JP2018141122A - Biaxially oriented polypropylene film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a biaxially oriented laminated polypropylene film having higher heat resistance and rigidity.SOLUTION: There is provided a biaxially oriented polypropylene film, where a polypropylene resin constituting a film satisfies the following 1) to 4) conditions and a lower limit of a plane orientation coefficient of the film is 0.0125. 1) A lower limit of a mesopentad fraction is 96%. 2) An upper limit of a copolymerizable monomer amount other than propylene is 0.1 mol%. 3) Mass average molecular weight (Mw)/number average molecular weight (Mn) is 3.0 or more and 5.4 or less. 4) A melt flow rate (MFR) measured at 230°C and 2.16 kgf is 6.2 g/10 min or more and 9.0 g/10 min or less.SELECTED DRAWING: None

Description

  The present invention relates to a biaxially stretched laminated polypropylene film. Specifically, the present invention relates to a biaxially stretched polypropylene film having excellent heat resistance and mechanical properties.

  Conventionally, stretched polypropylene films have been widely used in a wide range of applications such as packaging of food and various products, electrical insulation, and surface protection films. However, the conventional polypropylene film has a shrinkage rate of several tens of percent at 150 ° C., and has low heat resistance and low rigidity as compared with a polyethylene terephthalate (PET) film or the like.

  Various techniques for improving the physical properties of polypropylene films have been proposed. For example, rigidity and processability can be achieved by forming a film using polypropylene containing almost the same amount of high molecular weight component and low molecular weight component (or low low molecular weight component), wide molecular weight distribution, and low decalin soluble content. A technique of balancing is known (Patent Document 1). However, with this technique, heat resistance at a high temperature exceeding 150 ° C. has not been sufficient yet, and a polypropylene film having high heat resistance, excellent impact resistance and transparency has not been known. .

  As a result of intensive studies based on the above-described conventional technology, the applicant of the present application is to provide a stretched polypropylene film having high rigidity and high heat resistance by using a polypropylene polymer having a mesopentad fraction of 96% or more. Successful (Patent Document 2). However, this film has room for improvement in heat resistance.

Special table 2008-540815 WO2015 / 012324 pamphlet

  In view of the above circumstances, the present invention has been aimed at providing a biaxially stretched laminated polypropylene film having higher heat resistance and rigidity.

The present invention that has solved the above problems is characterized in that the polypropylene resin constituting the film satisfies the following conditions 1) to 4), and the lower limit of the plane orientation coefficient of the film is 0.0125. It is a biaxially oriented polypropylene film.
1) The lower limit of the mesopentad fraction is 96%.
2) The upper limit of the amount of copolymerization monomers other than propylene is 0.1 mol%.
3) The mass average molecular weight (Mw) / number average molecular weight (Mn) is 3.0 or more and 5.4 or less. 4) The melt flow rate (MFR) measured at 230 ° C. and 2.16 kgf is 6.2 g / 10 min or more and 9.0 g / 10 min or less.

In addition, the second aspect of the present invention capable of solving the above-mentioned problems is that the polypropylene resin is a main component on at least one surface of the base material layer (A) and the base material layer (A) whose main component is a polypropylene resin. The polypropylene layer constituting the base material layer (A) satisfies the conditions 1) to 4) below, and the lower limit of the plane orientation coefficient of the film is 0.0125. A biaxially oriented polypropylene film characterized by that.
1) The lower limit of the mesopentad fraction is 96%.
2) The upper limit of the amount of copolymerization monomers other than propylene is 0.1 mol%.
3) The mass average molecular weight (Mw) / number average molecular weight (Mn) is 3.0 or more and 5.4 or less. 4) The melt flow rate (MFR) measured at 230 ° C. and 2.16 kgf is 6.2 g / 10 min or more and 9.0 g / 10 min or less.

  In this case, it is preferable that the thermal shrinkage rate at 150 ° C. in the vertical and horizontal directions of the film is 8% or less.

  In this case, it is preferable that the tensile modulus in the longitudinal direction of the film is 2.0 GPa or more and the tensile modulus in the transverse direction of the film is 4.5 GPa or more.

  In this case, the haze value of the film is preferably 5% or less.

The biaxially oriented polypropylene film of the present invention has a smaller molecular weight distribution and less entanglement of molecular chains, so the orientation is stronger, it has higher thermal dimensional stability and lateral rigidity, and less heat loss wrinkles. Since it is difficult to break, it has excellent film processability.

The biaxially oriented polypropylene film of the first invention is characterized in that the polypropylene resin constituting the film satisfies the following conditions 1) to 4), and the lower limit of the plane orientation coefficient of the film is 0.0125. And
1) The lower limit of the mesopentad fraction is 96%.
2) The upper limit of the amount of copolymerization monomers other than propylene is 0.1 mol%.
3) The mass average molecular weight (Mw) / number average molecular weight (Mn) is 3.0 or more and 5.4 or less. 4) The melt flow rate (MFR) measured at 230 ° C. and 2.16 kgf is 6.2 g / 10 min or more and 9.0 g / 10 min or less.
The biaxially oriented polypropylene film of the second invention is a surface mainly comprising a polypropylene resin on the surface of at least one of a base material layer (A) and a base material layer (A) mainly comprising a polypropylene resin. The polypropylene resin having the layer (B) and constituting the base material layer (A) satisfies the following conditions 1) to 4), and the lower limit of the plane orientation coefficient of the film is 0.0125. Features.
1) The lower limit of the mesopentad fraction is 96%.
2) The upper limit of the amount of copolymerization monomers other than propylene is 0.1 mol%.
3) The mass average molecular weight (Mw) / number average molecular weight (Mn) is 3.0 or more and 5.4 or less. 4) The melt flow rate (MFR) measured at 230 ° C. and 2.16 kgf is 6.2 g / 10 min or more and 9.0 g / 10 min or less.
Further details will be described below.

(1) As the polypropylene resin used in the first invention, a polypropylene resin obtained by copolymerizing ethylene and / or an α-olefin having 4 or more carbon atoms at 0.5 mol% or less can also be used. Such a copolymerized polypropylene resin is also included in the polypropylene resin of the present invention (hereinafter referred to as polypropylene resin). The copolymerization component is preferably 0.3 mol% or less, more preferably 0.1 mol% or less, and most preferably a complete homopolypropylene resin containing no copolymerization component.
When ethylene and / or an α-olefin having 4 or more carbon atoms is copolymerized in excess of 0.5 mol%, the crystallinity and rigidity may be excessively lowered, and the thermal shrinkage at high temperatures may be increased. You may blend and use such resin.

  The mesopentad fraction ([mmmm]%) measured by 13 C-NMR, which is an index of stereoregularity of the polypropylene resin, is preferably 96 to 99.5%. More preferably, it is 97% or more, and more preferably 98% or more. When the mesopentad ratio of the polypropylene of the base material layer (A) is small, the elastic modulus is low and the heat resistance may be insufficient. 99.5% is a realistic upper limit.

