WO2015046131A1

WO2015046131A1 - Antifogging multilayer film, laminate using same, and packaging material

Info

Publication number: WO2015046131A1
Application number: PCT/JP2014/075041
Authority: WO
Inventors: 智久木田; 森谷　貴史; 古根村　陽之介
Original assignee: Dic株式会社
Priority date: 2013-09-27
Filing date: 2014-09-22
Publication date: 2015-04-02
Also published as: JPWO2015046131A1; KR102161562B1; JP5962864B2; CN105579231B; TW201515836A; KR20160061308A; CN105579231A; TWI639508B

Abstract

　The present invention relates to a multilayer film obtained by laminating in the order (A)/(B)/(C): a laminate layer (A) having a straight-chain polyethylene (a) as a main component and not including an antifogging agent; an intermediate layer (B) containing a straight-chain polyethylene (b1) and an antifogging agent (b2); and a heat seal layer (C) containing a polypropylene resin (c1) and an antifogging agent (c2), the total mass of the antifogging agent (b2) and the antifogging agent (c2) in relation to the total mass of the multilayer film being within the range of 0.8-1.6 mass percent, both outer surfaces of the multilayer film being treated to have a wet tensile strength within the range of 35-45 mN/m, and the total thickness of the multilayer film being 20-100 µm.

Description

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

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

In recent years, in the food packaging market, for example, in order to increase the visibility of contents such as fruits and vegetables, packaging materials are required to have antifogging properties. This is because the contents inside the packaging material become cloudy due to the transpiration of moisture from the fruits and vegetables in the container, making it difficult to see the contents and reducing the value of the product, that is, the consumer's request for food safety and security This is because it becomes impossible to meet the requirements. Furthermore, while it is essential for the container lid to have a certain sealing property until the contents are taken out, the socially vulnerable (elderly, infants, people with disabilities, etc.) in the trend toward universal design As a consideration to this, a method that is easy for consumers to open, for example, easy opening, is being emphasized.

Currently, as a method for imparting antifogging properties to a packaging material, a method in which an antifogging agent is kneaded into a resin used for the packaging material, molded into a film, and then secondary molded for various packaging materials (for example, Patent Document 1) and a method of applying an antifogging agent to at least the surface in contact with the contents after molding the resin into a film (for example, see Patent Document 2) are known.

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 (see, for example, Patent Document 3), but since the antifogging agent has a property of easily moving in the multilayer film, There is a problem that the antifogging effect is not constant and the effect is not sustainable.

In addition, the method of applying a coating liquid containing an antifogging agent to the film surface requires a drying process of the coating film, resulting in low production efficiency, and further, the antifogging agent on the coated surface flows due to the evaporation of moisture from the contents. As a result, there is a problem that the anti-fogging effect persists.

Japanese Patent Laid-Open No. 04-047936 JP 09-248880 A JP 2007-253349 A

In view of the above circumstances, the problem of the present invention is that the anti-fogging property to prevent fogging from water vapor from the contents is good and has an easy openability, and is suitable for applications such as lids for packaging containers. The object is to provide a film, a laminate formed by laminating the multilayer film on a base film, and a packaging material using the laminate.

As a result of earnest research to solve such problems, the present inventor has selected at least three layers of multilayer films formed by laminating specific olefin-based resins, and selects a layer for kneading an antifogging agent. The present inventors have found that a multilayer film obtained by appropriately adjusting the use ratio of the agent and appropriately performing the surface treatment of the multilayer film can solve the above-mentioned problems, and completed the present invention.

That is, the present invention comprises a laminate layer (A) containing linear polyethylene (a) as a main component and containing no antifogging agent, and an intermediate layer containing linear polyethylene (b1) and antifogging agent (b2). A multilayer in which (B) and a heat seal layer (C) containing a polypropylene resin (c1) and an antifogging agent (c2) are laminated in the order of (A) / (B) / (C). A total mass of the antifogging agent (b2) and the antifogging agent (c2) is included in the range of 0.8 to 1.6% by mass with respect to the total mass of the multilayer film. And both outer surfaces of the multilayer film are processed in a range of wet tension of 35 to 45 mN / m, and the total thickness of the multilayer film is 20 to 100 μm, And a laminate comprising a base material film and a packaging material using the same It is intended to provide.

The anti-fogging multilayer film of the present invention and a laminate using the same exhibit easy-opening properties based on delamination when heat-sealed as a lid for packaging containers or when sheet-formed and sheet-sealed To do. Furthermore, since it has good antifogging properties and has durability, it can be suitably used as a packaging material for fruits and vegetables.

