Resin compositions, films, and multilayer films

Abstract

To provide a resin composition, a film and a multilayer film capable of obtaining a film having relatively excellent tear resistance.SOLUTION: There is provided a resin composition which comprises: a propylene-based polymer (1) containing 97 mass% or more of a structural unit derived from propylene; a propylene-based copolymer (2) containing 60 mass% or more and less than 80 mass% of a structural unit derived from propylene and more than 20 mass% and 40 mass% or less of a structural unit derived from at least one selected from the group consisting of ethylene and an α-olefin having 4 to 12 carbon atoms; (3) a propylene-based copolymer containing 80 mass% or more and less than 97 mass% of a structural unit derived from propylene and more than 3 mass% and 20 mass% or less of a structural unit derived from at least one selected from the group consisting of ethylene and an α-olefin having 4 to 12 carbon atoms: and an ethylene-based copolymer containing 75 mass% or more and 95 mass% or less of a structural unit derived from ethylene and 5 mass% or more and 25 mass% or less of a structural unit derived from an α-olefin having 4 to 12 carbon atoms.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a resin composition, a film containing the resin composition, and a multilayer film comprising the film. [Background technology]

[0002] Conventionally, films used in various packaging materials, for example, are known to have a structure in which a polyethylene terephthalate (PET) biaxially oriented film is used as the base film, and a polypropylene (PP) unoriented film is laminated to the base film as a sealant film. A packaging bag is formed by heat-sealing a film with this structure so that the sealant film is on the inside and a storage space is formed.

[0003] Packaging bags formed using sealant film can be used, for example, as retort food packaging bags. In recent years, there has been a demand for sealant films with superior heat-seal strength to enable retort food packaging bags to be used for microwave cooking.

[0004] As a resin composition used in sealant films with excellent heat seal strength, for example, Patent Document 1 describes a propylene-based block copolymer with 70-95% by weight and a density of 890-925 kg / m³. 3 A propylene-based resin composition has been proposed that contains 5 to 30% by weight of an ethylene-α-olefin copolymer with an n-hexane extractable amount of 0.01 to 2.6% by weight. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2006-161033 [Overview of the project] [Problems that the invention aims to solve]

[0006] Incidentally, in recent years, there has been a growing demand for reducing the volume of packaging materials from the perspective of reducing environmental impact, and consequently, there is a need for thinner sealant films. However, when a sealant film formed using the resin composition described in Patent Document 1 is made thinner, there is a problem that the packaging bag is more prone to damage when dropped while containing its contents. In other words, there is room for improvement in terms of tear resistance.

[0007] This invention has been made in view of these circumstances, and aims to provide a resin composition capable of producing a film with relatively excellent tear resistance, a film containing the resin composition, and a multilayer film comprising the film. [Means for solving the problem]

[0008] The resin composition according to the present invention is A propylene polymer (1) containing 97% by mass or more of structural units derived from propylene, A propylene copolymer (2) containing 60% by mass or more and less than 80% by mass of structural units derived from propylene, and more than 20% by mass and 40% by mass or less of structural units derived from at least one selected from the group consisting of ethylene and α-olefins having 4 to 12 carbon atoms, A propylene copolymer (3) comprising 80% by mass or more and less than 97% by mass of structural units derived from propylene, and more than 3% by mass and 20% by mass or less of structural units derived from at least one selected from the group consisting of ethylene and α-olefins having 4 to 12 carbon atoms, An ethylene-based copolymer containing 75% to 95% by mass of structural units derived from ethylene and 5% to 25% by mass of structural units derived from α-olefins having 4 to 12 carbon atoms, Includes.

[0009] The film according to the present invention contains the above-mentioned resin composition.

[0010] The film according to the present invention contains an olefin polymer composition and satisfies the following requirements. Requirements: In the chromatogram obtained by measuring the elution behavior of the components contained in the film under the following measurement conditions using gradient polymer elution chromatography, an elution peak (X) measured at a retention time of 9.40 minutes or more and less than 10.40 minutes, an elution peak (Y) measured at a retention time of 10.40 minutes or more and less than 12.50 minutes, and an elution peak (Z) measured at a retention time of 12.50 minutes or more and 15.50 minutes or less exist, and the retention time at the peak top of the elution peak (Y) is 10.40 minutes or more and 10.80 minutes or less. Measurement conditions: · As a measurement sample, use an orthodichlorobenzene solution in which the film is dissolved at a concentration of 20 mg / 20 mL. · Adjust the temperature of the column to 165°C. · Use butoxyethanol and orthodichlorobenzene as the mobile phase. · From the start of measurement to 2 minutes, flow butoxyethanol into the column at a flow rate of 0.5 mL / min. · From 2 minutes to 10 minutes after the start of measurement, flow butoxyethanol into the column while linearly changing the flow rate from 0.5 mL / min to 0 mL / min, and at the same time, flow orthodichlorobenzene into the column while linearly changing the flow rate from 0 mL / min to 0.5 mL / min. · From 10 minutes to 15 minutes after the start of measurement, flow orthodichlorobenzene into the column at a flow rate of 0.5 mL / min. · From 15 minutes to 25 minutes after the start of measurement, flow butoxyethanol into the column at a flow rate of 0.5 mL / min.

[0011] The multilayer film according to the present invention includes the above film as a sealant layer.

Effects of the Invention

[0012] According to the present invention, it is possible to provide a resin composition that can produce a film with relatively excellent tear resistance, a film containing the resin composition, and a multilayer film comprising the film. [Modes for carrying out the invention]

[0013] The following describes embodiments of the present invention, but the present invention is not limited to the following embodiments.

[0014] <Resin composition> The resin composition according to this embodiment comprises a propylene polymer (1), a propylene copolymer (2), a propylene copolymer (3), and an ethylene copolymer.

[0015] The propylene polymer (1) contains 97% by mass or more of structural units derived from propylene. The content of structural units derived from propylene in the propylene polymer (1) is preferably 99% by mass or more and 100% by mass or less, and more preferably 100% by mass. That is, the propylene polymer (1) may be a propylene homopolymer.

