TW201801927A - Biaxially stretched laminated polypropylene film - Google Patents

Abstract

Provided is a biaxially stretched laminated polypropylene film having high rigidity, excellent thermal resistance, and excellent antistatic properties. This biaxially stretched laminated polypropylene film includes at least two layers of polypropylene-based resin compositions having different crystallinity and is characterized by: having an A layer comprising a polypropylene-based resin composition having a melting endothermic peak area [Delta]H of at least 78.0 J/g and a B layer comprising a polypropylene-based resin composition having a [Delta]H of less than 82.0 J/g and having a [Delta]H that is 2.0-40.0 J/g lower than the [Delta]H of the A layer, when the melting endothermic peak area [Delta]H is measured using a differential scanning calorimeter and at a heating rate of 20 DEG C/min; and the B layer being present on at least one outermost surface side.

Description

Biaxially stretched laminated polypropylene film

The invention relates to a biaxially stretched laminated polypropylene film. Specifically, the present invention relates to a biaxially stretched polypropylene film having excellent heat resistance, rigidity, and excellent antistatic 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 of the present case conducted hard research based on the above-mentioned prior art, and as a result, successfully achieved the following: by using ¹³ C-NMR (Nuclear Magnetic Resonance; nuclear magnetic resonance) as an indicator of the stereoregularity of the polypropylene resin constituting the film Resonance) is a polypropylene-based polymer having a meso pentad ratio of 96% or more, and provides a stretched polypropylene film with high rigidity and high heat resistance (Patent Document 2).

[Prior technical literature] [Patent Literature]

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

Patent Document 2: WO2015 / 012324.

However, there is room for improvement in antistatic properties in the aforementioned Patent Document 2.

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

The constitution of the present invention is as follows.

1. A biaxially stretched laminated polypropylene film, which is a laminated film containing at least two or more layers of polypropylene-based resin compositions having different crystallinity, characterized in that: The reason is that when the melting endothermic peak area measured using a differential scanning calorimeter at a heating rate of 20 ° C / min is set to △ H, it has: A layer, which is a polypropylene resin composition with △ H of 78.0J / g or more And B layer, which is composed of a polypropylene-based resin composition having a ΔH of less than 82.0 J / g and a ΔH that is 2.0 J / g to 40.0 J / g lower than the ΔH of the A layer; the aforementioned B The layer system is present on at least one of the outermost sides.

2. The biaxially stretched laminated polypropylene film according to the above 1, wherein the ratio of the total thickness of the aforementioned B layer to the total thickness of the aforementioned A layer (the entire B layer / the entire A layer) is 0.01 to 0.5, and the aforementioned B The total thickness of the layers is 0.5 μm to 4 μm.

3. The biaxially stretched laminated polypropylene film according to 1 or 2 above, further comprising a polypropylene resin having a thickness of 0.01 μm to 1.0 μm and a ΔH exceeding 76.0 J / g on the outermost surface side of the B layer. The other layers of the composition.

4. The biaxially stretched laminated polypropylene film according to any one of 1 to 3 above, wherein the MFR (Melt Flow Rate; Melt Flow Rate) of the entire film is from 2.0 g / 10 minutes to 10.5 g / 10 minutes.

5. The biaxially stretched laminated polypropylene film according to any one of 1 to 4 above, wherein the surface inherent resistance value (LogΩ) of the entire film is 13.5 or less.

6. The biaxially stretched laminated polypropylene film according to any one of 1 to 5 above, wherein the dynamic friction coefficient of the entire film is 0.4 or less.

7. The biaxially stretched laminated polypropylene film according to any one of 1 to 6 above, wherein the thermal shrinkage at 150 ° C is in MD (Machine Direction (longitudinal) direction and TD (Transverse Direction) direction are both below 10.0%, the tensile elastic modulus in MD direction is above 2.0 GPa, and the tensile elastic modulus in TD direction is above 3.8 GPa.

8. The biaxially stretched laminated polypropylene film according to any one of 1 to 7 above, wherein the lamination strength in the MD direction after lamination is 1.2N / 15mm or more.

The polypropylene film of the present invention has at least two layers of a layer A with high crystallinity and a layer B with low crystallinity, and has a laminated structure in which the layer B is arranged on the outermost side, so the antistatic agent mixed into at least one layer The surface of the layer B of low crystallinity arranged on the outermost surface gradually bleeded out. As a result, good antistatic properties can be exhibited while maintaining the excellent heat resistance or rigidity of the layer A having high crystallinity.

The polypropylene film of the present invention is a biaxially stretched laminated polypropylene film, which contains at least two or more layers of polypropylene resin compositions having different crystallinity, and is characterized in that DSC ((Differential Scanning Calorimeter; differential scanning) Calorimeter) When the melting endothermic peak area (total melting heat) measured at a heating rate of 20 ° C / min is set to △ H, it has: A layer, made of polypropylene resin composition with △ H of 78.0J / g or more Constitute The B layer is composed of a polypropylene-based resin composition having a ΔH of less than 82.0 J / g and a △ H lower than the ΔH of the A layer by 2.0 J / g to 40.0 J / g; and the B layer is Exist on at least one of the outermost sides.

