JP6839924B2 - Lid material - Google Patents

Description

The present invention relates to a lid material that seals an opening of a container such as food.

Conventionally, various resin laminated films have been used as a lid material for sealing and sealing the openings of various food containers. As a form of sealing the food container with such a lid material, a form in which the lid material is sealed so as not to protrude from the food container by a lid material having the same size as the opening of the food container, or a form larger than the opening. The opening is sealed by the lid material, and the lid material protruding from the opening is bent along the end of the opening and sealed so as to cover the end of the opening. Since the latter form makes it easy to obtain a high-class design, it is also applicable to dairy products such as pudding, jelly, yogurt and other dairy products sold at convenience stores and supermarkets, and food packaging containers such as parfaits that are distributed in large quantities. There is an increasing demand for lid materials that can be used in.

In the case of a lid material that is bent and sealed along the end of the opening, if the bent part is lifted after bending, it will be packed in a box, and the transportation efficiency will deteriorate, the occupancy rate of the exhibition space will increase, and the design will be impaired. Sex is required. Conventionally, as a lid material having good dead-holding property, a lid material having a metal foil such as aluminum foil in the layer structure has been used, but it is said that the lid material containing aluminum foil is difficult to separate. There has been a problem at the time of disposal and a problem that it is difficult to inspect foreign matter contamination by a metal detector, so a lid material that does not use aluminum foil has been required.

In response to these demands, as a lid material with good dead-holding properties without using aluminum foil, a paper base material is placed in the intermediate layer, biaxially stretched polypropylene on one side, polyethylene terephthalate on the other side, and a sealant layer. Proposed multi-layer lid materials having a laminated structure (see Patent Document 1) and lid materials in which a cyclic polyolefin resin and an olefin resin are laminated (see Patent Document 2).

Japanese Unexamined Patent Publication No. 2004-136918 Japanese Unexamined Patent Publication No. 2012-153420

However, since the lid material using a paper base material is mainly composed of paper having no moisture resistance, it has a complicated structure for suppressing moisture permeability, and as a result, the number of layers becomes complicated in order to form the structure. , The number of production processes tends to increase, and the thickness of the final film tends to increase, and the ease of penetration and dead hold are worse than those of the lid material using aluminum foil, which is inferior in practicality. It was.

The lid material using the cyclic polyolefin resin has a suitable dead-hold property, but it is a lid material that is supposed to eat and drink the contents with a straw or the like, and does not have an easy-opening property. ..

Further, in food applications, an interface peeling type easy-opening property that does not easily cause roughening of the opened surface is preferred, but in order to realize the above-mentioned dead-holding property and easy-opening property for a packaging container using a propylene resin, each of them is used. Although it is considered to have multiple layers of functional configurations, there is a high demand for cost reduction by reducing the volume of lid materials for foods, and it is possible to realize a thin lid material with dead hold and easy opening properties. It was desired.

An object to be solved by the present invention is to provide a lid material having suitable dead hold property and easy opening property even if it is thin.

The present invention is a lid material used for a container having a surface to be sealed containing a polypropylene-based resin, which comprises a laminate of a sealant film and a base film, and the sealant film contains a cyclic olefin-based resin. A sealant film in which a laminate layer (A), an intermediate layer (B) containing an olefin resin, an intermediate layer (C) containing a cyclic olefin resin, and a seal layer (D) containing an olefin resin are laminated. The laminate layer (A) contains a cyclic olefin resin (a1) having a glass transition temperature of 100 ° C. or lower and a cyclic polyolefin resin (a2) having a glass transition temperature of more than 100 ° C., and is a laminate layer (A). ), The content of the cyclic olefin-based resin in the resin component is 80% by mass, and the glass transition temperature in the cyclic olefin-based resin is 100 ° C. or lower as opposed to the cyclic olefin-based resin (a1) having a glass transition temperature of 100 ° C. The mass ratio (a1) / (a2) of the content with the cyclic polyolefin resin (a2) exceeding ° C. is 40/60 to 60/40, and the seal layer (D) is a metallocene catalyst as the olefin resin. The content of the linear polyethylene (d1) polymerized by the metallocene catalyst in the resin component contained in the seal layer (D), which contains the polymerized linear polyethylene (d1), is 80% by mass or more. The above-mentioned problem is solved by the lid material in which the total thickness of the sealant film is 35 μm or less and the thickness ratio of the total thickness of the laminate layer (A) and the intermediate layer (C) to the total thickness of the sealant film is 30 to 60%. It is the solution.

Since the lid material of the present invention has a suitable dead hold property even if it is thin, the lid material end portion is warped or the bent portion is caught even when the lid material is bent and sealed along the opening end portion of the container. Defects are unlikely to occur, and suitable design can be realized. Further, the lid material of the present invention is less likely to cause the seal layer to come off even when opened, can be preferably peeled off at the container / lid material interface, and does not leave adhesive residue on the container. The appearance is also good.

Further, the lid material of the present invention can realize not only the above-mentioned easy-opening property but also a suitable contaminant sealing property in which adhesion failure is unlikely to occur even when a foreign substance such as a package content adheres during heat sealing. Further, the lid material of the present invention can suppress deterioration of the flavor of the contents when used as a lid material for a packaging container for foods and the like.