Further, Mw / Mn, which is an index of molecular weight distribution, is preferably 3.0 to 5.4 in the case of polypropylene resin. More preferably, it is 3.0-5.0, More preferably, it is 3.2-4.5, Most preferably, it is 3.3-4.0.
When the Mw / Mn of the entire polypropylene resin constituting the biaxially oriented polypropylene film of the present invention exceeds 5.4, if the Mw / Mn is too large, the high molecular weight component increases and the thermal shrinkage rate may increase. Or the tensile modulus (Young's modulus) in the width direction (TD) tends to be small. When the molecular weight component is present, the high molecular weight component promotes the crystallization of the low molecular weight component, but the entanglement between the molecules becomes strong, and the thermal shrinkage tends to increase even if the crystallinity is high.
When the Mw / Mn of the entire polypropylene resin constituting the biaxially oriented polypropylene film of the present invention is less than 3.0, film formation becomes difficult.
Mw means mass average molecular weight, and Mn means number average molecular weight.

  The mass average molecular weight (Mw) of the polypropylene resin is preferably 180,000 to 500,000. The lower limit of Mw is more preferably 190,000, still more preferably 200,000, and the upper limit of more preferable Mw is 320,000, more preferably 300,000, particularly preferably 250,000.

  The number average molecular weight (Mn) of the polypropylene resin is preferably 20,000 to 200,000. The lower limit of Mn is more preferably 30,000, more preferably 40,000, particularly preferably 50,000, and the upper limit of Mn is more preferably 80,000, still more preferably 70,000, particularly preferably 60,000. is there.

When the gel permeation chromatography (GPC) integration curve of the entire polypropylene resin constituting the biaxially oriented polypropylene film of the first invention is measured, the lower limit of the amount of the component having a molecular weight of 100,000 or less is preferably 35% by mass. More preferably, it is 38 mass%, More preferably, it is 40 mass%, Especially preferably, it is 41 mass%, Most preferably, it is 42 mass%.
On the other hand, the upper limit of the amount of the component having a molecular weight of 100,000 or less in the GPC integration curve is preferably 65% by mass, more preferably 60% by mass, still more preferably 58% by mass, and particularly preferably 56% by mass. And most preferably 55% by weight. Within the above range, stretching can be facilitated, thickness spots can be reduced, stretching temperature and heat setting temperature can be easily increased, and the heat shrinkage rate can be further reduced.

The melt flow rate (MFR; 230 ° C., 2.16 kgf) of the polypropylene resin at this time is preferably 6.2 g / 10 min to 10.0 g / 10 min.
The lower limit of the MFR of the polypropylene resin is more preferably 6.5 g / 10 minutes, further preferably 7 g / 10 minutes, and particularly preferably 7.5 g / 10 minutes. The upper limit of the MFR of the polypropylene resin is more preferably 9 g / 10 minutes, further preferably 8.5 g / 10 minutes, and particularly preferably 8.2 g / 10 minutes.
When the melt flow rate (MFR; 230 ° C., 2.16 kgf) is 6.2 g / 10 min or more, the thermal contraction rate at a high temperature can be further reduced. Furthermore, since the degree of orientation of the film generated by stretching becomes strong, the rigidity of the film, particularly the tensile modulus (Young's modulus) in the width (TD) direction is increased. Further, when the melt flow rate (MFR; 230 ° C., 2.16 kgf) is 9.0 g / 10 min or less, it is easy to form a film without breaking.
The molecular weight distribution of polypropylene resin is such that components with different molecular weights are polymerized in a series of plants in multiple stages, components with different molecular weights are blended offline using a kneader, or catalysts with different performances are blended. It is possible to adjust by using a catalyst which can be polymerized or a catalyst capable of realizing a desired molecular weight distribution.

The polypropylene resin used in the present invention is obtained by polymerizing propylene as a raw material using a known catalyst such as a Ziegler-Natta catalyst or a metallocene catalyst. Among these, in order to eliminate the heterogeneous bond, it is preferable to use a Ziegler-Natta catalyst and a catalyst capable of polymerization with high stereoregularity.
As a polymerization method of propylene, a known method may be employed. For example, a method of polymerizing in an inert solvent such as hexane, heptane, toluene, xylene, a method of polymerizing in a liquid monomer, a catalyst for a gas monomer And a method of polymerizing in a gas phase state, or a method of polymerizing these in combination.

  The polypropylene resin may contain additives and other resins. Examples of the additive include an antioxidant, an ultraviolet absorber, a nucleating agent, an adhesive, an antifogging agent, a flame retardant, and an inorganic or organic filler. Examples of other resins include polypropylene resins other than the polypropylene resin used in the present invention, random copolymers that are copolymers of propylene and ethylene and / or α-olefins having 4 or more carbon atoms, and various elastomers. These are sequentially polymerized using a multistage reactor, blended with a polypropylene resin and a Henschel mixer, or master pellets prepared in advance using a melt kneader are diluted with polypropylene to a predetermined concentration. Alternatively, the whole amount may be melt kneaded in advance.

(2) As the polypropylene resin used in the base material layer (A) of the second invention, a polypropylene resin obtained by copolymerizing ethylene and / or an α-olefin having 4 or more carbon atoms at 0.5 mol% or less can also be used. . Such a copolymerized polypropylene resin is also included in the polypropylene resin of the present invention (hereinafter referred to as polypropylene resin). The copolymerization component is preferably 0.3 mol% or less, more preferably 0.1 mol% or less, and most preferably a complete homopolypropylene resin containing no copolymerization component.
When ethylene and / or an α-olefin having 4 or more carbon atoms is copolymerized in excess of 0.5 mol%, the crystallinity and rigidity may be excessively lowered, and the thermal shrinkage at high temperatures may be increased. You may blend and use such resin.

  The mesopentad fraction ([mmmm]%) measured by 13 C-NMR, which is an index of stereoregularity of the polypropylene resin, is preferably 96 to 99.5%. More preferably, it is 97% or more, and more preferably 98% or more. When the mesopentad ratio of the polypropylene of the base material layer (A) is small, the elastic modulus is low and the heat resistance may be insufficient. 99.5% is a realistic upper limit.

Further, Mw / Mn, which is an index of molecular weight distribution, is preferably 3.0 to 5.4 in the case of polypropylene resin. More preferably, it is 3.0-5.0, More preferably, it is 3.2-4.5, Most preferably, it is 3.3-4.0.
When Mw / Mn of the entire polypropylene resin constituting the base material layer (A) exceeds 5.4, if Mw / Mn is too large, the high molecular weight component is increased, and the thermal shrinkage rate may be increased. The tensile modulus (Young's modulus) in the width direction (TD) tends to be small.
When the molecular weight component is present, the high molecular weight component promotes the crystallization of the low molecular weight component, but the entanglement between the molecules becomes strong, and the thermal shrinkage tends to increase even if the crystallinity is high.
When the Mw / Mn of the entire polypropylene resin constituting the biaxially oriented polypropylene film of the present invention is less than 3.0, film formation becomes difficult. Mw means mass average molecular weight, and Mn means number average molecular weight.

  The mass average molecular weight (Mw) of the polypropylene resin is preferably 180,000 to 500,000. The lower limit of Mw is more preferably 190,000, still more preferably 200,000, and the upper limit of more preferable Mw is 320,000, more preferably 300,000, particularly preferably 250,000.

  The number average molecular weight (Mn) of the polypropylene resin is preferably 20,000 to 200,000. The lower limit of Mn is more preferably 30,000, more preferably 40,000, particularly preferably 50,000, and the upper limit of Mn is more preferably 80,000, still more preferably 70,000, particularly preferably 60,000. is there.

