TWI629301B - Oriented polypropylene film - Google Patents

Abstract

The present invention provides an extended polypropylene film which has a low shrinkage ratio comparable to polyethylene terephthalate (PET) at 150 ° C and which is highly rigid. The extended polypropylene film of the present invention is a polypropylene resin constituting the film, and a propylene-based polymer satisfying the following requirements (a) to (c) is used, and the extended polypropylene film satisfies the following requirements (d) and (e): (a The meso-penta-component ratio is 96% or more; (b) the content of the comonomer other than propylene is 0.5 mol% or less; (c) the melt flow rate (MFR) is 0.5 g/10 min or more, 20 g/ (10) When the scattering intensity of the 110 surface of the α-type crystal of the polypropylene measured by the wide-angle X-ray scattering method is plotted against the azimuth angle, the half value width of the maximum peak is 30 degrees or less; (e) The melting endothermic peak area (total heat of fusion) measured by the differential scanning pyrolyzer at a heating rate of 20 ° C / min is 115 J / g or more, and the ratio of the area below 150 ° C (150 ° C heat of fusion) to the total heat of fusion ( The heat of fusion at 150 ° C / total heat of fusion is 0.12 or less.

Description

Extended polypropylene film

This invention relates to an extended polypropylene film. More specifically, the present invention relates to an extended polypropylene film which can be preferably used in various fields requiring high dimensional stability and high rigidity, and is excellent in heat resistance and mechanical properties.

Previously, polypropylene stretch films have been widely used in a wide range of applications such as packaging applications for foods and various commodities, electrical insulation applications, and surface protective films. However, the shrinkage ratio of the prior polypropylene film at 150 ° C is several tens of %, compared with polyethylene terephthalate (PET) film, etc., the heat resistance is low, and the rigidity is also low, so Limited use.

Furthermore, the industry has proposed various techniques for improving the physical properties of polypropylene films. For example, a technique is known in which a film having a high stereoregularity and a narrow molecular weight distribution is used to form a stretched film, thereby obtaining a film having high-temperature rigidity and heat resistance (see Patent Document 1).

Further, a technique is known in which a stretched film is formed using polypropylene having high stereoregularity and a wide molecular weight distribution, whereby it can be preferably used as a capacitor film excellent in electrical insulating properties, mechanical properties, and the like (see Patent Literature 2).

In addition, it is known to use a lower molecular weight and to obtain a temperature fractionation method. A technique in which a dissolvable component of 0 ° C is a specific range of polypropylene to form a separator film is considered to be excellent in dimensional stability in a drying step and a printing step (see Patent Document 3).

However, the films described in Patent Documents 1 to 3 are difficult in terms of elongation, and mechanical properties such as impact resistance are also inferior.

Further, there is known a technique of promoting the formation of a lamella by adding a long-chain branch or a cross-linked polypropylene to a medium molecular weight component in a trace amount, thereby improving elongation and obtaining mechanical properties and heat resistance. A film excellent in withstand voltage characteristics and excellent in uniformity of physical properties (see Patent Document 4).

Further, there is known a technique in which a polypropylene having a substantially equal amount of a high molecular weight component and a low molecular weight component (or a low molecular weight component) and having a broad molecular weight distribution and a low amount of decahydronaphthalene soluble portion is used. Film formation, thereby achieving a balance between rigidity and workability (refer to Patent Document 5).

However, the films described in the above-mentioned Patent Documents 4 to 5 are not sufficiently heat-resistant at a high temperature exceeding 150 ° C, and have high heat resistance, and the polypropylene film excellent in impact resistance and transparency is unknown. . In other words, the films described in Patent Documents 4 to 5 do not exceed the range of the conventional polypropylene film, and their use is limited, and heat resistance such as, for example, a high temperature exceeding 150 ° C has not been paid attention to.

[Previous Technical Literature] [Patent Literature]

Patent Document 1: Japanese Laid-Open Patent Publication No. Hei 8-325327

Patent Document 2: Japanese Laid-Open Patent Publication No. 2004-175932

Patent Document 3: Japanese Laid-Open Patent Publication No. 2001-146536

Patent Document 4: Japanese Laid-Open Patent Publication No. 2007-84813

Patent Document 5: Japanese Patent Publication No. 2008-540815

The present invention has been studied in the context of the above-mentioned problems of the prior art. That is, it is an object of the present invention to provide an extended polypropylene film which has a low shrinkage ratio comparable to a polyethylene terephthalate (PET) film at 150 ° C and which is highly rigid.

The inventors of the present invention have diligently studied in order to achieve the object, and as a result, have completed the present invention. That is, the extended polypropylene film of the present invention is a stretch film of a propylene-based polymer which satisfies the following requirements (a) to (c), and satisfies the following requirements (d) and (e): (a) meso-rotation The meso pentad fraction is 96% or more; (b) the comonomer content other than propylene is 0.5 mol% or less; (c) the melt flow rate (MFR) is 0.5g/10min or more and 20g/10min or less; (d) When the scattering intensity of the 110-plane of the α-type crystal of the polypropylene measured by the wide-angle X-ray scattering method is plotted against the azimuth angle, the half value width of the maximum peak is 30 degrees or less; (e) The melting endothermic peak area (total heat of fusion) measured at a heating rate of 20 ° C / min using a differential scanning pyrolyzer is 115 J / g or more, and an area of 150 ° C or less (150 ° C heat of fusion) The ratio of the total heat of fusion (150 ° C heat of fusion / total heat of fusion) was 0.12 or less.

The so-called stretch film is industrially referred to as uniaxial, simultaneous biaxial, and Sub-biaxial or the like is used to extend the film having an alignment, and the degree of alignment can be estimated by, for example, wide-angle X-ray diffraction or small-angle X-ray scattering, refractive index, or the like. In the present invention, the degree of alignment of the stretched film is defined by wide-angle X-ray diffraction.

In the present invention, it is preferred that the long period dimension obtained from the long-period scattering peak in the main alignment direction measured by the small angle X-ray scattering method is 40 nm or more. Further, in the present invention, it is preferred that the stretched film of the present invention is a film having a thickness of from 3 μm to 100 μm and extending at least uniaxially. Further, in the present invention, it is preferable that the heat shrinkage ratio in the TD direction at 150 ° C and the heat shrinkage ratio in the MD direction at 150 ° C are both 10% or less. Further, in the present invention, it is preferred that the film has a haze of 6% or less.

According to the stretched polypropylene film of the present invention, it exhibits a low shrinkage ratio and a high rigidity comparable to a polyethylene terephthalate (PET) film at 150 ° C, and can be film-formed.

Further, the extended polypropylene film of the present invention can maintain various physical properties even when exposed to an environment of 150 ° C or higher. Therefore, it can be used in a high-temperature environment that is not conceived in the conventional polypropylene film, and can be used in a wide range of applications. It is preferably applied. For example, by using the extended polypropylene film of the present invention as a substrate layer and a surface layer heat seal layer or gas barrier layer, it can be used in various packaging applications. Further, it can also be used as a substrate for extrusion lamination. Further, in the case where the stretched polypropylene film of the present invention or the laminated film using the stretched polypropylene film of the present invention is heat-sealed, by setting the heat-sealing temperature to be high, the heat-sealing strength is increased, and therefore, it is possible to increase The line speed such as bag making processing increases productivity. and then, When high temperature treatment such as retort is performed after bag making, the amount of deformation of the bag can also be suppressed.

