JPWO2019189359A1 - Easy-to-cut multilayer film with high surface hardness - Google Patents

Abstract

An object of the present invention is to provide a multilayer film having appropriate rigidity without curling by improving the surface hardness of the film while maintaining transparency, heat sealability, impact strength and tensile elastic modulus. To do. The multilayer film of the present invention contains 0.1 to 10% by weight of the cyclic olefin resin (a1) and 90 to 99.9% by weight of the ethylene resin (b1) satisfying the following conditions (i) and (ii). A layer (I) composed of the resin composition to be used, 10 to 70% by weight of the cyclic olefin resin (a2), and 30 to 90% by weight of the ethylene resin (b2) satisfying the following conditions (i) and (ii). The layer (II) composed of the resin composition contained and the layer (III) containing the ethylene resin (b3) are included: (i) the density is 880 to 970 kg / m3; (ii) 190 ° C., 2 The melt mass flow rate (MFR) under a load of .16 kg is 0.1 to 50 g / 10 minutes.

Description

The present invention relates to a multilayer film having easy-cut property, high surface hardness, and suitable for packaging applications.

Inflation films made of polyethylene are widely used in packaging applications and are heat-sealed to seal the packaging bag.

Such packaging films are required to have characteristics according to their uses. For example, the package is required to be easily torn and opened (easily cut) so that the package can be torn and opened by hand (see, for example, Patent Document 1). Further, in the case of a heavy-duty packaging bag, it is required to have a strength that does not tear even if grains or fertilizers of several tens of kilograms are put in, and therefore a strong dirt impact strength is required (see, for example, Patent Document 2). Further, if the film itself is not rigid at the time of filling, the film may be broken and wrinkled, or the device may be caught and scratched, so that appropriate rigidity is required. However, if the rigidity is high, the dart impact strength is weakened, which causes problems such as the film being torn and the contents being spilled, and the transparency being deteriorated and the contents being difficult to see.

In order to impart appropriate rigidity (surface hardness), a method of using high-density polyethylene or polypropylene having a higher rigidity than the intermediate layer is used for the surface layer of the packaging film, but in this case, the curl is severe and the curl is severe. There is a problem that makes bag making difficult.

Therefore, there has been a demand for a film that does not curl, has sufficient rigidity (surface hardness) at the time of filling, and has high impact strength.

Japanese Unexamined Patent Publication No. 10-237234 Japanese Unexamined Patent Publication No. 2016-049775

An object of the present invention is to improve the surface hardness of a film while maintaining transparency, heat sealability, impact strength and tensile elastic modulus in view of the above-mentioned problems of the prior art, thereby preventing curling. It is an object of the present invention to provide a multilayer film having an appropriate rigidity.

The present inventors have diligently studied to solve the above problems. As a result, we found that by blending a cyclic olefin resin in a specific amount on the surface layer of a polyethylene multilayer film, it is possible to increase the surface hardness while maintaining excellent properties of impact strength and tensile elastic modulus. The invention was completed. In the prior arts such as Patent Documents 1 and 2, there was a technical idea that a cyclic olefin resin was blended in the intermediate layer of the multilayer film to obtain easy cutting property, but a specific amount was applied to the surface layer of the multilayer film. There was no technical idea to improve the surface hardness by blending the cyclic olefin resin of. Examples of aspects of the present invention are shown below.

[1] A resin composition containing 0.1 to 10% by weight of a cyclic olefin resin (a1) and 90 to 99.9% by weight of an ethylene resin (b1) satisfying the following conditions (i) and (ii). (However, the total of the component (a1) and the component (b1) is 100% by weight.) The layer (I) composed of
A resin composition containing 10 to 70% by weight of the cyclic olefin resin (a2) and 30 to 90% by weight of the ethylene resin (b2) satisfying the following conditions (i) and (ii) (however, the component (a2)). And the component (b2) are 100% by weight.) And the layer (II).
Multilayer film containing a layer (III) containing an ethylene resin (b3):
(I) The density is 880-970 kg / m ³ ;
(Ii) The melt mass flow rate (MFR) at 190 ° C. and a load of 2.16 kg is 0.1 to 50 g / 10 minutes.

[2] The multilayer film according to Item [1], wherein the cyclic olefin resins (a1) and (a2) are ethylene / cyclic olefin copolymers.