When the gel permeation chromatography (GPC) integration curve of the entire polypropylene resin constituting the base material layer (A) is measured, the lower limit of the amount of the component having a molecular weight of 100,000 or less is preferably 35% by mass, more preferably It is 38% by mass, more preferably 40% by mass, particularly preferably 41% by mass, and most preferably 42% by mass.
On the other hand, the upper limit of the amount of the component having a molecular weight of 100,000 or less in the GPC integration curve is preferably 65% by mass, more preferably 60% by mass, still more preferably 58% by mass, and particularly preferably 56% by mass. And most preferably 55% by weight. Within the above range, stretching can be facilitated, thickness spots can be reduced, stretching temperature and heat setting temperature can be easily increased, and the heat shrinkage rate can be further reduced.

The melt flow rate (MFR; 230 ° C., 2.16 kgf) of the polypropylene resin at this time is preferably 6.2 g / 10 min to 10.0 g / 10 min.
The lower limit of the MFR of the polypropylene resin is more preferably 6.5 g / 10 minutes, further preferably 7 g / 10 minutes, and particularly preferably 7.5 g / 10 minutes. The upper limit of the MFR of the polypropylene resin is more preferably 9 g / 10 minutes, further preferably 8.5 g / 10 minutes, and particularly preferably 8.2 g / 10 minutes.
When the melt flow rate (MFR; 230 ° C., 2.16 kgf) is 6.2 g / 10 min or more, the thermal contraction rate at a high temperature can be further reduced. Furthermore, since the degree of orientation of the film generated by stretching becomes strong, the rigidity of the film, particularly the tensile modulus (Young's modulus) in the width (TD) direction is increased. Further, when the melt flow rate (MFR; 230 ° C., 2.16 kgf) is 9.0 g / 10 min or less, it is easy to form a film without breaking.
The molecular weight distribution of polypropylene resin is such that components with different molecular weights are polymerized in a series of plants in multiple stages, components with different molecular weights are blended offline in a kneader, or catalysts with different performances are blended for polymerization. Or by using a catalyst capable of realizing a desired molecular weight distribution.

The polypropylene resin used in the base material layer (A) can be obtained by polymerizing propylene as a raw material using a known catalyst such as a Ziegler-Natta catalyst or a metallocene catalyst. Among these, in order to eliminate the heterogeneous bond, it is preferable to use a Ziegler-Natta catalyst and a catalyst capable of polymerization with high stereoregularity.
As a polymerization method of propylene, a known method may be employed. For example, a method of polymerizing in an inert solvent such as hexane, heptane, toluene, xylene, a method of polymerizing in a liquid monomer, a catalyst for a gas monomer And a method of polymerizing in a gas phase state, or a method of polymerizing these in combination.

  The polypropylene resin may contain additives and other resins. Examples of the additive include an antioxidant, an ultraviolet absorber, a nucleating agent, an adhesive, an antifogging agent, a flame retardant, and an inorganic or organic filler. Examples of other resins include polypropylene resins other than the polypropylene resin used in the present invention, random copolymers that are copolymers of propylene and ethylene and / or α-olefins having 4 or more carbon atoms, and various elastomers. These are sequentially polymerized using a multistage reactor, blended with a polypropylene resin and a Henschel mixer, or master pellets prepared in advance using a melt kneader are diluted with polypropylene to a predetermined concentration. Alternatively, the whole amount may be melt kneaded in advance.

(3) The surface roughness of the surface layer (B) of the second invention is preferably 0.027 μm or more and 0.40 μm or less. If it is less than 0.027 μm, the adhesion to the printing ink and the adhesive used for laminating with other member films are not sufficient, and if it exceeds 0.40 μm, there are problems of color developability and color fading. Arise.
In order for the surface roughness of the surface layer (B) to be 0.027 μm or more and 0.40 μm or less, the melt flow rate (MFR) as the polypropylene resin composition forming the surface layer (B) is It is preferable to use a mixture of two or more different polypropylene resins. In this case, the MFR difference is preferably 3 g / 10 min or more, and more preferably 3.5 g / 10 min or more.
By using such a mixture, the surface roughness of the surface layer (B) is estimated to be 0.027 μm or more due to the difference in crystallization speed.
As the polypropylene resin having a larger MFR, polypropylene obtained by copolymerizing ethylene and / or an α-olefin having 4 or more carbon atoms can also be used. Examples of the α-olefin having 4 or more carbon atoms include 1-butene, 1-hexene, 4-methyl 1-pentene, 1-octene and the like.
Moreover, as a polypropylene resin with a smaller MFR, polypropylene obtained by copolymerizing ethylene and / or an α-olefin having 4 or more carbon atoms can also be used. Examples of the α-olefin having 4 or more carbon atoms include 1-butene, 1-hexene, 4-methyl 1-pentene, 1-octene and the like.
Moreover, you may use the maleic acid etc. which have polarity as another copolymerization component.
The total amount of ethylene, α-olefin having 4 or more carbon atoms, and other copolymerization components is preferably 8.0 mol% or less. When the copolymerization exceeds 8.0 mol%, the film may be whitened to have a poor appearance, or may become sticky and film formation may be difficult.
These resins may be used in a blend of two or more. When blending, individual resins may be copolymerized in excess of 8.0 mol%, but the blend is preferably monomer units and monomers other than propylene at 8.0 mol% or less. .

  The polypropylene resin composition of the surface layer (B) preferably has an MFR of 1.0 g / 10 min to 8 g / 10 min. The lower limit of the MFR of the polypropylene resin composition of the surface layer (B) is more preferably 2 g / 10 minutes, and further preferably 3 g / 10 minutes. The upper limit of the MFR of the polypropylene resin composition of the surface layer (B) is more preferably 7 g / 10 minutes, and further preferably 6.0 g / 10 minutes. Within this range, the film-forming property is good and the heat shrinkage rate at high temperatures can be kept small. When the MFR of the polypropylene resin composition of the surface layer (B) is smaller than 1.0 g / 10 min, the base layer (A) and the surface layer (B) Since the viscosity difference becomes large, unevenness (raw fabric unevenness) is likely to occur during film formation. If the MFR of the polypropylene resin composition of the surface layer (B) exceeds 8 g / 10 minutes, the adhesion to the cooling roll will be poor, air will be involved, the smoothness will be poor, and there will be many drawbacks starting from it. There is a fear.

The polypropylene resin used in the surface layer (B) is obtained by polymerizing propylene as a raw material using a known catalyst such as a Ziegler-Natta catalyst or a metallocene catalyst. Among these, in order to eliminate the heterogeneous bond, it is preferable to use a Ziegler-Natta catalyst and a catalyst capable of polymerization with high stereoregularity.
As a polymerization method of propylene, a known method may be employed. For example, a method of polymerizing in an inert solvent such as hexane, heptane, toluene, xylene, a method of polymerizing in a liquid monomer, a catalyst for a gas monomer And a method of polymerizing in a gas phase state, or a method of polymerizing these in combination.

