JP2007216455A - Polyolefinic multilayered film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyolefinic multilayered film superior in transparency, rubbery elasticity and flexibility. <P>SOLUTION: The polyolefinic multilayered film is composed of at least one surface layer (X) and at least one core layer (Y), and the surface layer (X) comprises an ethylene/α-olefin copolymer with a density of 0.850-0.940 g/cm<SP>3</SP>and a 3-20C α-olefin content of 5-50 mol% while the core layer (Y) is composed of 0-70 wt.% of a polypropylene resin (A) with a melting point of 120-170°C and 30-100 wt.% of a propylene/α-olefin copolymer (B) of which the melting point is 120°C or below or not observed and the α-olefin content is 5-50 mol%. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a polyolefin-based multilayer film. In particular, the present invention relates to a polyolefin-based multilayer film having high transparency and excellent flexibility, stretchability, rubber elasticity and stretchability. The polyolefin multilayer film of the present invention can be suitably used as a food, a fiber wrapping film or label, a film for a patch, and a protective film.

 Polyvinyl chloride and polyvinylidene chloride are widely used for flexible films used for foods, textile packaging, labels, films for adhesives, protective films for building materials and electronic / electronic devices, and the like. However, since these films contain a large amount of chlorine atoms in the raw material resin, there is a possibility that dioxins may be generated depending on the disposal and incineration methods, and flexible films that do not contain chlorine atoms have been developed. It has been broken.

Conventionally, as a polyolefin-based soft film containing no chlorine atom, a single layer or a multilayer in which a film made of a composition comprising low density polyethylene or ethylene / vinyl acetate copolymer (EVA) and various resins is at least one layer. A single-layer or multi-layer film is known in which at least one layer is a film or a film made of a composition comprising soft polypropylene and various resins. Such a film is excellent in flexibility, but is inferior in stretchability, rubber elasticity and transparency, and has limited uses.
Japanese Patent Application Laid-Open No. 2003-192580 (Patent Document 1) proposes a film for sticking using a thermoplastic elastomer as a base layer and an ethylene / α-olefin copolymer obtained by a metallocene catalyst as a surface layer. . The film according to the publication is inferior in stretchability and rubber elasticity, and further improvement is desired.
JP 2003-192580 A

 An object of the present invention is to provide a polyolefin-based multilayer film excellent in transparency, flexibility, stretchability, and rubber elasticity.

  The present inventors have found that the above problems can be solved by a multilayer film using a composition comprising a polypropylene resin and a specific propylene / α-olefin copolymer as a surface layer, and have completed the present invention. .

That is, according to the present invention, in a multilayer film composed of at least one surface layer (X) and a core layer (Y), the surface layer (X) has a density of 0.850 to 0.940 g / cm ³ and a carbon number of 3 to 20. The α-olefin content of the ethylene / α-olefin copolymer is in the range of 5 to 50 mol%, and the core layer (Y) has a melting point of 120 ° C. to 170 ° C. and the polypropylene resin (A) is 0 to 70% by weight. And a melting point of less than 120 ° C. or a melting point is not observed, and a propylene / α-olefin copolymer (B) having an α-olefin content of 5 to 50 mol% is formed from a resin composition consisting of 30 to 100% by weight. A polyolefin-based multilayer film.

  The multilayer film of the present invention is excellent in transparency, flexibility, stretchability, and rubber elasticity, and can be suitably used as a protective film for foods, fiber packaging, labels, building materials, and electronic / electronic devices.

  The multilayer film of the present invention is formed from at least one surface layer (X) and a core layer (Y).

In the film of the present invention, the surface layer (X) has a density of 0.850 to 0.940 g / cm ³ , and an ethylene / α- having a C 3-20 α-olefin content of 5 to 50 mol%. It is formed from an olefin copolymer.

  The ethylene / α-olefin random copolymer is a random copolymer obtained by copolymerizing ethylene and an α-olefin having 3 to 20 carbon atoms, preferably 3 to 10 carbon atoms. Specific examples of the α-olefin include propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene and 1-dodecene, preferably 1- Butene, 1-hexene, 1-octene, more preferably 1-butene. The α-olefin content in the copolymer is 5 to 50 mol%, preferably 7 to 30 mol%, based on 100 mol% of the total of ethylene and the α-olefin having 3 to 20 carbon atoms.

