JP2019005934A - Lid material - Google Patents

Abstract

To provide a lid material that has excellent easy-peeling properties, can be produced at low cost, and hermetically seals a polyethylene container.SOLUTION: An easy-peeling lid material for a polyethylene container has at least three layers of an (A) layer, a (B) layer, and a (C) layer in this order, where the (A) layer has polyolefin satisfying the following requirements (a), (b), the (B) layer has an adhesive, and the (C) layer has at least one layer of a base material containing aluminum foil, where the(A) layer has a thickness of 10-30 μm, and a surface of the (C) layer in contact with (B) layer is the aluminum foil. (a) A density measured on the basis of JIS K6922-1 is 921-940 kg/m, and (b) a melt mass flow rate (MFR) measured on the basis of JIS K6922-1 is 10-100 g/10 min.SELECTED DRAWING: None

Description

  The present invention relates to a lid for a polyethylene container that is suitable for extrusion lamination and can be produced at low cost.

In recent years, due to the problem of industrial waste, food containers are being changed from polystyrene or polyvinyl chloride to polyethylene or polypropylene that does not generate harmful gases during combustion. In particular, a container using polyethylene or a container in which polyethylene is laminated on paper has been used.
Examples thereof include a yogurt container obtained by extrusion laminating polyethylene on paper, a multilayer container mainly composed of polyethylene for mayonnaise, ketchup and the like, and a polyethylene container such as an infusion bottle.

  The above-described container requires a lid material that can be completely sealed, can be handled safely without being broken during transportation, and has an easy peel property that can be opened by women and children when opened. For example, 1) a composition in which a resin (eg, polypropylene) that is basically difficult to adhere to polyethylene is mixed with a resin (eg, polyethylene, ethylene-vinyl acetate copolymer, etc.) that can be adhered to polyethylene. 2) A so-called hot melt composition obtained by mixing an ethylene-vinyl acetate copolymer with a tackifier, a low molecular weight wax, and the like. 3) A high molecular weight type hot melt composition in which the above hot melt type can be extruded. ) A composition in which low molecular weight polyethylene is blended with high molecular weight polybutene (see, for example, Patent Document 1), 5) Polyethylene easy-peeling adhesive (for example, patent) comprising polyethylene resin, crystalline polybutene resin, and low molecular weight wax Reference 2).

  However, the above composition has various problems and is not satisfactory as an easy-peel lid for a polyethylene container. That is, the composition of 1) is inferior in processability because it is mixed with resins that are hardly compatible with each other, and is not flexible enough to fill a step required for sealing a paper cup container, thereby preventing liquid leakage. Not suitable for. Further, when the adhesive strength is increased, a so-called stringing phenomenon in which the lid member breaks in a streak shape occurs, and the appearance after peeling is deteriorated. The composition of 2) has sufficient fluidity and sealing strength to fill the steps of the paper cup container, but a special coater is required at the time of processing, and since the heat resistance is inferior, the container is covered inside at the time of heat sealing. There is a risk of material contamination. Although the composition of 3) is excellent in heat resistance, it has high adhesive strength with polyethylene and is inferior in easy peel properties. Since the adhesive strength becomes lower as the heat seal temperature is lower, a method of sealing by limiting the use temperature is conceivable. However, since the temperature dependency is high, the variation in the adhesive strength is large, and there is a problem in quality as a product. In the composition of 4), when the melt mass flow rate (hereinafter referred to as MFR) measured in accordance with JIS K6922-1 of low density polyethylene is 20 g / 10 min or less, polyethylene which is one of the objects of the present invention is laminated. The peel strength is too high for the paper container or sheet, and so-called paper peeling that breaks the paper occurs. If the MFR of the low density polyethylene is set to 20 to 70 g / 10 minutes in order to maintain the easy peel property, the melt tension is low and the extrusion laminating property is inferior. The adhesive of 5) can be used without problems when the thickness of the polyethylene layer laminated on the inner surface of the paper container is 40 μm or more, but the polyethylene layer laminated on the inner surface of the paper container is, for example, about 30 μm. When it is thinned, the film strength of the polyethylene layer is weakened and easily broken, so that a paper peeling phenomenon is likely to occur. Moreover, since polybutene is generally expensive, there is a drawback that the composition is also expensive.