Fig. 1 is a graph for explaining the azimuthal correlation and the half-value width of the diffraction intensity of the 110-plane of the α-type crystal in the wide-angle X-ray diffraction pattern of the extended polypropylene film.

2 is a differential scanning calorimeter (DSC) chart of the extended polypropylene film obtained in Example 1 and Comparative Example 1.

The present invention relates to an extended polypropylene film which is excellent in dimensional stability and mechanical properties at a high temperature. The stretched polypropylene film of the present invention is: (1) The stretched polypropylene film of the present invention is a stretch film of a propylene-based polymer which satisfies the following requirements (a) to (c), and satisfies the following requirements (d) and (e) ): (a) the meso-penta-component ratio is 96% or more; (b) the comonomer content other than propylene is 0.5 mol% or less; (c) the melt flow rate (MFR) is 0.5 g/10 min Above, 20 g/10 min or less; (d) plotting the scattering intensity of the 110 surface of the α-type crystal of the polypropylene measured by the wide-angle X-ray scattering method with respect to the azimuth angle, the half value width of the maximum peak is 30 degrees or less; (e) The melting endothermic peak area (total heat of fusion) measured at a heating rate of 20 ° C/min using a differential scanning pyrolyzer is 115 J/g or more, and an area of 150 ° C or less (150 ° C heat of fusion) relative to total melting The heat ratio (150 ° C heat of fusion / total heat of fusion) is 0.12 or less; (2) additionally, preferably, according to small angle X-ray scattering The long period dimension obtained by measuring the long-period scattering peak in the main alignment direction was 40 nm or more.

(3) Further, it is preferable that the stretched polypropylene film of the present invention is a film having a thickness of from 3 μm to 100 μm and extending at least uniaxially.

(4) Further, it is preferable that the heat shrinkage ratio in the TD direction at 150 ° C and the heat shrinkage ratio in the MD direction at 150 ° C are both 10% or less.

(5) Further, it is preferable that the haze is 6% or less.

(polypropylene resin)

The polypropylene-based resin used in the present invention is not particularly limited, and for example, a propylene homopolymer or a copolymer of propylene and ethylene and/or an α-olefin having 4 or more carbon atoms can be used.

The polypropylene resin constituting the film is preferably a propylene homopolymer having substantially no comonomer, and even when the comonomer is contained, the amount of the comonomer is 0.5 mol% or less. The upper limit of the amount of the comonomer is preferably 0.3 mol%, and more preferably 0.1 mol%. If it is in the above range, the crystallinity may be improved, and the heat shrinkage rate at a high temperature may be decreased. Further, a small amount of a comonomer may be contained insofar as the crystallinity is not remarkably lowered.

The polypropylene resin constituting the film is more preferably a propylene homopolymer obtained only from a propylene monomer, and the propylene homopolymer is most excluding a heterogeneous bond such as a head-to-head linkage. good.

(stereoregularity of polypropylene resin)

The index of the stereoregularity of the polypropylene resin constituting the film, that is, the lower limit of the meso pentad fraction measured by ¹³ C-NMR (carbon 13 nuclear magnetic resonance) was 96%. The lower limit of the meso pentad fraction is preferably 96.5%, more preferably 97%. When it is in the above range, the crystallinity may be improved, and the heat shrinkage rate at a high temperature may be further lowered. The upper limit of the meso pentad fraction is preferably 99.8%, more preferably 99.6%, and still more preferably 99.5%. If it is within the above range, actual manufacturing may become easy.

The lower limit of the meso-average chain length of the polypropylene resin constituting the film is preferably 100, more preferably 120, still more preferably 130. If it is in the above range, the crystallinity may be improved, and the heat shrinkage rate at a high temperature may be decreased. In practical terms, the upper limit of the meso average chain length is preferably 5,000.

In practical terms, the lower limit of the soluble fraction of the xylene of the polypropylene resin constituting the film is preferably 0.1% by mass. The upper limit of the xylene soluble portion is preferably 7% by mass, more preferably 6% by mass, still more preferably 5% by mass. If it is in the above range, the crystallinity may be improved, and the heat shrinkage rate at a high temperature may be decreased.

(melt flow rate of polypropylene resin)

The lower limit of the melt flow rate (MFR) (230 ° C, 2.16 kgf) of the polypropylene resin is 0.5 g/10 min. The lower limit of MFR is preferably 1.0 g/10 min, more preferably 1.3 g/10 min, further preferably 1.5 g/10 min, further preferably 2.0 g/10 min, particularly preferably 4.0 g/10 min, preferably 6.0 g. /10min. If it is within the above range, the mechanical load may be small, and extrusion and elongation may become easy. The upper limit of the MFR is 20 g/10 min, preferably 17 g/10 min, more preferably 16 g/10 min, and still more preferably 15 g/10 min. If it is in the above range, the elongation may be easy, the thickness unevenness may be reduced, or the elongation temperature and the heat setting temperature may be easily increased, and the heat shrinkage ratio may be further lowered.

(molecular weight of polypropylene resin)

The lower limit of the number average molecular weight (Mn) of the polypropylene resin constituting the film as measured by Gel Permeation Chromatography (GPC) is preferably 20,000, more preferably 22,000, still more preferably 24,000, particularly preferably 26000, the best is 27000. If it is in the above range, the following advantages may occur: elongation becomes easy, thickness unevenness is reduced, elongation temperature and heat setting temperature are easily increased, and heat shrinkage rate is low. The upper limit of Mn is preferably 200,000, more preferably 170,000, still more preferably 160,000, and particularly preferably 150,000. If it is in the above range, the effect of the present invention, such as the effect of a low molecular weight substance, that is, a low heat shrinkage rate at a high temperature, can be easily obtained, and the elongation becomes easy.

The lower limit of the mass average molecular weight (Mw) of the polypropylene resin constituting the film by GPC is preferably 180,000, more preferably 200,000, still more preferably 230,000, still more preferably 240,000, particularly preferably 250,000, and most preferably 270000. . If it is in the above range, the following advantages may occur: elongation becomes easy, thickness unevenness is reduced, elongation temperature and heat setting temperature are easily increased, and heat shrinkage rate is low. The upper limit of Mw is preferably 500000, more preferably 450,000, further preferably 420,000, particularly preferably 410,000, and most preferably 400,000. If it is within the above range, the mechanical load may be small, and extrusion and elongation may become easy.

(Molecular weight distribution of polypropylene resin)

The polypropylene resin used in the present invention preferably has the following characteristics. In other words, when the gel permeation chromatography (GPC) accumulation curve of the polypropylene resin constituting the film is measured, the lower limit of the amount of the component having a molecular weight of 100,000 or less is preferably 35 mass%, more preferably 38 mass%, and further preferably For 40 mass %, particularly preferably 41% by mass, most preferably 42% by mass. If it is in the above range, the effect of the present invention, such as a low heat shrinkage rate at a high temperature, which is effective for obtaining a low molecular weight substance, can be easily obtained, and the elongation becomes easy. The upper limit of the amount of the component having a molecular weight of 100,000 or less on the GPC cumulative curve is preferably 65 mass%, more preferably 60 mass%, still more preferably 58 mass%, particularly preferably 56 mass%, and most preferably 55 mass%. If it is in the above range, the elongation may be easy, the thickness unevenness may be reduced, or the elongation temperature and the heat setting temperature may be easily increased, and the heat shrinkage rate may be lowered.

