KR102161562B1 - Antifogging multilayer film, laminate using same, and packaging material - Google Patents

Abstract

The present invention comprises a linear polyethylene (a) as a main component and does not contain an anti-fog agent (A), an intermediate layer (B) containing a linear polyethylene (b1) and an anti-fog agent (b2), and polypropylene A multilayer film formed by laminating a heat seal layer (C) containing a resin (c1) and an antifogging agent (c2) in the order of (A)/(B)/(C), and is antifogging against the total mass of the multilayer film. The total mass of the agent (b2) and the antifogging agent (c2) is contained in the range of 0.8 to 1.6% by mass, and both outer surfaces of the multilayer film are treated in the range of 35 to 45mN/m of wetting tension, and the multilayer film It relates to a multilayer film having a total thickness of 20 to 100 μm.

Description

Antifogging multilayer film, laminate using the same, and packaging material {ANTIFOGGING MULTILAYER FILM, LAMINATE USING SAME, AND PACKAGING MATERIAL}

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

In recent years, in the food package market, for example, in order to increase the visibility of contents such as fruits and vegetables and side dishes, anti-fogging properties are required for packaging materials. This is because if fogging occurs on the inner surface of the packaging due to the evaporation of moisture from fruits and vegetables in the container, it is difficult to see the contents and decrease the product value, that is, it is impossible to comply with the demands of consumers who want food safety and security. It is caused by becoming. In addition, it is essential for the container cover material to have a certain seal until the contents are taken out, but in the trend of universal design, as a consideration for the socially underprivileged (elderly people, infants, disabled people, etc.), consumers A method that is easy to open, for example, openability continues to be important.

Currently, as a method of imparting anti-fog properties to a packaging material, a method of kneading an anti-fogging agent into a resin used for a packaging material, molding it into a film, and then performing secondary molding for various packaging materials (for example, Patent Document 1) and a method of applying an antifogging agent to at least a surface in contact with the contents after molding a resin into a film form (for example, refer to Patent Document 2) is known.

In the method of kneading an antifogging agent into a resin, in the case of a single layer film or when kneading an antifogging agent into the entire layer of a multilayer film, printing is performed on the surface of the antifogging agent, or when bonding with another base film, to the surface. The bleed-out antifogging agent may react with printing ink or adhesive, causing peeling of the printed surface or poor adhesion. In the case of a multilayer film, an example in which an antifogging agent is kneaded and put only in a specific layer is also provided (for example, see Patent Document 3), but since the antifogging agent has a property that is easy to move in the multilayer film, the antifogging effect is not constant. However, there is a problem that the effect has no persistence.

In addition, in the method of applying a coating liquid containing an antifogging agent to the film surface, a drying process of the coating film is required, resulting in low production efficiency, and the antifogging agent on the coated surface flows out due to the evaporation of moisture from the contents, resulting in the persistence of the antifogging effect. There is a problem of deterioration.

Japanese Unexamined Patent Publication No. Hei 04-047936 Japanese Unexamined Patent Publication No. Hei 09-248880 Japanese Unexamined Patent Publication No. 2007-253349

In view of the above circumstances, the subject of the present invention is a multilayer film having good antifogging properties to prevent fogging from the contents, and excellent releasability, and suitable for use as a lid material for packaging containers, It is to provide a laminate formed by laminating this multilayer film on a base film, and a packaging material using the same.

As a result of intensive research to solve these problems, the inventors of the present invention have found that a multilayer film of at least three layers formed by laminating a specific olefin-based resin, wherein the selection of a layer for kneading an antifogging agent, adjusting the use ratio of the antifogging agent, And the multilayer film obtained by appropriately performing the surface treatment of the multilayer film found out that the said subject could be solved, and this invention was completed.

That is, the present invention comprises a linear polyethylene (a) as a main component and does not contain an antifogging agent (A), an intermediate layer (B) containing the linear polyethylene (b1) and an antifogging agent (b2), and A multilayer film obtained by laminating a heat seal layer (C) containing a polypropylene resin (c1) and an antifogging agent (c2) in the order of (A)/(B)/(C), the total mass of the multilayer film 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, and both outer surfaces of the multilayer film are in the range of 35 to 45 mN/m of wetting tension. An anti-fogging multilayer film which has been treated and has a total thickness of 20 to 100 µm, a laminate obtained by laminating this and a base film, and a packaging material using the same.

The anti-fogging multilayer film of the present invention and the laminate using the same exhibit releasability based on interlayer peeling when heat-sealed as a cover material of a packaging container or when formed into a bag and sheet-sealed. In addition, since it has good anti-fogging properties and its persistence, it can be suitably used as a packaging material for fruits and vegetables or side dishes.

