JP6942530B2 - Multi-layer biaxially stretched film and transfer film - Google Patents

Description

The present invention relates to a multilayer biaxially stretched film having excellent releasability. In particular, the present invention relates to a multilayer biaxially stretched film which is excellent in releasability by containing a 4-methyl-1-pentene polymer in the release layer and is less likely to generate delamination during biaxial stretching. More specifically, the present invention relates to a multilayer biaxially stretched film useful for a release film, a release liner, a separator film, a transfer film and the like.

It is common to attach a surface protective film to the surface of resin products, metal products, glass products, etc. for building materials and optics to prevent surface scratches and foreign matter from being mixed during transportation, storage, or processing. In addition to properties such as flexibility and mechanical properties, the surface protective film is required to have various properties depending on the object to be protected, the purpose of protection, the environment in which it is used, and the like. Therefore, the development of surface protection films is being promoted from various viewpoints. For example, a surface protective film mainly composed of a polyethylene component (Patent Document 1) and a surface protective film of a resin composition containing an oligomer of 4-methyl-1-pentene and 1-decene mainly composed of a polypropylene component have been studied. (Patent Document 2).

Biaxially stretched polypropylene film is widely used as a material film for packaging and industrial use because it is excellent in light weight, thermal stability and mechanical properties. Particularly in recent years, it has been widely used as a non-silicone release material as a film for manufacturing process of electronic parts, electronic substrates, and thermosetting materials such as fiber reinforced plastics, but further improvement has been requested. .. As a method for improving the releasability, for example, it has been proposed that the peeling force can be further enhanced by blending a polymethylpentene polymer with polypropylene (Patent Documents 3 and 4). However, it is known that increasing the content of polymethylpentene deteriorates the biaxial stretchability, and in the case of a multilayer film, delamination (delamination) occurs, and further, α-olefin copolymers are compatible. Improvements such as compounding as a chemical material have been proposed (Patent Document 5).

The present inventors have already disclosed a release film containing a poly4-methyl-1-pentene copolymer characterized by excellent mold releasability and a relatively low moldable temperature. It has been confirmed that when the moldable temperature is lowered, there is no problem in practical use, but the transparency of the film tends to deteriorate (Patent Document 6).
As described above, in recent years, there has been a demand for the development of a film having excellent processability such as biaxial stretching, excellent appearance, and good releasability.

Japanese Unexamined Patent Publication No. 2006-116769 Japanese Unexamined Patent Publication No. 2010-275340 Japanese Unexamined Patent Publication No. 2008-189795 Japanese Unexamined Patent Publication No. 7-070384 JP-A-2015-120331 Japanese Unexamined Patent Publication No. 2014-125496

In order to improve the gloss of the obtained transfer product when the above-mentioned known multilayer film containing a 4-methyl-1-pentene polymer is used as the transfer film, the present inventors have performed the release layer. I wondered if it would be possible to improve the surface smoothness of the film. Then, we aimed to develop a multi-layer biaxially stretched film having better surface smoothness while maintaining the excellent releasability and heat resistance of the conventional film. That is, an object of the present invention is to provide a film which is difficult to delaminate (delamination), has particularly excellent surface smoothness, and has excellent mold releasability and heat resistance.

As a result of diligent studies to solve the above problems, the present inventors have made a layer formed from a composition containing a specific 4-methyl-1-pentene polymer and 4-methyl-1-pentene copolymer. It has been found that the multilayer biaxially stretched film having the above-mentioned problem can be solved, and the present invention has been completed.

That is, the present invention relates to the following [1] to [6].
[1] A multi-layer biaxially stretched film in which layers A and B are laminated.
The A layer is composed of a resin composition containing a 4-methyl-1-pentene polymer (A1) and a 4-methyl-1-pentene copolymer (A2).
The content of the 4-methyl-1-pentene polymer (A1) in the A layer is 5% by mass or more and 50% by mass or less with respect to the total mass of the A layer, and both 4-methyl-1-pentene are used. The content of the polymer (A2) is 50% by mass or more and 95% by mass or less with respect to the total mass of the A layer.
Moreover, the 4-methyl-1-pentene polymer (A1) satisfies the following requirements (A1-I) to (A1-II), and the 4-methyl-1-pentene copolymer (A2) meets the following requirements (A2). A2-I) meets - the (A2-II),
The B layer is formed from a resin composition containing polypropylene (B1).
Multi-layer biaxially stretched film.
It contains 90 mol% to 100 mol% of a structural unit derived from (A1-I) 4-methyl-1-pentene.
The melting point (Tm) measured by (A1-II) DSC is in the range of 200 ° C. to 250 ° C.
The content of the structural unit (P) derived from (A2-I) 4-methyl-1-pentene is 65 mol% or more and less than 96 mol%, and the α-olefin (4-methyl-) having 2 to 20 carbon atoms. The content of the structural unit (BQ) derived from 1-pentene) is more than 4 mol% and 35 mol% or less.
(A2-II) The melting point (Tm) measured by DSC is not observed or is in the range of 100 ° C to 199 ° C.
[2] The multilayer biaxially stretched film according to [1], wherein the 4-methyl-1-pentene polymer (A1) further satisfies the following requirement (A1-III).
(A1-III) The ultimate viscosity [η] measured in 135 ° C. decalin is 0.5 to 5.0 dl / g.
[3] The 4-methyl-1-pentene copolymer polymer (A2) further satisfies the following requirement (A2-III), the multilayer biaxially oriented film according to [1] or [2].
(A2-III) The ultimate viscosity [η] measured in 135 ° C. decalin is 0.5 to 4.0 dl / g.
[ 4 ] The layer structure is a three-layer structure of A layer / B layer / A layer or A layer / B layer / C layer (here, C layer is a layer different from both A layer and B layer). The multilayer biaxially stretched film according to any one of [1] to [ 3].
[ 5 ] The multilayer biaxially stretched film according to any one of [1] to [4 ], wherein the multilayer biaxially stretched film is a transfer film.