Here, the above-mentioned ΔH is a value that serves as an index of crystallinity. The higher the crystallinity, the greater the energy required for the crystal to melt. Therefore, the larger ΔH, the higher the crystallinity. In the present invention, ΔH is determined by measuring a DSC curve of each raw material used for film production at a temperature increase rate of 20 ° C./minute.

First, ΔH of the most characteristic layer A and layer B of the present invention will be described.

Layer A is a layer that bears high crystallinity such as heat resistance, rigidity, and mechanical strength after lamination. Therefore, △ H must be 78.0J / g or more, more preferably 80.0J / g or more, and even more preferably 81.0J / g. The above is further 82.0 J / g or more. When the ΔH of the layer A is small, the rigidity such as the tensile elastic modulus becomes small, which is not preferable. The ΔH of the layer A is preferably 104.0 J / g or less, more preferably 102.0 J / g or less, and even more preferably 100.0 J / g or less. If the ΔH of the layer A is too large, it may require high temperature and long-term manufacturing, which may actually make it difficult in industrial manufacturing.

On the other hand, layer B is a layer with low crystallinity located on the outermost surface side than layer A, and has the following functions: It is natural to make the antistatic agent mixed into the layer B (surface layer) with low crystallinity on the surface side. The surface of layer B oozes, and the antistatic agent kneaded into layer A (core layer) with high crystallinity oozes on the surface of layer B on the outermost side, and imparts excellent antistatic properties. Therefore, △ H of layer B It must be less than 82.0 J / g and have a ΔH that is 2.0 J / g to 40.0 J / g lower than the ΔH of the A layer. When the ΔH of the B layer is 82.0 J / g or more, the amount of antistatic agent bleed out becomes small, and the antistatic property becomes insufficient. In addition, the film tends to have poor lubricity, and there is a possibility that the film cannot be formed stably. Furthermore, the lamination strength described below may be reduced. The △ H of the B layer is preferably 81.0 J / g or less, more preferably 80.0 J / g or less, and even more preferably less than 78.0 J / g. The lower limit of ΔH of the layer B is not particularly limited, and ΔH is preferably 60.0 J / g or more. When ΔH is less than 60.0 J / g, the tensile modulus of elasticity may decrease, or the heat shrinkage ratio may increase, or the transparency may decrease, or it may adhere to a roll.

In addition, the difference between ΔH of layer A and ΔH of layer B (ΔH of layer A-ΔH of layer B) is 2.0 J / g to 40.0 J / g. If the difference is less than 2.0 J / g, the high-crystalline layer and the low-crystalline layer may be laminated to achieve the desired coexistence of heat resistance and antistatic properties, resulting in insufficient effects. On the other hand, if the difference is more than 40.0 J / g, there is a problem that the low-crystalline layer is negatively heated and whitened due to the heat during stretching. The preferable range of the difference of ΔH is 3.0 J / g to 25 J / g, and more preferably 4.0 J / g to 15 J / g.

In the biaxially stretched laminated polypropylene film of the present invention, in order to increase the crystallinity (△ H) of the polypropylene resin of layer A, there are the following methods: reducing the molecular weight of layer A; reducing the copolymerization monomer in the polypropylene resin Increase the ratio of the meso pentad component as an index of the three-dimensional regularity of the resin; increase the amount of low-molecular-weight components with a molecular weight of about 100,000 or less, and the like. The reason for this method is that low molecular weight components with a molecular weight of about 100,000 or less accelerate the formation of The effect of crystallization speed is large. In addition, high molecular weight components with a molecular weight of about 1 million or more function as crystallization nucleating agents and promote the crystallization rate of low molecular weight components. Therefore, the low molecular weight components are mixed with a small amount of high molecular weight components to increase the molecular weight distribution ( Mw / Mn) is also an effective method.

On the other hand, in order to reduce the crystallinity (△ H) of the polypropylene resin of the B layer, there are the following methods: increasing the molecular weight of the B layer; increasing the copolymerization component in the polypropylene resin; reducing the meso pentad Composition rate and so on.

The laminated film of the present invention has characteristics in defining the ΔH (total melting heat) of the A layer, the ΔH of the B layer, and the difference between the ΔH as described above, but the melting endothermic peak temperature in the DSC curve also becomes crystalline A standard of sex. The melting endothermic peak temperature of the layer A is preferably 160 ° C or more, and more preferably 163 ° C or more. The temperature is preferably 176 ° C or lower, more preferably 173 ° C or lower, and even more preferably 170 ° C or lower.

On the other hand, in the case of layer B, the melting endothermic peak temperature is preferably 166 ° C or lower, and more preferably 164 ° C or lower. The temperature is preferably 120 ° C or higher, and more preferably 130 ° C or higher.

Hereinafter, the A layer and the B layer constituting the laminated film of the present invention will be described in more detail.