Below, the antifogging multilayer film of this invention and each part which comprises the laminated body formed using the same are explained in full detail.

[Laminate layer (A)]

The laminate layer (A) of the present invention is characterized by having a linear polyethylene (a) as a main component, and the layer does not contain an antifogging agent.

In the present invention, to be a main component means to contain a specific resin in an amount of 65% by mass or more, preferably 80% by mass or more with respect to the total amount of the resin component forming the layer.

As the linear polyethylene (a), an ethylene monomer is used as a main component by a low pressure radical polymerization method using a single site catalyst, and as a comonomer, butene-1, hexene-1, octene-1,4-methylpentene, etc. It is a copolymerization of α-olefin of. The content of comonomer is preferably in the range of 0.5 to 20 mol%, 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 a transition metal of Group IV or V of the periodic table and an organoaluminum compound and/or an ionic compound. In addition, since the single-site catalyst has a uniform active point, the molecular weight distribution of the obtained resin becomes sharp compared to a multi-site catalyst having a non-uniform active point, so that the low molecular weight component is less precipitated when formed on a film, and It is preferable because a resin having excellent physical properties can be obtained with excellent stability in adhesive strength.

The density of the linear polyethylene (a) used for the laminate layer (A) is preferably 0.920 to 0.945 g/cm 3, more preferably in the range of 0.930 to 0.940 g/cm 3. When the density is within this range, it has moderate rigidity, is excellent in mechanical strength such as pinhole resistance, and the film-forming property and extrusion suitability are improved. Moreover, it is preferable that it is a range of 60-130 degreeC, and, as for a melting point, 70-125 degreeC is more preferable. When the melting point is in this range, the processing stability and workability in coextrusion processing with other layers are improved. In addition, the MFR (190°C, 21.18N) of the linear polyethylene (a) is preferably 2 to 20 g/10 minutes, 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 using another substrate and an adhesive, or when performing printing, adhesion with the adhesive or printing ink Other resins may be used in combination from the viewpoint of the purpose of improving At this time, as other resins that can be used in combination, an ethylene-based resin is preferable from the viewpoint of transparency of the obtained multilayer film. For example, branched polyethylene, ethylene-vinyl acetate copolymer (EVA), ethylene-methylmethacrylic Rate copolymer (EMMA), ethylene-ethyl acrylate copolymer (EEA), ethylene-methyl acrylate (EMA) copolymer, ethylene-ethyl acrylate-maleic anhydride copolymer (E-EA-MAH), ethylene- Ethylene-based copolymers such as acrylic acid copolymer (EAA) and ethylene-methacrylic acid copolymer (EMAA); In addition, the ionomer of ethylene-acrylic acid copolymer, the ionomer of ethylene-methacrylic acid copolymer, and the like, and copolymers of ethylene and the like with a monomer having a cyclic olefin structure such as a norbornene-based monomer may be mentioned. You may mix and use more than a kind.

[Intermediate layer (B)]

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

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

The anti-fogging agent (b2) is not particularly limited as long as it is generally added to an olefin-based resin to impart anti-fogging properties, and for example, anionic surfactants, nonionic surfactants, cationic surfactants Active agents, amphoteric surfactants and the like can be used, and it is preferable to use a nonionic surfactant.

Specifically, sorbitan monostearate, sorbitan distearate, sorbitan monopalmitate, sorbitan dipalmitate, sorbitan monobehenate, sorbitan dibehenate, sorbitan monolaurate, sorbitan dilau Sorbitan-based surfactants such as rate; Glycerin monolaurate, glycerin dilaurate, diglycerin monopalmitate, diglycerin dipalmitate, glycerin monostearate, glycerin distearate, diglycerin monostearate, diglycerin distearate, diglycerin monolaurate, Glycerin surfactants such as diglycerine dilaurate; Polyethylene glycol-based surfactants such as polyethylene glycol monostearate and polyethylene glycol monopalminate; Trimethylolpropane surfactants such as trimethylolpropane monostearate; Diethanolalkylamine-based and diethanolalkylamide-based surfactants such as lauryldiethanolamine, oleyldiethanolamine, stearyldiethanolamine, lauryldiethanolamide, oleyldiethanolamide, and stearyldiethanolamide; Pentaerythritol surfactants such as pentaerythritol monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan distearate, mono and distearates of sorbitan-diglycerin condensate, etc. have. These can be used alone or in combination of two or more.