According to the present invention, there is provided a multilayer biaxially stretched film which is less likely to generate delamination during biaxial stretching, has particularly excellent surface smoothness, and is excellent in releasability and heat resistance.

Hereinafter, specific embodiments of the present invention will be described in detail, but the present invention is not limited to the following embodiments, and the present invention is carried out with appropriate modifications within the scope of the object of the present invention. be able to. In the present specification, the numerical range represented by using "~" means a range including the numerical values before and after "~" as the lower limit value and the upper limit value.

In addition, when referring to the amount of each component in the composition in the present specification, when a plurality of substances corresponding to each component are present in the composition, unless otherwise specified, a plurality of substances present in the composition. Means the total amount of substances in.

In the multilayer biaxially stretched film of the present invention, the A layer and the B layer are laminated, and the A layer is referred to as a 4-methyl-1-pentene polymer (A1) (hereinafter, also simply referred to as a polymer (A1)). It is composed of a resin composition containing a 4-methyl-1-pentene copolymer (A2) (hereinafter, also simply referred to as a copolymer (A2)).
Hereinafter, the A layer and the B layer will be described in detail, and then the layer structure and the film manufacturing method will be described.

≪A layer≫
The A layer contains a 4-methyl-1-pentene polymer (A1) and a 4-methyl-1-pentene copolymer (A2). The content of the 4-methyl-1-pentene polymer (A1) in the A layer is 5% by mass or more and 50% by mass or less with respect to the total mass of the A layer, and the 4-methyl-1-pentene co-weight is used. The content of the coalescence (A2) is 50% by mass or more and 95% by mass or less with respect to the total mass of the A layer. Preferably, the content of the 4-methyl-1-pentene polymer (A1) is 10% by mass or more and 40% by mass or less with respect to the total mass of the A layer, and the 4-methyl-1-pentene co-weight is preferable. The content of the coalescence (A2) is 60% by mass or more and 90% by mass or less with respect to the total mass of the A layer. Within the above range, the 4-methyl-1-pentene polymer (A1) can be finely dispersed in the A layer. Further, when the content of the 4-methyl-1-pentene polymer (A1) is at least the above lower limit value, the heat resistance of the A layer is excellent. When the content of the 4-methyl-1-pentene copolymer (A2) is at least the above lower limit value, the interlayer strength is excellent and it becomes difficult to delaminate.

Further, as will be described later, the polymer (A1) and the copolymer (A2) both contain a specific amount or more of a structural unit derived from 4-methyl-1-pentene to form a polymer (A1). It is considered that the compatibility with the copolymer (A2) is excellent and the gloss of the obtained film is excellent.

[4-Methyl-1-pentene polymer (A1)]
Hereinafter, the 4-methyl-1-pentene polymer (A1), which is a component constituting the A layer, will be described. The 4-methyl-1-pentene polymer (A1) satisfies the following requirements (A1-I) to (A1-II).

<Requirements (A1-I)>
The 4-methyl-1-pentene polymer (A1) contains 90 mol% to 100 mol% of the structural units derived from 4-methyl-1-pentene. Preferably, it contains a structural unit (AQ) derived from an olefin having 2 to 20 carbon atoms (excluding 4-methyl-1-pentene) in a proportion of 0 mol% to 10 mol%. The olefin having 2 to 20 carbon atoms is not limited to one type, and two or more types may be combined.

Here, from the viewpoint of heat resistance, it is preferable that the constituent unit derived from 4-methyl-1-pentene is contained in an amount of 93 mol% or more.
On the other hand, the structural unit (AQ) derived from an olefin having 2 to 20 carbon atoms (excluding 4-methyl-1-pentene) is contained in an amount of 10 mol% or less, preferably 7 mol% or less.

Examples of the olefin having 2 to 20 carbon atoms that can be contained in the 4-methyl-1-pentene polymer (A1) include ethylene, propylene, 1-butene, 1-pentene, 1-hexene, and 3-methyl-1-. Suitable examples include butene, 3-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-eicosene and the like. These olefins having 2 to 20 carbon atoms can be used alone or in combination of two or more. From the viewpoint of imparting appropriate elastic modulus, flexibility, and flexibility, olefins having 8 to 18 carbon atoms (for example, 1-octene, 1-decene, 1-tetradecene, 1-hexadecene, 1-heptadecene and 1-) Octadesene) is preferred.

The 4-methyl-1-pentene polymer (A1) contains 4-methyl-1-pentene and an olefin having 2 to 20 carbon atoms (4-methyl-1-) as long as the object of the present invention is not impaired. It may contain a structural unit derived from a polymerizable compound (hereinafter, also referred to as a polymerizable compound) other than (excluding penten).

Examples of such polymerizable compounds include vinyl compounds having a cyclic structure such as styrene, vinylcyclopentene, vinylcyclohexane, and vinylnorbornene; vinyl esters such as vinyl acetate; unsaturated organic acids such as maleic anhydride, or derivatives thereof. Conjugate dienes such as butadiene, isoprene, pentadiene, 2,3-dimethylbutadiene; 1,4-hexadiene, 1,6-octadien, 2-methyl-1,5-hexadiene, 6-methyl-1,5-heptadiene , 7-Methyl-1,6-octadien, dicyclopentadiene, cyclohexadiene, dicyclooctadien, methylenenorbornene, 5-vinylnorbornene, 5-ethylidene-2-norbornene, 5-methylene-2-norbornene, 5-isopropi LIDEN-2-norbornene, 6-chloromethyl-5-isopropenl-2-norbornene, 2,3-diisopropylidene-5-norbornene, 2-ethylidene-3-isopropylidene-5-norbornene, 2-propenyl-2, Examples thereof include non-conjugated polyenes such as 2-norbornene.

In the 4-methyl-1-pentene polymer (A1) in the present invention, the unit derived from the polymerizable compound is the structure of all the polymerizable compounds contained in the 4-methyl-1-pentene polymer (A1). It may be contained in an amount of 10 mol% or less, 5 mol% or less, and 3 mol% or less with respect to the unit.