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 is mainly composed of linear polyethylene (a), and the layer does not contain an antifogging agent.

In the present invention, the main component means that a specific resin is contained in an amount of 65% by mass or more, preferably 80% by mass or more based on the total amount of resin components forming the layer.

As the linear polyethylene (a), an ethylene monomer as a main component and a co-monomer as butene-1, hexene-1, octene-1, 4- by a low-pressure radical polymerization method using a single site catalyst. Copolymerized with α-olefin such as methylpentene. The comonomer content is preferably in the range of 0.5 to 20 mol%, and more preferably in the range of 1 to 18 mol%.

Examples of the single site catalyst include various single site catalysts such as a metallocene catalyst system such as a combination of a metallocene compound of Group IV or V transition metal of the periodic table and an organoaluminum compound and / or an ionic compound. 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 adhesive strength between resin layers can be obtained.

It The density of the linear polyethylene (a) used in the laminate layer (A), preferably from 0.920 ~ 0.945g / cm ^3, in the range of 0.930 ~ 0.940g / cm ³ Is more preferable. If the density is within this range, it has appropriate rigidity, excellent mechanical strength such as pinhole resistance, and film film formability and extrusion suitability are improved. The melting point is preferably in the range of 60 to 130 ° C, more preferably 70 to 125 ° C. If melting | fusing point is this range, processability at the time of co-extrusion processing with a process stability and another layer will improve. The MFR (190 ° C., 21.18N) of the linear polyethylene (a) is preferably 2 to 20 g / 10 minutes, and more preferably 3 to 10 g / 10 minutes. When the MFR is within this range, the extrusion moldability of the film is improved.

As described above, the laminate layer (A) is mainly composed of the linear polyethylene (a), but when laminating with another base material and an adhesive, or when printing is performed. In addition, other resins may be used in combination from the viewpoint of improving the adhesion with an adhesive or printing ink. Other resins that can be used at this time are preferably ethylene resins from the viewpoint of the transparency of the resulting multilayer film. For example, 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) and ethylene-methacrylic acid copolymer (EMAA); further, ionomers of ethylene-acrylic acid copolymers and ionomers of ethylene-methacrylic acid copolymers Etc., and a module having a cyclic olefin structure such as a norbornene monomer. Mentioned copolymers of mer and ethylene and the like, alone, may be used by mixing two or more kinds.

[Intermediate layer (B)]
The intermediate layer (B) in the multilayer film of the present invention contains linear polyethylene (b1) and an antifogging agent (b2). This linear polyethylene (b1) is the same as the linear polyethylene (a) used for the laminate layer (A) described above.

As a use ratio of the linear polyethylene (b1) in the intermediate layer (B), the resin is preferably the main component, and particularly preferably 90% by mass or more. Other resin types that can be used in combination are the same as those exemplified as the resin that can be used together in the laminate layer (A).

The antifogging agent (b2) 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 dimethylolpropane monostearate; diethanolalkylamine and diethanolalkylamide surfactants such as lauryl diethanolamine, oleyl diethanolamine, stearyl diethanolamine, lauryl diethanolamide, oleyl diethanolamide, stearyl diethanolamide And 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 proportion of the antifogging agent (b2) used in the intermediate layer (B) is preferably in the range of 0.8 to 5.0% by mass, particularly 1.0 to 5.0%, based on 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).

The intermediate layer (B) in the anti-fogging multilayer film of the present invention may have a multilayer structure of two or more layers comprising a plurality of linear polyethylenes having different densities. From the viewpoint of effectively suppressing migration, the intermediate layer (B) in the anti-fogging multilayer film is formed from layers (B1) and (B2) having different densities, and (A) / (B1) The density of the linear polyethylene laminated in the order of / (B2) / (C) and contained in the layer (B1) is higher than the density of the linear polyethylene contained in the layer (B2). Preferably it is formed.

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 0.920 to 0.945 g / cm ³ , and the layer (B2) The density of the linear polyethylene contained in the range of 0.880 to 0.920 g / cm ³ balances the antifogging property as a multilayer film and the suppression of the migration of the antifogging agent to the laminate layer. It is preferable from an excellent point. Except for the density condition of the linear polyethylene, the linear polyethylene (b1) and the antifogging agent (b2) used for the intermediate layer (B) are the same.