  The surface layer (B) may contain additives and other resins. Examples of the additive include an antioxidant, an ultraviolet absorber, a nucleating agent, an adhesive, an antifogging agent, a flame retardant, and an inorganic or organic filler. Examples of other resins include polypropylene resins other than the polypropylene resin used in the present invention, random copolymers that are copolymers of propylene and ethylene and / or α-olefins having 4 or more carbon atoms, and various elastomers. These are sequentially polymerized using a multistage reactor, blended with a polypropylene resin and a Henschel mixer, or master pellets prepared in advance using a melt kneader are diluted with polypropylene to a predetermined concentration. Alternatively, the whole amount may be melt kneaded in advance.

It is preferable that the surface layer (B) has a surface wetting tension of 38 mN / m or more.
When the wetting tension is 38 mN / m or more, the adhesion to the printing ink and the adhesive is improved.
The wetting tension is more preferably 16 LogΩ or more. In order to increase the wetting tension to 38 mN / m or more, it is usual to use additives such as antistatic agents and surfactants. However, since it has the effect of reducing the surface resistivity, corona treatment, flame treatment And the like, and the like.
For example, the corona treatment is preferably performed in the air using a preheating roll and a treatment roll.

The center plane peak height SR) + center plane valley depth SRv of the surface layer (B) of the biaxially oriented polypropylene film of the present invention is preferably 1.0 μm or more and 2.0 μm or less.
Here, the surface roughness of the surface of the surface layer (B), the center plane peak height SRp, and the center plane valley depth SRv are measured using a three-dimensional roughness meter at a stylus pressure of 20 mg in the X direction. Measured with 99 mm recording lines with a feed pitch of 2 μm in the Y direction, a magnification of 20000 times in the height direction, and a cutoff of 80 μm, and is obtained according to the definition of arithmetic mean roughness described in JISB0601 (1994) .

The center plane peak height SRp + center plane valley depth SRv of the surface layer (B) is an index of the state of the large unevenness formed by the lubricant, and in the state of the roll film, the base layer (A) and This is related to the slipperiness at the time of contact.
When the center surface peak height SRp + center surface valley depth SRv of the surface layer (B) is 1.0 μm or more, the unwinding property from the roll film is improved, and when it is 2.0 μm or less, the transparency is maintained. Is done.
The center plane peak height SRp + center plane valley depth SRv of the surface layer (B) is preferably 1.0 μm to 1.1 μm or more, more preferably 1.2 μm or more, and particularly preferably 1.3 μm or more.

In order to set the center surface peak height SRp + center surface valley depth SRv of the surface layer (B) to 1.0 μm or more and 2.0 μm or less, an antiblocking agent is added to the polypropylene resin composition forming the surface layer (B). It is a suitable method to mix.
As an anti-blocking agent, it can be used by appropriately selecting from inorganic anti-blocking agents such as silica, calcium carbonate, kaolin and zeolite, and organic anti-blocking agents such as acrylic, polymethacrylic and polystyrene. can do. Among these, it is particularly preferable to use silica.
The average particle diameter of the antiblocking agent is preferably 1.0 to 2.0 μm, more preferably 1.0 to 1.5 μm.
It is preferable that the anti-blocking agent has a mass of 3000 ppm in the polypropylene resin composition. The measurement method of the average particle diameter here is a method in which a photograph is taken with a scanning electron microscope, the ferret diameter in the horizontal direction is measured using an image analyzer, and the average value is displayed.

(4) Biaxially oriented polypropylene film The total thickness of the biaxially oriented polypropylene film of the present invention is preferably 9 to 200 m, more preferably 10 to 150 μm, further preferably 12 to 100 μm, and particularly preferably 12 to 80 μm.

  As a ratio of the thickness of the surface layer (B) and the base material layer (A) in the biaxially oriented polypropylene film of the second invention, the total surface layer (B) / total base material layer (A) is 0.01 to 0. 0.5, more preferably 0.03 to 0.4, and even more preferably 0.05 to 0.3. When the total surface layer (B) / total base material layer (A) exceeds 0.5, the shrinkage rate tends to increase. Moreover, it is preferable that the thickness of all the base material layers (A) with respect to the thickness of the whole film is 50 to 99%, More preferably, it is 60 to 97%, Especially preferably, it is 70 to 95%. The remainder becomes the surface layer (B) or the surface layer (B) and other layers (for example, C layer). The substantial thickness of the entire surface layer (B) is preferably 0.5 to 4 μm, more preferably 1 to 3.5 μm, and still more preferably 1.5 to 3 μm.

As a ratio of the thickness of the surface layer (B) and the base material layer (A) in the biaxially oriented polypropylene film of the second invention, the total surface layer (B) / total base material layer (A) is 0.01 to 0. 0.5, more preferably 0.03 to 0.4, and even more preferably 0.05 to 0.3. When the total surface layer (B) / total base material layer (A) exceeds 0.5, the shrinkage rate tends to increase. Moreover, it is preferable that the thickness of all the base material layers (A) with respect to the thickness of the whole film is 50 to 99%, More preferably, it is 60 to 97%, Especially preferably, it is 70 to 95%. The remainder becomes the surface layer (B) or the surface layer (B) and other layers (for example, C layer).
The substantial thickness of the entire surface layer (B) is preferably 0.5 to 4 μm, more preferably 1 to 3.5 μm, and still more preferably 1.5 to 3 μm.
The biaxially oriented polypropylene film film of the second invention may be a two-layer film having a base layer (A) and a surface layer (B) one by one, but may have a structure of three or more layers. . A two-layer structure of base material layer (A) / surface layer (B) is preferable. Also, a three-layer structure of surface layer (B) / A layer / surface layer (B), base material layer (A) / intermediate layer (C) / surface layer (B) or a multilayer structure of more than that. Good.
In addition, when there are a plurality of substrate layers (A) and surface layers (B), the compositions may be different as long as each layer satisfies the characteristics.

(5) Film properties The biaxially oriented biaxially oriented polypropylene film of the present invention preferably has a heat shrinkage rate of 150% at 150 ° C in the machine direction and the transverse direction, more preferably 7% or less, It is particularly preferably 8% or less. When the heat shrinkage rate is 8% or less, heat loss wrinkles during processing can be reduced.

  In the biaxially oriented polypropylene film of the present invention, the thermal shrinkage in the longitudinal direction at 150 ° C. is preferably 0.2 to 8%, more preferably 0.3 to 7%. If the heat shrinkage rate is in the above range, it can be said that the film has excellent heat resistance, and can be used in applications that may be exposed to high temperatures. If the thermal shrinkage at 150 ° C. is up to about 1.5%, for example, it is possible to increase the low molecular weight component, adjust the stretching conditions and the heat setting conditions, but in order to lower it below, anneal offline. It is preferable to perform the treatment.

  In the biaxially oriented polypropylene film of the present invention, the thermal contraction rate in the transverse direction at 150 ° C. is preferably 0.2 to 8%, more preferably 0.3 to 7%, and 0.4 to 6%. Is more preferable, and 0.5 to 5% is particularly preferable. If the heat shrinkage ratio is in the above range, it can be said that the film is particularly excellent in heat resistance and can be used in applications that may be exposed to high temperatures. If the thermal shrinkage at 150 ° C. is up to about 1.5%, for example, it is possible to increase the low molecular weight component, adjust the stretching conditions and the heat setting conditions, but in order to lower it below, anneal offline. It is preferable to perform the treatment.