The lid material of the present invention is a lid material used for a container having a surface to be sealed containing a polypropylene resin, and is a laminate layer (A) containing a cyclic olefin resin and an intermediate layer (B) containing an olefin resin. ), An intermediate layer (C) containing a cyclic olefin resin, and a sealant film (D) on which a seal layer (D) containing an olefin resin is laminated.
The laminated layer (A) contains a cyclic olefin resin (a1) containing 80% by mass or more of the cyclic olefin resin in the resin component and has a glass transition temperature of 100 ° C. or lower, and a glass transition temperature of 100. The cyclic polyolefin resin (a2) exceeding ° C. is contained at a ratio of 15/85 to 15/85 represented by (a1) / (a2), and the seal layer (D) is an olefin resin. The resin component contains 80% by mass or more of linear polyethylene (d1) polymerized with a metallocene catalyst.
Further, the total thickness of the sealant film is 35 μm or less, and the thickness ratio of the total thickness of the laminate layer (A) and the intermediate layer (C) to the total thickness of the sealant film is 30 to 60%.

[Laminate layer (A)]
The laminate layer (A) of the sealant film used in the present invention is a layer for laminating a base film and is a layer containing a cyclic olefin resin. Examples of the cyclic olefin-based resin include norbornene-based polymers, vinyl alicyclic hydrocarbon polymers, and cyclic conjugated diene polymers. Among these, norbornene-based polymers are preferable. The norbornene-based polymer includes a ring-opened polymer of a norbornene-based monomer (hereinafter referred to as “COP”) and a norbornene-based copolymer obtained by copolymerizing a norbornene-based monomer and an olefin such as ethylene (hereinafter referred to as “COP”). , "COC") and the like. In addition, COP and COC hydrogenated additives are particularly preferred. The weight average molecular weight of the cyclic olefin resin is preferably 5,000 to 500,000, more preferably 7,000 to 300,000.

The norbornene-based polymer and the norbornene-based monomer used as a raw material are alicyclic monomers having a norbornene ring. Examples of such norbornene-based monomers include norbornene, tetracyclododecene, ethilidene norbornene, vinyl norbornene, etylidetetracyclododecene, dicyclopentadiene, dimethanotetrahydrofluorene, phenylnorbornene, methoxycarbonylnorbornene, and methoxy. Examples thereof include carbonyltetracyclododecene. These norbornene-based monomers may be used alone or in combination of two or more.

The norbornene-based copolymer is a copolymer of the norbornene-based monomer and a copolymerizable olefin, and examples of such olefins have carbon atoms such as ethylene, propylene, and 1-butene. Examples thereof include olefins having 2 to 20; cycloolefins such as cyclobutene, cyclopentene and cyclohexene; and non-conjugated diene such as 1,4-hexadiene.

The content of the cyclic olefin-based resin in the laminate layer (A) is 80% by mass or more, preferably 90% by mass or more in the resin component constituting the laminate layer (A), and is suitable even if it is thin. Achieves a dead hold property.

Further, in the laminate layer (A), as the cyclic olefin resin, a cyclic olefin resin (a1) having a glass transition temperature of 100 ° C. or lower and a cyclic polyolefin resin (a2) having a glass transition temperature of more than 100 ° C. are contained. The ratio of the contents of the cyclic olefin resin (a1) having a glass transition temperature of 100 ° C. or lower and the cyclic polyolefin resin (a2) having a glass transition temperature of more than 100 ° C. in the cyclic olefin resin (a1) / ( a2) is contained in a mass ratio of 15/85 to 85/15. By containing cyclic olefin resins having different glass transition temperatures in the mass ratio, a lid material having suitable dead hold property and contaminant sealing property can be realized. Further, in addition to the heat resistance and rigidity of the lid material, it becomes easy to suitably combine performances such as take-back suitability at the time of film formation or slitting, and bag breakage resistance against dropping. The mass ratio (a1) / (a2) is preferably 20/80 to 80/20, more preferably 30/70 to 70/30, and even more preferably 40/60 to 60/40. The glass transition temperature (Tg) is a value obtained by measuring with DSC.

As a commercially available product that can be used as the cyclic olefin resin used in the present invention, examples of the ring-opening polymer (COP) of the norbornene-based monomer include "ZEONOR" manufactured by Nippon Zeon Co., Ltd., and the norbornene-based monomer is used. Examples of the copolymer (COC) include "Apel" manufactured by Mitsui Kagaku Co., Ltd. and "TOPAS" manufactured by Polyplastics Co., Ltd.

[Intermediate layer (B)]
The intermediate layer (B) of the sealant film used in the present invention contains an olefin resin. By using the intermediate layer (B), peeling between the laminated layer (A) and the intermediate layer (C) described later can be suppressed. The content of the olefin resin is preferably 80% by mass or more, more preferably 90% by mass or more, and 95% by mass or more in the resin component contained in the intermediate layer (B). More preferred.