[3] Cyclic olefin resin (a3) 0 to 70% by weight is provided between the layer (I) and the layer (II) and at least one between the layer (II) and the layer (III). , A resin composition containing 30 to 100% by weight of an ethylene resin (b4) satisfying the above conditions (i) and (ii) (however, the total of the component (a3) and the component (b4) is 100% by weight. The multilayer film according to Item [1] or [2], further comprising a layer (IV) composed of.).

[4] The multilayer according to Item [3], wherein the total usage ratio of the cyclic olefin resins (a1), (a2) and (a3) with respect to the entire film is 0.1 to 60% by weight. the film.

According to the present invention, it is possible to provide a multilayer film for packaging in which the surface hardness of the film is improved without causing curl while maintaining transparency, heat sealability, impact strength and tensile elastic modulus.

Hereinafter, the multilayer film according to the present invention will be described in detail.

The multilayer film according to the present invention is
A resin composition containing 0.1 to 10% by weight of the cyclic olefin resin (a1) and 90 to 99.9% by weight of the ethylene resin (b1) satisfying the following conditions (i) and (ii). The total of the component (a1) and the component (b1) is 100% by weight), and the layer (I).
A resin composition containing 10 to 70% by weight of the cyclic olefin resin (a2) and 30 to 90% by weight of the ethylene resin (b2) satisfying the following conditions (i) and (ii) (however, the component (a2)). And the component (b2) are 100% by weight.) And the layer (II).
It is characterized by containing a layer (III) containing an ethylene resin (b3).
(I) The density is 880 to 970 kg / m ³ .
(Ii) The melt mass flow rate (MFR) at 190 ° C. and a load of 2.16 kg is 0.1 to 50 g / 10 minutes.

In addition, the multilayer film according to the present invention has a cyclic olefin resin (a3) in at least one of the layers (I) and the layer (II) and between the layer (II) and the layer (III). ) Of a resin composition containing 0 to 70% by weight and 30 to 100% by weight of an ethylene resin (b4) satisfying the above conditions (i) and (ii) (provided that the component (a3) and the component (b4) A layer (IV) consisting of 100% by weight in total) may be further included.

[Layer (I)]
The layer (I) in the multilayer film of the present invention is 0.1 to 10% by weight, preferably 0.5 to 9% by weight, more preferably 0.8 to 8% by weight of the cyclic olefin resin (a1). A resin containing 90 to 99.9% by weight, preferably 91 to 99.5% by weight, more preferably 92 to 99.2% by weight of an ethylene resin (b1) satisfying the above conditions (i) and (ii). It is composed of a composition (provided that the total of the component (a1) and the component (b1) is 100% by weight, hereinafter also referred to as "resin composition (I)").

The layer (I) serves as a surface layer of the multilayer film of the present invention. In this way, by including the cyclic olefin resin (a1) in the surface layer of the multilayer film in the above range, the film is not curled while maintaining transparency, heat sealability, impact strength and tensile elastic modulus. The surface hardness of the film can be improved.

<Cyclic olefin resin (a1)>
Examples of the cyclic olefin resin (a1) used for the layer (I) include norbornene-based polymers, vinyl alicyclic hydrocarbon polymers, and cyclic conjugated diene polymers. Among these, norbornene-based polymers are preferable. Further, as the norbornene-based polymer, a ring-opening polymer of a norbornene-based monomer (hereinafter, also referred to as “COP”), a norbornene-based copolymer obtained by copolymerizing a norbornene-based monomer and an α-olefin such as ethylene is used. (Hereinafter, also referred to as "COC") and the like. Also, hydrogenated COP and COC can be used. In the present invention, the cyclic olefin resin (a1) is preferably COC because of its dispersibility in polyethylene.

Examples of the COC include a copolymer of ethylene and a cyclic olefin represented by the following general formula (1).

式（１）中、ｎは０または正の整数であり、Ｒ¹〜Ｒ¹²は、それぞれ独立に、水素原子、ハロゲン原子または炭化水素基である。前記ハロゲン原子としては、フッ素原子、塩素原子、臭素原子またはヨウ素原子が挙げられる。

In formula (1), n is 0 or a positive integer, and R ^{1 to} R ¹² are independently hydrogen atoms, halogen atoms or hydrocarbon groups, respectively. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom.

Examples of the hydrocarbon group include an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 15 carbon atoms, and an aromatic hydrocarbon group. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a pentyl group, a hexyl group, an octyl group, a decyl group, a dodecyl group and an octadecyl group. Examples of the group include a cyclohexyl group, and examples of the aromatic hydrocarbon group include a phenyl group and a naphthyl group. These hydrocarbon groups may be substituted with halogen atoms.

