Olefin polymer composition, sealant film, non-stretched film and inflation film

Abstract

To provide an olefinic polymer composition excellent in opening property or anti-blocking property, and heat sealability at a low temperature of an obtained film.SOLUTION: Provided are an olefinic polymer composition including: a propylene-based polymer (A) having a melting point (Tm) measured by differential scanning calorimetry (DSC) of 120°C or higher and 170°C or lower; an olefinic polymer (B) having a melting point (Tm) measured by differential scanning calorimetry (DSC) of 30°C or higher and lower than 120°C; and a cross-linked product (C) of an ultrahigh molecular weight-having olefinic polymer satisfying requirements (C-i)-(C-iii), a sealant film including the same, and a non-stretched film including a layer formed from the same and an inflation film. (C-i) The intrinsic viscosity [η] measured in a decalin solvent at 135°C is 5dl / g-50dl / g. (C-ii) The average particle diameter d50 is 3 μm-30 μm. (C-iii) The passing amount of a sieve having an aperture of 37 μm mesh is 95 mass% or more.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an olefin polymer composition, a sealant film, a non-oriented film, and an inflation film. [Background technology]

[0002] Films made of olefin polymers are excellent in transparency, mechanical properties, etc., and are therefore widely used as various packaging materials. However, it is known that when films made of olefin polymers are stacked together, for example, in a laminated or rolled form, the films adhere to each other, a phenomenon known as blocking. Therefore, in order to improve the ability to suppress the blocking phenomenon (i.e., blocking resistance) of olefin polymer films, Patent Document 1, for example, discloses that an antiblocking agent is added to improve blocking resistance.

[0003] Furthermore, for example, Patent Document 2 discloses inorganic substances such as finely powdered silica, zeolite, talc, calcium carbonate, and diatomaceous earth as antiblocking agents for olefin polymer films. Furthermore, for example, Patent Document 3 discloses a method of using acrylic resin particles as an antiblocking agent.

[0004] For example, Patent Document 4 discloses a masterbatch for inflation film molding, which is a resin composition for inflation film molding intended to eliminate the resin powder that bleeds onto the film surface during inflation film production using high-density polyethylene resin, known as powdering. The masterbatch is composed of 100 parts by weight of polyethylene resin having an MFR of 0.05 or more, 1 to 30 parts by weight of polypropylene resin, and 1 to 50 parts by weight of inorganic powder having an average particle size of 0.5 to 30 μm. For example, Patent Document 5 discloses an olefin polymer composition containing an olefin polymer and a crosslinked ultra-high molecular weight olefin polymer obtained by crosslinking an ultra-high molecular weight olefin polymer satisfying specific physical properties through irradiation. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 6-73202 [Patent Document 2] Japanese Patent Application Publication No. 49-23245 [Patent Document 3] International Publication No. 2009 / 044925 [Patent Document 4] Japanese Patent Application Laid-Open No. 2000-319456 [Patent Document 5] Japanese Patent Application Laid-Open No. 2013-245345 Summary of the Invention [Problem to be solved by the invention]

[0006] For example, the inorganic substance used as an antiblocking agent for olefin polymer films described in Patent Document 2 is highly hard and amorphous, which means that when films with inorganic substances on their surfaces rub against each other, the films are easily damaged. The acrylic resin particles described in Patent Document 3 have insufficient affinity with olefin polymers, which means that the antiblocking agent composed of acrylic resin particles falls off during film formation or secondary processing. The resin composition or masterbatch for inflation molding described in Patent Document 4 does not specifically address the blocking resistance. The olefin film described in Patent Document 5 does not specifically address the low-temperature heat sealability. Furthermore, Patent Document 5 does not address the use of cast-molded films, which exhibit high blocking strength due to the smooth film surface obtained during inflation molding. The mere use of conventional antiblocking agents described in Patent Documents 1 to 5 does not sufficiently resolve the problem of easy peeling between inner layers of an olefin polymer film during inflation molding (opening property). Furthermore, there is a demand for further performance that combines opening property or anti-blocking property with low-temperature heat sealability.

[0007] An object of one embodiment of the present invention is to provide an olefin polymer composition that provides a film having excellent opening properties or blocking resistance and low-temperature heat sealability. Another object of one embodiment of the present invention is to provide a sealant film and a non-oriented film that have excellent opening properties or blocking resistance and low-temperature heat sealability. Another object of one embodiment of the present invention is to provide an inflation film that has excellent opening properties and low-temperature heat sealability. [Means for solving the problem]

[0008] The means for solving the above problems include the following aspects. <1> a propylene polymer (A) having a melting point (Tm) measured by differential scanning calorimetry (DSC) of 120°C or higher and 170°C or lower; An olefin polymer (B) having a melting point (Tm) measured by differential scanning calorimetry (DSC) of 30°C or higher and lower than 120°C, and An olefin polymer composition comprising (C) a crosslinked product of an ultra-high molecular weight olefin polymer that satisfies the following requirements (Ci) to (C-iii): (Ci) Intrinsic viscosity [η] measured in decalin solvent at 135°C is 5 dl / g to 50 dl / g (C-ii) Average particle diameter d 50 However, 3μm~30μm (C-iii) 95% by mass or more of the material passes through a 37 μm mesh sieve <2> When the total amount of the propylene polymer (A) and the olefin polymer (B) is taken as 100% by mass, the content of the propylene polymer (A) is 10% by mass to 90% by mass, and the content of the olefin polymer (B) is 10% by mass to 90% by mass. <1> The olefin polymer composition according to claim 1. <3> The olefin polymer (B) contains at least one olefin polymer selected from the group consisting of an ethylene polymer (B1), a propylene polymer (B2), and a 1-butene polymer (B3). <1> or <2> The olefin polymer composition according to claim 1. <4> the content of the crosslinked ultra-high molecular weight olefin polymer (C) is 100 ppm to 10,000 ppm relative to 100 parts by mass of the total of the propylene polymer (A) and the olefin polymer (B); <1> ~ <3> The olefin polymer composition according to any one of the above items. <5> The ultra-high molecular weight olefin polymer is an ultra-high molecular weight ethylene polymer. <1> ~ <4> The olefin polymer composition according to any one of the above. <6> <1> ~ <5> 1. A sealant film comprising a layer formed from the olefin polymer composition according to any one of the above items. <7> <1> ~ <5> An unstretched film comprising the olefin polymer composition according to any one of the above items. <8> <1> ~ <5> 1. An inflation film comprising the olefin polymer composition according to any one of claims 1 to 9. [Effects of the Invention]

[0009] According to one embodiment of the present invention, there is provided an olefin polymer composition which provides a film having excellent opening properties or blocking resistance and low-temperature heat sealability. Also, according to one embodiment of the present invention, there is provided a sealant film and a non-oriented film which have excellent opening properties or blocking resistance and low-temperature heat sealability. Also, according to one embodiment of the present invention, there is provided an inflation film which has excellent opening properties and low-temperature heat sealability. DETAILED DESCRIPTION OF THE INVENTION

[0010] The present invention will be described in detail below. The following description of the components may be based on a representative embodiment of the present invention, but the present invention is not limited to such an embodiment. In this specification, the term "polymer" is a concept that includes homopolymers and copolymers. In the present invention, the term "film" is a general term for a flat molded product, and includes not only films but also sheets, membranes, tapes, and the like.