In general, the breadth index of the molecular weight distribution is a mass average molecular weight (Mw) / number average molecular weight (Mn), and the lower limit of the mass average molecular weight (Mw) / number average molecular weight (Mn) of the polypropylene resin used in the present invention is preferably 4, more preferably 4.5, further preferably 5, particularly preferably 5.5, and most preferably 6. The upper limit of Mw/Mn is preferably 30, more preferably 25, still more preferably 22, particularly preferably 21, most preferably 20. When Mw/Mn is in the above range, actual production is easy.

Furthermore, the molecular weight distribution of the polypropylene can be adjusted by using a series of equipment to polymerize components having different molecular weights in multiple stages; and mixing the components having different molecular weights in an off-line state using a kneading machine; The catalysts having different properties are blended and polymerized; or a catalyst or the like which can achieve a desired molecular weight distribution is used.

The extended polypropylene film of the present invention is characterized by its structure, especially the alignment of the film.

(optical alignment)

The extended polypropylene film generally has a crystal orientation, and its direction and process Degree will have a greater impact on the physical properties of the membrane. The degree of crystal alignment varies depending on the molecular structure of the polypropylene used, or the process or conditions in the manufacture of the film. In addition, the orientation direction of the extended polypropylene film can be determined by using a wide-angle X-ray diffraction method to cause X-rays to be incident perpendicularly to the film surface, and measuring the azimuthal correlation of the scattered peaks from the crystal. Sex. In detail, the extended polypropylene film is typically an alpha-type crystal structure having a monoclinic crystal. Further, when the azimuthal correlation of the scattering intensity of the 110 surface (face spacing: 6.65 angstrom) was measured for the α-type crystal by the wide-angle X-ray diffraction method, it was found that the system had a strong alignment mainly on the uniaxial axis. That is, when the scattering intensity of the 110-plane from the α-type crystal is plotted against the azimuth angle, the strongest peak is observed in the vertical direction of the alignment of the molecular axes. In the present invention, the degree of alignment is defined by the half value width of the maximum peak.

Further, a typical pattern is shown in Fig. 1 regarding the azimuthal dependence of the scattering of the 110-plane from the α-type crystal of polypropylene. In addition, in FIG. 1, the half value width of the main peak (maximum peak) of the azimuth correlation of 110 plane is shown.

In the extended polypropylene film of the present invention, when the scattering intensity of the 110 surface measured by the wide-angle X-ray scattering method is plotted against the azimuth angle, the half value width of the maximum peak is 30 degrees or less. The upper limit of the half value width is preferably 29 degrees, more preferably 28 degrees. When the half value width of the azimuthal correlation from the scattering intensity of the 110 surface is larger than the above range, the alignment is insufficient, and the heat resistance and rigidity are insufficient. The lower limit of the half value width of the azimuthal correlation from the scattering intensity of the 110 surface is preferably 5 degrees, more preferably 7 degrees, and still more preferably 8 degrees. If the half value width of the 110 faces is smaller than the aforementioned range, the impact resistance may be lowered or the distribution may be generated. Breaking.

(wide-angle X-ray diffraction device)

The half value width specified in the present invention is preferably measured using X-rays having a high degree of parallelism, and it is preferred to use emitted light.

The X-ray generation source used in the wide-angle X-ray diffraction measurement may be a general device such as a tube type or a rotary type used in the laboratory, but it is preferably used to have a high parallelism and a high brightness. A high-intensity light source that emits light. In the emitted light, X-rays are difficult to diffuse and the brightness is also high, so that the measurement can be performed with high precision and in a short time. For example, even a film sample having a thickness of several tens of micrometers can be measured for one film without the need for a film. The combination is superimposed, and since the measurement with high precision can be performed, detailed crystal alignment evaluation can be performed. On the other hand, in the case of measuring X-rays having a low luminance, when a film sample having a thickness of several tens of micrometers is measured, if a plurality of film films are not overlapped, measurement takes a long time, and if a plurality of film films are overlapped, there is a case where a plurality of films are overlapped. The tendency is that the peak of the 110-plane scattering intensity is widened with respect to the azimuth due to a slight shift, and the obtained half-value width value is increased.

Examples of the apparatus that can illuminate the radiation having a high degree of parallelism and high luminance include, for example, a large-scale radiation facility such as SPring-8. For example, it is preferable to use a beam line BL03XU owned by Frontier Softmaterial Beamline (FSBL). The half value width of the present invention was determined.

(Small-Angle X-ray Scattering (SAXS))

In the extended polypropylene film of the present invention, it is preferred that the long period dimension is large. In general, a crystalline polymer has a repeating structure comprising crystals and amorphous The regular layer structure (periodic structure). Here, the size of the repeating unit including crystal and amorphous is referred to as a long period size. The long period size can be determined from the scattering peak angle of the long period structure from the main alignment direction measured by the small angle X-ray scattering method.

Regarding the long-period scattering peak obtained by small-angle X-ray scattering measurement of the extended polypropylene film of the present invention, it is necessary to clearly observe the peak in the main alignment direction. Here, the main alignment direction means that the direction of scattering caused by the long period of the polymer crystal can be more strongly observed in the two-dimensional X-ray scattering pattern. In the case of uniaxial extension, the main alignment direction is more consistent with the direction of extension; in the case of successive biaxial extension of longitudinal extension-lateral extension, although depending on the extension ratio in each direction, the main alignment direction is more and laterally extended. The direction is the same. The more clearly observed the long-period peak caused by the crystallization of the polymer, the formation of a long-period structure with higher order.

In the extended polypropylene film of the present invention, it is preferred that the long period dimension derived from the long-period scattering peak is 40 nm or more. The lower limit of the long period size is more preferably 41 nm, and further preferably 43 nm. When the long period size is smaller than the above range, the melting peak temperature is low, and thus heat resistance is insufficient. The upper limit of the long period size is preferably 100 nm, more preferably 90 nm, and still more preferably 80 nm. If the long period size is larger than the above range, crystallization or heat treatment takes a long time, and actual fabrication becomes difficult.

(small angle X-ray diffraction device)

The X-ray generation source used in the small-angle X-ray scattering measurement is not particularly limited, and a lamp type or a rotary type used in the laboratory can be used. In general, a high-intensity light source that emits high-intensity radiation can be used in the same manner as the X-ray generation source used in the wide-angle X-ray diffraction measurement described above. In particular, since the extended polypropylene film of the present invention has a large long period, the X-ray scattering caused by the long-period structure is located in the region of the smaller angle side. Therefore, if the X-ray apparatus of the laboratory has a large X-ray beam diameter and a short camera length, it is difficult to measure, and it is preferable to use X-rays to be difficult to diffuse, and the beam diameter can be controlled to several hundred micrometers or less. The emitted light with a higher brightness is measured over a longer camera length for the ultra-small angle region. At this time, the length of the camera is preferably 7 m or more.

