JP2017109371A - Biaxially oriented release film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a biaxially oriented polypropylene film excellent in surface smoothness, transparency, and releasability.SOLUTION: The problem is solved by a film comprising a resin composition comprising 4-methyl-1-pentene based copolymer (A1) and polypropylene (B) in one layer, where the 4-methyl-1-pentene based copolymer (A1) content is 5 mass% or more and 95 mass% or less relative to the total mass, the polypropylene (B) content is 5 mass% or more and 95 mass% or less relative to the total mass, and the 4-methyl-1-pentene based copolymer (A1) satisfies [1] below: [1] being a copolymer comprising 96 mol%-80 mol% of a constitutional unit derived from 4-methyl-1-pentene, and 4 mol%-20 mol% of a constitutional unit derived from a α-olefin having a carbon number of 2-20 (the total of the constitutional unit derived from 4-methyl-1-pentene and the constitutional unit derived from a α-olefin having a carbon number of 2-20 is 100 mol%).SELECTED DRAWING: None

Description

  The present invention relates to a biaxially stretched polypropylene film excellent in releasability. In particular, the present invention relates to a biaxially stretched polypropylene film that is excellent in releasability by including a 4-methyl-1-pentene copolymer in the release layer and does not generate delamination during biaxial stretching. More specifically, the present invention relates to a biaxially stretched polypropylene film useful for a release film, a release liner, a separator film, and the like.

  In general, resin materials, metal products, glass products, and the like for building materials and optical materials are attached with a surface protective film on the surface to prevent surface scratches and foreign matter from being transported, stored or processed. In addition to properties such as flexibility and mechanical properties, the surface protective film is required to have various properties according to the object to be protected, the purpose of protection, the use environment, and the like. For this reason, the development of surface protective films has been promoted from various viewpoints. For example, a surface protective film mainly composed of a polyethylene component (Patent Document 1) and a surface protective film made 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 films are widely used as packaging and industrial material films because they are excellent in light weight, thermal stability and mechanical properties. In recent years, it has been widely used as a non-silicone release material as a film for manufacturing electronic components, electronic substrates, and thermosetting materials such as fiber reinforced plastics, but further improvements have been demanded. . As a method for improving releasability, for example, the release force can be further increased by blending a polymethylpentene polymer with polypropylene (Patent Documents 3 and 4). However, it is known that the biaxial stretchability is deteriorated by increasing the polymethylpentene content, and it is known that delamination occurs in the case of a multilayer film, and the α-olefin copolymer is blended as a compatibilizer. Has been proposed (Patent Document 5).

  The inventors of the present application have already disclosed a release film comprising a poly-4methyl-1-pentene copolymer, which is excellent in releasability and has 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 film transparency tends to deteriorate (Patent Document 6).

  As described above, in recent years, development of a film having excellent workability such as biaxial stretching, excellent appearance, and good releasability has been demanded.

JP 2006-116769 A JP 2010-275340 A JP 2008-189795 A JP-A-7-070384 JP2015-120331A JP 2014-12596 A

  The present inventors provide a film having a low moldable temperature, excellent releasability and excellent transparency, a surface protection film containing the film, and a resin composition suitable for the production of the film. With the goal.

As a result of intensive studies to solve the above problems, the present inventors have found that a biaxially stretched film containing a 4-methyl-1-pentene copolymer having specific physical properties can solve the above problems, and has a low moldable temperature. The present inventors have found that the film can be stretched without causing the delamination phenomenon of the multilayer film that is sometimes encountered in the prior art, even under the conditions, and has been completed.
That is, the gist of the present invention is as follows.

<< 1 >> A biaxially stretched polypropylene film in which an A layer and a B layer are laminated,
A layer is composed of a resin composition containing 4-methyl-1-pentene copolymer (A1) and polypropylene (A2),
The content of the 4-methyl-1-pentene copolymer (A1) is 5% by mass to 95% by mass with respect to the total mass of the A layer, and the content of the polypropylene (A2) is A layer. 5 mass% or more and 95 mass% or less with respect to the total mass of (the total of component (A1) and component (A2) is 100 mass%), and the 4-methyl-1-pentene copolymer A film in which (A1) satisfies the following requirement [1].
[1] 96 to 80 mol% of structural units derived from 4-methyl-1-pentene and structural units derived from olefins having 2 to 20 carbon atoms (excluding 4-methyl-1-pentene) The sum is 4 to 20 mol% (provided that the total of the structural units derived from 4-methyl-1-pentene and the structural units derived from olefins having 2 to 20 carbon atoms is 100 mol%).

<< 2 >> The biaxially stretched polypropylene film according to claim 1, wherein the 4-methyl-1-pentene copolymer (A1) satisfies all the following [2] to [5].
[2] Intrinsic viscosity [η] measured in decalin at 135 ° C. is 0.5 to 5.0 dl / g [3] Weight average molecular weight (Mw) and number average measured by gel permeation chromatography (GPC) Molecular weight distribution (Mw / Mn), which is a ratio to molecular weight (Mn), is 1.0 to 3.5 [4] Density is 825 to 860 kg / m ³ [5] Melting point (Tm) measured by DSC Is in the range of 100 ° C. to 199 ° C.

  << 3 >> The biaxially oriented polypropylene according to claim 1 or 2, wherein the 4-methyl-1-pentene copolymer (A1) has a melting point (Tm) measured by DSC in the range of 100 ° C to 180 ° C. the film.

  << 4 >> The B layer is formed of a resin composition containing polypropylene (B1) which may be the same as or different from the polypropylene (A2). Biaxially stretched polypropylene film.

  << 5 >> Layer configuration is a three-layer configuration of A layer / B layer / A layer or A layer / B layer / C layer (where C layer is a layer different from both A layer and B layer) It is a biaxially stretched film in any one of Claims 1-4 characterized by the above-mentioned.