[0016] The propylene polymer (1) may contain structural units derived from ethylene and at least one selected from the group consisting of α-olefins having 4 to 12 carbon atoms. The content of structural units derived from ethylene and at least one selected from the group consisting of α-olefins having 4 to 12 carbon atoms in the propylene polymer (1) is preferably 3% by mass or less, and more preferably 0% by mass or more and 1% by mass or less.

[0017] The propylene copolymer (2) contains 60% by mass or more and less than 80% by mass of structural units derived from propylene, and more than 20% by mass and 40% by mass or less of structural units derived from ethylene and at least one selected from the group consisting of ethylene and α-olefins having 4 to 12 carbon atoms. The propylene copolymer (2) is preferably a propylene-ethylene copolymer.

[0018] The content of structural units derived from propylene in the propylene copolymer (2) is preferably 65% ​​by mass or more and less than 80% by mass, more preferably 70% by mass or more and less than 80% by mass, and even more preferably 70% by mass or more and 75% by mass or less. Furthermore, the content of structural units derived from ethylene and at least one selected from the group consisting of α-olefins having 4 to 12 carbon atoms is preferably more than 20% by mass and 35% by mass or less, more preferably more than 20% by mass and 30% by mass or less, and even more preferably 25% by mass or more and 30% by mass or less.

[0019] Examples of α-olefins having 4 to 12 carbon atoms in the propylene polymer (1) and propylene copolymer (2) include 1-butene, 1-hexene, and 1-octene, with 1-butene being preferred. The structural units derived from the α-olefins having 4 to 12 carbon atoms may be structural units derived from a single α-olefin or structural units derived from two or more α-olefins.

[0020] In one embodiment, the resin composition according to this embodiment is preferably such that the propylene polymer (1) is a propylene homopolymer and the propylene copolymer (2) is a propylene-ethylene copolymer, from the viewpoint of improving the tear resistance of the film.

[0021] Methods for producing propylene polymers (1) and propylene copolymers (2) include polymerizing raw materials such as propylene and ethylene using a Ziegler-Natta catalyst or a metallocene catalyst.

[0022] Polymerization methods for propylene polymers (1) and propylene copolymers (2) include polymerization in an inert solvent such as hexane, heptane, toluene, or xylene; polymerization in liquid propylene or ethylene; polymerization in the gas phase by adding a catalyst to gaseous propylene or ethylene; or polymerization by combining these methods.

[0023] A method for producing a propylene polymer (1) and a propylene copolymer (2) is, from the viewpoint of productivity, preferably, a first step of producing a propylene polymer (1) in the absence of a substantially inert solvent, and then a second step of polymerizing propylene with ethylene and at least one selected from the group consisting of α-olefins having 4 to 12 carbon atoms in the gas phase in the presence of the propylene polymer (1) to produce a propylene copolymer (2), thereby obtaining a propylene multistage polymer. The propylene multistage polymer is a propylene polymer composition containing the propylene polymer (1) component and the propylene copolymer (2) component.

[0024] The propylene-based multistage polymer has a content of propylene-based polymer (1) component of 50 parts by mass or more and 90 parts by mass or less, more preferably 60 parts by mass or more and 90 parts by mass or less, and even more preferably 60 parts by mass or more and 80 parts by mass or less, per 100 parts by mass of the total content of propylene-based polymer (1) component and propylene-based copolymer (2) component. Furthermore, the content of propylene-based polymer (2) component of propylene-based polymer (2) component of 100 parts by mass or more and 50 parts by mass or less, more preferably 10 parts by mass or more and 40 parts by mass or less, and even more preferably 20 parts by mass or more and 40 parts by mass or less, per 100 parts by mass of the total content of propylene-based polymer (1) component and propylene-based copolymer (2) component.

[0025] Methods for adjusting the ethylene content of propylene polymers (1) and propylene copolymers (2) include adding appropriate amounts of molecular weight regulators such as hydrogen gas and metal compounds, and ethylene, at each step of polymerization, and adjusting the temperature and pressure during polymerization.

[0026] The ratio of propylene polymer (1) and propylene copolymer (2) produced can be controlled by the polymerization time in the first and second steps, the size of the polymerization tank, the amount of polymer held in the polymerization tank, the polymerization temperature, the polymerization pressure, etc. If necessary, drying may be performed at a temperature below the melting point of polypropylene in order to remove residual solvent of polypropylene and ultra-low molecular weight oligomers produced as by-products during manufacturing. Examples of drying methods include those described in Japanese Patent Publication No. 55-75410 and Japanese Patent No. 2565753.

[0027] The melt flow rate (MFR) of the propylene-based multistage polymer obtained in the second step, measured at a temperature of 230°C and a load of 2.16 kg, is preferably 0.001 g / 10 min to 10 g / 10 min, more preferably 0.01 g / 10 min to 10 g / 10 min, and even more preferably 0.01 g / 10 min to 5 g / 10 min, from the viewpoint of improving the processability and hygiene of the film. Furthermore, the MFR of a propylene-based polymer composition containing a propylene-based multistage polymer and other components can also be within the same range as that of the propylene-based multistage polymer described above. The MFR is measured by Method A as specified in JIS K7210-1.

[0028] The propylene copolymer (3) contains 80% by mass or more and less than 97% by mass of structural units derived from propylene, and more than 3% by mass and 20% by mass or less of structural units derived from at least one selected from the group consisting of ethylene and α-olefins having 4 to 12 carbon atoms. From the viewpoint of improving the tear resistance and heat seal strength of the film, the propylene copolymer (3) is preferably a propylene-ethylene copolymer.

[0029] The content of structural units derived from propylene in the propylene copolymer (3) is preferably 75% by mass or more and less than 97% by mass, and more preferably 78% by mass or more and less than 97% by mass. Furthermore, the content of structural units derived from ethylene and at least one selected from the group consisting of 4 to 12 carbon atoms in the propylene copolymer (3) is preferably more than 3% by mass and 15% by mass or less, and more preferably more than 3% by mass and 12% by mass or less.