(Layer A)

As the polypropylene resin used in the layer A of the present invention, not only a polypropylene homopolymer, but also a polypropylene copolymerized with ethylene and / or an α-olefin having a carbon number of 4 or more at 0.5 mol% or less may be used. Such copolymerized polypropylene is also included in the polypropylene-based resin of the present invention (hereinafter sometimes referred to simply as polypropylene). Examples of the α-olefin having 4 or more carbon atoms include 1-butene, 1-hexene, 4-methyl-1-pentene, and 1-octene. In the case of the layer A, it is preferable to reduce the copolymerizable monomer in the polypropylene resin and increase ΔH as described above. Therefore, the ethylene or the α-olefin having 4 or more carbon atoms and other copolymerization components are preferably 0.3 Molar% or less, more preferably 0.1 Molar% or less, and most preferably a completely homopolypropylene (polypropylene homopolymer) without a copolymerization component. When more than 0.5 mol% of ethylene and / or an α-olefin having a carbon number of 4 or more are copolymerized, ΔH may decrease, crystallinity or rigidity may decrease too much, and the thermal shrinkage at high temperatures may increase. In addition, a resin (for example, completely homopolypropylene and copolymerized polypropylene) that satisfies the above conditions may be blended and used.

The meso pentad fraction ([mmmm]%) measured by ¹³ C-NMR as an index of stereoregularity of the polypropylene constituting the A layer of the present invention is preferably 98% to 99.5%. It is more preferably 98.1% or more, and still more preferably 98.2% or more. If the meso-pentad rate of the polypropylene of the A layer 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 mass average molecular weight (Mw) of the polypropylene constituting the A layer of the present invention is preferably 180,000 to 500,000. If it is less than 180,000, the melt viscosity is low, and therefore it may be unstable during casting and the film forming properties may be deteriorated. If Mw exceeds 500,000, it may be difficult to extrude and the film forming property is poor, so it is not good. In addition, if Mw is high, the amount of low-molecular-weight components having a molecular weight of 100,000 or less in the cumulative curve of GPC (Gel Permeation Chromatography) may decrease and the heat shrinkage rate may increase. A more preferable lower limit of Mw is 190,000, and further preferably 200,000, and a more preferable upper limit of Mw is 450,000, further preferably 420,000, and even more preferably 410,000.

Furthermore, in order to easily obtain the required low thermal shrinkage at high temperatures or reduce thickness unevenness, it is preferable to set the content ratio of the low molecular weight component in the A layer to 35% by weight or more, more preferably 38% by weight or more, more preferably 42% by weight or more.

The number average molecular weight (Mn) of the polypropylene constituting the A layer of the present invention is preferably 20,000 to 200,000. If it is less than 20,000, the melt viscosity is low, and therefore it may be unstable during casting and the film forming properties may be deteriorated. If it exceeds 200,000, it may become difficult to extrude and the film forming property may be inferior, which is not preferable. Moreover, when Mn is high, the thermal shrinkage rate may become high. 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 170,000, further preferably 160,000, and even more preferably 150,000.

The Mw / Mn as an index of the molecular weight distribution is preferably 2.8 to 30 for the polypropylene of the A layer. More preferably, it is 3 to 15, more preferably 3.2 to 10, and even more preferably 3.5 to 6.

Here, Mw / Mn can be increased by mixing a low molecular weight component with a small amount of a high molecular weight component as described above. That is, the molecular weight is about 100,000 The following low-molecular-weight components have a large effect of accelerating the crystallization rate. However, when a high-molecular-weight component having a molecular weight of about 1 million or more is added, it functions as a crystal nucleating agent to promote the addition of low-molecular-weight components. When a low molecular weight component is mixed with a small amount of a high molecular weight component, Mw / Mn increases. When there are many low-molecular-weight components, the intertwining of molecules becomes strong, and even if the crystallinity is high, the thermal shrinkage rate tends to increase. If Mw / Mn becomes too large, there may be a case where the number of high molecular weight components increases and the heat shrinkage ratio increases, which is not preferable. At this time, Mw / Mn is preferably 8 to 30, and more preferably 8 to 15. The MFR at this time is preferably 2 g / 10 minutes to 6 g / 10 minutes.

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

The melt flow rate (MFR; 230 ° C, 2.16 kgf) of the polypropylene of the layer A is preferably 0.5 g / 10 minutes to 20 g / 10 minutes. The lower limit of MFR is more preferably 2 g / 10 minutes, further preferably 4 g / 10 minutes, even more preferably 5 g / 10 minutes, and most preferably 6 g / 10 minutes. The upper limit of the MFR of the polypropylene of the layer A is more preferably 15 g / 10 minutes, further preferably 12 g / 10 minutes, particularly preferably 10 g / 10 minutes, and most preferably 9.5 g / 10 minutes. If it is this range, the adhesiveness to a cooling roll will also be good, and film forming property will be excellent, and the heat shrinkage rate which can maintain high temperature is also small.