  According to the present invention, there is provided a biaxially stretched polypropylene film that does not generate delamination or the like during biaxial stretching and is excellent in surface smoothness and releasability.

Hereinafter, specific embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and may be implemented with appropriate modifications within the scope of the object of the present invention. be able to. In addition, in this specification, the numerical range represented using "to" means the range which includes the numerical value described before and behind "to" as a lower limit and an upper limit.
In addition, in this specification, when referring to the amount of each component in the composition, when there are a plurality of substances corresponding to each component in the composition, the plurality present in the composition unless otherwise specified. Means the total amount of substances.

  The biaxially stretched release film containing the 4-methyl-1-pentene copolymer (A) according to the present invention will be described in detail below.

  The biaxially stretched polypropylene film of the present invention is formed by laminating an A layer and a B layer, and the A layer comprises a resin composition containing 4-methyl-1-pentene copolymer (A1) and polypropylene (A2). It is configured. Hereinafter, the A layer and the B layer will be described in detail, and then the layer configuration and the film manufacturing method will be described.

≪A layer≫
The A layer contains 4-methyl-1-pentene copolymer (A1) and polypropylene (A2).
[4-Methyl-1-pentene copolymer (A1)]

Hereinafter, the 4-methyl-1-pentene copolymer (A1) will be described.
The 4-methyl-1-pentene copolymer (A1) contains 96 to 80 mol% of structural units derived from 4-methyl-1-pentene and has 2 to 20 carbon atoms of olefin (4-methyl). The structural unit derived from (excluding -1-pentene) is contained in a proportion of 4 mol% to 20 mol%. The olefin having 2 to 20 carbon atoms is not limited to one type, and two or more types may be selected. When a plurality of olefins are selected, the above range may be satisfied as the sum of the structural units. .

  Here, from the viewpoint of heat resistance, transparency, and moldability, the upper limit of the structural unit derived from 4-methyl-1-pentene is preferably 96 mol%, and preferably 95 mol%. More preferably, it is more preferably 93 mol%. Further, the lower limit of the structural unit derived from 4-methyl-1-pentene is preferably 80 mol%, more preferably 83 mol%, and 84 mol%. Further preferred.

  On the other hand, the upper limit of the structural unit derived from an olefin having 2 to 20 carbon atoms (excluding 4-methyl-1-pentene) is preferably 20 mol%, more preferably 18 mol%. Preferably, 17 mol% is contained. The lower limit of the structural unit derived from an olefin having 2 to 20 carbon atoms (excluding 4-methyl-1-pentene) is preferably 4 mol%, and preferably 5 mol%. More preferably, it is more preferably 7 mol%. Here, the sum total of the structural unit of 4-methyl-1-pentene and a C2-C20 olefin is 100 mol%.

  By making the ratio of the structural units of 4-methyl-1-pentene and the olefin having 2 to 20 carbon atoms within the above range, the melting point of the copolymer (A1) obtained is as in the above requirement [5]. Can be adjusted. Therefore, when producing a film comprising a layer containing the copolymer (A1), compared with a conventionally used 4-methyl-1-pentene polymer, particularly a homopolymer of 4-methyl-1-pentene. The molding temperature can be lowered. Furthermore, it becomes possible to maintain the heat resistance of a copolymer (A) at a high level by making the ratio of a structural unit in the said range.

  The 4-methyl-1-pentene copolymer (A1) is derived from a 4-methyl-1-pentene structural unit chain and an olefin having 2 to 20 carbon atoms (excluding 4-methyl-1-pentene). It may be a block copolymer containing a block in which the same type of structural unit is continuous. From the viewpoint of transparency and moldability, a random copolymer of 4-methyl-1-pentene and an olefin having 2 to 20 carbon atoms is preferable.

  Examples of the olefin having 2 to 20 carbon atoms contained in the 4-methyl-1-pentene copolymer (A1) include ethylene, propylene, 1-butene, 1-pentene, 1-hexene, and 3-methyl-1- Preferred examples include butene, 3-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-eicocene and the like.

  From the viewpoint of physical properties of the obtained copolymer, ethylene, propylene, 1-butene, 1-hexene, 3-methyl-1-butene, 3-methyl-1-pentene, 1-octene, 1-decene, 1-decene, Hexadecene, 1-heptadecene and 1-octadecene are preferable, ethylene, propylene, 1-butene, 1-hexene, 1-octene, 1-decene, 1-hexadecene, 1-heptadecene and 1-octadecene are more preferable, and 1-octene. 1-decene, 1-hexadecene, 1-heptadecene, and 1-octadecene are more preferable. Of these, α-olefins having 2 to 4 carbon atoms are preferable, and specific examples include ethylene, propylene, and 1-butene.

  These olefins having 2 to 20 carbon atoms can be used alone or in combination of two or more. Furthermore, propylene is most preferable from the viewpoints of copolymerizability and dispersibility.

  The 4-methyl-1-pentene copolymer (A1) is a 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. A structural unit derived from a polymerizable compound other than (excluding pentene) (hereinafter also referred to as a polymerizable compound) may be included.

  Examples of the polymerizable compound include vinyl compounds having a cyclic structure such as styrene, vinylcyclopentene, vinylcyclohexane, and vinylnorbornane; vinyl esters such as vinyl acetate; unsaturated organic acids such as maleic anhydride or derivatives thereof. Conjugated dienes such as butadiene, isoprene, pentadiene and 2,3-dimethylbutadiene; 1,4-hexadiene, 1,6-octadiene, 2-methyl-1,5-hexadiene, 6-methyl-1,5-heptadiene 7-methyl-1,6-octadiene, dicyclopentadiene, cyclohexadiene, dicyclooctadiene, methylene norbornene, 5-vinyl norbornene, 5-ethylidene-2-norbornene, 5-methylene-2-norbornene, 5-isopropyl Reden-2-norbol , 6-chloromethyl-5-isopropylene-2-norbornene, 2,3-diisopropylidene-5-norbornene, 2-ethylidene-3-isopropylidene-5-norbornene, 2-propenyl-2,2-norbornadiene, etc. Non-conjugated polyenes.