JP-A-1-315443 JP 2003-129018 A

  The present invention has been made in view of the above situation, and an object of the present invention is to provide a lid for a polyethylene container having easy peel performance that is suitable for extrusion lamination and can be produced at low cost. To do.

The present invention comprises at least three layers in the order of (A) layer, (B) layer, (C) layer, (A) polyolefin satisfying the following requirements (a) and (b), and (B) layer: Adhesive, (C) layer is made of at least one base material including aluminum foil, (A) layer thickness is 10-30 μm, and (C) layer is in contact with (B) layer is aluminum The present invention relates to an easy peel lid for a polyethylene container, which is a foil.
(A) The density measured based on JIS K6922-1 is 921-940 kg / m ³
(B) The melt mass flow rate (MFR) measured based on JIS K6922-1 is 10 to 100 g / 10 min. The present invention is described in detail below.

  Polyolefins used in the layer (A) constituting the lid material of the present invention are homopolymers or copolymers of α-olefins having 2 to 12 carbon atoms such as ethylene, propylene and 1-butene, and ethylene and vinyl. An ester, an acrylate ester, or a copolymer with acrylic acid is shown. For example, high pressure method low density polyethylene, high density polyethylene, medium density polyethylene, ethylene / 1-butene copolymer, ethylene / 1-hexene copolymer, ethylene / 1-octene copolymer, ethylene / 4-methyl-1 -Ethylene such as pentene copolymer, ethylene / vinyl acetate copolymer, ethylene / acrylic acid copolymer, ethylene / methacrylic acid copolymer, ethylene / acrylic acid ester copolymer, ethylene / methacrylic acid ester copolymer Polymer, polypropylene, propylene / ethylene copolymer, propylene / 1-butene copolymer, poly-1-butene, poly-1-hexene, poly-4-methyl-1-pentene, and the like. You may use individually or in combination of 2 or more types. Among these, high-density polyethylene, ethylene / α-olefin copolymer, or high-pressure method low-density polyethylene is preferable from the viewpoint of adhesion to the layer (B). These compositions are also preferable because they are excellent in extrusion laminate processability.

  In addition, it is preferable to mix | blend mutually compatible resin with the polyolefin used for the (A) layer which comprises the cover material of this invention from an adhesive viewpoint with a (B) layer.

From the viewpoint of easy opening and extrusion laminate processability, the composition ratio of the above composition is a high-density polyethylene (1) and / or a co-polymer of ethylene having a density of less than 940 kg / m ³ and α-olefin having 4 or more carbon atoms. The range of 0 to 90 parts by weight of the polymer (2) and 10 to 100 parts by weight of the high pressure method low density polyethylene (3) (the total of (1), (2) and (3) is 100 parts by weight) It is preferable that

Furthermore, the blending ratio of the composition is high density polyethylene (1) and / or ethylene having a density of less than 940 kg / m ³ and an α-olefin having 4 or more carbon atoms from the viewpoint of easy opening and extrusion lamination processability. 0 to 40 parts by weight of copolymer (2), 20 to 90 parts by weight of high-pressure low-density polyethylene (3a) having an MFR of 20 g / 10 min or more, and high-pressure low-density polyethylene (MFR of 5 g / 10 min or less) 3b) More preferably, it is 5 to 40 parts by weight (the sum of (1), (2), (3a) and (3b) is 100 parts by weight).

A method for producing such a high-density polyethylene and a copolymer of ethylene having a density of less than 940 kg / m ³ and an α-olefin having 4 or more carbon atoms is not particularly limited, but a Ziegler-Natta catalyst or a Philips catalyst, Examples thereof include high / medium / low pressure ion polymerization using a metallocene catalyst, and such a resin can be conveniently selected from commercially available products. For example, they are commercially available from Tosoh Corporation under the trade names Nipolon Hard, Nipolon-L and Nipolon-Z. In addition, the method for producing high-pressure low-density polyethylene can be exemplified by high-pressure radical polymerization, and such a resin can be conveniently selected from commercially available products, for example, under the trade name of Petrocene from Tosoh Corporation. It is commercially available.

