JP2018099842A - Antifogging multilayer film, laminate using the same, and packaging material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multilayer film which is excellent in discharge stability at the time of film production, is excellent in sustainability and stability of antifogging properties for preventing fogging caused by water vapor from a content, has excellent laminate strength, and is suitable for application of a lid material of a packaging container.SOLUTION: An antifogging multilayer film formed by laminating a laminate layer (A), which contains a polypropylene-based resin (a) and contains no antifogging agent, an intermediate layer (B1) containing linear polyethylene (b11) and an antifogging agent (b12) and a heat seal layer (C) containing linear polyethylene (c11) and an antifogging agent (c12) in order of (A)/(B1)/(C), can achieve preferable antifogging properties and excellent laminate strength.SELECTED DRAWING: None

Description

  The present invention relates to a multilayer film having excellent laminate strength, antifogging property, and easy-opening property, and a laminate using the same, which can be suitably used as a lid for food packaging containers.

  In recent years, in the food packaging market, for example, in order to improve the visibility of contents such as fruits and vegetables, side dishes, meat, etc., anti-fogging properties are required for packaging materials. This is because if the moisture content from the fruits, vegetables, and meat in the container causes turbidity on the inner surface of the packaging material, the contents are difficult to see and the product value is lowered, that is, consumers seeking food safety and security. This is because it is impossible to meet the demands of

  Currently, as a method for imparting antifogging properties to a packaging material, a method for producing a lid film that is opened using a raw material kneaded in a resin that uses an antifogging agent for the packaging material (Patent Document 1), a resin A method of applying an antifogging agent to at least the surface in contact with the contents after being formed into a film is known (for example, see Patent Document 2).

Japanese Patent Laid-Open No. 04-047936 JP 09-248880 A

  In the method of kneading the antifogging agent into the resin, in the case of a single layer film or when the antifogging agent is kneaded in all layers of the multilayer film, the surface of the antifogging agent is printed or bonded to another base film. In some cases, the antifogging agent that bleeds out on the surface reacts with the printing ink or adhesive to cause peeling of the printed surface or poor adhesion. In the case of a multilayer film, an example in which an antifogging agent is kneaded only in a specific layer is also provided, but the antifogging effect is not constant because the antifogging agent has a property of easily moving in the multilayer film. In addition, there is a problem that the effect is not sustainable, and when the amount of the antifogging agent is increased, ejection failure occurs.

  In view of the above circumstances, the object of the present invention is excellent in ejection stability during film production, and has excellent anti-fogging durability and stability to prevent fogging due to water vapor from the contents, and an excellent laminate An object of the present invention is to provide a multilayer film having strength and suitable for uses such as a lid for a packaging container, a laminate obtained by laminating the multilayer film on a base film, and a packaging material using the same.

  As a result of diligent research to solve such a problem, the present inventor has selected at least three layers of multilayer films obtained by laminating a polypropylene resin and a polyethylene resin, and selects a layer for kneading an antifogging agent. It discovered that the multilayer film obtained by performing appropriately can solve the said subject, and completed this invention.

  That is, the present invention includes a laminate layer (A) containing a polypropylene resin (a) and no antifogging agent, and an intermediate layer (B1) containing a linear polyethylene (b11) and an antifogging agent (b12). ), And a heat seal layer (C) containing linear polyethylene (c11) and an antifogging agent (c12) are laminated in the order of (A) / (B1) / (C). In addition, the total mass of the antifogging agent (b12) and the antifogging agent (c12) is included in the range of 0.2 to 1.0 mass% with respect to the total mass of the multilayer multilayer film. The present invention provides a multilayer film, a laminate obtained by laminating the multilayer film and a base film, and a packaging material using the same.

  Since the anti-fogging multilayer film of the present invention and the laminate using the same have excellent laminate strength and anti-fogging properties at the same time, it can be suitably used as a packaging material for fruits and vegetables, vegetables, and meat.

  Below, each part which comprises the anti-fogging multilayer film of this invention and a laminated body using this is explained in full detail.

[Laminate layer (A)]
The laminate layer (A) of the present invention contains a polypropylene resin (a), and the layer does not contain an antifogging agent.

  In the present invention, the laminate layer (A) preferably contains 65% by mass or more, more preferably 80% by mass or more of the polypropylene resin (a) with respect to the total amount of the resin components forming the layer. .