[0030] Examples of α-olefins having 4 to 12 carbon atoms include 1-butene, 1-hexene, and 1-octene, with 1-butene being preferred. The structural units derived from α-olefins having 4 to 12 carbon atoms may be structural units derived from a single α-olefin or structural units derived from two or more α-olefins.

[0031] The propylene copolymer (3) may be produced using a heterogeneous catalyst or a homogeneous catalyst (for example, a metallocene catalyst).

[0032] The melt flow rate (MFR) of the propylene copolymer (3), measured at a temperature of 230°C and a load of 2.16 kg, is preferably 1 g / 10 min to 10 g / 10 min, more preferably 1 g / 10 min to 8 g / 10 min, and even more preferably 2 g / 10 min to 5 g / 10 min. The MFR is measured by Method A as specified in JIS K7210-1.

[0033] Furthermore, the melting point of the propylene copolymer (3), as measured by differential scanning calorimetry (DSC), is preferably 120°C to 165°C, more preferably 120°C to 150°C, and even more preferably 125°C to 150°C.

[0034] The density of the propylene copolymer (3) is preferably 850 kg / m³. 3 More than 910kg / m 3 The following, and more preferably 860 kg / m³3 910 kg / m or less, more preferably 860 kg / m 3 or more and 900 kg / m or less. The density of the propylene-based copolymer (3) is measured according to the method specified in Method A of JIS K7112-1980, and the sample is annealed as described in JIS K6760-1995. 3 910 kg / m or less, more preferably 860 kg / m 3 or more and 900 kg / m or less. The density of the propylene-based copolymer (3) is measured according to the method specified in Method A of JIS K7112-1980, and the sample is annealed as described in JIS K6760-1995.

[0035] The ethylene-based copolymer contains 75% by mass or more and 95% by mass or less of structural units derived from ethylene and 5% by mass or more and 25% by mass or less of structural units derived from α-olefins having 4 to 12 carbon atoms.

[0036] I The content of the structural units derived from ethylene in the ethylene-based copolymer is preferably 79% by mass or more and 95% by mass or less, more preferably 85% by mass or more and 95% by mass or less, and even more preferably 90% by mass or more and 95% by mass or less. Also, the content of the structural units derived from α-olefins having 4 to 12 carbon atoms in the ethylene-based copolymer is preferably 5% by mass or more and 21% by mass or less, more preferably 5% by mass or more and 15% by mass or less, and even more preferably 5% by mass or more and 10% by mass or less.

[0037] Examples of the α-olefins having 4 to 12 carbon atoms include 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 4-methyl-1-pentene, 4-methyl-1-hexene, etc. From the viewpoint of enhancing the heat seal strength, 1-hexene is preferred. The α-olefins having 4 to 12 carbon atoms are preferably α-olefins having 4 to 8 carbon atoms. The structural units derived from α-olefins having 4 to 12 carbon atoms may be structural units derived from a single α-olefin or structural units derived from two or more α-olefins.

[0038] The density of the ethylene-based copolymer is preferably 850 kg / m 3 or more and 950 kg / m 3The following, and more preferably 850 kg / m 3 More than 930kg / m 3 The following, and more preferably 880 kg / m 3 More than 930kg / m 3 The following is true: The density of the ethylene copolymer is 850 kg / m³. 3 As a result of the above, a film with excellent rigidity can be obtained, with a density of 950 kg / m². 3 The following conditions allow for the creation of a film with excellent tear resistance. The density of the ethylene copolymer is measured according to the method specified in Method A of JIS K7112-1980, and the sample is subjected to annealing as described in JIS K6760-1995.

[0039] The melt flow rate (MFR) of the ethylene copolymer, measured at a temperature of 190°C and a load of 2.16 kg, is preferably 0.1 g / 10 min to 50 g / 10 min, more preferably 0.1 g / 10 min to 10 g / 10 min, and even more preferably 1 g / 10 min to 5 g / 10 min. The MFR is measured by Method A as specified in JIS K7210-1.

[0040] The molecular weight distribution of the ethylene copolymer is preferably 1 to 5, more preferably 1 to 4, and even more preferably 2 to 4. A molecular weight distribution of 1 or more reduces the extrusion load and improves processability. Furthermore, a molecular weight distribution of 5 or less allows for the production of a film with excellent impact resistance at low temperatures. The "molecular weight distribution" refers to the ratio (Mw / Mn) of the weight-average molecular weight (Mw) to the number-average molecular weight (Mn) measured by gel permeation chromatography (hereinafter sometimes referred to as "GPC").

[0041] One method for achieving the above-mentioned molecular weight distribution of an ethylene copolymer is, for example, copolymerizing ethylene and α-olefin using a metallocene catalyst to obtain a density of 850 kg / m³ of the ethylene copolymer. 3 More than 950kg / m 3The following methods can be mentioned.

[0042] The ethylene copolymer can be produced, for example, using a metallocene catalyst. The metallocene catalyst is an olefin polymerization catalyst using, for example, a transition metal compound having a group with a cyclopentadienyl anion skeleton (hereinafter, may be referred to as "metallocene-based transition metal compound").

[0043] Examples of the metallocene-based transition metal compound include compounds represented by the formula MLaXn-a (where M is a transition metal atom of Group 4 of the periodic table of elements or a lanthanide series. L is a group having a cyclopentadienyl anion skeleton or a group containing a heteroatom, and at least one is a group having a cyclopentadienyl anion skeleton. A plurality of Ls may be crosslinked with each other. X is a halogen atom, a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms. n represents the valence of the transition metal atom, and a is an integer satisfying 0 < a ≤ n).