The ratio of the antifogging agent (b2) in the intermediate layer (B) to be used is preferably in the range of 0.8 to 5.0% by mass, and 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) within this range, excessive migration to the above-described laminate layer (A) does not occur, and it becomes easy to improve the antifogging property as a film.

The intermediate layer (B) in the antifogging multilayer film of the present invention may be formed of a plurality of linear polyethylenes having different densities, and may have a multilayer structure of two or more layers, and in particular, the migration of the antifogging agent to the laminate layer can be effectively suppressed. From the viewpoint, the intermediate layer (B) in the antifogging multilayer film is formed of a layer (B1) and a layer (B2) having different densities, in the order of (A)/(B1)/(B2)/(C). It is preferable that the density of the linear polyethylene contained in the layer (B1) is higher than that of the linear polyethylene contained in the layer (B2).

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 density of the linear polyethylene contained in the layer (B2) Is preferably in the range of 0.880 to 0.920 g/cm 3 from the viewpoint of excellent balance of antifogging properties as a multilayer film and suppression of migration of the antifogging agent to the laminate layer. Except for the density conditions 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 in 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 in the laminate layer (A). It is preferable from the viewpoint of suppressing the transition of (b2).

The use ratio of the antifogging agent (b2) may be the same or different in all the plurality of intermediate layers (B), and may be the same or different as the kind of the antifogging agent (b2) to be used, but from the viewpoint of the persistence of the antifogging property as a film, It is preferable to use the same kind of antifogging agent.

[Heat room layer (C)]

As the heat seal layer (C) in the multilayer film of the present invention, it is essential to use a polypropylene resin (c1) from the viewpoint of facilitating the expression of releasability in the case of using this as a lid material or packaging bag for a container. It is to do.

The polypropylene resin (c1) is not particularly limited as long as it can be laminated with the laminate layer (A) and the intermediate layer (B) described above, and a propylene homopolymer, a propylene/α-olefin random copolymer, for example A propylene-ethylene copolymer, a propylene-butene-1 copolymer, a propylene-ethylene-butene-1 copolymer, a metallocene catalyst-based polypropylene, etc. are mentioned. Each of these may be used alone or in combination. It is preferably a propylene-?-olefin random copolymer, and as described above, a propylene-?-olefin random copolymer polymerized using a metallocene catalyst is particularly preferred. By using these propylene resins as resins for the heat seal layer (C), in particular, the sealing surface of the packaging container can be suitably used as a cover material for packaging containers in which a resin layer containing a polypropylene resin is used. .

Further, the polypropylene resin (c1) has an MFR (230°C) of 0.5 to 30.0 g/10 minutes, a melting point of 110 to 165°C, and more preferably, MFR (230°C) of 2.0 to It is 15.0 g/10 minutes and the melting point is 115-162 degreeC. When the MFR and the melting point are within this range, shrinkage of the film during heat sealing is small, and the film-forming property of the film is further improved.

As the ratio of use of the polypropylene resin (c1) in the heat chamber layer (C), it is preferable to contain the resin as a 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 resins that can be used in combination 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 in the intermediate layer (B) can be used, and suitable ones are 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 masterbatched antifogging agent, from the viewpoint of compatibility, it is preferable that the base resin is a polyethylene resin for the intermediate layer (B), and a polypropylene resin for the heat seal layer (C).

The ratio of use of the antifogging agent (c2) in the heat seal layer (C) is preferably in the range of 1.0 to 6.0 mass%, and particularly preferably in the range of 1.2 to 4.0 mass% with respect to the total mass of the layer. By using the antifogging agent (c2) in this range, it becomes easy to obtain a film having good antifogging properties and antifogging persistence.

[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 by (A)/(B)/(C). The antifogging multilayer film of the present invention, in the layer structure, does not contain an antifogging agent in the laminate layer (A), contains an antifogging agent in both layers of the intermediate layer (B) and the heat seal layer (C), and The total mass of the antifogging agent with respect to the total mass of the multilayer film is in the range of 0.8 to 1.6 mass%, the wetting tension on both outer surfaces is 35 to 45 mN/m, and the total thickness is 20 to 100 μm. The multilayer film of this configuration can realize suitable antifogging properties, realize suitable adhesive strength when heat-sealed, and maintain suitable releasability between (B)/(C) layers even when opened. I can. In addition, the antifogging agent is less likely to fall off, it is stable, and the antifogging property can be maintained, and the printing and adhesion to other substrates are also improved.

The total thickness of the anti-fogging multilayer film of the present invention is preferably in the range of 20 to 100 µm, particularly 30 to 80 µm, since lamination is easy and suitable anti-fogging properties are obtained when the film is laminated with another substrate and used. It is preferable from the viewpoint of easy film formation.