<Requirements (A1-II)>
The 4-methyl-1-pentene polymer (A1) in the present invention has a melting point (Tm) measured by DSC in the range of 200 to 250 ° C. It is preferably in the range of 200 ° C. to 245 ° C., more preferably 200 ° C. to 240 ° C. The above-mentioned melting point (Tm) value is a value that changes depending on the stereoregularity of the polymer and the amount of α-olefin that polymerizes together, and is controlled and adjusted to a desired composition by using a catalyst for olefin polymerization described later. It is possible.

A polymer composition containing a 4-methyl-1-pentene polymer (A1) having a melting point (Tm) in the above range is preferable from the viewpoint of heat resistance.
The 4-methyl-1-pentene polymer (A1) preferably satisfies the following requirements (A1-III) in addition to the above requirements (A1-I) to (AI-II).

<Requirements (A1-III)>
The intrinsic viscosity [η] of the 4-methyl-1-pentene polymer (A1) measured in 135 ° C. decalin is preferably 0.5 to 5.0 dL / g.

Here, the ultimate viscosity [η] is more preferably in the range of 1.0 to 4.0 dL / g, and further preferably in the range of 1.2 to 3.5 dL / g.
The value of the ultimate viscosity [η] can be adjusted by the amount of hydrogen added during the polymerization when the 4-methyl-1-pentene polymer (A1) is produced.

The 4-methyl-1-pentene polymer (A1) having a value of the ultimate viscosity [η] in the above range shows good fluidity during the production of the resin composition and various moldings, and 4-methyl-1 -The dispersibility in the penten copolymer (A2) is improved, which is preferable in the appearance of the obtained multilayer biaxially stretched film.

[Method for producing 4-methyl-1-pentene polymer (A1)]
The 4-methyl-1-pentene polymer (A1) may be produced by polymerizing olefins, or may be produced by thermally decomposing a high molecular weight 4-methyl-1-pentene polymer. good. Further, it may be purified by a method such as solvent separation which separates by the difference in solubility in a solvent, or molecular distillation which separates by the difference in boiling point.

In the case of production by a polymerization reaction, for example, by adjusting the amount of 4-methyl-1-pentene and α-olefin to be copolymerized if necessary, the type of polymerization catalyst, the polymerization temperature, the amount of hydrogenation during polymerization, etc. , The melting point, stereoregularity, molecular weight, etc. of the obtained 4-methyl-1-pentene polymer (A1) are controlled. The method for producing by the polymerization reaction may be a known method. For example, it can be produced by a method using a known catalyst such as a Chigra natta catalyst or a metallocene catalyst.
The polymer (A1) may be a commercially available polymer such as TPX manufactured by Mitsui Chemicals, Inc., in addition to the polymer produced as described above.

[4-Methyl-1-pentene copolymer (A2)]
The 4-methyl-1-pentene copolymer (A2) satisfies the following requirements (A2-I) to (A2-II).

<Requirements (A2-I)>
The 4-methyl-1-pentene copolymer (A2) contains the structural unit (P) derived from 4-methyl-1-pentene in a proportion of 65 mol% or more and less than 96 mol%, and 4-methyl-1-pentene. It has a structural unit (BQ) derived from an α-olefin having 2 or more and 20 or less carbon atoms other than penten in a proportion of more than 4 mol% and 35 mol% or less.

The content of the structural unit (P) is 65 mol% or more and less than 96 mol%, preferably 68 mol% or more and less than 92 mol%, more preferably 68 mol% or more and less than 90 mol%, and particularly preferably. Is 80 mol% or more and less than 88 mol%.

When the content of the structural unit (P) is 65 mol% or more, the heat resistance is excellent, and the gloss of the film obtained with excellent compatibility with the polymer (A1) is excellent.
The content of the constituent unit (BQ) (when the constituent unit (BQ) is two or more, the total content of the two or more) is more than 4 mol% and 35 mol% or less, preferably 8 mol. It is more than% and 32 mol% or less, more preferably more than 10 mol% and 32 mol% or less, and particularly preferably more than 12 mol% and 20 mol% or less.

When the content of the structural unit (BQ) in the 4-methyl-1-pentene copolymer (A2) exceeds 4 mol%, the interlayer strength of the obtained laminated film is excellent and it becomes difficult to delaminate. Examples of α-olefins having 2 or more and 20 or less carbon atoms other than 4-methyl-1-pentene forming the structural unit (BQ) include ethylene, propylene, 1-butene, 1-hexene, 1-octene, and 1-decene. , 1-Hexadecene and 1-octadecene are preferable, α-olefins having 2 to 4 carbon atoms, that is, ethylene, propylene and 1-butene are more preferable, and propylene is particularly preferable.

Further, the structural unit (BQ) may be the same as or different from the structural unit (AQ) when the polymer (A 1) contains the structural unit (AQ).
The 4-methyl-1-pentene copolymer (A2) is other than the structural unit (P) derived from 4-methyl-1-pentene and 4-methyl-1-pentene as long as the effects of the present invention are not impaired. It may contain other structural units other than the structural unit (BQ) derived from α-olefin having 2 or more and 20 or less carbon atoms. The content of the other structural units is, for example, 0 to 10 mol%.

Examples of the monomer forming the other structural unit include cyclic olefins, aromatic vinyl compounds, conjugated diene, non-conjugated polyenes, functional vinyl compounds, hydroxyl group-containing olefins, halogenated olefins and the like.

As the cyclic olefin, aromatic vinyl compound, conjugated diene, non-conjugated polyene, functional vinyl compound, hydroxyl group-containing olefin, and halogenated olefin, for example, the compounds described in paragraphs 0034 to 0041 of JP2013-169685A are used. be able to.

Vinyl cyclohexane and styrene are particularly preferable as the monomers forming the other structural units.
When the 4-methyl-1-pentene copolymer (A2) contains the other structural units, only one of the other structural units may be contained, or two or more of the other structural units may be contained. You may.