The MFR (ASTM D1238, 190 ° C., 2.16 kg load) of the ethylene / α-olefin random copolymer is 0.1 to 50, preferably 0.2 to 30 (g / 10 min), and the density (ASTM D1505). ) Is 0.850 to 0.940 (g / cm ³ ), preferably 0.855 to 0.920 (g / cm ³ ), more preferably 0.860 to 0.910 (g / cm ³ ). . If it is this range, it will be excellent in especially the elasticity of a laminated film, and rubber elasticity. The melting point determined by differential scanning calorimetry (DSC) of the ethylene / α-olefin random copolymer is preferably less than 120 ° C. or no melting point is observed, and more preferably the melting point is in the range of 50 to 110 ° C. The DSC measurement was held at 200 ° C. for 5 minutes, then the temperature was decreased to −20 ° C. at a temperature decrease rate of −20 ° C./min, and then the endotherm observed when the temperature was increased again to 180 ° C. at 20 ° C./min. Measure the peak. “A melting point is not observed” means that a peak having a heat of crystal melting of 1 J / g or more is not observed.

The method for producing the ethylene / α-olefin random copolymer is not particularly limited, but can be produced by copolymerizing ethylene and α-olefin in the presence of a Ziegler-Natta catalyst or a metallocene catalyst. . Preferred is an ethylene / α-olefin random copolymer obtained by copolymerizing ethylene and an α-olefin in the presence of a metallocene catalyst.
Furthermore, in this invention, it can also be used by the composition which blended several types of ethylene * alpha-olefin random polymers from which density and / or MFR differ.

  The molecular structure of the ethylene / α-olefin random copolymer used in the present invention may be linear or branched having long or short side chains.

The core layer (Y) of the multilayer film in the present invention is formed from a resin composition comprising a polypropylene resin (A) and a propylene / α-olefin copolymer (B).
Hereinafter, each component will be described.

Polypropylene resin (A)
The polypropylene resin (A) used in the present invention is a known propylene homopolymer having a melting point measured by a differential scanning calorimeter (DSC) in the range of 120 to 170 ° C., or ethylene or α having 4 to 20 carbon atoms. Mention may be made of random or block copolymers with olefins. From the viewpoint of transparency and flexibility, a random copolymer is preferably used. More preferably, a random copolymer having an MFR measured at 230 ° C. (hereinafter abbreviated as MFR ₂₃₀ ) in the range of 0.5 to 100 g / 10 min and a melting point in the range of 120 to 155 ° C., more preferably MFR ₂₃₀ is 1 A random copolymer having a melting point of 125 to 150 ° C. is used in the range of ˜20 g / 10 min. The DSC measurement was held at 200 ° C. for 5 minutes, then the temperature was decreased to −20 ° C. at a temperature decrease rate of −20 ° C./min, and then the endotherm observed when the temperature was increased again to 180 ° C. at 20 ° C./min. Measure the peak.
The propylene content of the propylene polymer (A) is 80 to 100 mol%, preferably 85 to 100 mol%, more preferably 90 to 99 mol%.

 Such a polypropylene resin (A) typically polymerizes propylene in the presence of a solid titanium catalyst and a catalyst mainly composed of an organometallic compound, or a metallocene catalyst using a metallocene compound as one component of the catalyst. It can be produced by copolymerizing propylene and other α-olefins.

Propylene / α-olefin copolymer (B)
The propylene / α-olefin copolymer (B) used in the film of the present invention is a random copolymer of propylene and ethylene or an α-olefin having 4 to 20 carbon atoms, and is measured by a DSC method. Melting point (endothermic peak when observed when holding at 200 ° C. for 5 minutes, then decreasing to −20 ° C. at a temperature decrease rate of −20 ° C./min and then increasing again to 180 ° C. at 20 ° C./min) Below 120 ° C or not observed. “A melting point is not observed” means that a peak having a heat of crystal melting of 1 J / g or more is not observed.
Preferably, it is a copolymer of propylene / ethylene / α-olefin having 4 to 20 carbon atoms, and no melting point is observed.