As the olefin-based resin, various polyethylene-based resins and polypropylene-based resins can be used, and olefin-based resins other than the cyclic olefin-based resin can be preferably used. Examples of the polyethylene-based resin include polyethylene resins such as ultra-low density polyethylene (VLDPE), linear low density polyethylene (LLDPE), low density polyethylene (LDPE), linear medium density polyethylene (LMDPE), and medium density polyethylene (MDPE). , Polyethylene-vinyl acetate copolymer (EVA), ethylene-methylmethacrylate copolymer (EMMA), polyethylene-ethylacrylate copolymer (EEA), ethylene-methylacrylate (EMA) copolymer, ethylene-ethylacrylate -Eethylene copolymers such as maleic anhydride copolymer (E-EA-MAH), ethylene-acrylic acid copolymer (EAA), ethylene-methacrylic acid copolymer (EMAA); and even polyethylene-acrylic acid. Examples thereof include an ionomer of a copolymer and an ionomer of an ethylene-methacrylic acid copolymer, and two or more of them may be used alone or in admixture of two or more. Among these, VLDPE, LDPE, LLDPE, and LMDPE are preferable, and LMDPE is particularly preferable, because it is easy to obtain suitable dead hold property, curl resistance, and the like.

The LDPE may be a branched low-density polyethylene obtained by a high-pressure radical polymerization method, and is preferably a branched low-density polyethylene obtained by homopolymerizing ethylene by a high-pressure radical polymerization method.

LLDPE is an α-olefin such as butene-1, hexene-1, octene-1, 4-methylpentene, etc., which is composed mainly of ethylene monomer by a low-pressure radical polymerization method using a single-site catalyst. Is copolymerized. The comonomer content in LLDPE 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 site, the molecular weight distribution of the obtained resin is sharper than that of the multi-site catalyst having a non-uniform active site. It is preferable because it is possible to obtain a resin having physical properties that is less likely to precipitate and has excellent seal strength stability and blocking resistance.

The density of the polyethylene resin is preferably ^{0.880 to 0.940 g / cm 3.} When the density is within this range, it has appropriate rigidity, excellent mechanical strength such as heat seal strength and pinhole resistance, and film film forming property and extrusion suitability are improved. The melting point is preferably in the range of 60 to 130 ° C, more preferably 70 to 120 ° C. When the melting point is in this range, the processing stability (dead hold property) and the coextrusion processability with the cyclic olefin resin are improved. The MFR (190 ° C., 21.18N) of the polyethylene resin is preferably 2 to 20 g / 10 minutes, more preferably 3 to 10 g / 10 minutes. When the MFR is in this range, the extrudability of the film is improved.

Since such a polyethylene-based resin has good compatibility with a cyclic olefin-based resin, transparency when laminated can be maintained. Further, without using an adhesive resin or the like, the interlayer adhesive strength with the laminate layer (A) and the intermediate layer (C) can be maintained, and since it has flexibility, the pinhole resistance is also good. Further, when improving the pinhole resistance, it is preferable to use VLDPE or LLDPE.

When the material of the liquid-filled container having an opening is polystyrene or polyester resin, it is a polyethylene resin having adhesiveness, and in order to maintain an appropriate sealing strength, an ethylene-vinyl acetate copolymer (EVA) is used. ) Alone, using this EVA as a base resin, one or more of rosin, hydrogenated rosin, rosin ester derivative, polymerized rosin, terpene, modified terpene resin, aliphatic petroleum resin, styrene resin, etc. are mixed and modified. It is preferable to use modified EVA or the like, and modified EVA is particularly preferable. Specific examples of this modified EVA include modified polyethylene VMX manufactured by Mitsubishi Chemical Corporation.

Examples of polypropylene-based resins include propylene homopolymers and propylene / α-olefin random copolymers, such as propylene-ethylene copolymers, propylene-butene-1 copolymers, and propylene-ethylene-butene-1 copolymers. , Metallocene-catalyzed polypropylene and the like. Each of these may be used alone or in combination. A propylene-α-olefin random copolymer is preferably used, and a propylene / α-olefin random copolymer polymerized using a metallocene catalyst is particularly preferable. When these polypropylene-based resins are used as the intermediate layer (B), the heat resistance of the film is improved and the softening temperature can be raised. Therefore, boil at 100 ° C. or lower, hot filling, or 100 ° C. or higher. It can be suitably used as a lid material having excellent steam / high-pressure heat sterilization characteristics such as retort sterilization.

Further, these polypropylene-based resins preferably have an MFR (230 ° C.) of 0.5 to 30.0 g / 10 minutes and a melting point of 110 to 165 ° C., and more preferably MFR (230 ° C.) of 2. It has a melting point of 115 to 162 ° C. at 0 to 15.0 g / 10 minutes. When the MFR and the melting point are in this range, the shrinkage of the lid material is small when the resin layer (B) is used as the heat seal layer, and the film forming property of the film is also improved. Of course, the melting point is selected in relation to the glass transition temperature Tg of the cyclic olefin resin, as described for the polyethylene resin.

[Intermediate layer (C)]
The sealant film used in the present invention further has an intermediate layer (C) containing a cyclic olefin resin. By having the intermediate layer (C), excellent curl resistance and dead hold property can be realized, and suitable easy opening property can be easily realized.

As the cyclic olefin resin used in the intermediate layer (C), the cyclic olefin resin used in the laminate layer (A) can be preferably used, and the content of the cyclic olefin resin in the intermediate layer (C) is also high. The same range as the above laminated layer can be preferably used. When forming the sealant film, the laminate layer (A) and the intermediate layer (C) may have the same composition or may have different composition.

[Seal layer (D)]
The sealant film used in the present invention has a seal layer (D) containing an olefin resin as the other surface layer of the laminate layer (A). In the seal layer (D), as the olefin resin, linear polyethylene (d1) polymerized with a metallocene catalyst is used in an amount of 80% by mass or more of the resin component contained in the seal layer (D). Even in the multilayer film having a plurality of layers of the cyclic olefin resin, the polypropylene resin can exhibit a sealing property suitable for a container and can be easily peeled off.