[0011] In this specification, the use of "to" to indicate a range of values ​​means that the values ​​before and after it are included as the lower and upper limits. In addition, unless otherwise specified in this specification, each component in the composition or each structural unit in the polymer may be contained alone or in combination of two or more types.

[0012] In this specification, the amount of each component in a composition or each structural unit in a polymer means, when a plurality of substances or structural units corresponding to each component or each structural unit in a polymer are present in the composition, the total amount of the corresponding substance present in the composition or each structural unit present in the polymer, unless otherwise specified. As used herein, a combination of two or more preferred embodiments is a more preferred embodiment. The present invention will be described in detail below.

[0013] (Olefin polymer composition) The olefin polymer composition according to the present invention comprises a propylene polymer (A) (hereinafter also referred to as "specific propylene polymer (A)") having a melting point (Tm) measured by differential scanning calorimetry (DSC) of 120°C or more and 170°C or less, an olefin polymer (B) (hereinafter also referred to as "specific olefin polymer (B)") having a melting point (Tm) measured by differential scanning calorimetry (DSC) of 30°C or more and less than 120°C, and The composition contains a crosslinked ultra-high molecular weight olefin polymer (C) that satisfies the following requirements (Ci) to (C-iii): (Ci) Intrinsic viscosity [η] measured in decalin solvent at 135°C is 5 dl / g to 50 dl / g (C-ii) Average particle diameter d 50 However, 3μm~30μm (C-iii) At least 95% by mass passes through a 37 μm mesh sieve

[0014] As a result of extensive investigations, the inventors have found that by incorporating into an olefin polymer composition a propylene polymer (A) having a melting point within a specific range, an olefin polymer (B) having a melting point within a specific range, and a crosslinked product of a specific ultra-high molecular weight olefin polymer, the resulting film has excellent heat seal strength at low temperatures (hereinafter also referred to as "low-temperature heat sealability") and excellent peelability between inner layers of the film during inflation molding (hereinafter simply referred to as "openability") or excellent suppression of blocking between films during cast molding (blocking resistance). The reason for this is not clear, but is presumed to be as follows.

[0015] The crosslinked product of the specific ultra-high molecular weight olefin polymer contained in the ethylene copolymer composition of the present invention satisfies the requirements (Ci) to (C-iii), and therefore has a smaller particle size than conventional olefin polymer particles, and is crosslinked between molecules, resulting in a higher molecular weight, which is thought to improve heat resistance. It is also thought that the particles are finely dispersed throughout the polymer composition without agglomeration during melt-kneading. As a result, the presence of polymer agglomerates in the resulting film can be reduced, and even when a film is formed, the film surface has uniform irregularities. Compared to films containing inorganic particles as conventional antiblocking agents, the crosslinked product of the specific ultra-high molecular weight olefin polymer is less likely to slide off, resulting in excellent opening properties and anti-blocking properties. Furthermore, it is presumed that the olefin polymer composition according to the present invention contains a propylene polymer (A) having a melting point within a specific range and an olefin polymer (B) having a melting point within a specific range, and therefore the olefin polymer (B) melts at a low temperature during heat sealing, and the olefin polymers (B) in opposing sealant layers fuse together, resulting in excellent low-temperature heat sealability. Hereinafter, each component of the olefin polymer composition according to the present invention will be described.

[0016] <Crosslinked Ultra-High Molecular Weight Olefin Polymer (C)> The olefin polymer composition according to the present invention contains a crosslinked product (C) (hereinafter, may be simply referred to as "crosslinked product (C)") of an ultra-high molecular weight olefin polymer (hereinafter, may be referred to as "specific ultra-high molecular weight olefin polymer") that satisfies the above requirements (Ci) to (C-iii).

[0017] <<Specific ultra-high molecular weight olefin polymer>> [(Ci)] The specific ultra-high molecular weight olefin polymer satisfies the requirement that the intrinsic viscosity [η] measured in decalin solvent at (Ci) 135° C. is 5 dl / g to 50 dl / g. In the present invention, an olefin polymer having an intrinsic viscosity [η] of 5 dl / g or more measured in decalin solvent at 135° C. may be referred to as an ultra-high molecular weight olefin polymer. In the present invention, the ultra-high molecular weight olefin polymer has an intrinsic viscosity [η] measured in decalin solvent at 135°C of 5 dl / g to 50 dl / g, preferably 5 dl / g to 40 dl / g, and more preferably 5 dl / g to 30 dl / g. It is preferable that the intrinsic viscosity is in the range of 5 dl / g to 50 dl / g, since this provides excellent wear resistance and self-lubricating properties.

[0018] [(C-ii)] The specific ultra-high molecular weight olefin polymer has (C-ii) an average particle diameter d 50 However, the requirement that the thickness is 3 μm to 30 μm is met. Average particle diameter d 50 When the average particle diameter d is 30 μm or less, the impact strength of the film obtained by blending with the specific olefin polymer (A) described later is improved, and the appearance of the obtained film is also improved, which is preferable. 50 If the particle size is 3 μm or more, handling of the particles during film formation is favorable, which is preferable. Average particle size d of ultra-high molecular weight olefin polymer 50 is determined by measuring the weight-based particle size distribution by the Coulter counter method, and means the value at which the integrated value of the particle shape distribution is 50 mass %. Average particle size d of ultra-high molecular weight olefin polymer 50 From the above viewpoint, the thickness is preferably 3 μm to 25 μm, more preferably 3 μm to 20 μm, and even more preferably 3 μm to 15 μm.

[0019] [(C-iii)] The specific ultra-high molecular weight olefin polymer satisfies the requirement (iii) that the amount passing through a 37 μm mesh sieve is 95% by mass or more. In this specification, the specific ultra-high molecular weight olefin polymer refers to a polymer that is sieved using a vibrating sieve or an ultrasonic vibrating sieve, and 95 mass% or more of the total mass of the specific ultra-high molecular weight olefin polymer passes through a mesh sieve (Tyler #400) with an opening of 37 μm. The fact that the amount passing through a 37 μm mesh sieve is more than 95% by weight means that the amount of coarse particles present in the ultra-high molecular weight olefin polymer is small. When the amount of coarse particles present is small, when an olefin polymer composition contains a crosslinked ultra-high molecular weight olefin polymer (C) produced from the ultra-high molecular weight olefin polymer, the ultra-high molecular weight olefin polymer (particles) tend to be uniformly dispersed in the composition, which is considered to be preferable because it efficiently contributes to improving the opening property and blocking resistance. From this point of view, the amount of material passing through a 37 μm mesh sieve is preferably 90% by mass or more, more preferably 95% by mass or more, and even more preferably 99% by mass or more.