  The polypropylene resin (a) is not particularly limited as long as it can be laminated with the intermediate layer (B). For example, propylene homopolymer, propylene-ethylene copolymer, propylene-butene-1 Examples thereof include propylene / α-olefin random copolymers such as copolymers and propylene-ethylene-butene-1 copolymers, and metallocene catalyst polypropylene. These may be used alone or in combination.

  The polypropylene resin (a) preferably has an MFR (230 ° C.) of 0.5 to 30.0 g / 10 minutes and a melting point of 110 to 165 ° C., more preferably MFR (230 ° C.). The melting point is 115 to 162 ° C. at 2.0 to 15.0 g / 10 minutes. If MFR and melting | fusing point are this range, process stability, the workability at the time of coextruding with another layer, and the film-forming property of a film will also improve.

  As described above, the laminate layer (A) is mainly composed of the polypropylene resin (a). However, when laminating with another base material and an adhesive, or when printing is performed. From the viewpoint of the purpose of improving the adhesion with an adhesive or printing ink, other resins may be used in combination. Examples of other resins that can be used at this time include linear polyethylene such as linear low density polyethylene (LLDPE) and low density polyethylene (LDPE), branched polyethylene, 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 copolymers such as ethylene-acrylic acid copolymer (EAA), ethylene-methacrylic acid copolymer (EMAA); further, ionomers of ethylene-acrylic acid copolymers, ethylene-methacrylic acid copolymers Combined ionomers and cyclic olefins such as norbornene monomers Copolymers of monomers and ethylene, and the like having a down structure, alone, may be used by mixing two or more kinds.

  When these other resins are used, it is preferably 35% by mass or less, more preferably 20% by mass or less, based on the total amount of the resin components forming the laminate layer (A). The lower limit is not particularly limited, but may be appropriately used at a content of 1% by mass or more according to desired properties.

[Intermediate layer (B1)]
The intermediate layer (B1) in the multilayer film of the present invention is a layer containing linear polyethylene (b11) and an antifogging agent (b12), and is a layer directly laminated with the heat seal layer (C) described later. is there.

  As the linear polyethylene (b11), an ethylene monomer as a main component and a butene-1, hexene-1, octene-1, 4-methyl as a comonomer by a low-pressure radical polymerization method using a single site catalyst are used. Copolymerized with α-olefin such as pentene. As a comonomer content rate in linear polyethylene (b11), it is preferable that it is the range of 0.5-20 mol%, and it is more preferable that it is the range of 1-18 mol%.

  Examples of the single-site catalyst include various single-site catalysts such as metallocene catalyst systems such as combinations of metallocene compounds of Group IV or V transition metals and organoaluminum compounds and / or ionic compounds. In addition, the single-site catalyst has a uniform active site, so the molecular weight distribution of the resulting resin is sharper than a multi-site catalyst with a non-uniform active site. This is preferable because a resin having physical properties excellent in stability of sealing strength and anti-blocking property can be obtained.

Density linear polyethylene (b11) is preferably from 0.900~0.945g / cm ^3, more preferably 0.910~0.940g / cm ^3. If the density is within this range, it has moderate rigidity, excellent mechanical strength such as heat seal strength and pinhole resistance, and film film formability and extrusion suitability are improved. Moreover, since it is easy to obtain suitable antifogging property etc., the density of the linear polyethylene (b11) used for an intermediate | middle layer (B1) is higher than the linear polyethylene (c11) used for a heat seal layer (C). Is preferably high. Moreover, it is preferable that melting | fusing point is generally the range of 60-130 degreeC, and 70-120 degreeC is more preferable. When the melting point is within this range, the processing stability and the coextrusion processability with the layer (A) are improved and the flexibility is also improved, so that the pinhole resistance is also improved. Moreover, it is preferable that it is 2-20 g / 10min, and, as for MFR (190 degreeC, 21.18N) of ethylene resin, it is more preferable that it is 3-10 g / 10min. When the MFR is within this range, the extrusion moldability of the film is improved.

  The proportion of the linear polyethylene (b11) used in the intermediate layer (B1) is preferably based on the resin, and is contained at 70% by mass or more in the resin component included in the intermediate layer (B1). It is preferable that it is 80 mass% or more, and it is more preferable that it is 90 mass% or more.