(film crystallinity)

The stretched film of the present invention has a high crystallinity characteristic as described below. For example, the total heat of fusion in the temperature rise measurement by a differential scanning calorimeter (DSC) can be used as an indicator of crystallinity. The total heat of fusion corresponds to the melting endothermic peak area measured by a differential scanning pyrolyzer at a temperature increase rate of 20 ° C/min. The lower limit of the total heat of fusion is 115 J/g, preferably 117 J/g, more preferably 120 J/g. When the total heat of fusion is less than the above range, the crystallinity is insufficient, and heat resistance and rigidity are lowered. The upper limit of the total heat of fusion is preferably 150 J/g, more preferably 145 J/g, and still more preferably 140 J/g. When the total heat of fusion is higher than the above range, it may be necessary to carry out a long-term manufacturing step at a high temperature, and the actual production becomes difficult. The total heat of fusion can be controlled within the foregoing range by, for example, reducing the amount of comonomer or not using comonomer; increasing stereoregularity; setting the elongation temperature or heat setting temperature to a high temperature; performing off-line annealing treatment Wait.

Among the melting endothermic peak areas, the area of the portion below 150 ° C corresponds to 150 ° C heat of fusion. In the present invention, the upper limit of the ratio of the heat of 150 ° C to the total heat of fusion (150 ° C heat of fusion / total heat of fusion) obtained by the area of the endothermic peak of 150 ° C or less is 0.12, preferably 0.11, more preferably 0.10. If it is larger than this upper limit, heat resistance of high temperature may fall. The lower limit of the heat of fusion/total heat of fusion at 150 ° C is preferably 0, more preferably 0.005, still more preferably 0.01. The heat of fusion at 150 ° C can be controlled, for example, by reducing the amount of comonomer or not using a comonomer; setting the elongation temperature or heat setting temperature to a high temperature; performing an off-line annealing treatment or the like.

In the case of the conventional polypropylene film, even if the melting peak temperature is about 170 ° C, it is confirmed that the peak due to the start of melting is increased from the vicinity of 140 ° C when measured by DSC. The heat resistance at ° C, then at 150 ° C, the heat shrinkage rate increases sharply. However, in the extended polypropylene film of the present invention, even at 150 ° C, the rise of the peak is small, and it is considered that the heat shrinkage at 150 ° C is obtained. That is, the extended polypropylene film of the present invention can maintain various physical properties even when exposed to an environment of 150 ° C or higher, and can be used in a high temperature environment which was not originally imagined by the extended polypropylene film. Furthermore, the melting start can be determined from the DSC curve. The above DSC diagram of Example 1 is shown in Fig. 2 as an example of the stretched film of the present invention.

(melting peak temperature of the film)

The lower limit of the melting peak temperature measured by the differential scanning calorimeter at a temperature rising rate of 20 ° C / min is preferably 165 ° C, more preferably 167 ° C. If the melting peak temperature is within the above range, the heat shrinkage rate at a high temperature may decrease. The upper limit of the melting peak temperature is preferably 180 ° C, more preferably 178 ° C, and still more preferably 177 ° C. If the melting peak temperature is within the above range, actual manufacturing may become easy. The melting peak temperature can be controlled within the foregoing range by, for example, reducing the amount of comonomer or not using comonomer; increasing stereoregularity; setting the elongation temperature or heat setting temperature to a high temperature; performing off-line annealing treatment Wait.

(membrane property)

The extended polypropylene film of the present invention exhibits the following physical properties. In addition, the following physical properties can be measured and evaluated by, for example, the method described in the following examples.

(heat shrinkage rate)

The stretched polypropylene film of the present invention is a stretched film mainly composed of a polypropylene resin, and preferably has a heat shrinkage ratio of 10% or less in the MD direction and the TD direction at 150 °C. Here, the MD direction refers to the traveling direction of the film (sometimes referred to as the longitudinal direction or the vertical axis direction); the TD direction refers to the direction perpendicular to the traveling direction of the film (sometimes referred to as the lateral direction or Width direction). In the previously extended polypropylene film, the heat shrinkage rate at 150 ° C in the MD direction and the TD direction was 15% or more, and the heat shrinkage ratio at 120 ° C was about 3%. By setting the heat shrinkage rate to 10% or less, a film excellent in heat resistance can be obtained.

The lower limit of the 150 ° C heat shrinkage ratio in the MD direction and the TD direction of the extended polypropylene film of the present invention is preferably 0.2%, more preferably 0.3%, still more preferably 0.5%, particularly preferably 0.7%, most preferably 1.0. %. When the heat shrinkage ratio at 150 ° C is within the above range, there is a possibility that the actual production becomes easy or the thickness unevenness is reduced in terms of cost and the like. The upper limit of the 150 ° C heat shrinkage ratio in the MD direction and the TD direction is preferably 10%, more preferably 9%, and still more preferably 8%. The best is 7%, and the best is 5%. When the heat shrinkage rate at 150 ° C is within the above range, it is easier to use in applications or processes that may be exposed to high temperatures of about 150 ° C. Further, the heat shrinkage rate at 150 ° C is about 1.5%, and can be achieved by, for example, increasing the low molecular weight component and adjusting the stretching conditions or the fixing conditions. However, if the temperature is reduced to 1.5% or less, it is preferred to carry out the annealing treatment off-line. .

(impact resistance)

The lower limit of the impact resistance (23 ° C) of the extended polypropylene film of the present invention is preferably 0.6 J, more preferably 0.7 J. When the impact resistance is within the above range, it has sufficient toughness as a film, and no breakage or the like occurs during handling. In practical terms, the upper limit of the impact resistance is preferably 2 J, more preferably 1.8 J, still more preferably 1.6 J, and particularly preferably 1.5 J. For example, when there are many low molecular weight components, when the molecular weight of the whole is low, when the high molecular weight component is small, and when the molecular weight of the high molecular weight component is low, the impact resistance is lowered, and therefore, The purpose is to adjust the components, and the impact resistance is controlled within the above range.

(haze)

The lower limit of the haze of the stretched polypropylene film of the present invention is preferably 0.1%, more preferably 0.2%, still more preferably 0.3%, and particularly preferably 0.4%, as an actual value. The upper limit of the haze is preferably 6%, more preferably 5%, still more preferably 4.5%, particularly preferably 4%, most preferably 3.5%. If the haze is within the above range, it may be easy to use in applications requiring transparency. The haze has a tendency that, for example, when the stretching temperature and the heat setting temperature are too high, the chill roll (CR) temperature is high and the raw material sheet is cold. However, when the speed is slow, when the low molecular weight is too large, the haze is deteriorated. Therefore, the haze can be controlled within the above range by adjusting the conditions.

(Young's modulus)

When the extended polypropylene film of the present invention is a biaxially stretched film, the lower limit of the Young's modulus (23 ° C) in the MD direction is preferably 2 GPa, more preferably 2.1 GPa, and still more preferably 2.2 GPa, particularly preferably 2.3GPa, the best is 2.4GPa. The upper limit of the Young's modulus in the MD direction is preferably 4 GPa, more preferably 3.7 GPa, still more preferably 3.5 GPa, particularly preferably 3.4 GPa, and most preferably 3.3 GPa. If the Young's modulus in the MD direction is within the above range, the actual manufacturing may be easy or the MD-TD balance may be improved.