  In the 4-methyl-1-pentene copolymer (A1) in the present invention, the units derived from the polymerizable compound are all polymerizable components contained in the 4-methyl-1-pentene copolymer (A1). 10 mol% or less may be contained with respect to the compound structural unit, and may be contained in an amount of 5 mol% or less and 3 mol% or less.

  In the present invention, the intrinsic viscosity [η] measured in 135 ° C. decalin of the 4-methyl-1-pentene copolymer (A1) is preferably 0.5 to 5.0 dL / g.

  Here, the intrinsic viscosity [η] is preferably in the range of 1.0 to 4.0 dL / g, and more preferably in the range of 1.2 to 3.5 dL / g.

  The value of the intrinsic viscosity [η] can be adjusted by the amount of hydrogen added during the polymerization when the 4-methyl-1-pentene copolymer (A1) is produced.

  The 4-methyl-1-pentene copolymer (A1) having an intrinsic viscosity [η] in the above range exhibits good fluidity during production of the resin composition and various moldings, and includes polypropylene and the like. Dispersibility in the thermoplastic resin (B) is improved, and a molded product with a beautiful appearance is obtained.

  Molecular weight distribution which is the ratio of the weight average molecular weight (Mw) and the number average molecular weight (Mn) measured by gel permeation chromatography (GPC) of the 4-methyl-1-pentene copolymer (A1) in the present invention. (Mw / Mn) is preferably 1.0 to 3.5. Here, the molecular weight distribution (Mw / Mn) is preferably in the range of 1.0 to 3.5, and more preferably in the range of 1.5 to 3.0.

  The value of the molecular weight distribution (Mw / Mn) can be adjusted depending on the type of olefin polymerization catalyst described later.

  The polymer composition containing the 4-methyl-1-pentene copolymer (A1) having a molecular weight distribution (Mw / Mn) value in the above range tends to have a relatively low molecular weight component content. . For this reason, the low molecular weight body is less bleed out, the blocking property is lowered, and it is preferable from the viewpoints of overall film properties, particularly mechanical strength and appearance.

  In the present invention, the molecular weight distribution (Mw / Mn), which is the ratio of the weight average molecular weight (Mw) and the number average molecular weight (Mn), of the 4-methyl-1-pentene copolymer (A1) is gel permeation chromatography. It is a value calculated by a standard polystyrene conversion method using (GPC).

The density of the 4-methyl-1-pentene copolymer (A1) in the present invention is preferably 825 to 860 kg / m ³ . Here, the density is preferably in the range of 830~855kg / ^{m 3,} more preferably in the range of 830~850kg / ^{m 3,} more preferably in the range of 830~845kg / ^{m 3.}

  The density value can be adjusted by selecting the type and blending amount of other α-olefins to be polymerized with 4-methyl-1-pentene. A polymer composition containing a 4-methyl-1-pentene copolymer (A1) having a density value in the above range is preferable from the viewpoints of heat resistance and lightness. The density of the 4-methyl-1-pentene copolymer (A1) is a value measured according to JIS K7112 (density gradient tube method).

  In the present invention, the melting point (Tm) of the 4-methyl-1-pentene copolymer (A1) measured by DSC is preferably 100 to 199 ° C, more preferably 110 to 180 ° C. Preferably, it is in the range of 125-158 ° C, more preferably in the range of 125-150 ° C. The melting point (Tm) value is a value that changes depending on the stereoregularity of the polymer and the amount of α-olefin polymerized together, and is controlled and adjusted to a desired composition using an olefin polymerization catalyst described later. It is possible.

  From the viewpoint of moldability, the polymer composition containing the 4-methyl-1-pentene copolymer (A1) having a melting point (Tm) in the above range is less sticky and has good handling properties. preferable.

  The 4-methyl-1-pentene copolymer (A1) in the present invention comprises 4-methyl-1-pentene, the above-mentioned specific α-olefin, and, if necessary, the polymerization in the presence of an olefin polymerization catalyst. It can be obtained by polymerizing the active compound.

Among the above-mentioned olefin polymerization catalysts, a metallocene catalyst can be mentioned as a preferred embodiment of the catalyst for producing the 4-methyl-1-pentene copolymer (A1).
Preferred metallocene catalysts include those described in International Publication No. 01/53369, International Publication No. 01/27124, Japanese Patent Application Laid-Open No. 3-193396, Japanese Patent Application Laid-Open No. 02-41303 or International Publication No. 2006/025540, International Publication No. The metallocene catalyst described in 2014/050817 etc. is mentioned.

  The content of the 4-methyl-1-pentene copolymer (A1) in the film of the present invention is preferably 5% by mass to 95% by mass, and preferably 10% by mass to 80% by mass with respect to the total mass of the surface protective film. More preferably, it is 10 mass% or less and 70 mass% or less is more preferable. When in the above range, the affinity with polypropylene (A2), which will be described later, is high, and therefore the 4-methyl-1-pentene copolymer (A1) can be finely dispersed in the system. When a film is produced using the resin composition, the 4-methyl-1-pentene copolymer (A1) is less likely to fall off, and the blocking resistance can be maintained over a long period of time. .