The polyolefin used for the layer (A) constituting the lid material of the present invention has a density measured according to JIS K6922-1 (1997) of 921 to 940 kg / m ³ , preferably 921 to 935 kg / m ³ . More preferably, it is 921-930 kg / m < ³ >, Most preferably, it is 921-928 kg / m < ³ >. When the density is less than 921 kg / m ^3, the opening strength when heat-sealing with a container having polyethylene as an adhesive layer is high, and the easy-opening property is poor, which is not preferable. On the other hand, when the density exceeds 940 kg / m ³ , the adhesiveness with the layer (B) is inferior, which is not preferable.

  The polyolefin used in the layer (A) constituting the lid material of the present invention has an MFR measured by JIS K6922-1 (1997) of 10 to 100 g / 10 minutes, preferably 10 to 70 g / 10 minutes. A more preferable range is 10 to 50 g / 10 min. When the MFR is less than 10 g / 10 minutes, the opening strength when heat-sealing with a polyethylene container is high, and the easy-opening property is poor, which is not preferable. Moreover, when exceeding 100 g / 10min, since it is inferior to extrusion laminate moldability and there exists a possibility that the stable production may become difficult, it is unpreferable.

  The polyolefin used in the layer (A) constituting the lid material of the present invention is usually used for polyolefins such as antioxidants, lubricants, neutralizers, antiblocking agents, surfactants, slipping agents, etc. as necessary. It is also possible to add a thermoplastic resin such as an additive and other polyolefins.

  The polyolefin composition used for the layer (A) constituting the lid material of the present invention can be produced by a commonly used resin mixing device. For example, a single-screw extruder, a twin-screw extruder, a Banbury mixer, a pressure kneader, a melt kneader such as a rotating roll, a Henschel mixer, a V blender, a ribbon blender, a tumbler, and the like can be given. When a melt kneading apparatus is used, the melting temperature is preferably about the melting point of polyolefin to about 350 ° C.

  The adhesive used for the layer (B) constituting the lid material of the present invention is not particularly limited, and polyurethane adhesive, polybutadiene adhesive, polyisocyanate adhesive, polyurea adhesive, epoxy adhesive, acrylic adhesive Examples thereof include polyamide adhesives. Among them, a polyurethane adhesive that can easily control the adhesiveness and the elastic modulus, and a polybutadiene adhesive that does not require aging and that can use an alcohol solvent and has excellent handling properties are preferable.

The adhesive used for the layer (B) constituting the lid material of the present invention has a storage elastic modulus E ′ at 20 ° C. of 1.0 × 10 ⁶ to 2 from the viewpoint of opening appearance when heat-sealed with a polyethylene container. It is preferable that it is 5 × 10 ⁸ Pa. If an adhesive having E 'in this range is used, the unsealed appearance becomes good.

  The adhesive used for the layer (B) constituting the lid material of the present invention has a glass transition temperature measured from JIS K7121 of −30 to + 10 ° C. from the viewpoint of opening appearance when heat-sealed with a polyethylene container. Is preferred.

  The polyurethane adhesive is composed of a polyol component having at least two hydroxyl groups in the molecule and an isocyanate component having at least two isocyanate groups in the molecule. Examples of the polyol component include polyurethane polyol, polyester polyol, polyether polyol, acrylic polyol, polyolefin polyol, and the like, and two or more kinds of such polyol components may be mixed and used. Among these, polyurethane polyols, polyester polyols and polyether polyols that can easily control the glass transition temperature and the storage elastic modulus are preferable. In addition, an aliphatic system containing 30% by weight or more of the dicarboxylic acid component, the diol component, and the diester component constituting the polyurethane polyol or polyester polyol is preferable because the glass transition point and the storage elastic modulus are low and the unsealed appearance is improved.