[0044] Examples of the metallocene-based transition metal compound represented by the above formula include bis(1,3-n-butylmethylcyclopentadienyl)zirconium dichloride, bis(1,3-n-propylmethylcyclopentadienyl)zirconium dichloride, bis(n-butylcyclopentadienyl)zirconium dichloride, bis(1,3-dimethylcyclopentadienyl)zirconium dichloride, bis(1,3-diethylcyclopentadienyl)zirconium dichloride, ethylenebis(indenyl)zirconium dichloride, ethylenebis(4-methyl-1-indenyl)zirconium dichloride, ethylenebis(4,5,6,7-tetrahydro-1-indenyl)zirconium dichloride, and the like.

[0045] The metallocene transition metal compounds described above are preferably used in contact with an activation co-catalyst. Examples of activation co-catalysts include almoxane compounds and activation co-catalysts obtained by using organoaluminum compounds in combination with boron compounds such as trityl borate and anilinium borate. They may also be used in combination with particulate supports containing inorganic supports such as SiO2 and Al2O3, or organic supports such as polymers such as ethylene and styrene.

[0046] The resin composition according to this embodiment may contain additives or other resins as needed. Examples of additives include antioxidants, neutralizing agents, ultraviolet absorbers, antistatic agents, lubricants, nucleating agents, adhesives, antifogging agents, antiblocking agents, and melt flow rate modifiers. Examples of antioxidants include phenolic antioxidants, phosphorus-based antioxidants, and sulfur-based antioxidants, and composite antioxidants having a unit that combines a phenolic antioxidant mechanism and a phosphorus-based antioxidant mechanism in one molecule can also be used. Examples of other resins include elastomers such as styrene-butadiene-styrene copolymers and styrene-isoprene-styrene copolymers obtained by hydrogenation.

[0047] In the resin composition according to this embodiment, the content of propylene polymer (1) is preferably 40 parts by mass or more and 80 parts by mass or less, more preferably 40 parts by mass or more and 70 parts by mass or less, even more preferably 50 parts by mass or more and 70 parts by mass or less, and particularly preferably 50 parts by mass or more and 60 parts by mass or less, based on 100 parts by mass of the total content of polymers contained in the resin composition. Furthermore, the content of propylene copolymer (2) is preferably 10 parts by mass or more and 30 parts by mass or less, more preferably 15 parts by mass or more and 30 parts by mass or less, even more preferably 15 parts by mass or more and 25 parts by mass or less, and particularly preferably 22 parts by mass or more and 25 parts by mass or less. Furthermore, the content of propylene copolymer (3) is preferably 2 parts by mass or more and 20 parts by mass or less, more preferably 2 parts by mass or more and 13 parts by mass or less, even more preferably 4 parts by mass or more and 13 parts by mass or less, and particularly preferably 5 parts by mass or more and 10 parts by mass or less. Furthermore, the content of the ethylene copolymer is preferably 5 parts by mass or more and 30 parts by mass or less, more preferably 5 parts by mass or more and 25 parts by mass or less, even more preferably 10 parts by mass or more and 25 parts by mass or less, and particularly preferably 10 parts by mass or more and 20 parts by mass or less.

[0048] In one embodiment of the resin composition according to this embodiment, from the viewpoint of improving the tear resistance and heat seal strength of the film, the content of propylene polymer (1) is preferably 40 parts by mass or more and 80 parts by mass or less, the content of propylene copolymer (2) is preferably 10 parts by mass or more and 30 parts by mass or less, the content of propylene copolymer (3) is preferably 2 parts by mass or more and 20 parts by mass or less, and the content of ethylene copolymer is preferably 5 parts by mass or more and 30 parts by mass or less, based on the total content of polymers contained in the resin composition per 100 parts by mass of polymers.

[0049] <film> The film according to this embodiment contains the above-mentioned resin composition.

[0050] Alternatively, the film according to this embodiment contains an olefin polymer composition and satisfies the following requirements.

[0051] Requirements: The elution behavior of components contained in the film was measured using gradient polymer elution chromatography under the following measurement conditions, and the resulting chromatogram showed the following: The elution peak (X) measured at a retention time of 9.40 minutes or more and less than 10.40 minutes, The elution peak (Y) measured at a retention time of 10.40 minutes or more and less than 12.50 minutes, There is an elution peak (Z) measured at a retention time of 12.50 minutes to 15.50 minutes, The retention time of the peak top of the elution peak (Y) is between 10.40 minutes and 10.80 minutes.

[0052] Measurement conditions: • As the measurement sample, an orthodichlorobenzene solution prepared by dissolving the film at a concentration of 20 mg / 20 mL is used. • Set the column temperature to 165°C. • Butoxyethanol and orthodichlorobenzene are used as the mobile phase. • For the first 2 minutes after the start of measurement, butoxyethanol is introduced into the column at a flow rate of 0.5 mL / min. From 2 to 10 minutes after the start of measurement, butoxyethanol is introduced into the column at a flow rate linearly changing from 0.5 mL / min to 0 mL / min, and orthodichlorobenzene is introduced into the column at a flow rate linearly changing from 0 mL / min to 0.5 mL / min. • From 10 to 15 minutes after the start of measurement, orthodichlorobenzene is introduced into the column at a flow rate of 0.5 mL / min. • From 15 to 25 minutes after the start of measurement, butoxyethanol is introduced into the column at a flow rate of 0.5 mL / min.

[0053] Gradient polymer elution chromatography allows for the separation of polymers contained in the olefin polymer composition according to the content of structural units derived from ethylene, and the compositional distribution can be measured. That is, in the chromatogram, elution peak (X) is considered to correspond to the propylene polymer (1), elution peak (Y) to the propylene copolymer (2) and propylene copolymer (3), and elution peak (Z) to the ethylene copolymer.

[0054] The retention time of the peak top of the elution peak (Y) is 10.40 minutes or more and 10.80 minutes or less, preferably 10.55 minutes or more and 10.75 minutes or less, from the viewpoint of improving the tear resistance and heat seal strength of the film.

[0055] The thickness of the film is preferably 5 μm to 200 μm, and more preferably 50 μm to 100 μm.

[0056] The film according to this embodiment can be manufactured, for example, by a melt-kneading step of melt-kneading the resin composition described above, an extrusion step of extruding the melt-kneaded composition, and a film-forming step of forming a film from the extruded composition.

