TW201801928A - Biaxially oriented polypropylene film - Google Patents

Abstract

In order to provide a biaxially stretched polypropylene film having higher thermal resistance and rigidity, this biaxially oriented polypropylene film is characterized by: a polypropylene resin constituting the film fulfilling conditions 1)-4); and the lower limit of a plane orientation coefficient for the film being 0.0125. 1) The mesopentad fraction lower limit being 96%. 2) The upper limit for the amount of copolymerized monomers other than propylene being 0.1 mol%. 3) Mass average molecular weight (Mw)/number average molecular weight (Mn) being 3.0-5.4. 4) The melt flow rate (MFR) measured at 230 DEG C and 2.16 kgf being 6.2-9.0 g/10 min.

Description

Biaxially oriented polypropylene film

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

Previously, polypropylene stretch films have been widely used in a wide range of applications such as food or various product packaging, electrical insulation, and surface protection films. However, the previous polypropylene film has a shrinkage of tens of percent at 150 ° C. Compared with PET (Polyethylene terephthalate) films, it has lower heat resistance and lower rigidity. , So the use is limited.

Various techniques for improving the physical properties of polypropylene films have been proposed. For example, the following technique is known: using polypropylene containing approximately equal amounts of high molecular weight components and low molecular weight components (or less low molecular weight components), wide molecular weight distribution, and few decalin soluble components to make a film, thereby obtaining rigidity and Balance of processability (Patent Document 1). However, in this technology, the heat resistance at a high temperature of more than 150 ° C is still not sufficient, and a polypropylene film having high heat resistance, impact resistance, and transparency is not known.

The applicant based on the above-mentioned prior art has conducted diligent research, and as a result, successfully achieved the following: by using a polypropylene polymer having a meso pentad content of 96% or more, a highly rigid and Stretchable polypropylene film with high heat resistance (Patent Document 2). However, this film has room for improvement in terms of heat resistance.

[Prior technical literature]

[Patent Literature]

Patent Document 1: Japanese Patent Publication No. 2008-540815.

Patent Document 2: WO2015 / 012324.

In view of the foregoing, it is an object of the present invention to provide a biaxially stretched laminated polypropylene film having higher heat resistance and rigidity.

The present invention that can solve the above-mentioned problems is a biaxially oriented polypropylene film, which is characterized in that the polypropylene resin constituting the film satisfies the following conditions 1) to 4) and the lower limit of the surface orientation coefficient of the film is 0.0125.

1) The lower limit of the meso pentad component ratio is 96%.

2) The upper limit of the amount of comonomers 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) MFR (Melt Flow Rate) measured at 230 ° C and 2.16 kgf is 6.2 g / 10 minutes or more and 9.0 g / 10 minutes or less.

In addition, a second invention capable of solving the above-mentioned problems is a biaxially oriented polypropylene film, which is characterized by having a base material layer (A) containing a polypropylene-based resin as a main component and at least one base material layer (A). A surface layer (B) having polypropylene resin as a main component on one surface, and the polypropylene resin constituting the base material layer (A) satisfies the following conditions 1) to 4), and the lower limit of the surface alignment coefficient of the film is 0.0125 .

1) The lower limit of the meso pentad component ratio is 96%.

2) The upper limit of the amount of comonomers 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 minutes or more and 9.0 g / 10 minutes or less.

In this case, it is suitable that the thermal shrinkage of the film at 150 ° C in the longitudinal and transverse directions is 8% or less.

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

In this case, it is suitable that the haze value of the aforementioned film is 5% or less.

The biaxially oriented polypropylene film of the present invention has a small molecular weight distribution and less entanglement of molecular chains, so that the orientation becomes stronger, has higher thermal dimensional stability and lateral rigidity, and has less negative thermal wrinkles and is less prone to bending. Therefore, the film processability is very excellent.

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 surface alignment coefficient of the film is 0.0125.

1) The lower limit of the meso pentad component ratio is 96%.

2) The upper limit of the amount of comonomers 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 minutes or more and 9.0 g / 10 minutes or less.

In addition, the biaxially oriented polypropylene film of the second invention is characterized in that it has a base material layer (A) containing a polypropylene-based resin as a main component and at least one surface of the base material layer (A) is made of a polypropylene-based resin. The surface layer (B) of the main component, the polypropylene resin constituting the base material layer (A) satisfy the following conditions 1) to 4), and the lower limit of the surface alignment coefficient of the film is 0.0125.

1) The lower limit of the meso pentad component ratio is 96%.

2) The upper limit of the amount of comonomers 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 minutes or more and 9.0 g / 10 minutes or less.

Further details will be described below.

(1) As the polypropylene resin used in the first invention, a polypropylene resin copolymerized with ethylene and / or an α-olefin having a carbon number of 4 or more at 0.5 mol% or less can also be used. Such copolymerized polypropylene resin is also included in the polypropylene resin (hereinafter referred to as polypropylene resin) of the present invention. The copolymerization component is preferably 0.3 mol% or less, more preferably 0.1 mol% or less, and most preferably a completely homopolypropylene resin containing no copolymerization component.

When ethylene and / or an α-olefin having 4 or more carbon atoms are copolymerized in an amount exceeding 0.5 mol%, the crystallinity or rigidity may be too low, and the thermal shrinkage at high temperatures may increase. Such resins can also be used in combination.

As an index of the stereoregularity of the polypropylene resin, the meso pentad component ratio ([mmmm]%) measured by ¹³ C-NMR (Nuclear Magnetic Resonance) is preferably 96% to 99.5%. It is more preferably 97% or more, and still more preferably 98% or more. When the meso pentad rate of the polypropylene of the base material layer (A) is small, there is a possibility that the elastic modulus decreases and the heat resistance becomes insufficient. 99.5% is the actual upper limit.

The Mw / Mn as an index of the molecular weight distribution is preferably 3.0 to 5.4 for the polypropylene resin. It is more preferably 3.0 to 5.0, further preferably 3.2 to 4.5, and even more preferably 3.3 to 4.0.

If the overall Mw / Mn of the polypropylene resin constituting the biaxially oriented polypropylene film of the present invention exceeds 5.4, the Mw / Mn becomes excessively large. If this is the case, there is a tendency that the high-molecular-weight component increases, and the heat shrinkage rate may increase The tensile elastic modulus (Young's modulus) in the width direction (TD (Transverse Direction)) may be small. When there is a molecular weight distribution, although a high molecular weight component promotes crystallization of a low molecular weight component, there is also a tendency that the intertwining of molecules becomes strong, and even if the crystallinity is high, the thermal shrinkage ratio tends to increase.

If the overall Mw / Mn of the polypropylene resin constituting the biaxially oriented polypropylene film of the present invention is less than 3.0, film formation becomes difficult.

Mw refers to a mass average molecular weight, and Mn refers to an index molecular weight average molecular weight.