  Further, in the intermediate layer (B1), other resins other than the linear polyethylene (b11) may be used in combination. As other resin types that can be used in combination, those exemplified as polyethylene resins other than linear polyethylene that can be used in the laminate layer (A), polypropylene resins, and resins that can be used in combination can be preferably used.

  When these other resins are used, it is preferably 30% by mass or less, more preferably 20% by mass or less, and more preferably 10% by mass or less in the resin component contained in the intermediate layer (B1). It is more preferable. The lower limit is not particularly limited, but may be appropriately used at a content of 1% by mass or more according to desired properties.

  The antifogging agent (b12) is not particularly limited as long as it is generally added to an olefin resin and is known to impart antifogging properties. For example, an anionic surfactant Agents, nonionic surfactants, cationic surfactants, amphoteric surfactants, and the like can be used, and nonionic surfactants are preferably used.

  Specifically, sorbitan surfactants such as sorbitan monostearate, sorbitan distearate, sorbitan monopalmitate, sorbitan dipalmitate, sorbitan monobehenate, sorbitan dibehenate, sorbitan monolaurate, sorbitan dilaurate; Glycerol monolaurate, glycerol dilaurate, diglycerol monopalmitate, diglycerol dipalmitate, glycerol monostearate, glycerol distearate, diglycerol monostearate, diglycerol distearate, diglycerol monolaurate, diglycerol Glycerin surfactants such as dilaurate; Polyethylene glycol surfactants such as polyethylene glycol monostearate and polyethylene glycol monopalinate; Trimethylolpropane surfactants such as methylolpropane monostearate; diethanolalkylamine and diethanolalkylamide surfactants such as lauryl diethanolamine, oleyl diethanolamine, stearyl diethanolamine, lauryl diethanolamide, oleyl diethanolamide, stearyl diethanolamide; Pentaerythritol surfactants such as pentaerythritol monopalmitate and polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan distearate, mono and distearate of sorbitan-diglycerin condensate, and the like. These may be used alone or in combination of two or more.

  The use ratio of the antifogging agent (b12) in the intermediate layer (B1) is preferably in the range of 0.5 to 3.5% by mass, particularly 1.0 to 1.0% with respect to the total mass of the layer. The range is preferably 3.0% by mass. By using the antifogging agent (b2) in this range, it becomes easy to improve the antifogging property as a film without causing excessive transfer to the laminate layer (A). Moreover, it becomes easy to ensure suitable discharge stability.

[Intermediate layer (B2)]
The multilayer film of the present invention further has an intermediate layer (B2) containing linear polyethylene (b21) and is laminated in the order of (A) / (B2) / (B1) / (C). Is also preferable.

In the case of having two or more intermediate layers (B), the density of the linear polyethylene contained in the layer (B1) is in the range of 0.900 to 0.945 g / cm ³ , and the layer (B2) The density of the linear polyethylene (b21) contained in the resin is in the range of 0.900 to 0.930 g / cm ³ so that the antifogging property as a multilayer film, the adhesion to the laminate layer, and the laminate layer From the point which is excellent in the balance of migration control of the antifogging agent. When the intermediate layer (B2) is used, the resin density of the intermediate layer (B2) is the resin used for the intermediate layer (B1) because it is easy to obtain suitable adhesion between layers and good antifogging properties. It is preferably smaller than the density and larger than the resin density used for the heat seal layer (C). The resin density of each layer refers to the average density of all resins used. Preferred conditions for the linear polyethylene (b21) are the same as those exemplified for the linear polyethylene (b11) used for the intermediate layer (B1) except for the density condition.

  Moreover, as a use ratio of the said linear polyethylene (b21) in an intermediate | middle layer (B2), other resin which can be used together in an intermediate | middle layer (B2), and preferable conditions of the content, the said intermediate | middle layer (B1) The conditions are the same as those exemplified above.

  In the intermediate layer (B2), when obtaining higher antifogging property, it may contain an antifogging agent as in the intermediate layer (B1), but when it contains an antifogging agent, It is preferable that it is 2.0 mass% or less with respect to the total mass of the said intermediate | middle layer (B2), it is preferable that it is 1.0 mass%, and it is more preferable that it is 0.5 mass% or less. Moreover, when it is desired to improve the laminate strength, it is preferable that the intermediate layer (B2) does not contain an antifogging agent.

[Heat seal layer (C)]
The heat seal layer (C) in the multilayer film of the present invention contains linear polyethylene (c11) and an antifogging agent (c12).