(Layer B)

As the polypropylene resin used in the layer B of the present invention, not only a polypropylene homopolymer but also a polypropylene copolymerized with ethylene and / or an α-olefin having 4 or more carbon atoms can 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. In the case of the B layer, the total amount of ethylene or an α-olefin having 4 or more carbon atoms (hereinafter sometimes referred to as a copolymerization component) is preferably 8.0 mol% or less, and more preferably 6.0 mol% or less. . 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. In addition, a resin (for example, completely homopolypropylene and copolymerized polypropylene) that satisfies the above conditions may be blended and used. In the case of blending, each resin may also be copolymerized in excess of 8.0 mol%. The blend is preferably based on monomer units and monomers other than propylene are 8.0 mol% or less.

In addition, the polypropylene of the layer B of the present invention preferably has an MFR of 0.5 g / 10 minutes to 10 g / 10 minutes. The lower limit of the MFR of the polypropylene of the 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 of the layer B is more preferably 8 g / 10 minutes, and further preferably 5.5 g / 10 minutes. If it is in this range, the film forming property is also good, and the thermal shrinkage rate at a high temperature can be kept small. In contrast, if the MFR of the polypropylene of the B layer is less than 0.5 g / 10 minutes, when the MFR of the polypropylene of the A layer is large, the viscosity difference between the A layer and the B layer increases, so it is easy to make the film. Unevenness (formerly uneven). If the MFR of layer B exceeds 10g / 10 minutes, the adhesiveness to the cooling roller will change. Poor, smoothness is caused by being entrained in air, and there are many disadvantages that the air becomes a starting point.

The meso-pentad rate of the polypropylene in the B layer is preferably 98.2% or less. It is more preferably 98.0% or less, and still more preferably 97.8% or less. If the meso-pentad rate of the polypropylene of the B layer is large, the crystallinity becomes too high, it is difficult to cause the antistatic agent to bleed out, and the antistatic property may be reduced. In addition, lubricity and lamination strength tend to decrease. In addition, from the above viewpoint, the meso-pentad rate of the polypropylene of the layer B is not particularly limited, but it is preferably 90% or more in consideration of film appearance, film forming properties, and the like.

The mass average molecular weight (Mw) of the polypropylene constituting the B layer of the present invention is preferably 200,000 to 500,000. If it is less than 200,000, the adhesiveness to a cooling roll may worsen, and air may be drawn in and it may be inferior in smoothness, and there exists a possibility that this air may become a starting point, and there are many disadvantages. If Mw exceeds 500,000, extrusion may become difficult, and unevenness (original fabric unevenness) is likely to occur during film formation, which is not preferable. A more preferable lower limit of Mw is 220,000, and further preferably 240,000, and a more preferable upper limit of Mw is 450,000, further preferably 420,000, and even more preferably 410,000.

The number average molecular weight (Mn) of the polypropylene constituting the B layer of the present invention is preferably 50,000 to 200,000. If it is less than 50,000, the melt viscosity is low, it is unstable at the time of casting, the adhesiveness to the cooling roll is poor, and the air is entrained to have poor smoothness, and the shortcoming of this air as a starting point may increase. If it exceeds 200,000, it may become difficult to extrude and the film forming property may be inferior, which is not preferable. more The lower limit of Mn is preferably 60,000, and further preferably 70,000, and the upper limit of Mn is more preferably 170,000, further preferably 160,000, and particularly preferably 150,000.

In the B layer, Mw / Mn is preferably 3.5 to 30, more preferably 3.7 to 20, and even more preferably 3.7 to 15.

(Laminated film)

The biaxially stretched laminated polypropylene film of the present invention includes the aforementioned A layer and B layer, and is arranged such that the B layer becomes at least one outermost surface side. The "layer B exists on at least one of the outermost surfaces" herein means that the layer B is closer to the layer A than viewed from at least one side. In addition, the "most surface side" refers to the relationship between the A layer and the B layer constituting the laminated film. The B layer is located on the outermost surface than the A layer, except that the B layer is arranged on the outermost surface (top) of the laminated film. In addition to the situation, it also includes the spirit of placing other layers (except A layer and B layer) on the top surface (top). That is, the laminated film of the present invention can have not only two layers but also a multilayer structure of three or more layers.

Specifically, in the case where the laminated film of the present invention is composed of only the above-mentioned A layer and B layer as a resin component, it may be an A layer (core layer) and a B layer (surface layer) each having one layer (that is, A layer Two layers of two-layer structure film on one side of the layer, or B layer on both sides of layer A (core layer) as the two surface layers (that is, layer B on both sides of layer A) Sandwich structure of two types and three layers (B layer / A layer / B layer). Or it can be, for example, two kinds of five layers The structure (layer B / A layer / B layer / A layer / B layer) can also be a multilayer structure with more layers. Of course, it is not limited to these structures, and it can have various aspects, such as layer A, layer A, layer B, layer A, layer B, and layer B, as the outermost surface side. Among these structures, two types of three-layer structures of B layer / A layer / B layer are preferred. Furthermore, when the laminated film has a plurality of A layers and B layers, each layer may be the same type of resin or the types may be different.