The MFR ₂₃₀ of the propylene / α-olefin copolymer (B) is in the range of 0.1 to 70 g / 10 min, preferably 0.3 to 50 g / 10 min, more preferably 1.0 to 20 g / 10 min. The α-olefin content other than propylene is 5 to 50 mol%, preferably 10 to 40 mol%. Here, the total of propylene and α-olefin is 100 mol%. As the α-olefin component, ethylene and an α-olefin having 4 to 10 carbon atoms, preferably ethylene, 1-butene, 1-hexene, 4-methyl-1-pentene, 1-octene, more preferably ethylene, 1-butene can be mentioned.

  Such a propylene / α-olefin copolymer (B) is typically a catalyst mainly composed of a solid titanium catalyst and an organometallic compound, or a metallocene catalyst using a metallocene compound as one component of the catalyst. It can be produced by copolymerizing propylene and α-olefin under pressure.

  As the most preferred form of the propylene / α-olefin copolymer (B), the following propylene / ethylene / α-olefin random copolymer (B-1) having 4 to 20 carbon atoms can be exemplified.

Propylene / ethylene / C4-C20 α-olefin random copolymer (B-1)
The propylene / ethylene / C4-C20 α-olefin random copolymer (B-2) preferably used in the present invention satisfies the following (m) and (n);
(M) The molecular weight distribution measured by gel permeation chromatography (GPC) is 1.0 to 3.0 (n) 40 to 85 mol% of propylene-derived structural units and 5 to 30 mol of ethylene-derived structural units. %, 5 to 30 mol% of a structural unit derived from an α-olefin having 4 to 20 carbon atoms. In addition, the sum total of the structural unit derived from ethylene and the structural unit derived from a C4-C20 olefin is 50-5 mol% here.

In the present invention, it is further preferable to satisfy at least one of the following (o) and (p), preferably both:
(O) Shore A hardness of 30-80, preferably 35-60
(P) The crystallinity measured by X-ray diffraction is 20% or less, preferably 10% or less.

  In more detail about the amount of propylene component and other comonomer components, the propylene-derived structural unit is preferably 60 to 82 mol%, more preferably 61 to 75 mol%, and the ethylene-derived structural unit is preferably 8 to 15 mol%, More preferably, the constituent unit derived from α-olefin having 10 to 14 mol% and 4 to 20 carbon atoms is contained in an amount of preferably 10 to 25 mol%, more preferably 15 to 25 mol%. With regard to the α-olefin having 4 to 20 carbon atoms, 1-butene is particularly preferable.

  Such a propylene / ethylene / α-olefin random copolymer (B-1) can be obtained, for example, by the method described in International Publication No. 2004/87775.

  In the present invention, (B-1) propylene / ethylene / α-olefin random copolymer having 4 to 20 carbon atoms is used, so that flexibility, rubber elasticity, transparency are improved, and impact resistance is also improved. Excellent film.

Resin Composition The core (Y) of the multilayer film of the present invention comprises 0 to 70% by weight of the polypropylene resin (A) and 30 to 100% by weight of the propylene / α-olefin copolymer (B). Preferably, the polypropylene resin (A) is 5 to 50% by weight, and the propylene / α-olefin copolymer (B) is 50 to 95% by weight, more preferably, the polypropylene resin (A) is 7 to 40% by weight, and propylene / α. -It consists of 60 to 93 weight% of olefin copolymers (B).
In addition, as long as the effect of this invention is not impaired in this resin composition, you may contain other polyolefin resin, such as a polyethylene resin. Moreover, you may contain arbitrary components, such as a tackifier and surfactant which are mentioned later, unless the effect of this invention is impaired.

Multilayer film The multilayer film of the present invention has at least two layers formed of at least one surface layer and at least one core layer (Y). Specifically, for example, surface layer (X) / core layer (Y), surface layer (X) / core layer (Y) / surface layer (X), surface layer (X) / core layer (Y) / core Layer (Y ′) / surface layer (X). Here, when a plurality of surface layers (X) and / or core layers (Y) are formed, they may have the same composition or different compositions.