In particular, the density of the linear polyethylene used for the intermediate layer (B1) adjacent to the laminate layer (A) is the same as or smaller than the density of the linear polyethylene (a) used for the laminate layer (A). From the viewpoint of suppressing the migration of the antifogging agent (b2).

The proportion of the antifogging agent (b2) used may be the same or different in all the plurality of intermediate layers (B), and the type of the antifogging agent (b2) to be used is the same. Although it may be present or different, it is preferable to use the same kind of antifogging agent from the viewpoint of sustainability of the antifogging property as a film.

[Heat seal layer (C)]
As the heat seal layer (C) in the multilayer film of the present invention, a polypropylene resin (c1) is used from the viewpoint of facilitating the expression of easy opening when used as a container lid or packaging bag. Is essential.

The polypropylene resin (c1) is not particularly limited as long as it can be laminated with the above-mentioned laminate layer (A) and intermediate layer (B), and propylene homopolymer, propylene / α-olefin random copolymer. Examples of the polymer include propylene-ethylene copolymer, propylene-butene-1 copolymer, propylene-ethylene-butene-1 copolymer, and metallocene catalyst-based polypropylene. These may be used alone or in combination. Desirable is a propylene-α-olefin random copolymer, and a propylene / α-olefin random copolymer polymerized using a metallocene catalyst as described above is particularly preferable. By using these propylene-based resins as the resin for the heat seal layer (C), the sealing surface of the packaging container can be suitably used as a lid for a packaging container in which the sealing layer is a resin layer containing a polypropylene-based resin.

The polypropylene resin (c1) preferably has an MFR (230 ° C.) of 0.5 to 30.0 g / 10 min 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 min. If MFR and melting | fusing point are this range, there will be little shrinkage | contraction of the film at the time of heat sealing, and also the film-forming property of a film will improve.

The proportion of the polypropylene resin (c1) used in the heat seal layer (C) is preferably based on the resin, and more preferably 90% by mass or more. Other resin types that can be used in combination are the same as those exemplified as the resin that can be used together in the laminate layer (A).

As the antifogging agent (c2) used for the heat seal layer (C), any of those exemplified as the antifogging agent (b2) used for the intermediate layer (B) can be used, and suitable ones are also the same. .

The antifogging agent (b2) used for the intermediate layer (B) and the antifogging agent (c2) used for the heat seal layer (C) may be the same or different. When using a masterbatch antifogging agent, from the viewpoint of compatibility, the base resin may be a polyethylene resin in the intermediate layer (B) and a polypropylene resin in the heat seal layer (C), respectively. preferable.

The proportion of the antifogging agent (c2) used in the heat seal layer (C) is preferably in the range of 1.0 to 6.0% by mass, particularly 1.2 to 4%, based on the total mass of the layer. The range is preferably 0.0 mass%. By using the antifogging agent (c2) within this range, it becomes easy to obtain a film having good antifogging properties and antifogging durability as a film.

[Anti-fogging multilayer film]
The antifogging multilayer film of the present invention is a multilayer film in which the laminate layer (A), the intermediate layer (B), and the heat seal layer (C) are laminated at (A) / (B) / (C). is there. The anti-fogging multilayer film of the present invention does not contain an anti-fogging agent in the laminate layer (A) and contains an anti-fogging agent in both the intermediate layer (B) and the heat seal layer (C). Furthermore, the content of the antifogging agent is such that the total mass of the antifogging agent is 0.8 to 1.6% by mass with respect to the total mass of the multilayer film, and the wetting tension on both outer surfaces is 35 to 45 mN / m. The total thickness is 20 to 100 μm. The multilayer film having the structure can realize suitable antifogging properties, can realize suitable adhesive strength when heat-sealed, and can maintain suitable easy-openability between (B) / (C) layers even when opened. . In addition, the antifogging agent does not easily fall off, and the antifogging property can be stably maintained, and the printing and adhesion to other substrates can be improved.

The total thickness of the antifogging multilayer film of the present invention is in the range of 20 to 100 μm because it is easy to laminate when it is used by being laminated with another substrate, and suitable antifogging properties can be obtained. In particular, the range of 30 to 80 μm is preferable from the viewpoint of easy film formation.

The ratio of each layer in the multilayer film is such that the thickness ratio of the intermediate layer (B) is in the range of 35 to 60% from the viewpoint of sealing properties, easy opening properties, and laminating properties, and the heat sealing layer (C) The thickness ratio is preferably in the range of 8 to 15%.