[0020] The composition of the specific ultra-high molecular weight olefin polymer is not particularly limited as long as it satisfies the above requirements (Ci) to (C-iii). Examples of the specific ultra-high molecular weight olefin polymer include homopolymers such as polyethylene, polypropylene, poly-1-butene, and poly-4-methyl-1-pentene, and copolymers of ethylene with a small amount of other α-olefin, such as ethylene with propylene, 1-butene, 1-hexene, 1-octene, or 4-methyl-1-pentene. Among these, the specific ultra-high molecular weight olefin polymer is preferably an ethylene polymer (ultra-high molecular weight ethylene polymer) from the viewpoint of excellent low-temperature heat sealability, and more preferably an ethylene homopolymer (ultra-high molecular weight ethylene polymer).

[0021] In the present invention, the method for producing the specific ultra-high molecular weight olefin polymer is not particularly limited as long as the specific ultra-high molecular weight olefin polymer satisfies the above requirements (Ci) to (C-iii). For example, the specific ultra-high molecular weight olefin polymer can be produced by the methods disclosed in the following documents (1) to (5). (1) International Publication No. 2006 / 054696 (2) International Publication No. 2008 / 013144 (3) International Publication No. 2009 / 011231 (4) International Publication No. 2010 / 074073 (5) JP 2012-131959 A

[0022] The crosslinked product (C) is a crosslinked product of a specific ultra-high molecular weight olefin polymer, and the method for crosslinking the specific ultra-high molecular weight olefin polymer is not particularly limited as long as the desired effect is obtained. Examples of the crosslinking method include a crosslinking method using heat, and a crosslinking method using actinic rays, radiation, or the like. Among these, a crosslinking method using radiation is preferred from the viewpoint of excellent opening properties and blocking resistance.

[0023] The present inventors presume that irradiation of the specific ultra-high molecular weight olefin polymer causes scission and crosslinking of molecular chains in the polymer, resulting in the molecular chains being linked at the crosslinking points, which makes it difficult for the molecular chains to flow freely even at temperatures above the glass transition temperature or melting point, improving high-temperature properties, and allowing the polymer to maintain its shape even under stress, thereby maintaining mechanical properties. From this point of view, the crosslinked product (C) is preferably a crosslinked product obtained by irradiating the above-mentioned specific ultra-high molecular weight olefin polymer with radiation.

[0024] The radiation is not particularly limited, and examples thereof include α-rays, β-rays, γ-rays, electron beams, ions, etc., with electron beams and γ-rays being preferred.

[0025] The radiation exposure dose can be appropriately set depending on the type of monomer that constitutes the specific ultra-high molecular weight olefin polymer used, and is usually preferably 20 to 700 kGy, more preferably 100 to 500 kGy. When the irradiation dose is within the above range, the crosslinking reaction of the ultra-high molecular weight olefin polymer can be efficiently promoted. Furthermore, when the crosslinked product (C) of the specific ultra-high molecular weight olefin polymer obtained in this manner is contained in an olefin polymer composition, it becomes possible to suppress re-aggregation of the crosslinked product (C) (particles) of the specific ultra-high molecular weight olefin polymer.

[0026] From the viewpoint of achieving both good opening properties and low-temperature heat sealability, the content of the crosslinked ultra-high molecular weight olefin polymer (C) is preferably 100 ppm (parts per million) to 10,000 ppm, and more preferably 100 ppm to 5000 ppm, relative to the total mass of the olefin polymer composition.

[0027] From the viewpoint of opening property and low-temperature heat sealing property, the content of the crosslinked ultrahigh molecular weight olefin polymer (C) is preferably 100 ppm (parts per million) to 10,000 ppm, more preferably 200 ppm to 8,000 ppm, even more preferably 400 ppm to 4,000 ppm, particularly preferably 500 ppm to 2,000 ppm, and most preferably 600 ppm to 1,500 ppm, relative to 100 parts by mass of the total of the propylene polymer (A) and the olefin polymer (B). The crosslinked ultra-high molecular weight olefin polymer (C) may be one type alone or two or more types in combination.

[0028] <Specific Propylene Polymer (A)> The specific propylene polymer (A) has a melting point (Tm) of 120°C or higher and 170°C or lower as measured by differential scanning calorimetry (DSC). From the viewpoint of achieving both opening properties and low-temperature heat sealability, the melting point of the specific propylene polymer (A) is preferably 121° C. to 155° C., and more preferably 130° C. to 145° C. The melting point (Tm) measured by differential scanning calorimetry (DSC) is determined under the following measurement conditions.

[0029] (Measurement conditions) The melting point (Tm) can be determined using a DSC measurement device by holding the sample at 200°C for 10 minutes, cooling it to -20°C at a rate of 10°C / min, holding it at -20°C for 1 minute, and then heating it again to 200°C at a rate of 10°C / min, as the temperature (the temperature at the apex of the melting peak).

[0030] One example of a method for adjusting the melting point of the specific propylene polymer (A) to 121° C. or higher and 170° C. or lower is to control the polymerization conditions such as the amount of monomer feed, etc. For example, in the case of polymerization using a Ziegler-Natta catalyst, the comonomer content may be controlled to less than 20 mol %, and in the case of polymerization using a metallocene catalyst, the comonomer content may be controlled to less than 10 mol %, and by these methods, a specific propylene polymer (A) having a desired melting point can be obtained.

[0031] The composition of the specific propylene polymer (A) is not particularly limited as long as it has a melting point of 121°C or higher and 170°C or lower, and examples thereof include a propylene homopolymer (hereinafter also referred to as "homoPP: hPP"), a copolymer of propylene as the main component with other ethylene and / or a random copolymer (hereinafter also referred to as "random PP: rPP"), and a block copolymer (hereinafter also referred to as "block PP: bPP"). In a propylene-based polymer containing propylene as a main component, the content of structural units derived from propylene is preferably 50 mol% or more, more preferably 80 mol% or more, and even more preferably 90 mol% or more, based on the total number of moles of all structural units constituting the propylene-based polymer.

[0032] The specific propylene polymer (A) is preferably a random copolymer obtained by copolymerizing propylene with ethylene and / or an α-olefin having from 4 to 20 carbon atoms. In order to improve the balance between blocking resistance and low-temperature heat sealability, a copolymer of propylene, ethylene and an α-olefin having from 4 to 20 carbon atoms is preferred, and a propylene-ethylene-1-butene copolymer is particularly preferred.

[0033] The specific propylene polymer (A) preferably has a melt flow rate (MFR) measured in accordance with ASTM D1238 at 230°C under a load of 2.16 kg of 0.1 to 100 g / 10 min, more preferably 0.5 to 50 g / 10 min, and even more preferably 1 to 20 g / 10 min.