  The total thickness of the multilayer film of the present invention is 3 to 500 μm, preferably 5 to 400 μm, from the viewpoints of film strength, flexibility, and transparency. The thickness of the surface layer (X) of the multilayer film of the present invention is 0.5 to 200 μm, preferably 1 to 150 μm, and the thickness of the core layer (Y) is 1 to 300 μm, preferably 2 to 200 μm.

  The film production method of the present invention can be produced using a multilayer T-die molding machine or an inflation molding machine used for ordinary polyolefin film molding.

 A tackifier and a surfactant may be added to the film of the present invention in order to adjust the tackiness and antifogging property. Examples of the tackifier include liquid hydrocarbons such as polybutene and olefin oligomers, liquid paraffin, fatty petroleum resins, alicyclic petroleum resins, and the like. Examples of the surfactant include monoglycerin fatty acid ester, glycerin fatty acid ester, and sorbitan fatty acid ester. These may be used alone or as a mixture of two or more.

  The multilayer film of the present invention may be stretched in at least one direction as long as the characteristics of the present invention are not impaired, and may be a stretched film.

  The multilayer film of the present invention is excellent in transparency, stretchability, rubber elasticity and flexibility, and is used as a packaging film for foods and fibers, a film for labels, a film for adhesive materials, and a protective film for building materials, electrical and electronic equipment. Available. In particular, because it is excellent in shape followability, printability, shape stability after application, etc., it can be used for label films, adhesive film, building materials / electrical / electronic devices, protective films for parts, water-stopping, etc. Suitable as a shielding film.

For example, as the label film, the multilayer film can be used without limitation, and a multilayer film having a printed layer and a multilayer film having a layer colored by adding a pigment can be used if necessary. It is not something.
The label film can be used by bonding to a base material selected from, for example, glass, metal (iron plate, aluminum plate, etc.), thermoplastic resin, wood and the like. In particular, it is preferable to bond with glass, metal, or wood. The obtained article is a laminate of a base material such as glass, metal (metal, aluminum plate, etc.) and wood and the multilayer film of the present invention.
The protective film protects building materials, electricity, electronic devices and parts by covering the surfaces of building materials, electricity, electronic devices and parts, for example.
In addition, an adhesive layer or a drug agent layer can be provided and used as a film for an adhesive material such as an anti-inflammatory analgesic or a skin disease tape, or a sanitary material tape such as a diaper or a sanitary product.

  EXAMPLES Next, although an Example demonstrates this invention, this invention is not limited to this.

[Evaluation method]
MFR ₂₃₀ : Measured at 230 ° C. under a load of 2.16 kg in accordance with ASTM D1238.
MFR ₁₉₀ : Measured at 190 ° C. under a load of 2.16 kg in accordance with ASTM D1238.
Density: Measured according to ASTM D1505.
Haze: Measured according to ASTM D1003.
Melting point: Measured using a differential scanning calorimeter (DSC) at a temperature elevation rate of 20 ° C./min.
Residual strain: Strain when a specimen of 50 mm in length and 10 mm in width is strained to 150% (75 mm between chucks) at a tensile speed of 20 mm / min using a tensile tester with 30 mm between chucks, and then immediately unloaded. The length (T1) (mm) was measured, and the residual strain (%) was set to T1 / 30 × 100.

  Mw / Mn: The measurement conditions of GPC are values determined in terms of polystyrene in 140 ° C. and orthodichlorobenzene. For example, GPC-150C manufactured by Waters can be used as an apparatus, and the separation column can be measured using TSKgel GNH6-HT and TSKgel GNH6-HTL.