The total amount of the antifogging agent contained in the entire antifogging multilayer film of the present invention is 0.8 to 1.6% by mass, particularly 1.0 to 1.3% by mass. It is preferable from the viewpoints of good film properties, antifogging properties, and antifogging durability.

For each layer (A), (B), (C) of the antifogging multilayer film of the present invention, an antistatic agent, a thermal stabilizer, a nucleating agent, an antioxidant, a lubricant, an antiblocking agent, and a release agent. In addition, components such as an ultraviolet absorber and a colorant can be added as long as the object of the present invention is not impaired. 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.

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 the corona discharge treatment is not particularly limited. For example, each of JP-B-39-12838, JP-A-47-19824, JP-A-48-28067, 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 .

The peel strength after heat sealing of the laminated film of the present invention may be appropriately adjusted according to the use mode. For example, the laminated film of the present invention cut into 10 cm × 5 cm is applied to a polypropylene sheet at 180 ° C., 0 ° C. The peel strength when heat sealed at 2 MPa for 1 second is preferably 5 to 20 N / 15 mm, and more preferably 8 to 12 N / 15 mm. By setting it as the said peeling strength, peeling and dropping of a laminated film do not occur easily, and the easy opening property at the time of opening becomes especially suitable.

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 (B), and a heat seal layer (C) is each separately. (A) / (B) / (C) or (A) / (B1) / (B2) / () 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. Among them, the T-die / chill roll method is easy to suppress deterioration of the film appearance and to form a uniform layer structure when coextruding resins having different melting points and Tg, and to easily obtain a film with suitable transparency and gloss. Therefore, it is preferable. The inflation method is preferable because the equipment is simple, and is suitable for the production of a small variety of products.

The antifogging multilayer film of the present invention can be obtained as a substantially unstretched multilayer film by the above-described production method, so that 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 other base materials. 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. Blends with tackifiers such as esters, terpene / phenol copolymers, terpene / indene copolymers, or 2-ethylhexyl acrylate / n-butyl acrylate copolymer, 2-ethylhexyl acrylate / ethyl acrylate / 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, with an organic solvent can be used.

The use of the laminate of the present invention is not particularly limited, but it can be suitably used as a lid for packaging containers used for foods, medicines, industrial parts, miscellaneous goods, magazines, and the like. In particular, it is preferable that the outermost layer of the packaging container (the part that adheres to the heat seal layer of the multilayer film of the present invention) contains various propylene resins from the viewpoint of the balance between easy-openability and seal 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.

(Preparation Example 1)
[Preparation of antifogging agent masterbatch based on propylene-ethylene copolymer]
Propylene-ethylene copolymer [MFR (230 ° C.) 7 g / 10 min, melting point 130 ° C. (hereinafter referred to as polypropylene (1))] and nonionic surfactant Riquemar O-71-D manufactured by Riken Vitamin Co., Ltd. After mixing so as to have a mass ratio of 90/10 and melt-kneading with an extruder, an antifogging agent master batch pellet was obtained with a granulator. (Hereinafter referred to as antifogging agent (1))

(Preparation Example 2)
[Preparation of antifogging agent masterbatch based on linear polyethylene]
Linear polyethylene [MFR (190 ° C.) 4 g / 10 min, density 0.905 g / cm ³ ] [hereinafter referred to as LLDPE (1)] and nonionic surfactant Riquemar O-71-D manufactured by Riken Vitamin Co., Ltd. Were mixed so as to have a mass ratio of 80/20, melt-kneaded with an extruder, and antifogging agent master batch pellets were obtained with a granulator. (Hereinafter referred to as anti-fogging agent (2))

(Preparation Example 3)
[Preparation of anti-fogging agent master batch based on low density polyethylene]
A low density polyethylene (hereinafter referred to as LDPE) having a density of 0.918 g / cm ³ and MFR of 3.4 g / 10 min and a nonionic surfactant Riquemar O-71-D manufactured by Riken Vitamin Co., Ltd. has a mass ratio of 80/20. The mixture was melted and kneaded with an extruder, and antifogging agent master batch pellets were obtained with a granulator. (Hereinafter referred to as anti-fogging agent (3))