  On the other hand, examples of the isocyanate component include araliphatic diisocyanate, aliphatic diisocyanate, and alicyclic diisocyanate. Specific examples of the araliphatic diisocyanate include 1,3- or 1,4-xylylene diisocyanate or a mixture thereof, 1,3- or 1,4-bis (1-isocyanato-1-methylethyl) benzene or a mixture thereof. , Ω, ω′-diisocyanato-1,4-diethylbenzene and the like. Specific examples of the aliphatic diisocyanate include hexamethylene diisocyanate, tetramethylene diisocyanate, 2-methyl-pentane-1,5-diisocyanate, 3-methyl-pentane-1,5-diisocyanate, lysine diisocyanate, and trioxyethylene diisocyanate. Can be mentioned. Specific examples of the alicyclic diisocyanate include isophorone diisocyanate, cyclohexyl diisocyanate, hydrogenated diphenylmethane diisocyanate, norbornane diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated xylene diisocyanate, hydrogenated tetramethylxylene diisocyanate and the like.

  Further, as an isocyanate component, it is obtained by a reaction of a biuret, dimer, trimer, dimer / trimer, or uretonimine-modified polymer such as the diisocyanate or a bifunctional or higher functional polyol with the diisocyanate or the polymer. And organic polyisocyanate-modified products such as adducts of polyisocyanates.

  These can be used alone or in admixture of two or more.

  Such polyurethane adhesives can be appropriately selected from commercially available products, and are commercially available from Tosoh Corporation under the trade names such as Nipponran and Coronate.

  Adjustment of a glass transition temperature and a storage elastic modulus can be adjusted with selection of a polyol component or an isocyanate component, and the compounding ratio of a polyol component and an isocyanate component. Moreover, it is preferable that the ratio of the number of hydroxyl groups of the polyol component and the number of isocyanate groups of the isocyanate component (NCO / OH) in the range of 0.5 to 10 is excellent in easy-openability and unsealed appearance.

  The solvent used for diluting the adhesive is not particularly limited, but esters such as ethyl acetate, butyl acetate and cellosolve acetate, ketones such as acetone, methyl ethyl ketone, isobutyl ketone and cyclohexanone, tetrahydrofuran, dioxane and the like Exemplified ethers, aromatic hydrocarbons such as toluene and xylene, halogenated hydrocarbons such as methylene chloride and ethylene chloride, alcohols such as dimethyl sulfoxide, dimethyl sulfoamide, methanol, ethanol and isopropanol, water, etc. be able to.

  The polybutadiene adhesive is a liquid polymer dispersed in water with polybutadiene modified with a hydroxyl group or a carboxyl group at the end of the polybutadiene chain, and can be diluted with water or alcohol. In particular, those derived from 1,2-polybutadiene are particularly preferred.

  Such a polybutadiene adhesive can be appropriately selected from commercially available products, and are commercially available from Dainichi Seika Co., Ltd. under the trade names such as Seikadyne 4300 and Toyo Morton Co., Ltd., EL-452. .

The coating amount of the adhesive used for the layer (B) constituting the lid material of the present invention is not particularly limited, and the range of 0.002 to 0.20 g / m ² is excellent in adhesiveness and easy-openability. preferably, a more preferred range of 0.02~0.10g / ^{m 2,} more preferably from 0.025~0.075g / ^{m 2.}

  Such an adhesive can be applied to the base material of the (C) layer with a coater attached to a known laminator. In particular, a plane roll is preferable because of excellent coating accuracy when the thickness of the adhesive is small.

  The thickness of the adhesive used for the layer (B) constituting the lid material of the present invention is not particularly limited, and a range of 0.01 to 3 μm is excellent in adhesiveness and easy-openability, preferably 0.1 to 0.1 μm. The range of 1 μm is more suitable, and more preferably 0.1 to 0.7 μm.