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

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

When measuring the cumulative GPC (Gel Permeation Chromatography; gel permeation chromatography) cumulative curve of the polypropylene resin constituting the biaxially oriented polypropylene film of the first invention, the lower limit of the amount of components having a molecular weight of 100,000 or less is preferably 35 mass%, more preferably 38 mass%, even more preferably 40 mass%, particularly preferably 41 mass%, and most preferably 42 mass%.

On the other hand, the upper limit of the amount of components having a molecular weight of 100,000 or less in the cumulative GPC curve is preferably 65% by mass, more preferably 60% by mass, even more preferably 58% by mass, particularly preferably 56% by mass, and most preferably 55 mass%. If it is the said range, extending | stretching becomes easy, thickness unevenness will become small, or it becomes easy to raise extending | stretching temperature or heat-fixing temperature, and it can suppress thermal contraction rate to be lower.

The melt flow rate (MFR; 230 ° C, 2.16 kgf) of the polypropylene resin at this time is preferably 6.2 g / 10 minutes to 10.0 g / 10 minutes.

The lower limit of the MFR of the polypropylene resin is more preferably 6.5 g / 10 minutes, more preferably 7 g / 10 minutes, and even more preferably 7.5 g / 10 minutes. The upper limit of the MFR of the polypropylene resin is more preferably 9 g / 10 minutes, more preferably 8.5 g / 10 minutes, and even more preferably 8.2 g / 10 minutes.

If the melt flow rate (MFR; 230 ° C, 2.16 kgf) is 6.2 g / 10 minutes or more, the heat shrinkage rate at high temperature can be further reduced. Furthermore, the degree of alignment of the film produced by stretching is enhanced, so that the rigidity of the film, especially the tensile elastic modulus (Young's modulus) in the width (TD) direction becomes higher. In addition, if the melt flow rate (MFR; 230 ° C, 2.16 kgf) is 9.0 g / 10 minutes or less, it is easy to form a film without breaking.

Furthermore, the molecular weight distribution of the polypropylene resin can be adjusted in the following manner Integration: use a series of equipment (plant) to polymerize components with different molecular weights in multiple stages; or use an off-line method to blend components with different molecular weights; or blend catalysts with different properties for polymerization ; Or use a catalyst that achieves the desired molecular weight distribution.

The polypropylene resin used in the present invention can be obtained by polymerizing the raw material propylene using a known catalyst such as a Ziegler-Natta catalyst or a metallocene catalyst. Among them, in order to eliminate heterogeneous bonding, a Ziegler-Natta catalyst is used, and it is preferable to use a catalyst capable of achieving polymerization with high stereoregularity.

As the polymerization method of propylene, any known method may be adopted, and examples thereof include a method of polymerization in an inactive solvent such as hexane, heptane, toluene, xylene, and the like; and a method of polymerization in a liquid monomer. ; A method of adding a catalyst to a monomer of a gas and polymerizing in a gas phase state; or a method of combining these methods to perform polymerization and the like.

The polypropylene resin may contain additives or other resins. Examples of the additives include antioxidants, ultraviolet absorbers, nucleating agents, adhesives, mothproofing agents, flame retardants, and inorganic or organic fillers. Examples of other resins include polypropylene resins other than the polypropylene resin used in the present invention, random copolymers as copolymers of propylene and ethylene and / or α-olefins having 4 or more carbon atoms, or various elastomers. . These additives or other resins can also be polymerized sequentially using a multi-stage reactor, or blended with polypropylene resin using a Henschel mixer, or polypropylene can be used in advance to make The masterbatch particles produced by the melt-kneading machine are diluted so as to have a predetermined concentration, or all the amounts are melt-kneaded before use.

(2) As the polypropylene resin used in the substrate layer (A) of the second invention, a polypropylene resin copolymerized with ethylene and / or an α-olefin having 4 or more carbons at 0.5 mol% or less may be used. Such copolymerized polypropylene resin is also included in the polypropylene resin (hereinafter referred to as polypropylene resin) of the present invention. The copolymerization component is preferably 0.3 mol% or less, more preferably 0.1 mol% or less, and most preferably a completely homopolypropylene resin containing no copolymerization component.

When ethylene and / or an α-olefin having 4 or more carbon atoms are copolymerized in an amount exceeding 0.5 mol%, the crystallinity or rigidity may be too low, and the thermal shrinkage at high temperatures may increase. Such a resin may be used in combination.

The meso pentad fraction ([mmmm]%) as an index of the stereoregularity of the polypropylene resin measured by ¹³ C-NMR is preferably 96% to 99.5%. It is more preferably 97% or more, and still more preferably 98% or more. When the meso pentad rate of the polypropylene of the base material layer (A) is small, there is a possibility that the elastic modulus decreases and the heat resistance becomes insufficient. 99.5% is the actual upper limit.

The Mw / Mn as an index of the molecular weight distribution is preferably 3.0 to 5.4 for the polypropylene resin. It is more preferably 3.0 to 5.0, further preferably 3.2 to 4.5, and even more preferably 3.3 to 4.0.

If the overall Mw / Mn of the polypropylene resin constituting the base material layer (A) exceeds 5.4, the Mw / Mn becomes excessively large, and if this is the case, the following tends to be high: As the molecular weight component increases, the thermal shrinkage ratio increases, or the tensile elastic modulus (Young's modulus) in the width (TD) direction may decrease.

When there is a molecular weight distribution, although a high molecular weight component promotes crystallization of a low molecular weight component, there is also a tendency that the intertwining of molecules becomes strong, and even if the crystallinity is high, the thermal shrinkage ratio tends to increase.

If the overall Mw / Mn of the polypropylene resin constituting the biaxially oriented polypropylene film of the present invention is less than 3.0, film formation becomes difficult. Mw refers to a mass average molecular weight, and Mn refers to an index molecular weight average molecular weight.

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

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

When measuring the cumulative gel permeation chromatography (GPC) curve of the polypropylene resin constituting the base material layer (A) as a whole, the lower limit of the amount of components having a molecular weight of 100,000 or less is preferably 35% by mass, more preferably 38% The mass% is preferably 40 mass%, more preferably 41 mass%, and most preferably 42 mass%.

On the other hand, the molecular weight in the GPC cumulative curve is less than 100,000. The upper limit of the amount is preferably 65% by mass, more preferably 60% by mass, even more preferably 58% by mass, even more preferably 56% by mass, and most preferably 55% by mass. If it is the said range, extending | stretching becomes easy, thickness unevenness will become small, or it becomes easy to raise extending | stretching temperature or heat-fixing temperature, and it can suppress thermal contraction rate to be lower.

The melt flow rate (MFR; 230 ° C, 2.16 kgf) of the polypropylene resin at this time is preferably 6.2 g / 10 minutes to 10.0 g / 10 minutes.

