JP2018127556A - Resin composition, lid material for easily-openable container, and easily-openable container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin composition capable of forming a seal layer which is excellent in high-speed moldability at the time of extrusion laminate molding, has easy openability due to cohesion detachment, has a sufficiently high heat seal strength and is excellent in easy openability and peeling appearance.SOLUTION: A resin composition contains the following components (A) to (D), and preferably contains 3-55 mass% of the component (A), 3-50 mass% of the component (B), 25-75 mass% of the component (C), and 10-45 mass% of the component (D) with respect to 100 mass% of the total of the components. Component (A): a polyethylene resin; component (B): a propylene polymer having a branch structure in the molecule; component (C): a polypropylene resin other than the component (B); and component (D): an ethylene-α-olefin copolymer.SELECTED DRAWING: None

Description

The present invention is excellent in high-speed moldability at the time of extrusion lamination molding, has an easy-open property by cohesive peeling, has a sufficiently high heat seal strength, and can form a seal layer excellent in easy-open property, peel appearance, etc. It is related with the resin composition which can be performed.
The present invention also relates to a lid for an easy-open container and an easy-open container having a seal layer formed from the resin composition.

  Conventionally, as a packaging method for foods, beverages, medicines, cosmetics, medical instruments, etc., in a container body molded in a tray shape or cup shape with a resin such as polyethylene resin or polypropylene resin, polyester resin, polycarbonate resin, etc. A method of putting an article to be packaged and bringing a lid material into contact with the opening of the container body and sealing it by heat sealing is widely used. In such a package, since it is necessary to peel off the lid when taking out the package, in addition to no leakage of the package from the container, when taking out the package In addition, it is necessary to have a heat seal strength that allows the lid material to be easily peeled off from the container body, that is, to be easily openable.

  In general, there are mainly three types of sealants (sealing materials) used for easy-open lid materials: interfacial peeling type, delamination type, and cohesive peeling type.

  The interfacial peeling type generally maintains a sealed state by adhesion to the adherend, so there is a large variation in sealing performance due to the ambient temperature, and it does not maintain the sealed state due to thermal fusion with the adherend. , There is a drawback of puncture (content leaks) when an impact is applied.

  The delamination-type lid material is composed of a seal layer, a holding layer, and a base material, and the seal layer is formed of the same kind of resin as the adherend (the lid attachment portion of the container), A strong sealing state is maintained by heat sealing, and the holding layer is formed of a resin different from that of the sealing layer and is easily peeled between the sealing layer and the holding layer to provide easy opening.

  However, in the case of delamination type sealant, a part of the sealant remains on the container body side at the time of opening or a film residue occurs at the time of opening. Therefore, the cohesive peeling type sealant is advantageous in that there is no such problem. It is.

  The cohesive peeling type is the same as the delamination type in that it is formed of a sealing layer, a holding layer provided as necessary, and a substrate, but the sealing layer is made of the same kind of resin and holding layer or substrate as the adherend. It is formed of a polymer blend of two kinds of resins of the same kind as the material. Thereby, at the time of heat sealing, the sealing layer is partially heat-sealed with the adherend, and at the time of peeling, the sealing layer is peeled off while cohesively destroying the sealing layer itself at the interface of the polymer blended resin. Therefore, the sealing layer has both functions of sealing properties and peelability.

Such a cover for a cohesive peel type easy-open container is usually produced by extrusion laminating a resin composition of a seal layer to a holding layer or a substrate provided as necessary. .
In addition to extrusion laminate molding, it can be molded by inflation molding or cast molding, but extrusion laminate molding is superior in high-speed moldability compared to other film moldings, so it is preferable from the viewpoint of film productivity. It is.

  Conventionally, as a resin composition for forming a seal layer of a lid for an easily openable container, one containing a polyethylene resin, a polypropylene resin, and an ethylene / α-olefin copolymer has been proposed (for example, Patent Document 1). , 2).

JP2012-184392A JP 2009-7575 A

  The resin composition for forming the sealing layer of the cohesive peeling type easy-opening container lid material is excellent in high-speed moldability at the time of extrusion lamination molding, in addition to having an easy-opening property by cohesive peeling, and It is required that a heat-sealing strength is sufficiently high and a sealing layer excellent in easy-opening property, peeled appearance and the like can be formed.

  However, conventionally, a resin composition that satisfies all of the required characteristics has not been provided. For example, in the resin compositions of Patent Documents 1 and 2, high-speed molding is particularly difficult at the time of extrusion lamination molding. Further improvements are desired for the formulation of the composition and its composition.

