JP2008260848A - Polypropylene-based resin composition and film therefrom - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polypropylene-based resin composition that has excellent blocking resistance and scratch resistance and hardly causes a resin waste deposited near the outlet of an extruder and fish eyes even when films are produced for many hours. <P>SOLUTION: The polypropylene-based resin composition is prepared by mixing a polypropylene-based resin with 0.05-0.60 wt.% of a monodispersed silica fine powder having an average particle diameter of 1.0-5.0 μm and an apparent specific gravity of 0.1-0.5 g/cm<SP>3</SP>and the number of particles with ≤1 μm observed by a scanning electron microscope of ≤20% and 0.01-0.20 wt.% of a specific phosphite. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a polypropylene resin composition and a polypropylene film comprising the same. More specifically, the present invention relates to a polypropylene resin composition which is excellent in blocking resistance of a film and hardly generates sag and fish eyes when the film is produced for a long time, and a polypropylene film made of the same.

Polypropylene films have been used mainly for food packaging applications because they are not only excellent in transparency, rigidity, film strength, and heat seal performance, but also excellent in hygiene when in contact with food. Recently, with the widespread use of convenience stores, the packaging of contents has been progressing, and improvements in film performance suitable for each application are being promoted.
For example, in the case of a snack film packaging film, aluminum vapor deposition is often performed to prevent oxidative deterioration of the contents, but the adhesive strength between the aluminum vapor deposition film and the polypropylene film decreases depending on the type and amount of additives to be blended. It is a problem to do.
Particularly problematic in reducing the vapor deposition strength is the fatty acid amide blended to improve the slipperiness and blocking resistance of the film. When a film is formed without blending these additives, the transparency and resistance of the film are reduced. The balance of blocking properties deteriorates.
Currently, improvement is being made with polypropylene resins with excellent blocking resistance, and polypropylene resins that are polymerized with high-performance catalysts such as metallocene catalysts and Ti-Mg catalysts that have few low molecular weight components are being investigated. .
However, when such a low molecular weight component polypropylene-based resin is formed for a long time with a large-scale film forming machine, a processing defect phenomenon called “Meanyi” is likely to occur, which is a problem because film productivity is lowered. .

“Mayani” is a phenomenon in which additives and PP deteriorated substances adhere to the exit portion of the die from which the film is extruded. When the amount generated is increased, the film is damaged or mixed into the film, causing fish eyes.
Patent Document 1 (Japanese Patent Application Laid-Open No. 2005-171117) describes that the adhesion of sag during film formation can be reduced by blending phosphites and benzofuranones with a polypropylene resin.
However, the benzofuranones used in the above-mentioned known techniques have a problem that they may be inferior in food hygiene and cannot be applied to many applications.
As for phosphites, Patent Document 1 (Japanese Patent Application Laid-Open No. 2002-187985) also describes that the heat stability improvement effect of polypropylene resin is high and excellent in food hygiene and vapor deposition. Polypropylene films containing phosphate esters and silica fine powder are also exemplified. However, when this composition is formed on a large film molding machine, the meander is improved, but the fine silica powder reaggregates, resulting in frequent fish eyes.
JP 2005-171117 A JP 2002-187985 A

  Accordingly, an object of the present invention is to provide a polypropylene resin composition that is excellent in blocking resistance and scratch resistance of the film and that does not easily generate mesani or fish eyes when the film is produced for a long time, and a polypropylene film comprising the same. There is to do.

  As a result of intensive studies, the present inventor has found that the present invention can solve the above problems, and has completed the present invention.

That is, the present invention has an average particle diameter of 1.0 to 5.0 μm, an apparent specific gravity of 0.1 to 0.5 g / cm ³ with respect to the polypropylene-based resin, and particles of 1 μm or less as seen with a scanning electron microscope. A monodispersed fine silica powder having a number of 20% or less, 0.05 to 0.60% by weight, and 0.01 to 0.20% by weight of a phosphite represented by the following general formula (I) The present invention relates to a characteristic polypropylene-based resin composition and a film including at least one layer composed of the composition.

(Wherein R ₁ , R ₂ , R ₄ and R ₅ are each independently a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group having 5 to 8 carbon atoms, or an alkyl group having 6 to 12 carbon atoms. An alkylcycloalkyl group, an aralkyl group having 7 to 12 carbon atoms, or a phenyl group, R ₃ represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, X is a sulfur atom or a —CHR ₆ — group (R ₆ represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or a cycloalkyl group having 5 to 8 carbon atoms), and n is 0 or 1. A is an alkylene group having 2 to 8 carbon atoms or , * —CO (R ₇ ) _m — group (wherein R ₇ represents an alkylene group having 1 to 8 carbon atoms, * represents a moiety bonded to an oxygen atom, and m is 0 or 1). Y and Z are either hydroxyl groups, 1 to 8 carbon atoms An alkoxy group or an aralkyloxy group having a carbon number of 7 to 12, the other represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.)