Alternatively, the biaxially stretched laminated polypropylene film of the present invention may further include other polypropylene-based resin layers other than the A layer and the B layer (for convenience, the layers other than the above are collectively referred to as the C layer). By using such a C layer as the outermost layer, the antistatic agent does not substantially prevent the bleeding of the antistatic agent, and the heat resistance of the outermost layer can be further ensured. Here, the C layer system ΔH exceeds 76.0 J / g and is not classified into any of the above-mentioned A layer and B layer. The C layer can be arranged at any position. It can be arranged between the A layer and the B layer, which is closer to the core side than the A layer and to the outermost side than the B layer. The C layer is preferably disposed closer to the outermost surface than the B layer. For example, the C layer may be a three-layer film having three layers of the C layer, the B layer, and the A layer in order from the outermost surface side. Furthermore, as the raw materials used in the layer C, the raw materials described in the layers A and B can be appropriately used. For example, as the polypropylene-based resin composition of the C layer, the polypropylene-based resin composition used in the A-layer may be used, or a different polypropylene-based resin composition may be used.

The thickness of the entire film 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.

As a ratio of the thicknesses of the B layer and the A layer, the entire B layer (the total thickness of the B layers in the case of plural B layers) / the entire A layer (these A in the case of plural A layers) are preferable The total thickness of the layers) is 0.01 to 0.5, more preferably 0.03 to 0.4, and even more preferably 0.05 to 0.3. When the entire B layer / the entire A layer exceeds 0.5, the elastic modulus tends to decrease. In addition, the thickness of the entire A layer with respect 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 remainder becomes layer B or layer C and layer C other than layer B.

The substantial thickness of the entire layer A is preferably 5 μm to 50 μm, more preferably 10 μm to 45 μm, and still more preferably 15 μm to 40 μm.

In addition, the substantial thickness of the entire layer B is preferably 0.1 μm or more, more preferably 0.5 μm or more, further preferably 1 μm or more, and even more preferably 1.5 μm or more; preferably 4 μm or less, and more preferably 3.5 μm or less It is more preferably 3 μm or less, and still more preferably 2 μm or less.

When the C layer is further present, the thickness of the C layer is preferably 0.01 μm to 1.0 μm, preferably 0.05 μm or more, and more preferably 0.1 μm or more. The thickness of the C layer is preferably thinner than the aforementioned B layer, and is preferably less than 0.5 μm.

The MFR of the entire film is preferably 2.0 g / 10 minutes to 10.5 g / 10 minutes. If it is less than 2.0 g / 10 minutes, the film forming property is inferior, and the thermal shrinkage of the obtained film tends to be large. A more preferable lower limit of MFR is 3.0 g / 10 minutes. another On the other hand, when it exceeds 10.5 g / 10 minutes, the adhesiveness to a cooling roll will fall, the film forming stability will be inferior, and the defect, such as a foreign material, will tend to increase.

The polypropylene 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 performing polymerization in a gas phase state; or a method of combining these methods to perform polymerization, and the like.

The biaxially stretched laminated polypropylene film of the present invention contains an antistatic agent. The content of the antistatic agent contained in the entire film is preferably 0.01% by mass to 3.0% by mass, more preferably 0.05% by mass to 2.8% by mass, and still more preferably 0.10% by mass to 2.5% by mass. The antistatic agent is not particularly limited, and examples thereof include amine-based surfactants and monofatty acid glycerides as preferred antistatic agents.

Specific examples of the amine surfactant include myristyl diethanolamine, palmityl diethanolamine, stearyl diethanolamine, oleyl diethanolamine, arachidyl diethanolamine, behenyl diethanolamine, and more preferably palmityl diethanolamine Ethanol Amine, stearyl diethanolamine, and oleyl diethanolamine may be used in the form of a mixture of two or more of these amine-based surfactants.

Specific examples of the monofatty acid glyceride include glycerol monolaurate, glycerol monomyristate, glycerol monopalmitate, glycerol monostearate, glycerol monoarachiate, glycerol monobehenate, and more. Glyceryl monostearate is preferred, and two or more of these monofatty acid glycerides can also be selected and used as a mixture.

If the antistatic agent is less than 0.01% by mass, it is easy to become a film with poor antistatic properties. If it is added more than 3% by mass, the roller may be contaminated during film formation or processing, or the film surface may become sticky, which is not good. Furthermore, if a large amount of an antistatic agent is added to the B layer at the time of manufacture, the above-mentioned problems are easily caused. Therefore, it is preferable not to add an antistatic agent to the polypropylene resin composition for the B layer at the time of manufacture, or reduce The added amount is an antistatic agent added to the layer A within the above-mentioned amount range. Even in this case, the antistatic agent contained in the A layer can diffuse and move into the B layer, and then ooze out on the surface of the laminated film through the B layer. By setting the △ H of the B layer to be less than 82.0J / g, the difference between the △ H of the A layer and the △ H of the B layer (△ H of the △ HB layer of the A layer) is set to 2.0J / g to 40.0J / g, can promote the diffusion, movement, and exudation of the antistatic agent to the B layer, and obtain sufficient antistatic properties.