Example 1
As a resin for the heat seal layer (C), 76 parts of polypropylene (1) and 24 parts of an antifogging agent (1) were mixed and used. The antifogging agent concentration of the heat seal layer (C) at this time was 2.4% by mass. As the resin for the intermediate layer (B2), 80 parts of LLDPE (1) and 20 parts of antifogging agent (2) were mixed and used. The antifogging agent concentration at this time was 4% by mass. As the resin for the intermediate layer (B1), 97.5 parts of linear polyethylene (hereinafter referred to as LLDPE (2)) having a density of 0.933 g / cm ³ and MFR of 5.0 g / 10 min and an antifogging agent (2) 2.5 The parts were mixed and used. The antifogging agent concentration at this time was 0.5%. LLDPE (2) was used as the resin for the laminate layer (A). 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) / (B1) / (B2) / (C) is 10 μm / 12 μm / 4 μm from the T die at an extrusion temperature of 250 ° C. by coextrusion method. It extruded so that it might become / 4 micrometer, and it cooled with the 40 degreeC water cooling metal cooling roll. Next, corona discharge treatment was performed on both sides of the laminate layer and the heat seal layer, wound on a roll, and aged in a aging room at 38 ° C. for 24 hours to obtain a multilayer film of the present invention having a total thickness of 30 μm. At this time, the antifogging agent concentration with respect to the mass of the entire film is about 1.1% by mass. The wetting tension on the surface of the laminate layer was 39 mN / m, and the wetting tension on the surface of the heat seal layer was 44 mN / m. Thereafter, the obtained coextruded film and 12 μm of the biaxially stretched polyester film were bonded together with a polyurethane-based adhesive [Dick Dry LX510 / KR90 manufactured by DIC Corporation] to obtain a laminate.

(Example 2)
As the resin for the intermediate layer (B1), LLDPE (2) and antifogging agent (2) were mixed and used so as to have a mixing ratio of 99.5 / 0.5. The antifogging agent concentration in the intermediate layer (B1) at this time was 0.1% by mass (the antifogging agent concentration of the entire film was about 0.9% by mass). Further, the corona discharge output on the heat seal layer side was adjusted so that the wetting tension on the surface of the heat seal layer was 39 mN / m. Except for these, the laminate of Example 2 was obtained in the same manner as Example 1.

Example 3
As the resin for the intermediate layer (B1), LLDPE (2) and antifogging agent (2) were mixed and used so that the mass ratio was 99.5 / 0.5. The antifogging agent concentration in the intermediate layer (B1) at this time was 0.1% by mass (the antifogging agent concentration of the entire film was about 0.9% by mass). Further, the corona discharge output on the heat seal layer side was adjusted so that the wetting tension on the surface of the heat seal layer was 35 mN / m. Except for these, the laminate of Example 3 was obtained in the same manner as Example 1.

Example 4
Adjust the take-up speed by changing the rotation speed of the cooling roll so that the total thickness is 90 μm and the thickness of each layer of (A) / (B1) / (B2) / (C) is 30 μm / 36 μm / 12 μm / 12 μm A laminated body of Example 4 was obtained in the same manner as Example 1 except that.

(Example 5)
As the resin for the intermediate layer (B1), LLDPE (2) and antifogging agent (2) were mixed and used so that the mass ratio was 92/8. The antifogging agent concentration in the intermediate layer (B1) at this time was 1.6% by mass (the antifogging agent concentration of the entire film was about 1.5% by mass). Other than that was carried out similarly to Example 1, and obtained the laminated body of Example 5. FIG.

(Example 6)
A laminate of Example 6 was obtained in the same manner as in Example 1 except that LLDPE (2) was used instead of LLDPE (1) as the resin for the intermediate layer (B2).

(Example 7)
Example 1 except that linear polyethylene (hereinafter referred to as LLDPE (3)) having a density of 0.920 g / cm ³ and MFR (190 ° C.) of 4 g / 10 min was used as the resin for the laminate layer (A). Similarly, the laminate of Example 7 was obtained.

(Example 8)
As the resin for the heat seal layer (C), polypropylene (1) and antifogging agent (1) were mixed and used so that the mass ratio was 76/24. The antifogging agent concentration in the heat seal layer (C) at this time was 2.4% by mass. As the resin for the intermediate layer (B1), LLDPE (1) and antifogging agent (2) were mixed and used so that the mass ratio was 92.5 / 7.5. The antifogging agent concentration in the intermediate layer (B1) at this time was 1.5% by mass. LLDPE (2) was used as the resin for the laminate layer (A). Resin is supplied to each of the heat seal layer (C) extruder (diameter 30 mm), the intermediate layer (B1) extruder (diameter 40 mm) and the laminate layer (A) extruder (diameter 30 mm), and co-extrusion Example 3 was carried out in the same manner as in Example 3 except that the extrusion temperature was 250 ° C. and extrusion was performed from the T die so that the thickness of each layer (A) / (B1) / (C) was 10 μm / 16 μm / 4 μm. 8 laminates were obtained. At this time, the antifogging agent concentration of the whole film was about 1.1% by mass.