The present invention will be described in detail below.
The polypropylene resin of the present invention is a polymer obtained by polymerizing a monomer mainly composed of propylene, a propylene-ethylene random copolymer, a propylene-ethylene-α-olefin terpolymer, and a monomer mainly composed of propylene. A copolymer component obtained by polymerizing a polymer component obtained by polymerizing a monomer and propylene and ethylene and / or a monomer comprising an α-olefin having 4 to 12 carbon atoms is produced in multiple stages of at least two stages. Examples thereof include a polypropylene copolymer (sometimes referred to as a propylene-ethylene block copolymer). Preferred are a propylene homopolymer, a propylene-ethylene random copolymer, and a propylene-ethylene-α-olefin terpolymer. These may be used alone or in combination of two or more.
Examples of the α-olefin include α-olefins having 4 to 12 carbon atoms, such as 1-butene, 2-methyl-1-propene, 1-pentene, 2-methyl-1-butene, 3-methyl- 1-butene, 1-hexene, 2-ethyl-1-butene, 2,3-dimethyl-1-butene, 2-methyl-1-pentene, 3-methyl-1-pentene, 4-methyl-1-pentene, 3,3-dimethyl-1-butene, 1-heptene, methyl-1-hexene, dimethyl-1-pentene, ethyl-1-pentene, trimethyl-1-butene, methylethyl-1-butene, 1-octene, methyl -1-pentene, ethyl-1-hexene, dimethyl-1-hexene, propyl-1-heptene, methylethyl-1-heptene, trimethyl-1-pentene, propyl-1-pentene , Diethyl-1-butene, 1-nonene, 1-decene, 1-undecene, 1-dodecene and the like. 1-butene, 1-pentene, 1-hexene and 1-octene are preferable, and 1-butene and 1-hexene are more preferable from the viewpoints of copolymerization characteristics and economy.
The content of ethylene and / or α-olefin in the copolymer is usually 0.1 to 20% by weight, preferably 1 to 10% by weight.

  The melt flow rate (MFR) measured at 230 ° C. of the polypropylene resin used in the present invention is preferably 0.1 to 20 g / 10 minutes, more preferably 1 from the viewpoint of fluidity or film formation. ~ 15 g / 10 min.

  The molecular weight distribution of the polypropylene-based resin used in the present invention is preferably a molecular weight distribution (Aw / An) measured by GPC of 5 or less from the viewpoint of blocking resistance, vapor deposition appropriateness, and low fisheye. More preferably, it is 4 or less, and most preferably 3 or less.

  The propylene-based resin having the above molecular weight distribution is, for example, a Ti-Mg-based catalyst composed of a solid catalyst component obtained by complexing a Ti compound with a magnesium compound, etc., an organoaluminum compound and, if necessary, electron donation to the solid catalyst component And a catalyst system obtained by combining a third component such as an organic compound and a metallocene catalyst. For example, JP-A-61-218606, JP-A-61-287904, It is a catalyst system described in Kaihei 7-216017.

  Examples of the polymerization method of the polypropylene resin used in the present invention include, for example, a slurry polymerization method using an inert hydrocarbon solvent, a solvent polymerization method, a liquid phase polymerization method without a solvent, a gas phase polymerization method, or continuously. A liquid phase-gas phase polymerization method and the like can be mentioned. From the viewpoint of productivity, a gas phase polymerization method, a liquid phase-gas phase polymerization method and the like are preferable.

  In the production of the polypropylene resin used in the present invention, if necessary, drying is performed at a temperature not higher than the temperature at which the polypropylene melts in order to remove the residual polypropylene solvent or the ultra-low molecular weight oligomer by-produced during the production. May be. Examples of the drying method include the methods described in JP-A Nos. 55-75410 and 2565753.

The monodispersed silica fine powder used in the present invention has an average particle diameter of 1 to 5 μm, an apparent specific gravity of 0.1 to 0.5 g / cm ³ , and has a particle number of 1 μm or less as seen with a scanning electron microscope. It is 0.05 to 0.6% by weight of monodispersed silica fine powder that is 20% or less.

  When the blending amount of the monodispersed silica fine powder exceeds 0.6% by weight, transparency and gloss are deteriorated, and when it is less than 0.05% by weight, sufficient anti-blocking performance cannot be obtained. A preferable amount of monodispersed silica fine powder is 0.1 to 0.3% by weight.