When the extended polypropylene film of the present invention is a biaxially stretched film, the lower limit of the Young's modulus (23 ° C) in the TD direction is preferably 3.8 GPa, more preferably 4 GPa, and still more preferably 4.1 GPa, particularly preferably 4.2GPa. The upper limit of the Young's modulus in the TD direction is preferably 8 GPa, more preferably 7.5 GPa, still more preferably 7 GPa, and particularly preferably 6.5 GPa. If the Young's modulus in the TD direction is within the above range, the actual manufacturing may be easy or the MD-TD balance may be improved. Furthermore, the Young's modulus can be increased by, for example, increasing the stretching ratio, and in the case of the MD-TD extension, the MD stretching magnification can be set lower, and the TD stretching magnification can be set higher. And increase the Young's modulus in the TD direction.

(thickness uniformity)

The lower limit of the thickness uniformity of the extended polypropylene film of the present invention is preferably 0%, more preferably 0.1%, still more preferably 0.5%, particularly preferably 1%. The upper limit of the thickness uniformity is preferably 20%, more preferably 17%, and still more preferably 15%. The best is 12%, and the best is 10%. When the thickness uniformity is within the above range, it is less likely to cause a problem in subsequent processing such as coating or printing, and it is easy to use in applications requiring precision.

(film density)

The density of the polypropylene film of the present invention extends the lower limit is preferably 0.910g / cm ^3, more preferably 0.911g / cm ^3, further preferably 0.912g / cm ^3, particularly preferably 0.913g / cm ^3. If the film density is within the above range, the crystallinity may be high and the heat shrinkage rate may be decreased. The upper limit of the film density is preferably 0.930 g/cm ³ , more preferably 0.928 g/cm ³ , still more preferably 0.926 g/cm ³ , and particularly preferably 0.925 g/cm ³ . If the film density exceeds the above upper limit, it may be practically difficult to manufacture. The film density can be increased by increasing the stretching ratio or elongation temperature, increasing the heat setting temperature, and performing off-line annealing.

(refractive index)

The lower limit of the refractive index (Nx) in the MD direction of the extended polypropylene film of the present invention is preferably 1.502, more preferably 1.503, still more preferably 1.504. The upper limit of Nx is preferably 1.520, more preferably 1.517, and still more preferably 1.515.

The lower limit of the refractive index (Ny) of the extended polypropylene film of the present invention in the TD direction is preferably 1.523, more preferably 1.525. The upper limit of Ny is preferably 1.535, more preferably 1.532.

The lower limit of the refractive index (Nz) in the thickness direction of the extended polypropylene film of the present invention is preferably 1.480, more preferably 1.489, and still more preferably 1.500. The upper limit of Nz is preferably 1.510, more preferably 1.507, and still more preferably 1.505.

(face matching coefficient)

The lower limit of the surface alignment coefficient of the extended polypropylene film of the present invention is preferably 0.0125 is more preferably 0.0126, still more preferably 0.0127, and particularly preferably 0.0128. The upper limit of the surface alignment coefficient is preferably 0.0155, more preferably 0.0150, still more preferably 0.0148, and particularly preferably 0.0145. The surface alignment coefficient can be made within the above range by adjusting the stretching ratio. If the surface alignment coefficient is within this range, the thickness unevenness of the film is also good.

(Method for producing polypropylene resin)

The polypropylene resin is obtained by polymerizing propylene as a raw material using a known catalyst such as a Ziegler-Natta catalyst or a metallocene catalyst. Among them, in order to eliminate the heterojunction, a Ziegler-Natta catalyst is used, and it is preferred to use a catalyst capable of performing polymerization with high stereoregularity.

A known method can be employed for the polymerization method of propylene. For example, a method of performing polymerization in an inert solvent such as hexane, heptane, toluene or xylene; a method of performing polymerization in a liquid monomer; A method in which a catalyst is added to a body, and polymerization is carried out in a gas phase state; or a method in which the methods are carried out by a combination of the methods.

(additive)

In the resin composition for film formation of the present invention, an additive or other resin may be added as needed. As the additive, for example, an antioxidant, an ultraviolet absorber, an antistatic agent, a lubricant, a nucleating agent, an adhesive, an antifogging agent, a flame retardant, an anti-caking agent, an inorganic or organic filler, and the like can be given. Examples of the other resin include a polypropylene resin other than the polypropylene resin used in the present invention; a copolymer of propylene and ethylene and/or an α-olefin having 4 or more carbon atoms, that is, a random copolymer; or various kinds of elasticity. Body and so on. Such additives or The resin may be polymerized sequentially using a multi-stage reactor; or may be blended with a polypropylene resin using a Henschel mixer; or the masterbatch may be pre-formed using a melt-kneading machine and then diluted to a specific concentration with polypropylene; or The entire amount is melted and kneaded in advance and used.

(Method of manufacturing extended polypropylene film)

The stretched film of the present invention may be a uniaxially stretched film in the longitudinal direction (MD direction) or the transverse direction (TD direction), but is preferably a biaxially stretched film. The biaxial extension may be a sequential biaxial extension or a simultaneous biaxial extension. In the present invention, a film having a low heat shrinkage rate at 150 ° C which was not expected from the prior polypropylene film can be obtained by extending at least uniaxially.

Hereinafter, a method of manufacturing a sequential biaxially stretched film which is a longitudinal extension-lateral extension, which is a preferred embodiment, will be described.

First, the molten polypropylene resin was heated by a uniaxial or biaxial extruder and extruded onto a cooling roll to obtain an unstretched film. As the melt extrusion conditions, the resin temperature was set to 200 ° C to 280 ° C, extruded from a T-die in a sheet form, and cooled and solidified by a cooling roll at a temperature of 10 ° C to 100 ° C. Next, the film is stretched by 3 to 8 times in the length (MD) direction by an extension roller of 120 ° C to 165 ° C, preferably 3 to 7 times, and then 155 ° C in the width (TD) direction. The temperature is 175 ° C, preferably 158 ° C ~ 170 ° C for 4 times ~ 20 times, preferably 6 times ~ 12 times extension. Further, heat treatment is carried out at a temperature of 165 ° C to 175 ° C, preferably 166 ° C to 173 ° C, allowing a relaxation of 1% to 15%. The polypropylene film thus obtained was subjected to a corona discharge treatment on at least one side as needed, and then wound up by a winder, thereby obtaining a reel sample.

The lower limit of the stretching ratio of MD is preferably 3 times, more preferably 3.5 times. If the MD stretching ratio does not reach the above lower limit, there is a possibility that the film thickness is uneven. The upper limit of the stretching ratio of MD is preferably 8 times, more preferably 7 times. If the MD extension ratio exceeds the above upper limit, it is likely that the subsequent TD extension becomes difficult.

The lower limit of the extension temperature of the MD is preferably 120 ° C, more preferably 125 ° C, and still more preferably 130 ° C. If the elongation temperature of the MD does not reach the above lower limit, the mechanical load may increase, the thickness unevenness may increase, or the film may have a rough surface. The upper limit of the extension temperature of the MD is preferably 165 ° C, more preferably 160 ° C, still more preferably 155 ° C, and particularly preferably 150 ° C. A higher extension temperature is preferred for lowering the heat shrinkage rate, but it is possible that the film adheres to the roll to become unstretchable or to cause surface roughness.

The lower limit of the stretching ratio of TD is preferably 4 times, more preferably 5 times, and still more preferably 6 times. If the stretching ratio of TD does not reach the above lower limit, there is a possibility that the thickness is uneven. The upper limit of the TD stretching ratio is preferably 20 times, more preferably 17 times, further preferably 15 times, and particularly preferably 12 times. If the stretching ratio of TD exceeds the above upper limit, the heat shrinkage rate may increase, or breakage may occur during stretching.