The lower limit of the MFR of the polypropylene resin is more preferably 6.5 g / 10 minutes, more preferably 7 g / 10 minutes, and even more preferably 7.5 g / 10 minutes. The upper limit of the MFR of the polypropylene resin is more preferably 9 g / 10 minutes, more preferably 8.5 g / 10 minutes, and even more preferably 8.2 g / 10 minutes.

If the melt flow rate (MFR; 230 ° C, 2.16 kgf) is 6.2 g / 10 minutes or more, the heat shrinkage rate at high temperature can be further reduced. Furthermore, the degree of alignment of the film produced by stretching is enhanced, so the rigidity of the film, especially the tensile elastic modulus (Young's modulus) in the width (TD) direction becomes higher. In addition, if the melt flow rate (MFR; 230 ° C, 2.16 kgf) is 9.0 g / 10 minutes or less, it is easy to form a film without breaking.

Furthermore, the molecular weight distribution of polypropylene resin can be adjusted by: using a series of plants to polymerize components with different molecular weights in multiple stages; or using an off-line method to mix components with different molecular weights using a kneading machine Blending; or blending catalysts with different properties for polymerization; or using catalysts that can achieve the desired molecular weight distribution.

The polypropylene resin used in the substrate layer (A) can be obtained by using Ziegler- A known catalyst such as a Ziegler-Natta catalyst or a metallocene catalyst is obtained by polymerizing propylene as a raw material. Among them, in order to eliminate heterogeneous bonding, a Ziegler-Natta catalyst is used, and it is preferable to use a catalyst capable of achieving polymerization with high stereoregularity.

As the polymerization method of propylene, any known method may be adopted, and examples thereof include a method of polymerization in an inactive solvent such as hexane, heptane, toluene, xylene, and the like; and a method of polymerization in a liquid monomer. ; A method of adding a catalyst to a monomer of a gas and polymerizing in a gas phase state; or a method of combining these methods to perform polymerization and the like.

The polypropylene resin may contain additives or other resins. Examples of the additives include antioxidants, ultraviolet absorbers, nucleating agents, adhesives, mothproofing agents, flame retardants, and inorganic or organic fillers. Examples of other resins include polypropylene resins other than the polypropylene resin used in the present invention, random copolymers as copolymers of propylene and ethylene and / or α-olefins having 4 or more carbon atoms, or various elastomers. . These additives or other resins can also be sequentially polymerized using a multi-stage reactor, or blended with a polypropylene resin using a Henschel mixer, or master batch pellets made using a melt-kneading machine in advance using polypropylene to become predetermined It is used in the form of concentration dilution, or all amounts are melt-kneaded beforehand.

(3) The surface roughness of the surface 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 adhesiveness with printing ink or the adhesive used for laminating with other component films Adhesion is insufficient, and if it exceeds 0.40 μm, problems of color rendering and discoloration occur.

In order that the surface roughness of the surface of the surface layer (B) is 0.027 μm or more and 0.40 μm or less, it is preferable to use a mixture of two or more polypropylene resins having different melt flow rates (MFR) as the surface layer (B). Polypropylene resin composition. In this case, the difference in MFR is preferably 3 g / 10 minutes or more, and more preferably 3.5 g / 10 minutes or more.

It is estimated that by using such a mixture, the surface roughness of the surface of the surface layer (B) becomes 0.027 μm or more due to the difference in the crystallization speed.

As the polypropylene resin having a large MFR, polypropylene in which ethylene and / or an α-olefin having 4 or more carbon atoms are copolymerized may be used. Examples of the α-olefin having 4 or more carbon atoms include 1-butene, 1-hexene, 4-methyl-1-pentene, and 1-octene.

In addition, as the polypropylene resin having a small MFR, polypropylene in which ethylene and / or an α-olefin having 4 or more carbon atoms are copolymerized may be used. Examples of the α-olefin having 4 or more carbon atoms include 1-butene, 1-hexene, 4-methyl-1-pentene, and 1-octene.

Moreover, maleic acid etc. which have a polarity can also be used as another copolymerization component.

The ethylene or α-olefin having 4 or more carbon atoms and other copolymerization components are preferably 8.0 mol% or less in total. When copolymerization exceeds 8.0 mol%, a film may become white and it may become a bad appearance, or adhesiveness may arise, and it may become difficult to form a film.

These resins may be used by mixing two or more kinds. Blend In this case, each resin may be copolymerized in excess of 8.0 mol%, and the blend is preferably based on monomer units and monomers other than propylene are 8.0 mol% or less.

The polypropylene resin composition of the surface layer (B) preferably has an MFR of 1.0 g / 10 minutes to 8 g / 10 minutes. The lower limit of the MFR of the polypropylene resin composition of the surface layer (B) is more preferably 2 g / 10 minutes, and even more 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 even more preferably 6.0 g / 10 minutes. If it is this range, film-forming property will also be favorable, and the thermal shrinkage rate which can maintain high temperature is also small. If the MFR of the polypropylene resin composition of the surface layer (B) is less than 1.0 g / 10 minutes, when the MFR of the polypropylene of the substrate layer (A) is large, the substrate layer (A) and the surface layer (B ) Increases the viscosity difference, so unevenness (original 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 adhesiveness to the cooling roller may be deteriorated, and air may be drawn in and the smoothness may be deteriorated. This air may become the starting point of shortcomings.

The polypropylene resin used in the surface layer (B) can be obtained by polymerizing raw material propylene using a known catalyst such as a Ziegler-Natta catalyst or a metallocene catalyst. Among them, in order to eliminate heterogeneous bonding, a Ziegler-Natta catalyst is used, and it is preferable to use a catalyst capable of achieving polymerization with high stereoregularity.

As the polymerization method of propylene, any known method may be adopted, and examples thereof include a method of polymerization in an inactive solvent such as hexane, heptane, toluene, xylene, and the like; and a method of polymerization in a liquid monomer. Yu Qi A method in which a catalyst is added to a monomer of a polymer and polymerization is performed in a gas phase state; or a method in which these methods are combined to perform polymerization.

The surface layer (B) may contain additives or other resins. Examples of the additives include antioxidants, ultraviolet absorbers, nucleating agents, adhesives, mothproofing agents, flame retardants, and inorganic or organic fillers. Examples of other resins include polypropylene resins other than the polypropylene resin used in the present invention, random copolymers as copolymers of propylene and ethylene and / or α-olefins having 4 or more carbon atoms, or various elastomers. . These additives or other resins can be polymerized sequentially using a multi-stage reactor, or blended with polypropylene resins using a Henschel mixer, or masterbatch pellets made using a melt-kneader in advance to achieve a predetermined concentration using polypropylene. It can be used in the form of dilution or melt-kneading all the amounts beforehand.

The wet tension of the surface of the surface layer (B) is preferably 38 mN / m or more.