As the linear polyethylene resin (c11), the density of the linear polyethylene is 0.880 to 0.930 g / cm because it is easy to realize a suitable sealing property while ensuring good antifogging properties. Those in the range of ³ can be preferably used, and those in the range of 0.890 to 0.930 g / cm ³ are more preferable. Preferred conditions for the linear polyethylene (b21) are the same as those exemplified for the linear polyethylene (b11) used for the intermediate layer (B1) except for the density condition.

  The proportion of the linear polyethylene-based resin (c11) used in the heat seal layer (C) is preferably based on the resin, and particularly 80 mass in the resin component contained in the heat seal layer (C). % Or more, preferably 85% by mass or more, and more preferably 90% by mass or more. As other resin types that can be used in combination, those exemplified as polyethylene resins and polypropylene resins other than linear polyethylene that can be used in the laminate layer (A) can be preferably used.

  As the antifogging agent (c12) used for the heat seal layer (C), any of those exemplified as the antifogging agent (b12) used for the intermediate layer (B) can be used, and suitable ones are also the same. .

  The antifogging agent (b12) used for the intermediate layer (B1) and the antifogging agent (c12) used for the heat seal layer (C) may be the same or different. In the case of using a masterbatch antifogging agent, the base resin is preferably a polyethylene resin from the viewpoint of compatibility.

  The use ratio of the antifogging agent (c12) in the heat seal layer (C) is preferably in the range of 1.0 to 3.5% by mass, particularly 1.5 to 3%, based on the total mass of the layer. The range is preferably 0.0 mass%. By using the antifogging agent (c12) within this range, it becomes easy to obtain a film having good antifogging properties and antifogging durability. Moreover, it is excellent in discharge stability.

[Multilayer film]
The antifogging multilayer film of the present invention has a laminate layer (A) containing the above polypropylene resin as one surface layer, and the other surface layer is a heat seal layer (C) containing linear polyethylene and an antifogging agent. It is the structure which has the intermediate | middle layer (B1) containing an antifogging agent as a layer adjacent to the said heat seal layer (C). The anti-fogging multilayer film of the present invention can be suitably applied to uses such as lids for packaging containers because it can maintain good laminate strength while having suitable anti-fogging properties and anti-fogging durability due to the configuration. .

  The antifogging multilayer film of the present invention has a configuration in which the laminate layer (A), the intermediate layer (B1), and the heat seal layer (C) are laminated in the order of (A) / (B1) / (C). A configuration in which the intermediate layer (B2) is further laminated in the order of (A) / (B2) / (B1) / (C) can be preferably exemplified. In the anti-fogging multilayer film of the present invention, a structure in which these layers are directly laminated can be preferably used, but the layer between (A) / (B1) and (A) / (B2) / (B1). Other functional layers may be laminated. Examples of the other functional layers include a gas barrier layer and (I) an adhesive layer.

  The total thickness of the multilayer film of the present invention is preferably in the range of 20 to 100 μm, particularly 20 to 50 μm from the viewpoint of easy lamination when used by being laminated with another substrate. The range is preferable from the viewpoint of easy film formation.

  Moreover, as a ratio of each layer in the multilayer film, the thickness ratio of the laminate layer (A) is in the range of 10 to 60% of the total thickness of the multilayer film from the viewpoints of sealing properties, easy opening properties, and laminating properties. Preferably, it is 20 to 50%. Further, the thickness ratio of the heat seal layer (C) is preferably in the range of 5 to 30%, more preferably in the range of 5 to 20%. Further, the thickness ratio of the intermediate layer (B1) is preferably 10 to 85%, and more preferably 10 to 75%. In addition, when using an intermediate | middle layer (B2), it is preferable to make the total thickness of an intermediate | middle layer (B1) and an intermediate | middle layer (B2) into the said thickness ratio, and the ratio of intermediate | middle layer (B1) / (B2) is A range of 1/1 to 1/5 is preferable.

  As a specific thickness, the thickness of the laminate layer (A) is preferably 2 to 60 μm, and more preferably 4 to 50 μm. The thickness of the intermediate layer (B1) is preferably 2 to 45 μm, and more preferably 2 to 40 μm. The thickness of the intermediate layer (B2) is preferably 2 to 30 μm, and more preferably 5 to 25 μm. The thickness of the heat seal layer (C) is preferably 1 to 30 μm, and more preferably 1 to 20 μm.