[Polypropylene (A2)]
The polypropylene (A2) in the present invention is a known polymer mainly composed of propylene. Examples thereof include propylene homopolymers, propylene / α-olefin copolymers of propylene and α-olefins other than propylene. (Random copolymer, block copolymer, propylene / ethylene copolymer, propylene / 1-butene copolymer, propylene / ethylene / 1-butene copolymer, or a mixture thereof). As the polypropylene, isotactic polypropylene and syndiotactic polypropylene are preferably used, and the isotactic meso pendant fraction (mmmm) or the syndiotactic meso pendant fraction (rrrr) exhibiting stereoregularity is 90% or more. Preferably, it is 92% or more, and 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. 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 compounds, aryl phosphate compounds, cyclic polyvalent metal aryl phosphate compounds, and aliphatic monocarboxylic acid alkalis Examples thereof include a metal salt or a mixture of basic aluminum, lithium, hydroxy, carbonate, hydrate, and α crystal nucleating agent such as various polymer compounds. These crystallization nucleating agents can be used alone or in combination of two or more materials.

  The MFR of the polypropylene (A2) can be measured according to JIS K7210. Specifically, it is preferably 0.5 to 25 g / 10 minutes, more preferably 1 to 15 g / 10 minutes, and more preferably 2 to 10 g / min under measurement conditions of a temperature of 230 ° C. and a load of 2.16 kg. More preferably, it is 10 minutes. When the MFR of the propylene-based polymer is in the above range, it is suitable for extrusion molding.

  The amount of ash resulting from the polymerization catalyst residue contained in the polypropylene (A2) is preferably as small as possible and is preferably 50 ppm or less in order to reduce minute foreign matters (fish eyes). More preferably, it is 40 ppm or less. By setting it to 50 ppm or less, fine foreign matters and defects are remarkably reduced, and contamination when used for electronic parts can be reduced.

  The content of polypropylene (A2) in the film of the present invention is preferably 5% by mass to 95% by mass, more preferably 20% by mass to 90% by mass, and more preferably 30% by mass with respect to the total mass of the surface protective film. More preferably, it is 90 mass% or less. When in the above range, the 4-methyl-1-pentene copolymer (A1) is finely dispersed in the system because of its high affinity with the 4-methyl-1-pentene copolymer (A1). It becomes possible.

[Other resins]
The resin composition constituting the A layer of the biaxially stretched film of the present invention includes the above-mentioned 4-methyl-1-pentene copolymer (A1) and polypropylene (A2) within the range not impairing the object of the present invention. Other resins other than) may be contained. Examples of other resins that can be added include polyolefin polymers such as polyethylene, poly 1-butene, styrene resins, and ethylene / α-olefin copolymers.

〔Additive〕
The resin composition constituting the A layer of the biaxially stretched film of the present invention contains a specific amount of 4-methyl-1-pentene copolymer (A1) and a specific amount of polypropylene (A2), Within the range not impairing the object of the present invention, for example, a weather resistance stabilizer, a heat resistance stabilizer, an antioxidant, an ultraviolet absorber, an antistatic agent, an anti-slip agent, an antiblocking agent, an antifogging agent, a nucleating agent, a lubricant, Contains various additives such as pigments, dyes, antioxidants, hydrochloric acid absorbers, inorganic or organic fillers, organic or inorganic foaming agents, crosslinking agents, crosslinking aids, adhesives, softeners, flame retardants, etc. You may do it.

  The resin composition constituting the A layer in the present invention may contain a nucleating agent that is a specific optional component in order to further improve its moldability, that is, to increase the crystallization temperature and increase the crystallization speed. Good. In this case, for example, the nucleating agent is dibenzylidene sorbitol nucleating agent, phosphate ester nucleating agent, rosin nucleating agent, benzoic acid metal salt nucleating agent, fluorinated polyethylene, 2,2-methylenebis (4,6-di- -T-butylphenyl) sodium phosphate, pimelic acid and salts thereof, 2,6-naphthalene dicarboxylic acid dicyclohexylamide, and the like, although the amount is not particularly limited, but is 0.1% relative to 100 parts by mass of the resin composition. It is preferable that there is about 1-1 mass part. There is no restriction | limiting in particular in a mixing | blending timing, It can add during superposition | polymerization, after superposition | polymerization, or a shaping | molding process.

  In the resin composition, as long as it does not impair the purpose of the present invention, a secondary antioxidant, a heat stabilizer, a weather stabilizer, an antistatic agent, a slip agent, an antifogging agent, a lubricant, Dyes, pigments, natural oils, synthetic oils, waxes, fillers, hydrochloric acid absorbents, other olefin polymers, and the like can be blended. The blending amount is not particularly limited, but is usually 0 to 50 parts by weight, preferably 0 to 30 parts by weight, more preferably 0 to 10 parts by weight, and 0 to 1 part by weight with respect to 100 parts by weight of the resin composition. Is particularly preferred.

  A known antioxidant can be used as the antioxidant. 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 these can be used.

  Examples of the lubricant include sodium, calcium and magnesium salts of saturated or unsaturated fatty acids such as lauric acid, palmitic acid, oleic acid and stearic acid, and these may be used alone or in combination of two or more. it can. Moreover, 0.1-3 mass parts is preferable normally with respect to 100 mass parts of this resin composition, and, as for the compounding quantity of this lubricant, 0.1-2 mass parts is more preferable.

  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 amide and ethylene bisstearamide are particularly preferred. These fatty acid amides are preferably blended in the range of usually 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 A layer according to the present invention comprises 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 A layer is defined as 100% by mass, Component (A1) content definition (5-95% by mass) and component (A2) content definition (5-95% by mass) are applied.

≪B layer≫
The B layer in the biaxially stretched polypropylene film of the present invention is a layer provided for imparting excellent mechanical properties to the biaxially stretched polypropylene film of the present invention. The B layer is formed from a resin composition containing polypropylene (B1). Examples of the polypropylene (B1) include the same propylene-based polymer as the polypropylene (A2) used in the A layer. The polypropylene (A2) used to form the A layer and the polypropylene (B1) used to form the B layer may be the same or different from the viewpoint of adhesiveness. preferable.