When the wetting tension is 38 mN / m or more, the adhesion with the printing ink or the adhesive is improved.

The wet tension is more preferably 16 mN / m or more. In order to set the wet tension to 38 mN / m or more, additives such as an antistatic agent or a surfactant are generally used. However, in order to reduce the inherent resistance of the surface, surface treatments such as corona treatment and flame treatment may be mentioned.

For example, the corona treatment is preferably performed in the air using a preheating roller and a processing roller.

In the surface of the surface layer (B) of the biaxially oriented polypropylene-based film of the present invention, the height of the center surface convex portion SRp + the depth of the center surface concave portion SRv is preferably 1.0 μm or more and 2.0 μm or less.

The surface roughness of the surface layer (B) here refers to the height SRp of the center plane convex portion and the depth SRv of the center plane concave portion, using a three-dimensional roughness meter, with a stylus pressure of 20 mg, a measurement length of 1 mm in the X direction, and The feed pitch is 2 μm, the number of recorded lines is 99, the height direction magnification is 20,000 times, and the cut-off value is 80 μm. It is calculated according to the definition of the arithmetic mean roughness described in JIS (Japanese Industrial Standards) B0601 (1994). .

The height of the center surface convex portion SRp + the depth of the center surface concave portion SRv of the surface of the surface layer (B) is an indicator of the state of large uneven portions formed by the lubricant, and in the state of a roll film, and The sliding property when the base material layer (A) is in contact is related.

When the height of the center surface convex portion SRp + the depth of the center surface concave portion SRv of the surface of the surface layer (B) is 1.0 μm or more, the roll-out property of the self-rolling film is improved, and if it is 2.0 μm or less, transparency is maintained.

The center surface convex portion height SRp + center surface concave portion depth SRv of the surface of the surface layer (B) is preferably 1.1 μm or more, more preferably 1.2 μm or more, and even more preferably 1.3 μm or more.

In order to set the center surface convex portion height SRp + center surface concave portion depth SRv of the surface of the surface layer (B) to 1.0 μm or more and 2.0 μm or less, The compounding of the anti-blocking agent in the polypropylene resin composition of the surface layer (B) is a suitable method.

The anti-caking agent may be suitably selected from inorganic anti-caking agents such as silica, zirconium carbonate, kaolin, and zeolite, or organic anti-caking agents such as acrylic, polymethacrylic, and polystyrene. Select and use. Among these anti-caking agents, it is particularly preferable to use silicon dioxide.

The preferred average particle diameter of the anti-caking agent is 1.0 μm to 2.0 μm, and more preferably 1.0 μm to 1.5 μm.

The anti-blocking agent is preferably set to 3000 ppm by mass in the polypropylene resin composition. The measurement method of the average particle diameter described here is a photograph taken with a scanning electron microscope, and a Feret's diameter in a horizontal direction is measured using an image analysis device, and expressed as an average value of the Feret's diameter.

(4) Biaxially oriented polypropylene film

The overall thickness of the biaxially oriented polypropylene film of the present invention is preferably 9 μm to 200 μm, more preferably 10 μm to 150 μm, still more preferably 12 μm to 100 μm, and even more preferably 12 μm to 80 μm.

The thickness ratio of the surface layer (B) to the substrate layer (A) in the biaxially oriented polypropylene film of the second invention is preferably 0.01 to 0.5 for the entire surface layer (B) / the entire substrate layer (A). It is more preferably 0.03 to 0.4, and still more preferably 0.05 to 0.3. When the entire surface layer (B) / the entire base material layer (A) exceeds 0.5, the shrinkage tends to increase. In addition, with respect to the entire thickness of the film The thickness of the substrate layer (A) is preferably 50% to 99%, more preferably 60% to 97%, and even more preferably 70% to 95%. The remaining part becomes the surface layer (B) or the surface layer (B) and other layers (for example, the C layer). The substantial thickness of the entire surface layer (B) is preferably 0.5 μm to 4 μm, more preferably 1 μm to 3.5 μm, and still more preferably 1.5 μm to 3 μm.

As the ratio of the thickness of the surface layer (B) to the substrate layer (A) in the biaxially oriented polypropylene film of the second invention, the entire surface layer (B) / the entire substrate layer (A) is preferably 0.01 to 0.5, more preferably 0.03 to 0.4, and still more preferably 0.05 to 0.3. When the entire surface layer (B) / the entire base material layer (A) exceeds 0.5, the shrinkage tends to increase. In addition, the thickness of the entire substrate layer (A) relative to the thickness of the entire film is preferably 50% to 99%, more preferably 60% to 97%, and even more preferably 70% to 95%. The remaining part becomes the surface layer (B) or the surface layer (B) and other layers (for example, the C layer).

The substantial thickness of the entire surface layer (B) is preferably 0.5 μm to 4 μm, more preferably 1 μm to 3.5 μm, and still more preferably 1.5 μm to 3 μm.

The biaxially oriented polypropylene film of the second invention may be a two-layered film having a base material layer (A) and a surface layer (B) each having one layer, or a structure having three or more layers. A two-layer structure of the substrate layer (A) / surface layer (B) is preferred. In addition, it may have a three-layer structure of a surface layer (B) / A layer / surface layer (B), / base material layer (A) / intermediate layer (C) / surface layer (B), or a multilayer structure of more layers .

When there are a plurality of base material layers (A) or surface layers (B), as long as each layer satisfies the characteristics of the layer, the composition may be different.

(5) Film characteristics

The thermal shrinkage of the biaxially oriented polypropylene film of the present invention at 150 ° C in the longitudinal and transverse directions is preferably 8% or less, more preferably 7% or less, and even more preferably 8% or less. By setting the thermal shrinkage to 8% or less, negative thermal wrinkles during processing can be reduced.

For the biaxially oriented polypropylene film of the present invention, the thermal shrinkage in the machine direction at 150 ° C is preferably 0.2% to 8%, and more preferably 0.3% to 7%. If the heat shrinkage ratio is in the above range, it can be said to be a film excellent in heat resistance, and it can also be used in applications that are likely to be exposed to high temperatures. In addition, if the thermal shrinkage rate at 150 ° C is about 1.5%, it can be achieved by, for example, adding a low molecular weight component, adjusting the elongation conditions, or heat-fixing conditions. However, in order to reduce the temperature to 1.5% or less, it is preferable to perform the annealing offline deal with.

For the biaxially oriented polypropylene film of the present invention, the thermal shrinkage in the transverse direction at 150 ° C is preferably 0.2% to 8%, more preferably 0.3% to 7%, and further preferably 0.4% to 6%, especially It is preferably 0.5% to 5%. When the heat shrinkage ratio is in the above range, it can be said to be a film having particularly excellent heat resistance, and it can also be used for applications that may be exposed to high temperatures. In addition, if the thermal shrinkage rate at 150 ° C is about 1.5%, it can be achieved by, for example, adding a low molecular weight component, adjusting the elongation conditions, or heat-fixing conditions. However, in order to reduce the temperature to 1.5% or less, it is preferable to perform the annealing offline deal with.