In addition, as the ratio of each layer in the multilayer film, the thickness ratio of the intermediate layer (B) is in the range of 35 to 60% from the viewpoint of sealability, releasability, and lamination property, and the thickness ratio of the heat seal layer (C) is 8 to It is preferably in the range of 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, and particularly in the range of 1.0 to 1.3% by mass, from the viewpoint of good film formation properties, antifogging properties and antifogging persistence. desirable.

In each of the layers (A), (B), and (C) of the antifogging multilayer film of the present invention, components such as an antistatic agent, a heat stabilizer, a nucleating agent, an antioxidant, a lubricant, an antiblocking agent, a release agent, an ultraviolet absorber, and a colorant It can be added within a range that does not impair the object of the present invention. In particular, in order to impart processing suitability during film forming and packaging suitability of the filling machine, the friction coefficient of the film surface is preferably 1.5 or less, especially 1.0 or less.Therefore, the resin layer corresponding to the surface layer of the multilayer film is provided with a lubricant or anti-blocking agent. It is preferable to add an antistatic agent appropriately.

In addition, in the antifogging multilayer film of the present invention, both outer surfaces of the film are treated, and the surface wetting 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, or surface uneven treatment such as sand blasting, but preferably Is the corona discharge treatment. By performing such a surface treatment, in the case of performing a post-process such as printing or applying an adhesive to the laminate layer (A) of the multilayer film and laminating it with the substrate, the coatability of the ink or the adhesive is improved, and It has excellent adhesion to aluminum and an anchor coating agent, and it becomes easy to avoid problems such as dropping or delamination of ink or deposited aluminum. Further, by treating the surface of the heat seal layer (C), it becomes possible to fix the antifogging agent to the outer surface for a relatively long period of time, resulting in a film having excellent antifogging properties and antifogging persistence. Although the treatment method and treatment degree of the laminate layer (A) and the heat seal layer (C) may be the same or different, from the viewpoint of productivity, it is preferable to treat them by the same method.

The method of the corona discharge treatment is not particularly limited, and for example, Japanese Patent Application No. 39-12838, Japanese Patent Application No. 47-19824, Japanese Patent Application No. 48-28067, Japanese Patent Application No. 52- It can be carried out by a processing method such as described in each publication of No. 42114. As the corona discharge treatment device, a solid state corona treatment device manufactured by Pillar, a LEPEL type surface treatment device, a VETAPHON type treatment device, or the like can be used. Treatment can be performed at atmospheric 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 AC sine wave. The gap clearance between the electrode and the dielectric roll is 0.1 mm to 10 mm, more preferably 1.0 mm to 2.0 mm. Discharge is processed above the dielectric support roller provided in the discharge zone, and the throughput 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 It is 0.38kV·A·min/m².

The peeling strength of the laminated film of the present invention after heat sealing may be appropriately adjusted according to the mode of use. For example, the laminated film of the present invention cut into 10 cm x 5 cm was applied to a polypropylene sheet at 180°C and 0.2. It is preferable that it is 5-20 N/15 mm, and it is more preferable that it is 8-12 N/15 mm of the peeling strength when heat-sealing at MPa for 1 second. By setting it as the said peeling strength, peeling or falling off of a laminated film is hard to generate|occur|produce, and releasability at the time of opening becomes especially suitable.

Although it does not specifically limit as a manufacturing method of the antifogging multilayer film of this invention, For example, each resin or resin mixture used for a laminate layer (A), an intermediate layer (B), and a heat seal layer (C) is separate It is heated and melted with an extruder, and (A)/(B)/(C), or (A)/(B1)/(B2)/(C) in a molten state by a method such as a coextrusion multilayer die method or a feed block method. After lamination in the order of ), a coextrusion method in which a film is formed by inflation or a T-die chill roll method or the like is mentioned. This co-extrusion method is preferable because it is possible to relatively freely adjust the ratio of the thickness of each layer, and a multilayer film having excellent hygiene properties and excellent cost performance can be obtained. Among them, the T-die-chill-roll method is easy to suppress deterioration of the appearance of the film when coextrusion of a resin having a different melting point or Tg, or to form a uniform layer structure, and to obtain a film with suitable transparency or gloss. desirable. In addition, the inflation method is preferable because the equipment is simple, and it is also suitable for the production of small quantities and various kinds.

