 6g/10min; hereinafter referred to as LLDPE], and 10 parts of non-ionic surfactant [POEM by Riken VITAMIN Co., Ltd. J-4081], granulation is carried out to obtain antifogging agent masterbatch particles (hereinafter referred to as antifogging agent MB (2)).

(Modulation Example 3) [Adjustment of antifogging masterbatch based on crystalline polyester]

90 parts of crystalline polyester [VYLON GM-913, manufactured by Toyobo Co., Ltd.; hereinafter referred to as crystalline PES], and 10 parts of nonionic surfactant (POEM J-4081 manufactured by Rigaku VITAMIN Co., Ltd.) were melt-kneaded. Granulation is carried out to obtain antifogging masterbatch pellets (hereinafter referred to as antifogging agent MB (3)).

(Example 1)

As the resin for the heat seal layer (D), a mixture of 80 parts of PETG and 20 parts of the antifogging agent MB (1) (antifogging agent concentration in the heat seal layer (D): 2% by mass) was used. As the resin for the adhesive layer (C), an acid-modified ethylene-propylene-butene copolymer (hereinafter referred to as an adhesive resin 1) having an acid-modified amount of 2.9 parts and a density of 0.89 g/cm ³ was used. As the resin for the intermediate layer (B), a mixture of 80 parts of LLDPE and 20 parts of the antifogging agent MB (2) (an antifogging agent concentration in the intermediate layer (B): 2% by mass) was used. As the resin for the layered layer (A), LLDPE is used. An extruder (caliber 40 mm) for supplying the resin to the heat seal layer (D), an extruder (caliber 40 mm) for the subsequent layer (C), an extruder (caliber 50 mm) for the intermediate layer (B), and a laminate layer (A) Using an extruder (caliber 50 mm), the thickness of each layer of (A)/(B)/(C)/(D) from the T-die was 7.5/12 at a pressing temperature of 230 ° C by a co-extrusion method. Squeeze in a /6/4.5 (μm) manner and cool with a 40 ° C water-cooled metal chill roll. Next, a corona discharge treatment was applied so that the wetting tension of the heat seal layer (D) became 54 mN/m, and the wetting tension of the layer (A) was 40 mN/m, and then wound into a roll to make it roll. The ripening chamber at 35 ° C was aged for 48 hours to obtain an antifogging multilayer film of the present invention having a total thickness of 30 μm and an antifogging agent contained in the entire film of about 1.1% by mass.

(Example 2)

The antifogging amount of the entire film obtained was about 0.7% by mass in the same manner as in Example 1 except that a mixture of 90 parts of LLDPE and 10 parts of the antifogging agent MB (2) was used as the intermediate layer (B). The antifogging multilayer film of Example 2.

(Example 3)

The antifogging amount of the entire film obtained was about 1.5% by mass in the same manner as in Example 1 except that a mixture of 70 parts of LLDPE and 30 parts of the antifogging agent MB (2) was used as the intermediate layer (B). The antifogging multilayer film of Example 3.

(Example 4)

In addition to using low density polyethylene [density 0.92 g/cm ³ , melt flow rate 7 g/10 min; hereinafter referred to as LDPE] as the laminate layer (A), 80 parts of LDPE and 20 parts of melt-kneading 90 parts of LDPE were used. The antifogging multilayer film of Example 4 was obtained in the same manner as in Example 1 except that the mixture of the anti-fogging agent and the granulated masterbatch was used as the intermediate layer (B).

(Example 5)

Except that a propylene-ethylene copolymer [density 0.90 g/cm ³ , a melt flow rate of 7 g/10 min; hereinafter referred to as PP] was used as the layered layer (A), and as the intermediate layer (B), 90 parts of PP and 20 were used. The antifogging property of Example 5 was obtained in the same manner as in Example 1 except that a mixture of 90 parts of PP and 10 parts of an antifogging agent was melt-kneaded and granulated as an intermediate layer (B). Multilayer film.