The longitudinal elastic modulus of the biaxially oriented polypropylene film of the present invention is preferably 1.8 GPa to 4 GPa, more preferably 2.1 GPa to 3.7 GPa, further preferably 2.2 GPa to 3.5 GPa, and even more preferably 2.3 GPa to 3.4. GPa. The measurement method will be described later.

The transverse elastic modulus of the biaxially oriented polypropylene film of the present invention is preferably 4.5 GPa to 8 GPa, more preferably 4.6 GPa to 7.5 GPa, further preferably 4.7 GPa to 7 GPa, and even more preferably 4.8 GPa to 6.5 GPa. . If the tensile elastic modulus in the transverse direction is within the above range, a film that is not easily bent can be produced.

The degree of resistance to bending of the biaxially oriented polypropylene film of the present invention is that the film is held in a ring shape and compressed, and the ring crush strength measured by using a load cell to detect the compression resistance is evaluated. The measurement 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%, still more preferably 0.3% to 4.5%, and even more preferably 0.4% to 4%. If it is the said range, it may be easy to use for the application which requires transparency. For example, when the elongation temperature and heat fixing temperature are too high, the cooling roll (CR) temperature is high, and the cooling speed of the stretched original fabric sheet is slow. When the low molecular weight component is too much, the haze may be deteriorated. The tendency can be set within the above range by adjusting these conditions. The method of measuring the haze will be described later.

The lower limit of the surface alignment 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. If it is the said range, it will become easy to increase the heat resistance and rigidity of a film.

The stretched laminated polypropylene film usually has a crystal orientation, and the direction or degree of the crystal orientation greatly affects the film physical properties. The degree of crystal orientation tends to change depending on the molecular structure of the polypropylene used, or the process or conditions in the production of the film, and these conditions can be adjusted to fall within the above range. The measurement method will be described later.

About the evaluation of the ink adhesion of the biaxially oriented polypropylene film of the present invention, the peeling test of the printing ink subjected to gravure printing was performed, and the number of peeling portions in the total of 25 places was evaluated. The number of peeling points is preferably 15 or less, more preferably 5 or less, and most preferably 0. If there are 15 or more, the peeling degree of ink becomes large and it becomes a problem. The evaluation method of ink adhesion will be described later.

The lamination strength of the biaxially oriented polypropylene film of the present invention after lamination is preferably 1.2N / 15mm to 2.5N / 15mm, more preferably 1.3N / 15mm to 2.5N / mm, and further preferably 1.4N. / 15mm to 2.5N / mm. The method for measuring the lamination 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 even more preferably 0.45 or less. If the dynamic friction coefficient is 0.5 or less, the film can be unrolled smoothly from the roll-shaped film. Easy to print. The method of measuring the dynamic friction coefficient will be described later.

(4) Manufacturing method

The biaxially stretched laminated polypropylene film of the present invention can be obtained by melt-extruding a polypropylene resin by an extruder to form an unstretched sheet, and extending the unstretched sheet by a predetermined method and Perform heat treatment.

In the case of the second invention, a polypropylene material for the base material layer (A) (polypropylene resin composition for the base material layer (A)) and a polypropylene material for the surface layer (B) can be obtained by using different extruders. The surface layer (B) is separately melt-extruded with a polypropylene-based resin composition to form a laminated unstretched sheet. The unstretched sheet is stretched and heat-treated by a predetermined method, thereby obtaining a biaxially oriented polymer. Acrylic film.

Unstretched sheet is obtained by using multiple extruders or feed blocks, multi-manifolds. The melt extrusion temperature is preferably about 200 ° C to 280 ° C.

In the second invention, in order to obtain a good-looking laminated film without disturbing the layer in the above temperature range, it is preferable that the polypropylene material for the base layer (A) and the polypropylene material for the surface layer (B) have poor viscosity. (MFR difference) is set to 6 g / 10 minutes or less. If the viscosity difference is more than 6 g / 10 minutes, the layer will be turbulent, and the appearance will be easily deteriorated. It is more preferably 5.5 g / 10 minutes or less, and still more preferably 5 g / 10 minutes or less.

The surface temperature of the cooling roll is preferably 25 ° C to 35 ° C, and more preferably 27 ° C to 33 ° C. Then, the film was stretched at a length of 120 ° to 165 ° C using a stretching roller. (MD (Machine Direction)) direction to 3 to 8 times, preferably 3 to 7 times, and then 4 times in the TD direction at 155 ° C to 175 ° C, more preferably 160 ° C to 163 ° C. An extension of 20 times, preferably 6 times to 12 times. Furthermore, heat-fixing is performed while performing a relaxation of 2% to 10% at 165 ° C to 176 ° C, more preferably 170 ° C to 176 ° C, and further preferably 172 ° C to 175 ° C. The biaxially stretched laminated polypropylene film thus obtained is subjected to corona discharge, plasma treatment, flame treatment, etc. as necessary, and then wound up by a winder to obtain a film roll.

The lower limit of the stretch magnification of MD is preferably 3 times, and more preferably 3.5 times. If it is less than the said lower limit, film thickness may become uneven. The upper limit of MD stretching magnification is preferably 8 times, and more preferably 7 times. If the above upper limit is exceeded, the subsequent TD extension may become difficult. The lower limit of MD extension temperature is preferably 120 ° C, more preferably 125 ° C, and even more preferably 130 ° C. If it is less than the said lower limit, a mechanical load may increase, thickness unevenness may become large, or the surface of a film may become rough. The upper limit of MD stretching temperature is preferably 160 ° C, more preferably 155 ° C, and even more preferably 150 ° C. When the temperature is high, it is preferable to reduce the thermal shrinkage. However, it sometimes adheres to the roll and cannot be extended, or causes rough surface.

The lower limit of the extension ratio of TD is preferably 4 times, more preferably 5 times, and even more preferably 6 times. If it is less than the said lower limit, thickness may become uneven. The upper limit of the TD stretching magnification is preferably 20 times, more preferably 17 times, further preferably 15 times, and even more preferably 12 times. If the upper limit is exceeded, the thermal shrinkage rate may change. High, or broken during extension. Regarding the preheating temperature during TD stretching, in order to quickly increase the film temperature to around the stretching temperature, it is preferably set to be 5 ° C to 15 ° C higher than the stretching temperature. TD stretching is performed at a higher temperature than the previous biaxially oriented polypropylene film. The lower limit of the extension temperature of TD is preferably 155 ° C, more preferably 157 ° C, still more preferably 158 ° C, and even more preferably 160 ° C. If it is less than the said lower limit, it may not be fully softened and it may fracture | rupture, or thermal contraction rate may become high. The upper limit of the TD extension temperature is preferably 170 ° C, more preferably 168 ° C, and even more preferably 163 ° C. In order to reduce the thermal shrinkage rate, the temperature is preferably high, but if it exceeds the above upper limit, not only the low-molecular component melts and recrystallizes to reduce the orientation, but also the surface may be rough or the film may be whitened.