Regarding the preheating temperature in the TD extension, in order to rapidly increase the film temperature to the vicinity of the extension temperature, it is preferably set to be 5 ° C to 15 ° C higher than the extension temperature.

The extension of the TD is preferably carried out at a higher temperature than the previously extended polypropylene film. The lower limit of the extension temperature of TD is preferably 155 ° C, more preferably 157 ° C, and still more preferably 158 ° C. If the extension temperature of TD does not reach the above lower limit, the fracture may not be sufficiently softened to cause breakage or the heat shrinkage rate may be increased. The upper limit of the TD extension temperature is preferably 175 ° C, more preferably 170 ° C, and thus Good for 168 ° C. In order to lower the heat shrinkage rate, the TD stretching temperature is preferably higher, but if it exceeds the above upper limit, not only the low molecular weight component may be melted and recrystallized, but the alignment may be reduced, and surface roughening or film whitening may occur.

The stretched film is usually heat set. In the present invention, heat setting can be carried out at a temperature higher than that of the previously extended polypropylene film. The lower limit of the heat setting temperature is preferably 165 ° C, more preferably 166 ° C. If the heat setting temperature does not reach the above lower limit, the heat shrinkage rate may increase. Further, there is a problem in that it takes a long time to reduce the heat shrinkage rate and the productivity is deteriorated. The upper limit of the heat setting temperature is preferably 175 ° C, more preferably 173 ° C. If the heat setting temperature exceeds the above upper limit, the low molecular weight component may be melted and recrystallized to cause surface roughness or film whitening.

It is preferred to carry out relaxation (mitigation) at the time of heat fixation. The lower limit of relaxation is preferably 2%, more preferably 3%. If the relaxation does not reach the above lower limit, the heat shrinkage rate may increase. The upper limit of relaxation is preferably 10%, more preferably 8%. If the relaxation exceeds the above upper limit, the thickness unevenness may increase.

Further, in order to reduce the heat shrinkage rate, the film produced in the above step may be temporarily wound into a roll shape and then annealed in an off-line state. The lower limit of the off-line annealing temperature is preferably 160 ° C, more preferably 162 ° C, and still more preferably 163 ° C. If the off-line annealing temperature does not reach the above 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 still more preferably 173 ° C. If the off-line annealing temperature exceeds the above upper limit, the transparency may be lowered or the thickness unevenness may be increased.

The lower limit of the off-line annealing time is preferably 0.1 minutes, more preferably 0.5 minutes. The clock is further preferably 1 minute. If the offline annealing time does not reach the above lower limit, the effect of annealing may not be obtained. The upper limit of the off-line annealing time is preferably 30 minutes, more preferably 25 minutes, and still more preferably 20 minutes. If the offline annealing time exceeds the above upper limit, productivity may be lowered.

The thickness of the film is set according to each application, and the lower limit of the film thickness is preferably 2 μm, more preferably 3 μm, still more preferably 4 μm. The upper limit of the film thickness is preferably 300 μm, more preferably 250 μm, still more preferably 200 μm, still more preferably 150 μm, particularly preferably 100 μm, and most preferably 50 μm.

The stretched polypropylene film thus obtained is usually formed into a film having a width of from 2000 mm to 12000 mm and a length of from about 1000 m to about 50,000 m, and is wound into a roll shape. Further, it is divided into a slit roll having a width of 300 mm to 2000 mm and a length of 500 m to 5000 m, and is supplied for each application.

The extended polypropylene film of the present invention has excellent characteristics not previously possessed as described above. When it is used as a packaging film, since it is highly rigid, it can be thinned, and cost reduction and weight reduction can be achieved.

Further, since the extended polypropylene film of the present invention has high heat resistance, it can be processed at a high temperature at the time of coating or printing, and production efficiency can be improved, and a coating agent or ink which has been previously difficult to use can be used, and lamination can be carried out. Agents, etc. Further, the extended polypropylene film of the present invention can also be used as an insulating film for a capacitor or a motor, a back sheet of a solar cell, a barrier film of an inorganic oxide, or a transparent conductive film such as ITO (indium tin oxide). Basement membrane.

This case is based on the Japanese special offer No. 2013-152979 filed on July 23, 2013, and the Japanese special application filed on July 23, 2013. Japan's privileged application No. 2013-154673, which was filed on July 25, 2013, and Japan's privileged application No. 2013-154674, which was filed on July 25, 2013, and July 29, 2013 The benefit of the priority of Japanese Patent Application No. 2013-157049, filed on Jan. 29, 2013, and the Japanese Patent Application No. 2013-157050, filed on Jul. 29, 2013. Japan's Chartered Wishing No. 2013-152979, which was filed on July 23, 2013, Japan's Chartered Wishing No. 2013-152980, which was filed on July 23, 2013, and Japan's Chartered Wish, 2013, filed on July 25, 2013 Japanese Patent Application No. 2013-154674, filed on July 25, 2013, Japanese Patent Application No. 2013-157049, filed on July 29, 2013, and Japan filed on July 29, 2013 The entire contents of the specification of the Japanese Patent Application No. 2013-157050 are incorporated herein by reference.

[Examples]

Hereinafter, the present invention will be described in detail based on examples, but the present invention is not limited to the examples. The method for measuring the physical properties in the examples is as follows.

1) Stereo regularity

The measurement of the meso pentad fraction ([mmmm]%) and the meso average chain length was carried out using ¹³ C-NMR. The meso pentad fraction is calculated according to the method described in "Zambelli et al., Macromolecules, Vol. 6, p. 925 (1973); the meso-average chain length is based on "JCRandall's Polymer Sequence Distribution". It is calculated by the method described in Chapter 2 (1977) (Academic Press, New York). ^{The 13} C-NMR measurement was carried out under the following conditions: using a "AVANCE 500" manufactured by BRUKER Co., Ltd., 200 mg of the sample was dissolved at 135 ° C in a mixture of o-dichlorobenzene and toluene in a ratio of 8:2 (volume ratio), and ¹³ C-NMR was carried out at 110 °C.

2) Soluble soluble fraction (unit: mass%)

1 g of a polypropylene sample was dissolved in 200 ml of boiling xylene, left to cool, and then recrystallized in a constant temperature water bath at 20 ° C for 1 hour, and the ratio of the mass dissolved in the filtrate to the amount of the original sample was dissolved as xylene. Part (% by mass).

3) Melt flow rate (MFR) (unit: g/10min)

MFR was measured in accordance with JIS K7210 at a temperature of 230 ° C and a load of 2.16 kgf.

4) Molecular weight and molecular weight distribution

The molecular weight and molecular weight distribution were determined by gel permeation chromatography (GPC) based on monodisperse polystyrene. The measurement conditions such as the column and the solvent used in the GPC measurement are as follows.

Solvent: 1,2,4-trichlorobenzene

Column: TSKgel GMH _HR -H(20)HT×3

Flow rate: 1.0ml/min

Detector: RI

Measuring temperature: 140 ° C

The number average molecular weight (Mn), mass average molecular weight (Mw), and Z+1 are defined by the following formulas by the number of molecules (Ni) of the molecular weight (Mi) at each dissolution position on the GPC curve obtained through the molecular weight calibration curve. Average molecular weight (Mz+1).