  The base material used for the (C) layer constituting the lid material of the present invention is composed of at least one layer including an aluminum foil, and the surface in contact with the (B) layer is the aluminum foil. The structure other than the aluminum foil of the substrate is not particularly limited. For example, polyesters such as polyethylene terephthalate and polybutylene terephthalate, polyamides such as nylon 6 and nylon 66, saponified ethylene-vinyl acetate copolymer, Laminate one or more layers of films, cellophane, paper, etc. made of polymer polymers such as polyvinyl alcohol, polypropylene resin, acrylic resin, polymethylpentene, polyvinyl chloride, polyvinylidene chloride, polycarbonate, cellulose resin, etc. be able to.

  The lid material of the present invention preferably has a breaking strength Fb of a film made of polyolefin of the (A) layer having a width of 1 to 4 N / 15 mm. When the breaking strength Fb is within this range, it is preferable that the opening strength when the lid material is heat-sealed with a container having polyethylene as an adhesive layer is appropriate.

  The breaking strength Fb of the film made of polyolefin of the (A) layer is such that the film obtained by peeling the (A) layer from the (B) layer is formed into a 15 mm wide strip and the tensile speed is 300 mm / min, and the distance between chucks. It is the strength at break when pulled under the condition of 40 mm.

  In addition, when peeling the film of (A) layer from (B) layer, you may use an organic solvent and water in order to reduce the adhesive strength between layers. It is preferable to peel the film in a state where it is not stretched as much as possible.

  In the lid material of the present invention, the delamination strength Fd (unit: N / 15 mm width) of the (A) layer and the (C) layer after heat sealing at 170 ° C. and the breaking strength Fb satisfy the following relationship: It is preferable.

Fd × 0.8> Fb
If this relationship is satisfied, when the lid is heat-sealed with a container having polyethylene as an adhesive layer and opened, abnormal peeling between the (A) layer and the (C) layer at the outer edge of the seal portion (hereinafter referred to as delamination). Is less likely to occur, and the unsealed appearance is favorable.

  The delamination strength Fd between the (A) layer and the (C) layer after heat sealing at 170 ° C. is a low density polyethylene of an extruded laminate film comprising a low density polyethylene layer having a thickness of 25 μm and a polyethylene terephthalate (PET) layer having a thickness of 12 μm. (A) layer of the cover material and the (A) layer of the lid material were heat-sealed at 170 ° C. for 1 second, formed into a strip shape having a width of 15 mm, and pulled under the conditions of a tensile speed of 300 mm / min and a chuck distance of 40 mm ( It is a steady value of the delamination strength between the A) layer and the (C) layer.

  The lid material of the present invention can be produced by a known laminating method. Examples of the laminating method include extrusion lamination, sandwich lamination, dry lamination, non-solvent dry lamination, wet lamination, thermal lamination and the like, and extrusion lamination is preferred from the viewpoint of cost and thin film moldability.

In order to obtain good adhesion when subjected to extrusion lamination, it is preferable that at least the surface in contact with the adhesive (B) of the molten film made of polyolefin extruded from the die is oxidized by air or ozone gas. When the oxidation reaction with air proceeds, the temperature of the molten film extruded from the die is preferably 200 ° C. or higher. When the oxidation reaction with ozone gas proceeds, the treatment amount of ozone gas is 1 m of the molten film extruded from the die. It is preferable that it is 0.5 mg or more per ² .

  The film thickness of the (A) layer which comprises the cover material of this invention is 10-30 micrometers, Preferably it is 15-25 micrometers. (A) When the film thickness of the layer is less than 10 μm, when the lid material is heat-sealed to a paper container having polyethylene as the adherend surface, a level difference resulting from the overlap of paper existing in the flange portion of the container Filling with molten resin becomes difficult, and the sealing performance of the container may be impaired. When the film thickness of the (A) layer exceeds 30 μm, the breaking strength of the film made of polyolefin of the (A) layer becomes high, and when the lid is heat-sealed with a polyethylene container and opened at the outer edge of the seal part Delamination tends to occur and the unsealed appearance deteriorates.