As the linear polyethylene, LLDPE polymerized by the metallocene catalyst exemplified in the resin layer (B) can be particularly preferably used, and LMDPE polymerized by using the metallocene catalyst is particularly preferable. Among them, a polyethylene resin having a molecular weight distribution (Mw / Mn) of 3 or less, which is represented by the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn), is preferable.

The density of LLDPE used for the seal layer (D) ^{is preferably 0.900 g / cm 3} or more, and more preferably 0.905 to 0.920 g / cm ³ . By setting the density of LLDPE within the above range, it is possible to realize suitable easy-opening property and contaminant sealing property.

[Sealant film]
The sealant film used in the present invention is a multi-layer film having the above-mentioned laminate layer (A), intermediate layer (B), intermediate layer (C) and seal layer (D), and the total thickness thereof is 35 μm or less. .. Although other arbitrary layers may be provided between the layers, the film having a four-layer structure can be particularly preferably used. In the present invention, by using the sealant film, although the total thickness is as thin as 35 μm or less, it has suitable dead hold property, contaminant sealing property, and excellent easy opening property. It also has excellent curl resistance.

As for the thickness of each layer, the thickness of the laminate layer (A) is preferably 3 to 9 μm, more preferably 5 to 8 μm because of dead hold property and curl resistance. The thickness of the intermediate layer (B) is preferably 9 to 18 μm, which improves rigidity maintenance and contamination sealing, and more preferably 10 to 16 μm. The thickness of the intermediate layer (C) is preferably 3 to 9 μm, more preferably 5 to 8 μm because of dead hold and curl resistance. The thickness of the seal layer (D) is preferably 2 to 10 μm, more preferably 2 to 7 μm because of dead hold property, curl resistance, and opening property.

Further, in the present invention, the thickness ratio of the total thickness of the laminated layer (A) and the intermediate layer (C) to the total thickness of the sealant film is 30 to 60%. By setting the thickness ratio, a suitable dead hold property can be realized, and a suitable curl resistance can be easily obtained.

As necessary, each layer constituting the sealant film has an antifogging agent, an antistatic agent, a heat stabilizer, a nucleating agent, an antioxidant, a lubricant, an antiblocking agent, a mold release agent, an ultraviolet absorber, and a coloring agent. Such components can be added as long as the object of the present invention is not impaired. In particular, in order to impart processing suitability during molding, the friction coefficient of the laminate layer (A) and the seal layer (D) is preferably 1.5 or less, particularly 1.0 or less, so that the surface layer of the lid material can be used. It is preferable to appropriately add a lubricant, an antiblocking agent, or an antistatic agent to the corresponding resin layer.

Further, it is preferable that the surface of the laminate layer (A) is treated so that the surface tension of the surface of the sealant film is 40 dyne / cm or more, preferably 42 dyne / cm or more. Examples of such a treatment method include corona 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. Corona treatment is preferable. By performing such a surface treatment, it becomes easy to laminate the base film on the surface layer.

The method for producing the sealant film is not particularly limited, but for example, each resin or resin mixture used for each layer is heated and melted by a separate extruder, and is in a molten state by a method such as a coextrusion multilayer die method or a feed block method. Examples thereof include a coextrusion method in which the film is 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 having excellent hygiene and excellent cost performance can be obtained. Of these, the T-die chill roll method, which can perform melt extrusion at a relatively high temperature, is preferable because it is easy to suppress deterioration of the film appearance during coextrusion processing and it is easy to form a uniform layer structure.

[Lid material]
The lid material of the present invention is a lid material made of a laminate in which a base film is laminated on the surface layer of the sealant film. The base film is not particularly limited as long as it does not impair the sealing property and dead-hold property. For example, biaxially stretched polyester (PET), easily tearable biaxially stretched polyester (PET), and biaxially stretched polypropylene are used. (OPP), co-extruded biaxially stretched polypropylene with ethylene vinyl alcohol copolymer (EVOH) as the central layer, biaxially stretched ethylene vinyl alcohol copolymer (EVOH), and polyvinylidene chloride (PVDC) coated coextruded di. Examples thereof include axially stretched polypropylene and biaxially stretched nylon. Examples of the bonding method include dry lamination, wet lamination, non-solvent lamination, extrusion lamination and the like.

Examples of the adhesive used in the dry lamination include a polyether-polyurethane adhesive, a polyester-polyurethane adhesive and the like.

The lid material of the present invention is used as a lid material for tightly sealing a container having an opening by heat sealing, and as a material for a container having this opening, the outermost surface layer thereof. It is preferable that the material (the portion where the lid material is heat-sealed) is a resin layer containing polypropylene-based resin as a main component because it is easy to seal by heat-sealing. Further, when the material forming the container is also made of resin, it is preferable from the viewpoint that the contents can be taken out and then treated as resin waste together with the container.