  The tensile modulus in the machine direction of the biaxially oriented polypropylene film of the present invention is preferably 1.8 to 4 GPa, more preferably 2.1 to 3.7 GPa, and 2.2 to 3.5 GPa. More preferably, it is preferably 2.3 to 3.4 GPa. The measuring method will be described later.

  The tensile modulus in the transverse direction of the biaxially oriented polypropylene film of the present invention is preferably 4.5 to 8 GPa, more preferably 4.6 to 7.5 GPa, and 4.7 to 7 GPa. Is more preferable, and 4.8 to 6.5 GPa is particularly preferable. If the tensile modulus in the transverse direction is in the above range, it is possible to form a film that is difficult to break.

  The difficulty of folding the biaxially oriented polypropylene film of the present invention was evaluated by a ring crush measurement value detected by a load cell by holding the film in a ring shape and compressing the film. The measuring method will be described later.

  The haze of the biaxially oriented polypropylene film of the present invention is preferably 5% or less, more preferably 0.2 to 5%, further preferably 0.3 to 4.5%, and particularly preferably 0.4 to 4%. If it is within the above range, it may be easy to use in applications requiring transparency. For example, when the stretching temperature and heat setting temperature are too high, the haze tends to be worse when the cooling roll (CR) temperature is high and the stretching speed of the stretched raw sheet is slow, or when there are too many low molecular weight components. By doing so, it can be within the above range. A method for measuring haze will be described later.

The lower limit of the impact resistance (23 ° C.) of the stretched polypropylene film of the present invention is preferably 0.6 J, more preferably 0.7 J. Within the above range, the film has sufficient toughness and does not break during handling.
The upper limit of the impact resistance is preferably 3J, more preferably 2.5J, even more preferably 2.2J, and particularly preferably 2J from the practical viewpoint. For example, impact resistance tends to decrease when the total molecular weight is low when there are many low molecular weight components, when the total molecular weight is low, or when the molecular weight of the high molecular weight components is low. These components can be adjusted to be within the range.

The lower limit of the plane orientation coefficient of the biaxially stretched laminated polypropylene film of the present invention is preferably 0.011, more preferably 0.012, and even more preferably 0.013. Within the above range, the heat resistance and rigidity of the film tend to increase.
The stretched laminated polypropylene film generally has a crystal orientation, and its direction and degree greatly affect the physical properties of the film. The degree of crystal orientation tends to vary depending on the molecular structure of the polypropylene used, the process and conditions in film production, and can be adjusted to the above range by adjusting these. The measuring method will be described later.

  The evaluation of the ink adhesion of the biaxially oriented polypropylene film of the present invention was conducted by performing a peel test of the gravure-printed printing ink and performing the number of peeled portions out of the total 25 locations. The number of peeled portions is preferably 15 or less, more preferably 5 or less, and most preferably 0. If the number is 15 or more, the degree of ink peeling becomes large, which is a problem. A method for evaluating ink adhesion will be described later.

  The lamination strength in the longitudinal direction after lamination to the biaxially oriented polypropylene film of the present invention is preferably 1.2 to 2.5 N / 15 mm, more preferably 1.3 to 2.5 N / mm, and 1.4 to 2 More preferably, 5 N / mm. A method for measuring the laminate strength will be described later.

  The dynamic friction coefficient of the biaxially oriented polypropylene film of the present invention is preferably 0.5 or less, more preferably 0.48 or less, and particularly preferably 0.45 or less. When the dynamic friction coefficient is 0.5 or less, the film can be smoothly unwound from the roll film, and printing is easy. A method for measuring the dynamic friction coefficient will be described later.

(4) Manufacturing method The biaxially stretched laminated polypropylene film of the present invention is formed by melting and extruding a polypropylene resin with an extruder to form an unstretched sheet, and stretching and heat-treating the unstretched sheet by a predetermined method. Can be obtained.
In the case of the second invention, the polypropylene material for the base layer (A) (polypropylene resin composition for the base layer (A)) and the surface layer (B) polypropylene material (polypropylene resin composition for the surface layer (B)) Each of the products can be obtained by melt-extrusion with another extruder to form a laminated unstretched sheet, and the unstretched sheet is stretched and heat-treated by a predetermined method.
The unstretched sheet can be obtained by using a plurality of extruders, feed blocks, and multi-manifolds. The melt extrusion temperature is preferably about 200 to 280 ° C.
In the second invention, in order to obtain a laminated film having a good appearance without disturbing the layer within this temperature range, the difference in viscosity (MFR) between the polypropylene raw material for the base layer (A) and the polypropylene raw material for the surface layer (B) The difference is preferably 6 g / 10 min or less. When the viscosity difference is larger than 6 g / 10 min, the layer is disturbed and the appearance is liable to be poor. More preferably, it is 5.5 g / 10 minutes or less, More preferably, it is 5 g / 10 minutes or less.

  The chill roll surface temperature is preferably 25 to 35 ° C, more preferably 27 to 33 ° C. Next, the film is stretched 3 to 8 times, preferably 3 to 7 times in the length (MD) direction with a stretching roll of 120 to 165 ° C., and subsequently 155 to 175 ° C., more preferably 160 to 163 ° C. in the TD direction. Is stretched 4 to 20 times, preferably 6 to 12 times. Further, heat fixation is performed at 165 to 176 ° C., more preferably 170 to 176 ° C., and further preferably 172 to 175 ° C. while relaxing 2 to 10%. The biaxially stretched laminated polypropylene film thus obtained can be subjected to corona discharge, plasma treatment, flame treatment, etc., if necessary, and then wound with a winder to obtain a film roll.

  The lower limit of the MD draw ratio is preferably 3 times, more preferably 3.5 times. If it is less than the above, film thickness unevenness may occur. The upper limit of the MD draw ratio is preferably 8 times, more preferably 7 times. When the above is exceeded, it may be difficult to carry out TD stretching continuously. The lower limit of the MD stretching temperature is preferably 120 ° C, more preferably 125 ° C, and even more preferably 130 ° C. If it is less than the above, the mechanical load may increase, the thickness unevenness may increase, or the film surface may be roughened. The upper limit of the MD stretching temperature is preferably 160 ° C, more preferably 155 ° C, and even more preferably 150 ° C. A higher temperature is preferable for lowering the thermal shrinkage, but it may adhere to the roll and cannot be stretched, or surface roughness may occur.

  The lower limit of the stretching ratio of TD is preferably 4 times, more preferably 5 times, and further preferably 6 times. If it is less than the above, thickness unevenness may occur. The upper limit of the TD stretch ratio is preferably 20 times, more preferably 17 times, still more preferably 15 times, and particularly preferably 12 times. If the above is exceeded, the thermal shrinkage rate may be increased or the film may be broken during stretching. The preheating temperature in TD stretching is preferably set 5 to 15 ° C. higher than the stretching temperature in order to quickly raise the film temperature in the vicinity of the stretching temperature. The TD stretching is performed at a higher temperature than the conventional biaxially oriented polypropylene film. The lower limit of the TD stretching temperature is preferably 155 ° C, more preferably 157 ° C, still more preferably 158 ° C, and particularly preferably 160 ° C. If it is less than the above, it may break without being sufficiently softened, or the thermal shrinkage rate may be increased. The upper limit of the TD stretching temperature is preferably 170 ° C, more preferably 168 ° C, and further preferably 163 ° C. In order to lower the thermal shrinkage rate, it is preferable that the temperature is higher. However, if the temperature is higher than the above, the low molecular component is melted and recrystallized to lower the orientation, and the surface may be roughened or the film may be whitened.