[Example 1]
Using the following resins as the core layer and the surface layer, the layer structure (surface layer 25 μm) / (core layer 100 μm) / in a three-layer three-layer inflation molding machine with a diameter of 100 mmφ equipped with a 50 mmφ extruder / A three-layer film consisting of (surface layer 25 μm) was obtained. The physical properties of the obtained film are shown in Table-1.
Surface layer resin: MFR ₁₉₀ 1.2 g / 10 min, melting point 75 ° C., butene content 19 mol%, Mw / Mn = 2.0 ethylene / 1-butene random copolymer (manufactured with metallocene catalyst)
Core layer resin: Propylene / ethylene / 1-butene random copolymer having a MFR _{230 of} 7.0 g / 10 min, a melting point of 138 ° C., an ethylene content of 2 mol%, and a 1-butene content of 2 mol% (titanium catalyst) Production) 20% by weight, and propylene / α-olefin copolymer, MFR ₂₃₀ 7.0 g / 10 min, ethylene content 13 mol%, butene content 19 mol%, Mw / Mn = 2.1, no melting point observed A composition comprising 80% by weight of a propylene / ethylene / 1-butene copolymer (manufactured with a metallocene catalyst).

[Comparative Examples 1 and 2]
A film was obtained in the same manner as in Example 1 except that the resin composition described in Table 1 was used as the surface layer resin. The physical properties of the obtained film are shown in Table-1.

[Example 2]
A film was obtained in the same manner as in Example 1 except that the core layer resin composition was changed to the composition shown in Table-1. The physical properties of the obtained film are shown in Table-1.

LLDPE-1；エチレン・α−オレフィン共重合体
（エチレン・１−ブテン共重合体）
密度0.885g/cm³、MFR₁₉₀ 1.2g/10min、1-ブテン含量19モル%
Mw/Mn=2.0、メタロセン触媒で製造
HPLDPE-1；高圧法低密度ポリエチレン
密度0.917g/cm³、MFR₁₉₀ 2.0g/10min
PP-1； ポリプロピレン樹脂
MFR₂₃₀ 7.0g/10min, 融点 138℃
PBER-1；プロピレン・α−オレフィン共重合体
（プロピレン・エチレン・１−ブテン共重合体）
MFR₂₃₀ 7.0g/10min, 融点 観測されず、エチレン含量13モル％、
1-ブテン含量 19モル%、分子量分布 2.1、メタロセン触媒で製造

LLDPE-1; Ethylene / α-olefin copolymer
(Ethylene / 1-butene copolymer)
Density 0.885g / cm ³ , MFR ₁₉₀ 1.2g / 10min, 1-butene content 19mol%
Mw / Mn = 2.0, manufactured with metallocene catalyst
HPLDPE-1: High-pressure low-density polyethylene
Density 0.917g / cm ³ , MFR ₁₉₀ 2.0g / 10min
PP-1; Polypropylene resin
MFR ₂₃₀ 7.0g / 10min, melting point 138 ℃
PBER-1: Propylene / α-olefin copolymer
(Propylene / ethylene / 1-butene copolymer)
MFR ₂₃₀ 7.0g / 10min, melting point not observed, ethylene content 13 mol%,
1-butene content 19 mol%, molecular weight distribution 2.1, produced with metallocene catalyst

The multilayer film of the present invention is excellent in transparency, rubber elasticity, flexibility, and is suitable as a packaging film for foods and fibers, a film for labels, a film for adhesive materials, a protective film for building materials, electrical and electronic equipment, Its industrial utility value is extremely high.

Claims (2)

In a multilayer film composed of at least one surface layer (X) and a core layer (Y), the surface layer (X) contains an α-olefin having a density of 0.850 to 0.940 g / cm ³ and a carbon number of 3 to 20. It consists of an ethylene / α-olefin copolymer in an amount in the range of 5 to 50 mol%, and the core layer (Y) is a polypropylene resin (A) having a melting point of 120 ° C. to 170 ° C. However, the content of the propylene / α-olefin copolymer (B) is 30 to 100% by weight with a melting point of less than 120 ° C. or no melting point measured by DSC. A polyolefin-based multilayer film formed from a resin composition comprising: The propylene / α-olefin copolymer (B) is a propylene / ethylene / α-olefin random copolymer (B-1) having 4 to 20 carbon atoms satisfying the following (m) and (n): The polyolefin multilayer film according to claim 1,
(M) The molecular weight distribution measured by gel permeation chromatography (GPC) is 1.0 to 3.0. (N) 40 to 85 mol% of propylene-derived structural units and 5 ethylene-derived structural units. -30 mol% and 5-30 mol% of structural units derived from a C4-C20 alpha olefin.