[0057] In the aforementioned melt-kneading step, a propylene polymer (1), a propylene copolymer (2), a propylene copolymer (3), an ethylene copolymer, and, if necessary, additives or other resins are melt-kneaded together. Note that a multi-stage propylene polymer obtained by polymerizing in multiple stages may be used as the propylene polymer (1) and propylene copolymer (2).

[0058] The melt-kneading process can be carried out using conventionally known methods and apparatus. For example, one method involves mixing the above materials using a mixing device such as a Henschel mixer, ribbon blender, or tumble mixer, and then melt-kneading them. Another method involves obtaining a homogeneous mixture by continuously supplying each of the above materials at a constant ratio using a quantitative feeder, and then melt-kneading the mixture using a single-screw or twin-screw or more extruder, Banbury mixer, roll-type kneader, or the like.

[0059] The resin temperature during melt mixing is preferably 190°C to 320°C, and more preferably 210°C to 280°C.

[0060] In the extrusion process, for example, the molten and kneaded composition is extruded from a T-die using an extruder. The extrusion rate can be, for example, 50 kg / hour or more and 2000 kg / hour or less. The extrusion temperature can be, for example, 200°C or more and 300°C or less. Note that the extrusion temperature is the temperature of the T-die itself.

[0061] In the aforementioned film-forming process, for example, the composition extruded from the T-die is cooled and solidified while being wound up on a chill roll to form a film of a predetermined thickness. The cooling temperature can be, for example, 20°C to 60°C. The film-forming speed can be, for example, 20 m / min to 100 m / min.

[0062] <Multilayer film> The multilayer film according to this embodiment comprises the above-mentioned film as a sealant layer.

[0063] The thickness of the multilayer film is preferably 5 μm or more and 500 μm or less, and more preferably 30 μm or more and 150 μm or less.

[0064] Applications of the multilayer film include, for example, packaging for food, textiles, and general merchandise. Preferably, the multilayer film is one used for packaging retort foods. The multilayer film may also be used as a material for forming packaging bags.

[0065] The aforementioned multilayer film can be manufactured by laminating the above-described film as a sealant layer with a substrate layer. Examples of known film manufacturing methods for laminating the substrate layer and the sealant layer include the T-die method and the tubular method, with the T-die method being preferred.

[0066] The resin composition, film, and multilayer film according to this embodiment are not limited to the above embodiment, and various modifications are possible without departing from the spirit of the present invention. [Examples]

[0067] The present invention will be described in more detail below using examples and comparative examples, but the present invention is not limited to the following examples.

[0068] <Propylene-based polymer composition (1)> Using a Ziegler-Natta type catalyst, propylene was polymerized by gas-phase polymerization in the first step, and then, in the second step, propylene and ethylene were copolymerized by gas-phase polymerization in the presence of the obtained propylene homopolymer to obtain a propylene-based polymer composition. The obtained propylene-based polymer composition contained 77% by mass of propylene homopolymer (component A) and 23% by mass of propylene-ethylene copolymer (component B). In addition, the content of structural units derived from ethylene in component B was 28% by mass. 100 parts by mass of the obtained propylene polymer composition, 0.005 parts by mass of calcium hydroxide, 0.075 parts by mass of Sumirizer GP (2,4,8,10-tetra-t-butyl-6-[3-(3-methyl-4-hydroxy-5-t-butylphenyl)propoxy]dibenzo[d,f][1,3,2]dioxaphosfepine, manufactured by Sumitomo Chemical Co., Ltd.), 0.03 parts by mass of Sumirizer GS (2,4-di-t-amyl-6-[1-(3,5-di-t-amyl-2-hydroxyphenyl)ethyl]phenyl acrylate, manufactured by Sumitomo Chemical Co., Ltd.), and an appropriate amount of melt flow rate modifier (2,5-dimethyl-2,5-di(tert-butylperoxy)hexane) were mixed in a Henschel mixer, and then melt extrusion was performed to obtain a pelletized propylene polymer composition (1). The obtained propylene polymer composition (1) had a melt flow rate of 3 g / 10 min, measured at 230°C.

[0069] <Propylene-based polymer composition (2)> Using a Ziegler-Natta type catalyst, propylene was polymerized by gas-phase polymerization in the first step, and then, in the second step, propylene and ethylene were copolymerized by gas-phase polymerization in the presence of the obtained propylene homopolymer to obtain a propylene-based polymer composition. The obtained propylene-based polymer composition contained 70% by mass of propylene homopolymer (component A) and 30% by mass of propylene-ethylene copolymer (component B). In addition, the content of structural units derived from ethylene in component B was 28% by mass. 100 parts by mass of the obtained propylene polymer composition, 0.005 parts by mass of calcium hydroxide, 0.075 parts by mass of Sumirizer GP (2,4,8,10-tetra-t-butyl-6-[3-(3-methyl-4-hydroxy-5-t-butylphenyl)propoxy]dibenzo[d,f][1,3,2]dioxaphosfepine, manufactured by Sumitomo Chemical Co., Ltd.), 0.03 parts by mass of Sumirizer GS (2,4-di-t-amyl-6-[1-(3,5-di-t-amyl-2-hydroxyphenyl)ethyl]phenyl acrylate, manufactured by Sumitomo Chemical Co., Ltd.), and an appropriate amount of melt flow rate modifier (2,5-dimethyl-2,5-di(tert-butylperoxy)hexane) were mixed in a Henschel mixer, and then melt extrusion was performed to obtain a pelletized propylene polymer composition (2). The obtained propylene polymer composition (2) had a melt flow rate of 3 g / 10 min, measured at 230°C.

[0070] The content of components A and B in the propylene polymer composition was determined from the mass balance during polymerization of components A and B.

[0071] The content of ethylene-derived structural units in component B of the propylene polymer composition was calculated by measuring the overall IR spectrum of the propylene polymer composition and following the method described in "(ii) Method for block copolymers" on page 616 of the Polymer Analysis Handbook (1995, Kinokuniya Shoten), using the following formula (1). E B =(E T -E A ×P A ) / P B (1) (In the formula, E T , E A and E B These indicate the content of ethylene-derived structural units in the propylene polymer composition, component A, and component B, respectively, and P A and P B (These indicate the content of component A and component B, respectively.)