  The total amount of the antifogging agent contained in the entire antifogging multilayer film of the present invention is 0.2 to 1.0% by mass, particularly 0.3 to 0.8% by mass. It is preferable from the viewpoints of good film properties, antifogging properties, and antifogging durability. In particular, it is preferable that the antifogging agent is contained only in the intermediate layer (B1) and the heat seal layer (C) in this amount, and the content of the antifogging agent in the intermediate layer (B1) and the heat seal layer ( The mass ratio (B1) / (C) of the content of the antifogging agent in C) is preferably 1/3 to 2/1, and more preferably 1/2 to 1/1.

  In each layer (A), (B1), (B2) and (C) of the antifogging multilayer film of the present invention, an antistatic agent, a heat stabilizer, a nucleating agent, an antioxidant, a lubricant, an antiblocking agent, Components such as a release agent, an ultraviolet absorber, and a colorant can be added within a range that does not impair the object of the present invention. In particular, the film surface has a coefficient of friction of 1.5 or less, particularly 1.0 or less in order to impart processing suitability during film forming and packaging suitability of a filling machine, and thus corresponds to the surface layer of a multilayer film. It is preferable to add a lubricant, an antiblocking agent and an antistatic agent to the resin layer as appropriate. The content of these additives in each layer of the antifogging multilayer film is preferably 5% by mass or less, and more preferably 3% by mass or less. Therefore, the content of the resin component in each layer (when the antifogging agent is included, the total content of the resin component and the antifogging agent) is preferably 95% by mass or more, and 97% by mass or more. It is more preferable.

  In the anti-fogging multilayer film of the present invention, both outer surfaces of the film are treated so that the surface wet tension is in the range of 35 to 45 mN / m, preferably in the range of 38 to 42 mN / m. Examples of such treatment methods include corona discharge treatment, plasma treatment, chromic acid treatment, flame treatment, hot air treatment, surface oxidation treatment such as ozone / ultraviolet treatment, and surface unevenness treatment such as sandblasting. The corona discharge treatment is preferable. By performing such a surface treatment, the coating property of ink or adhesive when a post-process such as printing or applying an adhesive to the laminate layer (A) of the multilayer film and laminating it with a substrate is performed. It is excellent in adhesion with ink, aluminum, anchor coating agent, etc., and it is easy to avoid problems such as ink dropping or vapor deposition aluminum falling off or delamination. Further, by treating the surface of the heat seal layer (C), the antifogging agent can be fixed to the outer surface for a relatively long period of time, and the film has excellent antifogging properties and antifogging durability. The treatment method and treatment degree of the laminate layer (A) and the heat seal layer (C) may be the same or different, but from the viewpoint of productivity, the treatment is preferably carried out by the same method.

The method of corona discharge treatment is not particularly limited. For example, each of JP-B-39-12838, JP-A-47-19824, JP-A-48-28067, and JP-A-52-42114. It can be performed by a processing method described in the publication. As the corona discharge treatment apparatus, a solid state corona treatment machine manufactured by Pillar, a LEPEL type surface treatment machine, a VETAPHON type treatment machine, or the like can be used. The treatment can be performed at normal pressure in air. The discharge frequency during the treatment is 5 kV to 40 kV, more preferably 10 kV to 30 kV, and the waveform is preferably an alternating sine wave. The gap transparent lance between the electrode and the dielectric roll is 0.1 mm to 10 mm, more preferably 1.0 mm to 2.0 mm. The discharge is processed above a dielectric support roller provided in the discharge zone, and the treatment amount is 0.34 kV · A · min / m ^{2 to} 0.4 kV · A · min / m ² , more preferably 0.344 kV. A · min / m ^{2 to} 0.38 kV · A · min / m ² .

  Although it does not specifically limit as a manufacturing method of the anti-fogging multilayer film of this invention, For example, each resin or resin mixture used for a laminate layer (A), an intermediate | middle layer (B1), and a heat seal layer (C) is each separately. (A) / (B1) / (C) or (A) / (B2) / (B1) / () in a molten state by a method such as a coextrusion multilayer die method or a feed block method. Examples include a coextrusion method in which the layers are laminated in the order of C) and then formed into a film by inflation, a T-die / chill roll method, or the like. This coextrusion method is preferable because the thickness ratio of each layer can be adjusted relatively freely, and a multilayer film excellent in hygiene and cost performance can be obtained. In addition, since the linear polyethylene and the polypropylene resin used in the present invention have a difference in melting point or Tg between the two, the appearance of the film deteriorates during coextrusion processing, and it becomes difficult to form a uniform layer structure. There is a case. In order to suppress such deterioration, a T-die / chill roll method that can perform melt extrusion at a relatively high temperature is preferable.