The present invention is excellent in high-speed moldability at the time of extrusion lamination molding, has an easy-open property by cohesive peeling, has a sufficiently high heat seal strength, and can form a seal layer excellent in easy-open property, peel appearance, etc. It aims at providing the resin composition which can be performed.
Another object of the present invention is to provide a lid for an easy-open container and an easy-open container having a seal layer formed from the resin composition.

As a result of intensive studies to solve the above problems, the present inventors have found that a polyethylene resin, a propylene polymer having a branched structure in the molecule, and a polypropylene resin different from the propylene polymer. And an ethylene / α-olefin copolymer are excellent in high-speed moldability at the time of extrusion lamination molding, have easy-opening properties by cohesive peeling, have sufficiently high heat seal strength, and easy-openability The present invention was completed by finding that a sealing layer excellent in peeling appearance and the like can be formed.
That is, the gist of the present invention is as follows.

[1] A resin composition comprising the following components (A) to (D).
Component (A): Polyethylene resin component (B): Propylene polymer component having a branched structure in the molecule (C): Polypropylene resin component other than component (B) (D): Ethylene / α-olefin copolymer Coalescence

[2] 3 to 55% by mass of component (A), 3 to 50% by mass of component (B), and 25 to 75 of component (C) with respect to 100% by mass in total of components (A) to (D). The resin composition according to [1], including 10% by mass and 10% to 45% by mass of component (D).

[3] The resin composition according to [1] or [2], wherein the density of the component (A) is 0.910 g / cm ³ or more and less than 0.930 g / cm ³ .

[4] The resin composition according to any one of [1] to [3], wherein the component (B) has a melt flow rate (JIS K7210 (230 ° C., load 2.16 kg)) of 1 to 110 g / 10 minutes. .

[5] The resin composition according to any one of [1] to [4], wherein the melt tension of the component (B) is 15 cN or more.

[6] The resin composition according to any one of [1] to [5], which is a resin composition for extrusion laminate molding.

[7] An easily openable container lid member having a seal layer formed of the resin composition according to any one of [1] to [6].

[8] A polypropylene-based resin layer laminate including a layer made of the resin composition according to any one of [1] to [6].

[9] An easily openable container comprising the easily openable container lid material according to [7] and a container main body made of polypropylene resin.

The resin composition of the present invention is excellent in high-speed moldability at the time of extrusion lamination molding, has an easy-opening property by cohesive peeling, has a sufficiently high heat seal strength, an easy-opening property, an excellent peel appearance, etc. Can be formed.
Therefore, according to the present invention, this resin composition has an easy-opening property by cohesive peeling, and has an easy-opening property that has a sufficiently high heat seal strength and an easy-opening property, an excellent peel appearance, and the like. The container lid can be manufactured with high productivity by high-speed extrusion lamination molding, and an easy-open container having a high commercial value can be manufactured using this easy-open container lid.

The present invention will be described in detail below, but the following description is an example of an embodiment of the present invention, and the present invention is not limited to the following description unless it exceeds the gist. The present invention can be arbitrarily modified and implemented without departing from the scope of the invention.
In addition, in this invention, when expressing by putting a numerical value or a physical-property value before and behind using "-", it shall use as what includes the value before and behind.

  In the present invention, the melt flow rate (MFR) and density of the resin are values measured as follows.

<MFR>
The MFR of the propylene polymer of component (B) and the polypropylene resin of component (C) is measured in accordance with JIS K7210 under conditions of a temperature of 230 ° C., a load of 2.16 kg, and 10 minutes. The MFR of the polyethylene resin of component (A) and the ethylene / α-olefin copolymer of component (D) is measured under the conditions of a temperature of 190 ° C., a load of 2.16 kg, and 10 minutes in accordance with JIS K7210.

<Density>
It is measured by an underwater substitution method according to JIS K7112.

(Resin composition)
The resin composition of the present invention includes the following components (A) to (D).
Component (A): Polyethylene resin component (B): Propylene polymer component having a branched structure in the molecule (C): Polypropylene resin component other than component (B) (D): Ethylene / α-olefin copolymer Coalescence

[Component (A)]
The component (A) contained in the resin composition of the present invention is a polyethylene resin. A polyethylene resin suitable for the present invention is an ethylene homopolymer having an MFR (190 ° C., load 2.16 kg) of 0.05 to 50 g / 10 min and a density of 0.850 to 0.950 g / cm ³ .

  Specific examples of the polyethylene resin include low density polyethylene (LDPE), high density polyethylene (HDPE), medium density polyethylene (MDPE), linear low density polyethylene (LLDPE), and very low density polyethylene (VLDPE). It is done.

Of these, low-density polyethylene is preferred as the polyethylene resin of component (A). In particular, the high-pressure low-density polyethylene is effective for improving the stability of molding processability and the stability of peel strength and improving the peel appearance. The low density polyethylene preferably has a density of 0.880 to 0.930 g / cm ³ , particularly preferably 0.910 g / cm ³ or more and less than 0.930 g / cm ³ .