Further, R ⁹ and R ¹⁰ and R ¹¹ and R ¹² may be integrated to form a divalent hydrocarbon group, and R ⁹ or R ¹⁰ and R ¹¹ or R ¹² form a ring with each other. May be good. Examples of the divalent hydrocarbon group include an alkylidene group such as an ethylidene group, a propylidene group and an isopropylidene group. The ^{ring formed from R 9} or R ¹⁰ and R ¹¹ or R ¹² may be a monocyclic ring, a condensed polycyclic ring, a polycyclic ring having a crosslink, or a ring having an unsaturated bond. It may be a ring composed of a combination of these rings.

The cyclic olefin represented by the formula (1) can be easily produced by condensing cyclopentadienes with corresponding olefins or cyclic olefins by a Diels-Alder reaction.

Specific examples of the cyclic olefin represented by the formula (1) include bicyclo [2.2.1] hept-2-ene, 6-methylbicyclo [2.2.1] hept-2-ene, 5, 6-Dimethylbicyclo [2.2.1] hept-2-ene, 1-methylbicyclo [2.2.1] hept-2-ene, 6-ethylbicyclo [2.2.1] hept-2-ene , 6-Butylbicyclo [2.2.1] hept-2-ene, 6-isobutylbicyclo [2.2.1] hept-2-ene, 7-methylbicyclo [2.2.1] hept-2-en En, tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene, 8-methyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene, 8-ethyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene, 8-propyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene, 8-hexyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene, 8-stearyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene, 8,9-dimethyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene, 8-methyl-9-ethyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene, 8-chlorotetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene, 8-promotetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene, 8-fluorotetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene, 8,9-dichlorotetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene, 8-cyclohexyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene, 8-isobutyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene, 8-butyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene, 8-ethylidenetetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene, 8-ethylidene-9-methyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene, 8-ethylidene-9-ethyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene, 8-ethylidene-9-isopropyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene, 8-ethylidene-9-butyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene, 8-n-propyridene tetracyclyl [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene, 8-n-propylidene-9-methyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene, 8-n-propylidene-9-ethyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene, 8-n-propylidene-9-isopropyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene, 8-n-propylidene-9-butyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene, 8-isopropyridene tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene, 8-isopropylidene-9-methyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene, 8-isopropylidene-9-ethyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene, 8-isopropylidene-9-isopropyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene, 8-isopropidene-9-butyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene, 5,10-dimethyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene, 2,10-dimethyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene, 11,12-dimethyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene, 2,7,9-trimethyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene, 9-ethyl-2,7-dimethyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene, 9-isobutyl-2,7-dimethyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene, 9,11,12-trimethyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene, 9-ethyl-11,12-dimethyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene, 9-isobutyl-11,12-dimethyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene, 5,8,9,10-tetramethyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene, hexacyclo [6.6.1.1 ^3,6 . 