The monodispersed silica fine powder used in the present invention needs to have an average particle diameter of 1 to 5 μm and an apparent specific gravity of 0.1 to 0.5 g / cm ³ measured with a laser counter. When the average particle diameter is less than 1 μm or when the apparent specific gravity is less than 0.1 g / cm ³ , the dispersibility and anti-blocking performance of the inorganic silica fine powder are poor, and when the particle diameter exceeds 5 μm or the apparent specific gravity is When it exceeds 0.5 g / cm ³ , the scratch resistance is inferior when the films rub against each other. From the viewpoint of dispersibility, anti-blocking performance, and scratch resistance, the inorganic silica fine powder preferably has an average particle diameter of 1.5 to 4 μm and a preferred apparent specific gravity of 0.3 to 0.4 g / cm ³ .

  The monodispersed silica fine powder needs to have 20% or less of the number of particles having a size of 1 μm or less as observed with a scanning electron microscope. When silica fine powder having a particle number of 1 μm or less exceeding 20% is used in combination with phosphites, the fine powder component causes secondary aggregation and causes fish eyes.

  As the monodispersed silica fine powder, for example, porous spherical silica represented by Mizupearl manufactured by Mizusawa Chemical Co., Ltd. can be used.

  In the present invention, specific phosphite esters are blended in an amount of 0.01 to 0.2% by weight, preferably 0.01 to 0.05% by weight. If the amount of phosphites is less than 0.01% by weight, the effect of improving the sag is not obtained, and if it exceeds 0.2% by weight, the fine silica powder is re-agglomerated during film formation to form fish eyes. , Food hygiene deteriorates.

  The phosphites used in the present invention are phosphites represented by the following general formula (I).

In the phosphites represented by the general formula (I), the substituents R ₁ , R ₂ , R ₄ and R ₅ are each independently a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or 5 carbon atoms. Represents a cycloalkyl group having 8 to 8 carbon atoms, an alkylcycloalkyl group having 6 to 12 carbon atoms, an aralkyl group having 7 to 12 carbon atoms, or a phenyl group.
Here, typical examples of the alkyl group having 1 to 8 carbon atoms include, for example, methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, sec-butyl group, A t-butyl group, a t-pentyl group, an i-octyl group, a t-octyl group, a 2-ethylhexyl group, and the like can be given. Typical examples of the cycloalkyl group having 5 to 8 carbon atoms include a 1-methylcyclopentyl group. , 1-methylcyclohexyl group, 1-methyl-4-i-propylcyclohexyl group and the like, and representative examples of the aralkyl group having 7 to 12 carbon atoms include, for example, benzyl group, α-methylbenzyl group, α, Examples include α-dimethylbenzyl group.
R ₁ , R ₂ and R ₄ are preferably an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group having 5 to 8 carbon atoms, and an alkylcycloalkyl group having 6 to 12 carbon atoms. Among these, R ₁ and R ₄ are more preferably a t-butyl group, a t-pentyl group, a t-octyl group such as a t-octyl group, a cyclohexyl group, or a 1-methylcyclohexyl group.
R ₂ is more preferably carbon such as methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, sec-butyl group, t-butyl group, t-pentyl group, etc. An alkyl group having 1 to 5 atoms, more preferably a methyl group, a t-butyl group, or a t-pentyl group.
R ₅ is preferably a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or a cycloalkyl group having 5 to 8 carbon atoms, more preferably a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, i A palkyl group having 1 to 5 carbon atoms, such as -propyl group, n-butyl group, i-butyl group, sec-butyl group, t-butyl group, t-pentyl group;
The substituent R ₃ represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and examples of the alkyl group having 1 to 8 carbon atoms include the same alkyl groups as described above. Preferably they are a hydrogen atom or a C1-C5 alkyl group, More preferably, they are a hydrogen atom or a methyl machine.
Substituent X, when n is 0, represents that two groups having a phenoxy group skeleton are directly bonded, and when n is 1, a sulfur atom or an alkyl group having 1 to 8 carbon atoms. Alternatively, it represents a methylene group in which a cycloalkyl group having 5 to 8 carbon atoms may be perverted.
Here, examples of the alkyl group having 1 to 8 carbon atoms and the cycloalkyl group having 5 to 8 carbon atoms substituted in methylene include the same alkyl groups and cycloalkyl groups as described above. As the substituent X, n is preferably 0 and two groups having a phenoxy group skeleton are directly bonded, or n is 1, and a methylene group, a methyl group, an ethyl group, n- A methylene group substituted with a propyl group, an i-propyl group, an n-butyl group, an i-butyl group, a t-butyl group, or the like.
Substituent A is an alkylene group having 2 to 8 carbon atoms or * -CO (R ₇ ) _m -group (R ₇ is an alkylene group having 1 to 8 carbon atoms, and * is a bonding site with an oxygen atom. And m is 0 or 1.)
Typical examples of the C2-8 alkyl sequence are pentamethylene group, hexamethylene group, octamethylene group, 2,2-dimethyl-1,3-propylene group, butylene group, pentamethylene group, hexamethylene group. , Octamethylene group, 2,2-dimethyl-1,3-propylene group and the like. * —CO (R ₇ ) _m — group is preferably * —CO— group in which m is 0, or * —CO (CH ₂ CH ₂ ) — group in which m is 1 and R ₇ is ethylene. It is.
One of Y and Z represents a hydroxyl group, an alkoxyl group having 1 to 8 carbon atoms or an aralkyloxy group having 7 to 12 carbon atoms, and the other represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. .
Examples of the alkyl group having 1 to 8 carbon atoms include the same alkyl groups as described above. Examples of the alkoxy group having 1 to 8 carbon atoms include, for example, an alkyl moiety similar to the above alkyl group having 1 to 8 carbon atoms. An alkoxy group which is alkyl is mentioned. Moreover, as a C7-C12 aralkyloxy group, the aralkyloxy group whose aralkyl part is the same aralkyl as the said C7-C12 aralkyl is mentioned, for example.