[0034] The specific propylene polymer (A) can be produced by a known polymerization method, for example, a method of polymerizing a monomer in the presence of a known catalyst such as a Ziegler-Natta catalyst or a metallocene catalyst by a known polymerization method such as a gas phase method, a bulk method, or a slurry method.

[0035] The content of the specific propylene polymer (A) (the total amount when a plurality of specific propylene polymers (A) are present) is preferably 10% by mass to 90% by mass, more preferably 15% by mass to 70% by mass, even more preferably 20% by mass to 60% by mass, and particularly preferably 20% by mass to 50% by mass, based on the total mass of the composition. The specific propylene polymer (A) may be used alone or in combination of two or more kinds.

[0036] <Specific olefin polymer (B)> The specific olefin polymer (B) has a melting point (Tm) measured by differential scanning calorimetry (DSC) of 30° C. or higher and lower than 120° C. The melting point of the specific olefin polymer (B) may be 30° C. or higher and lower than 120° C., or no melting point may be observed. The specific olefin polymer (B) is not particularly limited as long as it is a polymer containing an olefin having a melting point (Tm) measured by differential scanning calorimetry (DSC) of 30° C. or higher and lower than 120° C. When the melting point of the olefin polymer (B) according to the present invention is within the above range, the polymer also has excellent low-temperature heat sealability.

[0037] Examples of the specific olefin polymer (B) include homopolymers of α-olefins and copolymers of α-olefins and monomers other than α-olefins.

[0038] Specific examples of the specific olefin polymer (B) include ethylene polymers containing ethylene as the main component, such as ethylene homopolymers and copolymers of ethylene with an α-olefin having 3 or more carbon atoms (i.e., ethylene-α-olefin copolymers) (hereinafter also referred to as "ethylene polymers (B1)"); propylene polymers containing propylene as the main component, such as copolymers of propylene with ethylene and / or an α-olefin having 4 or more carbon atoms (i.e., propylene-ethylene copolymers) (hereinafter also referred to as "propylene polymers (B2)"); 1-butene homopolymers and 1-butene polymers containing 1-butene as the main component, such as copolymers of 1-butene with ethylene, propylene, or an α-olefin having 5 or more carbon atoms (hereinafter also referred to as "1-butene polymers (B3)"); and the like.

[0039] In an ethylene-based polymer containing ethylene as the main component, the content of structural units derived from ethylene is preferably 50 mol% or more, more preferably 80 mol% or more, and more preferably 90 mol% or more, relative to the total number of moles of all structural units constituting the ethylene-based polymer. Similarly, in a propylene-based polymer containing propylene as the main component, the content of structural units derived from propylene is preferably 50 mol% or more, more preferably 60 mol% or more, and more preferably 70 mol% or more, relative to the total number of moles of all structural units constituting the propylene-based polymer. Similarly, in a 1-butene-based polymer containing 1-butene as the main component, the content of structural units derived from 1-butene is preferably 50 mol% or more, more preferably 60 mol% or more, and more preferably 70 mol% or more, relative to the total number of moles of all structural units constituting the 1-butene-based polymer.

[0040] <<Ethylene polymer (B1)>> In the ethylene polymer (B1), examples of the α-olefin having 3 or more carbon atoms to be copolymerized with ethylene include α-olefins having 3 to 20 carbon atoms, such as propylene, 1-butene, 1-pentene, 3-methyl-1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, and 1-tetradecene. Among these, 1-butene, 1-hexene, and 1-octene are preferred as the α-olefins from the viewpoint of achieving an excellent balance between strength, flexibility, and low-temperature heat-sealability improvement performance.

[0041] Specific examples of the ethylene polymer (B1) include high-pressure low-density polyethylene, linear low-density polyethylene, and ethylene-α-olefin copolymer. The α-olefin to be copolymerized with ethylene may be one kind alone or two or more kinds of α-olefins.

[0042] <<Propylene polymer (B2)>> In the propylene polymer (B2), examples of the α-olefin having 4 or more carbon atoms to be copolymerized with propylene include the α-olefins in the ethylene polymer (B1) other than propylene. The propylene polymer (B2) is preferably a propylene-ethylene copolymer, a propylene-1-butene copolymer, or a propylene-ethylene-1-butene copolymer. Among these, the propylene polymer (B2) is preferably a propylene-ethylene copolymer or a propylene-ethylene-1-butene copolymer from the viewpoint of excellent flexibility and promoting stress relaxation.

[0043] As the propylene polymer (B2), a propylene-1-butene copolymer is preferred, since it has high crystallinity even at a low melting point and is likely to provide blocking resistance. The α-olefin copolymerized with propylene may be one type, or two or more types of α-olefins including ethylene.

[0044] <<1-butene polymer (B3)>> In the 1-butene polymer (B3), examples of the α-olefin having 5 or more carbon atoms to be copolymerized with 1-butene include the α-olefins having 5 or more carbon atoms in the ethylene polymer (B1). From the viewpoint of opening property and low-temperature heat sealability, the 1-butene polymer (B3) is preferably a 1-butene-ethylene copolymer or a 1-butene-propylene copolymer.

[0045] Among these, the 1-butene polymer (B3) is preferably a 1-butene-ethylene copolymer or a 1-butene-propylene copolymer, from the viewpoints of a low melting point, excellent low-temperature heat sealability, and ease of obtaining blocking resistance. The α-olefin copolymerized with 1-butene may be one kind or two or more kinds of α-olefins including ethylene or propylene.

[0046] The content of the specific olefin polymer (B) (the total content when multiple types of specific olefin polymer (B) are present) is preferably 10% by mass to 90% by mass, more preferably 30% by mass to 85% by mass, even more preferably 40% by mass to 80% by mass, and particularly preferably 50% by mass to 80% by mass, relative to the total mass of the composition. The specific olefin polymer (B) may be contained as one type of polymer or as two or more types of copolymer, or may be a combination of a homopolymer and a copolymer.

[0047] From the viewpoint of excellent opening properties and low-temperature heat sealability, the specific olefin polymer (B) preferably contains at least one olefin polymer selected from the group consisting of ethylene polymer (B1), propylene polymer (B2), and 1-butene polymer (B3), more preferably contains at least one olefin polymer selected from the group consisting of propylene polymer (B2) and 1-butene polymer (B3), further preferably contains polymer (B2) or 1-butene polymer (B3), and particularly preferably contains a propylene-ethylene copolymer or a propylene-1-butene copolymer. When the propylene polymer (B2) or the 1-butene polymer (B3) is contained, blocking resistance is easily obtained even if the melting points of these polymers are low.

[0048] The specific olefin polymer (B) preferably has an MFR of 0.1 to 100 g / 10 min, more preferably 0.5 to 50 g / min, and even more preferably 1 to 20 g / 10 min, as measured in accordance with ASTM D1238 at 230°C under a load of 2.16 kg.