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

The antifogging multilayer film of the present invention can also be used by bonding with other substrates. The other substrate that can be used at this time is not particularly limited, but from the viewpoint of easily expressing the effects of the present invention, it is preferable to use a thermoplastic resin film having high rigidity and high gloss, particularly a biaxially stretched resin film. Further, in the case of applications that do not require transparency, aluminum foil may be used alone or in combination.

As a stretched resin film, for example, biaxially oriented polyester (PET), biaxially oriented polypropylene (OPP), biaxially oriented polyamide (PA), and ethylene vinyl alcohol copolymer (EVOH) as a central layer coextrusion biaxial Oriented polypropylene, biaxially oriented ethylene vinyl alcohol copolymer (EVOH), and coextruded biaxially oriented 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 as a lamination method, for example, dry lamination, wet lamination, non-solvent lamination, extrusion lamination, etc. There is a method.

Examples of the adhesive used in the dry lamination include polyester-polyurethane adhesive. Moreover, although various pressure-sensitive adhesives may be used, it is preferable to use a pressure-sensitive adhesive. As the pressure-sensitive adhesive, for example, polyisobutylene rubber, butyl rubber, a rubber-based adhesive in which a mixture thereof is dissolved in an organic solvent such as benzene, toluene, xylene, or hexane, or abietic acid rosin in these rubber-based adhesives Mixtures of tackifiers such as esters, terpene/phenol copolymers, terpene/indene copolymers, or 2-ethylhexyl acrylate/n-butyl acrylate copolymer, 2-ethylhexyl acrylate/ethyl acrylate/meth And acrylic pressure-sensitive adhesives obtained by dissolving an acrylic copolymer having a glass transition point of -20°C or lower, such as a methyl acrylate copolymer, with an organic solvent.

The use of the laminate of the present invention is not particularly limited, but it can be suitably used as a cover material for packaging containers used for applications such as food, pharmaceuticals, industrial parts, miscellaneous goods, and magazines. In particular, it is preferable that the outermost layer of the packaging container (a portion that adheres to the heat seal layer of the multilayer film of the present invention) contains various propylene-based resins from the viewpoint of balance between releasability and seal strength.

[Example]

Next, the present invention will be described in more detail with reference to Examples and Comparative Examples. Hereinafter, unless otherwise specified, "parts" are based on mass.

(Preparation Example 1)

[Preparation of a masterbatch of an antifogging agent based on a propylene-ethylene copolymer]

Propylene-ethylene copolymer [MFR (230° C.) 7 g/10 min, melting point 130° C. (hereinafter referred to as polypropylene (1))], and Rikemal O-71-D, a nonionic surfactant manufactured by Rikenvitamin Co., Ltd. Was mixed so that the mass ratio was 90/10, melt-kneaded with an extruder, and then obtained by a granulator to obtain an antifogging agent masterbatch pellet (hereinafter referred to as an antifogging agent (1)).

(Preparation Example 2)

[Preparation of an antifogging agent masterbatch based on linear polyethylene]

Linear polyethylene [MFR (190°C) 4g/10min, density 0.905g/cm3] [hereinafter referred to as LLDPE(1)] and Rikenvitamin Co., Ltd. nonionic surfactant Rikemal O-71-D After mixing so that the mass ratio was 80/20, melt-kneading with an extruder, an antifogging agent masterbatch pellet was obtained with a granulator (hereinafter referred to as an antifogging agent (2)).

(Preparation Example 3)

[Preparation of master batch of antifogging agent based on low density polyethylene]

Mixture of low-density polyethylene [hereinafter referred to as LDPE] with a density of 0.918 g/cm 3 and MFR of 3.4 g/10 min and Likenvitamin Co., Ltd. nonionic surfactant Rikemal O-71-D in a mass ratio of 80/20 Then, after melt-kneading with an extruder, an antifogging agent masterbatch pellet was obtained with a granulator (hereinafter, referred to as an antifogging agent (3)).

(Example 1)