The stretched film is heat-fixed. Thermal fixation can be performed at higher temperatures than previous biaxially oriented polypropylene films. The lower limit of the heat-fixing temperature is preferably 165 ° C, and more preferably 166 ° C. If it is less than the said lower limit, thermal contraction rate may become high. In addition, in order to reduce the heat shrinkage rate, a long-term treatment is required, and productivity is poor. The upper limit of the heat-fixing temperature is preferably 176 ° C, and more preferably 175 ° C. When it exceeds the said upper limit, a low molecular component may melt | dissolve and recrystallize, and a surface may become rough or a film may become white.

It is preferable to perform relaxation during heat fixing. The lower limit of relaxation is preferably 2%, more preferably 3%. If it is less than the said lower limit, thermal contraction rate may become high. The upper limit of the slack is preferably 10%, more preferably 8%. When it exceeds the said upper limit, thickness unevenness may become large.

Furthermore, in order to reduce the thermal shrinkage, the film produced by the above steps may be temporarily rolled into a roll shape, 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 lower limit, the effect of annealing may not be obtained. The upper limit of the off-line annealing temperature is preferably 175 ° C, more preferably 174 ° C, and even more preferably 173 ° C. When it exceeds the said upper limit, transparency may fall or thickness unevenness may become large.

The lower limit of the offline annealing time is preferably 0.1 minute, more preferably 0.5 minute, and even more preferably 1 minute. If it is less than the lower limit, 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 even more preferably 20 minutes. When it exceeds the said upper limit, productivity may fall.

[Example]

Hereinafter, the present invention is further described in detail through examples. However, the following examples do not limit the present invention, and changes and implementations without departing from the spirit of the present invention are included in the present invention. The methods for measuring the physical properties of the films obtained in the examples and comparative examples are as follows.

1) Stereo regularity

The measurement of the meso pentad fraction ([mmmm]%) was performed using ¹³ C-NMR. The meso pentad fraction was calculated according to the method described in "Macromolecules" by Zambelli et al., Vol. 6, p. 925 (1973). ^{The 13} C-NMR measurement was performed using "AVANCE500" manufactured by BRUKER Corporation. A 200 mg sample was dissolved at 135 ° C in a 8: 2 (volume ratio) mixture of o-dichlorobenzene and deuterated benzene at 110 ° C. get on.

2) Melt flow rate (MFR; g / 10 minutes)

The measurement was performed in accordance with JIS K7210 at a temperature of 230 ° C and a load of 2.16 kgf.

The resin is used by directly weighing the necessary amount of particles (powder).

The film is cut into a sample of about 5 mm square after cutting out the necessary amount.

3) Molecular weight and molecular weight distribution

The molecular weight and molecular weight distribution are calculated based on monodisperse polystyrene standards using gel permeation chromatography (GPC), and converted into polypropylene values. GPC measurement conditions such as column and solvent are as follows.

Solvent: 1,2,4-trichlorobenzene

Column: TSKgel GMHHR-H (20) HT × 3

Flow: 1.0ml / min

Detector: RI (Refractive Index)

Measurement temperature: 140 ° C

The number average molecular weight (Mn), mass average molecular weight (Mw), and molecular weight distribution are each defined by the following formula by the molecular number (Ni) of the molecular weight (Mi) at each dissolution position of the GPC curve obtained from the molecular weight calibration curve.

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 is not clear, the baseline is set in the range from the highest peak on the high molecular weight side to the lowest position on the lower side of the high molecular weight side.

4) thickness

Regarding the thickness of each of the base material layer (A) and the surface layer (B), a biaxially stretched laminated polypropylene film was fixed with a modified urethane resin, a section of the fixed object was cut out with a microtome, and a differential interference microscope was used. Observe and measure.

5) Thermal shrinkage (%)

The measurement was performed in accordance with JIS Z1712 by the following method. The film was cut into a width of 20 mm and a length of 200 mm in the MD and TD directions, respectively, and was suspended in a hot air oven at 150 ° C for 5 minutes. The length after heating was measured, and the heat shrinkage ratio was calculated | required by the ratio of the contracted length with respect to the original length.

6) Tensile elastic modulus (Young's modulus (unit: GPa))

The Young's modulus of the MD direction and TD direction of the film was measured at 23 ° C in accordance with JIS K7127.

7) Ring compression strength (g)

Using a digital ring compressive strength tester (manufactured by Tester Industry Co., Ltd.), a film sample with a size of 12.7mm × 152mm was prepared, and an attached spacer was set on the sample table according to the thickness of the film sample. Film samples were inserted along the circumference in the TD direction. Compressed at 23 ° C The maximum load when the plate is compressed at a descending speed of 12 mm / min. Is taken as the measured value of ring compression strength.

8) Haze (unit:%)

The measurement was performed in accordance with JIS K7105.

9) Coefficient of dynamic friction

The corona-treated surfaces of the film were overlapped with each other in accordance with JIS K7125, and measured at 23 ° C.

10) Refractive index, surface alignment coefficient

The measurement was performed by JIS K7142-1996 5.1 (Method A) using an Abbe refractometer manufactured by Atago. The refractive index in the MD direction and the TD direction are respectively Nx and Ny, and the refractive index in the thickness direction is Nz. The surface alignment coefficient (ΔP) was obtained as (Nx + Ny) / 2-Nz.

11) Surface roughness

The surface roughness evaluation of the obtained film was performed using a three-dimensional roughness meter (manufactured by Kosaka Research Institute, model ET-30HK) with a stylus pressure of 20 mg, a measurement length of 1 mm in the X direction, a supply speed of 100 μm / sec, and a progress in the Y direction The measurement was performed at a pitch of 2 μm with 99 recording lines, a height direction magnification of 20,000 times, and a cutoff value of 80 μm.

The three-dimensional roughness measurement was carried out three times. The arithmetic average roughness (SRa), the height of the center surface protrusion (SRp), and the depth of the center surface depression (SRv) and evaluated based on the average of the measured values.

12) Surface inherent resistance (LogΩ)

After the film was aged at 23 ° C for 24 hours in accordance with JIS K6911, the corona-treated surface of the film was measured.

13) Wet tension (mN / m)

After the film was aged at 23 ° C and 50% relative humidity for 24 hours in accordance with JIS K6768: 1999, the corona-treated surface of the film was measured in the following procedure.

1) The measurement was performed in a standard laboratory atmosphere (refer to JIS K7100) at a temperature of 23 ° C and a relative humidity of 50%.