Example 9
A laminate of Example 9 was obtained in the same manner as Example 8 except that LLDPE (2) was used instead of LLDPE (1) as the resin for the intermediate layer (B1).

(Example 10)
As a resin for the heat seal layer (C), a propylene-ethylene-1-butene copolymer [MFR (230 ° C.) 7 g / 10 min, melting point 129 ° C. (hereinafter referred to as polypropylene (2))] and an antifogging agent ( 1) was mixed and used so that the mass ratio was 76/24. Further, the corona discharge output on the heat seal layer side was adjusted so that the wetting tension on the surface of the heat seal layer was 39 mN / m. Except for these, the laminate of Example 10 was obtained in the same manner as Example 1.

(Example 11)
Except for adjusting the corona discharge output on the laminate layer side so that the wetting tension on the laminate surface is 44 mN / m and adjusting the corona treatment output on the heat seal layer side so that the wetting tension on the heat seal surface is 39 mN / m. In the same manner as in Example 1, the laminate of Example 11 was obtained.

Example 12
A laminate of Example 12 was obtained in the same manner as Example 11 except that the corona discharge output on the laminate layer side was adjusted so that the wetting tension on the laminate surface was 36 mN / m.

(Example 13)
As a resin for the laminate layer (A), LLDPE (2) and LDPE are mixed so that the mass ratio is 80/20, and the corona treatment output on the heat seal layer side is also adjusted to wet the heat seal surface. A laminate of Example 13 was obtained in the same manner as Example 1 except that the tension was 39 mN / m.

(Example 14)
As the resin for the intermediate layer (B1), LLDPE (2), LDPE and antifogging agent (2) were mixed and used so that the mass ratio was 77.5 / 20 / 2.5. The antifogging agent concentration in the intermediate layer (B1) at that time was 0.5% by mass. As the resin for the intermediate layer (B2), LLDPE (1), LDPE and antifogging agent (2) were mixed and used so that the mass ratio was 60/20/20. The antifogging agent concentration at that time was 4%. Moreover, the laminated body of Example 14 was obtained in the same manner as Example 1 except that the corona treatment output on the heat seal layer side was also adjusted and the wetting tension of the heat seal surface was 39 mN / m. At this time, the antifogging agent concentration of the whole film was about 1.1% by mass.

(Comparative Example 1)
A laminate of Comparative Example 1 was obtained in the same manner as Example 1 except that the heat seal layer was not subjected to corona discharge treatment.

(Comparative Example 2)
A laminate of Comparative Example 2 was obtained in the same manner as in Example 1 except that the corona discharge output on the heat seal layer side was adjusted so that the wetting tension on the surface of the heat seal layer was 33 mN / m.

(Comparative Example 3)
The heat seal layer is not subjected to corona discharge treatment, the total thickness is 150 μm, and the thickness of each layer of (A) / (B1) / (B2) / (C) is 50 μm / 60 μm / 20 μm / 20 μm A laminate of Comparative Example 1 was obtained in the same manner as in Example 1 except that the rotation speed of the cooling roll was changed and the take-up speed was adjusted.

(Comparative Example 4)
The corona discharge output on the heat seal layer side was adjusted so that the wetting tension on the surface of the heat seal layer was 39 mN / m. As the resin for the intermediate layer (B1), only LLDPE (2) is used, no antifogging agent is added, and the resin for the intermediate layer (B2) has a mass ratio of LLDPE (1) and antifogging agent (2). It mixed and used so that it might become 90/10. The antifogging agent concentration in the intermediate layer (B2) at this time was 2.0% by mass. A laminated body of Comparative Example 4 was obtained in the same manner as Example 1 except for these. At this time, the antifogging agent concentration of the entire film was about 0.6% by mass.

(Comparative Example 5)
As the resin for the intermediate layer (B1), LLDPE (2) and antifogging agent (2) were mixed and used so that the mass ratio was 88/12. The antifogging agent concentration at this time was 2.4% by mass in the intermediate layer (B1). A laminated body of Comparative Example 5 was obtained in the same manner as Example 1 except for these. At this time, the antifogging agent concentration of the entire film was about 1.8% by mass.