1 ^10,13 . 0 ^2,7 . 0 ^9,14] -4 Peputadesen, 12-methyl hexa cyclo [6.6.1.1 ^{3, 6.} 1 ^10,13 . 0 ^2,7 . 0 ^9,14] -4-heptadecene, 12-ethylhexanoate cyclo [6.6.1.1 ^{3, 6.} 1 ^10,13 . 0 ^2,7 . 0 ^9,14] -4-heptadecene, 12-isobutyl hexamethylene cyclo [6.6.1.1 ^{3, 6.} 1 ^10,13 . 0 ^2,7 . 0 ^9,14] -4-heptadecene, 1,6,10- trimethyl-12-isobutyl hexamethylene cyclo [6.6.1.1 ^{3, 6.} 1 ^10,13 . 0 ^2,7 . 0 ^9,14] -4-heptadecene, octacyclo [8.8.0.1 ^2,9. 1 ^4,7 . 1 ^11,18 . 1 ^13,16 . 0 ^3,8 . 0 ^12,17 ] -5-docosen, 15-methyloctacyclo [8.8.0.1 ^2,9 . 1 ^4,7 . 1 ^11,18 . 1 ^13,16 . 0 ^3,8 . 0 ^12,17 ] -5-docosen, 15-ethyloctacyclo [8.8.0.1 ^2,9 . 1 ^4,7 . 1 ^11,18 . 1 ^13,16 . 0 ^3,8 . 0 ^12,17 ] -5-docosen, pentacyclo [6.6.1.1 ^3,6 . 0 ^2,7 . 0 ^9,14 ] -4-hexadecene, 1,3-dimethylpentacyclo [6.6.1.1 ^3,6 . 0 ^2,7 . 0 ^9,14 ] -4-hexadecene, 1,6-dimethylpentacyclo [6.6.1.1 ^3,6 . 0 ^2,7 . 0 ^9,14 ] -4-hexadecene, 15,16-dimethylpentacyclo [6.6.1.1 ^3,6 . 0 ^2,7 . 0 ^9,14 ] -4-hexadecene, pentacyclo [6.5.1.1 ^3,6 . 0 ^2,7 . 0 ^9,13 ] -4-pentadecene, 1,3-dimethylpentacyclo [6.5.1.1 ^3,6 . 0 ^2,7 . 0 ^9,13 ] -4-pentadecene, 1,6-dimethylpentacyclo [6.5.1.1 ^3,6 . 0 ^2,7 . 0 ^9,13 ] -4-pentadecene, 14,15-dimethylpentacyclo [6.5.1.1 ^3,6 . 0 ^2,7 . 0 ^9,13] -4-pentadecene, pentacyclo [8.7.0.1 ^2,9. 1 ^4,7 . 1 ^11,17 . 0 ^3,8 . 0 ^12,16 ] -5-eikosen, heptacyclo [8.8.0.1 ^2,9 . 1 ^4,7 . 1 ^11,18 . 0 ^3,8 . 0 ^12,17 ] -5-heneikosen, tricyclo [4.3.0.1 ^2,5 ] -3,7-decadien, tricyclo [4.3.0.1 ^2,5 ] -3-decene, 2- Methyltricyclo [4.3.0.1 ^2,5 ] -3-decene, 5-methyltricyclo [4.3.0.1 ^2,5 ] -3-decene, tricyclo [4.4.0.0. 1 ^2,5 ] -3-undecene, 10-methyltricyclo [4.4.0.1 ^2,5 ] -3-undecene, tetracyclo [6.5.1 ^2,5 . 0 ^1,6 . 0 ^8,13] -3,8,10,12- tridecafluoro tetra-ene, tetracyclo [6.6.1 ^2,5. 0 ^1,6 . 0 ^8,13] -3,8,10,12- tetradecanol tetra-ene, pentacyclo [6.5.1.1 ^3,6. 0 ^2,7 . 0 ^9,13] 4,10 penta octadecadienoic, pentacyclo [4.7.0.1 ^2,5. 0 ^8,13 . 1 ^9,12] -3-pentadecene, methyl-substituted pentacyclo [4.7.0.1 ^2,5. 0 ^8,13 . 1 ^9,12 ] -3-pentadecene, heptacyclo [7.8.0.1 ^3,6 . 0 ^2,7 . 1 ^10,17 . 0 ^11,16 . 1 ^12,15] -4-eicosene, dimethyl-substituted heptacyclo [7.8.0.1 ^3,6. 0 ^2,7 . 1 ^10,17 . 0 ^11,16 . 1 ^{12, 15]} -4-eicosene, Nonashikuro [9.10.1.1 ^4,7. 0 ^3,8 . 0 ^2,10 . 0 ^12,21 . 1 ^13,20 . 0 ^14,19 . 1 ^15,18] -5-pentacosene, trimethyl-substituted Nonashikuro [9.1.1.1 ^{4, 7.} 0 ^3,8 . 0 ^2,10 . 0 ^12,21 . 1 ^13,20 . 0 ^14,19 . 1 ^15,18] -5-pentacosene and the like.

In addition to the ethylene component and the cyclic olefin component represented by the above formula (1), the COC contains other copolymerizable unsaturated monomer components such as propylene, as long as the object of the present invention is not impaired. 1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene, etc. Α-olefin, norbornene, ethylidene norbornene, cyclic olefin such as dicyclopentadiene, cyclic diene and the like may be contained.

In the COC, the structural unit derived from ethylene is preferably in the range of 40 to 85 mol%, more preferably 50 to 75 mol%, and the structural unit derived from cyclic olefin is preferably 15 to 60 mol%. More preferably, it is in the range of 25 to 50 mol%. Since the structural unit derived from ethylene is contained within the above range, the film is excellent in rigidity, tearability, processing stability, and impact strength.