  Since the antifogging multilayer film of the present invention is obtained as a substantially unstretched multilayer film by the above production method, secondary molding such as deep drawing by vacuum molding or embossing is also possible.

  The antifogging multilayer film of the present invention can also be used by being bonded to another substrate. Other substrates that can be used at this time are not particularly limited, but from the viewpoint of easily manifesting the effects of the present invention, a thermoplastic resin film having high rigidity and high gloss, particularly two It is preferable to use an axially stretched resin film. For applications that do not require transparency, aluminum foils can be used alone or in combination.

  Examples of the stretched resin film include coextrusion using, as a central layer, biaxially stretched polyester (PET), biaxially stretched polypropylene (OPP), biaxially stretched polyamide (PA), and ethylene vinyl alcohol copolymer (EVOH). Examples thereof include biaxially stretched polypropylene, biaxially stretched ethylene vinyl alcohol copolymer (EVOH), and coextruded biaxially stretched polypropylene coated with polyvinylidene chloride (PVDC). These may be used alone or in combination.

  The laminate of the present invention is a laminate film obtained by laminating the thermoplastic resin film on the antifogging multilayer film obtained as described above, and examples of the lamination method include dry lamination, wet lamination, non-solvent lamination, Examples thereof include extrusion lamination.

  Examples of the adhesive used in the dry lamination include a polyester-polyurethane adhesive. Various pressure-sensitive adhesives can be used, but a pressure-sensitive pressure-sensitive adhesive is preferably used. Examples of the pressure-sensitive adhesive include, for example, a polyisobutylene rubber, a butyl rubber, a rubber adhesive in which a mixture thereof is dissolved in an organic solvent such as benzene, toluene, xylene, hexane, or a bisethylene acid rosin in the rubber adhesive. A blend of tackifiers such as ester, terpene / phenol copolymer, terpene / indene copolymer, or 2-ethylhexyl acrylate / n-butyl acrylate copolymer, 2-ethylhexyl acrylate / ethyl acrylate / Examples thereof include an acrylic pressure-sensitive adhesive prepared by dissolving an acrylic copolymer having a glass transition point of −20 ° C. or less such as a methyl methacrylate copolymer in an organic solvent.

  Although it does not specifically limit as a use of the anti-fogging multilayer film of this invention, It can be used suitably for the lid | cover material etc. of a packaging container used for uses, such as a foodstuff, a chemical | medical agent, an industrial part, miscellaneous goods, a magazine. In particular, it is preferable that the outermost layer of the packaging container (the portion to be bonded to the heat seal layer of the multilayer film of the present invention) contains various ethylene-based resins from the viewpoint of the balance between easy opening and sealing strength.

  Next, the present invention will be described in more detail with reference to examples and comparative examples. Hereinafter, unless otherwise specified, “part” is based on mass.

Example 1
As a resin for the heat seal layer (C), linear low density polyethylene [density: 0.920 g / cm ³ , MFR: 5 g / 10 min (190 ° C., 21.18 N); hereinafter, “LLDPE (1)” Say. ] Using a mixture of 85% by mass and 15% by mass of an antifogging agent master batch (LM-590 made by Takemoto Yushi, 15% by mass of antifogging agent), as a resin for the intermediate layer (B1), linear low density polyethylene [Density: 0.935 g / cm ³ , MFR: 5 g / 10 min (190 ° C., 21.18 N); hereinafter referred to as “LLDPE (2)”. ] Using a mixture of 90% by mass and 10% by mass of the antifogging agent master batch, and using a resin composition of 50% by mass of LLDPE (1) and 50% by mass of LLDPE (2) as the intermediate layer (B2), a laminate layer (A ), A propylene homopolymer [density: 0.90 g / cm ³ , MFR: 7.5 g / 10 min] was used. The antifogging agent concentration of the entire multilayer film ((total amount of antifogging agent contained in the entire multilayer film) is 0.44% by mass.