(Example 1)
Each layer of the laminate layer (A) containing the cyclic olefin, the intermediate layer (B) containing the olefin resin layer, the resin layer (C) of the intermediate layer containing the cyclic olefin resin, and the heat-sealing seal layer (D) The following resins were used as the resin components to be formed, and the resin forming each layer and the resin mixture were prepared.
<Laminate layer (A)>
Ring-opening polymer of norbornene-based monomer ("Topas 8007F" manufactured by Polyplastics Co., Ltd., MFR: 15 g / 10 minutes (260 ° C., 21.18N), glass transition temperature: 70 ° C.; hereinafter, "COC (1)" 50 parts by mass, ring-opening polymer of norbornene-based monomer (“Apel APL6015T” manufactured by Mitsui Chemicals Co., Ltd., MFR: 10 g / 10 minutes (260 ° C., 21.18N), glass transition temperature: 145 ° C.; It is called "COC (2)") 50 parts by mass <intermediate layer (B)>
Linear medium density polyethylene polymerized by metallocene catalyst (density: 0.930 g / cm ³ , melting point 125 ° C., MFR: 5 g / 10 minutes (190 ° C., 21.18 N), molecular weight distribution (Mw / Mn) 2. 5; Hereinafter referred to as "LMDPE") 100 parts by mass <intermediate layer (C)>
COC (1) 50 parts by mass, COC (2) 50 parts by mass <Seal layer (D)>
Linear low-density polyethylene polymerized with a metallocene catalyst (density: 0.920 g / cm ³ , melting point 110 ° C., MFR: 5 g / 10 minutes (190 ° C., 21.18 N), molecular weight distribution (Mw / Mn) 2. 5; Hereinafter referred to as "LLDPE (1)") 100 parts by mass

These resins are used as an extruder for the laminate layer (A) (diameter 50 mm), an extruder for the intermediate layer (B) (diameter 50 mm), an extruder for the intermediate layer (C) (diameter 50 mm), and a seal layer (D), respectively. It is supplied to an extruder (diameter 40 mm) and melted at 200 to 270 ° C., and the melted resin is coextruded by a T-die / chill roll method having a feed block (feed block and T-die temperature: 250 ° C.). ), And co-melt extrusion is performed. The film has a four-layer structure of (A) / (B) / (C) / (D), and the thickness of each layer is 6 μm / 15 μm / 6 μm /. After obtaining a coextruded multilayer film having a size of 3 μm (30 μm in total), the surface of the laminate layer (A) was subjected to corona treatment. The surface tension of the corona-treated surface due to the wetting reagent was 42 dyne / cm.

After applying a urethane adhesive to 3.5 g / m ² on the corona-treated surface side, a biaxially stretched polyester film (thickness 12 μm, melting point 260 ° C., manufactured by Toyobo) was dry-laminated to obtain a laminate fill. ..

(Example 2)
A coextruded multilayer film was produced in the same manner as in Example 1 except that the resin components used for the laminate layer (A), the intermediate layer (B), and (C) were as follows, and the surface of the laminate layer (A) was corona-treated. Was given. The surface tension of the corona-treated surface due to the wetting reagent was 42 dyne / cm. A biaxially stretched polyester film was dry-laminated on the treated surface side in the same manner as in Example 1 to obtain a laminated film.
<Laminate layer (A), intermediate layer (C)>
COC (1) 50 parts by mass, COC (2) 47 parts by mass, linear low density polyethylene (density: 0.920 g / cm ³ , melting point 120 ° C, MFR: 5 g / 10 minutes (190 ° C, 21.18N) ; Hereinafter referred to as "LLDPE (2)") 3 parts by mass <intermediate layer (B)>
LMDPE 95 parts by mass, COC (1) 5 parts by mass

(Example 3)
A coextruded multilayer film was produced in the same manner as in Example 1 except that the resin components used for the laminate layer (A) and the intermediate layer (C) were as follows, and the surface of the laminate layer (A) was subjected to corona treatment. The surface tension of the corona-treated surface due to the wetting reagent was 43 dyne / cm. A biaxially stretched polyester film was dry-laminated on the treated surface side in the same manner as in Example 1 to obtain a laminated film.
<Laminate layer (A), intermediate layer (C)>
COC (1) 60 parts by mass, COC (2) 37 parts by mass, LLDPE (2) 3 parts by mass

(Example 4)
A coextruded multilayer film was produced in the same manner as in Example 1 except that the resin components used for the laminate layer (A) and the intermediate layer (C) were as follows, and the surface of the laminate layer (A) was subjected to corona treatment. The surface tension of the corona-treated surface due to the wetting reagent was 43 dyne / cm. A biaxially stretched polyester film was dry-laminated on the treated surface side in the same manner as in Example 1 to obtain a laminated film.
<Laminate layer (A), intermediate layer (C)>
COC (1) 40 parts by mass, COC (2) 57 parts by mass, LLDPE (2) 3 parts by mass

(Example 5)
A coextruded multilayer film was prepared in the same manner as in Example 1 except that the resin components and the intermediate layer (B) used for the laminate layer (A) and the intermediate layer (C) were as follows, and the surface of the laminate layer (A) was formed. Corona treatment was applied. The surface tension of the corona-treated surface due to the wetting reagent was 43 dyne / cm. A biaxially stretched polyester film was dry-laminated on the treated surface side in the same manner as in Example 1 to obtain a laminated film.
<Laminate layer (A), intermediate layer (C)>
COC (1) 50 parts by mass, ring-opening polymer of norbornene-based monomer (“Apel AP6013T” manufactured by Mitsui Chemicals, Inc., MFR: 15 g / 10 minutes (260 ° C., 21.18N), glass transition temperature: 125 ° C.; , "COC (3)") 47 parts by mass, LLDPE (2) 3 parts by mass <intermediate layer (B)>
LLDPE (2) 100 parts by mass