  These components (A) may use only 1 type, and may mix and use 2 or more types of things from which a physical property differs.

  In the resin composition of the present invention, the content of the component (A) is preferably 100% by mass with respect to the total of 100% by mass of the component (A) and the components (B), (C) and (D) described later. It is 3-55 mass%, More preferably, it is 5-25 mass%. Component (A) is a component that contributes to the suppression of neck-in at the time of film formation by extrusion lamination due to the effect of improving the melt elasticity of the entire composition by blending this, and the content of component (A) is the above lower limit. If the amount is less, the neck-in becomes large and it is difficult to obtain a film having a desired width. If the amount is more than the upper limit, the drawdown property, which is an index of high-speed formability during extrusion lamination molding, tends to deteriorate. From the above viewpoint, the content of the component (A) is more preferably with respect to the total of 100% by mass of the above-described component (A) and the later-described component (B), component (C), and component (D). It is 7% by mass or more, and more preferably 20% by mass or less.

[Component (B)]
The propylene-based polymer having a branched structure in the molecule of the component (B) contained in the resin composition of the present invention is not particularly limited as long as it has a structure in which a polypropylene chain is branched. What is included is also included in the branched structure. In addition, this propylene polymer is usually called a high melt tension polypropylene, and is a material in which the rheological properties of conventional linear polypropylene are improved. Extrusion in the presence of electron beam irradiation or peroxide and a crosslinking monomer. This is a polypropylene-based resin that has a branched structure (including a crosslinked structure) in the molecule by modifying it in the machine or adding a branched structure during polymerization using a special catalyst.

  As the high melt tension polypropylene, for example, JP 2009-275207 A discloses a propylene polymer having a structure in which propylene chains are branched. JP-A-2015-521684 discloses a propylene-based polymer having a crosslinked structure.

  The MFR (230 ° C., load 2.16 kg) of the component (B) is preferably 0.01 to 200 g / 10 minutes, preferably 0.05 to 150 g / 10 minutes, and 0.1 to 120 g / 10 minutes is more preferable, and 1-110 g / 10 minutes is particularly preferable. When the MFR of the propylene-based polymer having a branched structure of the component (B) is not less than the above lower limit, it is easy to uniformly disperse in the production stage of the resin composition, and a good peeling appearance is obtained at the time of peeling, which is not more than the above upper limit. And the original melt tension characteristic of a component (B) can be ensured, and the resin composition which is excellent in the high-speed moldability at the time of extrusion lamination molding can be obtained.

  It is preferable that the component (B) has a melt tension of 10 cN or more, particularly 13 cN or more, particularly 15 cN or more, and exhibits strain hardening.

  Here, “strain hardening” is a phenomenon in which the viscosity increases as the stretch strain of the melt increases, and whether or not “strain hardening” is exhibited in the present invention is measured under the conditions described later. It is determined from the fracture behavior of the molten strand at the time. That is, when the take-up speed of the molten strand is increased, the melt tension is increased and the time when cutting is exhibited is strain hardening.

  Here, the melt tension is equipped with an attachment for measuring the melt tension, and is 190 ° C. using a capilograph (manufactured by Toyo Seiki Seisakusho) having a φ10 mm cylinder with an orifice of φ1 mm and a length of 10 mm at the tip. When the piston descends at a rate of 10 mm / min, the strand discharged from the die is applied to a pulley with a load cell 350 mm below and taken up at a speed of 1 m / min. After stabilization, the take-up speed is 200 m / min in 4 minutes. The load applied to the pulley with the load cell when the strand breaks is referred to as the melt tension. However, when the melt tension of the component (B) is extremely high, the resin may be broken at a take-up speed of 4.0 m / min. In such a case, the tension at the highest speed at which take-up is possible. Is melt tension. In addition, the melt tension of a component (B) is so preferable that it is high, and there is no restriction | limiting in particular in the upper limit.

  A commercial item can also be used as a component (B), for example, "Daploy WB140HMS" by a Borealis company, "WAYMAX MFX3" by Nippon Polypro, etc. can be illustrated.

  These components (B) may be used alone or in combination of two or more of those having different physical properties and structures.