  Extruder for heat seal layer (C) (caliber 40 mm), extruder for intermediate layer (B2) (caliber 40 mm), extruder for intermediate layer (B1) (caliber 50 mm), and extruder for laminate layer (A) ( Resin is supplied to each of the diameters of 50 mm) and the thickness of each layer of (A) / (B2) / (B1) / (C) is 9 μm / 10 μm / 3 from the T die at an extrusion temperature of 250 ° C. by coextrusion method. Extruded to a thickness of 5 μm / 2.5 μm, cooled with a 40 ° C. water-cooled metal cooling roll, subjected to corona discharge treatment on the laminate layer, wound on a roll, and aged in a aging room at 38 ° C. for 24 hours, A multilayer film of the present invention having a total thickness of 25 μm was obtained. Thereafter, a biaxially stretched polyester film 12 μm was bonded with Dick Dry LX510 / KR90 adhesive.

(Example 2)
A multilayer film of Example 2 is obtained in the same manner as in Example 1 except that a mixture of 87% by mass of LLDPE (2) and 13% by mass of an antifogging agent masterbatch is used as the resin for the intermediate layer (B1). It was. The antifogging agent concentration of the entire film layer is 0.50% by mass.

(Example 3)
The multilayer film of Example 3 was used in the same manner as in Example 1 except that as the resin for the heat seal layer (C), a mixture comprising 87% by weight of LLDPE (1) and 13% by weight of an antifogging agent masterbatch was used. Got. The antifogging agent concentration of the entire film layer is 0.41% by mass.

Example 4
Except that the layers (A) / (B2) / (B1) / (C) were extruded to have a thickness of 9 μm / 11.25 μm / 3.5 μm / 1.25 μm, the same as in Example 2. A multilayer film of Example 4 was obtained. The antifogging agent concentration of the entire film layer is 0.39% by mass.

(Example 5)
As a resin for the heat seal layer (C), a mixture of 87% by weight of LLDPE (1) and 13% by weight of an antifogging agent masterbatch was used, and as a resin of the intermediate layer (B1), 92% by weight of LLDPE (2) A multilayer film of Example 5 was obtained in the same manner as in Example 1, except that a mixture of 8% by weight of the antifogging agent master batch was used. The antifogging agent concentration of the entire film layer is 0.36% by mass.

(Example 6)
As a resin for the heat seal layer (C), a mixture of 80% by weight of LLDPE (1) and 20% by weight of an antifogging agent master batch was used, and as a resin of the intermediate layer (B1), 80% by weight of LLDPE (2) A multilayer film of Example 6 was obtained in the same manner as in Example 1 except that a mixture of 20% by weight of the antifogging agent master batch was used. The antifogging agent concentration of the entire film layer is 0.72% by mass.

(Comparative Example 1)
A multilayer film of Comparative Example 1 was obtained in the same manner as in Example 1 except that LLDPE (2) was used as the resin for the laminate layer (A). The antifogging agent concentration of the entire film layer is 0.44% by mass.

(Comparative Example 2)
A multilayer film of Comparative Example 2 was obtained in the same manner as in Example 2 except that LLDPE (2) was used as the resin for the laminate layer (A). The antifogging agent concentration of the entire film layer is 0.50% by mass.

(Comparative Example 3)
As the resin for the intermediate layer (B1), LLDPE (2) 100% by weight was used, and the thickness of each layer (A) / (B2) / (B1) / (C) was 9 μm / 7.5 μm / 5 μm / 3. A multilayer film of Comparative Example 3 was obtained in the same manner as in Example 1 except that the film was extruded to 5 μm. The antifogging agent concentration of the entire film layer is 0.32% by mass.

(Comparative Example 4)
As the resin for the intermediate layer (B1), LLDPE (2) 100 wt% was used, and the thickness of each layer (A) / (B2) / (B1) / (C) was 9 μm / 7.5 μm / 3.5 μm / A multilayer film of Comparative Example 4 was obtained in the same manner as in Example 1 except that the film was extruded to 5 μm. The antifogging agent concentration of the entire film layer is 0.45% by mass.