  In addition, the same heat stabilizer, antioxidant, slip agent, chlorine scavenger, antistatic agent, and the like as those added to the resin composition forming the A layer are added to the resin composition forming the B layer. It may be.

≪Biaxially stretched film≫
As a layer structure of the biaxially stretched release film of the present invention, a two-layer structure in which an A layer and a 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 C different from any of the layers (for example, a composition containing ethylene-modified isotactic polypropylene resin (random copolymer or block copolymer), atactic polypropylene, syndiotactic polypropyne, etc., olefin polymer or styrene polymer, Examples thereof include a three-layer structure in which a layer formed from a pressure-sensitive adhesive material expressing an adhesive obtained from an acrylic polymer or the like is 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 laminated film is not particularly limited, but a method of laminating by a known laminating method such as extrusion lamination or extrusion coating on a surface layer film obtained in advance by T-die molding or inflation molding. Or a method of laminating each film by dry lamination after independently molding a plurality of films, etc. From the viewpoint of productivity, coextrusion in which a plurality of components are subjected to a multilayer extruder for molding. Molding is preferred.

  Although the thickness of the film before extending | stretching which concerns on this invention is not specifically limited, Usually, it is 300 micrometers-1000 micrometers as a raw fabric sheet, 300-800 micrometers is preferable, More preferably, it is 350-500 micrometers.

  The total thickness of the biaxially stretched polypropylene film of the present invention is preferably 3 to 60 μm, more preferably 10 to 50 μm, and still 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 A layer is preferably 2 to 10%, more preferably 2 to 5% with respect to the thickness of one B layer. When the biaxially stretched polypropylene 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 at a peeling speed of 300 mm / min of the biaxially stretched polypropylene film of the present invention is preferably 7 N / 50 mm or less. More preferably, it is 1 to 6.5 N / 50 mm. The said tape peeling force can be adjusted with melting | fusing point and compounding quantity of 4-methylpentene-1 type | system | group copolymer (A).

≪Method for producing biaxially stretched film≫
About the method of mixing each component and preparing the resin composition pellet for A layer or B layer, various well-known methods, for example, a multistage polymerization method, a plast mill, a Henschel mixer, a V-blender, a ribbon blender, a tumbler , Blender, kneader ruder, etc., or after mixing, use a single screw extruder, twin screw extruder, kneader, Banbury mixer, etc. can do. By this method, high-quality resin composition pellets in which each component and additive are uniformly dispersed and mixed can be obtained.

  In the present invention, in particular, a master batch containing about 1 to 50 parts by mass of 4-methyl-1-pentene copolymer (A1) in 100 parts by mass of polypropylene (A2) is prepared in advance, and appropriately blended with it. It can also be used as the concentration of the predetermined 4-methyl-1-pentene copolymer (A1).

  The raw sheet for a biaxially stretched film of the present invention can be obtained by melt-extruding the above resin composition pellets at a cylinder temperature of usually 180 to 300 ° C.

  In order to produce a biaxially stretched film from the raw sheet, batch biaxial stretching or sequential biaxial stretching can be performed immediately after casting. In sequential biaxial stretching, the cast original fabric sheet is kept at 100 to 160 ° C., passed between rolls provided with a speed difference, stretched 4 to 5 times in the flow direction, and immediately cooled to room temperature. Next, the film is guided to a tenter and stretched 5 to 10 times in the width direction at a temperature of 160 ° C. or higher, and then relaxed and heat-set to obtain the film.

  In the biaxially stretched film of the present invention, the 4-methyl-1-pentene copolymer (A1) is present with high affinity to the polypropylene (A2). (A1) is less likely to fall off and is excellent in blocking resistance over a long period of time.

≪Usage≫
Specific applications of the biaxially stretched polypropylene film of the present invention include, for example, the following general film applications.

  Packaging film; for example, food packaging film, stretch film, wrap film, shrink film, easy peel film, aluminum vapor deposition film, PVDC coat film, and the like. Breathable film; for example, disposable diapers, sanitary products, surgical clothing, surgical gloves, surgical down, house wrap (breathable waterproof sheet), disposable warmers, household dehumidifiers, desiccants, oxygen absorbers, freshness-keeping agents, compost Sheet, simple jumper, etc. Rust prevention film; for example, automotive parts, knockdown parts, machinery / machine parts, iron / chrome products, steel pipes, wire rods, bolts / nuts, bearings, dies, tools, blades, cutting tools, building tools, etc. Examples include storage packaging and export packaging. Antifogging film; for example, a film for fruits and vegetables, a film for processed foods, etc.

Directional films: confectionery twist packaging, agricultural materials, laminate substrates, coin packaging, wire bundling materials, fruit and vegetable packaging, cardboard cut tape, detergent refill containers, rice ball packaging, pillow packaging, stick packaging, boil and retort packaging, Examples include marine food packaging and infusion bags.
Self-cleaning film; for example, road signs, general signs, signboards, window glass, road materials, side mirrors and the like.

Separators; for example, battery separators, separators for lithium ion batteries, electrolyte membranes for fuel cells, adhesive / adhesive separators, stretched films; for example, films for film capacitors, capacitor films, capacitor films for fuel cells,
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 films for electrical parts and appliances, protective films for mobile phones, protective films for personal computers, masking films, protective films for touch panels,
Film for electronic member; for example, diffusion film, reflection film, radiation resistant film, γ-ray resistant film, porous film,
Building material films; for example, building material window films, laminated glass films, bulletproof materials, bulletproof glass films, heat shield sheets, and heat shield films.