  In the polypropylene resin composition of the present invention, a phenolic antioxidant, a phosphorus antioxidant, an acrylate antioxidant, and a neutralizing agent can be blended within a range that does not impair the object and effect of the present invention.

Examples of the phenolic antioxidant used in the present invention include 2,6-di-t-butyl-4-methylphenol and tetrakis [methylene-3 (3 ′, 5′-di-t-butyl-4-hydroxyphenyl). Propionate] methane, octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, 3,9-bis [2- {3- (3-t-butyl-4-hydroxy-5- Methylphenyl) propionyloxy} -1,1-dimethylethyl] -2,4,8,10-tetraoxaspiro [5.5] undecane, 1,3,5-tris2 [3 (3,5-di- t-butyl-4-hydroxyphenyl) poropionyloxy] ethyl isocyanate, 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxyben ) Benzene, 1,3,5-tris (3,5-di-tert-butyl-4-hydroxybenzyl) isocyanurate, 1,3,5-tris (4-tert-butyl-3-hydroxy-2, 6-dimethylbenzyl) isocyanurate, pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], triethylene glycol-N-bis-3- (3-t- Butyl-5-methyl-4-hydroxyphenyl) propionate, 1,6-hexanediol bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], 2,2-thiobis-diethylenebis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 2,2′-methylene-bis- (4-methyl-6-tert-butyl) Ruphenol), 2,2'-methylene-bis- (4-ethyl-6-tert-butylphenol), 2,2'-methylene-bis- (4-6-di-tert-butylphenol), 2,2 ' -Ethylidene-bis- (4-6-di-t-butylphenol) (cheminox 1129), 2,2'-butylidene-bis- (4-methyl-6-t-butylphenol), 4,4'-butylidene-bis -(3-methyl-6-t-butylphenol), α-tocophenols represented by vitamin E, and the like.
Among the above phenolic antioxidants, tetrakis [methylene-3 (3 ′, 5′-di-t-butyl-4-hydroxyphenyl) propionate] methane, octadecyl-3- (3,5-di-) is preferable. t-butyl-4-hydroxyphenyl) propionate, 3,9-bis [2- {3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionyloxy} -1,1-dimethylethyl]- 2,4,8,10-tetraoxaspiro [5.5] undecane, 1,3,5-tris (3,5-di-tert-butyl-4-hydroxybenzyl) isocyanurate, triethylene glycol-N- Bis-3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate, 1,6-hexanediol bis [3- (3,5-di-t-butyl) -4-hydroxyphenyl) propionate], 2,2-thiobis-diethylenebis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], α-tocophenols represented by vitamin E It consists of at least one kind selected from.
The blending amount of the phenol-based antioxidant is preferably 0.2% by weight or less with respect to the polypropylene-based resin so that the taste odor of the contents and the coloration of the film are within a range where there is no problem.

Examples of phosphorus antioxidants include tris (nonylphenyl) phosphite, tris (2,4-di-t-butylphenyl) phosphite, distearyl pentaerythritol diphosphite, bis (2,4-di-t-). Butylphenyl) pentaerythritol diphosphite, bis (2,4-di-t-butyl-6-methylphenyl) pentaerythritol diphosphite, bis (2,6-di-t-butyl-4-methylphenyl) pentaerythritol diphosphite, bis (2,4-Dicumylphenyl) pentaerythritol diphosphite, tetrakis (2,4-di-t-butylphenyl) -4,4′-diphenylenediphosnite, 2,2′-methylenebis (4,6-di) -T-butylphenyl) 2-ethylhexyl phosphite, 2,2 ' -Ethylidenebis (4,6-di-t-butylphenyl) fluorophosphite, bis (2,4-di-t-butyl-6-methylphenyl) ethyl phosphite, 2- (2,4,6-tri -T-butylphenyl) -5-ethyl-5-butyl-1,3,2-oxaphosphorinane, 2,2 ', 2 "-nitrilo [triethyl-tris (3,3', 5,5'- Tetra-t-butyl-1,1'-biphenyl-2,2'-diyl) phosphite and the like.
The blending amount of the phosphorus-based antioxidant is preferably 0.2% by weight or less with respect to the polypropylene-based resin so that the black spec, chill roll stain, and taste odor are within a range where there is no problem.