As a commercially available product that can be used as the cyclic olefin resin (a1), examples of the ring-opening polymer (COP) of the norbornene-based monomer include "ZEONOR" manufactured by Nippon Zeon Co., Ltd., and the norbornene-based polymer is used. Examples of the copolymer (COC) include "Apel" manufactured by Mitsui Kagaku Co., Ltd. and "TOPAS" manufactured by Polyplastics Co., Ltd.

<Ethylene resin (b1)>
The ethylene-based resin (b1) used for the layer (I) is an ethylene-based resin that satisfies the above conditions (i) and (ii).

≪Condition (i) ≫
The density of the ethylene-based resin (b1), the film rigidity, in view of heat sealability, 880~970kg / m ^3, preferably in the range of 885~950kg / m ^3, more preferably 900~930kg / m ^3. The density is a value measured according to JIS K7112 (density gradient tube method).

≪Condition (ii) ≫
MFR (190 ° C., 2.16 kg load, JIS K7210 compliant) of ethylene resin (b1) is 0.1 to 50 g / 10 minutes from the viewpoint of bubble stability, film strength, molding processability (fluidity), etc. It is preferably in the range of 0.5 to 30 g / 10 minutes, more preferably 0.7 to 15 g / 10 minutes.

Examples of the ethylene resin (b1) include linear low-density polyethylene. The linear low density polyethylene contains a copolymer of ethylene and α-olefin, and such a copolymer can be obtained by using a known catalyst such as a Ziegler-Natta catalyst or a metallocene catalyst. It is also possible to add other low density polyethylene. In the present invention, a polyethylene-based resin satisfying each of the above characteristics can be selected and used from commercially available polyethylene-based resins. Further, the ethylene resin (b1) may be used alone or in combination of two or more.

<Other ingredients>
The resin composition (I) may be a weather-resistant stabilizer, a heat-resistant stabilizer, an antistatic agent, an antifogging agent, an antiblocking agent, a slip agent, a lubricant, as long as it does not impair the object of the present invention. It may contain various additives usually added to polyolefins such as pigments and lubricants.

[Layer (II)]
The layer (II) in the multilayer film of the present invention is 10 to 70% by weight, preferably 20 to 65% by weight, more preferably 30 to 60% by weight of the cyclic olefin resin (a2), and the above conditions (i) and A resin composition containing 30 to 90% by weight, preferably 35 to 80% by weight, more preferably 40 to 70% by weight of the ethylene resin (b2) satisfying (ii) (provided that the component (a2) and the component (however, the component (a2)) and the component ( The total of b2) is 100% by weight. It is also referred to as "resin composition (II)" below).

The layer (II) is an intermediate layer of the multilayer film of the present invention. As described above, by including the cyclic olefin resin (a2) in the intermediate layer of the multilayer film in the above range, a multilayer film having excellent cutability can be obtained.

Examples of the cyclic olefin resin (a2) used for the layer (II) include the same as those exemplified for the cyclic olefin resin (a1). As the cyclic olefin resin (a2) used for the layer (II), the same type as the cyclic olefin resin (a1) may be used, or a different type may be used.

Further, as an example of the ethylene-based resin (b2) used for the layer (II), the same as those exemplified in the ethylene-based resin (b1) can be mentioned. As the ethylene resin (b2) used for the layer (II), the same type as that of the ethylene resin (b1) may be used, or a different type may be used. The ethylene resin (b2) may be used alone or in combination of two or more.

Further, the resin composition (II) may contain the other components in the same manner as the resin composition (I).

[Layer (III)]
The layer (III) in the multilayer film of the present invention contains an ethylene resin (b3) as a main component. The ethylene-based resin (b3) is not particularly limited as long as it is an ethylene-based resin used for a sealant, and examples thereof include the same as those exemplified in the ethylene-based resin (b1). As the ethylene resin (b3) used for the layer (III), the same type as the ethylene resin (b1) or (b2) may be used, or different types may be used.

The layer (III) is an inner layer (seal layer) of the multilayer film of the present invention. As described above, since the inner layer of the multilayer film is made of the ethylene resin (b3), a multilayer film having excellent heat sealing properties can be obtained. The layer (III) may be a single layer or a multi-layer including two or more layers. Further, the ethylene resin (b3) may be used alone or in combination of two or more.

The layer (III) may contain other components exemplified in the resin composition (I), if necessary, as long as the object of the present invention is not impaired.