  The lid material of the present invention is excellent in easy peelability and can be manufactured at low cost, so it can be used as a wide variety of easy-open packaging materials, and particularly preferably used as a lid material for sealing polyethylene containers. Can do.

  The polyethylene container to be bonded to the lid material of the present invention is only required to have at least an adhesion surface with the lid material, and has a barrier property material such as vinylidene chloride, ethylene-vinyl alcohol copolymer, or aluminum during the construction. May be used. Further, it may be a paper container formed by molding a paperboard laminated with polyethylene.

  The opening strength of the sealed container obtained by heat-sealing the (A) layer of the lid material of the present invention and the polyethylene container at 140 to 170 ° C. with a heat sealer is preferably 5 to 25 N, more preferably 8 to 20 N. is there. The lid material having an opening strength in the above range has both easy peel properties and container sealing properties, and is very preferable as a packaging material.

  The lid material of the present invention is a lid for sealing a wide variety of polyethylene containers such as snack foods, dried foods such as instant noodles, soups, miso, pickles, beverages and other aquatic foods and drinks, medicines such as infusion bags, shampoos and cosmetics. It can be used as a material.

  The lid material of the present invention is very useful as a lid material for sealing a wide variety of polyethylene containers because it has excellent easy peel properties and can be manufactured at low cost.

EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples.
(1) Melt mass flow rate (MFR)
It measured based on JISK6922-1 (1997).
(2) Density The density was measured in accordance with JIS K6922-1 (1997).
(3) Storage elastic modulus E '
The storage elastic modulus E ′ was measured in a tensile mode using a trade name Rheogel E4000 (manufactured by UBM Co., Ltd.). The frequency was set to 10 Hz and measurement was performed in the range of −100 to 200 ° C. to determine the storage elastic modulus.
(4) Formability During extrusion lamination, it was confirmed whether molding failure such as film breakage and large width fluctuation did not occur and a stable laminate film could be obtained.
(5) Opening strength At the opening of a paper cup container (flange portion outer diameter 100 mm) in which polyethylene having a density of 940 kg / m ³ is laminated on the inner surface with a thickness of 30 μm, the laminate obtained in the example / comparative example (A ) Layers were brought into contact with each other and heat-sealed with a desktop cup sealer (Sunny Pack Co., Ltd.). The heat sealing conditions were a temperature of 170 ° C., a pressure of 4.0 MPa / cup, and a time of 0.8 seconds.

After cooling at room temperature, the laminate was peeled from the paper cup container at an angle of 90 degrees using a tensile tester (Tensilon RTE-1210 manufactured by Orientec Co., Ltd.), and the strength of the force required for peeling was measured. The tensile speed was 300 mm / min. The force required for peeling showed a peak immediately after opening, and the strength at this peak was defined as the opening strength.
(6) Opening appearance About the paper cup container opened after heat sealing by the method similar to (5), the state of the peeling surface was visually evaluated. The case where the appearance of the peeled surface was good was marked as ◯, the case where some abnormalities such as stringing were found on the peeled surface were marked as Δ, and the case where abnormal peeling such as large-scale stringing or delamination occurred was marked as x.
(7) Sealing property The paper cup container heat-sealed by the same method as in (5) was submerged in water, and the presence or absence of generation of bubbles from the heat-sealed portion of the laminate obtained in Example / Comparative Example and the paper cup was observed. . If no bubble was generated, it was rated as “Good”.
(8) (A) Breaking strength Fb of layer film
The layer (A) was peeled from the laminate obtained in Example / Comparative Example using ethyl acetate to obtain a film made of polyolefin of the (A) layer. This was formed into a strip shape having a width of 15 mm, and pulled by a tensile tester (trade name Tensilon RTE-1210, manufactured by Orientec Co., Ltd.) under the conditions of a tensile speed of 300 mm / min and a distance between chucks of 40 mm. The strength when the film was broken was defined as the breaking strength Fb.
(9) Delamination strength Fd between layers (A) and (C) after heat sealing at 170 ° C.
Heat-sealing the polyethylene layer of an extruded laminate film composed of a low-density polyethylene layer having a thickness of 25 μm and a polyethylene terephthalate (PET) layer having a thickness of 12 μm and the layer (A) of the laminate obtained in Examples / Comparative Examples at 170 ° C. for 1 second. did. This was formed into a 15 mm wide strip and pulled by a tensile testing machine (trade name Tensilon RTE-1210 manufactured by Orientec Co., Ltd.) under the conditions of a tensile speed of 300 mm / min and a distance between chucks of 40 mm. C) The steady value of the delamination strength of the layer was defined as Fd.