(Comparative Example 6)
As a resin for the laminate layer (A), LDPE and antifogging agent (2) were mixed and used so that the mass ratio was 99/1. The antifogging agent concentration in the laminate layer (A) at this time was 0.2% by mass. As the resins for the intermediate layers (B1) and (B2), LDPE and antifogging agent (2) were mixed and used so that the mass ratio was 98.5 / 1.5. The antifogging agent concentration in the intermediate layers (B1) and (B2) at this time was 0.3% by mass. A laminated body of Comparative Example 6 was obtained in the same manner as Example 1 except for these. At this time, the antifogging agent concentration of the entire film was about 1.0% by mass.

(Comparative Example 7)
A laminate of Comparative Example 7 was obtained in the same manner as in Example 1 except that only LDPE (branched) was used as the resin for the laminate layer (A).

(Comparative Example 8)
As the resin for the laminate layer (A), LLDPE (2) and antifogging agent (2) were mixed and used so that the mass ratio was 99/1. The amount of the antifogging agent in the intermediate layer (B1) at this time was 0.2% by mass. Except this, it carried out similarly to Example 1, and obtained the laminated body of the comparative example 8. At this time, the antifogging agent concentration of the whole film was about 1.1% by mass.

(Comparative Example 9)
As the resin for the intermediate layer (B1), LDPE and the antifogging agent (3) were mixed and used so that the mass ratio was 92.5 / 7.5. The antifogging agent concentration in the intermediate layer (B1) at this time was 1.5% by mass. The laminate of Comparative Example 9 was obtained in the same manner as in Example 8, except that the corona treatment output on the heat seal layer side was also adjusted and the wetting tension on the heat seal surface was set to 44 mN / m. At this time, the antifogging agent concentration of the whole film was about 1.1% by mass.

(Comparative Example 10)
As the resin for the intermediate layer (B1), LDPE and antifogging agent (3) were mixed and used so that the mass ratio was 97.5 / 2.5. The antifogging agent concentration in the intermediate layer (B1) at this time was 0.5% by mass. Further, as the resin for the intermediate layer (B2), LDPE and antifogging agent (3) were mixed and used so that the mass ratio was 80/20. The antifogging agent concentration at that time was 4% by mass. Except these, it carried out similarly to Example 1, and obtained the laminated body of the comparative example 10. At this time, the antifogging agent concentration of the whole film was about 1.1% by mass.

(Comparative Example 11)
A laminate of Comparative Example 11 was obtained in the same manner as Example 1 except that the laminate layer side was not subjected to corona discharge treatment.

(Comparative Example 12)
As the resin for the intermediate layer (B1), LLDPE (2) and antifogging agent (2) were mixed and used so that the mass ratio was 95/5. The antifogging agent concentration in the intermediate layer (B1) at this time was 1% by mass. Moreover, LLDPE (1) and antifogging agent (2) were mixed and used so that it might become 75/26 mass ratio as resin for intermediate | middle layers (B2). At that time, the antifogging agent concentration in the intermediate layer (B2) was 5%. No antifogging agent was added to the laminate layer (A) and the heat seal layer (C). Except these, it carried out similarly to Example 1, and obtained the laminated body of the comparative example 12. At this time, the antifogging agent concentration of the whole film was about 1.1% by mass.

(Comparative Example 13)
LLDPE (2) is used as the resin for the laminate layer (A), LLDPE (2) is used as the resin for the intermediate layer (B1), and LLDPE (1) is used as the resin for the intermediate layer (B2). Without adding the clouding agent, polypropylene (1) and the antifogging agent (1) were mixed and used as a resin for the heat seal layer (C) so that the mass ratio was 20/80. At this time, the antifogging agent concentration of the whole film was about 1.1% by mass. They were introduced into each extruder and extruded at 250 ° C. in the same manner as in Example 1. However, a poor appearance due to remarkable surface roughness occurred and a good film could not be obtained.

The following evaluation was performed on the laminated films obtained in the above examples and comparative examples. The obtained results are shown in the table. In addition, content of the compounding component of each layer in a table | surface is the mass ratio in a layer.

[Evaluation of film appearance after aging]
By the coextrusion method, the appearance of the sample aged at 38 ° C. for 24 hours of the film extruded from the T-die was visually confirmed.
○: No whitening due to anti-fogging agent bleed is observed ×: Whitening due to anti-fogging agent bleed deteriorates transparency of film

[Evaluation of laminate strength]
Regarding the behavior of the laminate strength between the polyester film and the film obtained by the coextrusion method, the state when peeled at a speed of 300 mm / min using a tensile tester (manufactured by A & D Co., Ltd.) is as follows. Evaluated by criteria.
○: Strong adhesion between the polyester film and the film obtained by the co-extrusion method was confirmed by maintaining sufficient laminate strength.
X: Easy peeling between the polyester film and the film obtained by the co-extrusion method was confirmed due to insufficient laminating strength.