[Layer (IV)]
The layer (IV) arbitrarily provided in the multilayer film of the present invention is the cyclic olefin resin (a3) 0 to 70% by weight, preferably 0 to 60% by weight, more preferably 1 to 55% by weight. A resin composition containing 30 to 100% by weight, preferably 40 to 100% by weight, more preferably 45 to 99% by weight of an ethylene resin (b4) satisfying (i) and (ii) (provided that the component (a3) is used. ) And the component (b4) are 100% by weight. Hereinafter, it is also referred to as “resin composition (IV)”).

By providing the layer (IV) between the layer (I) and the layer (II) and at least one between the layer (II) and the layer (III), the tear strength, the impact strength, It becomes possible to control physical properties such as rigidity.

Examples of the cyclic olefin resin (a3) used for the layer (IV) include the same as those exemplified for the cyclic olefin resin (a1). As the cyclic olefin resin (a3) used for the layer (IV), the same type as the cyclic olefin resin (a1) or (a2) may be used, or different types may be used.

Further, as an example of the ethylene-based resin (b4) used for the layer (IV), the same as those exemplified in the ethylene-based resin (b1) can be mentioned. As the ethylene resin (b4) used for the layer (IV), the same type as the ethylene resin (b1), (b2) or (b3) may be used, or a different type may be used. Good. Further, the ethylene resin (b4) may be used alone or in combination of two or more.

Further, the resin composition (II) may contain the other components in the same manner as the resin composition (I).

[Multilayer film]
The multilayer film of the present invention includes the above-mentioned layer (I), layer (II) and layer (III), and optionally includes the above-mentioned layer (IV).

In the multilayer film of the present invention, the total usage ratio of the cyclic olefin resins (a1), (a2) and (a3) to the entire film is preferably 0.1 to 60% by weight, more preferably 1 to 55% by weight. %, More preferably 5 to 50% by weight. When the total usage ratio of the cyclic olefin resins (a1), (a2) and (a3) in the entire multilayer film of the present invention is within the above range, stable film formation is possible and easy cutting property is achieved. Can be given.

The thickness of the multilayer film of the present invention may be appropriately set according to various uses, but the thickness of the layer (I) is usually in the range of 2 to 100 μm, preferably 4 to 80 μm, and the layer (I) The thickness of II) is usually in the range of 2 to 100 μm, preferably 4 to 80 μm, and the thickness of the layer (III) is usually in the range of 4 to 150 μm, preferably 8 to 120 μm. The thickness of the layer (IV) is usually in the range of 2 to 100 μm, preferably 4 to 80 μm.

The multilayer film of the present invention preferably has a haze of 50% or less, more preferably 30% or less, and even more preferably 20% or less as a 90 μm-thick multilayer film. When the haze is 50% or less, the transparency of the film is excellent.

The multilayer film of the present invention preferably has a dirt impact strength of 600 g or more, more preferably 700 g or more, as a 90 μm-thick multilayer film. When the dirt impact strength is 600 g or more, it has sufficient strength, and when applied as a food packaging bag, it is possible to prevent the bag from being torn during transportation or dropping. On the other hand, the upper limit is not particularly limited.

The multilayer film of the present invention preferably has an Elmendorf tear strength in the TD direction of 0.1 to 6N, more preferably 0.1 to 4N, and more preferably 0.1 to 3N as a 90 μm-thick multilayer film. Is even more preferable.

In the present specification, the "TD direction" (Transverse Direction) refers to a direction orthogonal to the MD direction and parallel to the main surface of the film, and the "MD direction" (Machine Direction) is the flow direction of the film. Point to.

The multilayer film of the present invention preferably has a tensile elastic modulus in the MD direction of 10 to 2500 MPa, more preferably 50 to 2000 MPa, and even more preferably 100 to 2000 MPa as a 90 μm-thick multilayer film. When the tensile elastic modulus in the MD direction is 10 MPa or more, the strength of the film is further improved. Further, when the tensile elastic modulus in the MD direction is 2500 MPa or less, the film has excellent mechanical strength such as tensile strength.

The multilayer film of the present invention preferably has a fine hardness of 250 to 1000 MPa, more preferably 300 to 900 MPa, and even more preferably 350 to 800 MPa as a 90 μm-thick multilayer film. When the minute hardness is within the above range, a multilayer film having appropriate rigidity is obtained. Further, the microhardness of the multilayer film of the present invention can be improved by 10% or more as compared with the microhardness of the multilayer film produced under the same conditions except that the cyclic olefin resin is not blended in the layer (I). preferable.