  Examples of the neutralizing agent include calcium stearate, hydrotalcite, an alkaline earth metal oxide or hydroxide, and the like. These neutralizing agents may be used alone or in combination of at least two kinds.

Examples of the hydrotalcite include an anion exchangeable layered compound represented by the following general formula (II).
[M ²⁺ 1-XM ³⁺ X (OH) ₂ ] ^{X +} [A ^r ₁₀ x / n · mH ₂ O] ^X- formula (II)
[M ²⁺ 1-XM ³⁺ X (OH) ₂ ] ^{X +} is a basic layer, and [A ^r ₁₀ x / n · mH ₂ O] ^X- is an intermediate layer. M ²⁺ is a cation of a divalent metal such as Mg ²⁺ , Mn ²⁺ , Fe ²⁺ , Co ²⁺ , Ni ²⁺ , Cu ²⁺ , Zn ²⁺ , and M ³⁺ is Al ³⁺ , Fe ³⁺ , Cr ³⁺ , Co ^3+. , A cation of a trivalent metal such as In ³⁺ . An ⁻ is OH ⁻ , F ⁻ , Cl ⁻ , Br ⁻ , No ₃ ⁻ , Co ₃ ⁻ , So ₄ ⁻ , Fe (CN) ₆ ³⁻ , CH ₃ COO ⁻ , oxalate ion, salicinate ion, etc. n-valent anion, where n is a positive integer. X is 0 <X ≦ 0.33, and m is a positive integer. The hydrotalcite may be a natural mineral or a synthetic product, and can be used regardless of its crystal structure, crystal particle diameter, water content, surface treatment, and the like. The following hydrotalcite is preferable.
_{Mg 4.5 Al 2 (OH) 13} CO 3 · 3H 2 O
Mg _4.5 Al ₂ (OH) ₁₃ (CO ₃ ) _0.8 · O _{0.2
Mg 4 Al 2 (OH) 12} CO 3 · 3H 2 O
Mg ₅ Al ₂ (OH) ₁₄ CO ₃ .4H ₂ O
Mg ₆ Al ₂ (OH) ₁₆ CO ₃ .4H ₂ O (natural mineral)
Zn ₄ Al ₂ (OH) ₁₂ CO ₃ .mH ₂ O (m is 0 to 4)
Mg ₃ ZnAl ₂ (OH) ₁₂ CO ₃ · mH ₂ O (m is 0 to 4)

  An alkaline earth metal oxide or hydroxide is an oxide or hydroxide of a metal atom of Group II of the periodic table, and examples thereof include calcium oxide, magnesium oxide, calcium hydroxide, and magnesium hydroxide. . Preferably it is calcium hydroxide.

  The blending amount of the neutralizing agent is preferably 0.001 to 0.2% by weight with respect to the polypropylene resin. More preferably, it is 0.005-0.05 weight%. When the blending amount is less than 0.001% by weight, the catalyst residue is not sufficiently deactivated, and the processing machine may be corroded. When the blending amount exceeds 0.2% by weight, the deterioration of discoloration or the stabilizer Decomposition may occur, and the effect of the present invention may be saturated, which may not be economical.

  If necessary, other additives and other resins may be added to the resin composition used in the present invention as long as the objects and effects of the present invention are not impaired. Examples of other additives include lubricants represented by higher fatty acid amides and higher fatty acid esters, antistatic agents such as glycerin esters, sorbitan acid esters, and polyethylene glycol esters of fatty acids having 8 to 22 carbon atoms, as well as nucleation. Agents, pressure-sensitive adhesives, antifogging agents, ultraviolet absorbers and the like.

  Other resins include low-density polyethylene, high-density polyethylene, ethylene-α-olefin copolymers, olefin-based resins such as polybutene, and fluorine-based resins typified by vinylidene fluoride / tetrafluoroethylene / hexafluoropropylene copolymers. Resins may be mentioned, and these may be produced with a heterogeneous catalyst or may be produced with a homogeneous catalyst typified by a metallocene catalyst. Further, styrene copolymer rubbers obtained by hydrogenating styrene-butadiene-styrene copolymers, styrene isoprene-styrene copolymers, other elastomers, and the like are also included.