(Example 6)
A coextruded multilayer film was produced in the same manner as in Example 1 except that the resin components and the seal layer (D) used for the laminate layer (A), the intermediate layers (B), and (C) were as follows, and the laminate layer ( A) The surface was corona-treated. The surface tension of the corona-treated surface due to the wetting reagent was 43 dyne / cm. A biaxially stretched polyester film was dry-laminated on the treated surface side in the same manner as in Example 1 to obtain a laminated film.
<Laminate layer (A), intermediate layer (C)>
COC (1) 50 parts by mass, COC (2) 47 parts by mass, LLDPE (2) 3 parts by mass <Intermediate layer (B)>
LMDPE 95 parts by mass, COC (1) 5 parts by mass <Seal layer (D)>
90 parts by mass of LLDPE (1), 10 parts by mass of COC (1)

(Example 7)
A coextruded multilayer film was produced in the same manner as in Example 1, and the surface of the laminate layer (A) was subjected to corona treatment. The surface tension of the corona-treated surface due to the wetting reagent was 43 dyne / cm. An aluminum-deposited biaxially stretched polyester film was dry-laminated on the treated surface side in the same manner as in Example 1 to obtain a laminated film.

(Example 8)
A coextruded multilayer film was produced in the same manner as in Example 1, and the surface of the surface layer (A) was subjected to corona treatment. The surface tension of the corona-treated surface due to the wetting reagent was 43 dyne / cm. A biaxially stretched polyamide film (ONY) was dry-laminated on the treated surface side in the same manner as in Example 1 to obtain a laminated film.

(Example 9)
A coextruded multilayer film was produced in the same manner as in Example 1 except that the resin components used for the laminate layer (A) and the intermediate layer (C) were as follows, and the surface of the laminate layer (A) was subjected to corona treatment. The surface tension of the corona-treated surface due to the wetting reagent was 43 dyne / cm. A biaxially stretched polyester film was dry-laminated on the treated surface side in the same manner as in Example 1 to obtain a laminated film.
<Laminate layer (A), intermediate layer (C)>
COC (1) 80 parts by mass, COC (2) 17 parts by mass, LLDPE (2) 3 parts by mass

(Example 10)
A coextruded multilayer film was produced in the same manner as in Example 1 except that the resin components used for the laminate layer (A) and the intermediate layer (C) were as follows, and the surface of the laminate layer (A) was subjected to corona treatment. The surface tension of the corona-treated surface due to the wetting reagent was 43 dyne / cm. A biaxially stretched polyester film was dry-laminated on the treated surface side in the same manner as in Example 1 to obtain a laminated film.
<Laminate layer (A), intermediate layer (C)>
COC (1) 20 parts by mass, COC (2) 77 parts by mass, LLDPE (2) 3 parts by mass

(Example 11)
A coextruded multilayer film was prepared in the same manner as in Example 1 except that the resin components used for the laminate layer (A), the intermediate layer (C), and the seal layer (D) were as follows, and the surface of the laminate layer (A) was formed. Corona treatment was applied. The surface tension of the corona-treated surface due to the wetting reagent was 43 dyne / cm. A biaxially stretched polyester film was dry-laminated on the treated surface side in the same manner as in Example 1 to obtain a laminated film.
<Laminate layer (A), intermediate layer (C)>
COC (1) 50 parts by mass, COC (2) 50 parts by mass <Seal layer (D)>
Linear low-density polyethylene polymerized with a metallocene catalyst (density: 0.905 g / cm ³ , melting point 95 ° C., MFR: 5 g / 10 minutes (190 ° C., 21.18 N), molecular weight distribution (Mw / Mn) 2. 6; Hereinafter referred to as "LLDPE (3)") 100 parts by mass

(Example 12)
A coextruded multilayer film was produced in the same manner as in Example 1 except that the resin components used for the laminate layer (A) and the intermediate layer (C) were as follows, and the surface of the laminate layer (A) was subjected to corona treatment. The surface tension of the corona-treated surface due to the wetting reagent was 43 dyne / cm. A biaxially stretched polyester film was dry-laminated on the treated surface side in the same manner as in Example 1 to obtain a laminated film.
<Laminate layer (A), intermediate layer (C)>
COC (1) 30 parts by mass, COC (2) 30 parts by mass, LLDPE (2) 40 parts by mass

(Example 13)
A coextruded multilayer film was prepared in the same manner as in Example 1 except that the resin components used for the laminate layer (A), the intermediate layer (C), and the seal layer (D) were as follows, and the surface of the laminate layer (A) was formed. Corona treatment was applied. The surface tension of the corona-treated surface due to the wetting reagent was 43 dyne / cm. Further, vacuum aluminum vapor deposition having a thickness of 500 Å was applied to the laminate layer side. A biaxially stretched polyester film was dry-laminated in the same manner as in Example 1 to obtain a laminated film.
<Laminate layer (A), intermediate layer (C)>
COC (1) 50 parts by mass, COC (2) 47 parts by mass, LLDPE (2) 3 parts by mass <Seal layer (D)>
LLDPE (1) 70 parts by mass, COC (1) 30 parts by mass