The value of the content (mol%) of each structural unit in the 4-methyl-1-pentene copolymer (A2) ^{was measured by the measurement method by 13} C-NMR, and the specific measurement method is described in the section of Examples. As described in.

<Requirements (A2-II)>
The melting point (Tm) of the 4-methyl-1-pentene copolymer (A2) is not observed or is in the range of 100 ° C to 199 ° C, more preferably not observed, or is in the range of 110 ° C to 180 ° C. It is more preferably in the range of 110 ° C. to 160 ° C., and particularly preferably in the range of 125 ° C. to 150 ° C.

The melting point (Tm) of the 4-methyl-1-pentene copolymer (A2) is a value measured by the same method as the melting point (Tm) of the polymer (A1).
The 4-methyl-1-pentene copolymer (A2) preferably satisfies one or more of the following requirements in addition to the above requirements (A2-I) to (A2-II).

<Requirements (A2-III)>
The ultimate viscosity [η] of the 4-methyl-1-pentene copolymer (A2) measured at 135 ° C. in a decalin solvent is 0.5 to 4.0 dl / g, preferably 0.5 dl / g. It is g to 3.5 dl / g, more preferably 1.0 dl / g to 3.5 dl / g. When the ultimate viscosity [η] of the 4-methyl-1-pentene copolymer (A2) is within the above range, it is preferable from the viewpoint of moldability.
The ultimate viscosity [η] of the 4-methyl-1-pentene copolymer (A2) is a value measured by the same method as the ultimate viscosity [η] of the polymer (A1).

<Requirements (A2-IV)>
The molecular weight distribution (Mw / Mn) of the 4-methyl-1-pentene copolymer (A2) is preferably 1.0 to 3.5, preferably 1.1 to 3.0.
The weight average molecular weight (Mw) of the 4-methyl-1-pentene copolymer (A2) is preferably 1 × 10 ⁴ to 2 × 10 ⁶ from the viewpoint of moldability of the layer composed of the composition, which is more preferable. Is 1 × 10 ⁴ to 1 × 10 ⁶ .
The weight average molecular weight (Mw) and the molecular weight distribution (Mw / Mn) of the 4-methyl-1-pentene copolymer (A2) are values calculated by the method described in Examples.

<Requirements (A2-V)>
The melt flow rate (MFR) of the 4-methyl-1-pentene copolymer (A2), measured at 230 ° C. under a load of 2.16 kg according to ASTM D1238, is the fluidity of the composition during molding. From the viewpoint of, it is preferably 0.1 g / 10 minutes to 100 g / 10 minutes, more preferably 0.5 g / 10 minutes to 50 g / 10 minutes, and further preferably 0.5 g / 10 minutes to 30 g / 10. Minutes.

[Method for producing 4-methyl-1-pentene copolymer (A2)]
The 4-methyl-1-pentene copolymer (A2) is prepared by a conventionally known metallocene catalyst system, for example, International Publication No. 2005/121192, International Publication No. 2011/055803, International Publication No. 2014/050817, etc. It can be synthesized by the method described in.

[Other resins]
The resin composition constituting the A layer of the multilayer biaxially stretched film of the present invention contains the above-mentioned 4-methyl-1-pentene polymer (A1) and 4-methyl within a range not impairing the object of the present invention. It may contain other resins other than -1-pentene copolymer (A2). As other resins, for example, polyolefin-based polymers such as polyethylene, polypropylene, poly1-butene, styrene-based resin, and ethylene / α-olefin copolymer can be added. The content of the other resin is preferably 20% by mass or less, more preferably 10% by mass or less, still more preferably 5% by mass or less, based on the total mass of the A layer.

〔Additive〕
The resin composition constituting the A layer of the multilayer biaxially stretched film of the present invention comprises a specific amount of 4-methyl-1-pentene polymer (A1) and a specific amount of 4-methyl-1-pentene copolymer (A1). As long as it contains A2) and does not impair the object of the present invention, for example, a weather-resistant stabilizer, a heat-resistant stabilizer, an antioxidant, an ultraviolet absorber, an antioxidant, an anti-slip agent, an anti-blocking agent, Antifogging agents, nucleating agents, lubricants, pigments, dyes, antioxidants, hydrochloric acid absorbers, inorganic or organic fillers, organic or inorganic foaming agents, cross-linking agents, cross-linking aids, adhesives, softeners, It may contain various additives such as flame retardant.

Even if the resin composition constituting the A layer in the present invention contains a nucleating agent which is a specific optional component in order to further improve the moldability, that is, to raise the crystallization temperature and accelerate the crystallization rate. good. In this case, for example, the nucleating agent is dibenzylidene sorbitol-based nucleating agent, phosphate ester salt-based nucleating agent, rosin-based nucleating agent, benzoate metal salt-based nucleating agent, fluorinated polyethylene, 2,2-methylenebis (4,6-di). -T-Butylphenyl) Sodium phosphate, pimelli acid or a salt thereof, dicyclohexylamide 2,6-naphthalene acid dicarboxylic acid, etc. The blending amount is not particularly limited, but is 0. It is preferably about 1 to 1 part by mass. There is no particular limitation on the compounding timing, and it can be added during polymerization, after polymerization, or during molding.

The resin composition may contain a secondary antioxidant, a heat-resistant stabilizer, a weather-resistant stabilizer, an antistatic agent, a slip agent, an antifogging agent, a lubricant, and the like, as long as the object of the present invention is not impaired. Dyes, pigments, natural oils, synthetic oils, waxes, fillers, hydrochloric acid absorbers, other olefin polymers and the like can be blended. The blending amount is not particularly limited, but is usually 0 to 50 parts by mass, preferably 0 to 30 parts by mass, further preferably 0 to 10 parts by mass, and 0 to 1 part by mass with respect to 100 parts by mass of the resin composition. Is particularly preferable.

As the antioxidant, a known antioxidant can be used. Specifically, a hindered phenol compound, a sulfur-based antioxidant, a lactone-based antioxidant, an organic phosphite compound, an organic phosphonite compound, or a combination of several kinds thereof can be used.