<Manufacturing method of multilayer film>
The method for producing the multilayer film of the present invention is not particularly limited, but for example, the resin composition used for each layer is coextruded and laminated in a molten state using a multilayer die, and then formed into a film by an inflation method or the like. A coextrusion method can be mentioned. The film thus obtained can be processed as a non-stretched film as it is, or further stretched as a stretched film into a film for producing a food packaging bag or the like. In that case, the thickness of the melt-extruded film (including a thick molded product called a stretched original fabric and a sheet depending on the thickness) differs depending on the molding method. The stretched raw fabric produced by inflation molding preferably has a thickness of 50 μm to 2000 μm, more preferably 100 μm to 1500 μm. The method for cooling the molten resin may be either air cooling or water cooling.

As a method of stretching the stretched raw fabric, a method of simultaneously or sequentially biaxially stretching in the vertical and horizontal directions by the tenter method, a method of simultaneously biaxially stretching in the vertical and horizontal methods by the tubular method, or a difference in the rotation speed ratio of two or more rolls. For example, a method of uniaxially stretching in the flow direction of the film can be exemplified.

<Use of multilayer film>
The multilayer film of the present invention includes water packaging bags, liquid soup packaging bags, liquid paper containers, lami raw fabrics, specially shaped liquid packaging bags (standing pouches, etc.), standard bags, heavy bags, wrap films, sugar bags, and oil packaging. It is suitable for bags, various packaging films for food packaging, protective films, infusion bags, agricultural materials, back-in boxes, semiconductor materials, pharmaceuticals, clean films used for packaging foods, and the like.

Hereinafter, the present invention will be described in more detail based on Examples, but the present invention is not limited to these Examples.

In the following examples, various physical properties were measured and evaluated as follows.

<Melt mass flow rate (MFR: [g / 10min])>
According to JIS K7210, the measurement was performed under the conditions of 190 ° C. and 2.16 kg load (kgf).

<Density [kg / m ³ ]>
According to JIS K7112, the strands obtained at the time of MFR measurement were heat-treated at 100 ° C. for 1 hour, left at room temperature for 1 hour, and then measured by the density gradient tube method.

<Haze>
According to JIS K7136, the measurement was performed with a digital turbidity meter "NDH-20D" manufactured by Nippon Denshoku Kogyo Co., Ltd. using a test piece (90 μm thickness).

<Elmendorf tear strength (TD direction)>
The measurement was performed under the following conditions in accordance with JIS K7128-2 (1998).
Measuring device: Tear tester (SA-WP, manufactured by Toyo Seiki Seisakusho Co., Ltd.)
Specimen size: width 75 mm x length 63 mm x thickness 90 μm (strip shape)
Measurement temperature: 23 ° C
<Dirt impact strength [g]>
Dirt impact strength was measured according to ASTM D1709 under the following conditions and methods.

The test piece (90 μm thickness) is tightened by an air clamp method, a hemispherical dirt is dropped from a certain height, and the load [g] at which the test piece breaks 50% is read from the graph. Method A is used with the number of drops per level being 10.

<Tensile modulus (MD direction)>
In accordance with JIS K6781, a test piece (90 μm thick) cut into a shape for a tensile cutting load was used. Tensile elastic modulus (MD method) (unit) of the test piece using a tensile tester (Instron's "Universal Tensile Tester 3380") under the conditions of a distance between chucks of 80 mm, a tensile speed of 500 mm / min, and a temperature of 23 ° C. : MPa) was measured.

<Micro hardness>
It was measured using a "dynamic ultrafine hardness tester DUH-W201S" manufactured by Shimadzu Corporation under the conditions of a temperature of 23 ° C. and a humidity of 50%, and was calculated by the hardness obtained from the indentation depth when a test load was applied.

<Curl>
As a test piece, a film was cut out in a size of 30 mm in length and 200 mm in width. As for the cutting direction, a sample cut by 200 mm along the MD direction was used as an MD sample, and a sample cut along the TD direction was used as a TD sample. The left end of the cut film sample was fixed with tape, the right end was pressed by hand so as to be in close contact with the table, and the lateral length was measured without touching the table when the hand was released. If the sample in each of the MD direction and the TD direction is less than 35 mm, it is evaluated as "pass", and if either of them is 35 mm or more, it is evaluated as "defective".

[Material used]
The various raw materials used in the examples and comparative examples are as follows.