(Example 6)

The antifogging multilayer film of Example 6 was obtained in the same manner as in Example 1 except that the corona discharge treatment was carried out so that the wetting tension of the heat seal layer (D) was 50 mN/m.

(Example 7)

The antifogging multilayer film of Example 7 was obtained in the same manner as in Example 1 except that the corona discharge treatment was applied so that the wetting tension of the layer (A) was 35 mN/m.

(Example 8)

An antifogging multilayer film of Example 8 was obtained in the same manner as in Example 1 except that a mixture of 80 parts of crystalline PES and 20 parts of the antifogging agent MB (3) was used as the resin for the heat seal layer (D). .

(Example 9)

The same procedure as in Example 1 was carried out except that an acid-modified ethylene polymer having an acid-modified amount of 2.5 parts and a density of 0.88 g/cm ³ (hereinafter referred to as an adhesive resin 2) was used as the resin for the adhesive layer (C). The antifogging multilayer film of Example 9 was obtained.

(Embodiment 10)

The same as in the first embodiment except that the thickness of each layer of (A)/(B)/(C)/(D) was 10/16/8/6 (μm) and the total thickness was 40 μm. The antifogging multilayer film of Example 10 was obtained.

(Comparative Example 1)

A co-extruded laminated film of Comparative Example 1 was obtained in the same manner as in Example 1 except that the corona discharge treatment of the heat-sealing layer was not carried out.

(Comparative Example 2)

A co-extruded laminated film of Comparative Example 2 was obtained in the same manner as in Example 1 except that the intermediate layer (B) was set to have only 100% LLPDE (excluding an antifogging agent).

(Comparative Example 3)

A co-extruded laminated film of Comparative Example 3 was obtained in the same manner as in Example 1 except that the heat-sealing layer (D) was made of only 100% of PETG (excluding an anti-fogging agent).

(Comparative Example 4)

A co-extruded laminate of Comparative Example 4 was obtained in the same manner as in Example 1 except that an ethylene-vinyl acetate copolymer (hereinafter referred to as EVA) having a density of 0.95 g/cm ³ was used as the resin for the adhesive layer (C). film.

(Comparative Example 5)

A coextruded laminated film of Comparative Example 5 was obtained in the same manner as in Example 1 except that a mixture of 80 parts of LLDPE and 20 parts of the antifogging agent MB (2) was used as the resin for the layered layer (A).

(Comparative Example 6)

A co-extruded laminated film of Comparative Example 6 was obtained in the same manner as in Example 1 except that the corona discharge treatment of the laminate layer was not carried out.

(Comparative Example 7)

A co-extruded laminated film of Example 7 was obtained in the same manner as in Example 1 except that the corona discharge treatment was carried out so that the wetting tension of the heat-sealing layer (D) was 45 mN/m.

The following evaluations were performed on the laminated film obtained in the above examples and comparative examples. The results obtained are shown in the table. Further, the content of the mixed components of each layer in the table is the mass ratio in the layer.

[Evaluation of anti-fog property]

A biaxially stretched polyester film having a film thickness of 12 μm was laminated on the side of the laminated layer of the obtained film using a urethane-based adhesive to form a laminated film. A heat-sealing layer of the obtained laminated film was placed in a container containing A-PET, a container having a smooth surface of 5 mm in width and having a length of 88 mm square and a capacity of 80 cm ³ in 30 ml of water at 40 ° C. The containers were put together, heat-sealed using a cup sealer, and stored at 3 ° C for 3 hours, and the antifogging effect was confirmed by visual observation according to the following criteria.

○: a continuous water film is formed on the surface of the film, and the visibility is good.

△: Visibility is good even if fine water droplets adhere to the surface of the film.