As the resin for the heat seal layer (C), 76 parts of polypropylene (1) and 24 parts of antifogging agent (1) were mixed and used. The concentration of the antifogging agent in the heat seal layer (C) at this time was 2.4% by mass. As a resin for the intermediate layer (B2), 80 parts of LLDPE (1) and 20 parts of antifogging agents (2) were mixed and used. The concentration of the antifogging agent at this time was 4% by mass. As a resin for the intermediate layer (B1), 97.5 parts of linear polyethylene having a density of 0.933 g/cm 3 and MFR of 5.0 g/10 min (hereinafter referred to as LLDPE (2)) and 2.5 parts of an antifogging agent (2) 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). The heat seal layer (C) extruder (diameter 40 mm), the intermediate layer (B2) extruder (diameter 40 mm), the intermediate layer (B1) extruder (diameter 50 mm) and the laminate layer (A) extruder (diameter 50 mm) Resin was supplied to each, and the thickness of each layer of (A)/(B1)/(B2)/(C) was 10 μm/12 μm/4 μm/4 from the T-die at an extrusion temperature of 250° C. by co-extrusion. It extruded so that it might become µm, and cooled with a water-cooled metal cooling roll at 40°C. Subsequently, corona discharge treatment was performed on both sides of the laminate layer and the heat seal layer, wound on a roll, and aged for 24 hours in an aging room at 38°C to obtain a multilayer film of the present invention having a total thickness of 30 μm. At this time, the concentration of the antifogging agent relative 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 coextrusion film and the biaxially stretched polyester film 12 µm were bonded together with a polyurethane adhesive [DICDRY LX510/KR90, manufactured by DIC Corporation] to obtain a laminate.

(Example 2)

As resin for the intermediate layer (B1), LLDPE (2) and antifogging agent (2) were mixed and used so that the mixing ratio was 99.5/0.5. At this time, the concentration of the antifogging agent in the intermediate layer (B1) was 0.1% by mass (the concentration of the entire film was about 0.9% by mass). Further, the corona discharge output on the side of the heat seal layer was adjusted to set the wetting tension on the surface of the heat seal layer to 39 mN/m. Except for these, it carried out similarly to Example 1, and obtained the laminated body of Example 2.

(Example 3)

As 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. At this time, the concentration of the antifogging agent in the intermediate layer (B1) was 0.1% by mass (the concentration of the entire film was about 0.9% by mass). Further, the corona discharge output on the side of the heat seal layer was adjusted to set the wetting tension on the surface of the heat seal layer to 35 mN/m. Except for these, it carried out similarly to Example 1, and obtained the laminated body of Example 3.

(Example 4)

Make the total thickness 90㎛, change the rotation speed of the cooling roll so that the thickness of each layer of (A)/(B1)/(B2)/(C) is 30㎛/36㎛/12㎛/12㎛, and take it out Except having adjusted the speed, it carried out similarly to Example 1, and obtained the laminated body of Example 4.

(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. At this time, the concentration of the antifogging agent in the intermediate layer (B1) was 1.6% by mass (the concentration of the antifogging agent in the entire film was about 1.5% by mass). Other than that, it carried out similarly to Example 1, and obtained the laminated body of Example 5.

(Example 6)

As the resin for the intermediate layer (B2), 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).

(Example 7)

As the resin for the laminate layer (A), it was carried out in the same manner as in 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) 4 g/10 min was used. 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. At this time, the concentration of the antifogging agent in the heat seal layer (C) 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. At this time, the concentration of the antifogging agent in the intermediate layer (B1) was 1.5% by mass. As the resin for the laminate layer (A), LLDPE (2) was used. Resin was 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), respectively, by coextrusion. The laminate of Example 8 was carried out in the same manner as in Example 3 except that the thickness of each layer of (A)/(B1)/(C) was extruded from the T-die at an extrusion temperature of 250°C so that the thickness of each layer became 10 μm/16 μm/4 μm. Got it. At this time, the concentration of the antifogging agent in the entire film was about 1.1% by mass.

(Example 9)

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

(Example 10)

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

(Example 11)

Example 1, except that the corona discharge output on the laminate layer side was adjusted, the wetting tension on the laminate surface was 44 mN/m, and the corona treatment output on the heat seal layer side was also adjusted, and the wetting tension on the heat seal surface was 39 mN/m. In the same manner as in the same manner, a laminate of Example 11 was obtained.

(Example 12)

A laminate of Example 12 was obtained in the same manner as in Example 11, except that the corona discharge output on the laminate layer side was adjusted and the wetting tension of 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, and the wetting tension on the heat seal surface is set to 39 mN/m. Except, it carried out similarly to Example 1, and obtained the laminated body of Example 13.

(Example 14)

As 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. At that time, the concentration of the antifogging agent in the intermediate layer (B1) 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%. In addition, a laminate of Example 14 was obtained in the same manner as in Example 1, except that the corona treatment output on the side of the heat seal layer was also adjusted and the wetting tension on the heat seal surface was set to 39 mN/m. At this time, the concentration of the antifogging agent in the entire film was about 1.1% by mass.

(Comparative Example 1)

A laminate of Comparative Example 1 was obtained in the same manner as in Example 1 except that the heat chamber 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 side of the heat seal layer was adjusted and the wetting tension of the surface of the heat seal layer was 33 mN/m.