  The stretched film is heat-set. The heat setting can be performed at a higher temperature than the conventional biaxially oriented polypropylene film. The lower limit of the heat setting temperature is preferably 165 ° C, more preferably 166 ° C. If it is less than the above, the thermal shrinkage rate may increase. In addition, a long time treatment is required to lower the heat shrinkage rate, and productivity may be inferior. The upper limit of the heat setting temperature is preferably 176 ° C, more preferably 175 ° C. When the above is exceeded, the low molecular component may melt and recrystallize, and the surface roughness or the film may be whitened.

  It is preferable to relax at the time of heat setting. The lower limit of relaxation is preferably 2%, more preferably 3%. If it is less than the above, the thermal shrinkage rate may increase. The upper limit of relaxation is preferably 10%, more preferably 8%. When the above is exceeded, the thickness unevenness may increase.

  Furthermore, in order to reduce the thermal shrinkage rate, the film produced in the above process can be once wound up in a roll and then annealed offline. The lower limit of the offline annealing temperature is preferably 160 ° C, more preferably 162 ° C, and even more preferably 163 ° C. If it is less than the above, the effect of annealing may not be obtained. The upper limit of the offline annealing temperature is preferably 175 ° C., more preferably 174 ° C., and further preferably 173 ° C. When the above is exceeded, the transparency may decrease, or the thickness unevenness may increase.

  The lower limit of the offline annealing time is preferably 0.1 minutes, more preferably 0.5 minutes, and even more preferably 1 minute. If it is less than the above, the effect of annealing may not be obtained. The upper limit of the offline annealing time is preferably 30 minutes, more preferably 25 minutes, and further preferably 20 minutes. When the above is exceeded, productivity may be reduced.

  Hereinafter, the present invention will be described in more detail by way of examples. However, the following examples are not intended to limit the present invention, and modifications and implementations within the scope of the present invention are included in the present invention. In addition, the measuring method of the film physical property obtained by the Example and the comparative example is as follows.

1) Stereoregularity The mesopentad fraction ([mmmm]%) was measured using 13C-NMR. The mesopentad fraction was calculated according to the method described in “Zambelli et al., Macromolecules, Vol. 6, 925 (1973)”. 13C-NMR measurement was performed at 110 ° C. using “AVANCE 500” manufactured by BRUKER, and dissolving 200 mg of a sample in an 8: 2 (volume ratio) mixture of o-dichlorobenzene and heavy benzene at 135 ° C.

2) Melt flow rate (MFR; g / 10 min)
According to JIS K7210, the temperature was 230 ° C. and the load was 2.16 kgf.
The required amount of pellet (powder) was used as the resin.
After the required amount of the film was cut out, a sample cut into about 5 mm square was used.

3) Molecular weight and molecular weight distribution The molecular weight and molecular weight distribution were determined on the basis of monodisperse polystyrene using gel permeation chromatography (GPC) and converted to polypropylene values. The measurement conditions such as the column used and the solvent in GPC measurement are as follows.
Solvent: 1,2,4-trichlorobenzene Column: TSKgel GMHHR-H (20) HT × 3
Flow rate: 1.0 ml / min
Detector: RI
Measurement temperature: 140 ° C

The number average molecular weight (Mn), the mass average molecular weight (Mw), and the molecular weight distribution are respectively expressed by the following formulas depending on the molecular number (Ni) of the molecular weight (Mi) at each elution position of the GPC curve obtained through the molecular weight calibration curve. Defined.
Number average molecular weight: Mn = Σ (Ni · Mi) / ΣNi
Mass average molecular weight: Mw = Σ (Ni · Mi ² ) / Σ (Ni · Mi)
Molecular weight distribution: Mw / Mn
When the baseline was not clear, the baseline was set in the range from the elution peak closest to the elution peak of the standard substance to the lowest position of the bottom of the high molecular weight side.

4) Thickness The thickness of each of the base layer (A) and the surface layer (B) was measured by cutting a cross section of a biaxially stretched laminated polypropylene film solidified with a modified urethane resin with a microtome and observing with a differential interference microscope. .

5) Thermal shrinkage (%)
Based on JIS Z1712, it measured by the following method. The film was cut into a width of 20 mm and a length of 200 mm in each of the MD direction and the TD direction, suspended in a hot air oven at 150 ° C. and heated for 5 minutes. The length after heating was measured, and the thermal contraction rate was determined by the ratio of the contracted length to the original length.

6) Tensile modulus (Young's modulus (unit: GPa))
The Young's modulus in the MD direction and TD direction of the film was measured at 23 ° C. in accordance with JIS K7127.
7) Ring crash (g)
Using a digital ring crush tester (manufactured by Tester Sangyo Co., Ltd.), prepare a film sample size of 12.7 mm x 152 mm, set an attachment spacer on the sample table in accordance with the thickness of the film sample, and MD, TD direction In each, insert a film sample along the circumference. At 23 ° C., the compressed plate is moved down at a speed of 12 mm / min. The maximum load at the time of compression with was used as a ring crush measurement value.

8) Haze (Unit:%)
It measured according to JIS K7105.

9) Coefficient of dynamic friction According to JIS K7125, the surfaces of the film subjected to corona treatment were overlapped and measured at 23 ° C.
10) Impact resistance It measured at 23 degreeC using the Toyo Seiki film impact tester.

11) Refractive index and plane orientation coefficient Measured using an Atago Abbe refractometer according to JIS K7142-1996 5.1 (Method A). The refractive indexes along the MD and TD directions were Nx and Ny, respectively, and the refractive index in the thickness direction was Nz. The plane orientation coefficient (ΔP) was determined by (Nx + Ny) / 2−Nz.

12) Surface roughness The surface roughness of the obtained film was evaluated using a three-dimensional roughness meter (manufactured by Kosaka Laboratories, model number ET-30HK) at a stylus pressure of 20 mg and measured length in the X direction. Measurement was performed with 1 mm, feed rate of 100 μm / second, feed pitch of 2 μm in the Y direction, 99 recording lines, magnification in the height direction of 20000 times, and cutoff of 80 μm.
Three-dimensional roughness was measured three times, and the arithmetic average roughness (SRa), center plane peak height (SRp), and center plane valley depth (SRv) were evaluated by the average values.

13) Surface resistivity (LogΩ)
In accordance with JIS K6911, the film was aged at 23 ° C. for 24 hours, and then the corona-treated surface of the film was measured.