Examples of the lubricant include saturated or unsaturated fatty acids such as lauric acid, palmitic acid, oleic acid and stearic acid and their sodium, calcium and magnesium salts, which may be used alone or in combination of two or more. Can be done. The blending amount of the lubricant is usually preferably 0.1 to 3 parts by mass, more preferably 0.1 to 2 parts by mass with respect to 100 parts by mass of the resin composition.

As the slip agent, it is preferable to use amides of saturated or unsaturated fatty acids such as lauric acid, palmitic acid, oleic acid, stearic acid, erucic acid and hebenic acid, or bisamides of these saturated or unsaturated fatty acids. Of these, erucic acid amides and ethylene bisstearoamides are particularly preferred. These fatty acid amides are usually preferably blended in the range of 0.01 to 5 parts by mass with respect to 100 parts by mass of the resin composition according to the present invention.

When the layer A according to the present invention contains the optional component other than the component (A1) and the component (A2), the mass obtained by subtracting the optional component from the total mass of the layer A is set to 100% by mass, and the component is defined as 100% by mass. The (A1) content definition (5 to 95% by mass) and the component (A2) content (5 to 95% by mass) definition are applied.

≪B layer≫
The B layer in the multilayer biaxially stretched film of the present invention is a layer provided to impart excellent mechanical properties to the multilayer biaxially stretched film of the present invention. The B layer is preferably formed from a resin composition containing polypropylene (B1). The polypropylene (B1) is a known polymer mainly composed of propylene, and examples thereof include a propylene homopolymer and a propylene / α-olefin copolymer (propylene) of propylene and an α-olefin other than propylene. -Random copolymers such as ethylene copolymers, propylene / 1-butene copolymers, propylene / ethylene / 1-butene copolymers, block copolymers, or mixtures thereof) and the like can be mentioned. Isotactic polypropylene and syndiotactic polypropylene are preferably used as the polypropylene, and the isotactic mesopendad fraction (mm mm) or syndiotactic mesopendad fraction (rrrr) showing stereoregularity is 90% or more. It is preferably 92% or more, more preferably 93% or more. When the stereoregularity is high, the crystallinity of the resin is improved, and high thermal stability and mechanical properties can be imparted.

The copolymerization ratio of α-olefin in the propylene / α-olefin copolymer is preferably 5% by mass or less. Further, the propylene / α-olefin copolymer may be a random copolymer or a block copolymer, and may contain a nucleating agent (crystallization nucleating agent). The nucleating agent is not particularly limited, and various inorganic compounds, various carboxylic acids or metal salts thereof, dibenzylidene sorbitol-based compounds, aryl phosphate-based compounds, cyclic polyvalent metal aryl phosphate-based compounds and aliphatic monocarboxylic acid alkalis. Examples thereof include metal salts or mixtures with basic aluminum, lithium, hydroxy, carbonate and hydrate, and α-crystal nucleating agents such as various polymer compounds. These crystallization nucleating agents can be used alone or in combination of two or more materials.

The MFR of polypropylene (B1) can be measured according to JIS K7210. Specifically, under the measurement conditions of a temperature of 230 ° C. and a load of 2.16 kg, it is preferably 0.5 to 25 g / 10 minutes, more preferably 1 to 15 g / 10 minutes, and 2 to 10 g / 10 minutes. It is more preferably 10 minutes. When the MFR of polypropylene (B1) is in the above range, it is suitable for extrusion molding.

The ash content caused by the polymerization catalyst residue and the like contained in polypropylene (B1) is preferably as small as possible and preferably 50 ppm or less in order to reduce minute foreign substances (fish eyes). More preferably, it is 40 ppm or less.

Further, the same heat stabilizer, antioxidant, slip agent, chlorine trapping agent, antistatic agent and the like as those blended in the resin composition forming the A layer are added to the resin composition forming the B layer. May be.

≪Multilayer biaxially stretched film≫
The layer structure of the multilayer biaxially stretched film of the present invention includes a two-layer structure in which A layer and B layer are laminated, a three-layer structure in which A layer / B layer / A layer are laminated in this order, A layer and B layer. Compositions containing C layer different from any of the above (for example, ethylene-modified isotactic polypropylene resin (random copolymer or block copolymer), atactic polypropylene, syndiotactic polypropine, etc., olefin polymer, styrene polymer, acrylic Examples thereof include a three-layer structure in which layers formed from a pressure-sensitive adhesive material exhibiting adhesiveness obtained from a system polymer or the like) are laminated in the order of A layer / B layer / C layer. From the viewpoint of moldability at the time of lamination, a two-layer structure of A layer / B layer or a three-layer structure of A layer / B layer / A layer is preferable.

The method for obtaining such a multilayer film is not particularly limited, but usually, first, a raw film (also referred to as a raw sheet) in which layers A and B and, if necessary, other layers are laminated. Is then formed and then the raw film is biaxially stretched. The method of forming the raw film is, for example, a method of laminating a surface layer film previously obtained by T-die molding or inflation molding by a known laminating method such as extrusion lamination or extrusion coating, or a method of laminating a plurality of films independently. Then, each film is laminated by dry lamination, etc., but from the viewpoint of productivity, coextrusion molding in which a plurality of components are subjected to a multi-layer extruder is preferable.

The thickness of the unstretched film according to the present invention, that is, the raw film, is not particularly limited, but is usually 100 μm to 1000 μm, preferably 150 to 800 μm, and more preferably 200 to 500 μm.

The total thickness of the multilayer biaxially stretched film of the present invention is preferably 3 to 60 μm, more preferably 10 to 50 μm, and even more preferably 20 to 50 μm. When the total thickness of the film is 3 to 60 μm, a film having excellent mechanical properties and stretchability can be obtained.

The thickness of one layer A in the multilayer biaxially stretched film of the present invention is preferably 2 to 250%, more preferably 25 to 200%, based on the thickness of one layer B. When the multilayer biaxially stretched film of the present invention contains two or more A layers, the thickness of each A layer may be the same or different from each other.