[0049] The specific olefin polymer (B) preferably has an MFR of 0.1 to 100 g / 10 min, more preferably 0.5 to 50 g / 10 min, and even more preferably 1 to 20 g / 10 min, as measured in accordance with ASTM D1238 at 190°C under a load of 2.16 kg.

[0050] From the viewpoint of opening property and low-temperature heat sealability, the olefin polymer composition according to the present invention preferably contains 10% by mass to 90% by mass of the propylene polymer (A) and 10% by mass to 90% by mass of the olefin polymer (B) relative to 100% by mass of the total amount of the propylene polymer (A) and the olefin polymer (B); more preferably contains 15% by mass to 70% by mass of the propylene polymer (A) and 30% by mass to 85% by mass of the olefin polymer (B); still more preferably contains 20% by mass to 60% by mass of the propylene polymer (A) and 50% by mass to 80% by mass of the olefin polymer (B); and particularly preferably contains 20% by mass to 50% by mass of the propylene polymer (A) and 50% by mass to 80% by mass of the olefin polymer (B). However, the total amount of the propylene polymer (A) and the olefin polymer (B) is 100% by mass.

[0051] [Additives] The olefin polymer composition of the present invention may further contain, as necessary, a nucleating agent, a heat stabilizer, an antioxidant, a weather stabilizer, an antistatic agent, a slip agent, an antifogging agent, a lubricant, a dye, a pigment, a natural oil, a synthetic oil, a wax, a filler, an antiblocking agent other than the crosslinked product of the ultrahigh molecular weight olefin polymer (C), and the like, within the scope of the object of the present invention.

[0052] Examples of nucleating agents include dibenzylidene sorbitol-based nucleating agents, phosphate ester salt-based nucleating agents, rosin-based nucleating agents, metal benzoate salt-based nucleating agents, fluorinated polyethylene, sodium 2,2-methylenebis(4,6-di-t-butylphenyl)phosphate, pimelic acid and its salts, and 2,6-naphthalene dicarboxylic acid dicyclohexylamide. The amount of the nucleating agent is not particularly limited, but is preferably about 0.1 to 1 mass % based on the total mass of the olefin polymer composition. The timing of addition is not particularly limited, and the nucleating agent may be added during or after the polymerization reaction of the specific propylene polymer (A), the specific olefin polymer (B), or the ultra-high molecular weight olefin polymer, or during film molding.

[0053] Examples of the antioxidant include known antioxidants, specifically hindered phenol compounds, sulfur-based antioxidants, lactone-based antioxidants, organic phosphite compounds, organic phosphonite compounds, and combinations of several of these.

[0054] Examples of lubricants include sodium, calcium and magnesium salts of saturated or unsaturated fatty acids such as lauric acid, palmitic acid, oleic acid and stearic acid, which may be used alone or in combination of two or more. The amount of the lubricant to be added is usually 0.1 to 3100 parts by mass, and preferably 0.1 to 2100 parts by mass, based on 100 parts by mass of the olefin polymer composition.

[0055] As the slip agent, it is preferable to use an amide of a saturated or unsaturated fatty acid such as lauric acid, palmitic acid, oleic acid, stearic acid, erucic acid, or hebenic acid, or a bisamide of these saturated or unsaturated fatty acids. Among these, erucic acid amide and ethylene bisstearamide are particularly preferable. These fatty acid amides are preferably blended in an amount of 0.01 to 100 parts by mass per 100 parts by mass of the olefin polymer composition.

[0056] [Method for producing olefin polymer composition] The olefin polymer composition according to the present invention can be obtained by mixing the above-mentioned crosslinked ultrahigh molecular weight olefin polymer (C), the specific propylene polymer (A) and the specific olefin polymer (B), and further mixing, if necessary, the additives described below.

[0057] Various known methods can be used to mix the components, including, for example, a multistage polymerization method, a method of mixing using a plastomill, a Henschel mixer, a V-blender, a ribbon blender, a tumbler, a blender, a kneader-ruder, etc., or a method of mixing, then melt-kneading, and then granulating or pulverizing using a single-screw extruder, a twin-screw extruder, a kneader, a Banbury mixer, etc. These methods can provide a high-quality olefin polymer composition in which the components and additives are uniformly dispersed and mixed.

[0058] The shape of the olefin polymer composition is not particularly limited, and examples thereof include pellets, sheets, strands, chips, etc. Furthermore, the crosslinked ultra-high molecular weight olefin polymer (C), the specific propylene polymer (A), and the specific olefin polymer (B) contained in the olefin polymer composition may be melt-kneaded and then directly molded into a molded article.

[0059] (sealant film) The sealant film according to the present invention preferably contains a layer formed from the above-mentioned olefin polymer composition. The method for forming the layer from the olefin polymer composition is not particularly limited, and any known forming method can be used. For example, the olefin polymer composition and, if necessary, additives and the like can be mixed and heated to melt, and then the layer can be formed from the olefin polymer composition using an extrusion molding machine, an inflation molding machine or the like.

[0060] The sealant film may be a non-stretched film or a stretched film. When the sealant film is a non-stretched film, the non-stretched sealant film can be formed using the above-mentioned olefin polymer composition using, for example, a commonly used known film forming machine such as a cast molding machine or an inflation molding machine.

[0061] When the sealant film is a stretched film, the olefin polymer composition may be used to form a film, and then the film formed from the olefin polymer composition may be stretched. When the sealant film is a stretched film, it has excellent stiffness (rigidity).

[0062] The sealant film can be stretched by any known method for producing stretched films, such as roll stretching, tenter stretching, tubular stretching, or a combination of these stretching methods. The stretching (area) ratio is preferably 1.5 to 50 times, and more preferably 2 to 40 times.

[0063] From the viewpoint of excellent low-temperature heat sealability, the heat seal strength of the sealant film is preferably such that the maximum heat seal strength in the temperature range of 70°C or higher and 80°C or lower is 8 N / 15 mm or higher, or the maximum heat seal strength in the temperature range of 70°C or higher and 80°C or lower is less than 8 N / 15 mm and the maximum heat seal strength in the temperature range of more than 80°C and 100°C or lower is 8 N / 15 mm or higher, and more preferably such that the maximum heat seal strength in the temperature range of 70°C or higher and 80°C or lower is 10 N / 15 mm or higher, or the maximum heat seal strength in the temperature range of 70°C or higher and 80°C or lower is less than 10 N / 15 mm and the maximum heat seal strength in the temperature range of more than 80°C and 100°C or lower is 10 N / 15 mm or higher.

[0064] The thickness of the sealant film (hereinafter sometimes referred to as "sealant layer thickness") is preferably 0.1 to 50 μm, more preferably 0.3 to 40 μm, and even more preferably 0.5 to 25 μm. In the case of a laminate having a plurality of sealant films, it is preferable that each sealant film has the above thickness.