[0072] <Propylene-ethylene copolymer (1)> VERSIFY2000 (manufactured by Dow Chemical Japan Ltd.) was used as the propylene-ethylene copolymer (1). The propylene-ethylene copolymer (1) had a propylene-derived structural unit content of 95% by mass and an ethylene-derived structural unit content of 5% by mass, a melt flow rate of 2 g / 10 min measured at 230°C, and a density of 888 kg / m³. 3 That was the case.

[0073] <Propylene-ethylene copolymer (2)> As the propylene-ethylene copolymer (2), VERSIFY4301 (manufactured by Dow Chemical Japan Ltd.) was used. The propylene-ethylene copolymer (2) had a structural unit content of 88% by mass derived from propylene and a structural unit content of 12% by mass derived from ethylene, a melt flow rate of 25 g / 10 min measured at 230°C, and a density of 867 kg / m³. 3 That was the case.

[0074] <Propylene-ethylene copolymer (3)> Vistamaxx6202FL (manufactured by ExxonMobil Japan LLC) was used as the propylene-ethylene copolymer (3). The propylene-ethylene copolymer (3) had a propylene-derived structural unit content of 85% by mass and an ethylene-derived structural unit content of 15% by mass, a melt flow rate of 20 g / 10 min measured at 230°C, and a density of 861 kg / m³. 3 That was the case.

[0075] The melt flow rates of the propylene-based polymer composition and the propylene-ethylene copolymer were measured according to Method A specified in JIS K7210-1 at a temperature of 230°C and a load of 2.16 kg.

[0076] <Ethylene copolymer (1)> As the ethylene copolymer (1), ethylene-butene-1 copolymer (Tafmer A4085s, manufactured by Mitsui Chemicals, Inc.) was used. The ethylene copolymer (1) had a structural unit content of 80% by mass derived from ethylene and a structural unit content of 20% by mass derived from 1-butene, a melt flow rate of 3.6 g / 10 min measured at 190°C, and a density of 885 kg / m³. 3 That was the case.

[0077] <Ethylene copolymer (2)> As the ethylene copolymer (2), ethylene-1-hexene copolymer (Sumikasen E FV205, manufactured by Sumitomo Chemical Co., Ltd.) was used. The ethylene copolymer (2) had a structural unit content of 93% by mass derived from ethylene and 7% by mass derived from 1-hexene, a melt flow rate of 2.2 g / 10 min measured at 190°C, and a density of 921 kg / m³. 3 That was the case.

[0078] The melt flow rate of the ethylene copolymer was measured according to Method A specified in JIS K7210-1, at a temperature of 190°C and a load of 2.16 kg.

[0079] The densities of the propylene-ethylene copolymer and the ethylene-based copolymer were measured according to the method specified in Method A of JIS K7112-1980. The samples were subjected to annealing as described in JIS K6760-1995.

[0080] <Example 1> A resin composition was prepared by pelletizing and blending 80% by mass of propylene polymer composition (2), 10% by mass of propylene-ethylene copolymer (1), and 10% by mass of ethylene copolymer (1). This composition was melt-kneaded using three extruders: a 90 mmφ extruder and two 65 mmφ extruders, each equipped with a metal filter with a filtration accuracy of 40 μm. The melt-kneaded resin composition was then extruded. Next, the resin compositions extruded from each of the three extruders were combined in a feed block and fed into a T-die (die width 1250 mm, lip opening 0.8 mm), where melt extrusion was performed at a die temperature of 240 °C. The extruded molten film was cooled and solidified using a chill roll (rotation speed 50 m / min, cooling temperature 50 °C) to obtain a film with a thickness of 70 μm.

[0081] <Example 2> A film was obtained in the same manner as in Example 1, except that a resin composition was used which was a pelletized blend of 80% by mass of propylene polymer composition (2), 5% by mass of propylene-ethylene copolymer (3), and 15% by mass of ethylene copolymer (2).

[0082] <Example 3> A film was obtained in the same manner as in Example 1, except that a resin composition was used which was a pellet blend of 75% by mass of propylene polymer composition (2), 5% by mass of propylene-ethylene copolymer (3), and 20% by mass of ethylene copolymer (2).

[0083] <Example 4> A film was obtained in the same manner as in Example 1, except that a resin composition was used which was a pellet blend of 80% by mass of propylene polymer composition (2), 5% by mass of propylene-ethylene copolymer (2), and 15% by mass of ethylene copolymer (2).

[0084] <Comparative Example 1> A film was obtained in the same manner as in Example 1, except that a resin composition was used which was a pelletized blend of 80% by mass of a propylene polymer composition (2) and 20% by mass of an ethylene copolymer (2).

[0085] <Comparative Example 2> A film was obtained in the same manner as in Example 1, except that a resin composition was used which was a pelletized blend of 85% by mass of a propylene polymer composition (1) and 15% by mass of a propylene-ethylene copolymer (2).

[0086] <Component separation using gradient polymer elution chromatography> The elution behavior of the components contained in the obtained film was measured using gradient polymer elution chromatography under the following measurement conditions.

[0087] <Preparation of orthodichlorobenzene solution sample> After wrapping the film in a 2300-mesh wire mesh, a 20 mg / 20 mL orthodichlorobenzene solution sample was prepared by stirring in orthodichlorobenzene containing 0.05% by mass of dibutylhydroxytoluene as a stabilizer at 145°C for 2 hours. As a standard sample, FLX80E4 (manufactured by Sumitomo Chemical Co., Ltd.), a propylene homopolymer, was wrapped in a 2300-mesh wire mesh. This was then stirred in orthodichlorobenzene containing 0.05% by mass of dibutylhydroxytoluene as a stabilizer at 145°C for 2 hours to prepare a 10 mg / 20 mL orthodichlorobenzene solution standard sample.