The tape peeling force of the multilayer biaxially stretched film of the present invention at a peeling speed of 300 mm / min is preferably 7N / 50 mm or less. More preferably, it is 1 to 6.5 N / 50 mm. The tape peeling force can be adjusted by melting point and the amount of 4-methyl-1-pent emissions based polymer (A 1). The tape peeling force is measured according to the adhesive sheet test method (JIS Z0237-2000). As a specific example of the measurement method, an acrylic adhesive material (manufactured by Nitto Denko Corporation, trade name Nitto Tape 31B) is used as the adhesive material, and the test film and the adhesive tape cut into a width of 50 mm and a length of 100 mm are heated at a temperature of 23 ° C. After leaving the adhesive film in an environment of 50% relative humidity for 1 hour, the adhesive film is passed through 2 reciprocations while applying pressure with a rubber roll of about 2 kg to be attached to the test plate. After pasting, it is left in a constant environment with a temperature of 23 ° C or 50 ° C and a relative humidity of 50% for one day, and then peeled off in an environment of a temperature of 23 ° C and a relative humidity of 50% in the 180 ° direction at a speed of 300 mm / min. It can be evaluated by measuring the peeling force at the time.

The 45 ° gloss of the multilayer biaxially stretched film of the present invention is preferably 70% or more. More preferably, it is 80% or more. The upper limit is not particularly limited, but is usually 130% or less. The method for measuring the 45 ° gloss is as described in the section of Examples in detail.

≪Manufacturing method of multilayer biaxially stretched film≫
Various known methods for preparing resin composition pellets for the A layer or the B layer by mixing each component include, for example, a multi-stage polymerization method, a plast mill, a Henschel mixer, a V-blender, a ribbon blender, and a tumbler. , A method of mixing with a blender, a kneader luder, etc., or a method of granulating or crushing after mixing with a uniaxial extruder, a twin screw extruder, a kneader, a Banbury mixer, etc., for example, after melt-kneading at 180 to 300 ° C. can do. By this method, high quality resin composition pellets in which each component and additive are uniformly dispersed and mixed can be obtained.

The raw sheet for the multilayer biaxially stretched film of the present invention can be obtained by melt-extruding the above-mentioned resin composition pellets in a cylinder temperature usually in the range of 180 to 300 ° C.
In order to produce a multilayer biaxially stretched film from the raw sheet, it is possible to perform batch biaxial stretching, sequential biaxial stretching immediately after cast molding, or simultaneous biaxial stretching. In the sequential biaxial stretching, the cast raw sheet is maintained at 100 to 165 ° C., passed between rolls provided with a speed difference, stretched 2 to 5 times in the flow direction, and immediately cooled to room temperature. Next, the film is guided to a tenter, stretched 5 to 10 times in the width direction at a temperature of 150 ° C. or higher, relaxed, heat-fixed, and wound.

≪Use≫
Specific applications of the multilayer biaxially stretched film of the present invention include, for example, general film applications such as the following.
Packaging films; for example, food packaging films, stretch films, wrap films, shrink films, easy peel films, aluminum vapor deposition films, PVDC coated films, and the like. Breathable film; for example, paper diapers, sanitary goods, surgical gowns, surgical gloves, surgical down, house wraps (moisture permeable waterproof sheets), disposable body warmers, household dehumidifiers, desiccants, oxygen scavengers, freshness preservatives, compost Examples include chemical sheets and simple jumpers. Anti-rust film; for example, transportation and packaging of automobile parts, knockdown parts, machine / machine parts, iron / chrome products, steel pipes, wire rods, bolts and nuts, bearings, dies, tools, cutlery, cutting tools, building tools, etc. Storage packaging, export packaging, etc. can be mentioned. Anti-fog film; for example, a film for fruits and vegetables, a film for processed foods, and the like.

Directional film; twisted wrapping of confectionery, agricultural materials, laminated base material, coin wrapping, wire bundling material, fruit and vegetable wrapping, corrugated cardboard cut tape, detergent refill container, rice wrapping, pillow wrapping, stick wrapping, boiled retort wrapping, Examples include water-based food packaging and infusion bags.

Self-cleaning films; for example, road signs, general signs, signboards, windowpanes, road materials, side mirrors and the like.
Separator; For example, battery separator, separator for lithium ion battery, electrolyte membrane for fuel cell, adhesive / adhesive separator.
Stretched film; for example, a film for a film capacitor, a capacitor film, a capacitor film for a fuel cell.
Semiconductor process film; for example, dicing tape, back grind tape, die bonding film, polarizing plate film, surface protective film; for example, polarizing plate protective film, liquid crystal panel protective film, optical component protective film, lens protective film , Protective film for electrical parts and electrical appliances, Protective film for mobile phones, Protective film for personal computers, Masking film, Protective film for touch panel.

Films for electronic members; for example, diffusion films, reflective films, radiation resistant films, gamma ray resistant films, porous films.
Building material films; for example, window films for building materials, films for laminated glass, bulletproof materials, films for bulletproof glass, heat shield sheets, heat shield films, and the like.
Transfer film; For example, automobile / industrial transfer film, packaging transfer film.
Release film; for example, release film for flexible printed substrate (FPC), release film for ACM substrate, release film for rigid flexible substrate, release film for advanced composite material, release film for curing carbon fiber composite material, Release film for curing glass fiber composites, release film for curing aramid fiber composites, release film for curing nanocomposites, release film for curing filler fillers, release film for semiconductor encapsulation, release for polarizing plates Mold film, release film for diffusion sheet, release film for prism sheet, release film for reflection sheet, cushion film for release film, release film for fuel cell, release film for various rubber sheets, release for urethane curing Examples thereof include a mold film and a release film for curing epoxy (manufacturing process members such as metal bats and golf clubs).

Particularly preferably, a release film used for a surface protective film, an adhesive tape, or the like, a release liner or separator film, a transfer film, a carrier at the time of manufacturing a composite material, and the like can be mentioned. Particularly preferably, it is used as a transfer film.