[0065] The total thickness of the sealant film is preferably 50% or less of the total thickness including the substrate layer described below, more preferably 40% or less, even more preferably 35% or less, and particularly preferably 20% or less, which brings the laminate closer to a single material mainly composed of the substrate layer, and has the advantage of facilitating recycling.

[0066] -Base film- The sealant film may be a sealant film with a base film, which is provided with a base film described below to support the sealant film. In the case of a sealant film with a base film, the base film is preferably a polypropylene film.

[0067] Examples of polypropylene constituting the polypropylene film include propylene homopolymers and copolymers containing propylene as the main monomer. In the case of copolymers, they may be random copolymers or block copolymers. Examples of monomers copolymerizable with propylene include α-olefins other than propylene and diene compounds. The propylene content (structural units derived from propylene) in the polypropylene is preferably 85 to 100 mol%, more preferably 90 to 99.5 mol%. The content of other monomers other than propylene is preferably 0 to 15 mol%, more preferably 0.5 to 10 mol%.

[0068] Examples of α-olefins other than propylene that can be copolymerized with propylene include α-olefins having 2 or 4 to 20 carbon atoms, such as ethylene, 1-butene, 1-pentene, 3-methyl-1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, and 1-tetradecene.

[0069] Specific examples of polypropylene include propylene homopolymer, propylene-ethylene random copolymer, propylene-1-butene random copolymer, propylene-1-butene-ethylene random copolymer, propylene-1-hexene random copolymer, propylene-3-methyl-1-butene random copolymer, and propylene-4-methyl-1-pentene random copolymer. The polypropylene may be used alone or in combination of two or more kinds.

[0070] The polypropylene used for the substrate film may be the same polymer as the specific propylene polymer (A) contained in the olefin polymer composition and / or the propylene polymer (B2).

[0071] The MFR of the polypropylene, measured in accordance with ASTM D1238 at 230° C. under a load of 2.16 kg, is preferably 0.1 to 10 g / 10 min, and more preferably 0.5 to 8 g / 10 min. The melting point (Tm) of the polypropylene is preferably 120 to 165°C, and more preferably 135 to 150°C.

[0072] The method for producing polypropylene is not particularly limited, and known production methods can be used, such as a production method in which monomers are polymerized in the presence of a known catalyst such as a Ziegler-Natta catalyst or a metallocene catalyst by a known polymerization method such as a gas phase method, a bulk method, or a slurry method.

[0073] The base film is preferably thicker than the sealant film, since the laminate of the base film and the sealant film is closer to a single material, which has the advantage of facilitating recycling. The total thickness of the base film is usually preferably 50% or more, more preferably 60% or more, even more preferably 75% or more, and particularly preferably 80% or more, of the total thickness of the laminate. The thickness of the substrate film is preferably 10 to 200 μm, more preferably 11 to 100 μm, and even more preferably 12 to 50 μm.

[0074] The base film is preferably at least one selected from unstretched polypropylene films (CPP films) obtained by not stretching a film formed from the above polypropylene, and biaxially stretched polypropylene films (OPP films) obtained by biaxially stretching the film. As the stretching method, a known method for producing a stretched film can be used, and specifically, the above-mentioned method for stretching the sealant film can be mentioned, and the same applies to the preferred embodiments.

[0075] The base film may contain additives as needed, and examples of the additives include the additives in the sealant film described above. The substrate film may consist of one layer or multiple layers.

[0076] The sealant film may further contain layers other than the base film (hereinafter referred to as "other layers") to impart specific functions. Examples of the other layers include functional material layers such as a printed layer, a barrier layer, and an embossed layer.

[0077] Examples of the functional material layer include a resin film on which an inorganic compound or an inorganic oxide is vapor-deposited, a metal foil, a coated film of a resin having a special function, and a resin film on which a pattern is printed.

[0078] Examples of the sealant film include, but are not limited to, a two-layer structure of sealant film / substrate film, and a three-layer structure of sealant film / substrate film / sealant film. An adhesive layer may be provided between the sealant film and the base film.

[0079] When the sealant film includes a base film, the sealant film and the base film may be laminated by coextrusion, or may be laminated by a general lamination method such as extrusion lamination or dry lamination. The sealant film and the base film may be co-extruded and then further laminated with a base film.

[0080] When the sealant film has a base film, it may be manufactured by laminating the sealant film and the base film via an adhesive layer using dry lamination, non-solvent lamination, sand lamination, etc., or it may be manufactured by laminating the sealant film and the base film by melt extrusion lamination. Among these, the lamination method by dry lamination or melt extrusion lamination is preferable.

[0081] The sealant film produced by the above method may be stretched. As the stretching method, a known method for producing a stretched film can be used. Specific stretching methods include the stretching methods for the sealant film described above, and the preferred stretching (area) ratios are also the same.

[0082] Because of its excellent low-temperature heat-sealing properties, the sealant film can be used to produce a container by placing the sealant film surfaces face to face, or by placing the heat-sealable layer of the sealant film of a laminate film face to face with another film, and then heat-sealing at least a portion of the periphery from the outer surface side to form a desired container shape. Furthermore, by heat-sealing the entire periphery, a sealed bag-like container can be produced. By combining the molding process of this bag-like container with a filling process, i.e., by heat-sealing the bottom and sides of the bag-like container, filling it with contents, and then heat-sealing the top, a package can be produced. This package can be used in automatic packaging equipment for solid foods such as snacks and bread, powders, or liquid ingredients.

[0083] Alternatively, a container containing the contents can be obtained by filling a container, such as one in which the sealant film has been formed into a cup shape by vacuum forming or pressure forming, a container obtained by injection molding, or a container formed from a paper substrate, and then covering the container with the sealant film as a lid and heat-sealing the top or side of the container. This container is suitable for packaging instant noodles, miso paste, jelly, pudding, snacks, etc.

[0084] (unstretched film) From the viewpoint of achieving both easy opening and low-temperature heat sealing properties, the non-oriented film according to the present invention more preferably contains a layer formed from the above-mentioned olefin polymer composition. The thickness of the unstretched film varies depending on the application, but is usually preferably 10 to 100 μm, and more preferably 20 to 80 μm.

[0085] The method for forming the unstretched film is not particularly limited, and examples thereof include a method of extrusion molding the olefin polymer composition, or a method of forming the unstretched film using a known film forming machine such as a commonly used cast molding machine or inflation molding machine.

[0086] From the viewpoint of achieving both easy opening and low-temperature heat sealing properties, the unstretched film can be used in a wide range of packaging fields, such as packaging fresh foods such as vegetables and fish meat; packaging various foods such as snacks, dried foods such as noodles, and watery foods such as soups and pickles; packaging medical-related products such as medical products in various forms such as tablets, powders, and liquids, and medical peripheral materials; and packaging various electrical equipment such as cassette tapes and electrical components.