Example of production of polyolefin (A-1) to (A-7) in layer (A) The polyolefin in layer (A) was prepared by drying the polyethylene described in Table 1 at the blending ratio in Table 2 except for (A-6). Using a single-screw extruder (made by Plako Co., Ltd.) having a 40 mmφ screw and a strand die, they are blended and extruded into a strand shape at a set temperature of 180 ° C. and a discharge rate of 18 kg / hour. A strand cutter (Seiwa Iron Works Co., Ltd.) Made into a pellet. Table 2 shows the MFR and density of these polyolefins. In (A-6), no processing was performed.

Example 1
A film obtained by pasting together a 12 μm thick polyester film (PET) and a 7 μm thick aluminum foil by a dry laminating method is used as the base material (C), and the following composition is prepared on the aluminum foil side of the base material (C). After applying the adhesive (B-1), a 90 mmφ extrusion laminator (manufactured by Musashinokikai Co., Ltd.) under the conditions of a processing speed of 120 m / min, an air gap length of 130 mm, a cylinder temperature of 340 ° C., and a die temperature of 335 ° C. ) Layer was extrusion laminated to obtain a laminate.

As the polyolefin of the (A) layer, (A-1) having a density of 921 kg / m ³ and MFR of ³⁰ g / 10 min was used. The thickness of the (A) layer was 20 μm.

  The obtained laminate was evaluated for formability, opening strength, opening appearance, sealing property, breaking strength Fb and peeling strength Fd. The results are shown in Table 4.

Adhesive (B-1):
Polyester-based polyurethane resin (trade name: Nipponporan 3228, manufactured by Tosoh Corporation) and polyisocyanate (product name: Coronate L, manufactured by Tosoh Corporation) are mixed at a weight ratio of 10/1, and the solid content concentration is adjusted using ethyl acetate. Diluted to 7%.

Example 2
A laminate was prepared and evaluated in the same manner as in Example 1 except that (A-2) having a density of 925 kg / m ³ and MFR of 26 g / 10 min was used as the polyolefin of the (A) layer. The results are shown in Table 4.

Example 3
A laminate was prepared and evaluated in the same manner as in Example 1 except that (A-3) (A-3) having a density of 930 kg / m ³ and MFR of 27 g / 10 min was used as the polyolefin of the layer (A). The results are shown in Table 4.

Example 4
A laminate was prepared and evaluated in the same manner as in Example 1 except that (A) having a density of 934 kg / m ³ and MFR of 24 g / 10 min was used as the polyolefin of the (A) layer. The results are shown in Table 4.

Example 5
A laminate was prepared and evaluated in the same manner as in Example 1 except that (A) layer (A-5) having a density of 924 kg / m ³ and MFR 60 g / 10 min was used as the polyolefin of the layer. The results are shown in Table 4.

Example 6
(A) A laminate was prepared and evaluated in the same manner as in Example 2 except that the layer thickness was 30 μm. The results are shown in Table 4.

Example 7
A laminate was prepared and evaluated in the same manner as in Example 2 except that (B-2) prepared with the formulation shown below was used as the adhesive for the (B) layer. The results are shown in Table 4.

Adhesive (B-2):
Polyester-based polyurethane resin (manufactured by Tosoh Corporation, trade name: Nipponporan 3228) and polyisocyanate (manufactured by Tosoh Corporation, trade name: Coronate HL) are mixed at a weight ratio of 100/5, and the solid content concentration is adjusted using ethyl acetate. Diluted to 7%.