  Release film; for example, release film for flexible printed circuit board (FPC), release film for ACM board, release film for rigid flexible board, release film for advanced composite material, release film for curing carbon fiber composite material, Release film for curing glass fiber composite, Release film for curing aramid fiber composite, Release film for curing nanocomposite, Release film for curing filler filler, Release film for semiconductor sealing, Release film for polarizing plate Mold film, diffusion sheet release film, prism sheet release film, reflection sheet release film, release film cushion film, fuel cell release film, various rubber sheet release films, urethane curing release Mold film, epoxy curing release film (manufacturing process members such as metal bats and golf clubs), etc. And the like.

  Particularly preferable examples include a release film, a release liner or a separator film used for a surface protective film and an adhesive tape, and a carrier for producing a composite material.

  EXAMPLES Hereinafter, although this invention is demonstrated further more concretely based on an Example, this invention is not limited to these Examples. In the examples, each physical property was measured as follows.

〔composition〕
The contents (mol%) of 4-methyl-1-pentene and α-olefin in the polymer were measured by ¹³ C-NMR. The measurement conditions are as follows.

Measurement device: Nuclear magnetic resonance apparatus (ECP500 type, manufactured by JEOL Ltd.)
-Observation nucleus: ¹³ C (125 MHz)
・ Sequence: Single pulse proton decoupling ・ Pulse width: 4.7 μsec (45 ° pulse)
・ Repetition time: 5.5 seconds ・ Number of integration: 10,000 times or more ・ Solvent: orthodichlorobenzene / deuterated benzene (volume ratio: 80/20) mixed solvent ・ Sample concentration: 55 mg / 0.6 mL
・ Measurement temperature: 120 ℃
-Standard value of chemical shift: 27.50ppm

[Intrinsic viscosity [η]]
The intrinsic viscosity [η] of the polymer was measured at 135 ° C. in a decalin solvent using an Ubbelohde viscometer as a measuring device. Specifically, about 20 mg of the powdery copolymer was dissolved in 25 ml of decalin, and then the specific viscosity η _sp was measured in an oil bath at 135 ° C. using an Ubbelohde viscometer. After the decalin was diluted by adding 5ml to this decalin solution was measured and the specific viscosity eta _sp in the same manner as described above. This dilution operation was further repeated twice, and the value of η _sp / C when the concentration (C) was extrapolated to 0 was determined as the intrinsic viscosity [η] (unit: dl / g) (see the following formula 1) .
[Η] = lim (η _sp / C) (C → 0) Equation 1

[Weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn)]
The weight average molecular weight (Mw) of the polymer and the molecular weight distribution (Mw / Mn) represented by the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) are determined by gel permeation chromatography (GPC: Gel Permeation). It calculated by the standard polystyrene conversion method using Chromatography). The measurement conditions are as follows.
Measurement device: GPC (ALC / GPC 150-C plus type, suggestive refractometer detector integrated type, manufactured by Waters)
Column: 2 GMH6-HT (manufactured by Tosoh Corp.) and 2 GMH6-HTL (manufactured by Tosoh Corp.) are connected in series. Eluent: o-dichlorobenzene Column temperature: 140 ° C
・ Flow rate: 1.0 mL / min

[Melt flow rate (MFR)]
The melt flow rate (MFR) of the polymer was measured at 230 ° C. and a load of 2.16 kg according to ASTM D1238. The unit is g / 10 min). Only the copolymer (A1-3) obtained in Preparation Example 3 was measured under a load condition of 260 ° C. and 5.0 kg.

〔density〕
The density of the polymer was measured according to JIS K7112 (density gradient tube method). This density (kg / m ³ ) was used as an indicator of lightness.

[Melting point (Tm) and glass transition temperature (Tg)]
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 copolymer was sealed in a measurement aluminum pan and heated from room temperature to 200 ° C. at 10 ° C./min. In order to completely melt the copolymer, it was kept at 200 ° C. for 5 minutes and then cooled to −50 ° C. at 10 ° C./min. After 5 minutes at −50 ° C., the second heating was performed to 200 ° C. at 10 ° C./min. The peak temperature (° C.) at the second heating was defined as the melting point (Tm) of the copolymer, and the displacement point corresponding to the glass transition was defined as the glass transition temperature (Tg). The higher one of the melting point (Tm) and the glass transition temperature (Tg) of the polymer was used as an index of heat resistance.

[Preparation Example 1] Production of 4-methyl-1-pentene copolymer (A1-1)
A SUS autoclave with a stirring blade having a capacity of 1.5 liters sufficiently purged with nitrogen was charged with 300 ml of normal hexane at 23 ° C. (dried in a dry nitrogen atmosphere and activated alumina) and 450 ml of 4-methyl-1-pentene. . The autoclave was charged with 0.75 ml of a 1.0 mmol / ml toluene solution of triisobutylaluminum (TIBAL), 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 was 0.19 MPa (gauge pressure). Subsequently, 1 mmol of methylaluminoxane prepared in advance and diphenylmethylene (1-ethyl-3-t-butyl-cyclopentadienyl) (2,7-di-t-butyl-fluorenyl) zirconium in terms of Al were prepared. Polymerization was initiated by injecting 0.34 ml of a toluene solution containing 0.01 mmol of dichloride with nitrogen into an autoclave. During the polymerization reaction, the temperature was adjusted so that the internal temperature of the autoclave was 60 ° C. Sixty minutes after the start of polymerization, 5 ml of methanol was injected into the autoclave with nitrogen to stop the polymerization, and the autoclave was depressurized to atmospheric pressure. Acetone was poured into the reaction solution with stirring.

  The obtained powdery polymer containing the solvent was dried at 100 ° C. under reduced pressure for 12 hours. The obtained polymer was 44.0 g, the 4-methyl-1-pentene content (abbreviated as 4MP1 in Table 1) in the polymer was 84.1 mol%, and the propylene content was 15.9 mol%. The melting point (Tm) of the polymer was 132 ° C., and the intrinsic viscosity [η] was 1.5 dl / g. Table 1 shows the measurement results of various physical properties.