[0088] <Measurement of elution behavior using gradient polymer elution chromatography> 25 μL of the obtained orthodichlorobenzene solution sample was injected into the column via an autosampler, injector, and valve oven. The autosampler temperature was controlled to 155°C, the injector's injection valve temperature to 155°C, the injector piping and valve oven piping temperatures to 155°C, and the valve oven temperature to 140°C. A Thermo Hypercarb column (φ4.6 mm × 100 mm, particle size 5 μm) was used as the gradient polymer elution chromatography column, and the column temperature was controlled to 165°C. An evaporative light scattering detector (ELSD) was used as the detector. The temperature of the piping to the detector was controlled to 165°C, the detector's atomizer temperature was controlled to 170°C, and the evaporator temperature was controlled to 210°C. Measurements were performed while flowing nitrogen gas at 250°C and a flow rate of 2.7 L / min.

[0089] Butoxyethanol and orthodichlorobenzene were used as the mobile phase. The mobile phase was combined with the orthodichlorobenzene solution sample injected from the injector in a valve oven, and then injected into the column. For the first 2 minutes after the start of measurement, butoxyethanol was introduced into the column at a flow rate of 0.5 ml / min. From 2 to 10 minutes after the start of measurement, butoxyethanol was introduced into the column while the flow rate was linearly changed from 0.5 mL / min to 0 mL / min, and orthodichlorobenzene was introduced into the column while the flow rate was linearly changed from 0 mL / min to 0.5 mL / min (i.e., the sum of the flow rates of butoxyethanol and orthodichlorobenzene was maintained at 0.5 mL / min). From 10 to 15 minutes after the start of measurement, orthodichlorobenzene was introduced into the column at a flow rate of 0.5 mL / min. Butoxyethanol was introduced into the column at a flow rate of 0.5 mL / min from 15 to 25 minutes after the start of measurement.

[0090] <Method for analyzing measurement data> First, measurements were performed using only the mobile phase, and the system peak was confirmed using the resulting chromatogram. Next, measurements were performed using an orthodichlorobenzene solution standard sample, and the elution peak of the standard sample was confirmed using the resulting chromatogram. The peak top retention time Ts of the elution peak of the standard sample was determined, and the correction time Tc was calculated using the following equation (2). Tc = 10 - Ts (2) Next, measurements were performed using an orthodichlorobenzene solution sample. From the resulting chromatogram, data from 9.0 to 16.0 minutes after the start of measurement were extracted and corrected with a correction time Tc. After retention time correction, the baseline data was obtained from the data from 9.0 to 16.0 minutes after the start of measurement. The baseline data was then fitted using the quintic function shown in equation (3) below, using the data from 9.0 to 9.5 minutes, 12.0 to 13.0 minutes, and 15.0 to 16.0 minutes after the start of measurement. The baseline fitting function was then obtained. Using the obtained function, the baseline data of the chromatogram was corrected by subtracting the baseline data from the data after retention time correction. After baseline correction of the chromatogram, the retention time of the elution peak and the retention time of the peak top were determined.

[0091] Y=a5X 5 +a4X 4 +a3X 3 +a2X 2 +a1X+a0(3)

[0092] The presence or absence of an elution peak (X) measured at a retention time of 9.40 minutes or more but less than 10.40 minutes, the presence or absence of an elution peak (Y) measured at a retention time of 10.40 minutes or more but less than 12.50 minutes, the presence or absence of an elution peak (Z) measured at a retention time of 12.50 minutes or more but less than 15.50 minutes, and the retention time of the peak top of elution peak (Y) were determined. The results are shown in Table 1.

[0093] <Multilayer film> The film obtained above (hereinafter also referred to as sealant film), aluminum foil (thickness 7 μm), and polyethylene terephthalate film (thickness 12 μm) were laminated in the order described above by dry lamination to obtain a multilayer film.

[0094] <Heat seal strength> Using a heat sealer manufactured by Toyo Tester Industries Co., Ltd., two multilayer films were overlapped with the sealant film side facing inward, and the direction of the sealing bar was aligned perpendicular to the flow direction (MD) of the sealant film, and then heat-sealed in a strip shape under the following conditions. • Seal bar: Flat, single-sided heating • Sealing temperature: 200℃ • Seal pressure: 1.0 kg / cm² 2 • Sealing time: 1.0 sec • Seal width: 10mm

[0095] A 15 mm wide test specimen was cut from a heat-sealed multilayer film perpendicular to the seal width direction. Using a tensile testing machine (Orientec Tensilon), the test specimen was peeled at a peel angle of 90° and a tensile speed of 200 mm / min, and the maximum peel strength was defined as the heat seal strength. The measurement results are shown in Table 1.

[0096] <Drop bag strength> Using multilayer film, 15cm x 18cm three-sided pouches were created using a standing pouch making machine (manufactured by Seibu Machinery Co., Ltd.). Additionally, 160g of water was filled into the resulting three-sided pouches and sealed to create water-filled packaging bags.

[0097] After conditioning the water-filled packaging bags at 5°C for 24 hours, a 1kg weight was repeatedly dropped onto the water-filled packaging bags from a height of 250mm, and the number of drops required for the water-filled packaging bags to burst was measured. The measurement was performed for each water-filled packaging bag, from n=1 to 10 (i.e., 10 bags each). The number of drops required for each of the n=1 to 10 water-filled packaging bags to burst was then calculated as X1 to X 10The bag drop strength was calculated using the following formula (4).

[0098]

number

[0099] [Table 1]

[0100] As can be seen from the results in Table 1, the resin compositions of each embodiment that satisfy all the constituent requirements of the present invention have high drop strength, and therefore a film with relatively good tear resistance can be obtained. Furthermore, the resin compositions of each embodiment can be used to obtain a sealant film with excellent heat seal strength.