14) Wetting tension (mN / m)
In accordance with JIS K6768: 1999, the film was aged at 23 ° C. and a relative humidity of 50% for 24 hours, and then the corona-treated surface of the film was measured by the following procedure.
1) Measurement is performed in a standard test room atmosphere (see JIS K7100) at a temperature of 23 ° C and a relative humidity of 50%.
2) Place the test piece on the substrate of the hand coater (4.1), drop a few drops of the test mixture on the test piece and immediately pull the wire bar to spread.
When using a cotton swab or brush extend the test mixture, the liquid is spread quickly to at least 6 cm ² or more areas. The amount of liquid should be such that a thin layer is formed without creating a pool.
The wetting tension is determined by observing the liquid film of the test liquid mixture in a bright place and after 3 seconds. It is wet that it keeps the state when applied for 3 seconds or more without tearing the liquid film. If the wetting is maintained for 3 seconds or more, the process proceeds to the liquid mixture having the next highest surface tension. Conversely, if the liquid film is broken in 3 seconds or less, the process proceeds to the next liquid mixture having the lower surface tension.
Repeat this procedure and select a mixture that can wet the surface of the specimen accurately in 3 seconds.
3) Use a new cotton swab for each test. Brushes or wire bars are washed with methanol and dried after each use because residual liquid changes composition and surface tension by evaporation.
4) Perform an operation of selecting a mixed solution that can wet the surface of the test piece in 3 seconds at least three times. The surface tension of the mixture thus selected is reported as the wetting tension of the film.

15) Ink adhesion On the film, gravure printing (printing ink amount 2 g / m ² ) was carried out at a speed of 50 m / min using a gravure printer (manufactured by Mitani Iron Works). The ink at this time is a water-based ink (manufactured by Dainippon Ink & Chemicals, Inc .: trade name Eco Fine 709 White). Using this print sample, it was evaluated by grid peel (2 mm square x 25 pieces, 90 ° peel method using cello tape (registered trademark) 18 mm width manufactured by Nichiban Co., Ltd.). The ranking was done.
Cross-section peeling part: 0 ·····: Excellent in printing ink adhesion.
１〜 1 to 5 ·····: Good printing ink adhesion.
６ 6 to 15 ・ ・ ・ Δ: Poor adhesion to printing ink.
〃 1 or more ········ ×: No printing ink adhesion.

16) Laminate strength The laminate strength was measured by the following procedure.
1) Preparation of a laminate film with a sealant film A continuous dry laminating machine was used as follows.
The corona surface of the biaxially oriented polypropylene film obtained in Examples and Comparative Examples was gravure coated with an adhesive so that the coating amount upon drying was 3.0 g / m ^2, and then led to a drying zone at 80 ° C. for 5 seconds. And dried. Subsequently, it was bonded to a sealant film between rolls provided on the downstream side (roll pressure 0.2 MP, roll temperature: 60 ° C.). The obtained laminate film was subjected to an aging treatment at 40 ° C. for 3 days while being wound up.
The adhesive was obtained by mixing 17.9% by mass of a main agent (manufactured by Toyo Morton, TM329), 17.9% by mass of a curing agent (CAT8B, manufactured by Toyo Morton) and 64.2% by mass of ethyl acetate. An ether-based adhesive was used, and a non-biaxially oriented polypropylene film (Pyrene (registered trademark) CTP1128, thickness 30 μm) manufactured by Toyobo Co., Ltd. was used as the sealant film.
2) Measurement of laminate strength The laminate film obtained above was cut into a strip shape (length 200 mm, width 15 mm) having a long side in the longitudinal direction of a biaxially oriented polypropylene film, and a tensile tester (Tensilon, manufactured by Orientec Co., Ltd.) ) Was used to measure the peel strength (N / 15 mm) when peeled T-shaped at a tensile rate of 200 mm / min in an environment of 23 ° C. The measurement was performed three times, and the average value was taken as the laminate strength.

Example 1
A mixture of 99% by weight of the polypropylene homopolymer PP-1 shown in Table 1 and 1% by weight of an antistatic agent (stearyl diethanolamine stearate (Matsumoto Yushi Co., Ltd. KYM-4K)) was used.
This mixture was melted at 250 ° C. using a 60 mm extruder, the raw resin was coextruded from a T-die into a sheet shape, cooled and solidified with a 30 ° C. cooling roll, and then 4. in the longitudinal direction (MD) at 135 ° C. Stretched 5 times. Next, in the tenter, both ends in the film width direction are sandwiched between clips, preheated at 175 ° C., stretched 8.2 times in the width direction (TD) at 160 ° C., and relaxed by 6.7% in the width direction (TD). And heat-fixed at 170 ° C. The film-forming conditions at this time were set as film-forming conditions a and are shown in Table 2.
After the corona treatment was performed on the surface of one side of the obtained biaxially oriented polypropylene film using a corona treatment machine manufactured by Sophtal Corona & Plasma GmbH under the condition of an applied current value of 0.75 A, a winder The biaxially stretched monolayer polypropylene film of the present invention was taken up by Table 3 shows the physical properties of the obtained film.

(Example 2)
The polypropylene homopolymer PP-1 shown in Table 1 was changed to polypropylene resin PP-2, and using a 60 mm extruder, the mixed raw material was melted at 250 ° C., and co-extruded into a sheet form from a T-die. After cooling and solidifying with a cooling roll, the film was stretched 4.5 times in the longitudinal direction (MD) at 125 ° C. Next, in the tenter, the film width direction both ends are clipped, preheated at 170 ° C., stretched 8.2 times in the width direction (TD) at 158 ° C., and relaxed by 6.7% in the width direction (TD). A biaxially stretched monolayer polypropylene film was obtained in the same manner as in Example 1 except that the film was heat-set at 165 ° C. The film forming conditions at this time were set as film forming conditions b and are shown in Table 2. Table 3 shows the physical properties of the obtained film.

(Example 3)
In the base material layer (A), 99% by weight of the polypropylene homopolymer PP-1 shown in Table 1 and 1% by weight of antistatic agent (stearyl diethanolamine stearate (Matsumoto Yushi Co., Ltd. KYM-4K)) are mixed. What was done was used. The surface layer (B) was 99.7% by weight of the polypropylene homopolymer PP-1 shown in Table 1, and 0.3% of an antiblocking agent (commercially available silica particles (average particle size: 1.3 μm)). What was blended by mass% was used.
The mixed raw material used for the base material layer (A) is a 60 mm extruder, and the mixed raw material used for the surface layer (B) is a 65 mm extruder. After co-extrusion and cooling and solidifying with a 30 ° C. cooling roll, the film was stretched 4.5 times in the longitudinal direction (MD) at 135 ° C. Next, in the tenter, both ends in the film width direction are sandwiched between clips, preheated at 175 ° C., stretched 8.2 times in the width direction (TD) at 160 ° C., and relaxed by 6.7% in the width direction (TD). And heat-fixed at 170 ° C. A biaxially oriented laminated polypropylene film according to the present invention in which the base material layer (A) and the surface layer (B) were laminated one by one was obtained by film formation under the film production condition a shown in Table 2 and winding with a winder. . The surface of the surface layer (B) of the obtained biaxially oriented polypropylene film is subjected to corona treatment using a corona treatment machine manufactured by Sophthal Corona & Plasma GmbH under the condition of applied current value: 0.75A. After the application, the one wound with a winder was used as the biaxially stretched single layer polypropylene film of the present invention. Table 3 shows the physical properties of the obtained film.

(Example 4)
A biaxially stretched laminated polypropylene film was obtained in the same manner as in Example 3 except that the raw material used for the base material layer (A) did not contain an antistatic agent. Table 3 shows the physical properties of the obtained film.