[Preparation Example 2] Production of 4-methyl-1-pentene copolymer (A1-2)
750 ml of 4-methyl-1-pentene was charged at 23 ° C. into a SUS autoclave with a stirring blade having a capacity of 1.5 liters sufficiently purged with nitrogen. The autoclave was charged with 0.75 ml of a 1.0 mmol / ml toluene solution of triisobutylaluminum (TIBAL), and stirring was started.

  Next, the autoclave was heated to an internal temperature of 60 ° C. and pressurized with propylene so that the total pressure was 0.17 MPa (gauge pressure). Subsequently, 1 mmol of methylaluminoxane prepared in advance, diphenylmethylene (1-ethyl-3-tert-butyl-cyclopentadienyl) (2,7-di-tert-butyl-fluorenyl) zirconium in terms of Al Polymerization was initiated by injecting 0.34 ml of a toluene solution containing 0.005 mmol of dichloride into an autoclave with nitrogen. During the polymerization reaction, the temperature was adjusted so that the internal temperature of the autoclave was 60 ° C. Sixty minutes after the start of polymerization, 5 ml of methanol was injected into the autoclave with nitrogen to stop the polymerization, and the autoclave was depressurized to atmospheric pressure. Acetone was poured into the reaction solution with stirring.

The obtained powdery polymer containing the solvent was dried at 130 ° C. under reduced pressure for 12 hours. The weight of the obtained copolymer was 35.2 g, the 4-methyl-1-pentene content in the copolymer was 91.1 mol%, and the propylene content was 8.9 mol%. The polymer had a Tm of 178.2 ° C., an intrinsic viscosity [η] of 1.6 dl / g, and a density of 832 kg / m ³ . Table 1 shows the measurement results of various physical properties.

[Preparation Example 3] Production of 4-methyl-1-pentene copolymer (A1-3) According to the methods of Comparative Example 7 and Comparative Example 9 of International Publication No. 2006/054613, 4-methyl 1-pentene, By changing the proportions of 1-decene and hydrogen, 4-methyl-1-pentene copolymer (A1-3) having physical properties shown in Table 1 was obtained. Table 1 shows the measurement results of various physical properties.

[Example 1]
As a resin composition for forming the A layer, 10 parts by mass of copolymer A1-1, polypropylene A2-1 (prime polypro (registered trademark) F113G, homopolymer of propylene, density: 910 kg / m ³ , MFR (230 ° C. ): 3 g / 10 min, 90 parts by mass (manufactured by Prime Polymer Co., Ltd.) were mixed (dry blended). The resin forming the B layer is polypropylene B2-1 (prime polypro (registered trademark) F113G, propylene homopolymer, density: 910 kg / m ³ , MFR (230 ° C.): 3 g / 10 min, ) Prime polymer) was used. The obtained mixture was set at a cylinder temperature of 240 ° C. and a die temperature of 240 ° C. using a three-type three-layer T-die sheet molding machine equipped with a T die having a lip width of 330 mm and three hopper inlets and a 30 mmφ screw. The melt-kneaded material was extruded from a T die at a thickness of 500 μm and cast, and the raw film of Example 1 was obtained. In this example, the B layer was formed using two of the three hoppers, and a two-layer two-layer film of A layer / B layer was formed.

Subsequently, using a batch type biaxial stretching machine KARO IV manufactured by Bruckner Co., a preheating temperature of 162 ° C., a preheating time of 2 minutes, a stretching temperature of 162 ° C., a stretching rate of 100% / second, a heat setting condition of 162 ° C., 30 seconds. The film obtained was stretched 5 times in the flow direction (MD) and 5 times in the width direction (TD) to obtain a biaxially stretched film having a total film thickness of 20 μm.
Regarding the obtained biaxially stretched film, it was confirmed whether or not peeling (delamination) occurred between the film layers during stretching, and the surface roughness of the obtained film and the peelability from the tape were evaluated and shown in Table 2. It was. The specific test method is as follows.

[Delami during stretching]
The peeling between the film layers after biaxial stretching was confirmed visually, and the presence or absence of delamination was confirmed.

[Surface roughness]
The surface roughness of the film was measured by the contact needle method in accordance with JIS B0601-1994, and the surface roughness was measured at a speed of 0.15 m / sec in the range of 150 mm in the TD direction. The obtained cross-sectional curve was calculated as Rz (μm) by least square straight line correction [total haze (%)]
Based on ASTM D-1003, it measured in air | atmosphere with the digital turbidity meter (NDH-20D) by Nippon Denshoku Industries Co., Ltd.

[Evaluation of peel strength]
The peel force was measured according to the pressure-sensitive adhesive sheet test method (JIS Z0237-2000). An acrylic adhesive material (trade name Nitto Tape 31B, manufactured by Nitto Denko Corporation) was used as the adhesive material. The test film and adhesive tape cut to 50 mm width x 100 mm length were left for 1 hour in an environment with a temperature of 23 ° C. and a relative humidity of 50%, and then the adhesive film was passed back and forth twice while applying pressure with an approximately 2 kg rubber roll. Affixed to the test plate.
After pasting, it is placed in a constant environment at a temperature of 23 ° C or 50 ° C and a relative humidity of 50% for one day, and then peeled off in a 180 ° direction at a speed of 300 mm / min. The peel force at the time was measured.

[Example 2]
As a resin composition for forming layer A, 30 parts by mass of copolymer A1-1, polypropylene A2-1 (prime polypro (registered trademark) F113G, homopolymer of propylene, density: 910 kg / m ³ , MFR (230 ° C. ): 3 g / 10 min, manufactured by Prime Polymer Co., Ltd.) 70 parts by mass was mixed (dry blended) to obtain a biaxially stretched film of Example 2 by the same method as Example 1. The evaluation results of the obtained biaxially stretched film are shown in Table 2.