(Comparative Example 3)

The heat chamber layer was not subjected to corona discharge treatment, the total thickness was set to 150 μm, and the thickness of each layer of (A)/(B1)/(B2)/(C) was 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 rotational speed of the cooling roll was changed so that it was adjusted and the take-up speed was adjusted.

(Comparative Example 4)

The corona discharge output on the side of the heat seal layer was adjusted, and the wetting tension of 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 as the resin for the intermediate layer (B2), LLDPE (1) and the antifogging agent (2) are mixed so that the mass ratio is 90/10. I used it. The concentration of the antifogging agent in the intermediate layer (B2) at this time was 2.0% by mass. Except for these, it carried out similarly to Example 1, and obtained the laminated body of Comparative Example 4. At this time, the concentration of the antifogging agent in 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 concentration of the antifogging agent at this time was 2.4% by mass in the intermediate layer (B1). Except for these, it carried out similarly to Example 1, and obtained the laminated body of Comparative Example 5. At this time, the concentration of the antifogging agent in the entire film was about 1.8% by mass.

(Comparative Example 6)

As the resin for the laminate layer (A), LDPE and the antifogging agent (2) were mixed and used so that the mass ratio was 99/1. The concentration of the antifogging agent in the laminate layer (A) at this time was 0.2% by mass. As resins for 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 concentration of the antifogging agent in the intermediate layers (B1) and (B2) at this time was 0.3% by mass. Except for these, it carried out similarly to Example 1, and obtained the laminated body of Comparative Example 6. At this time, the concentration of the antifogging agent in 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, it carried out similarly to Example 1, and obtained the laminated body of Comparative Example 8. At this time, the concentration of the antifogging agent in the entire 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. At this time, the concentration of the antifogging agent in the intermediate layer (B1) was 1.5% by mass. A laminate of Comparative Example 9 was obtained in the same manner as in Example 8 except that the corona treatment output on the side of the heat seal layer was also adjusted and the wetting tension of the heat seal surface was set to 44 mN/m. At this time, the concentration of the antifogging agent in the entire film was about 1.1% by mass.

(Comparative Example 10)

As 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. At this time, the concentration of the antifogging agent in the intermediate layer (B1) was 0.5% by mass. Further, as the resin for the intermediate layer (B2), LDPE and the 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 for these, it carried out similarly to Example 1, and obtained the laminated body of Comparative Example 10. At this time, the concentration of the antifogging agent in the entire film was about 1.1% by mass.

(Comparative Example 11)

A laminate of Comparative Example 11 was obtained in the same manner as in Example 1, except that the corona discharge treatment was not performed on the laminate layer side.

(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 concentration of the antifogging agent in the intermediate layer (B1) at this time was 1% by mass. Further, as resin for the intermediate layer (B2), LLDPE (1) and antifogging agent (2) were mixed and used so as to be 75/26 by mass. At this time, the concentration of the antifogging agent in the intermediate layer (B2) was 5%. No antifogging agent was added to the laminate layer (A) and the heat seal layer (C). Except for these, it carried out similarly to Example 1, and obtained the laminated body of Comparative Example 12. At this time, the concentration of the antifogging agent in the entire film was about 1.1% by mass.

(Comparative Example 13)

LLDPE (2) was used as the resin for the laminate layer (A), LLDPE (2) was used as the resin for the intermediate layer (B1), and LLDPE (1) was used as the resin for the intermediate layer (B2), As a resin for the heat seal layer (C), without adding an antifogging agent, polypropylene (1) and an antifogging agent (1) were mixed and used so that the mass ratio was 20/80. At this time, the concentration of the antifogging agent in the entire 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, but an appearance defect occurred due to remarkable surface roughness, and a good film was not obtained.

In the laminated film obtained by the said Example and the comparative example, the following evaluation was performed. The obtained results are shown in the table. In addition, the content of the compounding component of each layer in the table is the mass ratio in the layer.

[Evaluation of film appearance after aging]

By the coextrusion method, the appearance of the sample aged for 24 hours at 38°C of the film extruded from the T-die was visually confirmed.

○: Whitening due to bleeding of antifogging agent is not seen

×: Whitening caused by bleeding of the antifogging agent, deteriorating the transparency of the film

[Evaluation of laminate strength]

For the behavior of the laminate strength between the polyester film and the film obtained by the coextrusion method, the state when peeling at a rate of 300 mm/min using a tensile tester (A&D, Inc.) Evaluated in.

(Circle): By maintaining sufficient laminate strength, firm adhesion was confirmed between the polyester film and the film obtained by the coextrusion method.