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 examples, each physical property was measured as follows.
〔composition〕
The content (mol%) of 4-methyl-1-pentene and α-olefin in the polymer ^{was measured by 13} C-NMR. The measurement conditions are as follows.
-Measuring device: Nuclear magnetic resonance device (ECP500 type, manufactured by JEOL Ltd.)
・ Observation nucleus: ¹³ C (125 MHz)
-Sequence: Single pulse proton decoupling-Pulse width: 4.7 μsec (45 ° pulse)
・ Repeat time: 5.5 seconds ・ Cumulative number: 10,000 times or more ・ Solvent: Ortodichlorobenzene / deuterated benzene (volume ratio: 80/20) mixed solvent ・ Sample concentration: 55 mg / 0.6 mL
-Measurement temperature: 120 ° C
-Chemical shift reference value: 27.50 ppm

[Melting point (Tm)]
The melting point (Tm) of the polymer was measured using a differential scanning calorimeter (DSC220C type, manufactured by Seiko Instruments Inc.) as a measuring device.
About 5 mg of the polymer was sealed in a measuring aluminum pan and heated from room temperature to 280 ° C. at 10 ° C./min. The copolymer was held at 280 ° C. for 5 minutes and then cooled to −50 ° C. at 10 ° C./min to completely melt the copolymer. After standing at −50 ° C. for 5 minutes, the second heating was performed at 10 ° C./min to 280 ° C. The peak temperature (° C.) at the second heating was defined as the melting point (Tm) of the polymer.

[Ultimate viscosity [η]]
The ultimate viscosity [η] of the polymer was measured at 135 ° C. in a decalin solvent using an Ubbelohde viscometer as a measuring device. Specifically, after dissolving about 20 mg of a powdery copolymer in 25 ml of decalin, the specific viscosity η _sp was measured in an oil bath at 135 ° C. using an Ubbelohde viscometer. After adding 5 ml of decalin to this decalin solution and diluting it, the specific viscosity η _sp was measured in the same manner as above. _{This dilution operation was repeated twice more, and the value of η sp} / C when the concentration (C) was extrapolated to 0 was determined as the ultimate viscosity [η] (unit: dl / g) (see Equation 1 below). ..
[Η] = lim (η _sp / C) (C → 0) ・ ・ ・ Equation 1

[Melt flow rate (MFR)]
The melt flow rate (MFR: Melt Flow Rate) of the polymer is JIS.
According to K7210, the copolymers A2 (A2-1 and A2-1) and polypropylene were measured at 230 ° C. under a load of 2.16 kg. The unit is g / 10 minutes. The polymer A1 (A1-1) was measured at 260 ° C. under a load condition of 5.0 kg.
〔density〕
The density of the polymer was measured according to JIS K7112 (density gradient tube method).

[Production Example 1] Production of 4-methyl-1-pentene polymer (A1-1)
Table 1 by changing the proportions of 4-methyl-1-pentene, 1-hexadecene, 1-octadecene, and hydrogen according to the polymerization method described in Comparative Example 7 and Comparative Example 9 of International Publication No. 2006/054613. A 4-methyl-1-pentene polymer A1-1 having the physical properties shown in the above was obtained.

[Production Example 2] Production of 4-methyl-1-pentene copolymer (A2-1)
300 ml of n-hexane (dried on activated alumina in a dry nitrogen atmosphere) and 450 ml of 4-methyl-1-pentene were placed in a SUS autoclave with a stirring blade having a capacity of 1.5 L and sufficiently nitrogen-substituted. After charging at 23 ° C., 0.75 ml of a 1.0 mmol / ml toluene solution of triisobutylaluminum (TIBAL) was charged, and the stirrer was rotated.

Next, the autoclave was heated to an internal temperature of 60 ° C. and pressurized with propylene so that the total pressure (gauge pressure) was 0.19 MPa.
Subsequently, 1 mmol of methylaluminoxane in terms of Al and 0.01 mmol of diphenylmethylene (1-ethyl-3-t-butyl-cyclopentadienyl) (2,7-di-t-) prepared in advance. 0.34 ml of a toluene solution containing butyl-fluorenyl) zirconium dichloride was press-fitted into an autoclave with nitrogen to initiate a polymerization reaction. During the polymerization reaction, the temperature was adjusted so that the internal temperature of the autoclave was 60 ° C.

60 minutes after the start of polymerization, 5 ml of methanol was press-fitted into the autoclave with nitrogen to stop the polymerization reaction, and then the inside of the autoclave was depressurized to atmospheric pressure. After decompression, acetone was added to the reaction solution while stirring the reaction solution to obtain a polymerization reaction product containing a solvent. Next, the obtained polymerization reaction product containing the solvent was dried under reduced pressure at 130 ° C. for 12 hours to obtain 44.0 g of a powdery polymer A2-1 as the copolymer (B). Table 1 shows the measurement results of various physical properties.

[Production Example 3] Production of 4-methyl-1-pentene copolymer (A2-2)
300 ml of n-hexane (dried on activated alumina in a dry nitrogen atmosphere) and 450 ml of 4-methyl-1-pentene were placed in a SUS autoclave with a stirring blade having a capacity of 1.5 L and sufficiently nitrogen-substituted. It was charged at 23 ° C. 0.75 ml of a 1.0 mmol / ml toluene solution of triisobutylaluminum (TIBAL) was charged into this autoclave, and the stirrer was rotated.

Next, the autoclave was heated to an internal temperature of 60 ° C. and pressurized with propylene so that the total pressure (gauge pressure) was 0.40 MPa.
Subsequently, 1 mmol of methylaluminoxane in terms of Al and 0.01 mmol of diphenylmethylene (1-ethyl-3-t-butyl-cyclopentadienyl) (2,7-di-t-) prepared in advance. 0.34 ml of a toluene solution containing butyl-fluorenyl) zirconium dichloride was press-fitted into an autoclave with nitrogen to initiate a polymerization reaction. During the polymerization reaction, the temperature was adjusted so that the internal temperature of the autoclave was 60 ° C.