2) The test piece is placed on the substrate of a manual coater (4.1), and a few drops of the test mixture are dropped on the test piece, and the wire rod is immediately pulled to expand.

When a test liquid is spread using a cotton swab or a brush, the liquid rapidly spreads to an area of at least 6 cm ² . The amount of liquid is set to such an extent that no accumulation occurs and a thin layer is formed.

Regarding the determination of the wet tension, the liquid film of the test mixed liquid was observed in a bright place, and the state of the liquid film after 3 seconds was determined. The liquid film was not damaged, and the state at the time of application was maintained for 3 seconds or more. In the case where wetting is maintained for more than 3 seconds, the mixture is further advanced to a mixed solution under a high surface tension, and when the liquid film is damaged under 3 seconds, it is advanced to a mixed solution under a low surface tension.

Repeat this operation to select a mixture that accurately wets the surface of the test piece for 3 seconds.

3) A new cotton swab was used in each test. The composition and surface tension of the brush or wire rod are changed due to the evaporation of the remaining liquid, so each time it is used, it is washed with methanol and dried.

4) The operation of selecting a mixed solution capable of moistening the surface of the test piece within 3 seconds is performed at least 3 times. The surface tension of the mixture thus selected was reported as the wet tension of the film.

14) Ink adhesion

A gravure printing machine (manufactured by Mitsubu Steel Works Co., Ltd.) was used to perform full gravure printing (printing ink amount: 2 g / m ² ) on the film at a speed of 50 m / min. The ink at this time is a water-based ink (manufactured by Dainippon Ink Chemical Industries, Ltd .: trade name Ecofine709 white). Using this printed sample, evaluation was performed by grid peeling (2 mm grid × 25 pieces, using a 90 ° peeling method of Sellotape (registered trademark) manufactured by Nichiban Co., Ltd. with a width of 18 mm). The following classification was performed.

Mesh stripping part 0. ． ． ：: Excellent adhesion of printing ink.

Grid peeling part 1 to 5. ． ． ○: Printing ink has good adhesion.

6 to 15 grid stripped parts. ． ． △: Printing ink has poor adhesion.

More than 15 grid stripped parts. ． ． ． ×: There is no adhesion of printing ink.

15) Lamination strength

The lamination strength was measured by the following procedure.

1) Production of laminated film with sealing film

Production was performed using a continuous dry laminator as follows.

The corona surfaces of the biaxially oriented polypropylene films obtained in the examples and comparative examples were gravure-coated with an adhesive so that the coating amount became 3.0 g / m ² when dried, and then introduced into a drying zone at 80 ° C., Dry for 5 seconds. Then, it was bonded to the sealing film between the rollers provided on the downstream side (roller pressure: 0.2MP, roller temperature: 60 ° C). The obtained laminated film was subjected to aging treatment at 40 ° C. for 3 days in a rolled state.

In addition, the adhesive was obtained by mixing 17.9% by mass of a main agent (TM329 manufactured by Toyo Morton Co., Ltd.), 17.9% by mass of a hardener (CAT8B manufactured by Toyo Morton Co., Ltd.) and 64.2% by mass of ethyl acetate. For the ether-based adhesive and the sealing film, a biaxially-oriented polypropylene film (Pylen (registered trademark) CT P1128, thickness 30 μm) manufactured by Toyobo Co., Ltd. was used.

2) Determination of lamination strength

The laminated film obtained above was cut out in a short strip shape (length 200 mm, width 15 mm) with long sides in the longitudinal direction of the biaxially oriented polypropylene film, and a tensile tester (Tensilon, manufactured by Oriental Co., Ltd.) was used at 23 ° C. T-peeling was performed at a stretching speed of 200 mm / min under an environment, and the peeling strength (N / 15 mm) at this time was measured. The measurement was performed three times, and the average of the three measurements was taken as the lamination strength.

(Example 1)

99% by weight of polypropylene homopolymers PP-1 and 1 shown in Table 1 A mixture of an antistatic agent (stearyl diethanolamine stearate (KYM-4K of Matsumoto Oil & Fat Co., Ltd.)) by weight%.

A 60 mm extruder was used for this mixture, and the raw resin was melted at 250 ° C, co-extruded in sheet form from a T die, cooled and solidified by a cooling roll at 30 ° C, and then longitudinally (MD) at 135 ° C. Extends to 4.5 times. Then, clamp both ends of the film width direction in a tenter in a tenter, and after preheating at 175 ° C, it stretched 8.2 times in the width direction (TD) at 160 ° C and relaxed 6.7% in the width direction (TD). , Heat-fixed at 170 ° C on one side. The film forming conditions at this time are shown in Table 2 as film forming conditions a.

A corona treatment machine manufactured by Softal Corona And Plasma Gmbh was used to corona treat the unilateral surface side of the obtained biaxially oriented polypropylene film under the condition of applying a current value of 0.75A, and then coiled by a coiler. The obtained roll was used as the biaxially stretched single-layer polypropylene film of the present invention. The physical properties of the obtained film are shown in Table 3.

(Example 2)

The polypropylene homopolymer PP-1 shown in Table 1 was changed to a polypropylene resin PP-2, and the mixed raw materials were melted at 250 ° C. using a 60 mm extruder, and co-extruded in a sheet form from a T die. The cooling roller at 30 ° C was cooled and solidified, and then stretched to a longitudinal direction (MD) to 4.5 times at 125 ° C. Then, the two ends of the film in the width direction were clamped in a tenter in a tenter, and after being preheated at 170 ° C, it was extended to 8.2 times in the width direction (TD) at 158 ° C and relaxed 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-fixed at 165 ° C. Filming at this time The conditions are shown in Table 2 as the film formation conditions b. The physical properties of the obtained film are shown in Table 3.

(Example 3)

For the base material layer (A), 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 oils and fats) KYM-4K)). For the surface layer (B), 99.7 wt% of the polypropylene homopolymer PP-1 shown in Table 1 and 0.3% by mass of an anti-caking agent (commercially available silica particles (average particle diameter: 1.3) were used. μm)).

The mixed raw material for the substrate layer (A) is a 60 mm extruder, and the mixed raw material for the surface layer (B) is a 65 mm extruder. The raw material resins are melted at 250 ° C, respectively, from the T die. Co-extruded in sheet form, cooled and solidified with a cooling roller at 30 ° C, and then stretched to 4.5 times in the machine direction (MD) at 135 ° C. Then, the two ends of the film in the width direction were clamped in a tenter in a tenter, and after preheating at 175 ° C, it was extended to 8.2 times in the width direction (TD) at 160 ° C and relaxed 6.7% in the width direction (TD) One side was heat-fixed at 170 ° C. The film was formed under the film forming conditions a shown in Table 2 and taken up by a winder to obtain a biaxially oriented laminated polypropylene film of the present invention obtained by laminating each of the base material layer (A) and the surface layer (B). . A corona treatment machine manufactured by Softal Corona And Plasma Gmbh was used to corona-treat the surface side of the surface layer (B) of the obtained biaxially oriented polypropylene film under a condition of applying a current value of 0.75 A, and then used for winding. It was taken up by a machine, and the obtained roll was used as the biaxially stretched single-layer polypropylene film of the present invention. Of the resulting film The physical properties are shown in Table 3.