  As a manufacturing method of the polypropylene resin composition of this invention, a well-known method is mentioned so that a homogeneous composition may be obtained. For example, polypropylene resin powder and various additives are blended using a mixing device such as a Henschel mixer and then directly pelletized, or a relatively high concentration additive masterbatch is added to a high-speed machine such as a twin-screw granulator. Examples thereof include a method of blending with a polypropylene resin after pelletization using a kneading extruder, a method of melting an additive and adding it to polypropylene in a liquid state, and the like.

The polypropylene film of the present invention may be a single layer film composed of the polypropylene resin composition of the present invention, or may be a laminated film including at least one layer composed of the polypropylene resin composition of the present invention. . In the case of a laminated film, the layer made of the polypropylene resin composition is preferably formed on the outermost surface of the film.
The preferred thickness of the polypropylene film of the present invention is 10 to 250 μm, more preferably 30 to 150 μm.

Examples of the method for producing the polypropylene film of the present invention include a method for forming a film under known molding conditions using a known inflation film production apparatus, T-die film production apparatus, or the like. Among these, a production method using a T-die film production apparatus is preferable.
Examples of known processing conditions when using a T-die film manufacturing apparatus are as follows.
Temperature of molten resin extruded from die lip ... 180-300 ° C
Pruning speed of molten resin at die lip ... 10 to 1500 sec ^-1
Rotating speed of chill roll: 10 to 500 m / min
Chill roll temperature ... 10-80 ° C
Examples of the production method when the polypropylene film of the present invention is a multilayer film include commonly used coextrusion methods, extrusion lamination methods, thermal lamination methods, and dry lamination methods.
The polypropylene film of the present invention can also be produced by stretching a film or sheet obtained by molding in advance. Examples of the stretching method include a method of stretching uniaxially or biaxially by a roll stretching method, a tenter stretching method, a tubular stretching method, or the like.

The polypropylene film of the present invention can also be used as a metal-deposited polypropylene film obtained by depositing metal vapor on the film surface.
Examples of the method for producing a metal-deposited polypropylene film include a method in which the polypropylene-based film of the present invention is placed under a high vacuum, and vaporized metal vapor is introduced and deposited on the film surface. Examples of the metal to be deposited include aluminum, titanium, chromium, nickel, copper, germanium, tin, and selenium, with aluminum being preferred. The thickness of the deposited aluminum film is usually 100 to 1000 angstroms, preferably 300 to 700 angstroms.

Hereinafter, the present invention will be described with reference to examples and comparative examples.
The measured value of each item of an Example and a comparative example was measured with the following method.

(1) Molecular weight distribution (GPC)
G. P. C. (Gel permeation chromatography) was measured under the following conditions. The molecular weight distribution was evaluated by the ratio (Aw / An) of the weight average molecular weight (Aw) and the number average molecular weight (An).
Model: 150CV type (Millipore Waters);
Column: Shodex M / S 80;
Measurement temperature: 145 ° C;
Solvent: orthodichlorobenzene;
Sample concentration: 5 mg / 8 mL;
A calibration curve was prepared using standard polystyrene.

(2) Transparency (HAZE, unit:%)
It measured according to JIS K7105.

(3) Blocking resistance (unit: kg / 12cm ² )
Using a 150 mm x 30 mm film (collected so that the film forming direction and the long side direction coincide with each other), the films were overlapped, and a load of 500 g was applied to a range of 40 mm x 30 mm, and the state was maintained at 80 ° C for 24 hours. Adjustments were made. Thereafter, the sample was left in an atmosphere of 23 ° C. and 50% humidity for 30 minutes or more, peeled at a rate of 200 mm / min using a tensile tester manufactured by Toyo Seiki, and the strength required for peeling the sample was measured.

(4) Scratch resistance The silicon sheet laminated | stacked on the flat plate was installed in the measurement stand, and the film for a measurement was fixed on this silicon sheet. Thereafter, another measurement film was placed on the fixed measurement film, a load of 2 kg was applied, and the film was slid 10 times in one direction. The film Haze on the side fixed on the silicon sheet was measured before and after the treatment, and the scratch resistance was evaluated by the increase value ΔHaze.

(5) Evaluation of Meani Using a 90 mmφ extruder and a T-die film processing machine equipped with two 65 mmφ extruders, film formation was performed for 2 hours in succession to evaluate the state of adherence to the die lip. The film forming conditions and the evaluation criteria are as follows.
Molding conditions Filter: Use a sintered filter with a filtration accuracy of 60 μm.
Extruder set temperature: 280 ° C
Die set temperature: 260 ° C
Die lip gap 0.8mm
Total extrusion rate: 220 kg / hr
Film forming speed: 50 m / min Chill roll temperature: 40 ° C.
Film thickness: 70μm
Meani Evaluation Criteria: The length of the meani attached to the die was measured and evaluated along the film extrusion direction.
5 points ... The situation where there is no mains.
4 points: The average length of the length is less than 0.05 mm.
3 points: The average length of the length is 0.05 to 0.1 mm.
2 points: The average length of the length is 0.1 to 0.2 mm.
1 point: The average length of the length is 0.2 mm or more.