60 minutes after the start of polymerization, 5 ml of methanol was press-fitted into the autoclave with nitrogen to stop the polymerization reaction, and then the inside of the autoclave was depressurized to atmospheric pressure. After decompression, acetone was added to the reaction solution while stirring the reaction solution to obtain a polymerization reaction product containing a solvent.
Next, the obtained polymerization reaction product containing the solvent was dried under reduced pressure at 100 ° C. for 12 hours to obtain 36.9 g of a powdery copolymer A2-2. Table 1 shows the measurement results of various physical properties.

[Example 1]
A three-layer biaxially stretched film formed by laminating in the order of A layer / B layer / A layer was formed. First, as the resin composition forming the A layer, the polymer A1-1: 20 parts by mass and the copolymer A2-1: 80 parts by mass are supplied to the twin-screw extruder and kneaded at 270 ° C. The resin composition was prepared and used as a raw material for the A layer. The resin forming the B layer is polypropylene (Prime Polypro (registered trademark) F113G (Homopolymer of propylene, density: 910 kg / m ³ , MFR (230 ° C): 3.0 g / 10 minutes, manufactured by Prime Polymer Co., Ltd.). )) Was used.

The obtained resin composition and resin were subjected to the cylinder temperature of layer A by using a three-kind three-layer T-die sheet molding machine in which a T-die having a lip width of 330 mm was installed and three hopper inlets and a 30 mmφ screw were installed. Set the cylinder temperature of the B layer to 230 ° C and the die temperature to 270 ° C, extrude the melt-kneaded product from the T die with a thickness of 300 μm (A layer 50 μm / B layer 200 μm / A layer 50 μm), and cast molding. The original film of Example 1 was obtained. The thickness of each layer was calculated from the extrusion amount.

Next, using a batch-type biaxial stretching machine KARO IV manufactured by Brookner, preheating temperature 162 ° C., preheating time 2 minutes, stretching temperature 162 ° C., stretching speed 100% / sec stretching conditions, heat setting conditions 162 ° C., 30 seconds. The obtained raw film was stretched 3 times in the flow direction (MD) and 5 times in the width direction (TD) to obtain a multilayer biaxially stretched film having a total film thickness of 20 μm.
The evaluation results of the obtained multilayer biaxially stretched film are shown in Table 2. The specific test method is as follows.

[Delami during stretching]
The peeling between the layers A and B of the multi-layer biaxially stretched film after the multi-layer biaxially stretched film was visually confirmed, and the presence or absence of delamination was confirmed.

[Homogeneity after stretching]
The multi-layer biaxially stretched film after biaxial stretching was visually confirmed, and was marked with ◯ when the surface was smooth and uniform, and x when there were non-uniform parts such as wrinkles.

[Gloss (gloss)]
The multi-layer biaxially stretched film after biaxial stretching was measured according to JIS Z8741 under the conditions of an incident angle of 45 ° and a light receiving angle of 45 °, and the average value of the data of 5 points was taken as the glossiness.

[Example 2, Comparative Examples 1 to 4]
The resin composition forming the A layer was prepared by mixing (dry blending) at the ratio shown in Table 2. Further, a multilayer biaxially stretched film was obtained by the same method as in Example 1 except that the thickness of each layer was changed as shown in Table 2. The evaluation results of the obtained multilayer biaxially stretched film are shown in Table 2.

[Comparative Example 5]
A biaxially stretched film was prepared by using the polymer A1-1 alone in the A layer with the compositions shown in Table 2.

Claims (5)

A multi-layer biaxially stretched film in which layers A and B are laminated.
The A layer is composed of a resin composition containing a 4-methyl-1-pentene polymer (A1) and a 4-methyl-1-pentene copolymer (A2).
The content of the 4-methyl-1-pentene polymer (A1) in the A layer is 5% by mass or more and 50% by mass or less with respect to the total mass of the A layer, and both 4-methyl-1-pentene are used. The content of the polymer (A2) is 50% by mass or more and 95% by mass or less with respect to the total mass of the A layer.
Moreover, the 4-methyl-1-pentene polymer (A1) satisfies the following requirements (A1-I) to (A1-II), and the 4-methyl-1-pentene copolymer (A2) meets the following requirements (A2). A2-I) meets - the (A2-II),
The B layer is formed from a resin composition containing polypropylene (B1).
Multi-layer biaxially stretched film.
It contains 90 mol% to 100 mol% of a structural unit derived from (A1-I) 4-methyl-1-pentene.
The melting point (Tm) measured by (A1-II) DSC is in the range of 200 ° C. to 250 ° C.
The content of the structural unit (P) derived from (A2-I) 4-methyl-1-pentene is 65 mol% or more and less than 96 mol%, and the α-olefin (4-methyl-) having 2 to 20 carbon atoms. The content of the structural unit (BQ) derived from 1-pentene) is more than 4 mol% and 35 mol% or less.
(A2-II) The melting point (Tm) measured by DSC is not observed or is in the range of 100 ° C to 199 ° C. The multilayer biaxially stretched film according to claim 1, wherein the 4-methyl-1-pentene polymer (A1) further satisfies the following requirement (A1-III).
(A1-III) The ultimate viscosity [η] measured in 135 ° C. decalin is 0.5 to 5.0 dl / g. The 4-methyl-1-pentene copolymer polymer (A2) further satisfies the following requirement (A2-III), the multilayer biaxially oriented film according to claim 1 or 2.
(A2-III) The ultimate viscosity [η] measured in 135 ° C. decalin is 0.5 to 4.0 dl / g. The layer structure is a three-layer structure of A layer / B layer / A layer or A layer / B layer / C layer (here, C layer is a layer different from both A layer and B layer). The multilayer biaxially stretched film according to any one of claims 1 to 3. The multilayer biaxially stretched film according to any one of claims 1 to 4 , wherein the multilayer biaxially stretched film is a transfer film.