(Example 4)

A biaxially stretched laminated polypropylene film was obtained in the same manner as in Example 3 except that the antistatic agent was not included in the raw material used for the base material layer (A). The physical properties of the obtained film are shown in Table 3.

(Example 5)

For the base material layer (A), 99% by mass of the polypropylene homopolymer PP-1 shown in Table 1 and 1% by mass of an antistatic agent (stearyl diethanolamine stearate (Matsumoto Oils and Fats) KYM-4K)). In addition, for the surface layer (B), the following formulations were used. The formulations were obtained by copolymerizing 48.7 wt% of the polypropylene homopolymer PP-6 shown in Table 1 and 51 wt% of the ethylene copolymer shown in Table 1. A composition obtained by mixing propylene polymer PP-7 and 0.3% by mass of commercially available silica particles (average particle size: 1.3 μm) as an anti-caking agent is formulated, A biaxially oriented laminated polypropylene film was obtained in the same manner as in Example 3.

(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. The physical properties of the obtained film are shown in Table 3.

(Example 7)

A film was obtained in the same manner as in Example 1 except that the film thickness was set to 40 μm. A biaxially stretched monolayer polypropylene film was obtained. The physical properties of the obtained film are shown in Table 3.

(Comparative example 1)

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-3 shown in Table 1. The physical properties of the obtained film are shown in Table 4.

(Comparative example 2)

Except that the polypropylene resin PP-1 shown in Table 1 was changed to the polypropylene resin PP-4 shown in Table 1, a biaxially stretched single-layer polypropylene film was formed in the same manner as in Example 1. Sometimes it breaks and the film cannot be obtained.

(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 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. The raw resin was melted at 250 ° C using a 60 mm extruder and co-extruded in sheet form from a T die. After cooling and solidification using a cooling roller at 30 ° C, it was extended to 4.5 times in the longitudinal direction (MD) at 125 ° C. Then, the two ends in the width direction of the film were clamped in a tenter in a tenter, and after preheating at 170 ° C, one side was extended to 8.2 times in the width direction (TD) at 158 ° C. A biaxially stretched single-layer polypropylene film was obtained in the same manner as in Example 1 except that the width direction (TD) was relaxed by 6.7% and heat-fixed at 165 ° C. The physical properties of the obtained film are 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. The raw resin was melted at 250 ° C using a 60 mm extruder and co-extruded in sheet form from a T die. After cooling and solidification using a cooling roller at 30 ° C, it was stretched in the longitudinal direction (MD) to 4.5 times at 140 ° C. Then, the two ends of the film in the width direction were clamped in a tenter in a tenter, and after being preheated at 170 ° C, it was extended to 8.2 times in the width direction (TD) at 160 ° C and relaxed 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-fixed at 168 ° C. The film forming conditions at this time are shown in Table 2 as film forming conditions c. The physical properties of the obtained film are 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. The raw resin was melted at 250 ° C using a 60 mm extruder and co-extruded in sheet form from a T die. After cooling and solidification using a cooling roller at 30 ° C, it was stretched to 4.5 times in the machine direction (MD) at 135 ° C. Then, the two ends of the film in the width direction were clamped in a tenter in a tenter, and after being preheated at 170 ° C, it was extended to 8.2 times in the width direction (TD) at 160 ° C and relaxed 6.7% in the width direction (TD). One side is thermally fixed at 168 ° C, divided by A biaxially stretched single-layer polypropylene film was obtained in the same manner as in Example 1. The film-forming conditions at this time are shown in Table 2 as film-forming conditions d. The physical properties of the obtained film are shown in Table 4.

[Table 2]

The biaxially oriented polypropylene film obtained in Examples 1 to 5 has a small thermal shrinkage rate and a large Young's modulus. Among them, the laminated films obtained in Examples 3 to 5 further became films having good lamination strength and ink adhesion.

On the other hand, the thermal shrinkage rate of the film width direction (TD) obtained in Comparative Example 1 was large. 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 was a film having a large thermal shrinkage in the width direction (TD) and the machine direction (MD) and a small Young's modulus.

The Young's modulus of the film width direction (TD) obtained in Comparative Example 5 was small. The film obtained in Comparative Example 6 had a large thermal contraction rate in the width direction (TD).

[Industrial availability]

The biaxially stretched laminated polypropylene film of the present invention has higher heat resistance and rigidity, negative heat wrinkles become smaller, and it is difficult to bend, so it has excellent processability.

The biaxially oriented polypropylene film of the present invention can of course be used for food packaging used in a standing pouch and the like, and can also be used for labeling and the like.

Claims (5)

A biaxially oriented polypropylene film. The polypropylene resin constituting the film satisfies the following conditions 1) to 4), and the lower limit of the surface orientation coefficient of the film is 0.0125; 1) The lower limit of the meso pentad component ratio is 96%; 2) the upper limit of the amount of comonomers other than propylene is 0.1 mole%; 3) the mass average molecular weight (Mw) / number average molecular weight (Mn) is 3.0 or more and 5.4 or less; 4) at 230 ° C, 2.16kgf The measured melt flow rate is 6.5 g / 10 minutes or more and 9.0 g / 10 minutes or less. A biaxially oriented polypropylene film having a base material layer (A) containing a polypropylene resin as a main component and a surface layer (B) containing a polypropylene resin as a main component on at least one surface of the base material layer (A) ), And the polypropylene resin constituting the base material layer (A) satisfies the following conditions 1) to 4), and the lower limit of the surface orientation coefficient of the film is 0.0125; 1) the lower limit of the meso pentad component ratio is 96 %; 2) The upper limit of the amount of comonomers other than propylene is 0.1 mole%; 3) Mass average molecular weight (Mw) / number average molecular weight (Mn) is 3.0 or more and 5.4 or less; 4) Measured at 230 ° C and 2.16kgf The melt flow rate is 6.2 g / 10 minutes or more and 9.0 g / 10 minutes or less. Biaxially oriented polypropylene film as described in claim 1 or 2, wherein the film The thermal shrinkage at 150 ° C in the longitudinal and transverse directions is 8% or less. The biaxially oriented polypropylene film according to claim 1 or 2, wherein the tensile elastic modulus of the film in the longitudinal direction is 2.0 GPa or more, and the tensile elastic modulus of the film in the transverse direction is 4.5 GPa or more. The biaxially oriented polypropylene film according to claim 1 or 2, wherein the haze value of the film is 5% or less.