(6) Fish eye (FE) evaluation Film formation was performed under the same conditions as in the Meiani evaluation, and the number of defects 2 hours after the start of film formation was evaluated.
Defect evaluation uses a defect inspection apparatus (trade name DIPS, manufactured by Nireco Co., Ltd.) installed in the T-die film processing machine, and the length of the defect (length along the film flow direction) is 0.1 mm or more. The number of things was measured.

(7) Ratio of particles with a diameter of 1 μm or less contained in silica fine powder Particles with a diameter of 1 μm or less by 5,000-times observation of silica fine powder using a scanning electron microscope and image analysis of the obtained photograph The ratio of was calculated.

  Each component used in Examples and Comparative Examples is as follows.

[Phosphorous esters]
Compound name: 2,4,8,10-tetra-t-butyl-6- [3- (3-methyl-4-hydroxy-5-tbutylphenyl) propoxy] dibenzo [d, f] [1,3 2] Dioxaphosphepine Brand name Sumitomo Chemical, Sumitomo Chemical
[Phenolic antioxidant]
Product Name Irganox 1010 (Ciba Specialty Chemicals)
[Phosphorus antioxidant]
Product name Ilgafos 168 (Ciba Specialty Chemicals)
[Silica fine powder (1)]
Product name Silica manufactured by Fuji Silysia Co., Ltd. Product name Silicia 420
The average particle diameter measured by a laser diffraction particle size distribution measurement method was 3.0 μm, the apparent specific gravity was 0.21 g / cm ³ , and the number of particles of 1 μm or less observed by scanning electron microscope observation was 96%.
[Silica fine powder (2)]
Product name Mizusawa Chemical Co., Ltd. Product name Mizupearl K300
The average particle diameter measured by the laser diffraction particle size distribution measurement method was 2.7 μm, the apparent specific gravity was 0.41 g / cm ³ , and the number of particles of 1 μm or less observed by scanning electron microscope was 9%.
[Silica fine powder (3)]
Product name Made by Mizusawa Chemical Co., Ltd. Product name Shilton JC30
The average particle diameter by a laser diffraction particle size distribution measurement method was 2.9 μm, the apparent specific gravity was 0.70 g / cm ³ , and the number of particles having a particle diameter of 1 μm or less as observed with a scanning electron microscope was 0%.

[Polypropylene resin (1)]
A copolymer of propylene, ethylene and butene-1 was polymerized in the gas phase using a Ti-Mg catalyst based Ziegler-Natta type catalyst. The obtained resin powder had an ethylene content of 2.2% by weight, a butene-1 content of 4.5% by weight, and a molecular weight distribution Aw / An of 3.2.
[Polypropylene resin (2)]
A propylene / ethylene copolymer was polymerized in the gas phase using a Ti-Mg catalyst based Ziegler-Natta catalyst. The obtained resin powder had an ethylene content of 4% by weight and a molecular weight distribution Aw / An of 3.8.
[Polypropylene resin composition (1)]
To the polypropylene resin (1), 0.09% by weight of a phenolic antioxidant and 0.05% by weight of phosphites were mixed with a Henschel mixer, and then melt-extruded and pelletized.
[Polypropylene resin composition (2)]
After 0.13% by weight of a phenolic antioxidant was mixed with the polypropylene resin (1) with a Henschel mixer, it was pelletized by melt extrusion.
[Polypropylene resin composition (3)]
The polypropylene resin (1) was mixed with 0.18% by weight of a phosphite ester using a Henschel mixer, and then melt-extruded and pelletized.

[High-density polyethylene (1)]
Product name G1801 made by Keiyo Polyethylene
[High-density polyethylene (2)]
Product name G2502 manufactured by Keiyo Polyethylene

[Silica fine powder masterbatch (1)]
MB138-1B manufactured by Sumitomo Chemical Co., Ltd. (silica fine powder (1) blending amount: 2.3 wt%)
[Silica fine powder masterbatch (2)]
Silica fine powder (2) 2.3 wt% with respect to polypropylene resin (2) using a 30mmφ bi-directional granulator with different direction, cylinder setting temperature 230 ° C, extrusion rate 20kg / hr, screw rotation speed 300rpm Then, pellets containing 0.15% by weight of phenolic antioxidant and 0.5% by weight of phosphorus antioxidant were granulated.
[Silica fine powder masterbatch (3)]
Silica fine powder (3) 2.3 wt% with respect to polypropylene resin (2) using a 30mmφ bi-directional granulator with different directions, cylinder setting temperature 230 ° C, extrusion rate 20kg / hr, screw rotation speed 300rpm Then, pellets containing 0.15% by weight of phenolic antioxidant and 0.5% by weight of phosphorus antioxidant were granulated.