X: Easy peeling was confirmed between the polyester film and the film obtained by the coextrusion method due to the lack of laminate strength.

[Anti-fogging effect confirmation test]

The obtained laminate was aged in an environment at 38°C for 24 hours, cut into 8cm×8cm, and a 71φ injection container (manufactured by Toko Co., Ltd.) in which 30ml of water at 40°C was put and heat sealed (pressure 64kgf). /cup, temperature 160°C, time 1.0 second), by visually using the following criteria, it was stored in a low temperature room at 3°C for 3 hours, and the antifogging effect was confirmed.

○: A continuous water film is formed on the film surface, and visibility is good

△: Good visibility even with fine water droplets attached to the film surface

×: With water droplets attached, poor visibility

[Heat room test]

The obtained laminate was cut out into 10 cm x 5 cm, and a sheet made of polypropylene having a thickness of 0.3 mm was stacked so that the heat seal surface was on the side of the polypropylene sheet, and a heat seal tester (precise heat sealer manufactured by Tester Sangyo) was used. The upper heat chamber bar adjusted to a predetermined temperature was set so as to come to the outermost layer side of the laminate, and heat chamber was performed under conditions of 0.2 MPa and 1 second.

[Evaluation of peeling strength]

The maximum strength at the time of peeling at a rate of 300 mm/min is determined by cutting out a 15 mm wide strip-shaped sample in the direction perpendicular to the heat-sealed part, and using a tensile tester (A&D Co., Ltd.). I did it.

[Table 1]

[Table 2]

[Table 3]

[Table 4]

As is clear from the above table, the antifogging laminated films of the present invention of Examples 1 to 12 were capable of achieving suitable antifogging properties and peeling strength. Moreover, it had a suitable film appearance, and the laminate strength was also suitable. On the other hand, the laminated films of Comparative Examples 1 to 6 and 9 to 11 were incompatible with suitable antifogging properties and peeling strength. In addition, the laminated films of Comparative Examples 7 to 8 and 12 to 13 were inferior in properties of the laminated film itself, and practical use was difficult.

Claims (13)

The linear polyethylene (a) is contained in an amount of 65% by mass or more based on the total amount of the resin component forming the laminate layer (A), and the laminate layer (A), which does not contain an antifogging agent, linear polyethylene (b1), and an antifogging agent ( An intermediate layer (B) containing b2), and a heat seal layer (C) containing a polypropylene resin (c1) and an antifogging agent (c2) were laminated in the order of (A)/(B)/(C). As a multilayer film made,
With respect to the total mass of the multilayer film, the total mass of the antifogging agent (b2) and the antifogging agent (c2) is included in the range of 0.8 to 1.6 mass%, and the wetting tension of both outer surfaces of the multilayer film is 35 to An anti-fogging multilayer film in the range of 45 mN/m and a total thickness of the multilayer film of 20 to 100 μm. The method of claim 1,
The intermediate layer (B) in the antifogging multilayer film is formed of a layer (B1) and a layer (B2) having different densities, and laminated in the order of (A)/(B1)/(B2)/(C) And the density of the linear polyethylene contained in the layer (B1) is higher than that of the linear polyethylene contained in the layer (B2). The method of claim 2,
The antifogging multilayer having a density of the linear polyethylene contained in the layer (B1) in the range of 0.920 to 0.945 g/cm 3 and the density of the linear polyethylene contained in the layer (B2) in the range of 0.880 to 0.920 g/cm 3 film. The method according to any one of claims 1 to 3,
The anti-fogging multilayer film having a density of the linear polyethylene (a) in the range of 0.920 to 0.945 g/cm 3. The method according to any one of claims 1 to 3,
An antifogging multilayer film in which the thickness ratio of the intermediate layer (B) to the total thickness of the multilayer film is in the range of 35 to 60%, and the thickness ratio of the heat seal layer (C) is in the range of 8 to 15%. The method according to any one of claims 1 to 3,
The antifogging multilayer film that the multilayer film is manufactured by a coextrusion lamination method. The method according to any one of claims 1 to 3,
The antifogging agents (b2) and (c2) are nonionic surfactants, the antifogging multilayer film. A laminate comprising the laminate layer (A) of the antifogging multilayer film according to any one of claims 1 to 3 and a thermoplastic resin film laminated thereon. A packaging material comprising the laminate according to claim 8. The method of claim 9,
A packaging material that is a cover material for food packaging containers. The method of claim 10,
A packaging material in which a seal surface of the food packaging container is a resin layer containing a propylene-based resin. delete delete