×: Water droplets adhered and visibility deteriorated

[Evaluation of heat sealability]

The heat-sealing layer of the laminated film and the A-PET sheet (softening point: 77 ° C, crystallization temperature: 126 ° C) were combined together, and a precision heat sealer (manufactured by TESTER Co., Ltd.) was used at a temperature of 170 ° C and a pressure of 0.2 MPa. After sealing for 1 second with a sealing bar having a width of 10 mm, the film was allowed to cool, and then a test piece having a width of 15 mm was cut out from the heat-sealed sample, and stretched in a constant temperature chamber at 23 ° C and 50% RH. The maximum load was measured by peeling in a 180-degree direction using a universal tensile tester (manufactured by A&D Co., Ltd.) under the conditions of a speed of 300 mm/min. From the value of the obtained seal strength (unit: N/15 mm), the heat sealability was evaluated in accordance with the following criteria.

○: The sealing strength before heating is 4N/15mm or more and less than 20N/15mm

×: The sealing strength before heating is less than 4N/15mm, 20N/15mm or more

[Stratified evaluation]

When the above sealing property evaluation was carried out, it was confirmed whether or not delamination occurred between the biaxially stretched polyester film and the multilayer film.

○: no stratification

×: There is stratification

As can be seen from the above table, the inventions of Examples 1 to 10 The antifogging laminated film can achieve suitable antifogging property and heat sealability. Further, it has a problem of suitable lamination strength and practically does not cause delamination. On the other hand, the laminated film of Comparative Examples 1 to 7 could not achieve both suitable antifogging property and heat sealability.

Claims (13)

An anti-fog multilayer film in which the layer (A), the intermediate layer (B), the adhesive layer (C), and the heat seal layer are laminated in the order of (A) / (B) / (C) / (D) D) a multilayer film comprising a laminate comprising a polyolefin (a1) as a main component and containing no antifogging agent; the intermediate layer (B) comprising a polyolefin (b1) and an antifogging agent (b2) The adhesive layer (C) contains an acid-modified polyolefin (c1) as a main component; the heat seal layer (D) contains a polyester resin (d1) and an anti-fogging agent (d2), and is characterized by: The wetting tension of the outer surface of the heat-sealing layer of the multilayer film is 50 to 60 mN/m, and the wetting tension of the outer surface of the layer is 35 to 45 mN/m. The anti-fog multilayer film of claim 1, wherein the total mass of the anti-fogging agent (b2) and the anti-fogging agent (d2) is in a range of 0.7 to 1.5% by mass based on the total mass of the multilayer film. . The antifogging multilayer film according to claim 1 or 2, wherein the polyolefins (a1) and (b1) are vinyl resins. The antifogging multilayer film according to any one of claims 1 to 3, wherein the polyester resin (d1) is an amorphous polyester resin. The anti-fog multilayer film according to any one of claims 1 to 4, wherein the total thickness of the multilayer film is in the range of 20 to 100 μm. The anti-fog multilayer film according to any one of claims 1 to 5, wherein a thickness ratio of the layer (A) is in a range of 10 to 30% with respect to the total thickness of the multilayer film, and a thickness of the intermediate layer (B) The ratio is in the range of 30 to 50%, and the thickness ratio of the heat seal layer (D) is in the range of 10 to 20%. The antifogging multilayer film according to any one of claims 1 to 6, wherein the multilayer film is produced by a co-extrusion lamination method. The antifogging multilayer film according to any one of claims 1 to 7, wherein the treatment is a corona discharge treatment. The antifogging multilayer film according to any one of claims 1 to 8, wherein the antifogging agents (b2) and (d2) are nonionic surfactants. A laminate comprising a layer (A) of an antifogging multilayer film according to any one of claims 1 to 9 and a thermoplastic resin film layer. A packaging material characterized by using a laminate as claimed in claim 10. The packaging material of claim 11, which is a covering material for a food packaging container. The packaging material of claim 12, wherein the sealing surface of the food packaging container is a resin layer containing a polyester resin.