Example 1
Polypropylene resin composition (3) 91.5 wt%, silica fine powder masterbatch (2) 7.0 wt%, and high density polyethylene (2) 1.5 wt% were pellet blended, and the filtration accuracy was 60 μm. Using a 90mmφ extruder using a sintered metal filter and two 65mmφ extruders, it is melt kneaded at 280 ° C and introduced into a feed block type T die (die width 1250mm, lip opening 0.8mm). Then, melt extrusion was performed at a die temperature of 260 ° C.
The extruded molten film was cooled and solidified with a chill roll having a cooling water temperature of 40 ° C. rotating at 50 m / min, and an unstretched film having a thickness of 70 μm was formed for 2 hours to evaluate the occurrence state of mayani and fish eyes.
After completion of the evaluation of the scouring and fish eyes, the take-up speed of the molten film was increased to 135 m / min to obtain a film physical property evaluation film (thickness 25 μm).
Example 2
After pellet blending of 91.5% by weight of the polypropylene resin composition (2), 7.0% by weight of silica fine powder masterbatch (2) and 1.5% by weight of high-density polyethylene (1), Example 1 In the same manner, a film was obtained.
Example 3
After pellet blending 89.5% by weight of the polypropylene resin composition (1), 7.0% by weight of silica fine powder masterbatch (2) and 1.5% by weight of high-density polyethylene (1), Example 1 In the same manner, a film was obtained.

Comparative Example 1
After pellet blending 91.5 wt% of the polypropylene resin composition (2), 7.0 wt% of silica fine powder masterbatch (1) and 1.5 wt% of high density polyethylene (1), Example 1 and A film was obtained in the same manner.
Comparative Example 2
After pellet blending the polypropylene resin composition (3) 91.5% by weight, silica fine powder masterbatch (1) 7.0% by weight and high density polyethylene (2) 1.5% by weight, Example 1 and A film was obtained in the same manner.
Comparative Example 3
After pellet blending of 91.5% by weight of the polypropylene resin composition (2), 7.0% by weight of silica fine powder masterbatch (2) and 1.5% by weight of high-density polyethylene (1), Example 1 and A film was obtained in the same manner.
Comparative Example 4
After pellet blending 91.5% by weight of the polypropylene resin composition (1), 7.0% by weight of silica fine powder masterbatch (3) and 1.5% by weight of high density polyethylene, the same procedure as in Example 1 was performed. To obtain a film.

It can be seen that Examples 1 to 3 that satisfy the requirements of the present invention are polypropylene-based resin compositions that are excellent in blocking resistance and scratch resistance, and are less likely to generate scouring and fish eyes during film formation.
On the other hand, Comparative Examples 1 to 3 that do not satisfy the apparent specific gravity of the silica fine powder, the ratio of the silica fine powder of 1 μm or less, and the type of antioxidant, which are the requirements of the present invention, It can be seen that Comparative Example 4, which does not satisfy the apparent specific gravity of the silica fine powder, which is a requirement of the present invention, is inferior in the scratch resistance of the film because the fish eye reduction effect and film physical properties are insufficient.

Claims (3)

With respect to the polypropylene resin, the average particle size is 1.0 to 5.0 μm, the apparent specific gravity is 0.1 to 0.5 g / cm ³ , and the number of particles of 1 μm or less as seen by observation with a scanning electron microscope is 20% or less. And a monodispersed silica fine powder of 0.05 to 0.60 wt% and a phosphite ester represented by the following general formula (I) of 0.01 to 0.20 wt% Resin composition.

(Wherein R ₁ , R ₂ , R ₄ and R ₅ are each independently a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group having 5 to 8 carbon atoms, or an alkyl group having 6 to 12 carbon atoms. An alkylcycloalkyl group, an aralkyl group having 7 to 12 carbon atoms, or a phenyl group, R ₃ represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, X is a sulfur atom or a —CHR ₆ — group (R ₆ represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or a cycloalkyl group having 5 to 8 carbon atoms), and n is 0 or 1. A is an alkylene group having 2 to 8 carbon atoms or , * —CO (R ₇ ) _m — group (wherein R ₇ represents an alkylene group having 1 to 8 carbon atoms, * represents a moiety bonded to an oxygen atom, and m is 0 or 1). Y and Z are either hydroxyl groups, 1 to 8 carbon atoms An alkoxy group or an aralkyloxy group having a carbon number of 7 to 12, the other represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.)   The polypropylene resin composition according to claim 1, wherein the polypropylene resin has a molecular weight distribution (Aw / An) of 5 or less.   A polypropylene film comprising at least one layer mainly composed of the polypropylene resin composition according to claim 1.