(Comparative Example 1)
The following resins were used as the resin components forming each of the laminate layer (A) and the seal layer (D), and the resin and the resin mixture forming each layer were prepared.
<Laminate layer (A)>
COC (2) 100 parts by mass <Seal layer (D)>
LMDPE 100 parts by mass

Each of these resins is supplied to the extruder for the laminate layer (A) (diameter 50 mm) and the extruder for the seal layer (D) (diameter 40 mm) and melted at 200 to 250 ° C., and the melted resin is fed block. The co-extruded multilayer film manufacturing apparatus (feed block and T-die temperature: 250 ° C.) of the T-die / chill-roll method is subjected to co-melt extrusion, and the layer structure of the film is (A) / (D). A coextruded multilayer film having a two-layer structure and having a thickness of 6 μm / 24 μm (30 μm in total) was obtained, and then the surface of the laminate layer (A) was subjected to corona treatment. The surface tension of the corona-treated surface due to the wetting reagent was 42 dyne / cm.

A urethane-based adhesive was applied to the corona-treated surface side to 3.5 g / m ² , and then a biaxially stretched polyester film (thickness 12 μm, melting point 260 ° C., manufactured by Toyobo Co., Ltd.) was dry-laminated to obtain a laminate fill. ..

(Comparative Example 2)
After obtaining a co-extruded multilayer film in which the thickness of each layer of the co-extruded multilayer film is 5 μm / 25 μm (30 μm in total) in the same manner as in Example 1 except that the resin component used for the seal layer (D) is as follows. , The surface of the laminate layer (A) was subjected to corona treatment. The surface tension of the corona-treated surface due to the wetting reagent was 43 dyne / cm. A biaxially stretched polyester film was dry-laminated in the same manner as in Comparative Example 1 to obtain a laminated film.
<Seal layer (D)>
Low density polyethylene polymerized with Ziegler-Natta catalyst (density: 0.895 g / cm ³ , melting point 85 ° C, MFR: 5 g / 10 minutes (190 ° C, 21.18 N), molecular weight distribution (Mw / Mn) 5; Hereinafter referred to as "LLDPE (4)") 100 parts by mass

(Comparative Example 3)
A co-extruded multilayer film having a thickness of 24 μm / 6 μm (30 μm in total) is obtained in the same manner as in Comparative Example 2 in which the resin component used for the laminate layer (A) is the following, and then laminated. The surface of the layer (A) was subjected to corona treatment. The surface tension of the corona-treated surface due to the wetting reagent was 43 dyne / cm. A biaxially stretched polyester film was dry-laminated in the same manner as in Comparative Example 1 to obtain a laminated film.
<Laminate layer (A)>
40 parts by mass of COC (1), 20 parts by mass of COC (2), 40 parts by mass of LLDPE (2)

(Comparative Example 4)
The thickness of each layer of the coextruded multilayer film is the same as in Example 1 except that the resin components used for the laminate layer (A), the intermediate layer (B), the intermediate layer (C), and the seal layer (D) are as follows. A film having a size of 5 μm / 6 μm / 5 μm / 14 μm (30 μm in total) was prepared, and the surface of the laminate layer (A) was subjected to corona treatment. The surface tension of the corona-treated surface due to the wetting reagent was 43 dyne / cm. A biaxially stretched polyester film was dry-laminated on the treated surface side in the same manner as in Example 1 to obtain a laminated film.
<Laminate layer (A), intermediate layer (C)>
COC (1) 40 parts by mass, COC (2) 20 parts by mass, LLDPE (2) 40 parts by mass <Intermediate layer (B)>
LLDPE (2) 100 parts by mass <Seal layer (D)>
Low density polyethylene [Density: 0.92 g / cm3, melting point 120 ° C., MFR: 5 g / 10 minutes (190 ° C., 21.18N); hereinafter referred to as "LDPE". ] To 100 parts by mass

(Comparative Example 5)
The thickness of each layer of the coextruded multilayer film is the same as in Example 1 except that the resin components used for the laminate layer (A), the intermediate layer (B), the intermediate layer (C), and the seal layer (D) are as follows. A film having a size of 6 μm / 13 μm / 6 μm / 5 μm (30 μm in total) was prepared, and the surface of the laminate layer (A) was subjected to corona treatment. The surface tension of the corona-treated surface due to the wetting reagent was 43 dyne / cm. A biaxially stretched polyester film was dry-laminated on the treated surface side in the same manner as in Example 1 to obtain a laminated film.
<Laminate layer (A), intermediate layer (C)>
COC (2) 100 parts by mass <Intermediate layer (B)>
LMDPE 100 parts by mass <Seal layer (D)>
LLDPE (4) 100 parts by mass

(Comparative Example 6)
A film having a thickness of 6 μm / 15 μm / 6 μm / 3 μm (total 30 μm) of each layer of the coextruded multilayer film was prepared in the same manner as in Example 1 except that the resin component used for the seal layer (D) was as follows. The surface of the surface layer (A) was subjected to corona treatment. The surface tension of the corona-treated surface due to the wetting reagent was 43 dyne / cm. A biaxially stretched polyester film was dry-laminated on the treated surface side in the same manner as in Example 1 to obtain a laminated film.
<Seal layer (D)>
LLDPE (4) 100 parts by mass