[Anti-fogging effect confirmation test]
The obtained laminate was aged for 24 hours in a 38 ° C. environment, then cut into 8 cm × 8 cm, and heat-sealed with a 71φ injection container (manufactured by Toko) containing 30 ml of 40 ° C. water (pressure) 64 kgf / cup, temperature 160 ° C., time 1.0 second), and stored visually at 3 ° C. for 3 hours in the low temperature room using the following criteria to confirm the antifogging effect.
○: A continuous water film is formed on the film surface and visibility is good. △: Fine water droplet adhesion is good visibility on the film surface. ×: Water droplet adhesion is present and visibility is deteriorated.

[Heat seal test]
The obtained laminate was cut out into 10 cm × 5 cm, and was laminated with a polypropylene sheet having a thickness of 0.3 mm so that the heat seal surface was on the polypropylene sheet side, and a heat seal tester (precision heat sealer manufactured by Tester Sangyo). Was set so that the upper heat seal bar adjusted to a predetermined temperature was on the outermost layer side of the laminate, and heat sealed under the condition of 0.2 MPa for 1 second.

[Evaluation of peel strength]
A strip-shaped sample 15 mm wide is cut out in a direction perpendicular to the heat-sealed portion, and the maximum strength when peeled at a speed of 300 mm / min is peeled off using a tensile tester (manufactured by A & D Co., Ltd.). Strength.

As is clear from the above table, the antifogging laminated films of the present invention of Examples 1 to 12 were able to realize suitable antifogging properties and peel strength. Moreover, it had a suitable film appearance and a laminate strength was also suitable. On the other hand, the laminated films of Comparative Examples 1 to 6 and 9 to 11 could not achieve both suitable antifogging properties and peel strength. In addition, the laminated films of Comparative Examples 7 to 8 and 12 to 13 were inferior to the characteristics of the laminated film itself, and were difficult to use practically.

Claims

Laminate layer (A) containing linear polyethylene (a) as a main component and containing no antifogging agent, intermediate layer (B) containing linear polyethylene (b1) and antifogging agent (b2), and polypropylene A heat seal layer (C) containing a resin (c1) and an antifogging agent (c2) is a multilayer film laminated in the order of (A) / (B) / (C),
The total mass of the antifogging agent (b2) and the antifogging agent (c2) is included in the range of 0.8 to 1.6% by mass with respect to the total mass of the multilayer film, and the multilayer film The anti-fogging multilayer film is characterized in that the wet tension of both outer surfaces is in the range of 35 to 45 mN / m and the total thickness of the multilayer film is 20 to 100 μm.
The intermediate layer (B) in the anti-fogging multilayer film is formed from the layer (B1) and the layer (B2) having different densities, and (A) / (B1) / (B2) / (C) The antifogging property according to claim 1, wherein the density of the linear polyethylene laminated in order and contained in the layer (B1) is higher than the density of the linear polyethylene contained in the layer (B2). Multilayer film.
The density of the linear polyethylene contained in the layer (B1) is in the range of 0.920 to 0.945 g / cm 3 , and the density of the linear polyethylene contained in the layer (B2) is 0.880. The antifogging multilayer film according to claim 2, wherein the antifogging multilayer film is in a range of from 0.920 g / cm 3 .
The antifogging multilayer film according to any one of claims 1 to 3, wherein the density of the linear polyethylene (a) is in the range of 0.920 to 0.945 g / cm 3 .
The antifogging 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 thickness ratio of the intermediate layer (B) to the total thickness of the multilayer film is in the range of 35-60%, and the thickness ratio of the heat seal layer (C) is in the range of 8-15%. Any one of anti-fogging multilayer film of Claim 1.
The antifogging multilayer film according to any one of claims 1 to 6, wherein the multilayer film is produced by a coextrusion 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 (c2) are nonionic surfactants.
A laminate comprising the laminate layer (A) of the antifogging multilayer film according to any one of claims 1 to 9 and a thermoplastic resin film.
A packaging material using the laminate according to claim 10.
The packaging material according to claim 11, which is a lid for a food packaging container.
The packaging material according to claim 12, wherein the sealing surface of the food packaging container is a resin layer containing a propylene-based resin.