[0087] (Blown film) The inflation film according to the present invention preferably contains a layer formed from the olefin polymer composition, from the viewpoints of being able to be stably molded during inflation film molding and being excellent in opening properties and low-temperature heat sealability. The inflation film may be a single layer film formed from the above olefin polymer composition, or may be a multilayer film with a polymer other than the above olefin polymer. The blown film can exhibit better opening properties and low-temperature heat sealability, particularly in air-cooled blown film molding.

[0088] The inflation film can be produced by extruding the olefin polymer composition into an inflation film using, for example, an inflation film extruding machine.

[0089] The conditions for air-cooled inflation film molding are not particularly limited, but the molding temperature is preferably equal to or higher than the melting point of the raw material resin used and lower than 300°C. The expansion ratio is preferably 1.1 to 5.0, and more preferably 1.2 to 4.5. The expansion ratio refers to the ratio of the maximum bubble diameter to the die diameter. The take-up speed is determined by the film thickness, width, and extrusion rate, and can be adjusted within a range that maintains film formation stability. In general, the take-up speed is preferably 1 to 150 m / min, and more preferably 1 to 100 m / min.

[0090] The thickness of the inflation film varies depending on the application, but is usually preferably 10 to 100 μm, more preferably 20 to 80 μm.

[0091] Suitable uses of inflation films include, for example, materials for packaging daily necessities, food packaging, food containers, retort containers, protective films, decorative films and sheets, shrink films, infusion bags, heat-sealing films, stretched films, raw film for stretching, and medical containers. [Example]

[0092] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. The physical properties shown in the examples were measured by the following methods.

[0093] <Propylene polymer (A)> rPP-1 (A-1): Random polypropylene (MFR (230°C, 2.16 kg load, based on ASTM D1238): 7 g / 10 min, melting point measured by differential scanning calorimetry (DSC): 138°C, propylene content: 96 mol%) rPP-2 (A-2): Random polypropylene (MFR (230°C, 2.16 kg load, based on ASTM D1238): 2.2 g / 10 min, melting point measured by differential scanning calorimetry (DSC): 133°C, propylene content: 95 mol%)

[0094] <Olefin polymer (B)> BPR (B3-1): 1-butene-propylene copolymer (MFR (230°C, 2.16 kg load, ASTM D1238): 9 g / 10 min, MFR (190°C, 2.16 kg load, ASTM D1238): 4 g / 10 min, melting point measured by differential scanning calorimetry (DSC): 100°C, 1-butene content: 87 mol%, propylene content: 13 mol%) PER (B2-1): Propylene-ethylene copolymer (MFR (230°C, 2.16 kg load, ASTM D1238): 8 g / 10 min, MFR (190°C, 2.16 kg load, ASTM D1238): 3.7 g / 10 min, melting point measured by differential scanning calorimetry (DSC): 75°C, propylene content: 87 mol%, ethylene content: 13 mol%) The melting points of the propylene polymer (A) and the olefin polymer (B) measured by differential scanning calorimetry (DSC) were measured according to the above-mentioned method and conditions for differential scanning calorimetry (DSC).

[0095] <Crosslinked Ultra-High Molecular Weight Olefin Polymer (C)> Ultra-high molecular weight polyethylene fine particles (Mitsui Chemicals, Inc., Mipelon® PM-200, intrinsic viscosity [η] = 13.0 dl / g, MFR (190°C, 21.6 kg load) = 0.020 g / 10 min, average particle diameter d 50 = 10.5 μm, sieve passing rate of 37 μm mesh > 99% by mass was irradiated with an electron beam at an irradiation dose of 200 kGy to obtain a crosslinked ultra-high molecular weight polyethylene polymer (C-1).

[0096] <Method for measuring heat seal strength (HS strength)> The heat seal strength was measured by the following method. A sealant film was prepared by overlapping two of the sealant films with the substrate films obtained below so that the sealant film surfaces faced each other. The lower seal bar was set to 70°C, and the upper seal bar was set to 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C or 160°C. Heat sealing was performed at each of the above temperatures with a seal bar width of 5 mm at a pressure of 0.2 MPa for 1 second, and then allowed to cool. Next, a 15 mm width of the heat-sealed sealant film was cut out from the heat-sealed sealant film so as to include the heat-sealed portion at each temperature, and used as a test specimen. For each test specimen heat-sealed at each temperature, the heat-sealed portion was peeled off in a 180° direction at a crosshead speed of 300 mm / min, and the peel strength (N / 15 mm) was measured. The obtained values ​​were evaluated according to the following evaluation criteria. Evaluation criteria of "A" and "B" indicate excellent low-temperature heat-sealability.

[0097] -Evaluation criteria: [Low temperature heat sealability]- "A" indicates that the maximum heat seal strength in the temperature range of 70℃ to 80℃ is 8N / 15mm or more. "B" indicates that the maximum heat seal strength in the temperature range of 70°C to 80°C is less than 8N / 15mm, and that the maximum heat seal strength in the temperature range of more than 80°C to 100°C is 8N / 15mm or more. "C" indicates that the maximum heat seal strength in the temperature range of 70°C to 100°C is less than 8N / 15mm, and that the maximum heat seal strength in the temperature range of more than 100°C to 120°C is 8N / 15mm or more. Those whose maximum heat seal strength in the temperature range of 70°C or higher but less than 120°C was less than 8N / 15mm were rated "D".

[0098] <Method for measuring blocking force> The sealant film obtained below was cut into 200 mm wide strips, and two strips of film were overlapped with the sealant surfaces facing each other. The two strips were placed in an air oven at 50°C, and a 20 kg load was applied to the overlapping strips, allowing them to cure for three days. The strips were then removed from the air oven, and the blocking force was measured when the two strips were peeled at a 180° angle at a speed of 200 mm / min, and evaluated according to the following criteria. Note that the smaller the measured blocking force, the better the blocking resistance.

[0099] -Evaluation criteria:- "A": No blocking confirmed. "B": The blocking force is greater than 0 N / m and less than 10 N / m. "C": The blocking force is 10 N / m or more and less than 100 N / m. "D": Blocking force is 100 N / m or more.

[0100] <Method for evaluating opening properties> The opening property was measured by the following method: An inflation film was produced using an inflation molding machine at a molding speed of 7, 10, 13, 16, or 20 m / min, with the resin composition for a sealant film prepared below on the inner surface (hereinafter also referred to as the "sealant inner surface") and the resin rPP-2 for the base layer on the outer surface. Cellophane tape was then attached to each outer surface of the film, and the two surfaces with the cellophane tape attached were peeled off in a 180° direction to check for adhesion between the inner surfaces of the sealants. The opening property was evaluated according to the following evaluation criteria.

[0101] -Evaluation criteria for opening ability- "A": Peeling between the inner surfaces of the sealant was confirmed when the take-up speed of the take-up roll in the inflation molding machine was 20 m / min. "B": No peeling was observed between the inner surfaces of the sealant when the take-up speed of the take-up roll in the inflation molding machine was 20 m / min.