  In the resin composition of the present invention, the content of the component (B) is preferably based on 100% by mass in total of the component (A) and the component (B) described above, the component (C) and the component (D) described later. Is 3 to 50% by mass, more preferably 5 to 20% by mass. Component (B) is a component that contributes to improving the high-speed moldability during extrusion lamination molding by improving the melt tension of the entire composition by blending this, and the content of component (B) is lower than the above lower limit. When the amount is small, this effect becomes insufficient. When the amount is more than the above upper limit, the elasticity of the entire resin composition becomes too high and the drawdown property tends to deteriorate. From the above viewpoint, the content of the component (B) is more preferably based on the total of 100% by mass of the above-described component (A) and component (B), and the later-described component (C) and component (D). It is 7 mass% or more, More preferably, it is 18 mass% or less.

[Component (C)]
The component (C) is a polypropylene resin other than the component (B), and a general thermoplastic polypropylene resin can be used. Examples of the component (C) polypropylene resin include propylene homopolymer, propylene / ethylene random copolymer, propylene / ethylene block copolymer, propylene / α-olefin random copolymer, propylene / α-olefin block copolymer. Examples thereof include a polymer, a propylene / ethylene / α-olefin random copolymer, and a propylene / ethylene / α-olefin random copolymer. Examples of the α-olefin used as a comonomer include 1-butene, 1-pentene, 3-methyl-1-butene, 1-hexene, 4-methyl-1-pentene, 3-methyl-1-pentene, and 1-heptene. , 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicocene and the like, and α-olefins having about 4 to 20 carbon atoms. The α-olefin used as a comonomer may be one type, or two or more types may be used in combination.

  The content of propylene units in the component (C) polypropylene resin is preferably 80% by mass or more, and more preferably 85% by mass or more. It is preferable in terms of heat resistance that the content of the propylene unit is not less than the above lower limit.

  The polypropylene resin of component (C) is produced by a known method. For example, it is produced by a known method such as a batch method, a gas phase method, or a slurry method using a catalyst such as a Ziegler-Natta catalyst or a metallocene catalyst.

  The MFR (230 ° C., load 2.16 kg) of the polypropylene resin of the component (C) is not particularly limited, but is preferably 1 to 100 g / 10 minutes, and more preferably 10 to 50 g / 10 minutes. . When the MFR of the polypropylene resin of component (C) is below the above upper limit, heat resistance, mechanical strength, etc. tend to be good, and when it is above the above lower limit, extrusion laminate moldability is good. Tend to be.

  As the component (C), the polypropylene-based resin may be used alone, or two or more types having different copolymer component compositions and physical properties may be mixed and used.

  In the resin composition of the present invention, the content of the component (C) is preferably based on 100% by mass of the total of the component (A), the component (B) and the component (C) described above and the component (D) described later. Is 25-75 mass%. Component (C) is a component that contributes to the mechanical strength, heat resistance, and stretchability of the layer comprising the resin composition of the present invention. When the content of component (C) is less than the above lower limit, these characteristics However, if it is too much, the content of other components will be relatively low, the heat seal strength will be too high, the easy-openability will be impaired, and the high-speed extrusion laminate moldability will be improved. The effect is impaired. From the above viewpoint, the content of the component (C) is more preferably based on 100% by mass of the total of the above-described component (A), component (B) and component (C), and the component (D) described later. It is 30 mass% or more, More preferably, it is 70 mass% or less.

[Component (D)]
The ethylene / α-olefin copolymer of component (D) is a component for imparting easy peelability to the resin composition of the present invention and improving the peel appearance.

  The α-olefin constituting the ethylene / α-olefin copolymer of component (D) is not limited, and specific examples include propylene, 1-butene, 3-methyl-1-butene, 1-pentene, 4 -1 type, or 2 or more types, such as -methyl-1-pentene, 1-hexene, 1-octene, 1-decene, is mentioned. Among these, α-olefins having 3 to 8 carbon atoms are preferable.

The ethylene / α-olefin copolymer of component (D) contains ethylene units and α-olefin units in a weight ratio of [ethylene units]: [α-olefin units] = 60: 40 to 90:10. It is preferable that That is, when the total of the ethylene unit content and the α-olefin unit content is 100% by mass, the ethylene unit content is 60 to 90% by mass and the α-olefin unit content is 10 to 40%. It is preferable that it is mass%. The copolymerization ratio of ethylene and α-olefin in the ethylene / α-olefin copolymer of component (D) is more preferably 100% by mass of the total of ethylene unit content and α-olefin unit content. The content of ethylene units is 70 to 80% by mass, and the content of α-olefin units is 20 to 30% by mass.
When the content of the ethylene unit is within the above range, the affinity with other components is good and the fine dispersibility of the resin composition tends to be improved.

  The ethylene / α-olefin copolymer of component (D) may contain other monomer units other than ethylene and the α-olefin. The content in the case of containing these other monomer units is not limited, but the total content of the other monomer units and the α-olefin unit is within the range of the content of the α-olefin unit. It is preferable to be within. Specific examples of other monomers include vinyl esters (such as vinyl acetate), unsaturated carboxylic acids or esters thereof (such as acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, and ethyl acrylate). Can be used.