Comparative Example 1
A laminate was prepared and evaluated in the same manner as in Example 1 except that (A) having a density of 918 kg / m ³ and an MFR of 8 g / 10 min was used as the (A) layer polyolefin. The results are shown in Table 5. Opening strength is high and easy peelability is poor.

Comparative Example 2
A laminate was prepared and evaluated in the same manner as in Example 1 except that (A) layer used was (A-7) having a density of 941 kg / m ³ and MFR of 27 g / 10 min. The results are shown in Table 5. Delamination occurred at the outer edge of the seal part, and the unsealed appearance was poor.

Comparative Example 3
(A) A laminate was prepared and evaluated in the same manner as in Example 2 except that the thickness of the layer was 40 μm. The results are shown in Table 5. Opening strength is high and easy peelability is poor. Further, delamination occurred at the outer edge of the seal part, and the unsealed appearance was inferior.

Comparative Example 4
(A) A laminate was prepared and evaluated in the same manner as in Example 2 except that the thickness of the layer was changed to 5 μm. The results are shown in Table 5. The sealing property of the container in which the laminate was heat-sealed was inferior.

Claims (7)

At least the (A) layer, the (B) layer, and the (C) layer are composed of three layers in this order, the (A) layer is a polyolefin that satisfies the following requirements (a) and (b), the (B) layer is an adhesive, ( (C) The layer is made of at least one base material including an aluminum foil, the film thickness of the (A) layer is 10 to 30 μm, and the surface of the (C) layer in contact with the (B) layer is an aluminum foil. Easy peel lid material for polyethylene containers.
(A) The density measured based on JIS K6922-1 is 921-940 kg / m ³
(B) The melt mass flow rate (MFR) measured based on JIS K6922-1 is 10 to 100 g / 10 min. The easy peel lid | cover material for polyethylene containers of Claim 1 which satisfy | fills the following requirements (c) and (d).
(C) The breaking strength Fb of the film made of polyolefin of the (A) layer is 1 to 4 N / 15 mm width.
(D) The delamination strength Fd (unit: N / 15 mm width) of the (A) layer and the (C) layer after heat sealing at 170 ° C. for 1 second satisfies the following relationship.
Fd × 0.8> Fb The polyolefin of the layer (A) is a high density polyethylene (1) and / or a total of 0 to 90 weights of a copolymer (2) of ethylene having a density of less than 940 kg / m ³ and an α-olefin having 4 or more carbon atoms. And high-pressure low-density polyethylene (3) in an amount of 10 to 100 parts by weight (total of (1), (2) and (3) is 100 parts by weight). The easy-peel lid material for polyethylene containers in any one of 2. The polyolefin of the layer (A) is a high density polyethylene (1) and / or a total of 0 to 40 weights of a copolymer (2) of ethylene having a density of less than 940 kg / m ³ and an α-olefin having 4 or more carbon atoms. 20 to 90 parts by weight of a high pressure method low density polyethylene (3a) having an MFR of 20 g / 10 min or more, and 5 to 40 parts by weight of a high pressure method low density polyethylene (3b) having an MFR of 5 g / 10 min or less, ((1 ), (2), (3a) and (3b) is a composition comprising 100 parts by weight). The easy peel lid for a polyethylene container according to any one of claims 1 to 3.   The easy peel lid for a polyethylene container according to any one of claims 1 to 4, wherein the adhesive of the layer (B) is a polyurethane adhesive or a polybutadiene adhesive. 6. The adhesive for the layer (B) has a storage elastic modulus E ′ at 20 ° C. of 1.0 × 10 ^{6 to} 2.5 × 10 ⁸ Pa. Easy peel lid for polyethylene containers. The opening strength of the sealed container obtained by heat-sealing a polyethylene container having a density of 900 to 970 kg / m ³ based on the layer (A) and JIS K6922-1 at 140 to 170 ° C. is 5 to 5. It is 25N, The easy peel lid | cover material for polyethylene containers in any one of Claim 1 thru | or 6 characterized by the above-mentioned.