[0102] Example 1 A resin composition for a sealant film (olefin polymer resin composition) was prepared by blending 40 parts by weight of rPP-1 (A-1), 60 parts by weight of BPR (B3-1), and 600 ppm of ultra-high molecular weight polyethylene (C-1) per 100 parts by weight of the total of (A-1) and (B-1). Also, rPP-2 (A-2) was prepared for preparing a substrate film. Using two extruders connected to a T-die, the above-mentioned resin composition for the sealant film and rPP-2 for preparing the base film were fed into each extruder. The die and resin temperatures were set to 230°C, and the extrusion rate of each extruder was adjusted to obtain a non-stretched sealant film with a base film, consisting of a 50 μm-thick non-stretched base film and a 20 μm-thick non-stretched sealant film laminated together. The heat seal strength of the resulting non-stretched sealant film was measured using the heat seal strength measurement method described above. The blocking force was also measured using the blocking force measurement method described above. The results are shown in Table 1.

[0103] (Examples 2 and 3 and Comparative Examples 1 to 4) In Examples 2 and 3, unstretched sealant films were produced in the same manner as in Example 1, except that the composition of the resin composition for sealant films was changed to the composition shown in Table 1. In Comparative Examples 1 to 4, unstretched sealant films were produced in the same manner as in Example 1, except that the crosslinked product (C-1) of the ultra-high molecular weight ethylene polymer in Example 1 was changed to silica (average particle size 3 μm) and the composition of the resin composition for sealant films was changed to the composition shown in Table 1. The heat seal strength and blocking force of each of the obtained films were measured using the measurement methods described above. The results are shown in Table 1.

[0104] Example 4 A resin composition for sealant films (olefin polymer resin composition) was prepared by blending 40 parts by mass of rPP-1 (A-1), 60 parts by mass of BPR (B3-1), and 4800 ppm of ultra-high molecular weight polyethylene (C-1) with a total of 100 parts by mass of the above (A-1) and (B-1). A resin: rPP-2 (A-2) was also prepared for the production of substrate films. The sealant resin composition was fed into each extruder so that it was on the inner surface and the base layer resin (rPP-2) was on the outer surface. Using an inflation die (die diameter 200 mmφ, lip gap 3.5 mm), the resin temperature was set to 200°C, and the extrusion rates of each extruder were adjusted so that the thicknesses of the heat seal layer formed from the sealant film resin composition and the base layer (the base film) were 20 μm and 50 μm, respectively, at a molding speed of 7 m / min. A 70 μm-thick inflation film was obtained by co-extrusion molding. The heat seal strength of this film was measured using the heat seal strength measurement method described above. The results are shown in Table 2. Furthermore, while keeping the resin extrusion rate constant, the take-up speed of the take-up roll was increased to 10, 13, 16, or 20 m / min. Following the same method for evaluating opening properties as above, cellophane tape was applied to the outer surface of each film obtained at a take-up speed of 20 m / min. The cellophane tape was then peeled off to check for adhesion between the inner surfaces of the sealant films, and the opening properties were evaluated according to the evaluation criteria described above. The results are shown in Table 2.

[0105] (Comparative Examples 5 and 6) Blown films were produced in the same manner as in Example 4, except that the ultra-high molecular weight polyethylene was replaced with silica (average particle diameter 3 μm) as the antiblocking agent, or no antiblocking agent was added. The heat seal strength and blocking force of the resulting blown films were measured using the above-mentioned measurement methods. The opening properties were also evaluated according to the above-mentioned evaluation criteria. The results are shown in Table 2.

[0106] (Comparative Example 7) An inflation film was produced in the same manner as in Example 4, except that the composition of the resin composition for a sealant film was changed to the composition shown in Table 2. The heat seal strength and blocking force of the obtained inflation film were measured using the above-mentioned measurement methods. The opening property was also evaluated according to the above-mentioned evaluation criteria. The respective results are shown in Table 2.

[0107] [Table 1]

[0108] [Table 2]

[0109] In Tables 1 and 2, the "Sealing initiation temperature (≧8N / 15mm)" column indicates the lowest heat-sealing temperature at which the heat-sealing strength is 8N / 15mm or more. For example, the "80" in the "Sealing initiation temperature (≧8N / 15mm)" column in Example 1 indicates that 80°C is the lowest heat-sealing temperature between 80°C and 120°C at which the heat-sealing strength is 8N / 15mm or more. In addition, "-" in Tables 1 and 2 means that there is no corresponding value or that it could not be measured. In Table 2, the blocking force result "no adhesion" means that no blocking was observed.

[0110] It is clear that the films of Examples 1 to 3 obtained from the olefin polymer compositions according to the present invention are superior in both blocking resistance and low-temperature heat sealability compared to the films of Comparative Examples 1 to 4. It is also clear that the inflation film of Example 4 according to the present invention is superior in both opening property and low-temperature heat sealability compared to the inflation films of Comparative Examples 5 to 7.

Claims

1. a propylene polymer (A) having a melting point (Tm) measured by differential scanning calorimetry (DSC) of 120°C or higher and 170°C or lower; An olefin polymer (B) having a melting point (Tm) measured by differential scanning calorimetry (DSC) of 30°C or higher and lower than 120°C, and The present invention comprises a crosslinked ultra-high molecular weight olefin polymer (C) that satisfies the following requirements (C-i) to (C-iii): When the total amount of the propylene polymer (A) and the olefin polymer (B) is taken as 100% by mass, the content of the propylene polymer (A) is 20% by mass to 50% by mass, and the content of the olefin polymer (B) is 50% by mass to 80% by mass, an olefin polymer composition, wherein the content of the crosslinked product (C) of the ultra-high molecular weight olefin polymer is 100 ppm (parts per million) to 10,000 ppm, relative to 100 parts by mass in total of the propylene polymer (A) and the olefin polymer (B). (C-i) Intrinsic viscosity [η] measured in decalin solvent at 135°C is 5 dl / g to 50 dl / g (C-ii) Average particle diameter d ５０ However, 3 μm to 30 μm (C-iii) 95% by mass or more of the material passes through a 37 μm mesh sieve

2. 2. The olefin polymer composition according to claim 1, wherein the olefin polymer (B) comprises at least one olefin polymer selected from the group consisting of an ethylene polymer (B1), a propylene polymer (B2), and a 1-butene polymer (B3).

3. The olefin polymer composition according to claim 1 or 2, wherein the ultra-high molecular weight olefin polymer is an ultra-high molecular weight ethylene polymer.

4. A sealant film comprising a layer formed from the olefin polymer composition according to any one of claims 1 to 3.

5. An unstretched film comprising the olefin polymer composition according to any one of claims 1 to 3.

6. An inflation film comprising the olefin polymer composition according to any one of claims 1 to 3.

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