The MFR (190 ° C., load 2.16 kg) of the ethylene / α-olefin copolymer of component (D) is not limited, but is preferably 0.5 to 50 g / 10 minutes, and 1 to 40 g / 10 minutes. More preferably.
When melt-kneading with other resins when the MFR is not less than the above lower limit, there is no generation of foreign matter due to insufficient kneading, and it is easy to obtain a resin composition having a good appearance when molded, and if not more than the above upper limit, The component (D) is preferable because the fine dispersibility is maintained without orientation.

The density of the ethylene / α-olefin copolymer is not limited, but is usually 0.910 g / cm ³ or less, preferably 0.900 g / cm ³ or less. When the density of the ethylene / α-olefin copolymer is not more than the above upper limit, the strain relaxation effect at the time of molding tends to be sufficient, and the interlayer adhesive strength tends to be improved. The lower limit of the density of the ethylene / α-olefin copolymer is not limited, but is usually 0.85 g / cm ³ or more.

  Commercially available products may be used as the ethylene / α-olefin copolymer suitable for the present invention, such as “Tuffmer (registered trademark)” series manufactured by Mitsui Chemicals, Inc. “engage (registered trademark)” series, etc. Those corresponding to the above characteristics can be selected as appropriate.

  These components (D) may use only 1 type, and may mix and use 2 or more types from which content, physical properties, etc. of an ethylene unit differ.

  In the resin composition of the present invention, the content of the component (D) is preferably 10 with respect to the aforementioned component (A), the component (B), and the total of 100% by mass of the component (C) and the component (D). It is -45 mass%. Component (D) is a component that exhibits the effect of improving mechanical strength and peel appearance. However, if the content is too small, the above effect cannot be obtained sufficiently, and if it is too much, the entire resin composition is obtained. The heat resistance of the will decrease. From the above viewpoint, the content of the component (D) is more preferably 15% by mass with respect to 100% by mass of the total of the component (A), the component (B) and the component (C) and the component (D). % Or more, and more preferably 40% by mass or less.

[Other ingredients]
In the resin composition of the present invention, in addition to the above-described components, other optional additives and resins, etc. (hereinafter referred to as “other components”) according to various purposes within a range not significantly impairing the effects of the present invention. Can be blended. Other components may be used alone or in combination of two or more in any combination and ratio.

  As additives, auxiliary additives generally used for polyolefins, specifically, process oils, neutralizers, processing aids, plasticizers, crystal nucleating agents, impact modifiers, flame retardants, flame retardant aids , Crosslinking agents, crosslinking aids, antistatic agents, lubricants, fillers, compatibilizers, heat stabilizers, weathering stabilizers (antioxidants, light stabilizers, UV absorbers, etc.), antifogging agents, slip agents, Antiblocking agents, antibacterial agents, carbon black, colorants (pigments, dyes, etc.) and the like can be mentioned.

  Of these, flame retardants are broadly classified into halogen-based flame retardants and non-halogen-based flame retardants. Non-halogen-based flame retardants are preferred, specifically, metal hydroxides, phosphorus-based flame retardants, and nitrogen-containing compounds. (Melamine type, guanidine type) flame retardant and inorganic type compound (borate, molybdenum compound) flame retardant and the like.

  Examples of the heat stabilizer and the antioxidant include hindered phenols, phosphorus compounds, hindered amines, sulfur compounds, copper compounds, alkali metal halides, and the like.

  Fillers are roughly classified into organic fillers and inorganic fillers. Examples of the organic filler include naturally occurring polymers such as starch, cellulose fine particles, wood flour, okara, fir husk, bran, and modified products thereof. Inorganic fillers include talc, calcium carbonate, zinc carbonate, wollastonite, silica, alumina, magnesium oxide, calcium silicate, sodium aluminate, calcium aluminate, sodium aluminosilicate, magnesium silicate, glass balloon, carbon Examples thereof include black, zinc oxide, antimony trioxide, zeolite, metal fiber, metal whisker, ceramic whisker, potassium titanate, boron nitride, graphite, and carbon fiber.

  When these additives are used, the content thereof is not limited, but the content in the resin composition of the present invention is usually 0.01% by mass or more, preferably 0.1% by mass or more, and usually It is desirable that the content be 5% by mass or less, preferably 2% by mass or less. In addition, when using the resin composition of this invention as a masterbatch, these additives can also be contained in the density | concentration of 2-50 times as described above, Preferably it is 3-30 times.