An anti-caking agent can also be added to layer B. As anticaking agents, inorganic anticaking agents such as silica, calcium carbonate, kaolin, zeolites, and fats can be used. Group fatty acid esters, organic anti-blocking agents such as ethylene bisamidide, acrylics, polystyrenes, and the like are appropriately selected and used. The preferred average particle diameter of the anti-caking agent is 0.5 μm to 5.0 μm, and more preferably 1.0 μm to 3.0 μm. If the average particle diameter is less than 0.5 μm, a large amount of anticaking agent is required to obtain good lubricity, which is not good. On the other hand, if it exceeds 5.0 μm, the surface roughness of the film may become too large to meet practical characteristics. So it's not good. The anti-caking agent is preferably set to 0.01 mass% to 0.3 mass% in the B layer. If it is less than 0.01% by mass, the film is not easy to lubricate, and if it is added more than 0.3% by mass, the film may be whitened, which is not preferable.

The layer A and / or the layer B of the present invention (the other layer in the case where there are layers other than these layers) may further contain other additives or other resins. Examples of other 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.

(Making method of film)

The biaxially stretched laminated polypropylene film of the present invention can be obtained by using an extruder to make polypropylene materials for layer A (polypropylene resin composition for layer A) and polypropylene materials for layer B (for layer B) Polypropylene-based resin composition) and other layer materials (resin composition for layer C) are melt-extruded to form an unstretched sheet, and the unstretched sheet is stretched by a predetermined method and heat-treated. The unstretched laminated film is obtained by using a plurality of extruders or feed blocks, multi-manifolds. The melt extrusion temperature is preferably about 200 ° C to 280 ° C. In order to obtain a good appearance laminated film without disturbing the layer in this temperature range, it is preferable that the viscosity of the polypropylene raw material for the A layer and the polypropylene raw material for the B layer is poor. (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, it is preferable to stretch the film in the length (MD) direction to preferably 3 to 8 times (more preferably 3 to 7 times) by a stretching roller of 120 ° C to 165 ° C, and then to the width (TD) direction. The elongation is preferably performed at a temperature of preferably 155 ° C to 175 ° C, more preferably 160 ° C to 163 ° C, preferably 4 to 20 times, more preferably 6 to 12 times.

Furthermore, heat fixation is performed while performing relaxation at a temperature of preferably 165 ° C to 176 ° C, more preferably 170 ° C to 176 ° C, still more preferably 172 ° C to 175 ° C, and preferably 2% to 10%. For the biaxial extension obtained in this way After the stretched polypropylene film is subjected to corona discharge, plasma treatment, flame treatment, etc. as necessary, it is wound by a winder to obtain a film roll.

As described above, the lower limit of the stretch magnification of the 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 165 ° C, more preferably 160 ° C, even 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 unevenness may arise. 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 it exceeds the above-mentioned upper limit, the thermal shrinkage rate may increase, or it may break during stretching. 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 previous stretched polypropylene films. 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 lower limit described above, it may not be sufficiently softened and break, or the heat shrinkage rate may change. high. The upper limit of the TD extension temperature is preferably 175 ° C, more preferably 170 ° C, even 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. Heat fixing can be performed at higher temperatures than previous stretched 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.

(Physical properties of film)

For the biaxially stretched laminated polypropylene film of the present invention, the thermal shrinkage in the MD direction at 150 ° C is preferably 0.2% to 10%, more preferably 0.3% to 9%, and even more preferably 0.5% to 8%. , Particularly preferably 0.7% to 7%, and most preferably 1% to 5%. The thermal shrinkage in the TD direction at 150 ° C is also the same. 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 stretched laminated polypropylene film of the present invention, the surface intrinsic resistance value is preferably 9.5 (LogΩ) to 13.5 (LogΩ), more preferably 10 (LogΩ) to 13 (LogΩ), and further preferably 10.5 (LogΩ ) To 12.5 (LogΩ). When the surface specific resistance value exceeds 13.5 (LogΩ), the antistatic ability may become insufficient.

The haze of the biaxially stretched laminated polypropylene film of the present invention is preferably 0.1% to 6%, more preferably 0.2% to 5%, still more preferably 0.3% to 4.5%, particularly preferably 0.4% to 4%. It is preferably 0.4% to 3.5%. 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 0.013, more preferably 0.014, and still more preferably 0.015. If it is less than the said range, the heat resistance and rigidity of a film will fall, workability will fall, and an appearance will become bad, and the effect of this invention cannot fully be acquired.

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.

The tensile elastic modulus in the MD direction of the biaxially stretched laminated polypropylene film of the present invention is preferably 2.0 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 3.4GPa, the best is 2.4GPa to 3.3GPa. Tensile elasticity in TD direction The modulus is preferably 3.8 GPa to 8 GPa, more preferably 4 GPa to 7.5 GPa, still more preferably 4.1 GPa to 7 GPa, and even more preferably 4.2 GPa to 6.5 GPa.