Number average molecular weight: Mn = Σ (Ni‧Mi) / ΣNi

Mass average molecular weight: Mw = Σ (Ni‧Mi ² ) / Σ (Ni‧Mi)

Z+1 average molecular weight: Mz+1=Σ(Ni‧Mi ⁴ )/Σ(Ni‧Mi ³ )

Molecular weight distribution: Mw/Mn

Further, the molecular weight at the peak position of the GPC curve was defined as Mp.

When the baseline is not clear, it is set in the range of the elution peak on the high molecular weight side closest to the elution peak of the standard substance to the lowest position of the flat portion of the high molecular weight side.

5) Wide-angle X-ray diffraction

In the embodiment of the present invention, in the large-scale radiation light facility SPring-8, the second hatch of the beam line BL03XU owned by the Frontier Softmaterial Beamline (FSBL) is formed so that the X-ray source direction and the film surface are formed. The measurement film was set to a vertical angle, and was measured by Wide-Angle X-ray Scattering (WAXS). The measurement conditions are shown below.

The X-ray wavelength is 0.1 nm, and the detector uses an image plate (RIGAKU R-AXIS VII) or a CCD (charge coupled device) camera (Hamamatsu Photonics V7739P+ORCA R2) with an image intensifier, and is set according to The transmittance was calculated from the value of the ion chamber before and after the sample. Air scattering correction is performed on the obtained two-dimensional image taking into account dark noise and transmittance. The length of the camera was measured using cerium oxide (CeO ₂ ), and the position of the (110) plane was calculated using Fit2D (software manufactured by the European Synchrotron Radiation Facility [http://www.esrf.eu/processing/scientific/FIT2D/]). Angle profile.

6) Long period size obtained by small angle X-ray scattering method

In the large-scale radiation facility SPring-8, in the second exit of the beam line BL03XU owned by the Frontier Softmaterial BL Consortium (FSBL), the MD direction of the film is the up-and-down direction, the TD direction is the left-right direction, and the film surface and the X-ray are used. The measurement film was set such that the angle formed by the source direction was a vertical angle, and small angle X-ray (SAXS) measurement was performed. The measurement conditions are shown below.

The X-ray wavelength was 0.2 nm, and the length of the camera was about 7.7 m. The detector used an image plate (RIGAKU R-AXIS VII) to obtain a scattering image in which the scattering vector q was in the range of 0.01 (nm ^-1 ) to 0.5 (nm ^-1 ). Here, when θ is one half of the scattering angle 2θ, π is the pi, and λ is the wavelength of the X ray, the scattering vector q can be calculated by the equation q=4πsin θ/λ. The obtained scattering image is subjected to air scattering correction in consideration of dark noise and transmittance in the same manner as the WAXS measurement, and the accurate camera length is determined by using the protein adjusted by the oleic acid silver. . Using the aforementioned Fit2d software, a pattern of the width direction of the sample was calculated, and the scattering vector q (nm ^-1 ) was taken on the horizontal axis, and the common logarithm of the intensity I (q) was plotted on the vertical axis. Here, the calculation range of the graph is set to ±5 degrees in the width direction.

7) Differential Scanning Thermal Analysis (DSC)

The measurement was performed by using a differential scanning calorimeter ("DSC-60" manufactured by Shimadzu Corporation). About 5 mg was cut out from the sample film and sealed in an aluminum pan for measurement. Warming from room temperature to 20 ° C / min At 230 ° C, the melting endothermic peak temperature and the melting endothermic peak area (total heat of fusion) of the sample were measured. Here, the baseline is set in such a manner that the temperature before and after the melting is connected to a smooth curve in the range from the end of the endothermic peak to the end of the peak. Further, in the melting endothermic peak area, the area of the portion below 150 ° C was taken as 150 ° C heat of fusion.

8) Thermal shrinkage rate (unit: %)

The measurement was carried out by the following method in accordance with JIS Z 1712. The stretched film was cut in the MD direction and the TD direction by a width of 20 mm and a length of 200 mm, and was hung in a hot air oven at 150 ° C for 5 minutes. The length after heating was measured, and the ratio (percentage) of the length of the shrinkage to the original length was taken as the heat shrinkage ratio.

9) Young's modulus (unit: GPa)

The Young's modulus of the film in the MD direction and the TD direction was measured at 23 ° C according to JIS K 7127.

10) Impact resistance (unit: J)

The measurement was carried out at 23 ° C using a "membrane impact tester" manufactured by Toyo Seiki Co., Ltd.

11) Thickness uniformity (uneven thickness) (unit: %)

A sample having a square shape of 1 m in length was cut out from the wound film roll, and 10 pieces were respectively divided in the MD direction and the TD direction to prepare 100 samples for measurement. The thickness of the substantially central portion of the sample for measurement was measured by a contact type film thickness meter. Find the average value A of the obtained 100 data, and find the difference (absolute value) B between the minimum value and the maximum value. Calculate using the formula (B/A) × 100, and use the obtained value as the thickness of the film. All.

12) Haze (unit: %)

The measurement was carried out in accordance with JIS K7105.

13) Film density (unit: g/cm ³ )

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

14) Refractive index (Nx, Ny, Nz)

The measurement was carried out using an Abbe refractometer (manufactured by Atago Co., Ltd.). The refractive indices in the MD direction and the TD direction are respectively set to Nx and Ny, and the refractive index in the thickness direction is set to Nz.

15) Surface alignment coefficient P

Using the Nx, Ny, and Nz measured in the above 12), the plane alignment coefficient P was calculated according to the formula: P = [(Nx + Ny)/2] - Nz.

(Example 1)

As the polypropylene resin, a propylene homopolymer (Japan Polypropylene) having Mw/Mn = 7.7, Mz+1/Mn = 140, MFR = 5.0 g/10 min, meso pentad fraction [mmmm] = 97.3% was used. "Novatec (registered trademark) PP SA4L" manufactured by the company: the amount of comonomer is 0 mol%; hereinafter referred to as "PP-1").

The polypropylene resin was extruded in a sheet shape from a T-shaped mold at 250 ° C using a 60 mm extruder, and cooled and solidified by a cooling roll at 30 ° C, and then extended longitudinally by 4.5 times in the longitudinal direction (MD direction) at 135 ° C. Then, the both ends were clamped by a jig, introduced into a hot air oven, preheated at 170 ° C, and extended laterally by 8.2 times in the transverse direction (TD direction) at 160 ° C, and secondly, a relaxation of 6.7% was applied on one side. Heat treatment was performed at 168 °C. after that, The one side of the film was subjected to corona treatment, and wound up in a winder as the stretched polypropylene film of the present invention.

The thickness of the obtained film was 20 μm. The structure of the polypropylene constituting the film is shown in Table 1, and the film formation conditions are shown in Table 2. The physical properties of the obtained film were as shown in Table 3, the heat shrinkage rate was low, and the Young's modulus was high. Further, a graph obtained by differential scanning calorimetry (DSC) of the film is shown in Fig. 2 .