  Specific examples of resins used as other components include polyphenylene ether resins; polycarbonate resins; polyamide resins such as nylon 66 and nylon 11; polyester resins such as polyethylene terephthalate and polybutylene terephthalate; and styrene resins such as polystyrene. Examples thereof include resins and acrylic / methacrylic resins such as polymethyl methacrylate resins.

  When the resin composition of this invention contains these other resin, the content is 30 with respect to a total of 100 mass parts of a component (A), a component (B), a component (C), and a component (D). It is preferable that it is below mass parts.

[Production method]
Using the component (A), the component (B), the component (C) and the component (D), and other components added as necessary, the blending method for producing the resin composition of the present invention is as follows. There are a melting method, a solution method, a suspension dispersion method, etc., and there is no particular limitation. Practically, the melt kneading method is preferable.

  Specific methods for melt-kneading include powdered or granular components (A) to (D) and other components added as necessary at a predetermined blending ratio, Henschel mixer, ribbon Examples of the method include uniform mixing using a blender, a V-type blender, and the like, and then kneading using an ordinary kneader such as a Banbury mixer, a kneader, a roll, a single screw or a twin screw multi-screw extruder.

  The temperature of melt kneading of each component is usually in the range of 100 ° C to 300 ° C, preferably in the range of 120 ° C to 280 ° C, and particularly preferably in the range of 150 ° C to 250 ° C. Furthermore, the kneading order and method of each component are not particularly limited, and a method of kneading the components (A) to (D) and other components used as necessary, or a component (A ) To (D) and a part of other components used as necessary may be kneaded in advance, and then the remaining components may be kneaded.

[Film forming]
The resin composition of the present invention can be easily formed as a sealing layer (sealing layer film) by various film forming methods such as extrusion lamination molding, T-die molding, and air-cooled inflation molding.

  In particular, since the resin composition of the present invention is excellent in high-speed moldability during extrusion lamination molding, it is advantageous for forming a seal layer by extrusion lamination molding.

  The thickness of the sealing layer film is usually 2 to 100 μm, and preferably 5 to 30 μm. When the thickness of the sealing layer is within the above range, in view of obtaining sufficient heat-sealing strength, in view of obtaining cohesive peelability, in application to an easy-opening lid of an easy-open container, the thickness of the lid Is preferable from the viewpoint of setting the value to an appropriate range.

[Easily openable lid material, easy openable container]
The seal layer or the film for a seal layer formed by the resin composition of the present invention is useful as a seal layer for a lid for an easily openable container. Moreover, this easy-open lid | cover material is the lid | cover for easy-open containers of an easily openable container by carrying out the lamination | stacking integration of the sealing layer or film for sealing layers which consists of the resin composition of this invention normally with a base material. It can be suitably used as a material. In this case, the thickness of the sealing layer or the sealing layer film is usually 2 to 100 μm, and preferably 5 to 30 μm. If the thickness of the seal layer or the film for the seal layer is too thin, sufficient heat seal strength cannot be obtained, and the cohesive peelability will be inferior. When the container is applied to an easily openable lid material, the thickness of the lid material is increased, which is not preferable. A polyolefin-based resin layer such as polyethylene or polypropylene can be interposed as a holding layer between the sealing layer film and the substrate. The thickness of the holding layer is usually about 5 to 500 μm, particularly about 10 to 100 μm.

  Examples of the base material of the easy-open lid material include aluminum foil, paper, polyester resin films represented by polyethylene terephthalate, such as stretched polyester film, stretched nylon film, polyethylene, polypropylene, and other olefin resin films, such as stretched polypropylene film. , Polystyrene film, silica-deposited stretched polyester film, aluminum-deposited stretched polyester film, other barrier films, etc. are generally applicable as long as they are used as a base material for flexible packaging materials. A suitable base material can be selected and used.

  Examples of the method for laminating and integrating the sealing layer film made of the resin composition of the present invention on such a substrate include a method of bonding with an adhesive such as polyurethane, polyester, or polyether. Further, the base film and the sealing layer film may be integrally formed by coextrusion lamination.

  In addition, in order to produce a lid member in which a holding layer is interposed between the sealing layer film and the substrate, the resin composition of the present invention is produced by a film molding method such as an inflation method or a T-die method. After laminating and molding a holding layer made of a polyolefin resin such as polyethylene and polypropylene, or by laminating a holding layer and a seal layer by coextrusion lamination molding with a polyolefin resin such as polyethylene and polypropylene, Extrusion lamination of sealing layer and holding layer to a base material layer made of various thermoplastic resins such as aluminum foil, paper, polyester resin typified by polyethylene terephthalate, olefin resin such as polyethylene and polypropylene The method of manufacturing by forming a laminate film by shaping | molding is mentioned.