(Example 5)
In the base material layer (A), 99% by mass of the polypropylene homopolymer PP-1 shown in Table 1 and 1% by mass of (stearyldiethanolamine stearate (KYM-4K), Matsumoto Yushi Co., Ltd.) are added to the antistatic agent. A mixture was used. The surface layer (B) contains 48.7% by weight of the polypropylene homopolymer PP-6 shown in Table 1 and 51% by weight of the ethylene copolymer polypropylene polymer PP-7 shown in Table 1 as an antiblocking agent. In the same manner as in Example 3, except that a commercially available silica particle (average particle size: 1.3 μm) was mixed with a composition mixed at a ratio of 0.3% by mass, A biaxially oriented laminated polypropylene film was obtained.

(Example 6)
A biaxially stretched single layer polypropylene film was obtained in the same manner as in Example 1 except that the film thickness was 30 μm. Table 3 shows the physical properties of the obtained film.

(Example 7)
A biaxially stretched single layer polypropylene film was obtained in the same manner as in Example 1 except that the film thickness was 40 μm. Table 3 shows the physical properties of the obtained film.

(Comparative Example 1)
A biaxially stretched monolayer polypropylene film was obtained in the same manner as in Example 1 except that the polypropylene resin PP-1 shown in Table 1 was changed to the polypropylene resin PP-3 shown in Table 1. The physical properties of the obtained film are as shown in Table 4.

(Comparative Example 2)
A biaxially stretched single-layer polypropylene film was formed in the same manner as in Example 1 except that the polypropylene resin PP-1 shown in Table 1 was changed to the polypropylene resin PP-4 shown in Table 1. I couldn't get a film.

(Comparative Example 3)
A biaxially stretched single-layer polypropylene film was obtained in the same manner as in Example 1 except that the polypropylene resin PP-1 shown in Table 1 was changed to the polypropylene resin PP-5 shown in Table 1. The physical properties of the obtained film are as shown in Table 4.

(Comparative Example 4)
The polypropylene resin PP-1 shown in Table 1 was changed to the polypropylene resin PP-6 shown in Table 1, and the raw resin was melted at 250 ° C. using a 60 mm extruder, and coextruded into a sheet form from a T die, 30 After cooling and solidifying with a cooling roll at ° C, the film was stretched 4.5 times in the longitudinal direction (MD) at 125 ° C. Next, in the tenter, the film width direction both ends are clipped, preheated at 170 ° C., stretched 8.2 times in the width direction (TD) at 158 ° C., and relaxed by 6.7% in the width direction (TD). A biaxially stretched monolayer polypropylene film was obtained in the same manner as in Example 1 except that the film was heat-set at 165 ° C. The physical properties of the obtained film are as shown in Table 4.

(Comparative Example 5)
The polypropylene resin PP-1 shown in Table 1 was changed to the polypropylene resin PP-8 shown in Table 1, and the raw resin was melted at 250 ° C. using a 60 mm extruder, and coextruded into a sheet form from a T die, 30 After cooling and solidifying with a cooling roll at 0 ° C., it was stretched 4.5 times in the longitudinal direction (MD) at 140 ° C. Next, in the tenter, both ends of the film width direction are sandwiched between clips, preheated at 170 ° C., stretched 8.2 times in the width direction (TD) at 160 ° C., and relaxed by 6.7% in the width direction (TD). A biaxially stretched single-layer polypropylene film was obtained in the same manner as in Example 1 except that it was heat-set at 168 ° C. The film forming conditions at this time were set as film forming conditions c and are shown in Table 2. The physical properties of the obtained film are as shown in Table 4.

(Comparative Example 6)
The polypropylene resin PP-1 shown in Table 1 was changed to the polypropylene resin PP-9 shown in Table 1, and the raw resin was melted at 250 ° C. using a 60 mm extruder, and coextruded into a sheet form from a T die, 30 After cooling and solidifying with a cooling roll at ° C, the film was stretched 4.5 times in the longitudinal direction (MD) at 135 ° C. Next, in the tenter, both ends of the film width direction are sandwiched between clips, preheated at 170 ° C., stretched 8.2 times in the width direction (TD) at 160 ° C., and relaxed by 6.7% in the width direction (TD). A biaxially stretched single-layer polypropylene film was obtained in the same manner as in Example 1 except that it was heat-set at 168 ° C. The film forming conditions at this time are shown as Table 2 as film forming conditions d. The physical properties of the obtained film are as shown in Table 4.

The biaxially oriented polypropylene films obtained in Examples 1 to 7 had a small heat shrinkage rate and a large Young's modulus. Especially, the laminated | multilayer film obtained in Examples 3-5 became a film with favorable laminate strength and ink adhesiveness.
On the other hand, the film obtained in Comparative Example 1 had a large thermal contraction rate in the width direction (TD). The film obtained in Comparative Example 3 had a large thermal shrinkage in the width direction (TD) and a small Young's modulus in the width direction (TD). The film obtained in Comparative Example 4 is a film having a large thermal contraction rate and a small Young's modulus in the width direction (TD) and the longitudinal direction (MD).
The film obtained in Comparative Example 5 had a small Young's modulus in the width direction (TD). The film obtained in Comparative Example 6 had a large thermal shrinkage in the width direction (TD).

Since the biaxially stretched laminated polypropylene film of the present invention has higher heat resistance and rigidity, heat loss wrinkles are smaller, and it is difficult to break, it is excellent in workability.
The biaxially oriented polypropylene film of the present invention can be used for labeling as well as food packaging used for standing pouches and the like.

Claims (5)

A biaxially oriented stretched polypropylene film characterized in that the polypropylene resin constituting the film satisfies the following conditions 1) to 4), and the lower limit of the plane orientation coefficient of the film is 0.0125.
1) The lower limit of the mesopentad fraction is 96%.
2) The upper limit of the amount of copolymerization monomers other than propylene is 0.1 mol%.
3) The mass average molecular weight (Mw) / number average molecular weight (Mn) is 3.0 or more and 5.4 or less. 4) The melt flow rate (MFR) measured at 230 ° C. and 2.16 kgf is 6.5 g / 10 min or more and 9.0 g / 10 min or less. It has a base material layer (A) having a polypropylene resin as a main component and a surface layer (B) having a polypropylene resin as a main component on at least one surface of the base material layer (A). That the polypropylene resin that constitutes a) satisfies the following conditions 1) to 4):
And the minimum of the plane orientation coefficient of a film is 0.0125, The biaxially oriented polypropylene film characterized by the above-mentioned.
1) The lower limit of the mesopentad fraction is 96%.
2) The upper limit of the amount of copolymerization monomers other than propylene is 0.1 mol%.
3) The mass average molecular weight (Mw) / number average molecular weight (Mn) is 3.0 or more and 5.4 or less. 4) The melt flow rate (MFR) measured at 230 ° C. and 2.16 kgf is 6.2 g / 10 min or more and 9.0 g / 10 min or less.   The biaxially oriented polypropylene film according to claim 1 or 2, wherein a heat shrinkage rate at 150 ° C in the longitudinal and transverse directions of the film is 8% or less.   The biaxially oriented polypropylene film according to any one of claims 1 to 3, wherein the film has a tensile modulus in the machine direction of 2.0 GPa or more and a tensile modulus in the transverse direction of the film of 4.5 GPa or more.   The haze value of a film is 5% or less, The biaxially oriented polypropylene film in any one of Claims 1-4.