Example 3
As a resin composition for forming the A layer, 70 parts by mass of copolymer A1-1, polypropylene A2-1 (prime polypro (registered trademark) F113G, homopolymer of propylene, density: 910 kg / m ³ , MFR (230 ° C. ): 3 g / 10 min, 30 parts by mass (manufactured by Prime Polymer Co., Ltd.), using a twin screw extruder BT-30 (screw system 30 mmφ, L / D = 46) manufactured by Plastic Engineering Laboratory Co., Ltd. A biaxially stretched film was obtained by the same method as in Example 1 except that a resin composition granulated under the conditions of a set temperature of 270 ° C., a resin extrusion rate of 60 g / min and 200 rpm was used. The evaluation results of the obtained biaxially stretched film are shown in Table 2.

Example 4
As a resin composition of the A layer, 30 parts by mass of copolymer A1-2, polypropylene A2-1 (prime polypro (registered trademark) F113G, homopolymer of propylene, density: 910 kg / m ³ , MFR (230 ° C.): A biaxially stretched film was obtained in the same manner as in Example 1 except that 3 g / 10 min and 40 parts by mass (manufactured by Prime Polymer Co., Ltd.) were mixed (dry blended). The evaluation results of the obtained biaxially stretched film are shown in Table 2.

[Comparative Example 1]
As a resin composition of the A layer, 30 parts by mass of copolymer A1-3 and polypropylene (Prime Polypro (registered trademark) F113G, density: 910 kg / m ³ , MFR (230 ° C.): 3 g / 10 min, Prime Co., Ltd. A biaxially stretched film was obtained in the same manner as in Example 1 except that 70 parts by mass of (polymer) was mixed (dry blended). The evaluation results of the obtained biaxially stretched film are shown in Table 2.

[Comparative Example 2]
A biaxially stretched film was obtained in the same manner as in Example 1 with 100 parts by mass of polypropylene (Prime Polypro (registered trademark) F107, manufactured by Prime Polymer Co., Ltd.) for both the A layer and the B layer. The evaluation results of the obtained biaxially stretched film are shown in Table 2.

From Examples 1 to 4 in Table 2, it can be seen that the biaxially stretched film of the present invention is excellent in peelability without being peeled off between layers.
When Examples 1-3 are compared with the case where the polypropylene resin (A2-1) is used for both the A layer and the B layer (Comparative Example 2), the example in which the copolymer (A-1) is blended in the A layer is used. 1 to 3, it can be seen that peeling stress with respect to the pressure-sensitive adhesive tape after biaxial stretching, that is, releasability is good. In addition, when Examples 2 and 4 and a 4-methyl-1-pentene copolymer (A1-3) having a high 4-methyl-1-pentene content and a melting point of 200 ° C. or higher are used ( In comparison with Comparative Example 1), when the 4-methyl-1-pentene copolymer (A1-1) or (A1-2) according to the present invention is used for the A layer, delamination during stretching occurs. Moreover, it turns out that the surface roughness is also low.

The film according to the present invention is extremely excellent in releasability, maintains mechanical properties comparable to those of conventional biaxially stretched films, and is lower in temperature than conventional 4-methyl-1-pentene (co) polymers. It can be obtained by molding. Thereby, it can be suitably used as a release film for optical use, building material use, automobile part use, etc., particularly as a non-silicone type release film, release liner, separator film, and surface protective film.

Claims (5)

A biaxially stretched polypropylene film in which A layer and B layer are laminated,
A layer is composed of a resin composition containing 4-methyl-1-pentene copolymer (A1) and polypropylene (A2),
The content of the 4-methyl-1-pentene copolymer (A1) is 5% by mass to 95% by mass with respect to the total mass of the A layer, and the content of the polypropylene (A2) is A layer. 5 mass% or more and 95 mass% or less with respect to the total mass of (the total of component (A1) and component (A2) is 100 mass%), and the 4-methyl-1-pentene copolymer A film in which (A1) satisfies the following requirement [1].
[1] 96 to 80 mol% of structural units derived from 4-methyl-1-pentene and structural units derived from olefins having 2 to 20 carbon atoms (excluding 4-methyl-1-pentene) The sum is 4 to 20 mol% (provided that the total of the structural units derived from 4-methyl-1-pentene and the structural units derived from olefins having 2 to 20 carbon atoms is 100 mol%). The biaxially stretched polypropylene film according to claim 1, wherein the 4-methyl-1-pentene copolymer (A1) satisfies all the following requirements [2] to [5].
[2] Intrinsic viscosity [η] measured in decalin at 135 ° C. is 0.5 to 5.0 dl / g [3] Weight average molecular weight (Mw) and number average measured by gel permeation chromatography (GPC) Molecular weight distribution (Mw / Mn), which is a ratio to molecular weight (Mn), is 1.0 to 3.5 [4] Density is 825 to 860 kg / m ³ [5] Melting point (Tm) measured by DSC Is in the range of 100 ° C. to 199 ° C.   The biaxially oriented polypropylene film according to claim 1 or 2, wherein the 4-methyl-1-pentene copolymer (A1) has a melting point (Tm) measured by DSC in a range of 100 ° C to 180 ° C.   The biaxially according to any one of claims 1 to 3, wherein the B layer is formed from a resin composition containing polypropylene (B1) which may be the same as or different from the polypropylene (A2). Stretched polypropylene film.   The layer structure is a three-layer structure of A layer / B layer / A layer or A layer / B layer / C layer (where C layer is a layer different from both A layer and B layer). The biaxially stretched film according to any one of claims 1 to 4.