  The easy-opening lid material made of a laminated film or laminated sheet of the obtained seal layer / base material or seal layer / holding layer / base material is disposed in the opening portions of various containers and along the flange portions of the opening portions. It can be used for sealing a container by heat-pressing and heat-sealing.

  The heat sealing conditions at this time are as follows. The melting point or the melting point of the component (B) is about 20 ° C., for example, about 140 to 200 ° C. It is preferable that the heat sealing time is about 1 to 10 seconds.

  In addition, as a constituent material of a container body of an easy-open container to which an easy-open lid using the resin composition of the present invention is applied, a polyethylene resin, a polypropylene resin, a polyethylene terephthalate resin, a polystyrene resin, a polycarbonate resin, These blend materials etc. are mentioned, Among these, it is preferable that a container main body consists of polypropylene resin.

  The easy-open lid having a seal layer formed from the resin composition of the present invention and the easy-open container having the easy-open lid are suitable for any application that requires easy-openability of the lid. Although it can use suitably, it can be used especially suitably in the container for food-drinks.

[Polypropylene resin layer laminate]
The laminated structure of the polypropylene resin layer laminate of the present invention including the layer made of the resin composition of the present invention is appropriately designed according to its use. That is, when the resin composition of the present invention is expressed as a sealing material, the printing protective layer / printing layer / aluminum foil / sealing material, biaxially oriented polyester layer / printing layer / adhesive / aluminum foil / sealing material, biaxially oriented. Examples of the laminated material having a configuration such as polypropylene layer / printing layer / adhesive / sealing material, printing protective layer / printing layer / paper / sealing material, polyethylene layer / printing layer / paper / polyethylene layer / aluminum foil / sealing material be able to.

  EXAMPLES The present invention will be described more specifically with reference to the following examples and comparative examples. However, the present invention is not limited to the following examples unless it exceeds the gist. The values of various production conditions and evaluation results in the following examples have meanings as preferred values of the upper limit or lower limit in the embodiments of the present invention, and the preferred ranges are the upper limit or lower limit values described above, and It may be a range defined by a combination of values of the examples or values between the examples.

  The MFR and density of each component were measured by the method described above. The melt tension is also measured by the method described above. Also, when measuring the melt tension, when the take-up speed is increased, the take-up load suddenly increases, and when it reaches rupture, it indicates “strain hardenability”, otherwise it does not show strain hardenability. It was. In the case where the strand did not break and “does not show strain hardening”, the load at the point where the load applied to the pulley with the load cell did not increase even when the take-up speed was increased was taken as the melt tension.

[material]
The raw materials used in the following examples and comparative examples are as follows.

<Component (A)>
A-1: Low density polyethylene resin (Density (JIS K7112): 0.919 g / cm ³ , MFR (190 ° C., 2.16 kg (JIS K7210)): 4 g / 10 min)
A-2: Low density polyethylene-based resin (Density (JASTM D1505): 0.922 g / cm ³ , MFR (190 ° C., 2.16 kg (ASTM D1238)): 2 g / 10 min)

<Component (B)>
B-1: Propylene polymer having a branched structure in the molecule (MFR (230 ° C., 2.16 kg (JIS K7210)): 20 g / 10 min, melt tension: 117.5 cN, exhibiting strain hardening)
B-2: Propylene-based polymer having a branched structure in the molecule (MFR (230 ° C., 2.16 kg (JIS K7210)): 60 g / 10 min, melt tension: 40, 4 cN, showing strain hardening)
B-3: Propylene polymer having a branched structure in the molecule (MFR (230 ° C., 2.16 kg (JIS K7210)): 100 g / 10 min, melt tension: 19.7 cN, exhibiting strain hardening)
B-4: Propylene polymer having a branched structure in the molecule (MFR (230 ° C., 2.16 kg (JIS K7210)): 7 g / 10 min, melt tension: 120 cN or more, exhibiting strain hardening)
B-5: Propylene polymer having a branched structure in the molecule (MFR (230 ° C., 2.16 kg (JIS K7210)): 7 g / 10 min, melt tension: 120 cN or more, exhibiting strain hardening)

<Ingredient (C)>
C-1: Polypropylene resin: (Density (JIS K7112): 0.920 g / cm ³ , MFR (230 ° C., 2.16 kg (JIS K7210)): 30 g / 10 min)
C-2: Polypropylene resin: (Density (JIS K7112): 0.920 g / cm ³ , MFR (230 ° C., 2.16 kg (JIS K7210)): 9.5 g / 10 min)
C-3: Polypropylene resin: (Density (JIS K7112): 0.920 g / cm ³ , MFR (230 ° C., 2.16 kg (JIS K7210)): 6.5 g / 10 min)