<Ethylene / α-olefin copolymer>
LL1: "Evolu SP2510" manufactured by Prime Polymer Co., Ltd. (Density: 923 kg / m ³ , MFR: 1.4 g / 10 minutes)
LL2: "Evolu SP1022" manufactured by Prime Polymer Co., Ltd. (Density: 908 kg / m ³ , MFR: 2.0 g / 10 minutes)
LL3: "Evolu SP2520" manufactured by Prime Polymer Co., Ltd. (Density: 925 kg / m ³ , MFR: 1.9 g / 10 minutes)
LL4: "Evolu SP1520" manufactured by Prime Polymer Co., Ltd. (Density: 913 kg / m ³ , MFR: 2.0 g / 10 minutes)
<High density polyethylene>
HD: "HIZEX 3600F" manufactured by Prime Polymer Co., Ltd. (Density: 958 kg / m ³ , MFR: 1.0 g / 10 minutes)
<Polypropylene>
PP: "Prime Polypro F-300SP" manufactured by Prime Polymer Co., Ltd.
<Cyclic olefin resin>
COC1: "TOPAS 8007F-04" manufactured by Polyplastics Co., Ltd.
COC2: "Apel APL6509T" manufactured by Mitsui Chemicals, Inc.
[Examples 1 to 3 and Comparative Examples 1 to 5]
An inflation film having the layer structure shown in Table 1 (thickness 90 μm, layer ratio 1: 1: 1) was produced under the following conditions.

<Film molding conditions>
Molding machine: Alpine 3-layer inflation film molding machine Extruder Screw diameter: 50 mmφ x 3 units Die diameter: 225 mmφ
Die lip gap: 3.0mm
Extrusion amount: 111 kg / h (37 kg / h each)
Pick-up speed: 15m / min. Expansion ratio: 2.0
Molding temperature: 190 ° C
Cooling ring: Triple type The above physical properties were measured and evaluated using the obtained film. The results are shown in Table 1.

上記表１に示すように、実施例１および２と比較例２とを対比すると、層（Ｉ）に環状オレフィン系樹脂を配合することにより、透明性、易カット性、衝撃強度および引張弾性率を維持しつつ、カールを発生させずに表面硬度（微小硬度）が向上したことが判明した。特に実施例２の表面硬度は比較例２よりも１０％以上向上していることが判明した。同様に実施例３と比較例３とを対比すると、実施例３では表面硬度が１０％以上向上し、かつ他の特性は維持されていることが判明した。

As shown in Table 1 above, comparing Examples 1 and 2 with Comparative Example 2, by blending the cyclic olefin resin in the layer (I), transparency, easy-to-cut property, impact strength and tensile modulus. It was found that the surface hardness (micro-hardness) was improved without causing curl while maintaining the above. In particular, it was found that the surface hardness of Example 2 was improved by 10% or more as compared with Comparative Example 2. Similarly, when Example 3 and Comparative Example 3 were compared, it was found that the surface hardness of Example 3 was improved by 10% or more and other characteristics were maintained.

Claims (4)

A resin composition containing 0.1 to 10% by weight of the cyclic olefin resin (a1) and 90 to 99.9% by weight of the ethylene resin (b1) satisfying the following conditions (i) and (ii). The total of the component (a1) and the component (b1) is 100% by weight), and the layer (I).
A resin composition containing 10 to 70% by weight of the cyclic olefin resin (a2) and 30 to 90% by weight of the ethylene resin (b2) satisfying the following conditions (i) and (ii) (however, the component (a2)). And the component (b2) are 100% by weight.) And the layer (II).
Multilayer film containing a layer (III) containing an ethylene resin (b3):
(I) The density is 880-970 kg / m ³ ;
(Ii) The melt mass flow rate (MFR) at 190 ° C. and a load of 2.16 kg is 0.1 to 50 g / 10 minutes. The multilayer film according to claim 1, wherein the cyclic olefin resins (a1) and (a2) are ethylene / cyclic olefin copolymers. Cyclic olefin resin (a3) 0 to 70% by weight, and the above conditions, between the layer (I) and the layer (II) and at least one between the layer (II) and the layer (III). From a resin composition containing 30 to 100% by weight of an ethylene resin (b4) satisfying (i) and (ii) (however, the total of the component (a3) and the component (b4) is 100% by weight). The multilayer film according to claim 1 or 2, further comprising a layer (IV). The multilayer film according to claim 3, wherein the total usage ratio of the cyclic olefin resins (a1), (a2) and (a3) to the entire film is 0.1 to 60% by weight.