(Comparative Example 7)
A film having a thickness of 2 μm / 12 μm / 2 μm / 14 μm (total 30 μm) of each layer of the coextruded multilayer film was prepared in the same manner as in Example 1 except that the resin component used for the seal layer (D) was as follows. The surface of the laminate layer (A) was subjected to corona treatment. The surface tension of the corona-treated surface due to the wetting reagent was 43 dyne / cm. A biaxially stretched polyester film was dry-laminated on the treated surface side in the same manner as in Example 1 to obtain a laminated film.
<Seal layer (D)>
Propylene / α-olefin random copolymer polymerized using a metallocene catalyst [Density: 0.900 g / cm ³ , melting point 135 ° C., MFR: 4 g / 10 minutes (230 ° C., 21.18 N); ". ) 100 parts by mass

(Comparative Example 8)
After obtaining a co-extruded multilayer film in which the thickness of each layer of the co-extruded multilayer film is 6 μm / 24 μm (total 30 μm) in the same manner as in Comparative Example 1 except that the resin component used for the seal layer (D) is as follows. , The surface of the laminate layer (A) was subjected to corona treatment. The surface tension of the corona-treated surface due to the wetting reagent was 43 dyne / cm. A biaxially stretched polyester film was dry-laminated in the same manner as in Comparative Example 1 to obtain a laminated film.
<Seal layer (D)>
Adhesive acid-modified polyethylene [manufactured by Tosoh Corporation, density: 0.940 g / cm3, MFR: 28 g / 10 minutes (190 ° C., 21.18N) "MX28"; hereinafter, "EVA" 100 parts by mass

The films obtained in the above Examples and Comparative Examples were evaluated as follows. The results obtained are shown in the table below.

[Dead hold test, easy opening test]
The film obtained above is punched out at 80 mmφ with a tab portion (13 mm) in a PP container (outer diameter 70 mmφ, thickness 700 μm, flange width 5 mm) to obtain optimum heat seal strength at 140 ° C to 170 ° C. Adjusted and sealed. In order to secure a state of being bent 90 degrees or more, a lid for an overcap formed by molding a biaxially stretched polystyrene sheet was fitted from above the lid material, and the lid was left in a refrigerator at 0 ° C. for 5 hours. After that, the overcap lid was removed, the return angle of the lid material tab was measured, and the evaluation was made as follows.
Tab return angle 0 ° does not return ◎
0 to 20 ° back ○
20-45 ° back △
45 ° or more back ×

The opening strength after heat sealing was evaluated as follows. The tab portion was sandwiched between chucks, and the strength was measured with a tensile tester.
◯: 5N / 1 cup or more and 25N / 1 cup or less ×: Less than 5N / 1 cup, or larger than 25N / 1 cup (cannot be opened) or the film tears

[Contaminant sealing property (1)]
0.5 g of commercially available pudding was placed at the four corners on a circular PP container with a protrusion flange (90 mm diameter, flange width 7 mm, protrusion width 1 mm, protrusion height 0.7 mm, thickness 600 μm). After that, the prepared laminated film was sealed at 180 ° C. for 1 second at 0.2 MPa, and the sealing strength was measured.
⊚: 20 MPa or more ○: 12 MPa or more and less than 20 MPa ×: less than 12 MPa

[Curl property test]
Each multilayer film was cut out in 10 cm squares in length and width, and stored at 40 ° C. and 90% humidity for 24 hours. The film was spread on a flat surface, and the height at which both end faces were rolled up was measured and evaluated according to the following criteria.
〇: Less than 5 cm ×: 5 cm or more

As is clear from the above table, the lid materials of the present invention of Examples 1 to 13 had suitable dead hold property, easy opening property, and contaminant sealing property, and were also excellent in curl resistance. On the other hand, the lid materials of Comparative Examples 1 to 8 could not have these characteristics.

Claims (3)

A lid material used for a container having a surface to be sealed containing a polypropylene resin.
It consists of a laminate of a sealant film and a base film.
The sealant film contains a laminate layer (A) containing a cyclic olefin resin, an intermediate layer (B) containing an olefin resin, an intermediate layer (C) containing a cyclic olefin resin, and an olefin resin. A sealant film in which a seal layer (D) is laminated.
The laminate layer (A) contains a cyclic olefin resin (a1) having a glass transition temperature of 100 ° C. or lower and a cyclic polyolefin resin (a2) having a glass transition temperature of more than 100 ° C.
With the cyclic olefin resin (a1) in which the content of the cyclic olefin resin in the resin component contained in the laminate layer (A) is 80% by mass or more and the glass transition temperature in the cyclic olefin resin is 100 ° C. or less. The mass ratio (a1) / (a2) of the content with the cyclic polyolefin resin (a2) having a glass transition temperature exceeding 100 ° C. is 15/85 to 85/15.
The seal layer (D) contains linear polyethylene (d1) polymerized with a metallocene catalyst as an olefin resin.
The content of the linear polyethylene (d1) polymerized by the metallocene catalyst in the resin component contained in the seal layer (D) is 80% by mass or more.
The lid material is characterized in that the total thickness of the sealant film is 35 μm or less, and the thickness ratio of the total thickness of the laminate layer (A) and the intermediate layer (C) to the total thickness of the sealant film is 30 to 60%. .. The lid material according to claim 1, wherein the linear polyethylene (d1) is a linear polyethylene polymerized using a metallocene catalyst. The lid material according to claim 1 or 2, which has an aluminum-deposited layer on the surface of the sealant film on the laminated layer (A) side.