[0101] On the other hand, the resin composition of Comparative Example 1 does not contain a propylene copolymer (3), and the retention time of the peak top of the elution peak (Y) does not meet the range of the present invention, so the tear resistance and heat seal strength of the film obtained using this resin composition are inferior. The resin composition of Comparative Example 2 does not contain an ethylene copolymer, and there is no elution peak (Z), so the tear resistance of the film obtained using this resin composition is inferior.

Claims

1. A propylene polymer (1) containing 97% by mass or more of structural units derived from propylene, A propylene copolymer (2) comprising 60% by mass or more and less than 80% by mass of structural units derived from propylene, and more than 20% by mass and 40% by mass or less of structural units derived from ethylene and at least one selected from the group consisting of α-olefins having 4 to 12 carbon atoms, A propylene copolymer (3) comprising 80% by mass or more and 88% by mass or less of structural units derived from propylene, and 12% by mass or more and 20% by mass or less of structural units derived from at least one selected from the group consisting of ethylene and α-olefins having 4 to 12 carbon atoms, An ethylene-based copolymer containing 75% to 95% by mass of structural units derived from ethylene and 5% to 25% by mass of structural units derived from α-olefins having 4 to 12 carbon atoms, Includes, The content of the ethylene copolymer is 10 parts by mass or more and 30 parts by mass or less, relative to 100 parts by mass of the total content of polymers contained in the resin composition. A resin composition wherein the film containing the aforementioned resin composition satisfies the following requirements. Requirements: The elution behavior of components contained in the film was measured using gradient polymer elution chromatography under the following measurement conditions, and the resulting chromatogram showed the following: The elution peak (X) measured at a retention time of 9.40 minutes or more and less than 10.40 minutes, The elution peak (Y) measured at a retention time of 10.40 minutes or more and less than 12.50 minutes, There is an elution peak (Z) measured at a retention time of 12.50 minutes or more and 15.50 minutes or less, The retention time of the peak top of the elution peak (Y) is between 10.40 minutes and 10.80 minutes. Measurement conditions: - As the measurement sample, an orthodichlorobenzene solution prepared by dissolving the film at a concentration of 20 mg / 20 mL will be used. - Set the column temperature to 165°C. Butoxyethanol and orthodichlorobenzene are used as the mobile phase. - For the first two minutes after the start of measurement, infuse butoxyethanol into the column at a flow rate of 0.5 mL / min. From 2 to 10 minutes after the start of measurement, butoxyethanol is introduced into the column at a flow rate linearly changing from 0.5 mL / min to 0 mL / min, and orthodichlorobenzene is introduced into the column at a flow rate linearly changing from 0 mL / min to 0.5 mL / min. - For 10 to 15 minutes after the start of measurement, orthodichlorobenzene is introduced into the column at a flow rate of 0.5 mL / min. - From 15 to 25 minutes after the start of measurement, butoxyethanol is introduced into the column at a flow rate of 0.5 mL / min.

2. With respect to 100 parts by mass of the total amount of polymer contained in the resin composition, The content of the propylene polymer (1) is 40 parts by mass or more and 80 parts by mass or less. The content of the propylene copolymer (2) is 10 parts by mass or more and 30 parts by mass or less. The resin composition according to claim 1, wherein the content of the propylene copolymer (3) is 2 parts by mass or more and 20 parts by mass or less.

3. The resin composition according to claim 1 or 2, wherein the propylene copolymer (3) is a propylene-ethylene copolymer.

4. The propylene polymer (1) is a propylene homopolymer, The resin composition according to any one of claims 1 to 3, wherein the propylene copolymer (2) is a propylene-ethylene copolymer.

5. A propylene polymer (1) containing 97% by mass or more of structural units derived from propylene, A propylene copolymer (2) comprising 60% by mass or more and less than 80% by mass of structural units derived from propylene, and more than 20% by mass and 40% by mass or less of structural units derived from ethylene and at least one selected from the group consisting of α-olefins having 4 to 12 carbon atoms, A propylene copolymer (3) comprising 80% by mass or more and 88% by mass or less of structural units derived from propylene, and 12% by mass or more and 20% by mass or less of structural units derived from at least one selected from the group consisting of ethylene and α-olefins having 4 to 12 carbon atoms, An ethylene-based copolymer containing 75% to 95% by mass of structural units derived from ethylene and 5% to 25% by mass of structural units derived from α-olefins having 4 to 12 carbon atoms, Includes, A film containing a resin composition in which the content of the ethylene copolymer is 10 parts by mass or more and 30 parts by mass or less, based on the total content of polymers contained in the resin composition (100 parts by mass or less).

6. The film according to claim 5, which satisfies the following requirements. Requirements: The elution behavior of components contained in the film was measured using gradient polymer elution chromatography under the following measurement conditions, and the resulting chromatogram showed the following: The elution peak (X) measured at a retention time of 9.40 minutes or more and less than 10.40 minutes, The elution peak (Y) measured at a retention time of 10.40 minutes or more and less than 12.50 minutes, There is an elution peak (Z) measured at a retention time of 12.50 minutes or more and 15.50 minutes or less, The retention time of the peak top of the elution peak (Y) is between 10.40 minutes and 10.80 minutes. Measurement conditions: - As the measurement sample, an orthodichlorobenzene solution prepared by dissolving the film at a concentration of 20 mg / 20 mL will be used. - Set the column temperature to 165°C. Butoxyethanol and orthodichlorobenzene are used as the mobile phase. - For the first two minutes after the start of measurement, infuse butoxyethanol into the column at a flow rate of 0.5 mL / min. From 2 to 10 minutes after the start of measurement, butoxyethanol is introduced into the column at a flow rate linearly changing from 0.5 mL / min to 0 mL / min, and orthodichlorobenzene is introduced into the column at a flow rate linearly changing from 0 mL / min to 0.5 mL / min. - For 10 to 15 minutes after the start of measurement, orthodichlorobenzene is introduced into the column at a flow rate of 0.5 mL / min. - From 15 to 25 minutes after the start of measurement, butoxyethanol is introduced into the column at a flow rate of 0.5 mL / min.

7. A multilayer film comprising the film according to claim 5 or 6 as a sealant layer.

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