(Comparative Example 5)
As a resin for the intermediate layer (B1), 100% by mass of LLDPE (2) is used, and as a resin for the heat seal layer (C), a mixture of 80% by mass of LLDPE (1) and 20% by mass of an antifogging agent master batch. The same procedure as in Example 1 was conducted except that the thickness of each layer (A) / (B2) / (B1) / (C) was 9 μm / 7.5 μm / 5 μm / 3.5 μm. A multilayer film of Comparative Example 5 was obtained. The antifogging agent concentration of the entire film layer is 0.42% by mass.

(Comparative Example 6)
As a resin for the intermediate layer (B1), 100% by mass of LLDPE (2) is used, and as a resin for the heat seal layer (C), a mixture of 75% by mass of LLDPE (1) and 25% by mass of an antifogging agent masterbatch is used. The same procedure as in Example 1 was conducted except that the thickness of each layer (A) / (B2) / (B1) / (C) was 9 μm / 7.5 μm / 5 μm / 3.5 μm. A multilayer film of Comparative Example 6 was obtained. The antifogging agent concentration of the entire film layer is 0.53% by mass.

  In the examples and comparative examples, the following evaluation was performed. The obtained results are shown in the table.

<Discharge stability during film formation>
The ejection stability during the production of the multilayer film was evaluated according to the following criteria.
○: Discharge amount stable ×: Discharge unstable due to surging

<Anti-fogging property>
The multilayer films obtained in Examples and Comparative Examples were bonded to a biaxially stretched polyester film 12 μm with a polyurethane-based dry laminate adhesive (Dick Dry LX510 / KR90) and subjected to aging in a 38 ° C. environment for 24 hours. The obtained laminate film was cut into 8 cm × 8 cm, and 50 ml of water at 60 ° C. was put into a 100 ml 71φ injection container with an autocup sealer and heat sealed (pressure 64 kgf / cup, temperature 150 ° C., time 1.0 sec. ), And stored for 3 hours at 3 ° C. in a low temperature room using the following criteria to confirm the anti-fogging effect.
○: A continuous water film is formed on the surface of the film, and visibility is good.

<Lamination strength>
The laminate strength of the laminate film obtained by the above antifogging evaluation was evaluated according to the following criteria. Regarding the behavior of the laminate strength between the polyester film and the multilayer films obtained in the examples and comparative examples, when peeled at a speed of 300 mm / min using a tensile tester (manufactured by A & D Co., Ltd.). The state was evaluated according to the following criteria.
○: A strong adhesion between the polyester film and the multilayer film was confirmed by maintaining a sufficient laminate strength.
X: Confirmed easy peeling between the polyester film and the multilayer film due to insufficient laminating strength.

  As is apparent from the above table, the antifogging multilayer film of the present invention has suitable antifogging properties and laminate strength while realizing good film forming properties. On the other hand, the multilayer films of Comparative Examples 1 to 5 did not have suitable antifogging properties. Moreover, the multilayer film of Comparative Example 6 was not able to obtain good discharge stability.

Claims (10)

Laminate layer (A) containing polypropylene resin (a) and containing no antifogging agent, intermediate layer (B1) containing linear polyethylene (b11) and antifogging agent (b12), and linear An antifogging multilayer film in which a heat seal layer (C) containing polyethylene (c11) and an antifogging agent (c12) is laminated in the order of (A) / (B1) / (C). The antifogging multilayer film according to claim 1, wherein the total mass of the antifogging agents (b12) and (c12) is 0.2 to 1.0 mass% with respect to the total mass of the multilayer film. Furthermore, it has an intermediate | middle layer (B2) containing linear polyethylene (b2), and is laminated | stacked in order of (A) / (B2) / (B1) / (C). Anti-fogging multilayer film. The anti-fogging multilayer film according to any one of claims 1 to 3, wherein the entire multilayer film has a thickness of 20 to 100 µm. 5. The antifogging multilayer film according to claim 1, wherein a ratio of the thickness of the heat seal layer (C) to the entire thickness of the multilayer film is 5 to 30%. The antifogging multilayer film according to any one of claims 1 to 5, wherein a ratio of the thickness of the laminate layer (A) to the thickness of the entire multilayer film is 10 to 60%. The antifogging multilayer film according to any one of claims 1 to 6, wherein the antifogging agents (b12) and (c12) are nonionic surfactants. A laminate comprising the laminate layer (A) of the antifogging multilayer film according to any one of claims 1 to 7 and a thermoplastic resin film. A packaging material using the laminate according to claim 8. The packaging material according to claim 9, which is a lid for a food packaging container.