(Example 2)

As the polypropylene resin, a propylene homopolymer ("HU300" manufactured by Samsung Total Petrochemicals Co., Ltd.) having Mw / Mn = 8.9, Mz + 1 / Mn = 110, MFR = 3.0 g / 10 min, and [mmmm] = 97.1% was used. : the amount of comonomer is 0 mol%; hereinafter referred to as "PP-2"), and the preheating temperature of the lateral extension is 171 ° C, the lateral extension temperature is set to 161 ° C, and the heat treatment temperature after the lateral extension is set to The stretched polypropylene film of the present invention was obtained in the same manner as in Example 1 except that the temperature was 170 °C.

The thickness of the obtained film was 20 μm. The structure of the polypropylene constituting the film is shown in Table 1, and the film formation conditions are shown in Table 2. The physical properties of the obtained film are shown in Table 3.

(Example 3)

With respect to 90 parts by mass of the propylene homopolymer (PP-1) used in Example 1, a low molecular weight propylene having a molecular weight of 10,000 was added (Hi-Wax "NP105" manufactured by Mitsui Chemicals Co., Ltd.: the amount of comonomer was 0 Ear %) 10 parts by mass, a total of 100 parts by mass was obtained, and melt-kneading was carried out in a 30 mm twin-screw extruder to obtain Mw/Mn=11, Mz+1/Mn=146, MFR. = 7.0 g/10 min, [mmmm] = 96.5% of a mixture of propylene polymers (hereinafter referred to as "PP-3"). The stretched polypropylene film of the present invention was obtained in the same manner as in Example 1 except that the pellet was used as the polypropylene resin.

The thickness of the obtained film was 20 μm. The structure of the polypropylene constituting the film is shown in Table 1, and the film formation conditions are shown in Table 2. The physical properties of the obtained film are shown in Table 3.

(Example 4)

The stretched polypropylene film of the present invention was obtained in the same manner as in Example 3 except that the film was extended 5.5 times in the longitudinal direction and 12 times in the lateral direction.

The thickness of the obtained film was 20 μm. The structure of the polypropylene constituting the film is shown in Table 1, and the film formation conditions are shown in Table 2. The physical properties of the obtained film are shown in Table 3.

(Example 5)

The stretched polypropylene film produced in Example 1 was heat-treated at 170 ° C for 5 minutes in a tenter type hot air oven to obtain an extended polypropylene film of the present invention.

The thickness of the obtained film was 20 μm. The structure of the polypropylene constituting the film is shown in Table 1, and the film formation conditions are shown in Table 2. The physical properties of the obtained film are shown in Table 3.

(Example 6)

As the polypropylene resin, a propylene homopolymer having a Mw/Mn = 4.0, Mz+1/Mn = 23, MFR = 6.0 g/10 min, and [mmmm] = 98.7% (the amount of the comonomer was 0 mol%; Referred to as "PP-4"), in addition, The stretched polypropylene film of the present invention was obtained in the same manner as in Example 1.

The thickness of the obtained film was 20 μm. The structure of the polypropylene constituting the film is shown in Table 1, and the film formation conditions are shown in Table 2. The physical properties of the obtained film are shown in Table 3.

(Comparative Example 1)

As the polypropylene resin, a propylene-ethylene copolymer having Mw/Mn = 4, Mz+1/Mn = 21, MFR = 2.5 g/10 min, and [mmmm] = 97% (Sumitomo Noblen, manufactured by Sumitomo Chemical Co., Ltd.) was used. (registered trademark) FS2011DG3": comonomer amount is 0.6 mol%; hereinafter referred to as "PP-5"), the longitudinal extension temperature is set to 125 ° C, and the preheating temperature in the lateral extension is set to 168 ° C, lateral extension An extended polypropylene film was obtained in the same manner as in Example 1 except that the temperature was 155 ° C and the heat treatment temperature after the lateral stretching was 163 ° C.

The thickness of the obtained film was 20 μm. The structure of the polypropylene constituting the film is shown in Table 1, and the film formation conditions are shown in Table 2. The physical properties of the obtained film are shown in Table 3. Further, a graph obtained by differential scanning calorimetry (DSC) of the film is shown in Fig. 2 .

(Comparative Example 2)

The stretched polypropylene film was obtained in the same manner as in Comparative Example 1, except that the preheating temperature in the lateral stretching was 171 ° C, the lateral stretching temperature was 160 ° C, and the heat treatment temperature after the lateral stretching was 165 ° C.

The thickness of the obtained film was 20 μm. The structure of the polypropylene constituting the film is shown in Table 1, and the film formation conditions are shown in Table 2. The physical properties of the obtained film are shown in Table 3.

(Comparative Example 3)

As the polypropylene resin, a propylene homopolymer having a Mw/Mn = 4.3, Mz+1/Mn = 28, MFR = 0.5 g/10 min, and [mmmm] = 97% (the amount of the comonomer was 0 mol%; In the same manner as in Comparative Example 2, an extended polypropylene film was obtained, except for the abbreviated as "PP-6".

The thickness of the obtained film was 20 μm. The structure of the polypropylene constituting the film is shown in Table 1, and the film formation conditions are shown in Table 2. The physical properties of the obtained film are shown in Table 3.

(Comparative Example 4)

As the polypropylene resin, a polypropylene-based polymer (Novatec manufactured by Japan Polypropylene Co., Ltd.) having Mw/Mn = 2.8, Mz+1/Mn = 9.2, MFR = 30 g/10 min, and [mmmm] = 97.9% was used. In the same manner as in Example 1, the stretched polypropylene film was obtained in the same manner as in Example 1 except that the amount of the comonomer was 0 mol%; hereinafter referred to as "PP-7". Broken, unable to perform biaxial stretching.

[Industrial availability]

The polypropylene film of the present invention can be widely used for packaging applications, industrial applications, and the like, and in particular, it can be made thinner due to high rigidity, and can be reduced in cost and light in weight. Further, since the polypropylene film of the present invention has high heat resistance, it can be processed at a high temperature at the time of coating or printing, and production efficiency can be improved, and a coating agent or ink which has been previously difficult to use, and lamination can be used. Agents, etc. Further, the polypropylene film of the present invention is also suitably used as an insulating film for a capacitor or a motor, a back sheet of a solar cell, a barrier film of an inorganic oxide, and a base of a transparent conductive film such as ITO (indium tin oxide). membrane.

Claims (5)

An extended polypropylene film using a stretch film of a propylene-based polymer satisfying the following requirements (a) to (c), and satisfying the following requirements (d) and (e): (a) meso-penta-component The ratio is 96% or more; (b) the content of the comonomer other than propylene is 0.5 mol% or less; (c) the melt flow rate (MFR) is 0.5 g/10 min or more and 20 g/10 min or less; (d) relative to When the scattering intensity of the 110 surface of the α-type crystal of polypropylene measured by the wide-angle X-ray scattering method is plotted in the azimuth angle, the half value width of the maximum peak is 30 degrees or less; and (e) the density is 0.910 g/cm ³ or more. The extended polypropylene film according to claim 1, wherein the long period dimension obtained by long-period scattering peaks in the main alignment direction measured by the small angle X-ray scattering method is 40 nm or more. The stretched polypropylene film according to claim 1 or 2, wherein the stretched polypropylene film has a thickness of from 3 μm to 100 μm and is extended by at least uniaxial. The stretched polypropylene film according to claim 1 or 2, wherein the heat shrinkage ratio in the TD direction at 150 ° C and the heat shrinkage ratio in the MD direction at 150 ° C are both 10% or less. The stretched polypropylene film according to claim 1 or 2, wherein the haze is 6% or less.