The dynamic friction coefficient of the biaxially stretched laminated polypropylene film of the present invention is preferably 0.2 to 0.4, more preferably 0.22 to 0.38, and even more preferably 0.24 to 0.36. This improves the processability of the film.

The biaxially stretched laminated polypropylene film of the present invention can be used as a sealing film, an insulating film for a capacitor or a motor, a back sheet for a solar cell, an inorganic oxide barrier film, ITO (Indium Tin Oxide), etc. A base film (base material layer) used for a transparent conductive film or the like. The lamination strength in the MD direction of the laminated film laminated with the above film is preferably 1.2N / 15mm to 2.5N / 15mm, more preferably 1.3N / 15mm to 2.3N / 15mm, and further preferably 1.4N / 15mm Up to 2.1N / 15mm. The method for measuring the lamination strength will be described later.

This application claims the benefit of priority based on Japanese Patent Application No. 2016-064051 filed on March 28, 2016. The entire contents of the specification of Japanese Patent Application No. 2016-064051 filed on March 28, 2016 are incorporated herein by reference.

[Example]

Hereinafter, the present invention is further described in detail through examples. However, the following examples do not limit the present invention, and may be changed without departing from the spirit of the present invention. Further implementations 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 were determined based on monodisperse polystyrene standards using gel permeation chromatography (GPC). GPC measurement conditions such as column and solvent are as follows.

Solvent: 1,2,4-trichlorobenzene

Column: TSKgel GMH _HR -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) Differential Scanning Thermal Analysis (DSC)

The thermal measurement was performed using a differential scanning calorimeter ("DSC-60" manufactured by Shimadzu Corporation). Approximately 5 mg of the raw material of the sample film was sealed in an aluminum pan for measurement. The raw materials for layer A and raw materials for layer B were respectively heated from room temperature to 230 ° C at a rate of 20 ° C / minute and held for 5 minutes. Then, the temperature was reduced to room temperature at a rate of 20 ° C / min, and the temperature was increased to 230 ° C from room temperature again at a rate of 20 ° C / min. The melting endothermic peak temperature (° C) and the area of the melting endothermic peak (△ H (J / g), total heat of fusion). Here, the baseline is set so that the curve is smoothly connected at the temperature before and after melting from the beginning of the endothermic wave to the end of the wave.

5) thickness

Regarding the thickness of each of the layers A and B, the biaxially stretched laminated polypropylene film was fixed with a modified urethane resin, the cross section of the fixed object was cut out with a microtome, and observed and measured with a differential interference microscope.

6) Thermal shrinkage at 150 ℃ (%)

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.

7) 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. When measuring the Young's modulus, test pieces each having a width of 15 mm and a length of 200 mm were cut in the MD direction and the TD direction, respectively.

8) 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.

9) Haze (unit:%)

The measurement was performed in accordance with JIS K7105.

10) 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.

11) Film density (g / cm ³ )

The density of the film was measured by a density gradient tube method in accordance with JIS K7112.

12) 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.

13) Surface appearance

The appearance of the surface is in the evaluation target area (1000 mm in width and 4000 mm in length). Light is transmitted from one side of the film surface, and the portion where the light is blocked due to the defect of the film as a black spot is observed by a camera on the opposite side. When the total number of defects having an area exceeding 25 mm ² was measured, the case where the total number of defects was less than 200 was evaluated as ○, and 200 or more was evaluated as ×.

14) Lamination strength in MD direction

The lamination strength was measured by the following procedure.

(a) Lamination with sealing film

Production was performed using a continuous dry laminator as follows.

The corona surface of the biaxially stretched laminated polypropylene film obtained in the examples and comparative examples was 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, an unstretched polypropylene film (Pylen (registered trademark) CT P1128, thickness 30 μm) manufactured by Toyobo Co., Ltd. was used.

(b) Determination of lamination strength

The laminated film obtained above was cut out in a short strip shape (length 200 mm, width 15 mm) having long sides in the MD direction. The laminated film and the sealing film were peeled using tweezers, and a tensile tester (Tensilon, Orientic) was used. (Manufactured by the company), T-shaped peeling was performed at a stretching speed of 200 mm / min under an environment of 23 ° C, and the peel 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)

The polypropylene homopolymer PP-1 shown in Table 1 was used in the layer A, and the polypropylene homopolymer PP-2 shown in Table 1 was used in the layer B. In addition, 0.5% by mass of stearyl diethanolamine was blended into the raw material of the layer A as an antistatic agent. In addition, Blend 0.15% by mass of silicon dioxide as an anti-caking agent in layer B. Layer A uses a 60mm extruder, and Layer B uses a 65mm extruder. It is extruded from a T die at 250 ° C as a sheet, cooled and solidified by a cooling roll at 30 ° C, and then MD at 135 ° C. The direction extends to 4.5 times. Then, the two ends of the film width direction were clamped in a tenter by a clamp in a tenter, and after preheating at 175 ° C, it was extended to 8.2 times in the width direction at 160 ° C, and was thermally fixed at 170 ° C while relaxing 6.7%. A biaxially stretched laminated polypropylene film obtained by laminating each of the A layer and the B layer was obtained. The layer B side of the laminated polypropylene film was corona-treated, and was taken up by a winder. The thickness of the obtained film was 20 μm. Table 1 shows the structure of the polypropylene constituting the film, and Table 2 shows the film forming conditions. The physical properties of the obtained film are shown in Table 3.