<Component (D)>
D-1: ethylene / α-olefin copolymer (density (ASTM D1505): 0.893 g / cm ³ , MFR (190 ° C., 2.16 kg (ASTM D1238)): 3.6 g / 10 min, ethylene and 1 -Copolymer with butene, ethylene unit content 82.1% by mass)

[Production of evaluation film]
In order to confirm the difference in extrusion laminate formability and easy-openability (easy peel property), each raw material component was blended at the blending ratios shown in Table-1 and Table-2 with a twin screw extruder “TEX30” (Nippon Steel Co., Ltd.). Made of polyethylene terephthalate film (thickness 12 μm) and polypropylene used as a base material using a “two-kind two-layer test laminator device” (manufactured by Sumitomo Heavy Industries Modern). On the polypropylene film side of the laminated film of the film (thickness 20 μm), extrusion lamination was performed under the following conditions to form a seal layer film having a thickness of about 30 μm, which was used as an evaluation film.
Molding temperature: 280 ° C
Screw rotation speed: 100rpm
Take-off speed: 50 m / min Die lip width: 370 mm

<Extruded laminate moldability>
・ Neck-in (NI)
In the production of the evaluation film, the molding temperature, screw rotation speed, and die lip width were fixed, and the width of the film obtained when molded at a take-up speed of 50 m / min was defined as neck-in (NI). The larger the neck-in value, the wider the effective product width, and the better the extruded film formability.
・ Drawdown (DD)
In the production of the above film for evaluation, when the molding temperature, screw rotation speed and die lip width are fixed and the take-up speed is increased, the molded film cannot follow the formability of the take-up roll, and the film breaks, and the film is formed. The take-off speed in the case where it becomes impossible to draw is defined as drawdown (DD). The larger the drawdown value, the better the extrusion laminate moldability at high speed.

<Peel strength (heat seal strength)>
The evaluation film and the following adherend were cut into a size of 70 mm × 100 mm, and the evaluation film was placed on the adherend so that the sealant film side was in contact therewith. Heat sealing was performed under the following conditions using a heat sealer (manufactured by Sagawa Seisakusho Co., Ltd.), and the central portion in the length direction of the evaluation film was heat sealed to a width of 10 mm.
Pressure: 0.2MPa
Time: 1.0 seconds Seal bar: 10 mm
Temperature: 140 ° C, 150 ° C, 160 ° C, 170 ° C, or 180 ° C
Substrate: Polypropylene film having a thickness of 0.3 mm Thereafter, the heat seal strength is measured by pulling and peeling the non-heat-sealed portion of the evaluation film and the non-heat-sealed portion of the adherend away from each other. did. The heat seal strength is preferably about 4 to 20 N / 15 mm in terms of both easy opening and seal strength.

  The above evaluation results are shown in Table-1 and Table-2.

<Evaluation results>
Table 1 and Table 2 show the following.

  In Examples 1 to 5 corresponding to the resin composition of the present invention, heat seal strength suitable for coexistence of easy-openability and seal strength is achieved, and extrusion laminate moldability, particularly high-speed moldability (DD). It turns out that it is excellent.

  On the other hand, in Comparative Examples 1 to 8 that do not use the component (B), the value of drawdown (DD) is inferior to that of the Examples, and in Comparative Example 9, the component (A) is used. In Comparative Example 10, the component (B) was not used, and a polypropylene resin having a low fluidity was used as the component (C), so that stable film formation could not be performed.

Claims (9)

A resin composition containing the following components (A) to (D).
Component (A): Polyethylene resin component (B): Propylene polymer component having a branched structure in the molecule (C): Polypropylene resin component other than component (B) (D): Ethylene / α-olefin copolymer Coalescence   3 to 55% by mass of component (A), 3 to 50% by mass of component (B), and 25 to 75% by mass of component (C) with respect to 100% by mass in total of components (A) to (D), The resin composition of Claim 1 containing 10-45 mass% of a component (D). The resin composition of Claim 1 or 2 whose density of a component (A) is 0.910 g / cm < ³ > or more and less than 0.930 g / cm < ³ >.   The resin composition according to any one of claims 1 to 3, wherein a melt flow rate (JIS K7210 (230 ° C, load 2.16 kg)) of the component (B) is 1-110 g / 10 min.   The resin composition according to any one of claims 1 to 4, wherein the melt tension of the component (B) is 15 cN or more.   The resin composition according to any one of claims 1 to 5, which is a resin composition for extrusion lamination molding.   An easily openable container lid member having a seal layer formed of the resin composition according to any one of claims 1 to 6.   A polypropylene-based resin layer laminate including a layer made of the resin composition according to any one of claims 1 to 6.   An easy-open container having the lid for an easy-open container according to claim 7 and a container body made of polypropylene resin.