(Examples 2 to 10, Comparative Examples 1 to 3)

Except having used the polypropylene shown in Table 1 and Table 3, and using the manufacturing conditions shown in Table 2 and Table 3, it carried out similarly to Example 1, and obtained the biaxially stretched laminated polypropylene film. Example 9 and Example 10 are examples of two types of three-layer films using a feed block with layer A as the core layer and layer B as the two surface layers. Comparative Example 3 is an example in which the B layer is not laminated. The film physical properties are shown in Table 3.

[Table 3A]

The biaxially stretched laminated polypropylene films obtained in Examples 1 to 10 had low thermal shrinkage and high Young's modulus (rigidity). Furthermore, the surface inherent resistance is small and the antistatic ability is excellent, the dynamic friction coefficient is small, the bag making processability is excellent, and the lamination strength is also high.

In contrast, the film of Comparative Example 1 was manufactured using the A layer having ΔH less than the B layer as the core layer, and the heat-fixing temperature was lower than the preferred temperature, so the Young's modulus became small.

The film of Comparative Example 2 uses a layer B having a ΔH greater than the A layer for the outermost layer (surface layer), and therefore a film having a large surface specific resistance and a high coefficient of dynamic friction.

The film of Comparative Example 3 is an example of a single-layer film having only layer A. The surface inherent resistance and dynamic friction coefficient become larger, and the lamination strength is also lowered.

In the film of Comparative Example 4, the ΔH of the B layer is the same as the ΔH of the A layer and the difference between ΔH = 0. Therefore, the surface inherent resistance is large.

[Industrial availability]

The biaxially stretched laminated polypropylene film of the present invention is excellent in heat resistance and excellent in antistatic properties. In addition, it also has high rigidity, so when it is used as a packaging film, it can be reduced in thickness, and low cost and light weight can be achieved. In addition, it can be processed at a high temperature during coating or printing, so not only can production efficiency be achieved, but also coating agents, inks, laminating adhesives, etc. that were not easy to use before can be used. The biaxially stretched laminated polypropylene film of the present invention can also be used for the insulation film of capacitors or motors, the back sheet of solar cells, and the resistance of inorganic oxides. Barrier film, base film of transparent conductive film such as ITO, etc.

Claims (8)

A biaxially stretched laminated polypropylene film is a laminated film containing at least two or more layers of polypropylene-based resin compositions having different crystallinity. The melting endothermic peak area measured by a differential scanning calorimeter at a heating rate of 20 ° C./minute is set. When it is △ H, it has: A layer made of polypropylene resin composition with △ H of 78.0J / g or more; and B layer made of △ H less than 82.0J / g and having The ΔH is composed of a polypropylene resin composition having a ΔH lower than 2.0J / g to 40.0J / g; the B layer is present on at least one of the outermost surfaces. The biaxially stretched laminated polypropylene film according to claim 1, wherein the ratio of the total thickness of the aforementioned B layer to the total thickness of the aforementioned A layer (the entire B layer / the entire A layer) is 0.01 to 0.5, and the aforementioned B layer The total thickness is 0.5 μm to 4 μm. The biaxially stretched laminated polypropylene film according to claim 1 or 2, further comprising a polypropylene resin having a thickness of 0.01 μm to 1.0 μm and a ΔH exceeding 76.0 J / g on the outermost surface side of the aforementioned layer B. The other layers of the composition. The biaxially stretched laminated polypropylene film according to claim 1 or 2, wherein the melt flow rate of the entire film is from 2.0 g / 10 minutes to 10.5 g / 10 minutes. The biaxially stretched laminated polypropylene film according to claim 1 or 2, wherein the surface inherent resistance value (LogΩ) of the entire film is 13.5 or less. The biaxially stretched laminated polypropylene film according to claim 1 or 2, wherein the dynamic friction coefficient of the entire film is 0.4 or less. The biaxially stretched laminated polypropylene film as described in claim 1 or 2, wherein the thermal shrinkage at 150 ° C is less than 10.0% in the longitudinal direction and the transverse direction, and the tensile elastic modulus in the longitudinal direction is 2.0 GPa or more, and the transverse tensile The tensile elastic modulus is 3.8 GPa or more. The biaxially stretched laminated polypropylene film as described in claim 1 or 2, wherein the longitudinal lamination strength after lamination is 1.2N / 15mm or more.